Initial commit: Go 1.23 release state

src/cmd/compile/internal/inline/inlheur/actualexprpropbits_string.go

@@ -0,0 +1,58 @@
+// Code generated by "stringer -bitset -type ActualExprPropBits"; DO NOT EDIT.
+
+package inlheur
+
+import "strconv"
+import "bytes"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[ActualExprConstant-1]
+	_ = x[ActualExprIsConcreteConvIface-2]
+	_ = x[ActualExprIsFunc-4]
+	_ = x[ActualExprIsInlinableFunc-8]
+}
+
+var _ActualExprPropBits_value = [...]uint64{
+	0x1, /* ActualExprConstant */
+	0x2, /* ActualExprIsConcreteConvIface */
+	0x4, /* ActualExprIsFunc */
+	0x8, /* ActualExprIsInlinableFunc */
+}
+
+const _ActualExprPropBits_name = "ActualExprConstantActualExprIsConcreteConvIfaceActualExprIsFuncActualExprIsInlinableFunc"
+
+var _ActualExprPropBits_index = [...]uint8{0, 18, 47, 63, 88}
+
+func (i ActualExprPropBits) String() string {
+	var b bytes.Buffer
+
+	remain := uint64(i)
+	seen := false
+
+	for k, v := range _ActualExprPropBits_value {
+		x := _ActualExprPropBits_name[_ActualExprPropBits_index[k]:_ActualExprPropBits_index[k+1]]
+		if v == 0 {
+			if i == 0 {
+				b.WriteString(x)
+				return b.String()
+			}
+			continue
+		}
+		if (v & remain) == v {
+			remain &^= v
+			x := _ActualExprPropBits_name[_ActualExprPropBits_index[k]:_ActualExprPropBits_index[k+1]]
+			if seen {
+				b.WriteString("|")
+			}
+			seen = true
+			b.WriteString(x)
+		}
+	}
+	if remain == 0 {
+		return b.String()
+	}
+	return "ActualExprPropBits(0x" + strconv.FormatInt(int64(i), 16) + ")"
+}

src/cmd/compile/internal/inline/inlheur/analyze.go

@@ -0,0 +1,370 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/types"
+	"encoding/json"
+	"fmt"
+	"internal/buildcfg"
+	"io"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+)
+
+const (
+	debugTraceFuncs = 1 << iota
+	debugTraceFuncFlags
+	debugTraceResults
+	debugTraceParams
+	debugTraceExprClassify
+	debugTraceCalls
+	debugTraceScoring
+)
+
+// propAnalyzer interface is used for defining one or more analyzer
+// helper objects, each tasked with computing some specific subset of
+// the properties we're interested in. The assumption is that
+// properties are independent, so each new analyzer that implements
+// this interface can operate entirely on its own. For a given analyzer
+// there will be a sequence of calls to nodeVisitPre and nodeVisitPost
+// as the nodes within a function are visited, then a followup call to
+// setResults so that the analyzer can transfer its results into the
+// final properties object.
+type propAnalyzer interface {
+	nodeVisitPre(n ir.Node)
+	nodeVisitPost(n ir.Node)
+	setResults(funcProps *FuncProps)
+}
+
+// fnInlHeur contains inline heuristics state information about a
+// specific Go function being analyzed/considered by the inliner. Note
+// that in addition to constructing a fnInlHeur object by analyzing a
+// specific *ir.Func, there is also code in the test harness
+// (funcprops_test.go) that builds up fnInlHeur's by reading in and
+// parsing a dump. This is the reason why we have file/fname/line
+// fields below instead of just an *ir.Func field.
+type fnInlHeur struct {
+	props *FuncProps
+	cstab CallSiteTab
+	fname string
+	file  string
+	line  uint
+}
+
+var fpmap = map[*ir.Func]fnInlHeur{}
+
+// AnalyzeFunc computes function properties for fn and its contained
+// closures, updating the global 'fpmap' table. It is assumed that
+// "CanInline" has been run on fn and on the closures that feed
+// directly into calls; other closures not directly called will also
+// be checked inlinability for inlinability here in case they are
+// returned as a result.
+func AnalyzeFunc(fn *ir.Func, canInline func(*ir.Func), budgetForFunc func(*ir.Func) int32, inlineMaxBudget int) {
+	if fpmap == nil {
+		// If fpmap is nil this indicates that the main inliner pass is
+		// complete and we're doing inlining of wrappers (no heuristics
+		// used here).
+		return
+	}
+	if fn.OClosure != nil {
+		// closures will be processed along with their outer enclosing func.
+		return
+	}
+	enableDebugTraceIfEnv()
+	if debugTrace&debugTraceFuncs != 0 {
+		fmt.Fprintf(os.Stderr, "=-= AnalyzeFunc(%v)\n", fn)
+	}
+	// Build up a list containing 'fn' and any closures it contains. Along
+	// the way, test to see whether each closure is inlinable in case
+	// we might be returning it.
+	funcs := []*ir.Func{fn}
+	ir.VisitFuncAndClosures(fn, func(n ir.Node) {
+		if clo, ok := n.(*ir.ClosureExpr); ok {
+			funcs = append(funcs, clo.Func)
+		}
+	})
+
+	// Analyze the list of functions. We want to visit a given func
+	// only after the closures it contains have been processed, so
+	// iterate through the list in reverse order. Once a function has
+	// been analyzed, revisit the question of whether it should be
+	// inlinable; if it is over the default hairiness limit and it
+	// doesn't have any interesting properties, then we don't want
+	// the overhead of writing out its inline body.
+	nameFinder := newNameFinder(fn)
+	for i := len(funcs) - 1; i >= 0; i-- {
+		f := funcs[i]
+		if f.OClosure != nil && !f.InlinabilityChecked() {
+			canInline(f)
+		}
+		funcProps := analyzeFunc(f, inlineMaxBudget, nameFinder)
+		revisitInlinability(f, funcProps, budgetForFunc)
+		if f.Inl != nil {
+			f.Inl.Properties = funcProps.SerializeToString()
+		}
+	}
+	disableDebugTrace()
+}
+
+// TearDown is invoked at the end of the main inlining pass; doing
+// function analysis and call site scoring is unlikely to help a lot
+// after this point, so nil out fpmap and other globals to reclaim
+// storage.
+func TearDown() {
+	fpmap = nil
+	scoreCallsCache.tab = nil
+	scoreCallsCache.csl = nil
+}
+
+func analyzeFunc(fn *ir.Func, inlineMaxBudget int, nf *nameFinder) *FuncProps {
+	if funcInlHeur, ok := fpmap[fn]; ok {
+		return funcInlHeur.props
+	}
+	funcProps, fcstab := computeFuncProps(fn, inlineMaxBudget, nf)
+	file, line := fnFileLine(fn)
+	entry := fnInlHeur{
+		fname: fn.Sym().Name,
+		file:  file,
+		line:  line,
+		props: funcProps,
+		cstab: fcstab,
+	}
+	fn.SetNeverReturns(entry.props.Flags&FuncPropNeverReturns != 0)
+	fpmap[fn] = entry
+	if fn.Inl != nil && fn.Inl.Properties == "" {
+		fn.Inl.Properties = entry.props.SerializeToString()
+	}
+	return funcProps
+}
+
+// revisitInlinability revisits the question of whether to continue to
+// treat function 'fn' as an inline candidate based on the set of
+// properties we've computed for it. If (for example) it has an
+// initial size score of 150 and no interesting properties to speak
+// of, then there isn't really any point to moving ahead with it as an
+// inline candidate.
+func revisitInlinability(fn *ir.Func, funcProps *FuncProps, budgetForFunc func(*ir.Func) int32) {
+	if fn.Inl == nil {
+		return
+	}
+	maxAdj := int32(LargestNegativeScoreAdjustment(fn, funcProps))
+	budget := budgetForFunc(fn)
+	if fn.Inl.Cost+maxAdj > budget {
+		fn.Inl = nil
+	}
+}
+
+// computeFuncProps examines the Go function 'fn' and computes for it
+// a function "properties" object, to be used to drive inlining
+// heuristics. See comments on the FuncProps type for more info.
+func computeFuncProps(fn *ir.Func, inlineMaxBudget int, nf *nameFinder) (*FuncProps, CallSiteTab) {
+	if debugTrace&debugTraceFuncs != 0 {
+		fmt.Fprintf(os.Stderr, "=-= starting analysis of func %v:\n%+v\n",
+			fn, fn)
+	}
+	funcProps := new(FuncProps)
+	ffa := makeFuncFlagsAnalyzer(fn)
+	analyzers := []propAnalyzer{ffa}
+	analyzers = addResultsAnalyzer(fn, analyzers, funcProps, inlineMaxBudget, nf)
+	analyzers = addParamsAnalyzer(fn, analyzers, funcProps, nf)
+	runAnalyzersOnFunction(fn, analyzers)
+	for _, a := range analyzers {
+		a.setResults(funcProps)
+	}
+	cstab := computeCallSiteTable(fn, fn.Body, nil, ffa.panicPathTable(), 0, nf)
+	return funcProps, cstab
+}
+
+func runAnalyzersOnFunction(fn *ir.Func, analyzers []propAnalyzer) {
+	var doNode func(ir.Node) bool
+	doNode = func(n ir.Node) bool {
+		for _, a := range analyzers {
+			a.nodeVisitPre(n)
+		}
+		ir.DoChildren(n, doNode)
+		for _, a := range analyzers {
+			a.nodeVisitPost(n)
+		}
+		return false
+	}
+	doNode(fn)
+}
+
+func propsForFunc(fn *ir.Func) *FuncProps {
+	if funcInlHeur, ok := fpmap[fn]; ok {
+		return funcInlHeur.props
+	} else if fn.Inl != nil && fn.Inl.Properties != "" {
+		// FIXME: considering adding some sort of cache or table
+		// for deserialized properties of imported functions.
+		return DeserializeFromString(fn.Inl.Properties)
+	}
+	return nil
+}
+
+func fnFileLine(fn *ir.Func) (string, uint) {
+	p := base.Ctxt.InnermostPos(fn.Pos())
+	return filepath.Base(p.Filename()), p.Line()
+}
+
+func Enabled() bool {
+	return buildcfg.Experiment.NewInliner || UnitTesting()
+}
+
+func UnitTesting() bool {
+	return base.Debug.DumpInlFuncProps != "" ||
+		base.Debug.DumpInlCallSiteScores != 0
+}
+
+// DumpFuncProps computes and caches function properties for the func
+// 'fn', writing out a description of the previously computed set of
+// properties to the file given in 'dumpfile'. Used for the
+// "-d=dumpinlfuncprops=..." command line flag, intended for use
+// primarily in unit testing.
+func DumpFuncProps(fn *ir.Func, dumpfile string) {
+	if fn != nil {
+		if fn.OClosure != nil {
+			// closures will be processed along with their outer enclosing func.
+			return
+		}
+		captureFuncDumpEntry(fn)
+		ir.VisitFuncAndClosures(fn, func(n ir.Node) {
+			if clo, ok := n.(*ir.ClosureExpr); ok {
+				captureFuncDumpEntry(clo.Func)
+			}
+		})
+	} else {
+		emitDumpToFile(dumpfile)
+	}
+}
+
+// emitDumpToFile writes out the buffer function property dump entries
+// to a file, for unit testing. Dump entries need to be sorted by
+// definition line, and due to generics we need to account for the
+// possibility that several ir.Func's will have the same def line.
+func emitDumpToFile(dumpfile string) {
+	mode := os.O_WRONLY | os.O_CREATE | os.O_TRUNC
+	if dumpfile[0] == '+' {
+		dumpfile = dumpfile[1:]
+		mode = os.O_WRONLY | os.O_APPEND | os.O_CREATE
+	}
+	if dumpfile[0] == '%' {
+		dumpfile = dumpfile[1:]
+		d, b := filepath.Dir(dumpfile), filepath.Base(dumpfile)
+		ptag := strings.ReplaceAll(types.LocalPkg.Path, "/", ":")
+		dumpfile = d + "/" + ptag + "." + b
+	}
+	outf, err := os.OpenFile(dumpfile, mode, 0644)
+	if err != nil {
+		base.Fatalf("opening function props dump file %q: %v\n", dumpfile, err)
+	}
+	defer outf.Close()
+	dumpFilePreamble(outf)
+
+	atline := map[uint]uint{}
+	sl := make([]fnInlHeur, 0, len(dumpBuffer))
+	for _, e := range dumpBuffer {
+		sl = append(sl, e)
+		atline[e.line] = atline[e.line] + 1
+	}
+	sl = sortFnInlHeurSlice(sl)
+
+	prevline := uint(0)
+	for _, entry := range sl {
+		idx := uint(0)
+		if prevline == entry.line {
+			idx++
+		}
+		prevline = entry.line
+		atl := atline[entry.line]
+		if err := dumpFnPreamble(outf, &entry, nil, idx, atl); err != nil {
+			base.Fatalf("function props dump: %v\n", err)
+		}
+	}
+	dumpBuffer = nil
+}
+
+// captureFuncDumpEntry grabs the function properties object for 'fn'
+// and enqueues it for later dumping. Used for the
+// "-d=dumpinlfuncprops=..." command line flag, intended for use
+// primarily in unit testing.
+func captureFuncDumpEntry(fn *ir.Func) {
+	// avoid capturing compiler-generated equality funcs.
+	if strings.HasPrefix(fn.Sym().Name, ".eq.") {
+		return
+	}
+	funcInlHeur, ok := fpmap[fn]
+	if !ok {
+		// Missing entry is expected for functions that are too large
+		// to inline. We still want to write out call site scores in
+		// this case however.
+		funcInlHeur = fnInlHeur{cstab: callSiteTab}
+	}
+	if dumpBuffer == nil {
+		dumpBuffer = make(map[*ir.Func]fnInlHeur)
+	}
+	if _, ok := dumpBuffer[fn]; ok {
+		return
+	}
+	if debugTrace&debugTraceFuncs != 0 {
+		fmt.Fprintf(os.Stderr, "=-= capturing dump for %v:\n", fn)
+	}
+	dumpBuffer[fn] = funcInlHeur
+}
+
+// dumpFilePreamble writes out a file-level preamble for a given
+// Go function as part of a function properties dump.
+func dumpFilePreamble(w io.Writer) {
+	fmt.Fprintf(w, "// DO NOT EDIT (use 'go test -v -update-expected' instead.)\n")
+	fmt.Fprintf(w, "// See cmd/compile/internal/inline/inlheur/testdata/props/README.txt\n")
+	fmt.Fprintf(w, "// for more information on the format of this file.\n")
+	fmt.Fprintf(w, "// %s\n", preambleDelimiter)
+}
+
+// dumpFnPreamble writes out a function-level preamble for a given
+// Go function as part of a function properties dump. See the
+// README.txt file in testdata/props for more on the format of
+// this preamble.
+func dumpFnPreamble(w io.Writer, funcInlHeur *fnInlHeur, ecst encodedCallSiteTab, idx, atl uint) error {
+	fmt.Fprintf(w, "// %s %s %d %d %d\n",
+		funcInlHeur.file, funcInlHeur.fname, funcInlHeur.line, idx, atl)
+	// emit props as comments, followed by delimiter
+	fmt.Fprintf(w, "%s// %s\n", funcInlHeur.props.ToString("// "), comDelimiter)
+	data, err := json.Marshal(funcInlHeur.props)
+	if err != nil {
+		return fmt.Errorf("marshal error %v\n", err)
+	}
+	fmt.Fprintf(w, "// %s\n", string(data))
+	dumpCallSiteComments(w, funcInlHeur.cstab, ecst)
+	fmt.Fprintf(w, "// %s\n", fnDelimiter)
+	return nil
+}
+
+// sortFnInlHeurSlice sorts a slice of fnInlHeur based on
+// the starting line of the function definition, then by name.
+func sortFnInlHeurSlice(sl []fnInlHeur) []fnInlHeur {
+	sort.SliceStable(sl, func(i, j int) bool {
+		if sl[i].line != sl[j].line {
+			return sl[i].line < sl[j].line
+		}
+		return sl[i].fname < sl[j].fname
+	})
+	return sl
+}
+
+// delimiters written to various preambles to make parsing of
+// dumps easier.
+const preambleDelimiter = "<endfilepreamble>"
+const fnDelimiter = "<endfuncpreamble>"
+const comDelimiter = "<endpropsdump>"
+const csDelimiter = "<endcallsites>"
+
+// dumpBuffer stores up function properties dumps when
+// "-d=dumpinlfuncprops=..." is in effect.
+var dumpBuffer map[*ir.Func]fnInlHeur

src/cmd/compile/internal/inline/inlheur/analyze_func_callsites.go

@@ -0,0 +1,413 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/pgoir"
+	"cmd/compile/internal/typecheck"
+	"fmt"
+	"os"
+	"strings"
+)
+
+type callSiteAnalyzer struct {
+	fn *ir.Func
+	*nameFinder
+}
+
+type callSiteTableBuilder struct {
+	fn *ir.Func
+	*nameFinder
+	cstab    CallSiteTab
+	ptab     map[ir.Node]pstate
+	nstack   []ir.Node
+	loopNest int
+	isInit   bool
+}
+
+func makeCallSiteAnalyzer(fn *ir.Func) *callSiteAnalyzer {
+	return &callSiteAnalyzer{
+		fn:         fn,
+		nameFinder: newNameFinder(fn),
+	}
+}
+
+func makeCallSiteTableBuilder(fn *ir.Func, cstab CallSiteTab, ptab map[ir.Node]pstate, loopNestingLevel int, nf *nameFinder) *callSiteTableBuilder {
+	isInit := fn.IsPackageInit() || strings.HasPrefix(fn.Sym().Name, "init.")
+	return &callSiteTableBuilder{
+		fn:         fn,
+		cstab:      cstab,
+		ptab:       ptab,
+		isInit:     isInit,
+		loopNest:   loopNestingLevel,
+		nstack:     []ir.Node{fn},
+		nameFinder: nf,
+	}
+}
+
+// computeCallSiteTable builds and returns a table of call sites for
+// the specified region in function fn. A region here corresponds to a
+// specific subtree within the AST for a function. The main intended
+// use cases are for 'region' to be either A) an entire function body,
+// or B) an inlined call expression.
+func computeCallSiteTable(fn *ir.Func, region ir.Nodes, cstab CallSiteTab, ptab map[ir.Node]pstate, loopNestingLevel int, nf *nameFinder) CallSiteTab {
+	cstb := makeCallSiteTableBuilder(fn, cstab, ptab, loopNestingLevel, nf)
+	var doNode func(ir.Node) bool
+	doNode = func(n ir.Node) bool {
+		cstb.nodeVisitPre(n)
+		ir.DoChildren(n, doNode)
+		cstb.nodeVisitPost(n)
+		return false
+	}
+	for _, n := range region {
+		doNode(n)
+	}
+	return cstb.cstab
+}
+
+func (cstb *callSiteTableBuilder) flagsForNode(call *ir.CallExpr) CSPropBits {
+	var r CSPropBits
+
+	if debugTrace&debugTraceCalls != 0 {
+		fmt.Fprintf(os.Stderr, "=-= analyzing call at %s\n",
+			fmtFullPos(call.Pos()))
+	}
+
+	// Set a bit if this call is within a loop.
+	if cstb.loopNest > 0 {
+		r |= CallSiteInLoop
+	}
+
+	// Set a bit if the call is within an init function (either
+	// compiler-generated or user-written).
+	if cstb.isInit {
+		r |= CallSiteInInitFunc
+	}
+
+	// Decide whether to apply the panic path heuristic. Hack: don't
+	// apply this heuristic in the function "main.main" (mostly just
+	// to avoid annoying users).
+	if !isMainMain(cstb.fn) {
+		r = cstb.determinePanicPathBits(call, r)
+	}
+
+	return r
+}
+
+// determinePanicPathBits updates the CallSiteOnPanicPath bit within
+// "r" if we think this call is on an unconditional path to
+// panic/exit. Do this by walking back up the node stack to see if we
+// can find either A) an enclosing panic, or B) a statement node that
+// we've determined leads to a panic/exit.
+func (cstb *callSiteTableBuilder) determinePanicPathBits(call ir.Node, r CSPropBits) CSPropBits {
+	cstb.nstack = append(cstb.nstack, call)
+	defer func() {
+		cstb.nstack = cstb.nstack[:len(cstb.nstack)-1]
+	}()
+
+	for ri := range cstb.nstack[:len(cstb.nstack)-1] {
+		i := len(cstb.nstack) - ri - 1
+		n := cstb.nstack[i]
+		_, isCallExpr := n.(*ir.CallExpr)
+		_, isStmt := n.(ir.Stmt)
+		if isCallExpr {
+			isStmt = false
+		}
+
+		if debugTrace&debugTraceCalls != 0 {
+			ps, inps := cstb.ptab[n]
+			fmt.Fprintf(os.Stderr, "=-= callpar %d op=%s ps=%s inptab=%v stmt=%v\n", i, n.Op().String(), ps.String(), inps, isStmt)
+		}
+
+		if n.Op() == ir.OPANIC {
+			r |= CallSiteOnPanicPath
+			break
+		}
+		if v, ok := cstb.ptab[n]; ok {
+			if v == psCallsPanic {
+				r |= CallSiteOnPanicPath
+				break
+			}
+			if isStmt {
+				break
+			}
+		}
+	}
+	return r
+}
+
+// propsForArg returns property bits for a given call argument expression arg.
+func (cstb *callSiteTableBuilder) propsForArg(arg ir.Node) ActualExprPropBits {
+	if cval := cstb.constValue(arg); cval != nil {
+		return ActualExprConstant
+	}
+	if cstb.isConcreteConvIface(arg) {
+		return ActualExprIsConcreteConvIface
+	}
+	fname := cstb.funcName(arg)
+	if fname != nil {
+		if fn := fname.Func; fn != nil && typecheck.HaveInlineBody(fn) {
+			return ActualExprIsInlinableFunc
+		}
+		return ActualExprIsFunc
+	}
+	return 0
+}
+
+// argPropsForCall returns a slice of argument properties for the
+// expressions being passed to the callee in the specific call
+// expression; these will be stored in the CallSite object for a given
+// call and then consulted when scoring. If no arg has any interesting
+// properties we try to save some space and return a nil slice.
+func (cstb *callSiteTableBuilder) argPropsForCall(ce *ir.CallExpr) []ActualExprPropBits {
+	rv := make([]ActualExprPropBits, len(ce.Args))
+	somethingInteresting := false
+	for idx := range ce.Args {
+		argProp := cstb.propsForArg(ce.Args[idx])
+		somethingInteresting = somethingInteresting || (argProp != 0)
+		rv[idx] = argProp
+	}
+	if !somethingInteresting {
+		return nil
+	}
+	return rv
+}
+
+func (cstb *callSiteTableBuilder) addCallSite(callee *ir.Func, call *ir.CallExpr) {
+	flags := cstb.flagsForNode(call)
+	argProps := cstb.argPropsForCall(call)
+	if debugTrace&debugTraceCalls != 0 {
+		fmt.Fprintf(os.Stderr, "=-= props %+v for call %v\n", argProps, call)
+	}
+	// FIXME: maybe bulk-allocate these?
+	cs := &CallSite{
+		Call:     call,
+		Callee:   callee,
+		Assign:   cstb.containingAssignment(call),
+		ArgProps: argProps,
+		Flags:    flags,
+		ID:       uint(len(cstb.cstab)),
+	}
+	if _, ok := cstb.cstab[call]; ok {
+		fmt.Fprintf(os.Stderr, "*** cstab duplicate entry at: %s\n",
+			fmtFullPos(call.Pos()))
+		fmt.Fprintf(os.Stderr, "*** call: %+v\n", call)
+		panic("bad")
+	}
+	// Set initial score for callsite to the cost computed
+	// by CanInline; this score will be refined later based
+	// on heuristics.
+	cs.Score = int(callee.Inl.Cost)
+
+	if cstb.cstab == nil {
+		cstb.cstab = make(CallSiteTab)
+	}
+	cstb.cstab[call] = cs
+	if debugTrace&debugTraceCalls != 0 {
+		fmt.Fprintf(os.Stderr, "=-= added callsite: caller=%v callee=%v n=%s\n",
+			cstb.fn, callee, fmtFullPos(call.Pos()))
+	}
+}
+
+func (cstb *callSiteTableBuilder) nodeVisitPre(n ir.Node) {
+	switch n.Op() {
+	case ir.ORANGE, ir.OFOR:
+		if !hasTopLevelLoopBodyReturnOrBreak(loopBody(n)) {
+			cstb.loopNest++
+		}
+	case ir.OCALLFUNC:
+		ce := n.(*ir.CallExpr)
+		callee := pgoir.DirectCallee(ce.Fun)
+		if callee != nil && callee.Inl != nil {
+			cstb.addCallSite(callee, ce)
+		}
+	}
+	cstb.nstack = append(cstb.nstack, n)
+}
+
+func (cstb *callSiteTableBuilder) nodeVisitPost(n ir.Node) {
+	cstb.nstack = cstb.nstack[:len(cstb.nstack)-1]
+	switch n.Op() {
+	case ir.ORANGE, ir.OFOR:
+		if !hasTopLevelLoopBodyReturnOrBreak(loopBody(n)) {
+			cstb.loopNest--
+		}
+	}
+}
+
+func loopBody(n ir.Node) ir.Nodes {
+	if forst, ok := n.(*ir.ForStmt); ok {
+		return forst.Body
+	}
+	if rst, ok := n.(*ir.RangeStmt); ok {
+		return rst.Body
+	}
+	return nil
+}
+
+// hasTopLevelLoopBodyReturnOrBreak examines the body of a "for" or
+// "range" loop to try to verify that it is a real loop, as opposed to
+// a construct that is syntactically loopy but doesn't actually iterate
+// multiple times, like:
+//
+//	for {
+//	  blah()
+//	  return 1
+//	}
+//
+// [Remark: the pattern above crops up quite a bit in the source code
+// for the compiler itself, e.g. the auto-generated rewrite code]
+//
+// Note that we don't look for GOTO statements here, so it's possible
+// we'll get the wrong result for a loop with complicated control
+// jumps via gotos.
+func hasTopLevelLoopBodyReturnOrBreak(loopBody ir.Nodes) bool {
+	for _, n := range loopBody {
+		if n.Op() == ir.ORETURN || n.Op() == ir.OBREAK {
+			return true
+		}
+	}
+	return false
+}
+
+// containingAssignment returns the top-level assignment statement
+// for a statement level function call "n". Examples:
+//
+//	x := foo()
+//	x, y := bar(z, baz())
+//	if blah() { ...
+//
+// Here the top-level assignment statement for the foo() call is the
+// statement assigning to "x"; the top-level assignment for "bar()"
+// call is the assignment to x,y. For the baz() and blah() calls,
+// there is no top level assignment statement.
+//
+// The unstated goal here is that we want to use the containing
+// assignment to establish a connection between a given call and the
+// variables to which its results/returns are being assigned.
+//
+// Note that for the "bar" command above, the front end sometimes
+// decomposes this into two assignments, the first one assigning the
+// call to a pair of auto-temps, then the second one assigning the
+// auto-temps to the user-visible vars. This helper will return the
+// second (outer) of these two.
+func (cstb *callSiteTableBuilder) containingAssignment(n ir.Node) ir.Node {
+	parent := cstb.nstack[len(cstb.nstack)-1]
+
+	// assignsOnlyAutoTemps returns TRUE of the specified OAS2FUNC
+	// node assigns only auto-temps.
+	assignsOnlyAutoTemps := func(x ir.Node) bool {
+		alst := x.(*ir.AssignListStmt)
+		oa2init := alst.Init()
+		if len(oa2init) == 0 {
+			return false
+		}
+		for _, v := range oa2init {
+			d := v.(*ir.Decl)
+			if !ir.IsAutoTmp(d.X) {
+				return false
+			}
+		}
+		return true
+	}
+
+	// Simple case: x := foo()
+	if parent.Op() == ir.OAS {
+		return parent
+	}
+
+	// Multi-return case: x, y := bar()
+	if parent.Op() == ir.OAS2FUNC {
+		// Hack city: if the result vars are auto-temps, try looking
+		// for an outer assignment in the tree. The code shape we're
+		// looking for here is:
+		//
+		// OAS1({x,y},OCONVNOP(OAS2FUNC({auto1,auto2},OCALLFUNC(bar))))
+		//
+		if assignsOnlyAutoTemps(parent) {
+			par2 := cstb.nstack[len(cstb.nstack)-2]
+			if par2.Op() == ir.OAS2 {
+				return par2
+			}
+			if par2.Op() == ir.OCONVNOP {
+				par3 := cstb.nstack[len(cstb.nstack)-3]
+				if par3.Op() == ir.OAS2 {
+					return par3
+				}
+			}
+		}
+	}
+
+	return nil
+}
+
+// UpdateCallsiteTable handles updating of callerfn's call site table
+// after an inlined has been carried out, e.g. the call at 'n' as been
+// turned into the inlined call expression 'ic' within function
+// callerfn. The chief thing of interest here is to make sure that any
+// call nodes within 'ic' are added to the call site table for
+// 'callerfn' and scored appropriately.
+func UpdateCallsiteTable(callerfn *ir.Func, n *ir.CallExpr, ic *ir.InlinedCallExpr) {
+	enableDebugTraceIfEnv()
+	defer disableDebugTrace()
+
+	funcInlHeur, ok := fpmap[callerfn]
+	if !ok {
+		// This can happen for compiler-generated wrappers.
+		if debugTrace&debugTraceCalls != 0 {
+			fmt.Fprintf(os.Stderr, "=-= early exit, no entry for caller fn %v\n", callerfn)
+		}
+		return
+	}
+
+	if debugTrace&debugTraceCalls != 0 {
+		fmt.Fprintf(os.Stderr, "=-= UpdateCallsiteTable(caller=%v, cs=%s)\n",
+			callerfn, fmtFullPos(n.Pos()))
+	}
+
+	// Mark the call in question as inlined.
+	oldcs, ok := funcInlHeur.cstab[n]
+	if !ok {
+		// This can happen for compiler-generated wrappers.
+		return
+	}
+	oldcs.aux |= csAuxInlined
+
+	if debugTrace&debugTraceCalls != 0 {
+		fmt.Fprintf(os.Stderr, "=-= marked as inlined: callee=%v %s\n",
+			oldcs.Callee, EncodeCallSiteKey(oldcs))
+	}
+
+	// Walk the inlined call region to collect new callsites.
+	var icp pstate
+	if oldcs.Flags&CallSiteOnPanicPath != 0 {
+		icp = psCallsPanic
+	}
+	var loopNestLevel int
+	if oldcs.Flags&CallSiteInLoop != 0 {
+		loopNestLevel = 1
+	}
+	ptab := map[ir.Node]pstate{ic: icp}
+	nf := newNameFinder(nil)
+	icstab := computeCallSiteTable(callerfn, ic.Body, nil, ptab, loopNestLevel, nf)
+
+	// Record parent callsite. This is primarily for debug output.
+	for _, cs := range icstab {
+		cs.parent = oldcs
+	}
+
+	// Score the calls in the inlined body. Note the setting of
+	// "doCallResults" to false here: at the moment there isn't any
+	// easy way to localize or region-ize the work done by
+	// "rescoreBasedOnCallResultUses", which currently does a walk
+	// over the entire function to look for uses of a given set of
+	// results. Similarly we're passing nil to makeCallSiteAnalyzer,
+	// so as to run name finding without the use of static value &
+	// friends.
+	csa := makeCallSiteAnalyzer(nil)
+	const doCallResults = false
+	csa.scoreCallsRegion(callerfn, ic.Body, icstab, doCallResults, ic)
+}

src/cmd/compile/internal/inline/inlheur/analyze_func_flags.go

@@ -0,0 +1,356 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/types"
+	"fmt"
+	"os"
+)
+
+// funcFlagsAnalyzer computes the "Flags" value for the FuncProps
+// object we're computing. The main item of interest here is "nstate",
+// which stores the disposition of a given ir Node with respect to the
+// flags/properties we're trying to compute.
+type funcFlagsAnalyzer struct {
+	fn     *ir.Func
+	nstate map[ir.Node]pstate
+	noInfo bool // set if we see something inscrutable/un-analyzable
+}
+
+// pstate keeps track of the disposition of a given node and its
+// children with respect to panic/exit calls.
+type pstate int
+
+const (
+	psNoInfo     pstate = iota // nothing interesting about this node
+	psCallsPanic               // node causes call to panic or os.Exit
+	psMayReturn                // executing node may trigger a "return" stmt
+	psTop                      // dataflow lattice "top" element
+)
+
+func makeFuncFlagsAnalyzer(fn *ir.Func) *funcFlagsAnalyzer {
+	return &funcFlagsAnalyzer{
+		fn:     fn,
+		nstate: make(map[ir.Node]pstate),
+	}
+}
+
+// setResults transfers func flag results to 'funcProps'.
+func (ffa *funcFlagsAnalyzer) setResults(funcProps *FuncProps) {
+	var rv FuncPropBits
+	if !ffa.noInfo && ffa.stateForList(ffa.fn.Body) == psCallsPanic {
+		rv = FuncPropNeverReturns
+	}
+	// This is slightly hacky and not at all required, but include a
+	// special case for main.main, which often ends in a call to
+	// os.Exit. People who write code like this (very common I
+	// imagine)
+	//
+	//   func main() {
+	//     rc = perform()
+	//     ...
+	//     foo()
+	//     os.Exit(rc)
+	//   }
+	//
+	// will be constantly surprised when foo() is inlined in many
+	// other spots in the program but not in main().
+	if isMainMain(ffa.fn) {
+		rv &^= FuncPropNeverReturns
+	}
+	funcProps.Flags = rv
+}
+
+func (ffa *funcFlagsAnalyzer) getState(n ir.Node) pstate {
+	return ffa.nstate[n]
+}
+
+func (ffa *funcFlagsAnalyzer) setState(n ir.Node, st pstate) {
+	if st != psNoInfo {
+		ffa.nstate[n] = st
+	}
+}
+
+func (ffa *funcFlagsAnalyzer) updateState(n ir.Node, st pstate) {
+	if st == psNoInfo {
+		delete(ffa.nstate, n)
+	} else {
+		ffa.nstate[n] = st
+	}
+}
+
+func (ffa *funcFlagsAnalyzer) panicPathTable() map[ir.Node]pstate {
+	return ffa.nstate
+}
+
+// blockCombine merges together states as part of a linear sequence of
+// statements, where 'pred' and 'succ' are analysis results for a pair
+// of consecutive statements. Examples:
+//
+//	case 1:             case 2:
+//	    panic("foo")      if q { return x }        <-pred
+//	    return x          panic("boo")             <-succ
+//
+// In case 1, since the pred state is "always panic" it doesn't matter
+// what the succ state is, hence the state for the combination of the
+// two blocks is "always panics". In case 2, because there is a path
+// to return that avoids the panic in succ, the state for the
+// combination of the two statements is "may return".
+func blockCombine(pred, succ pstate) pstate {
+	switch succ {
+	case psTop:
+		return pred
+	case psMayReturn:
+		if pred == psCallsPanic {
+			return psCallsPanic
+		}
+		return psMayReturn
+	case psNoInfo:
+		return pred
+	case psCallsPanic:
+		if pred == psMayReturn {
+			return psMayReturn
+		}
+		return psCallsPanic
+	}
+	panic("should never execute")
+}
+
+// branchCombine combines two states at a control flow branch point where
+// either p1 or p2 executes (as in an "if" statement).
+func branchCombine(p1, p2 pstate) pstate {
+	if p1 == psCallsPanic && p2 == psCallsPanic {
+		return psCallsPanic
+	}
+	if p1 == psMayReturn || p2 == psMayReturn {
+		return psMayReturn
+	}
+	return psNoInfo
+}
+
+// stateForList walks through a list of statements and computes the
+// state/disposition for the entire list as a whole, as well
+// as updating disposition of intermediate nodes.
+func (ffa *funcFlagsAnalyzer) stateForList(list ir.Nodes) pstate {
+	st := psTop
+	// Walk the list backwards so that we can update the state for
+	// earlier list elements based on what we find out about their
+	// successors. Example:
+	//
+	//        if ... {
+	//  L10:    foo()
+	//  L11:    <stmt>
+	//  L12:    panic(...)
+	//        }
+	//
+	// After combining the dispositions for line 11 and 12, we want to
+	// update the state for the call at line 10 based on that combined
+	// disposition (if L11 has no path to "return", then the call at
+	// line 10 will be on a panic path).
+	for i := len(list) - 1; i >= 0; i-- {
+		n := list[i]
+		psi := ffa.getState(n)
+		if debugTrace&debugTraceFuncFlags != 0 {
+			fmt.Fprintf(os.Stderr, "=-= %v: stateForList n=%s ps=%s\n",
+				ir.Line(n), n.Op().String(), psi.String())
+		}
+		st = blockCombine(psi, st)
+		ffa.updateState(n, st)
+	}
+	if st == psTop {
+		st = psNoInfo
+	}
+	return st
+}
+
+func isMainMain(fn *ir.Func) bool {
+	s := fn.Sym()
+	return (s.Pkg.Name == "main" && s.Name == "main")
+}
+
+func isWellKnownFunc(s *types.Sym, pkg, name string) bool {
+	return s.Pkg.Path == pkg && s.Name == name
+}
+
+// isExitCall reports TRUE if the node itself is an unconditional
+// call to os.Exit(), a panic, or a function that does likewise.
+func isExitCall(n ir.Node) bool {
+	if n.Op() != ir.OCALLFUNC {
+		return false
+	}
+	cx := n.(*ir.CallExpr)
+	name := ir.StaticCalleeName(cx.Fun)
+	if name == nil {
+		return false
+	}
+	s := name.Sym()
+	if isWellKnownFunc(s, "os", "Exit") ||
+		isWellKnownFunc(s, "runtime", "throw") {
+		return true
+	}
+	if funcProps := propsForFunc(name.Func); funcProps != nil {
+		if funcProps.Flags&FuncPropNeverReturns != 0 {
+			return true
+		}
+	}
+	return name.Func.NeverReturns()
+}
+
+// pessimize is called to record the fact that we saw something in the
+// function that renders it entirely impossible to analyze.
+func (ffa *funcFlagsAnalyzer) pessimize() {
+	ffa.noInfo = true
+}
+
+// shouldVisit reports TRUE if this is an interesting node from the
+// perspective of computing function flags. NB: due to the fact that
+// ir.CallExpr implements the Stmt interface, we wind up visiting
+// a lot of nodes that we don't really need to, but these can
+// simply be screened out as part of the visit.
+func shouldVisit(n ir.Node) bool {
+	_, isStmt := n.(ir.Stmt)
+	return n.Op() != ir.ODCL &&
+		(isStmt || n.Op() == ir.OCALLFUNC || n.Op() == ir.OPANIC)
+}
+
+// nodeVisitPost helps implement the propAnalyzer interface; when
+// called on a given node, it decides the disposition of that node
+// based on the state(s) of the node's children.
+func (ffa *funcFlagsAnalyzer) nodeVisitPost(n ir.Node) {
+	if debugTrace&debugTraceFuncFlags != 0 {
+		fmt.Fprintf(os.Stderr, "=+= nodevis %v %s should=%v\n",
+			ir.Line(n), n.Op().String(), shouldVisit(n))
+	}
+	if !shouldVisit(n) {
+		return
+	}
+	var st pstate
+	switch n.Op() {
+	case ir.OCALLFUNC:
+		if isExitCall(n) {
+			st = psCallsPanic
+		}
+	case ir.OPANIC:
+		st = psCallsPanic
+	case ir.ORETURN:
+		st = psMayReturn
+	case ir.OBREAK, ir.OCONTINUE:
+		// FIXME: this handling of break/continue is sub-optimal; we
+		// have them as "mayReturn" in order to help with this case:
+		//
+		//   for {
+		//     if q() { break }
+		//     panic(...)
+		//   }
+		//
+		// where the effect of the 'break' is to cause the subsequent
+		// panic to be skipped. One possible improvement would be to
+		// track whether the currently enclosing loop is a "for {" or
+		// a for/range with condition, then use mayReturn only for the
+		// former. Note also that "break X" or "continue X" is treated
+		// the same as "goto", since we don't have a good way to track
+		// the target of the branch.
+		st = psMayReturn
+		n := n.(*ir.BranchStmt)
+		if n.Label != nil {
+			ffa.pessimize()
+		}
+	case ir.OBLOCK:
+		n := n.(*ir.BlockStmt)
+		st = ffa.stateForList(n.List)
+	case ir.OCASE:
+		if ccst, ok := n.(*ir.CaseClause); ok {
+			st = ffa.stateForList(ccst.Body)
+		} else if ccst, ok := n.(*ir.CommClause); ok {
+			st = ffa.stateForList(ccst.Body)
+		} else {
+			panic("unexpected")
+		}
+	case ir.OIF:
+		n := n.(*ir.IfStmt)
+		st = branchCombine(ffa.stateForList(n.Body), ffa.stateForList(n.Else))
+	case ir.OFOR:
+		// Treat for { XXX } like a block.
+		// Treat for <cond> { XXX } like an if statement with no else.
+		n := n.(*ir.ForStmt)
+		bst := ffa.stateForList(n.Body)
+		if n.Cond == nil {
+			st = bst
+		} else {
+			if bst == psMayReturn {
+				st = psMayReturn
+			}
+		}
+	case ir.ORANGE:
+		// Treat for range { XXX } like an if statement with no else.
+		n := n.(*ir.RangeStmt)
+		if ffa.stateForList(n.Body) == psMayReturn {
+			st = psMayReturn
+		}
+	case ir.OGOTO:
+		// punt if we see even one goto. if we built a control
+		// flow graph we could do more, but this is just a tree walk.
+		ffa.pessimize()
+	case ir.OSELECT:
+		// process selects for "may return" but not "always panics",
+		// the latter case seems very improbable.
+		n := n.(*ir.SelectStmt)
+		if len(n.Cases) != 0 {
+			st = psTop
+			for _, c := range n.Cases {
+				st = branchCombine(ffa.stateForList(c.Body), st)
+			}
+		}
+	case ir.OSWITCH:
+		n := n.(*ir.SwitchStmt)
+		if len(n.Cases) != 0 {
+			st = psTop
+			for _, c := range n.Cases {
+				st = branchCombine(ffa.stateForList(c.Body), st)
+			}
+		}
+
+		st, fall := psTop, psNoInfo
+		for i := len(n.Cases) - 1; i >= 0; i-- {
+			cas := n.Cases[i]
+			cst := ffa.stateForList(cas.Body)
+			endsInFallthrough := false
+			if len(cas.Body) != 0 {
+				endsInFallthrough = cas.Body[0].Op() == ir.OFALL
+			}
+			if endsInFallthrough {
+				cst = blockCombine(cst, fall)
+			}
+			st = branchCombine(st, cst)
+			fall = cst
+		}
+	case ir.OFALL:
+		// Not important.
+	case ir.ODCLFUNC, ir.ORECOVER, ir.OAS, ir.OAS2, ir.OAS2FUNC, ir.OASOP,
+		ir.OPRINTLN, ir.OPRINT, ir.OLABEL, ir.OCALLINTER, ir.ODEFER,
+		ir.OSEND, ir.ORECV, ir.OSELRECV2, ir.OGO, ir.OAPPEND, ir.OAS2DOTTYPE,
+		ir.OAS2MAPR, ir.OGETG, ir.ODELETE, ir.OINLMARK, ir.OAS2RECV,
+		ir.OMIN, ir.OMAX, ir.OMAKE, ir.ORECOVERFP, ir.OGETCALLERSP:
+		// these should all be benign/uninteresting
+	case ir.OTAILCALL, ir.OJUMPTABLE, ir.OTYPESW:
+		// don't expect to see these at all.
+		base.Fatalf("unexpected op %s in func %s",
+			n.Op().String(), ir.FuncName(ffa.fn))
+	default:
+		base.Fatalf("%v: unhandled op %s in func %v",
+			ir.Line(n), n.Op().String(), ir.FuncName(ffa.fn))
+	}
+	if debugTrace&debugTraceFuncFlags != 0 {
+		fmt.Fprintf(os.Stderr, "=-= %v: visit n=%s returns %s\n",
+			ir.Line(n), n.Op().String(), st.String())
+	}
+	ffa.setState(n, st)
+}
+
+func (ffa *funcFlagsAnalyzer) nodeVisitPre(n ir.Node) {
+}

src/cmd/compile/internal/inline/inlheur/analyze_func_params.go

@@ -0,0 +1,355 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"cmd/compile/internal/ir"
+	"fmt"
+	"os"
+)
+
+// paramsAnalyzer holds state information for the phase that computes
+// flags for a Go functions parameters, for use in inline heuristics.
+// Note that the params slice below includes entries for blanks.
+type paramsAnalyzer struct {
+	fname  string
+	values []ParamPropBits
+	params []*ir.Name
+	top    []bool
+	*condLevelTracker
+	*nameFinder
+}
+
+// getParams returns an *ir.Name slice containing all params for the
+// function (plus rcvr as well if applicable).
+func getParams(fn *ir.Func) []*ir.Name {
+	sig := fn.Type()
+	numParams := sig.NumRecvs() + sig.NumParams()
+	return fn.Dcl[:numParams]
+}
+
+// addParamsAnalyzer creates a new paramsAnalyzer helper object for
+// the function fn, appends it to the analyzers list, and returns the
+// new list. If the function in question doesn't have any interesting
+// parameters then the analyzer list is returned unchanged, and the
+// params flags in "fp" are updated accordingly.
+func addParamsAnalyzer(fn *ir.Func, analyzers []propAnalyzer, fp *FuncProps, nf *nameFinder) []propAnalyzer {
+	pa, props := makeParamsAnalyzer(fn, nf)
+	if pa != nil {
+		analyzers = append(analyzers, pa)
+	} else {
+		fp.ParamFlags = props
+	}
+	return analyzers
+}
+
+// makeParamsAnalyzer creates a new helper object to analyze parameters
+// of function fn. If the function doesn't have any interesting
+// params, a nil helper is returned along with a set of default param
+// flags for the func.
+func makeParamsAnalyzer(fn *ir.Func, nf *nameFinder) (*paramsAnalyzer, []ParamPropBits) {
+	params := getParams(fn) // includes receiver if applicable
+	if len(params) == 0 {
+		return nil, nil
+	}
+	vals := make([]ParamPropBits, len(params))
+	if fn.Inl == nil {
+		return nil, vals
+	}
+	top := make([]bool, len(params))
+	interestingToAnalyze := false
+	for i, pn := range params {
+		if pn == nil {
+			continue
+		}
+		pt := pn.Type()
+		if !pt.IsScalar() && !pt.HasNil() {
+			// existing properties not applicable here (for things
+			// like structs, arrays, slices, etc).
+			continue
+		}
+		// If param is reassigned, skip it.
+		if ir.Reassigned(pn) {
+			continue
+		}
+		top[i] = true
+		interestingToAnalyze = true
+	}
+	if !interestingToAnalyze {
+		return nil, vals
+	}
+
+	if debugTrace&debugTraceParams != 0 {
+		fmt.Fprintf(os.Stderr, "=-= param analysis of func %v:\n",
+			fn.Sym().Name)
+		for i := range vals {
+			n := "_"
+			if params[i] != nil {
+				n = params[i].Sym().String()
+			}
+			fmt.Fprintf(os.Stderr, "=-=  %d: %q %s top=%v\n",
+				i, n, vals[i].String(), top[i])
+		}
+	}
+	pa := &paramsAnalyzer{
+		fname:            fn.Sym().Name,
+		values:           vals,
+		params:           params,
+		top:              top,
+		condLevelTracker: new(condLevelTracker),
+		nameFinder:       nf,
+	}
+	return pa, nil
+}
+
+func (pa *paramsAnalyzer) setResults(funcProps *FuncProps) {
+	funcProps.ParamFlags = pa.values
+}
+
+func (pa *paramsAnalyzer) findParamIdx(n *ir.Name) int {
+	if n == nil {
+		panic("bad")
+	}
+	for i := range pa.params {
+		if pa.params[i] == n {
+			return i
+		}
+	}
+	return -1
+}
+
+type testfType func(x ir.Node, param *ir.Name, idx int) (bool, bool)
+
+// paramsAnalyzer invokes function 'testf' on the specified expression
+// 'x' for each parameter, and if the result is TRUE, or's 'flag' into
+// the flags for that param.
+func (pa *paramsAnalyzer) checkParams(x ir.Node, flag ParamPropBits, mayflag ParamPropBits, testf testfType) {
+	for idx, p := range pa.params {
+		if !pa.top[idx] && pa.values[idx] == ParamNoInfo {
+			continue
+		}
+		result, may := testf(x, p, idx)
+		if debugTrace&debugTraceParams != 0 {
+			fmt.Fprintf(os.Stderr, "=-= test expr %v param %s result=%v flag=%s\n", x, p.Sym().Name, result, flag.String())
+		}
+		if result {
+			v := flag
+			if pa.condLevel != 0 || may {
+				v = mayflag
+			}
+			pa.values[idx] |= v
+			pa.top[idx] = false
+		}
+	}
+}
+
+// foldCheckParams checks expression 'x' (an 'if' condition or
+// 'switch' stmt expr) to see if the expr would fold away if a
+// specific parameter had a constant value.
+func (pa *paramsAnalyzer) foldCheckParams(x ir.Node) {
+	pa.checkParams(x, ParamFeedsIfOrSwitch, ParamMayFeedIfOrSwitch,
+		func(x ir.Node, p *ir.Name, idx int) (bool, bool) {
+			return ShouldFoldIfNameConstant(x, []*ir.Name{p}), false
+		})
+}
+
+// callCheckParams examines the target of call expression 'ce' to see
+// if it is making a call to the value passed in for some parameter.
+func (pa *paramsAnalyzer) callCheckParams(ce *ir.CallExpr) {
+	switch ce.Op() {
+	case ir.OCALLINTER:
+		if ce.Op() != ir.OCALLINTER {
+			return
+		}
+		sel := ce.Fun.(*ir.SelectorExpr)
+		r := pa.staticValue(sel.X)
+		if r.Op() != ir.ONAME {
+			return
+		}
+		name := r.(*ir.Name)
+		if name.Class != ir.PPARAM {
+			return
+		}
+		pa.checkParams(r, ParamFeedsInterfaceMethodCall,
+			ParamMayFeedInterfaceMethodCall,
+			func(x ir.Node, p *ir.Name, idx int) (bool, bool) {
+				name := x.(*ir.Name)
+				return name == p, false
+			})
+	case ir.OCALLFUNC:
+		if ce.Fun.Op() != ir.ONAME {
+			return
+		}
+		called := ir.StaticValue(ce.Fun)
+		if called.Op() != ir.ONAME {
+			return
+		}
+		name := called.(*ir.Name)
+		if name.Class == ir.PPARAM {
+			pa.checkParams(called, ParamFeedsIndirectCall,
+				ParamMayFeedIndirectCall,
+				func(x ir.Node, p *ir.Name, idx int) (bool, bool) {
+					name := x.(*ir.Name)
+					return name == p, false
+				})
+		} else {
+			cname := pa.funcName(called)
+			if cname != nil {
+				pa.deriveFlagsFromCallee(ce, cname.Func)
+			}
+		}
+	}
+}
+
+// deriveFlagsFromCallee tries to derive flags for the current
+// function based on a call this function makes to some other
+// function. Example:
+//
+//	/* Simple */                /* Derived from callee */
+//	func foo(f func(int)) {     func foo(f func(int)) {
+//	  f(2)                        bar(32, f)
+//	}                           }
+//	                            func bar(x int, f func()) {
+//	                              f(x)
+//	                            }
+//
+// Here we can set the "param feeds indirect call" flag for
+// foo's param 'f' since we know that bar has that flag set for
+// its second param, and we're passing that param a function.
+func (pa *paramsAnalyzer) deriveFlagsFromCallee(ce *ir.CallExpr, callee *ir.Func) {
+	calleeProps := propsForFunc(callee)
+	if calleeProps == nil {
+		return
+	}
+	if debugTrace&debugTraceParams != 0 {
+		fmt.Fprintf(os.Stderr, "=-= callee props for %v:\n%s",
+			callee.Sym().Name, calleeProps.String())
+	}
+
+	must := []ParamPropBits{ParamFeedsInterfaceMethodCall, ParamFeedsIndirectCall, ParamFeedsIfOrSwitch}
+	may := []ParamPropBits{ParamMayFeedInterfaceMethodCall, ParamMayFeedIndirectCall, ParamMayFeedIfOrSwitch}
+
+	for pidx, arg := range ce.Args {
+		// Does the callee param have any interesting properties?
+		// If not we can skip this one.
+		pflag := calleeProps.ParamFlags[pidx]
+		if pflag == 0 {
+			continue
+		}
+		// See if one of the caller's parameters is flowing unmodified
+		// into this actual expression.
+		r := pa.staticValue(arg)
+		if r.Op() != ir.ONAME {
+			return
+		}
+		name := r.(*ir.Name)
+		if name.Class != ir.PPARAM {
+			return
+		}
+		callerParamIdx := pa.findParamIdx(name)
+		// note that callerParamIdx may return -1 in the case where
+		// the param belongs not to the current closure func we're
+		// analyzing but to an outer enclosing func.
+		if callerParamIdx == -1 {
+			return
+		}
+		if pa.params[callerParamIdx] == nil {
+			panic("something went wrong")
+		}
+		if !pa.top[callerParamIdx] &&
+			pa.values[callerParamIdx] == ParamNoInfo {
+			continue
+		}
+		if debugTrace&debugTraceParams != 0 {
+			fmt.Fprintf(os.Stderr, "=-= pflag for arg %d is %s\n",
+				pidx, pflag.String())
+		}
+		for i := range must {
+			mayv := may[i]
+			mustv := must[i]
+			if pflag&mustv != 0 && pa.condLevel == 0 {
+				pa.values[callerParamIdx] |= mustv
+			} else if pflag&(mustv|mayv) != 0 {
+				pa.values[callerParamIdx] |= mayv
+			}
+		}
+		pa.top[callerParamIdx] = false
+	}
+}
+
+func (pa *paramsAnalyzer) nodeVisitPost(n ir.Node) {
+	if len(pa.values) == 0 {
+		return
+	}
+	pa.condLevelTracker.post(n)
+	switch n.Op() {
+	case ir.OCALLFUNC:
+		ce := n.(*ir.CallExpr)
+		pa.callCheckParams(ce)
+	case ir.OCALLINTER:
+		ce := n.(*ir.CallExpr)
+		pa.callCheckParams(ce)
+	case ir.OIF:
+		ifst := n.(*ir.IfStmt)
+		pa.foldCheckParams(ifst.Cond)
+	case ir.OSWITCH:
+		swst := n.(*ir.SwitchStmt)
+		if swst.Tag != nil {
+			pa.foldCheckParams(swst.Tag)
+		}
+	}
+}
+
+func (pa *paramsAnalyzer) nodeVisitPre(n ir.Node) {
+	if len(pa.values) == 0 {
+		return
+	}
+	pa.condLevelTracker.pre(n)
+}
+
+// condLevelTracker helps keeps track very roughly of "level of conditional
+// nesting", e.g. how many "if" statements you have to go through to
+// get to the point where a given stmt executes. Example:
+//
+//	                      cond nesting level
+//	func foo() {
+//	 G = 1                   0
+//	 if x < 10 {             0
+//	  if y < 10 {            1
+//	   G = 0                 2
+//	  }
+//	 }
+//	}
+//
+// The intent here is to provide some sort of very abstract relative
+// hotness metric, e.g. "G = 1" above is expected to be executed more
+// often than "G = 0" (in the aggregate, across large numbers of
+// functions).
+type condLevelTracker struct {
+	condLevel int
+}
+
+func (c *condLevelTracker) pre(n ir.Node) {
+	// Increment level of "conditional testing" if we see
+	// an "if" or switch statement, and decrement if in
+	// a loop.
+	switch n.Op() {
+	case ir.OIF, ir.OSWITCH:
+		c.condLevel++
+	case ir.OFOR, ir.ORANGE:
+		c.condLevel--
+	}
+}
+
+func (c *condLevelTracker) post(n ir.Node) {
+	switch n.Op() {
+	case ir.OFOR, ir.ORANGE:
+		c.condLevel++
+	case ir.OIF:
+		c.condLevel--
+	case ir.OSWITCH:
+		c.condLevel--
+	}
+}

src/cmd/compile/internal/inline/inlheur/analyze_func_returns.go

@@ -0,0 +1,277 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"cmd/compile/internal/ir"
+	"fmt"
+	"go/constant"
+	"go/token"
+	"os"
+)
+
+// resultsAnalyzer stores state information for the process of
+// computing flags/properties for the return values of a specific Go
+// function, as part of inline heuristics synthesis.
+type resultsAnalyzer struct {
+	fname           string
+	props           []ResultPropBits
+	values          []resultVal
+	inlineMaxBudget int
+	*nameFinder
+}
+
+// resultVal captures information about a specific result returned from
+// the function we're analyzing; we are interested in cases where
+// the func always returns the same constant, or always returns
+// the same function, etc. This container stores info on a the specific
+// scenarios we're looking for.
+type resultVal struct {
+	cval    constant.Value
+	fn      *ir.Name
+	fnClo   bool
+	top     bool
+	derived bool // see deriveReturnFlagsFromCallee below
+}
+
+// addResultsAnalyzer creates a new resultsAnalyzer helper object for
+// the function fn, appends it to the analyzers list, and returns the
+// new list. If the function in question doesn't have any returns (or
+// any interesting returns) then the analyzer list is left as is, and
+// the result flags in "fp" are updated accordingly.
+func addResultsAnalyzer(fn *ir.Func, analyzers []propAnalyzer, fp *FuncProps, inlineMaxBudget int, nf *nameFinder) []propAnalyzer {
+	ra, props := makeResultsAnalyzer(fn, inlineMaxBudget, nf)
+	if ra != nil {
+		analyzers = append(analyzers, ra)
+	} else {
+		fp.ResultFlags = props
+	}
+	return analyzers
+}
+
+// makeResultsAnalyzer creates a new helper object to analyze results
+// in function fn. If the function doesn't have any interesting
+// results, a nil helper is returned along with a set of default
+// result flags for the func.
+func makeResultsAnalyzer(fn *ir.Func, inlineMaxBudget int, nf *nameFinder) (*resultsAnalyzer, []ResultPropBits) {
+	results := fn.Type().Results()
+	if len(results) == 0 {
+		return nil, nil
+	}
+	props := make([]ResultPropBits, len(results))
+	if fn.Inl == nil {
+		return nil, props
+	}
+	vals := make([]resultVal, len(results))
+	interestingToAnalyze := false
+	for i := range results {
+		rt := results[i].Type
+		if !rt.IsScalar() && !rt.HasNil() {
+			// existing properties not applicable here (for things
+			// like structs, arrays, slices, etc).
+			continue
+		}
+		// set the "top" flag (as in "top element of data flow lattice")
+		// meaning "we have no info yet, but we might later on".
+		vals[i].top = true
+		interestingToAnalyze = true
+	}
+	if !interestingToAnalyze {
+		return nil, props
+	}
+	ra := &resultsAnalyzer{
+		props:           props,
+		values:          vals,
+		inlineMaxBudget: inlineMaxBudget,
+		nameFinder:      nf,
+	}
+	return ra, nil
+}
+
+// setResults transfers the calculated result properties for this
+// function to 'funcProps'.
+func (ra *resultsAnalyzer) setResults(funcProps *FuncProps) {
+	// Promote ResultAlwaysSameFunc to ResultAlwaysSameInlinableFunc
+	for i := range ra.values {
+		if ra.props[i] == ResultAlwaysSameFunc && !ra.values[i].derived {
+			f := ra.values[i].fn.Func
+			// HACK: in order to allow for call site score
+			// adjustments, we used a relaxed inline budget in
+			// determining inlinability. For the check below, however,
+			// we want to know is whether the func in question is
+			// likely to be inlined, as opposed to whether it might
+			// possibly be inlined if all the right score adjustments
+			// happened, so do a simple check based on the cost.
+			if f.Inl != nil && f.Inl.Cost <= int32(ra.inlineMaxBudget) {
+				ra.props[i] = ResultAlwaysSameInlinableFunc
+			}
+		}
+	}
+	funcProps.ResultFlags = ra.props
+}
+
+func (ra *resultsAnalyzer) pessimize() {
+	for i := range ra.props {
+		ra.props[i] = ResultNoInfo
+	}
+}
+
+func (ra *resultsAnalyzer) nodeVisitPre(n ir.Node) {
+}
+
+func (ra *resultsAnalyzer) nodeVisitPost(n ir.Node) {
+	if len(ra.values) == 0 {
+		return
+	}
+	if n.Op() != ir.ORETURN {
+		return
+	}
+	if debugTrace&debugTraceResults != 0 {
+		fmt.Fprintf(os.Stderr, "=+= returns nodevis %v %s\n",
+			ir.Line(n), n.Op().String())
+	}
+
+	// No support currently for named results, so if we see an empty
+	// "return" stmt, be conservative.
+	rs := n.(*ir.ReturnStmt)
+	if len(rs.Results) != len(ra.values) {
+		ra.pessimize()
+		return
+	}
+	for i, r := range rs.Results {
+		ra.analyzeResult(i, r)
+	}
+}
+
+// analyzeResult examines the expression 'n' being returned as the
+// 'ii'th argument in some return statement to see whether has
+// interesting characteristics (for example, returns a constant), then
+// applies a dataflow "meet" operation to combine this result with any
+// previous result (for the given return slot) that we've already
+// processed.
+func (ra *resultsAnalyzer) analyzeResult(ii int, n ir.Node) {
+	isAllocMem := ra.isAllocatedMem(n)
+	isConcConvItf := ra.isConcreteConvIface(n)
+	constVal := ra.constValue(n)
+	isConst := (constVal != nil)
+	isNil := ra.isNil(n)
+	rfunc := ra.funcName(n)
+	isFunc := (rfunc != nil)
+	isClo := (rfunc != nil && rfunc.Func.OClosure != nil)
+	curp := ra.props[ii]
+	dprops, isDerivedFromCall := ra.deriveReturnFlagsFromCallee(n)
+	newp := ResultNoInfo
+	var newcval constant.Value
+	var newfunc *ir.Name
+
+	if debugTrace&debugTraceResults != 0 {
+		fmt.Fprintf(os.Stderr, "=-= %v: analyzeResult n=%s ismem=%v isconcconv=%v isconst=%v isnil=%v isfunc=%v isclo=%v\n", ir.Line(n), n.Op().String(), isAllocMem, isConcConvItf, isConst, isNil, isFunc, isClo)
+	}
+
+	if ra.values[ii].top {
+		ra.values[ii].top = false
+		// this is the first return we've seen; record
+		// whatever properties it has.
+		switch {
+		case isAllocMem:
+			newp = ResultIsAllocatedMem
+		case isConcConvItf:
+			newp = ResultIsConcreteTypeConvertedToInterface
+		case isFunc:
+			newp = ResultAlwaysSameFunc
+			newfunc = rfunc
+		case isConst:
+			newp = ResultAlwaysSameConstant
+			newcval = constVal
+		case isNil:
+			newp = ResultAlwaysSameConstant
+			newcval = nil
+		case isDerivedFromCall:
+			newp = dprops
+			ra.values[ii].derived = true
+		}
+	} else {
+		if !ra.values[ii].derived {
+			// this is not the first return we've seen; apply
+			// what amounts of a "meet" operator to combine
+			// the properties we see here with what we saw on
+			// the previous returns.
+			switch curp {
+			case ResultIsAllocatedMem:
+				if isAllocMem {
+					newp = ResultIsAllocatedMem
+				}
+			case ResultIsConcreteTypeConvertedToInterface:
+				if isConcConvItf {
+					newp = ResultIsConcreteTypeConvertedToInterface
+				}
+			case ResultAlwaysSameConstant:
+				if isNil && ra.values[ii].cval == nil {
+					newp = ResultAlwaysSameConstant
+					newcval = nil
+				} else if isConst && constant.Compare(constVal, token.EQL, ra.values[ii].cval) {
+					newp = ResultAlwaysSameConstant
+					newcval = constVal
+				}
+			case ResultAlwaysSameFunc:
+				if isFunc && isSameFuncName(rfunc, ra.values[ii].fn) {
+					newp = ResultAlwaysSameFunc
+					newfunc = rfunc
+				}
+			}
+		}
+	}
+	ra.values[ii].fn = newfunc
+	ra.values[ii].fnClo = isClo
+	ra.values[ii].cval = newcval
+	ra.props[ii] = newp
+
+	if debugTrace&debugTraceResults != 0 {
+		fmt.Fprintf(os.Stderr, "=-= %v: analyzeResult newp=%s\n",
+			ir.Line(n), newp)
+	}
+}
+
+// deriveReturnFlagsFromCallee tries to set properties for a given
+// return result where we're returning call expression; return value
+// is a return property value and a boolean indicating whether the
+// prop is valid. Examples:
+//
+//	func foo() int { return bar() }
+//	func bar() int { return 42 }
+//	func blix() int { return 43 }
+//	func two(y int) int {
+//	  if y < 0 { return bar() } else { return blix() }
+//	}
+//
+// Since "foo" always returns the result of a call to "bar", we can
+// set foo's return property to that of bar. In the case of "two", however,
+// even though each return path returns a constant, we don't know
+// whether the constants are identical, hence we need to be conservative.
+func (ra *resultsAnalyzer) deriveReturnFlagsFromCallee(n ir.Node) (ResultPropBits, bool) {
+	if n.Op() != ir.OCALLFUNC {
+		return 0, false
+	}
+	ce := n.(*ir.CallExpr)
+	if ce.Fun.Op() != ir.ONAME {
+		return 0, false
+	}
+	called := ir.StaticValue(ce.Fun)
+	if called.Op() != ir.ONAME {
+		return 0, false
+	}
+	cname := ra.funcName(called)
+	if cname == nil {
+		return 0, false
+	}
+	calleeProps := propsForFunc(cname.Func)
+	if calleeProps == nil {
+		return 0, false
+	}
+	if len(calleeProps.ResultFlags) != 1 {
+		return 0, false
+	}
+	return calleeProps.ResultFlags[0], true
+}

src/cmd/compile/internal/inline/inlheur/callsite.go

@@ -0,0 +1,149 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/internal/src"
+	"fmt"
+	"io"
+	"path/filepath"
+	"sort"
+	"strings"
+)
+
+// CallSite records useful information about a potentially inlinable
+// (direct) function call. "Callee" is the target of the call, "Call"
+// is the ir node corresponding to the call itself, "Assign" is
+// the top-level assignment statement containing the call (if the call
+// appears in the form of a top-level statement, e.g. "x := foo()"),
+// "Flags" contains properties of the call that might be useful for
+// making inlining decisions, "Score" is the final score assigned to
+// the site, and "ID" is a numeric ID for the site within its
+// containing function.
+type CallSite struct {
+	Callee *ir.Func
+	Call   *ir.CallExpr
+	parent *CallSite
+	Assign ir.Node
+	Flags  CSPropBits
+
+	ArgProps  []ActualExprPropBits
+	Score     int
+	ScoreMask scoreAdjustTyp
+	ID        uint
+	aux       uint8
+}
+
+// CallSiteTab is a table of call sites, keyed by call expr.
+// Ideally it would be nice to key the table by src.XPos, but
+// this results in collisions for calls on very long lines (the
+// front end saturates column numbers at 255). We also wind up
+// with many calls that share the same auto-generated pos.
+type CallSiteTab map[*ir.CallExpr]*CallSite
+
+// ActualExprPropBits describes a property of an actual expression (value
+// passed to some specific func argument at a call site).
+type ActualExprPropBits uint8
+
+const (
+	ActualExprConstant ActualExprPropBits = 1 << iota
+	ActualExprIsConcreteConvIface
+	ActualExprIsFunc
+	ActualExprIsInlinableFunc
+)
+
+type CSPropBits uint32
+
+const (
+	CallSiteInLoop CSPropBits = 1 << iota
+	CallSiteOnPanicPath
+	CallSiteInInitFunc
+)
+
+type csAuxBits uint8
+
+const (
+	csAuxInlined = 1 << iota
+)
+
+// encodedCallSiteTab is a table keyed by "encoded" callsite
+// (stringified src.XPos plus call site ID) mapping to a value of call
+// property bits and score.
+type encodedCallSiteTab map[string]propsAndScore
+
+type propsAndScore struct {
+	props CSPropBits
+	score int
+	mask  scoreAdjustTyp
+}
+
+func (pas propsAndScore) String() string {
+	return fmt.Sprintf("P=%s|S=%d|M=%s", pas.props.String(),
+		pas.score, pas.mask.String())
+}
+
+func (cst CallSiteTab) merge(other CallSiteTab) error {
+	for k, v := range other {
+		if prev, ok := cst[k]; ok {
+			return fmt.Errorf("internal error: collision during call site table merge, fn=%s callsite=%s", prev.Callee.Sym().Name, fmtFullPos(prev.Call.Pos()))
+		}
+		cst[k] = v
+	}
+	return nil
+}
+
+func fmtFullPos(p src.XPos) string {
+	var sb strings.Builder
+	sep := ""
+	base.Ctxt.AllPos(p, func(pos src.Pos) {
+		fmt.Fprintf(&sb, sep)
+		sep = "|"
+		file := filepath.Base(pos.Filename())
+		fmt.Fprintf(&sb, "%s:%d:%d", file, pos.Line(), pos.Col())
+	})
+	return sb.String()
+}
+
+func EncodeCallSiteKey(cs *CallSite) string {
+	var sb strings.Builder
+	// FIXME: maybe rewrite line offsets relative to function start?
+	sb.WriteString(fmtFullPos(cs.Call.Pos()))
+	fmt.Fprintf(&sb, "|%d", cs.ID)
+	return sb.String()
+}
+
+func buildEncodedCallSiteTab(tab CallSiteTab) encodedCallSiteTab {
+	r := make(encodedCallSiteTab)
+	for _, cs := range tab {
+		k := EncodeCallSiteKey(cs)
+		r[k] = propsAndScore{
+			props: cs.Flags,
+			score: cs.Score,
+			mask:  cs.ScoreMask,
+		}
+	}
+	return r
+}
+
+// dumpCallSiteComments emits comments into the dump file for the
+// callsites in the function of interest. If "ecst" is non-nil, we use
+// that, otherwise generated a fresh encodedCallSiteTab from "tab".
+func dumpCallSiteComments(w io.Writer, tab CallSiteTab, ecst encodedCallSiteTab) {
+	if ecst == nil {
+		ecst = buildEncodedCallSiteTab(tab)
+	}
+	tags := make([]string, 0, len(ecst))
+	for k := range ecst {
+		tags = append(tags, k)
+	}
+	sort.Strings(tags)
+	for _, s := range tags {
+		v := ecst[s]
+		fmt.Fprintf(w, "// callsite: %s flagstr %q flagval %d score %d mask %d maskstr %q\n", s, v.props.String(), v.props, v.score, v.mask, v.mask.String())
+	}
+	fmt.Fprintf(w, "// %s\n", csDelimiter)
+}

src/cmd/compile/internal/inline/inlheur/cspropbits_string.go

@@ -0,0 +1,56 @@
+// Code generated by "stringer -bitset -type CSPropBits"; DO NOT EDIT.
+
+package inlheur
+
+import "strconv"
+import "bytes"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[CallSiteInLoop-1]
+	_ = x[CallSiteOnPanicPath-2]
+	_ = x[CallSiteInInitFunc-4]
+}
+
+var _CSPropBits_value = [...]uint64{
+	0x1, /* CallSiteInLoop */
+	0x2, /* CallSiteOnPanicPath */
+	0x4, /* CallSiteInInitFunc */
+}
+
+const _CSPropBits_name = "CallSiteInLoopCallSiteOnPanicPathCallSiteInInitFunc"
+
+var _CSPropBits_index = [...]uint8{0, 14, 33, 51}
+
+func (i CSPropBits) String() string {
+	var b bytes.Buffer
+
+	remain := uint64(i)
+	seen := false
+
+	for k, v := range _CSPropBits_value {
+		x := _CSPropBits_name[_CSPropBits_index[k]:_CSPropBits_index[k+1]]
+		if v == 0 {
+			if i == 0 {
+				b.WriteString(x)
+				return b.String()
+			}
+			continue
+		}
+		if (v & remain) == v {
+			remain &^= v
+			x := _CSPropBits_name[_CSPropBits_index[k]:_CSPropBits_index[k+1]]
+			if seen {
+				b.WriteString("|")
+			}
+			seen = true
+			b.WriteString(x)
+		}
+	}
+	if remain == 0 {
+		return b.String()
+	}
+	return "CSPropBits(0x" + strconv.FormatInt(int64(i), 16) + ")"
+}

src/cmd/compile/internal/inline/inlheur/debugflags_test.go

@@ -0,0 +1,65 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"testing"
+)
+
+func TestInlScoreAdjFlagParse(t *testing.T) {
+	scenarios := []struct {
+		value string
+		expok bool
+	}{
+		{
+			value: "returnFeedsConcreteToInterfaceCallAdj:9",
+			expok: true,
+		},
+		{
+			value: "panicPathAdj:-1/initFuncAdj:9",
+			expok: true,
+		},
+		{
+			value: "",
+			expok: false,
+		},
+		{
+			value: "nonsenseAdj:10",
+			expok: false,
+		},
+		{
+			value: "inLoopAdj:",
+			expok: false,
+		},
+		{
+			value: "inLoopAdj:10:10",
+			expok: false,
+		},
+		{
+			value: "inLoopAdj:blah",
+			expok: false,
+		},
+		{
+			value: "/",
+			expok: false,
+		},
+	}
+
+	for _, scenario := range scenarios {
+		err := parseScoreAdj(scenario.value)
+		t.Logf("for value=%q err is %v\n", scenario.value, err)
+		if scenario.expok {
+			if err != nil {
+				t.Errorf("expected parseScoreAdj(%s) ok, got err %v",
+					scenario.value, err)
+			}
+		} else {
+			if err == nil {
+				t.Errorf("expected parseScoreAdj(%s) failure, got success",
+					scenario.value)
+			}
+		}
+	}
+}

src/cmd/compile/internal/inline/inlheur/dumpscores_test.go

@@ -0,0 +1,109 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"internal/testenv"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestDumpCallSiteScoreDump(t *testing.T) {
+	td := t.TempDir()
+	testenv.MustHaveGoBuild(t)
+
+	scenarios := []struct {
+		name               string
+		promoted           int
+		indirectlyPromoted int
+		demoted            int
+		unchanged          int
+	}{
+		{
+			name:               "dumpscores",
+			promoted:           1,
+			indirectlyPromoted: 1,
+			demoted:            1,
+			unchanged:          5,
+		},
+	}
+
+	for _, scen := range scenarios {
+		dumpfile, err := gatherInlCallSitesScoresForFile(t, scen.name, td)
+		if err != nil {
+			t.Fatalf("dumping callsite scores for %q: error %v", scen.name, err)
+		}
+		var lines []string
+		if content, err := os.ReadFile(dumpfile); err != nil {
+			t.Fatalf("reading dump %q: error %v", dumpfile, err)
+		} else {
+			lines = strings.Split(string(content), "\n")
+		}
+		prom, indprom, dem, unch := 0, 0, 0, 0
+		for _, line := range lines {
+			switch {
+			case strings.TrimSpace(line) == "":
+			case !strings.Contains(line, "|"):
+			case strings.HasPrefix(line, "#"):
+			case strings.Contains(line, "PROMOTED"):
+				prom++
+			case strings.Contains(line, "INDPROM"):
+				indprom++
+			case strings.Contains(line, "DEMOTED"):
+				dem++
+			default:
+				unch++
+			}
+		}
+		showout := false
+		if prom != scen.promoted {
+			t.Errorf("testcase %q, got %d promoted want %d promoted",
+				scen.name, prom, scen.promoted)
+			showout = true
+		}
+		if indprom != scen.indirectlyPromoted {
+			t.Errorf("testcase %q, got %d indirectly promoted want %d",
+				scen.name, indprom, scen.indirectlyPromoted)
+			showout = true
+		}
+		if dem != scen.demoted {
+			t.Errorf("testcase %q, got %d demoted want %d demoted",
+				scen.name, dem, scen.demoted)
+			showout = true
+		}
+		if unch != scen.unchanged {
+			t.Errorf("testcase %q, got %d unchanged want %d unchanged",
+				scen.name, unch, scen.unchanged)
+			showout = true
+		}
+		if showout {
+			t.Logf(">> dump output: %s", strings.Join(lines, "\n"))
+		}
+	}
+}
+
+// gatherInlCallSitesScoresForFile builds the specified testcase 'testcase'
+// from testdata/props passing the "-d=dumpinlcallsitescores=1"
+// compiler option, to produce a dump, then returns the path of the
+// newly created file.
+func gatherInlCallSitesScoresForFile(t *testing.T, testcase string, td string) (string, error) {
+	t.Helper()
+	gopath := "testdata/" + testcase + ".go"
+	outpath := filepath.Join(td, testcase+".a")
+	dumpfile := filepath.Join(td, testcase+".callsites.txt")
+	run := []string{testenv.GoToolPath(t), "build",
+		"-gcflags=-d=dumpinlcallsitescores=1", "-o", outpath, gopath}
+	out, err := testenv.Command(t, run[0], run[1:]...).CombinedOutput()
+	t.Logf("run: %+v\n", run)
+	if err != nil {
+		return "", err
+	}
+	if err := os.WriteFile(dumpfile, out, 0666); err != nil {
+		return "", err
+	}
+	return dumpfile, err
+}

src/cmd/compile/internal/inline/inlheur/eclassify.go

@@ -0,0 +1,247 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"cmd/compile/internal/ir"
+	"fmt"
+	"os"
+)
+
+// ShouldFoldIfNameConstant analyzes expression tree 'e' to see
+// whether it contains only combinations of simple references to all
+// of the names in 'names' with selected constants + operators. The
+// intent is to identify expression that could be folded away to a
+// constant if the value of 'n' were available. Return value is TRUE
+// if 'e' does look foldable given the value of 'n', and given that
+// 'e' actually makes reference to 'n'. Some examples where the type
+// of "n" is int64, type of "s" is string, and type of "p" is *byte:
+//
+//	Simple?		Expr
+//	yes			n<10
+//	yes			n*n-100
+//	yes			(n < 10 || n > 100) && (n >= 12 || n <= 99 || n != 101)
+//	yes			s == "foo"
+//	yes			p == nil
+//	no			n<foo()
+//	no			n<1 || n>m
+//	no			float32(n)<1.0
+//	no			*p == 1
+//	no			1 + 100
+//	no			1 / n
+//	no			1 + unsafe.Sizeof(n)
+//
+// To avoid complexities (e.g. nan, inf) we stay way from folding and
+// floating point or complex operations (integers, bools, and strings
+// only). We also try to be conservative about avoiding any operation
+// that might result in a panic at runtime, e.g. for "n" with type
+// int64:
+//
+//	1<<(n-9) < 100/(n<<9999)
+//
+// we would return FALSE due to the negative shift count and/or
+// potential divide by zero.
+func ShouldFoldIfNameConstant(n ir.Node, names []*ir.Name) bool {
+	cl := makeExprClassifier(names)
+	var doNode func(ir.Node) bool
+	doNode = func(n ir.Node) bool {
+		ir.DoChildren(n, doNode)
+		cl.Visit(n)
+		return false
+	}
+	doNode(n)
+	if cl.getdisp(n) != exprSimple {
+		return false
+	}
+	for _, v := range cl.names {
+		if !v {
+			return false
+		}
+	}
+	return true
+}
+
+// exprClassifier holds intermediate state about nodes within an
+// expression tree being analyzed by ShouldFoldIfNameConstant. Here
+// "name" is the name node passed in, and "disposition" stores the
+// result of classifying a given IR node.
+type exprClassifier struct {
+	names       map[*ir.Name]bool
+	disposition map[ir.Node]disp
+}
+
+type disp int
+
+const (
+	// no info on this expr
+	exprNoInfo disp = iota
+
+	// expr contains only literals
+	exprLiterals
+
+	// expr is legal combination of literals and specified names
+	exprSimple
+)
+
+func (d disp) String() string {
+	switch d {
+	case exprNoInfo:
+		return "noinfo"
+	case exprSimple:
+		return "simple"
+	case exprLiterals:
+		return "literals"
+	default:
+		return fmt.Sprintf("unknown<%d>", d)
+	}
+}
+
+func makeExprClassifier(names []*ir.Name) *exprClassifier {
+	m := make(map[*ir.Name]bool, len(names))
+	for _, n := range names {
+		m[n] = false
+	}
+	return &exprClassifier{
+		names:       m,
+		disposition: make(map[ir.Node]disp),
+	}
+}
+
+// Visit sets the classification for 'n' based on the previously
+// calculated classifications for n's children, as part of a bottom-up
+// walk over an expression tree.
+func (ec *exprClassifier) Visit(n ir.Node) {
+
+	ndisp := exprNoInfo
+
+	binparts := func(n ir.Node) (ir.Node, ir.Node) {
+		if lex, ok := n.(*ir.LogicalExpr); ok {
+			return lex.X, lex.Y
+		} else if bex, ok := n.(*ir.BinaryExpr); ok {
+			return bex.X, bex.Y
+		} else {
+			panic("bad")
+		}
+	}
+
+	t := n.Type()
+	if t == nil {
+		if debugTrace&debugTraceExprClassify != 0 {
+			fmt.Fprintf(os.Stderr, "=-= *** untyped op=%s\n",
+				n.Op().String())
+		}
+	} else if t.IsInteger() || t.IsString() || t.IsBoolean() || t.HasNil() {
+		switch n.Op() {
+		// FIXME: maybe add support for OADDSTR?
+		case ir.ONIL:
+			ndisp = exprLiterals
+
+		case ir.OLITERAL:
+			if _, ok := n.(*ir.BasicLit); ok {
+			} else {
+				panic("unexpected")
+			}
+			ndisp = exprLiterals
+
+		case ir.ONAME:
+			nn := n.(*ir.Name)
+			if _, ok := ec.names[nn]; ok {
+				ndisp = exprSimple
+				ec.names[nn] = true
+			} else {
+				sv := ir.StaticValue(n)
+				if sv.Op() == ir.ONAME {
+					nn = sv.(*ir.Name)
+				}
+				if _, ok := ec.names[nn]; ok {
+					ndisp = exprSimple
+					ec.names[nn] = true
+				}
+			}
+
+		case ir.ONOT,
+			ir.OPLUS,
+			ir.ONEG:
+			uex := n.(*ir.UnaryExpr)
+			ndisp = ec.getdisp(uex.X)
+
+		case ir.OEQ,
+			ir.ONE,
+			ir.OLT,
+			ir.OGT,
+			ir.OGE,
+			ir.OLE:
+			// compare ops
+			x, y := binparts(n)
+			ndisp = ec.dispmeet(x, y)
+			if debugTrace&debugTraceExprClassify != 0 {
+				fmt.Fprintf(os.Stderr, "=-= meet(%s,%s) = %s for op=%s\n",
+					ec.getdisp(x), ec.getdisp(y), ec.dispmeet(x, y),
+					n.Op().String())
+			}
+		case ir.OLSH,
+			ir.ORSH,
+			ir.ODIV,
+			ir.OMOD:
+			x, y := binparts(n)
+			if ec.getdisp(y) == exprLiterals {
+				ndisp = ec.dispmeet(x, y)
+			}
+
+		case ir.OADD,
+			ir.OSUB,
+			ir.OOR,
+			ir.OXOR,
+			ir.OMUL,
+			ir.OAND,
+			ir.OANDNOT,
+			ir.OANDAND,
+			ir.OOROR:
+			x, y := binparts(n)
+			if debugTrace&debugTraceExprClassify != 0 {
+				fmt.Fprintf(os.Stderr, "=-= meet(%s,%s) = %s for op=%s\n",
+					ec.getdisp(x), ec.getdisp(y), ec.dispmeet(x, y),
+					n.Op().String())
+			}
+			ndisp = ec.dispmeet(x, y)
+		}
+	}
+
+	if debugTrace&debugTraceExprClassify != 0 {
+		fmt.Fprintf(os.Stderr, "=-= op=%s disp=%v\n", n.Op().String(),
+			ndisp.String())
+	}
+
+	ec.disposition[n] = ndisp
+}
+
+func (ec *exprClassifier) getdisp(x ir.Node) disp {
+	if d, ok := ec.disposition[x]; ok {
+		return d
+	} else {
+		panic("missing node from disp table")
+	}
+}
+
+// dispmeet performs a "meet" operation on the data flow states of
+// node x and y (where the term "meet" is being drawn from traditional
+// lattice-theoretical data flow analysis terminology).
+func (ec *exprClassifier) dispmeet(x, y ir.Node) disp {
+	xd := ec.getdisp(x)
+	if xd == exprNoInfo {
+		return exprNoInfo
+	}
+	yd := ec.getdisp(y)
+	if yd == exprNoInfo {
+		return exprNoInfo
+	}
+	if xd == exprSimple || yd == exprSimple {
+		return exprSimple
+	}
+	if xd != exprLiterals || yd != exprLiterals {
+		panic("unexpected")
+	}
+	return exprLiterals
+}

src/cmd/compile/internal/inline/inlheur/funcprop_string.go

@@ -0,0 +1,44 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"fmt"
+	"strings"
+)
+
+func (fp *FuncProps) String() string {
+	return fp.ToString("")
+}
+
+func (fp *FuncProps) ToString(prefix string) string {
+	var sb strings.Builder
+	if fp.Flags != 0 {
+		fmt.Fprintf(&sb, "%sFlags %s\n", prefix, fp.Flags)
+	}
+	flagSliceToSB[ParamPropBits](&sb, fp.ParamFlags,
+		prefix, "ParamFlags")
+	flagSliceToSB[ResultPropBits](&sb, fp.ResultFlags,
+		prefix, "ResultFlags")
+	return sb.String()
+}
+
+func flagSliceToSB[T interface {
+	~uint32
+	String() string
+}](sb *strings.Builder, sl []T, prefix string, tag string) {
+	var sb2 strings.Builder
+	foundnz := false
+	fmt.Fprintf(&sb2, "%s%s\n", prefix, tag)
+	for i, e := range sl {
+		if e != 0 {
+			foundnz = true
+		}
+		fmt.Fprintf(&sb2, "%s  %d %s\n", prefix, i, e.String())
+	}
+	if foundnz {
+		sb.WriteString(sb2.String())
+	}
+}

src/cmd/compile/internal/inline/inlheur/funcpropbits_string.go

@@ -0,0 +1,58 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Code generated by "stringer -bitset -type FuncPropBits"; DO NOT EDIT.
+
+package inlheur
+
+import (
+	"bytes"
+	"strconv"
+)
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[FuncPropNeverReturns-1]
+}
+
+var _FuncPropBits_value = [...]uint64{
+	0x1, /* FuncPropNeverReturns */
+}
+
+const _FuncPropBits_name = "FuncPropNeverReturns"
+
+var _FuncPropBits_index = [...]uint8{0, 20}
+
+func (i FuncPropBits) String() string {
+	var b bytes.Buffer
+
+	remain := uint64(i)
+	seen := false
+
+	for k, v := range _FuncPropBits_value {
+		x := _FuncPropBits_name[_FuncPropBits_index[k]:_FuncPropBits_index[k+1]]
+		if v == 0 {
+			if i == 0 {
+				b.WriteString(x)
+				return b.String()
+			}
+			continue
+		}
+		if (v & remain) == v {
+			remain &^= v
+			x := _FuncPropBits_name[_FuncPropBits_index[k]:_FuncPropBits_index[k+1]]
+			if seen {
+				b.WriteString("|")
+			}
+			seen = true
+			b.WriteString(x)
+		}
+	}
+	if remain == 0 {
+		return b.String()
+	}
+	return "FuncPropBits(0x" + strconv.FormatInt(int64(i), 16) + ")"
+}

src/cmd/compile/internal/inline/inlheur/funcprops_test.go

@@ -0,0 +1,530 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"bufio"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"internal/testenv"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+)
+
+var remasterflag = flag.Bool("update-expected", false, "if true, generate updated golden results in testcases for all props tests")
+
+func TestFuncProperties(t *testing.T) {
+	td := t.TempDir()
+	// td = "/tmp/qqq"
+	// os.RemoveAll(td)
+	// os.Mkdir(td, 0777)
+	testenv.MustHaveGoBuild(t)
+
+	// NOTE: this testpoint has the unfortunate characteristic that it
+	// relies on the installed compiler, meaning that if you make
+	// changes to the inline heuristics code in your working copy and
+	// then run the test, it will test the installed compiler and not
+	// your local modifications. TODO: decide whether to convert this
+	// to building a fresh compiler on the fly, or using some other
+	// scheme.
+
+	testcases := []string{"funcflags", "returns", "params",
+		"acrosscall", "calls", "returns2"}
+	for _, tc := range testcases {
+		dumpfile, err := gatherPropsDumpForFile(t, tc, td)
+		if err != nil {
+			t.Fatalf("dumping func props for %q: error %v", tc, err)
+		}
+		// Read in the newly generated dump.
+		dentries, dcsites, derr := readDump(t, dumpfile)
+		if derr != nil {
+			t.Fatalf("reading func prop dump: %v", derr)
+		}
+		if *remasterflag {
+			updateExpected(t, tc, dentries, dcsites)
+			continue
+		}
+		// Generate expected dump.
+		epath, egerr := genExpected(td, tc)
+		if egerr != nil {
+			t.Fatalf("generating expected func prop dump: %v", egerr)
+		}
+		// Read in the expected result entries.
+		eentries, ecsites, eerr := readDump(t, epath)
+		if eerr != nil {
+			t.Fatalf("reading expected func prop dump: %v", eerr)
+		}
+		// Compare new vs expected.
+		n := len(dentries)
+		eidx := 0
+		for i := 0; i < n; i++ {
+			dentry := dentries[i]
+			dcst := dcsites[i]
+			if !interestingToCompare(dentry.fname) {
+				continue
+			}
+			if eidx >= len(eentries) {
+				t.Errorf("testcase %s missing expected entry for %s, skipping", tc, dentry.fname)
+				continue
+			}
+			eentry := eentries[eidx]
+			ecst := ecsites[eidx]
+			eidx++
+			if dentry.fname != eentry.fname {
+				t.Errorf("got fn %q wanted %q, skipping checks",
+					dentry.fname, eentry.fname)
+				continue
+			}
+			compareEntries(t, tc, &dentry, dcst, &eentry, ecst)
+		}
+	}
+}
+
+func propBitsToString[T interface{ String() string }](sl []T) string {
+	var sb strings.Builder
+	for i, f := range sl {
+		fmt.Fprintf(&sb, "%d: %s\n", i, f.String())
+	}
+	return sb.String()
+}
+
+func compareEntries(t *testing.T, tc string, dentry *fnInlHeur, dcsites encodedCallSiteTab, eentry *fnInlHeur, ecsites encodedCallSiteTab) {
+	dfp := dentry.props
+	efp := eentry.props
+	dfn := dentry.fname
+
+	// Compare function flags.
+	if dfp.Flags != efp.Flags {
+		t.Errorf("testcase %q: Flags mismatch for %q: got %s, wanted %s",
+			tc, dfn, dfp.Flags.String(), efp.Flags.String())
+	}
+	// Compare returns
+	rgot := propBitsToString[ResultPropBits](dfp.ResultFlags)
+	rwant := propBitsToString[ResultPropBits](efp.ResultFlags)
+	if rgot != rwant {
+		t.Errorf("testcase %q: Results mismatch for %q: got:\n%swant:\n%s",
+			tc, dfn, rgot, rwant)
+	}
+	// Compare receiver + params.
+	pgot := propBitsToString[ParamPropBits](dfp.ParamFlags)
+	pwant := propBitsToString[ParamPropBits](efp.ParamFlags)
+	if pgot != pwant {
+		t.Errorf("testcase %q: Params mismatch for %q: got:\n%swant:\n%s",
+			tc, dfn, pgot, pwant)
+	}
+	// Compare call sites.
+	for k, ve := range ecsites {
+		if vd, ok := dcsites[k]; !ok {
+			t.Errorf("testcase %q missing expected callsite %q in func %q", tc, k, dfn)
+			continue
+		} else {
+			if vd != ve {
+				t.Errorf("testcase %q callsite %q in func %q: got %+v want %+v",
+					tc, k, dfn, vd.String(), ve.String())
+			}
+		}
+	}
+	for k := range dcsites {
+		if _, ok := ecsites[k]; !ok {
+			t.Errorf("testcase %q unexpected extra callsite %q in func %q", tc, k, dfn)
+		}
+	}
+}
+
+type dumpReader struct {
+	s  *bufio.Scanner
+	t  *testing.T
+	p  string
+	ln int
+}
+
+// readDump reads in the contents of a dump file produced
+// by the "-d=dumpinlfuncprops=..." command line flag by the Go
+// compiler. It breaks the dump down into separate sections
+// by function, then deserializes each func section into a
+// fnInlHeur object and returns a slice of those objects.
+func readDump(t *testing.T, path string) ([]fnInlHeur, []encodedCallSiteTab, error) {
+	content, err := os.ReadFile(path)
+	if err != nil {
+		return nil, nil, err
+	}
+	dr := &dumpReader{
+		s:  bufio.NewScanner(strings.NewReader(string(content))),
+		t:  t,
+		p:  path,
+		ln: 1,
+	}
+	// consume header comment until preamble delimiter.
+	found := false
+	for dr.scan() {
+		if dr.curLine() == preambleDelimiter {
+			found = true
+			break
+		}
+	}
+	if !found {
+		return nil, nil, fmt.Errorf("malformed testcase file %s, missing preamble delimiter", path)
+	}
+	res := []fnInlHeur{}
+	csres := []encodedCallSiteTab{}
+	for {
+		dentry, dcst, err := dr.readEntry()
+		if err != nil {
+			t.Fatalf("reading func prop dump: %v", err)
+		}
+		if dentry.fname == "" {
+			break
+		}
+		res = append(res, dentry)
+		csres = append(csres, dcst)
+	}
+	return res, csres, nil
+}
+
+func (dr *dumpReader) scan() bool {
+	v := dr.s.Scan()
+	if v {
+		dr.ln++
+	}
+	return v
+}
+
+func (dr *dumpReader) curLine() string {
+	res := strings.TrimSpace(dr.s.Text())
+	if !strings.HasPrefix(res, "// ") {
+		dr.t.Fatalf("malformed line %s:%d, no comment: %s", dr.p, dr.ln, res)
+	}
+	return res[3:]
+}
+
+// readObjBlob reads in a series of commented lines until
+// it hits a delimiter, then returns the contents of the comments.
+func (dr *dumpReader) readObjBlob(delim string) (string, error) {
+	var sb strings.Builder
+	foundDelim := false
+	for dr.scan() {
+		line := dr.curLine()
+		if delim == line {
+			foundDelim = true
+			break
+		}
+		sb.WriteString(line + "\n")
+	}
+	if err := dr.s.Err(); err != nil {
+		return "", err
+	}
+	if !foundDelim {
+		return "", fmt.Errorf("malformed input %s, missing delimiter %q",
+			dr.p, delim)
+	}
+	return sb.String(), nil
+}
+
+// readEntry reads a single function's worth of material from
+// a file produced by the "-d=dumpinlfuncprops=..." command line
+// flag. It deserializes the json for the func properties and
+// returns the resulting properties and function name. EOF is
+// signaled by a nil FuncProps return (with no error
+func (dr *dumpReader) readEntry() (fnInlHeur, encodedCallSiteTab, error) {
+	var funcInlHeur fnInlHeur
+	var callsites encodedCallSiteTab
+	if !dr.scan() {
+		return funcInlHeur, callsites, nil
+	}
+	// first line contains info about function: file/name/line
+	info := dr.curLine()
+	chunks := strings.Fields(info)
+	funcInlHeur.file = chunks[0]
+	funcInlHeur.fname = chunks[1]
+	if _, err := fmt.Sscanf(chunks[2], "%d", &funcInlHeur.line); err != nil {
+		return funcInlHeur, callsites, fmt.Errorf("scanning line %q: %v", info, err)
+	}
+	// consume comments until and including delimiter
+	for {
+		if !dr.scan() {
+			break
+		}
+		if dr.curLine() == comDelimiter {
+			break
+		}
+	}
+
+	// Consume JSON for encoded props.
+	dr.scan()
+	line := dr.curLine()
+	fp := &FuncProps{}
+	if err := json.Unmarshal([]byte(line), fp); err != nil {
+		return funcInlHeur, callsites, err
+	}
+	funcInlHeur.props = fp
+
+	// Consume callsites.
+	callsites = make(encodedCallSiteTab)
+	for dr.scan() {
+		line := dr.curLine()
+		if line == csDelimiter {
+			break
+		}
+		// expected format: "// callsite: <expanded pos> flagstr <desc> flagval <flags> score <score> mask <scoremask> maskstr <scoremaskstring>"
+		fields := strings.Fields(line)
+		if len(fields) != 12 {
+			return funcInlHeur, nil, fmt.Errorf("malformed callsite (nf=%d) %s line %d: %s", len(fields), dr.p, dr.ln, line)
+		}
+		if fields[2] != "flagstr" || fields[4] != "flagval" || fields[6] != "score" || fields[8] != "mask" || fields[10] != "maskstr" {
+			return funcInlHeur, nil, fmt.Errorf("malformed callsite %s line %d: %s",
+				dr.p, dr.ln, line)
+		}
+		tag := fields[1]
+		flagstr := fields[5]
+		flags, err := strconv.Atoi(flagstr)
+		if err != nil {
+			return funcInlHeur, nil, fmt.Errorf("bad flags val %s line %d: %q err=%v",
+				dr.p, dr.ln, line, err)
+		}
+		scorestr := fields[7]
+		score, err2 := strconv.Atoi(scorestr)
+		if err2 != nil {
+			return funcInlHeur, nil, fmt.Errorf("bad score val %s line %d: %q err=%v",
+				dr.p, dr.ln, line, err2)
+		}
+		maskstr := fields[9]
+		mask, err3 := strconv.Atoi(maskstr)
+		if err3 != nil {
+			return funcInlHeur, nil, fmt.Errorf("bad mask val %s line %d: %q err=%v",
+				dr.p, dr.ln, line, err3)
+		}
+		callsites[tag] = propsAndScore{
+			props: CSPropBits(flags),
+			score: score,
+			mask:  scoreAdjustTyp(mask),
+		}
+	}
+
+	// Consume function delimiter.
+	dr.scan()
+	line = dr.curLine()
+	if line != fnDelimiter {
+		return funcInlHeur, nil, fmt.Errorf("malformed testcase file %q, missing delimiter %q", dr.p, fnDelimiter)
+	}
+
+	return funcInlHeur, callsites, nil
+}
+
+// gatherPropsDumpForFile builds the specified testcase 'testcase' from
+// testdata/props passing the "-d=dumpinlfuncprops=..." compiler option,
+// to produce a properties dump, then returns the path of the newly
+// created file. NB: we can't use "go tool compile" here, since
+// some of the test cases import stdlib packages (such as "os").
+// This means using "go build", which is problematic since the
+// Go command can potentially cache the results of the compile step,
+// causing the test to fail when being run interactively. E.g.
+//
+//	$ rm -f dump.txt
+//	$ go build -o foo.a -gcflags=-d=dumpinlfuncprops=dump.txt foo.go
+//	$ rm -f dump.txt foo.a
+//	$ go build -o foo.a -gcflags=-d=dumpinlfuncprops=dump.txt foo.go
+//	$ ls foo.a dump.txt > /dev/null
+//	ls : cannot access 'dump.txt': No such file or directory
+//	$
+//
+// For this reason, pick a unique filename for the dump, so as to
+// defeat the caching.
+func gatherPropsDumpForFile(t *testing.T, testcase string, td string) (string, error) {
+	t.Helper()
+	gopath := "testdata/props/" + testcase + ".go"
+	outpath := filepath.Join(td, testcase+".a")
+	salt := fmt.Sprintf(".p%dt%d", os.Getpid(), time.Now().UnixNano())
+	dumpfile := filepath.Join(td, testcase+salt+".dump.txt")
+	run := []string{testenv.GoToolPath(t), "build",
+		"-gcflags=-d=dumpinlfuncprops=" + dumpfile, "-o", outpath, gopath}
+	out, err := testenv.Command(t, run[0], run[1:]...).CombinedOutput()
+	if err != nil {
+		t.Logf("compile command: %+v", run)
+	}
+	if strings.TrimSpace(string(out)) != "" {
+		t.Logf("%s", out)
+	}
+	return dumpfile, err
+}
+
+// genExpected reads in a given Go testcase file, strips out all the
+// unindented (column 0) commands, writes them out to a new file, and
+// returns the path of that new file. By picking out just the comments
+// from the Go file we wind up with something that resembles the
+// output from a "-d=dumpinlfuncprops=..." compilation.
+func genExpected(td string, testcase string) (string, error) {
+	epath := filepath.Join(td, testcase+".expected")
+	outf, err := os.OpenFile(epath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
+	if err != nil {
+		return "", err
+	}
+	gopath := "testdata/props/" + testcase + ".go"
+	content, err := os.ReadFile(gopath)
+	if err != nil {
+		return "", err
+	}
+	lines := strings.Split(string(content), "\n")
+	for _, line := range lines[3:] {
+		if !strings.HasPrefix(line, "// ") {
+			continue
+		}
+		fmt.Fprintf(outf, "%s\n", line)
+	}
+	if err := outf.Close(); err != nil {
+		return "", err
+	}
+	return epath, nil
+}
+
+type upexState struct {
+	dentries   []fnInlHeur
+	newgolines []string
+	atline     map[uint]uint
+}
+
+func mkUpexState(dentries []fnInlHeur) *upexState {
+	atline := make(map[uint]uint)
+	for _, e := range dentries {
+		atline[e.line] = atline[e.line] + 1
+	}
+	return &upexState{
+		dentries: dentries,
+		atline:   atline,
+	}
+}
+
+// updateExpected takes a given Go testcase file X.go and writes out a
+// new/updated version of the file to X.go.new, where the column-0
+// "expected" comments have been updated using fresh data from
+// "dentries".
+//
+// Writing of expected results is complicated by closures and by
+// generics, where you can have multiple functions that all share the
+// same starting line. Currently we combine up all the dups and
+// closures into the single pre-func comment.
+func updateExpected(t *testing.T, testcase string, dentries []fnInlHeur, dcsites []encodedCallSiteTab) {
+	nd := len(dentries)
+
+	ues := mkUpexState(dentries)
+
+	gopath := "testdata/props/" + testcase + ".go"
+	newgopath := "testdata/props/" + testcase + ".go.new"
+
+	// Read the existing Go file.
+	content, err := os.ReadFile(gopath)
+	if err != nil {
+		t.Fatalf("opening %s: %v", gopath, err)
+	}
+	golines := strings.Split(string(content), "\n")
+
+	// Preserve copyright.
+	ues.newgolines = append(ues.newgolines, golines[:4]...)
+	if !strings.HasPrefix(golines[0], "// Copyright") {
+		t.Fatalf("missing copyright from existing testcase")
+	}
+	golines = golines[4:]
+
+	clore := regexp.MustCompile(`.+\.func\d+[\.\d]*$`)
+
+	emitFunc := func(e *fnInlHeur, dcsites encodedCallSiteTab,
+		instance, atl uint) {
+		var sb strings.Builder
+		dumpFnPreamble(&sb, e, dcsites, instance, atl)
+		ues.newgolines = append(ues.newgolines,
+			strings.Split(strings.TrimSpace(sb.String()), "\n")...)
+	}
+
+	// Write file preamble with "DO NOT EDIT" message and such.
+	var sb strings.Builder
+	dumpFilePreamble(&sb)
+	ues.newgolines = append(ues.newgolines,
+		strings.Split(strings.TrimSpace(sb.String()), "\n")...)
+
+	// Helper to add a clump of functions to the output file.
+	processClump := func(idx int, emit bool) int {
+		// Process func itself, plus anything else defined
+		// on the same line
+		atl := ues.atline[dentries[idx].line]
+		for k := uint(0); k < atl; k++ {
+			if emit {
+				emitFunc(&dentries[idx], dcsites[idx], k, atl)
+			}
+			idx++
+		}
+		// now process any closures it contains
+		ncl := 0
+		for idx < nd {
+			nfn := dentries[idx].fname
+			if !clore.MatchString(nfn) {
+				break
+			}
+			ncl++
+			if emit {
+				emitFunc(&dentries[idx], dcsites[idx], 0, 1)
+			}
+			idx++
+		}
+		return idx
+	}
+
+	didx := 0
+	for _, line := range golines {
+		if strings.HasPrefix(line, "func ") {
+
+			// We have a function definition.
+			// Pick out the corresponding entry or entries in the dump
+			// and emit if interesting (or skip if not).
+			dentry := dentries[didx]
+			emit := interestingToCompare(dentry.fname)
+			didx = processClump(didx, emit)
+		}
+
+		// Consume all existing comments.
+		if strings.HasPrefix(line, "//") {
+			continue
+		}
+		ues.newgolines = append(ues.newgolines, line)
+	}
+
+	if didx != nd {
+		t.Logf("didx=%d wanted %d", didx, nd)
+	}
+
+	// Open new Go file and write contents.
+	of, err := os.OpenFile(newgopath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
+	if err != nil {
+		t.Fatalf("opening %s: %v", newgopath, err)
+	}
+	fmt.Fprintf(of, "%s", strings.Join(ues.newgolines, "\n"))
+	if err := of.Close(); err != nil {
+		t.Fatalf("closing %s: %v", newgopath, err)
+	}
+
+	t.Logf("update-expected: emitted updated file %s", newgopath)
+	t.Logf("please compare the two files, then overwrite %s with %s\n",
+		gopath, newgopath)
+}
+
+// interestingToCompare returns TRUE if we want to compare results
+// for function 'fname'.
+func interestingToCompare(fname string) bool {
+	if strings.HasPrefix(fname, "init.") {
+		return true
+	}
+	if strings.HasPrefix(fname, "T_") {
+		return true
+	}
+	f := strings.Split(fname, ".")
+	if len(f) == 2 && strings.HasPrefix(f[1], "T_") {
+		return true
+	}
+	return false
+}

src/cmd/compile/internal/inline/inlheur/function_properties.go

@@ -0,0 +1,98 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+// This file defines a set of Go function "properties" intended to
+// guide inlining heuristics; these properties may apply to the
+// function as a whole, or to one or more function return values or
+// parameters.
+//
+// IMPORTANT: function properties are produced on a "best effort"
+// basis, meaning that the code that computes them doesn't verify that
+// the properties are guaranteed to be true in 100% of cases. For this
+// reason, properties should only be used to drive always-safe
+// optimization decisions (e.g. "should I inline this call", or
+// "should I unroll this loop") as opposed to potentially unsafe IR
+// alterations that could change program semantics (e.g. "can I delete
+// this variable" or "can I move this statement to a new location").
+//
+//----------------------------------------------------------------
+
+// FuncProps describes a set of function or method properties that may
+// be useful for inlining heuristics. Here 'Flags' are properties that
+// we think apply to the entire function; 'RecvrParamFlags' are
+// properties of specific function params (or the receiver), and
+// 'ResultFlags' are things properties we think will apply to values
+// of specific results. Note that 'ParamFlags' includes and entry for
+// the receiver if applicable, and does include etries for blank
+// params; for a function such as "func foo(_ int, b byte, _ float32)"
+// the length of ParamFlags will be 3.
+type FuncProps struct {
+	Flags       FuncPropBits
+	ParamFlags  []ParamPropBits // slot 0 receiver if applicable
+	ResultFlags []ResultPropBits
+}
+
+type FuncPropBits uint32
+
+const (
+	// Function always panics or invokes os.Exit() or a func that does
+	// likewise.
+	FuncPropNeverReturns FuncPropBits = 1 << iota
+)
+
+type ParamPropBits uint32
+
+const (
+	// No info about this param
+	ParamNoInfo ParamPropBits = 0
+
+	// Parameter value feeds unmodified into a top-level interface
+	// call (this assumes the parameter is of interface type).
+	ParamFeedsInterfaceMethodCall ParamPropBits = 1 << iota
+
+	// Parameter value feeds unmodified into an interface call that
+	// may be conditional/nested and not always executed (this assumes
+	// the parameter is of interface type).
+	ParamMayFeedInterfaceMethodCall ParamPropBits = 1 << iota
+
+	// Parameter value feeds unmodified into a top level indirect
+	// function call (assumes parameter is of function type).
+	ParamFeedsIndirectCall
+
+	// Parameter value feeds unmodified into an indirect function call
+	// that is conditional/nested (not guaranteed to execute). Assumes
+	// parameter is of function type.
+	ParamMayFeedIndirectCall
+
+	// Parameter value feeds unmodified into a top level "switch"
+	// statement or "if" statement simple expressions (see more on
+	// "simple" expression classification below).
+	ParamFeedsIfOrSwitch
+
+	// Parameter value feeds unmodified into a "switch" or "if"
+	// statement simple expressions (see more on "simple" expression
+	// classification below), where the if/switch is
+	// conditional/nested.
+	ParamMayFeedIfOrSwitch
+)
+
+type ResultPropBits uint32
+
+const (
+	// No info about this result
+	ResultNoInfo ResultPropBits = 0
+	// This result always contains allocated memory.
+	ResultIsAllocatedMem ResultPropBits = 1 << iota
+	// This result is always a single concrete type that is
+	// implicitly converted to interface.
+	ResultIsConcreteTypeConvertedToInterface
+	// Result is always the same non-composite compile time constant.
+	ResultAlwaysSameConstant
+	// Result is always the same function or closure.
+	ResultAlwaysSameFunc
+	// Result is always the same (potentially) inlinable function or closure.
+	ResultAlwaysSameInlinableFunc
+)

src/cmd/compile/internal/inline/inlheur/names.go

@@ -0,0 +1,129 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"cmd/compile/internal/ir"
+	"go/constant"
+)
+
+// nameFinder provides a set of "isXXX" query methods for clients to
+// ask whether a given AST node corresponds to a function, a constant
+// value, and so on. These methods use an underlying ir.ReassignOracle
+// to return more precise results in cases where an "interesting"
+// value is assigned to a singly-defined local temp. Example:
+//
+//	const q = 101
+//	fq := func() int { return q }
+//	copyOfConstant := q
+//	copyOfFunc := f
+//	interestingCall(copyOfConstant, copyOfFunc)
+//
+// A name finder query method invoked on the arguments being passed to
+// "interestingCall" will be able detect that 'copyOfConstant' always
+// evaluates to a constant (even though it is in fact a PAUTO local
+// variable). A given nameFinder can also operate without using
+// ir.ReassignOracle (in cases where it is not practical to look
+// at the entire function); in such cases queries will still work
+// for explicit constant values and functions.
+type nameFinder struct {
+	ro *ir.ReassignOracle
+}
+
+// newNameFinder returns a new nameFinder object with a reassignment
+// oracle initialized based on the function fn, or if fn is nil,
+// without an underlying ReassignOracle.
+func newNameFinder(fn *ir.Func) *nameFinder {
+	var ro *ir.ReassignOracle
+	if fn != nil {
+		ro = &ir.ReassignOracle{}
+		ro.Init(fn)
+	}
+	return &nameFinder{ro: ro}
+}
+
+// funcName returns the *ir.Name for the func or method
+// corresponding to node 'n', or nil if n can't be proven
+// to contain a function value.
+func (nf *nameFinder) funcName(n ir.Node) *ir.Name {
+	sv := n
+	if nf.ro != nil {
+		sv = nf.ro.StaticValue(n)
+	}
+	if name := ir.StaticCalleeName(sv); name != nil {
+		return name
+	}
+	return nil
+}
+
+// isAllocatedMem returns true if node n corresponds to a memory
+// allocation expression (make, new, or equivalent).
+func (nf *nameFinder) isAllocatedMem(n ir.Node) bool {
+	sv := n
+	if nf.ro != nil {
+		sv = nf.ro.StaticValue(n)
+	}
+	switch sv.Op() {
+	case ir.OMAKESLICE, ir.ONEW, ir.OPTRLIT, ir.OSLICELIT:
+		return true
+	}
+	return false
+}
+
+// constValue returns the underlying constant.Value for an AST node n
+// if n is itself a constant value/expr, or if n is a singly assigned
+// local containing constant expr/value (or nil not constant).
+func (nf *nameFinder) constValue(n ir.Node) constant.Value {
+	sv := n
+	if nf.ro != nil {
+		sv = nf.ro.StaticValue(n)
+	}
+	if sv.Op() == ir.OLITERAL {
+		return sv.Val()
+	}
+	return nil
+}
+
+// isNil returns whether n is nil (or singly
+// assigned local containing nil).
+func (nf *nameFinder) isNil(n ir.Node) bool {
+	sv := n
+	if nf.ro != nil {
+		sv = nf.ro.StaticValue(n)
+	}
+	return sv.Op() == ir.ONIL
+}
+
+func (nf *nameFinder) staticValue(n ir.Node) ir.Node {
+	if nf.ro == nil {
+		return n
+	}
+	return nf.ro.StaticValue(n)
+}
+
+func (nf *nameFinder) reassigned(n *ir.Name) bool {
+	if nf.ro == nil {
+		return true
+	}
+	return nf.ro.Reassigned(n)
+}
+
+func (nf *nameFinder) isConcreteConvIface(n ir.Node) bool {
+	sv := n
+	if nf.ro != nil {
+		sv = nf.ro.StaticValue(n)
+	}
+	if sv.Op() != ir.OCONVIFACE {
+		return false
+	}
+	return !sv.(*ir.ConvExpr).X.Type().IsInterface()
+}
+
+func isSameFuncName(v1, v2 *ir.Name) bool {
+	// NB: there are a few corner cases where pointer equality
+	// doesn't work here, but this should be good enough for
+	// our purposes here.
+	return v1 == v2
+}

src/cmd/compile/internal/inline/inlheur/parampropbits_string.go

@@ -0,0 +1,70 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Code generated by "stringer -bitset -type ParamPropBits"; DO NOT EDIT.
+
+package inlheur
+
+import (
+	"bytes"
+	"strconv"
+)
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[ParamNoInfo-0]
+	_ = x[ParamFeedsInterfaceMethodCall-2]
+	_ = x[ParamMayFeedInterfaceMethodCall-4]
+	_ = x[ParamFeedsIndirectCall-8]
+	_ = x[ParamMayFeedIndirectCall-16]
+	_ = x[ParamFeedsIfOrSwitch-32]
+	_ = x[ParamMayFeedIfOrSwitch-64]
+}
+
+var _ParamPropBits_value = [...]uint64{
+	0x0,  /* ParamNoInfo */
+	0x2,  /* ParamFeedsInterfaceMethodCall */
+	0x4,  /* ParamMayFeedInterfaceMethodCall */
+	0x8,  /* ParamFeedsIndirectCall */
+	0x10, /* ParamMayFeedIndirectCall */
+	0x20, /* ParamFeedsIfOrSwitch */
+	0x40, /* ParamMayFeedIfOrSwitch */
+}
+
+const _ParamPropBits_name = "ParamNoInfoParamFeedsInterfaceMethodCallParamMayFeedInterfaceMethodCallParamFeedsIndirectCallParamMayFeedIndirectCallParamFeedsIfOrSwitchParamMayFeedIfOrSwitch"
+
+var _ParamPropBits_index = [...]uint8{0, 11, 40, 71, 93, 117, 137, 159}
+
+func (i ParamPropBits) String() string {
+	var b bytes.Buffer
+
+	remain := uint64(i)
+	seen := false
+
+	for k, v := range _ParamPropBits_value {
+		x := _ParamPropBits_name[_ParamPropBits_index[k]:_ParamPropBits_index[k+1]]
+		if v == 0 {
+			if i == 0 {
+				b.WriteString(x)
+				return b.String()
+			}
+			continue
+		}
+		if (v & remain) == v {
+			remain &^= v
+			x := _ParamPropBits_name[_ParamPropBits_index[k]:_ParamPropBits_index[k+1]]
+			if seen {
+				b.WriteString("|")
+			}
+			seen = true
+			b.WriteString(x)
+		}
+	}
+	if remain == 0 {
+		return b.String()
+	}
+	return "ParamPropBits(0x" + strconv.FormatInt(int64(i), 16) + ")"
+}

src/cmd/compile/internal/inline/inlheur/pstate_string.go

@@ -0,0 +1,30 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Code generated by "stringer -type pstate"; DO NOT EDIT.
+
+package inlheur
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[psNoInfo-0]
+	_ = x[psCallsPanic-1]
+	_ = x[psMayReturn-2]
+	_ = x[psTop-3]
+}
+
+const _pstate_name = "psNoInfopsCallsPanicpsMayReturnpsTop"
+
+var _pstate_index = [...]uint8{0, 8, 20, 31, 36}
+
+func (i pstate) String() string {
+	if i < 0 || i >= pstate(len(_pstate_index)-1) {
+		return "pstate(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _pstate_name[_pstate_index[i]:_pstate_index[i+1]]
+}

src/cmd/compile/internal/inline/inlheur/resultpropbits_string.go

@@ -0,0 +1,68 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Code generated by "stringer -bitset -type ResultPropBits"; DO NOT EDIT.
+
+package inlheur
+
+import (
+	"bytes"
+	"strconv"
+)
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[ResultNoInfo-0]
+	_ = x[ResultIsAllocatedMem-2]
+	_ = x[ResultIsConcreteTypeConvertedToInterface-4]
+	_ = x[ResultAlwaysSameConstant-8]
+	_ = x[ResultAlwaysSameFunc-16]
+	_ = x[ResultAlwaysSameInlinableFunc-32]
+}
+
+var _ResultPropBits_value = [...]uint64{
+	0x0,  /* ResultNoInfo */
+	0x2,  /* ResultIsAllocatedMem */
+	0x4,  /* ResultIsConcreteTypeConvertedToInterface */
+	0x8,  /* ResultAlwaysSameConstant */
+	0x10, /* ResultAlwaysSameFunc */
+	0x20, /* ResultAlwaysSameInlinableFunc */
+}
+
+const _ResultPropBits_name = "ResultNoInfoResultIsAllocatedMemResultIsConcreteTypeConvertedToInterfaceResultAlwaysSameConstantResultAlwaysSameFuncResultAlwaysSameInlinableFunc"
+
+var _ResultPropBits_index = [...]uint8{0, 12, 32, 72, 96, 116, 145}
+
+func (i ResultPropBits) String() string {
+	var b bytes.Buffer
+
+	remain := uint64(i)
+	seen := false
+
+	for k, v := range _ResultPropBits_value {
+		x := _ResultPropBits_name[_ResultPropBits_index[k]:_ResultPropBits_index[k+1]]
+		if v == 0 {
+			if i == 0 {
+				b.WriteString(x)
+				return b.String()
+			}
+			continue
+		}
+		if (v & remain) == v {
+			remain &^= v
+			x := _ResultPropBits_name[_ResultPropBits_index[k]:_ResultPropBits_index[k+1]]
+			if seen {
+				b.WriteString("|")
+			}
+			seen = true
+			b.WriteString(x)
+		}
+	}
+	if remain == 0 {
+		return b.String()
+	}
+	return "ResultPropBits(0x" + strconv.FormatInt(int64(i), 16) + ")"
+}

src/cmd/compile/internal/inline/inlheur/score_callresult_uses.go

@@ -0,0 +1,413 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"cmd/compile/internal/ir"
+	"fmt"
+	"os"
+)
+
+// This file contains code to re-score callsites based on how the
+// results of the call were used.  Example:
+//
+//    func foo() {
+//       x, fptr := bar()
+//       switch x {
+//         case 10: fptr = baz()
+//         default: blix()
+//       }
+//       fptr(100)
+//     }
+//
+// The initial scoring pass will assign a score to "bar()" based on
+// various criteria, however once the first pass of scoring is done,
+// we look at the flags on the result from bar, and check to see
+// how those results are used. If bar() always returns the same constant
+// for its first result, and if the variable receiving that result
+// isn't redefined, and if that variable feeds into an if/switch
+// condition, then we will try to adjust the score for "bar" (on the
+// theory that if we inlined, we can constant fold / deadcode).
+
+type resultPropAndCS struct {
+	defcs *CallSite
+	props ResultPropBits
+}
+
+type resultUseAnalyzer struct {
+	resultNameTab map[*ir.Name]resultPropAndCS
+	fn            *ir.Func
+	cstab         CallSiteTab
+	*condLevelTracker
+}
+
+// rescoreBasedOnCallResultUses examines how call results are used,
+// and tries to update the scores of calls based on how their results
+// are used in the function.
+func (csa *callSiteAnalyzer) rescoreBasedOnCallResultUses(fn *ir.Func, resultNameTab map[*ir.Name]resultPropAndCS, cstab CallSiteTab) {
+	enableDebugTraceIfEnv()
+	rua := &resultUseAnalyzer{
+		resultNameTab:    resultNameTab,
+		fn:               fn,
+		cstab:            cstab,
+		condLevelTracker: new(condLevelTracker),
+	}
+	var doNode func(ir.Node) bool
+	doNode = func(n ir.Node) bool {
+		rua.nodeVisitPre(n)
+		ir.DoChildren(n, doNode)
+		rua.nodeVisitPost(n)
+		return false
+	}
+	doNode(fn)
+	disableDebugTrace()
+}
+
+func (csa *callSiteAnalyzer) examineCallResults(cs *CallSite, resultNameTab map[*ir.Name]resultPropAndCS) map[*ir.Name]resultPropAndCS {
+	if debugTrace&debugTraceScoring != 0 {
+		fmt.Fprintf(os.Stderr, "=-= examining call results for %q\n",
+			EncodeCallSiteKey(cs))
+	}
+
+	// Invoke a helper to pick out the specific ir.Name's the results
+	// from this call are assigned into, e.g. "x, y := fooBar()". If
+	// the call is not part of an assignment statement, or if the
+	// variables in question are not newly defined, then we'll receive
+	// an empty list here.
+	//
+	names, autoTemps, props := namesDefined(cs)
+	if len(names) == 0 {
+		return resultNameTab
+	}
+
+	if debugTrace&debugTraceScoring != 0 {
+		fmt.Fprintf(os.Stderr, "=-= %d names defined\n", len(names))
+	}
+
+	// For each returned value, if the value has interesting
+	// properties (ex: always returns the same constant), and the name
+	// in question is never redefined, then make an entry in the
+	// result table for it.
+	const interesting = (ResultIsConcreteTypeConvertedToInterface |
+		ResultAlwaysSameConstant | ResultAlwaysSameInlinableFunc | ResultAlwaysSameFunc)
+	for idx, n := range names {
+		rprop := props.ResultFlags[idx]
+
+		if debugTrace&debugTraceScoring != 0 {
+			fmt.Fprintf(os.Stderr, "=-= props for ret %d %q: %s\n",
+				idx, n.Sym().Name, rprop.String())
+		}
+
+		if rprop&interesting == 0 {
+			continue
+		}
+		if csa.nameFinder.reassigned(n) {
+			continue
+		}
+		if resultNameTab == nil {
+			resultNameTab = make(map[*ir.Name]resultPropAndCS)
+		} else if _, ok := resultNameTab[n]; ok {
+			panic("should never happen")
+		}
+		entry := resultPropAndCS{
+			defcs: cs,
+			props: rprop,
+		}
+		resultNameTab[n] = entry
+		if autoTemps[idx] != nil {
+			resultNameTab[autoTemps[idx]] = entry
+		}
+		if debugTrace&debugTraceScoring != 0 {
+			fmt.Fprintf(os.Stderr, "=-= add resultNameTab table entry n=%v autotemp=%v props=%s\n", n, autoTemps[idx], rprop.String())
+		}
+	}
+	return resultNameTab
+}
+
+// namesDefined returns a list of ir.Name's corresponding to locals
+// that receive the results from the call at site 'cs', plus the
+// properties object for the called function. If a given result
+// isn't cleanly assigned to a newly defined local, the
+// slot for that result in the returned list will be nil. Example:
+//
+//	call                             returned name list
+//
+//	x := foo()                       [ x ]
+//	z, y := bar()                    [ nil, nil ]
+//	_, q := baz()                    [ nil, q ]
+//
+// In the case of a multi-return call, such as "x, y := foo()",
+// the pattern we see from the front end will be a call op
+// assigning to auto-temps, and then an assignment of the auto-temps
+// to the user-level variables. In such cases we return
+// first the user-level variable (in the first func result)
+// and then the auto-temp name in the second result.
+func namesDefined(cs *CallSite) ([]*ir.Name, []*ir.Name, *FuncProps) {
+	// If this call doesn't feed into an assignment (and of course not
+	// all calls do), then we don't have anything to work with here.
+	if cs.Assign == nil {
+		return nil, nil, nil
+	}
+	funcInlHeur, ok := fpmap[cs.Callee]
+	if !ok {
+		// TODO: add an assert/panic here.
+		return nil, nil, nil
+	}
+	if len(funcInlHeur.props.ResultFlags) == 0 {
+		return nil, nil, nil
+	}
+
+	// Single return case.
+	if len(funcInlHeur.props.ResultFlags) == 1 {
+		asgn, ok := cs.Assign.(*ir.AssignStmt)
+		if !ok {
+			return nil, nil, nil
+		}
+		// locate name being assigned
+		aname, ok := asgn.X.(*ir.Name)
+		if !ok {
+			return nil, nil, nil
+		}
+		return []*ir.Name{aname}, []*ir.Name{nil}, funcInlHeur.props
+	}
+
+	// Multi-return case
+	asgn, ok := cs.Assign.(*ir.AssignListStmt)
+	if !ok || !asgn.Def {
+		return nil, nil, nil
+	}
+	userVars := make([]*ir.Name, len(funcInlHeur.props.ResultFlags))
+	autoTemps := make([]*ir.Name, len(funcInlHeur.props.ResultFlags))
+	for idx, x := range asgn.Lhs {
+		if n, ok := x.(*ir.Name); ok {
+			userVars[idx] = n
+			r := asgn.Rhs[idx]
+			if r.Op() == ir.OCONVNOP {
+				r = r.(*ir.ConvExpr).X
+			}
+			if ir.IsAutoTmp(r) {
+				autoTemps[idx] = r.(*ir.Name)
+			}
+			if debugTrace&debugTraceScoring != 0 {
+				fmt.Fprintf(os.Stderr, "=-= multi-ret namedef uv=%v at=%v\n",
+					x, autoTemps[idx])
+			}
+		} else {
+			return nil, nil, nil
+		}
+	}
+	return userVars, autoTemps, funcInlHeur.props
+}
+
+func (rua *resultUseAnalyzer) nodeVisitPost(n ir.Node) {
+	rua.condLevelTracker.post(n)
+}
+
+func (rua *resultUseAnalyzer) nodeVisitPre(n ir.Node) {
+	rua.condLevelTracker.pre(n)
+	switch n.Op() {
+	case ir.OCALLINTER:
+		if debugTrace&debugTraceScoring != 0 {
+			fmt.Fprintf(os.Stderr, "=-= rescore examine iface call %v:\n", n)
+		}
+		rua.callTargetCheckResults(n)
+	case ir.OCALLFUNC:
+		if debugTrace&debugTraceScoring != 0 {
+			fmt.Fprintf(os.Stderr, "=-= rescore examine call %v:\n", n)
+		}
+		rua.callTargetCheckResults(n)
+	case ir.OIF:
+		ifst := n.(*ir.IfStmt)
+		rua.foldCheckResults(ifst.Cond)
+	case ir.OSWITCH:
+		swst := n.(*ir.SwitchStmt)
+		if swst.Tag != nil {
+			rua.foldCheckResults(swst.Tag)
+		}
+
+	}
+}
+
+// callTargetCheckResults examines a given call to see whether the
+// callee expression is potentially an inlinable function returned
+// from a potentially inlinable call. Examples:
+//
+//	Scenario 1: named intermediate
+//
+//	   fn1 := foo()         conc := bar()
+//	   fn1("blah")          conc.MyMethod()
+//
+//	Scenario 2: returned func or concrete object feeds directly to call
+//
+//	   foo()("blah")        bar().MyMethod()
+//
+// In the second case although at the source level the result of the
+// direct call feeds right into the method call or indirect call,
+// we're relying on the front end having inserted an auto-temp to
+// capture the value.
+func (rua *resultUseAnalyzer) callTargetCheckResults(call ir.Node) {
+	ce := call.(*ir.CallExpr)
+	rname := rua.getCallResultName(ce)
+	if rname == nil {
+		return
+	}
+	if debugTrace&debugTraceScoring != 0 {
+		fmt.Fprintf(os.Stderr, "=-= staticvalue returns %v:\n",
+			rname)
+	}
+	if rname.Class != ir.PAUTO {
+		return
+	}
+	switch call.Op() {
+	case ir.OCALLINTER:
+		if debugTrace&debugTraceScoring != 0 {
+			fmt.Fprintf(os.Stderr, "=-= in %s checking %v for cci prop:\n",
+				rua.fn.Sym().Name, rname)
+		}
+		if cs := rua.returnHasProp(rname, ResultIsConcreteTypeConvertedToInterface); cs != nil {
+
+			adj := returnFeedsConcreteToInterfaceCallAdj
+			cs.Score, cs.ScoreMask = adjustScore(adj, cs.Score, cs.ScoreMask)
+		}
+	case ir.OCALLFUNC:
+		if debugTrace&debugTraceScoring != 0 {
+			fmt.Fprintf(os.Stderr, "=-= in %s checking %v for samefunc props:\n",
+				rua.fn.Sym().Name, rname)
+			v, ok := rua.resultNameTab[rname]
+			if !ok {
+				fmt.Fprintf(os.Stderr, "=-= no entry for %v in rt\n", rname)
+			} else {
+				fmt.Fprintf(os.Stderr, "=-= props for %v: %q\n", rname, v.props.String())
+			}
+		}
+		if cs := rua.returnHasProp(rname, ResultAlwaysSameInlinableFunc); cs != nil {
+			adj := returnFeedsInlinableFuncToIndCallAdj
+			cs.Score, cs.ScoreMask = adjustScore(adj, cs.Score, cs.ScoreMask)
+		} else if cs := rua.returnHasProp(rname, ResultAlwaysSameFunc); cs != nil {
+			adj := returnFeedsFuncToIndCallAdj
+			cs.Score, cs.ScoreMask = adjustScore(adj, cs.Score, cs.ScoreMask)
+
+		}
+	}
+}
+
+// foldCheckResults examines the specified if/switch condition 'cond'
+// to see if it refers to locals defined by a (potentially inlinable)
+// function call at call site C, and if so, whether 'cond' contains
+// only combinations of simple references to all of the names in
+// 'names' with selected constants + operators. If these criteria are
+// met, then we adjust the score for call site C to reflect the
+// fact that inlining will enable deadcode and/or constant propagation.
+// Note: for this heuristic to kick in, the names in question have to
+// be all from the same callsite. Examples:
+//
+//	  q, r := baz()	    x, y := foo()
+//	  switch q+r {		a, b, c := bar()
+//		...			    if x && y && a && b && c {
+//	  }					   ...
+//					    }
+//
+// For the call to "baz" above we apply a score adjustment, but not
+// for the calls to "foo" or "bar".
+func (rua *resultUseAnalyzer) foldCheckResults(cond ir.Node) {
+	namesUsed := collectNamesUsed(cond)
+	if len(namesUsed) == 0 {
+		return
+	}
+	var cs *CallSite
+	for _, n := range namesUsed {
+		rpcs, found := rua.resultNameTab[n]
+		if !found {
+			return
+		}
+		if cs != nil && rpcs.defcs != cs {
+			return
+		}
+		cs = rpcs.defcs
+		if rpcs.props&ResultAlwaysSameConstant == 0 {
+			return
+		}
+	}
+	if debugTrace&debugTraceScoring != 0 {
+		nls := func(nl []*ir.Name) string {
+			r := ""
+			for _, n := range nl {
+				r += " " + n.Sym().Name
+			}
+			return r
+		}
+		fmt.Fprintf(os.Stderr, "=-= calling ShouldFoldIfNameConstant on names={%s} cond=%v\n", nls(namesUsed), cond)
+	}
+
+	if !ShouldFoldIfNameConstant(cond, namesUsed) {
+		return
+	}
+	adj := returnFeedsConstToIfAdj
+	cs.Score, cs.ScoreMask = adjustScore(adj, cs.Score, cs.ScoreMask)
+}
+
+func collectNamesUsed(expr ir.Node) []*ir.Name {
+	res := []*ir.Name{}
+	ir.Visit(expr, func(n ir.Node) {
+		if n.Op() != ir.ONAME {
+			return
+		}
+		nn := n.(*ir.Name)
+		if nn.Class != ir.PAUTO {
+			return
+		}
+		res = append(res, nn)
+	})
+	return res
+}
+
+func (rua *resultUseAnalyzer) returnHasProp(name *ir.Name, prop ResultPropBits) *CallSite {
+	v, ok := rua.resultNameTab[name]
+	if !ok {
+		return nil
+	}
+	if v.props&prop == 0 {
+		return nil
+	}
+	return v.defcs
+}
+
+func (rua *resultUseAnalyzer) getCallResultName(ce *ir.CallExpr) *ir.Name {
+	var callTarg ir.Node
+	if sel, ok := ce.Fun.(*ir.SelectorExpr); ok {
+		// method call
+		callTarg = sel.X
+	} else if ctarg, ok := ce.Fun.(*ir.Name); ok {
+		// regular call
+		callTarg = ctarg
+	} else {
+		return nil
+	}
+	r := ir.StaticValue(callTarg)
+	if debugTrace&debugTraceScoring != 0 {
+		fmt.Fprintf(os.Stderr, "=-= staticname on %v returns %v:\n",
+			callTarg, r)
+	}
+	if r.Op() == ir.OCALLFUNC {
+		// This corresponds to the "x := foo()" case; here
+		// ir.StaticValue has brought us all the way back to
+		// the call expression itself. We need to back off to
+		// the name defined by the call; do this by looking up
+		// the callsite.
+		ce := r.(*ir.CallExpr)
+		cs, ok := rua.cstab[ce]
+		if !ok {
+			return nil
+		}
+		names, _, _ := namesDefined(cs)
+		if len(names) == 0 {
+			return nil
+		}
+		return names[0]
+	} else if r.Op() == ir.ONAME {
+		return r.(*ir.Name)
+	}
+	return nil
+}

src/cmd/compile/internal/inline/inlheur/scoreadjusttyp_string.go

@@ -0,0 +1,80 @@
+// Code generated by "stringer -bitset -type scoreAdjustTyp"; DO NOT EDIT.
+
+package inlheur
+
+import "strconv"
+import "bytes"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[panicPathAdj-1]
+	_ = x[initFuncAdj-2]
+	_ = x[inLoopAdj-4]
+	_ = x[passConstToIfAdj-8]
+	_ = x[passConstToNestedIfAdj-16]
+	_ = x[passConcreteToItfCallAdj-32]
+	_ = x[passConcreteToNestedItfCallAdj-64]
+	_ = x[passFuncToIndCallAdj-128]
+	_ = x[passFuncToNestedIndCallAdj-256]
+	_ = x[passInlinableFuncToIndCallAdj-512]
+	_ = x[passInlinableFuncToNestedIndCallAdj-1024]
+	_ = x[returnFeedsConstToIfAdj-2048]
+	_ = x[returnFeedsFuncToIndCallAdj-4096]
+	_ = x[returnFeedsInlinableFuncToIndCallAdj-8192]
+	_ = x[returnFeedsConcreteToInterfaceCallAdj-16384]
+}
+
+var _scoreAdjustTyp_value = [...]uint64{
+	0x1,    /* panicPathAdj */
+	0x2,    /* initFuncAdj */
+	0x4,    /* inLoopAdj */
+	0x8,    /* passConstToIfAdj */
+	0x10,   /* passConstToNestedIfAdj */
+	0x20,   /* passConcreteToItfCallAdj */
+	0x40,   /* passConcreteToNestedItfCallAdj */
+	0x80,   /* passFuncToIndCallAdj */
+	0x100,  /* passFuncToNestedIndCallAdj */
+	0x200,  /* passInlinableFuncToIndCallAdj */
+	0x400,  /* passInlinableFuncToNestedIndCallAdj */
+	0x800,  /* returnFeedsConstToIfAdj */
+	0x1000, /* returnFeedsFuncToIndCallAdj */
+	0x2000, /* returnFeedsInlinableFuncToIndCallAdj */
+	0x4000, /* returnFeedsConcreteToInterfaceCallAdj */
+}
+
+const _scoreAdjustTyp_name = "panicPathAdjinitFuncAdjinLoopAdjpassConstToIfAdjpassConstToNestedIfAdjpassConcreteToItfCallAdjpassConcreteToNestedItfCallAdjpassFuncToIndCallAdjpassFuncToNestedIndCallAdjpassInlinableFuncToIndCallAdjpassInlinableFuncToNestedIndCallAdjreturnFeedsConstToIfAdjreturnFeedsFuncToIndCallAdjreturnFeedsInlinableFuncToIndCallAdjreturnFeedsConcreteToInterfaceCallAdj"
+
+var _scoreAdjustTyp_index = [...]uint16{0, 12, 23, 32, 48, 70, 94, 124, 144, 170, 199, 234, 257, 284, 320, 357}
+
+func (i scoreAdjustTyp) String() string {
+	var b bytes.Buffer
+
+	remain := uint64(i)
+	seen := false
+
+	for k, v := range _scoreAdjustTyp_value {
+		x := _scoreAdjustTyp_name[_scoreAdjustTyp_index[k]:_scoreAdjustTyp_index[k+1]]
+		if v == 0 {
+			if i == 0 {
+				b.WriteString(x)
+				return b.String()
+			}
+			continue
+		}
+		if (v & remain) == v {
+			remain &^= v
+			x := _scoreAdjustTyp_name[_scoreAdjustTyp_index[k]:_scoreAdjustTyp_index[k+1]]
+			if seen {
+				b.WriteString("|")
+			}
+			seen = true
+			b.WriteString(x)
+		}
+	}
+	if remain == 0 {
+		return b.String()
+	}
+	return "scoreAdjustTyp(0x" + strconv.FormatInt(int64(i), 16) + ")"
+}

src/cmd/compile/internal/inline/inlheur/scoring.go

@@ -0,0 +1,751 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/pgoir"
+	"cmd/compile/internal/types"
+	"fmt"
+	"os"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+// These constants enumerate the set of possible ways/scenarios
+// in which we'll adjust the score of a given callsite.
+type scoreAdjustTyp uint
+
+// These constants capture the various ways in which the inliner's
+// scoring phase can adjust a callsite score based on heuristics. They
+// fall broadly into three categories:
+//
+// 1) adjustments based solely on the callsite context (ex: call
+// appears on panic path)
+//
+// 2) adjustments that take into account specific interesting values
+// passed at a call site (ex: passing a constant that could result in
+// cprop/deadcode in the caller)
+//
+// 3) adjustments that take into account values returned from the call
+// at a callsite (ex: call always returns the same inlinable function,
+// and return value flows unmodified into an indirect call)
+//
+// For categories 2 and 3 above, each adjustment can have either a
+// "must" version and a "may" version (but not both). Here the idea is
+// that in the "must" version the value flow is unconditional: if the
+// callsite executes, then the condition we're interested in (ex:
+// param feeding call) is guaranteed to happen. For the "may" version,
+// there may be control flow that could cause the benefit to be
+// bypassed.
+const (
+	// Category 1 adjustments (see above)
+	panicPathAdj scoreAdjustTyp = (1 << iota)
+	initFuncAdj
+	inLoopAdj
+
+	// Category 2 adjustments (see above).
+	passConstToIfAdj
+	passConstToNestedIfAdj
+	passConcreteToItfCallAdj
+	passConcreteToNestedItfCallAdj
+	passFuncToIndCallAdj
+	passFuncToNestedIndCallAdj
+	passInlinableFuncToIndCallAdj
+	passInlinableFuncToNestedIndCallAdj
+
+	// Category 3 adjustments.
+	returnFeedsConstToIfAdj
+	returnFeedsFuncToIndCallAdj
+	returnFeedsInlinableFuncToIndCallAdj
+	returnFeedsConcreteToInterfaceCallAdj
+
+	sentinelScoreAdj // sentinel; not a real adjustment
+)
+
+// This table records the specific values we use to adjust call
+// site scores in a given scenario.
+// NOTE: these numbers are chosen very arbitrarily; ideally
+// we will go through some sort of turning process to decide
+// what value for each one produces the best performance.
+
+var adjValues = map[scoreAdjustTyp]int{
+	panicPathAdj:                          40,
+	initFuncAdj:                           20,
+	inLoopAdj:                             -5,
+	passConstToIfAdj:                      -20,
+	passConstToNestedIfAdj:                -15,
+	passConcreteToItfCallAdj:              -30,
+	passConcreteToNestedItfCallAdj:        -25,
+	passFuncToIndCallAdj:                  -25,
+	passFuncToNestedIndCallAdj:            -20,
+	passInlinableFuncToIndCallAdj:         -45,
+	passInlinableFuncToNestedIndCallAdj:   -40,
+	returnFeedsConstToIfAdj:               -15,
+	returnFeedsFuncToIndCallAdj:           -25,
+	returnFeedsInlinableFuncToIndCallAdj:  -40,
+	returnFeedsConcreteToInterfaceCallAdj: -25,
+}
+
+// SetupScoreAdjustments interprets the value of the -d=inlscoreadj
+// debugging option, if set. The value of this flag is expected to be
+// a series of "/"-separated clauses of the form adj1:value1. Example:
+// -d=inlscoreadj=inLoopAdj=0/passConstToIfAdj=-99
+func SetupScoreAdjustments() {
+	if base.Debug.InlScoreAdj == "" {
+		return
+	}
+	if err := parseScoreAdj(base.Debug.InlScoreAdj); err != nil {
+		base.Fatalf("malformed -d=inlscoreadj argument %q: %v",
+			base.Debug.InlScoreAdj, err)
+	}
+}
+
+func adjStringToVal(s string) (scoreAdjustTyp, bool) {
+	for adj := scoreAdjustTyp(1); adj < sentinelScoreAdj; adj <<= 1 {
+		if adj.String() == s {
+			return adj, true
+		}
+	}
+	return 0, false
+}
+
+func parseScoreAdj(val string) error {
+	clauses := strings.Split(val, "/")
+	if len(clauses) == 0 {
+		return fmt.Errorf("no clauses")
+	}
+	for _, clause := range clauses {
+		elems := strings.Split(clause, ":")
+		if len(elems) < 2 {
+			return fmt.Errorf("clause %q: expected colon", clause)
+		}
+		if len(elems) != 2 {
+			return fmt.Errorf("clause %q has %d elements, wanted 2", clause,
+				len(elems))
+		}
+		adj, ok := adjStringToVal(elems[0])
+		if !ok {
+			return fmt.Errorf("clause %q: unknown adjustment", clause)
+		}
+		val, err := strconv.Atoi(elems[1])
+		if err != nil {
+			return fmt.Errorf("clause %q: malformed value: %v", clause, err)
+		}
+		adjValues[adj] = val
+	}
+	return nil
+}
+
+func adjValue(x scoreAdjustTyp) int {
+	if val, ok := adjValues[x]; ok {
+		return val
+	} else {
+		panic("internal error unregistered adjustment type")
+	}
+}
+
+var mayMustAdj = [...]struct{ may, must scoreAdjustTyp }{
+	{may: passConstToNestedIfAdj, must: passConstToIfAdj},
+	{may: passConcreteToNestedItfCallAdj, must: passConcreteToItfCallAdj},
+	{may: passFuncToNestedIndCallAdj, must: passFuncToNestedIndCallAdj},
+	{may: passInlinableFuncToNestedIndCallAdj, must: passInlinableFuncToIndCallAdj},
+}
+
+func isMay(x scoreAdjustTyp) bool {
+	return mayToMust(x) != 0
+}
+
+func isMust(x scoreAdjustTyp) bool {
+	return mustToMay(x) != 0
+}
+
+func mayToMust(x scoreAdjustTyp) scoreAdjustTyp {
+	for _, v := range mayMustAdj {
+		if x == v.may {
+			return v.must
+		}
+	}
+	return 0
+}
+
+func mustToMay(x scoreAdjustTyp) scoreAdjustTyp {
+	for _, v := range mayMustAdj {
+		if x == v.must {
+			return v.may
+		}
+	}
+	return 0
+}
+
+// computeCallSiteScore takes a given call site whose ir node is
+// 'call' and callee function is 'callee' and with previously computed
+// call site properties 'csflags', then computes a score for the
+// callsite that combines the size cost of the callee with heuristics
+// based on previously computed argument and function properties,
+// then stores the score and the adjustment mask in the appropriate
+// fields in 'cs'
+func (cs *CallSite) computeCallSiteScore(csa *callSiteAnalyzer, calleeProps *FuncProps) {
+	callee := cs.Callee
+	csflags := cs.Flags
+	call := cs.Call
+
+	// Start with the size-based score for the callee.
+	score := int(callee.Inl.Cost)
+	var tmask scoreAdjustTyp
+
+	if debugTrace&debugTraceScoring != 0 {
+		fmt.Fprintf(os.Stderr, "=-= scoring call to %s at %s , initial=%d\n",
+			callee.Sym().Name, fmtFullPos(call.Pos()), score)
+	}
+
+	// First some score adjustments to discourage inlining in selected cases.
+	if csflags&CallSiteOnPanicPath != 0 {
+		score, tmask = adjustScore(panicPathAdj, score, tmask)
+	}
+	if csflags&CallSiteInInitFunc != 0 {
+		score, tmask = adjustScore(initFuncAdj, score, tmask)
+	}
+
+	// Then adjustments to encourage inlining in selected cases.
+	if csflags&CallSiteInLoop != 0 {
+		score, tmask = adjustScore(inLoopAdj, score, tmask)
+	}
+
+	// Stop here if no callee props.
+	if calleeProps == nil {
+		cs.Score, cs.ScoreMask = score, tmask
+		return
+	}
+
+	// Walk through the actual expressions being passed at the call.
+	calleeRecvrParms := callee.Type().RecvParams()
+	for idx := range call.Args {
+		// ignore blanks
+		if calleeRecvrParms[idx].Sym == nil ||
+			calleeRecvrParms[idx].Sym.IsBlank() {
+			continue
+		}
+		arg := call.Args[idx]
+		pflag := calleeProps.ParamFlags[idx]
+		if debugTrace&debugTraceScoring != 0 {
+			fmt.Fprintf(os.Stderr, "=-= arg %d of %d: val %v flags=%s\n",
+				idx, len(call.Args), arg, pflag.String())
+		}
+
+		if len(cs.ArgProps) == 0 {
+			continue
+		}
+		argProps := cs.ArgProps[idx]
+
+		if debugTrace&debugTraceScoring != 0 {
+			fmt.Fprintf(os.Stderr, "=-= arg %d props %s value %v\n",
+				idx, argProps.String(), arg)
+		}
+
+		if argProps&ActualExprConstant != 0 {
+			if pflag&ParamMayFeedIfOrSwitch != 0 {
+				score, tmask = adjustScore(passConstToNestedIfAdj, score, tmask)
+			}
+			if pflag&ParamFeedsIfOrSwitch != 0 {
+				score, tmask = adjustScore(passConstToIfAdj, score, tmask)
+			}
+		}
+
+		if argProps&ActualExprIsConcreteConvIface != 0 {
+			// FIXME: ideally here it would be nice to make a
+			// distinction between the inlinable case and the
+			// non-inlinable case, but this is hard to do. Example:
+			//
+			//    type I interface { Tiny() int; Giant() }
+			//    type Conc struct { x int }
+			//    func (c *Conc) Tiny() int { return 42 }
+			//    func (c *Conc) Giant() { <huge amounts of code> }
+			//
+			//    func passConcToItf(c *Conc) {
+			//        makesItfMethodCall(c)
+			//    }
+			//
+			// In the code above, function properties will only tell
+			// us that 'makesItfMethodCall' invokes a method on its
+			// interface parameter, but we don't know whether it calls
+			// "Tiny" or "Giant". If we knew if called "Tiny", then in
+			// theory in addition to converting the interface call to
+			// a direct call, we could also inline (in which case
+			// we'd want to decrease the score even more).
+			//
+			// One thing we could do (not yet implemented) is iterate
+			// through all of the methods of "*Conc" that allow it to
+			// satisfy I, and if all are inlinable, then exploit that.
+			if pflag&ParamMayFeedInterfaceMethodCall != 0 {
+				score, tmask = adjustScore(passConcreteToNestedItfCallAdj, score, tmask)
+			}
+			if pflag&ParamFeedsInterfaceMethodCall != 0 {
+				score, tmask = adjustScore(passConcreteToItfCallAdj, score, tmask)
+			}
+		}
+
+		if argProps&(ActualExprIsFunc|ActualExprIsInlinableFunc) != 0 {
+			mayadj := passFuncToNestedIndCallAdj
+			mustadj := passFuncToIndCallAdj
+			if argProps&ActualExprIsInlinableFunc != 0 {
+				mayadj = passInlinableFuncToNestedIndCallAdj
+				mustadj = passInlinableFuncToIndCallAdj
+			}
+			if pflag&ParamMayFeedIndirectCall != 0 {
+				score, tmask = adjustScore(mayadj, score, tmask)
+			}
+			if pflag&ParamFeedsIndirectCall != 0 {
+				score, tmask = adjustScore(mustadj, score, tmask)
+			}
+		}
+	}
+
+	cs.Score, cs.ScoreMask = score, tmask
+}
+
+func adjustScore(typ scoreAdjustTyp, score int, mask scoreAdjustTyp) (int, scoreAdjustTyp) {
+
+	if isMust(typ) {
+		if mask&typ != 0 {
+			return score, mask
+		}
+		may := mustToMay(typ)
+		if mask&may != 0 {
+			// promote may to must, so undo may
+			score -= adjValue(may)
+			mask &^= may
+		}
+	} else if isMay(typ) {
+		must := mayToMust(typ)
+		if mask&(must|typ) != 0 {
+			return score, mask
+		}
+	}
+	if mask&typ == 0 {
+		if debugTrace&debugTraceScoring != 0 {
+			fmt.Fprintf(os.Stderr, "=-= applying adj %d for %s\n",
+				adjValue(typ), typ.String())
+		}
+		score += adjValue(typ)
+		mask |= typ
+	}
+	return score, mask
+}
+
+var resultFlagToPositiveAdj map[ResultPropBits]scoreAdjustTyp
+var paramFlagToPositiveAdj map[ParamPropBits]scoreAdjustTyp
+
+func setupFlagToAdjMaps() {
+	resultFlagToPositiveAdj = map[ResultPropBits]scoreAdjustTyp{
+		ResultIsAllocatedMem:     returnFeedsConcreteToInterfaceCallAdj,
+		ResultAlwaysSameFunc:     returnFeedsFuncToIndCallAdj,
+		ResultAlwaysSameConstant: returnFeedsConstToIfAdj,
+	}
+	paramFlagToPositiveAdj = map[ParamPropBits]scoreAdjustTyp{
+		ParamMayFeedInterfaceMethodCall: passConcreteToNestedItfCallAdj,
+		ParamFeedsInterfaceMethodCall:   passConcreteToItfCallAdj,
+		ParamMayFeedIndirectCall:        passInlinableFuncToNestedIndCallAdj,
+		ParamFeedsIndirectCall:          passInlinableFuncToIndCallAdj,
+	}
+}
+
+// LargestNegativeScoreAdjustment tries to estimate the largest possible
+// negative score adjustment that could be applied to a call of the
+// function with the specified props. Example:
+//
+//	func foo() {                  func bar(x int, p *int) int {
+//	   ...                          if x < 0 { *p = x }
+//	}                               return 99
+//	                              }
+//
+// Function 'foo' above on the left has no interesting properties,
+// thus as a result the most we'll adjust any call to is the value for
+// "call in loop". If the calculated cost of the function is 150, and
+// the in-loop adjustment is 5 (for example), then there is not much
+// point treating it as inlinable. On the other hand "bar" has a param
+// property (parameter "x" feeds unmodified to an "if" statement") and
+// a return property (always returns same constant) meaning that a
+// given call _could_ be rescored down as much as -35 points-- thus if
+// the size of "bar" is 100 (for example) then there is at least a
+// chance that scoring will enable inlining.
+func LargestNegativeScoreAdjustment(fn *ir.Func, props *FuncProps) int {
+	if resultFlagToPositiveAdj == nil {
+		setupFlagToAdjMaps()
+	}
+	var tmask scoreAdjustTyp
+	score := adjValues[inLoopAdj] // any call can be in a loop
+	for _, pf := range props.ParamFlags {
+		if adj, ok := paramFlagToPositiveAdj[pf]; ok {
+			score, tmask = adjustScore(adj, score, tmask)
+		}
+	}
+	for _, rf := range props.ResultFlags {
+		if adj, ok := resultFlagToPositiveAdj[rf]; ok {
+			score, tmask = adjustScore(adj, score, tmask)
+		}
+	}
+
+	if debugTrace&debugTraceScoring != 0 {
+		fmt.Fprintf(os.Stderr, "=-= largestScore(%v) is %d\n",
+			fn, score)
+	}
+
+	return score
+}
+
+// LargestPositiveScoreAdjustment tries to estimate the largest possible
+// positive score adjustment that could be applied to a given callsite.
+// At the moment we don't have very many positive score adjustments, so
+// this is just hard-coded, not table-driven.
+func LargestPositiveScoreAdjustment(fn *ir.Func) int {
+	return adjValues[panicPathAdj] + adjValues[initFuncAdj]
+}
+
+// callSiteTab contains entries for each call in the function
+// currently being processed by InlineCalls; this variable will either
+// be set to 'cstabCache' below (for non-inlinable routines) or to the
+// local 'cstab' entry in the fnInlHeur object for inlinable routines.
+//
+// NOTE: this assumes that inlining operations are happening in a serial,
+// single-threaded fashion,f which is true today but probably won't hold
+// in the future (for example, we might want to score the callsites
+// in multiple functions in parallel); if the inliner evolves in this
+// direction we'll need to come up with a different approach here.
+var callSiteTab CallSiteTab
+
+// scoreCallsCache caches a call site table and call site list between
+// invocations of ScoreCalls so that we can reuse previously allocated
+// storage.
+var scoreCallsCache scoreCallsCacheType
+
+type scoreCallsCacheType struct {
+	tab CallSiteTab
+	csl []*CallSite
+}
+
+// ScoreCalls assigns numeric scores to each of the callsites in
+// function 'fn'; the lower the score, the more helpful we think it
+// will be to inline.
+//
+// Unlike a lot of the other inline heuristics machinery, callsite
+// scoring can't be done as part of the CanInline call for a function,
+// due to fact that we may be working on a non-trivial SCC. So for
+// example with this SCC:
+//
+//	func foo(x int) {           func bar(x int, f func()) {
+//	  if x != 0 {                  f()
+//	    bar(x, func(){})           foo(x-1)
+//	  }                         }
+//	}
+//
+// We don't want to perform scoring for the 'foo' call in "bar" until
+// after foo has been analyzed, but it's conceivable that CanInline
+// might visit bar before foo for this SCC.
+func ScoreCalls(fn *ir.Func) {
+	if len(fn.Body) == 0 {
+		return
+	}
+	enableDebugTraceIfEnv()
+
+	nameFinder := newNameFinder(fn)
+
+	if debugTrace&debugTraceScoring != 0 {
+		fmt.Fprintf(os.Stderr, "=-= ScoreCalls(%v)\n", ir.FuncName(fn))
+	}
+
+	// If this is an inlinable function, use the precomputed
+	// call site table for it. If the function wasn't an inline
+	// candidate, collect a callsite table for it now.
+	var cstab CallSiteTab
+	if funcInlHeur, ok := fpmap[fn]; ok {
+		cstab = funcInlHeur.cstab
+	} else {
+		if len(scoreCallsCache.tab) != 0 {
+			panic("missing call to ScoreCallsCleanup")
+		}
+		if scoreCallsCache.tab == nil {
+			scoreCallsCache.tab = make(CallSiteTab)
+		}
+		if debugTrace&debugTraceScoring != 0 {
+			fmt.Fprintf(os.Stderr, "=-= building cstab for non-inl func %s\n",
+				ir.FuncName(fn))
+		}
+		cstab = computeCallSiteTable(fn, fn.Body, scoreCallsCache.tab, nil, 0,
+			nameFinder)
+	}
+
+	csa := makeCallSiteAnalyzer(fn)
+	const doCallResults = true
+	csa.scoreCallsRegion(fn, fn.Body, cstab, doCallResults, nil)
+
+	disableDebugTrace()
+}
+
+// scoreCallsRegion assigns numeric scores to each of the callsites in
+// region 'region' within function 'fn'. This can be called on
+// an entire function, or with 'region' set to a chunk of
+// code corresponding to an inlined call.
+func (csa *callSiteAnalyzer) scoreCallsRegion(fn *ir.Func, region ir.Nodes, cstab CallSiteTab, doCallResults bool, ic *ir.InlinedCallExpr) {
+	if debugTrace&debugTraceScoring != 0 {
+		fmt.Fprintf(os.Stderr, "=-= scoreCallsRegion(%v, %s) len(cstab)=%d\n",
+			ir.FuncName(fn), region[0].Op().String(), len(cstab))
+	}
+
+	// Sort callsites to avoid any surprises with non deterministic
+	// map iteration order (this is probably not needed, but here just
+	// in case).
+	csl := scoreCallsCache.csl[:0]
+	for _, cs := range cstab {
+		csl = append(csl, cs)
+	}
+	scoreCallsCache.csl = csl[:0]
+	sort.Slice(csl, func(i, j int) bool {
+		return csl[i].ID < csl[j].ID
+	})
+
+	// Score each call site.
+	var resultNameTab map[*ir.Name]resultPropAndCS
+	for _, cs := range csl {
+		var cprops *FuncProps
+		fihcprops := false
+		desercprops := false
+		if funcInlHeur, ok := fpmap[cs.Callee]; ok {
+			cprops = funcInlHeur.props
+			fihcprops = true
+		} else if cs.Callee.Inl != nil {
+			cprops = DeserializeFromString(cs.Callee.Inl.Properties)
+			desercprops = true
+		} else {
+			if base.Debug.DumpInlFuncProps != "" {
+				fmt.Fprintf(os.Stderr, "=-= *** unable to score call to %s from %s\n", cs.Callee.Sym().Name, fmtFullPos(cs.Call.Pos()))
+				panic("should never happen")
+			} else {
+				continue
+			}
+		}
+		cs.computeCallSiteScore(csa, cprops)
+
+		if doCallResults {
+			if debugTrace&debugTraceScoring != 0 {
+				fmt.Fprintf(os.Stderr, "=-= examineCallResults at %s: flags=%d score=%d funcInlHeur=%v deser=%v\n", fmtFullPos(cs.Call.Pos()), cs.Flags, cs.Score, fihcprops, desercprops)
+			}
+			resultNameTab = csa.examineCallResults(cs, resultNameTab)
+		}
+
+		if debugTrace&debugTraceScoring != 0 {
+			fmt.Fprintf(os.Stderr, "=-= scoring call at %s: flags=%d score=%d funcInlHeur=%v deser=%v\n", fmtFullPos(cs.Call.Pos()), cs.Flags, cs.Score, fihcprops, desercprops)
+		}
+	}
+
+	if resultNameTab != nil {
+		csa.rescoreBasedOnCallResultUses(fn, resultNameTab, cstab)
+	}
+
+	disableDebugTrace()
+
+	if ic != nil && callSiteTab != nil {
+		// Integrate the calls from this cstab into the table for the caller.
+		if err := callSiteTab.merge(cstab); err != nil {
+			base.FatalfAt(ic.Pos(), "%v", err)
+		}
+	} else {
+		callSiteTab = cstab
+	}
+}
+
+// ScoreCallsCleanup resets the state of the callsite cache
+// once ScoreCalls is done with a function.
+func ScoreCallsCleanup() {
+	if base.Debug.DumpInlCallSiteScores != 0 {
+		if allCallSites == nil {
+			allCallSites = make(CallSiteTab)
+		}
+		for call, cs := range callSiteTab {
+			allCallSites[call] = cs
+		}
+	}
+	for k := range scoreCallsCache.tab {
+		delete(scoreCallsCache.tab, k)
+	}
+}
+
+// GetCallSiteScore returns the previously calculated score for call
+// within fn.
+func GetCallSiteScore(fn *ir.Func, call *ir.CallExpr) (int, bool) {
+	if funcInlHeur, ok := fpmap[fn]; ok {
+		if cs, ok := funcInlHeur.cstab[call]; ok {
+			return cs.Score, true
+		}
+	}
+	if cs, ok := callSiteTab[call]; ok {
+		return cs.Score, true
+	}
+	return 0, false
+}
+
+// BudgetExpansion returns the amount to relax/expand the base
+// inlining budget when the new inliner is turned on; the inliner
+// will add the returned value to the hairiness budget.
+//
+// Background: with the new inliner, the score for a given callsite
+// can be adjusted down by some amount due to heuristics, however we
+// won't know whether this is going to happen until much later after
+// the CanInline call. This function returns the amount to relax the
+// budget initially (to allow for a large score adjustment); later on
+// in RevisitInlinability we'll look at each individual function to
+// demote it if needed.
+func BudgetExpansion(maxBudget int32) int32 {
+	if base.Debug.InlBudgetSlack != 0 {
+		return int32(base.Debug.InlBudgetSlack)
+	}
+	// In the default case, return maxBudget, which will effectively
+	// double the budget from 80 to 160; this should be good enough
+	// for most cases.
+	return maxBudget
+}
+
+var allCallSites CallSiteTab
+
+// DumpInlCallSiteScores is invoked by the inliner if the debug flag
+// "-d=dumpinlcallsitescores" is set; it dumps out a human-readable
+// summary of all (potentially) inlinable callsites in the package,
+// along with info on call site scoring and the adjustments made to a
+// given score. Here profile is the PGO profile in use (may be
+// nil), budgetCallback is a callback that can be invoked to find out
+// the original pre-adjustment hairiness limit for the function, and
+// inlineHotMaxBudget is the constant of the same name used in the
+// inliner. Sample output lines:
+//
+// Score  Adjustment  Status  Callee  CallerPos ScoreFlags
+// 115    40          DEMOTED cmd/compile/internal/abi.(*ABIParamAssignment).Offset     expand_calls.go:1679:14|6       panicPathAdj
+// 76     -5n         PROMOTED runtime.persistentalloc   mcheckmark.go:48:45|3   inLoopAdj
+// 201    0           --- PGO  unicode.DecodeRuneInString        utf8.go:312:30|1
+// 7      -5          --- PGO  internal/abi.Name.DataChecked     type.go:625:22|0        inLoopAdj
+//
+// In the dump above, "Score" is the final score calculated for the
+// callsite, "Adjustment" is the amount added to or subtracted from
+// the original hairiness estimate to form the score. "Status" shows
+// whether anything changed with the site -- did the adjustment bump
+// it down just below the threshold ("PROMOTED") or instead bump it
+// above the threshold ("DEMOTED"); this will be blank ("---") if no
+// threshold was crossed as a result of the heuristics. Note that
+// "Status" also shows whether PGO was involved. "Callee" is the name
+// of the function called, "CallerPos" is the position of the
+// callsite, and "ScoreFlags" is a digest of the specific properties
+// we used to make adjustments to callsite score via heuristics.
+func DumpInlCallSiteScores(profile *pgoir.Profile, budgetCallback func(fn *ir.Func, profile *pgoir.Profile) (int32, bool)) {
+
+	var indirectlyDueToPromotion func(cs *CallSite) bool
+	indirectlyDueToPromotion = func(cs *CallSite) bool {
+		bud, _ := budgetCallback(cs.Callee, profile)
+		hairyval := cs.Callee.Inl.Cost
+		score := int32(cs.Score)
+		if hairyval > bud && score <= bud {
+			return true
+		}
+		if cs.parent != nil {
+			return indirectlyDueToPromotion(cs.parent)
+		}
+		return false
+	}
+
+	genstatus := func(cs *CallSite) string {
+		hairyval := cs.Callee.Inl.Cost
+		bud, isPGO := budgetCallback(cs.Callee, profile)
+		score := int32(cs.Score)
+		st := "---"
+		expinl := false
+		switch {
+		case hairyval <= bud && score <= bud:
+			// "Normal" inlined case: hairy val sufficiently low that
+			// it would have been inlined anyway without heuristics.
+			expinl = true
+		case hairyval > bud && score > bud:
+			// "Normal" not inlined case: hairy val sufficiently high
+			// and scoring didn't lower it.
+		case hairyval > bud && score <= bud:
+			// Promoted: we would not have inlined it before, but
+			// after score adjustment we decided to inline.
+			st = "PROMOTED"
+			expinl = true
+		case hairyval <= bud && score > bud:
+			// Demoted: we would have inlined it before, but after
+			// score adjustment we decided not to inline.
+			st = "DEMOTED"
+		}
+		inlined := cs.aux&csAuxInlined != 0
+		indprom := false
+		if cs.parent != nil {
+			indprom = indirectlyDueToPromotion(cs.parent)
+		}
+		if inlined && indprom {
+			st += "|INDPROM"
+		}
+		if inlined && !expinl {
+			st += "|[NI?]"
+		} else if !inlined && expinl {
+			st += "|[IN?]"
+		}
+		if isPGO {
+			st += "|PGO"
+		}
+		return st
+	}
+
+	if base.Debug.DumpInlCallSiteScores != 0 {
+		var sl []*CallSite
+		for _, cs := range allCallSites {
+			sl = append(sl, cs)
+		}
+		sort.Slice(sl, func(i, j int) bool {
+			if sl[i].Score != sl[j].Score {
+				return sl[i].Score < sl[j].Score
+			}
+			fni := ir.PkgFuncName(sl[i].Callee)
+			fnj := ir.PkgFuncName(sl[j].Callee)
+			if fni != fnj {
+				return fni < fnj
+			}
+			ecsi := EncodeCallSiteKey(sl[i])
+			ecsj := EncodeCallSiteKey(sl[j])
+			return ecsi < ecsj
+		})
+
+		mkname := func(fn *ir.Func) string {
+			var n string
+			if fn == nil || fn.Nname == nil {
+				return "<nil>"
+			}
+			if fn.Sym().Pkg == types.LocalPkg {
+				n = "·" + fn.Sym().Name
+			} else {
+				n = ir.PkgFuncName(fn)
+			}
+			// don't try to print super-long names
+			if len(n) <= 64 {
+				return n
+			}
+			return n[:32] + "..." + n[len(n)-32:len(n)]
+		}
+
+		if len(sl) != 0 {
+			fmt.Fprintf(os.Stdout, "# scores for package %s\n", types.LocalPkg.Path)
+			fmt.Fprintf(os.Stdout, "# Score  Adjustment  Status  Callee  CallerPos Flags ScoreFlags\n")
+		}
+		for _, cs := range sl {
+			hairyval := cs.Callee.Inl.Cost
+			adj := int32(cs.Score) - hairyval
+			nm := mkname(cs.Callee)
+			ecc := EncodeCallSiteKey(cs)
+			fmt.Fprintf(os.Stdout, "%d  %d\t%s\t%s\t%s\t%s\n",
+				cs.Score, adj, genstatus(cs),
+				nm, ecc,
+				cs.ScoreMask.String())
+		}
+	}
+}

src/cmd/compile/internal/inline/inlheur/serialize.go

@@ -0,0 +1,80 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import "strings"
+
+func (funcProps *FuncProps) SerializeToString() string {
+	if funcProps == nil {
+		return ""
+	}
+	var sb strings.Builder
+	writeUleb128(&sb, uint64(funcProps.Flags))
+	writeUleb128(&sb, uint64(len(funcProps.ParamFlags)))
+	for _, pf := range funcProps.ParamFlags {
+		writeUleb128(&sb, uint64(pf))
+	}
+	writeUleb128(&sb, uint64(len(funcProps.ResultFlags)))
+	for _, rf := range funcProps.ResultFlags {
+		writeUleb128(&sb, uint64(rf))
+	}
+	return sb.String()
+}
+
+func DeserializeFromString(s string) *FuncProps {
+	if len(s) == 0 {
+		return nil
+	}
+	var funcProps FuncProps
+	var v uint64
+	sl := []byte(s)
+	v, sl = readULEB128(sl)
+	funcProps.Flags = FuncPropBits(v)
+	v, sl = readULEB128(sl)
+	funcProps.ParamFlags = make([]ParamPropBits, v)
+	for i := range funcProps.ParamFlags {
+		v, sl = readULEB128(sl)
+		funcProps.ParamFlags[i] = ParamPropBits(v)
+	}
+	v, sl = readULEB128(sl)
+	funcProps.ResultFlags = make([]ResultPropBits, v)
+	for i := range funcProps.ResultFlags {
+		v, sl = readULEB128(sl)
+		funcProps.ResultFlags[i] = ResultPropBits(v)
+	}
+	return &funcProps
+}
+
+func readULEB128(sl []byte) (value uint64, rsl []byte) {
+	var shift uint
+
+	for {
+		b := sl[0]
+		sl = sl[1:]
+		value |= (uint64(b&0x7F) << shift)
+		if b&0x80 == 0 {
+			break
+		}
+		shift += 7
+	}
+	return value, sl
+}
+
+func writeUleb128(sb *strings.Builder, v uint64) {
+	if v < 128 {
+		sb.WriteByte(uint8(v))
+		return
+	}
+	more := true
+	for more {
+		c := uint8(v & 0x7f)
+		v >>= 7
+		more = v != 0
+		if more {
+			c |= 0x80
+		}
+		sb.WriteByte(c)
+	}
+}

src/cmd/compile/internal/inline/inlheur/testdata/dumpscores.go

@@ -0,0 +1,45 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package dumpscores
+
+var G int
+
+func inlinable(x int, f func(int) int) int {
+	if x != 0 {
+		return 1
+	}
+	G += noninl(x)
+	return f(x)
+}
+
+func inlinable2(x int) int {
+	return noninl(-x)
+}
+
+//go:noinline
+func noninl(x int) int {
+	return x + 1
+}
+
+func tooLargeToInline(x int) int {
+	if x > 101 {
+		// Drive up the cost of inlining this func over the
+		// regular threshold.
+		return big(big(big(big(big(G + x)))))
+	}
+	if x < 100 {
+		// make sure this callsite is scored properly
+		G += inlinable(101, inlinable2)
+		if G == 101 {
+			return 0
+		}
+		panic(inlinable2(3))
+	}
+	return G
+}
+
+func big(q int) int {
+	return noninl(q) + noninl(-q)
+}

src/cmd/compile/internal/inline/inlheur/testdata/props/README.txt

@@ -0,0 +1,77 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+Notes on the format of the testcase files in
+cmd/compile/internal/inline/inlheur/testdata/props:
+
+- each (compilable) file contains input Go code and expected results
+  in the form of column-0 comments.
+
+- functions or methods that begin with "T_" are targeted for testing,
+  as well as "init" functions; all other functions are ignored.
+
+- function header comments begin with a line containing
+  the file name, function name, definition line, then index
+  and a count of the number of funcs that share that same
+  definition line (needed to support generics). Example:
+
+	  // foo.go T_mumble 35 1 4
+
+  Here "T_mumble" is defined at line 35, and it is func 0
+  out of the 4 funcs that share that same line.
+
+- function property expected results appear as comments in immediately
+  prior to the function. For example, here we have first the function
+  name ("T_feeds_if_simple"), then human-readable dump of the function
+  properties, as well as the JSON for the properties object, each
+  section separated by a "<>" delimiter.
+
+	  // params.go T_feeds_if_simple 35 0 1
+	  // RecvrParamFlags:
+	  //   0: ParamFeedsIfOrSwitch
+	  // <endpropsdump>
+	  // {"Flags":0,"RecvrParamFlags":[8],"ReturnFlags":[]}
+	  // callsite: params.go:34:10|0 "CallSiteOnPanicPath" 2
+	  // <endcallsites>
+	  // <endfuncpreamble>
+	  func T_feeds_if_simple(x int) {
+		if x < 100 {
+			os.Exit(1)
+		}
+		println(x)
+	}
+
+- when the test runs, it will compile the Go source file with an
+  option to dump out function properties, then compare the new dump
+  for each function with the JSON appearing in the header comment for
+  the function (in the example above, the JSON appears between
+  "<endpropsdump>" and "<endfuncpreamble>". The material prior to the
+  dump is simply there for human consumption, so that a developer can
+  easily see that "RecvrParamFlags":[8] means that the first parameter
+  has flag ParamFeedsIfOrSwitch.
+
+- when making changes to the compiler (which can alter the expected
+  results) or edits/additions to the go code in the testcase files,
+  you can remaster the results by running
+
+    go test -v -count=1 .
+
+  In the trace output of this run, you'll see messages of the form
+
+      === RUN   TestFuncProperties
+       funcprops_test.go:NNN: update-expected: emitted updated file
+                              testdata/props/XYZ.go.new
+       funcprops_test.go:MMM: please compare the two files, then overwrite
+                              testdata/props/XYZ.go with testdata/props/XYZ.go.new
+
+  at which point you can compare the old and new files by hand, then
+  overwrite the *.go file with the *.go.new file if you are happy with
+  the diffs.
+
+- note that the remastering process will strip out any existing
+  column-0 (unindented) comments; if you write comments that you
+  want to see preserved, use "/* */" or indent them.
+
+
+

src/cmd/compile/internal/inline/inlheur/testdata/props/acrosscall.go

@@ -0,0 +1,214 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// DO NOT EDIT (use 'go test -v -update-expected' instead.)
+// See cmd/compile/internal/inline/inlheur/testdata/props/README.txt
+// for more information on the format of this file.
+// <endfilepreamble>
+package params
+
+// acrosscall.go T_feeds_indirect_call_via_call_toplevel 19 0 1
+// ParamFlags
+//   0 ParamFeedsIndirectCall
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[8],"ResultFlags":null}
+// callsite: acrosscall.go:20:12|0 flagstr "" flagval 0 score 60 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_indirect_call_via_call_toplevel(f func(int)) {
+	callsparam(f)
+}
+
+// acrosscall.go T_feeds_indirect_call_via_call_conditional 31 0 1
+// ParamFlags
+//   0 ParamMayFeedIndirectCall
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[16],"ResultFlags":null}
+// callsite: acrosscall.go:33:13|0 flagstr "" flagval 0 score 60 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_indirect_call_via_call_conditional(f func(int)) {
+	if G != 101 {
+		callsparam(f)
+	}
+}
+
+// acrosscall.go T_feeds_conditional_indirect_call_via_call_toplevel 45 0 1
+// ParamFlags
+//   0 ParamMayFeedIndirectCall
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[16],"ResultFlags":null}
+// callsite: acrosscall.go:46:23|0 flagstr "" flagval 0 score 64 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_conditional_indirect_call_via_call_toplevel(f func(int)) {
+	callsparamconditional(f)
+}
+
+// acrosscall.go T_feeds_if_via_call 57 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":null}
+// callsite: acrosscall.go:58:9|0 flagstr "" flagval 0 score 8 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_via_call(x int) {
+	feedsif(x)
+}
+
+// acrosscall.go T_feeds_if_via_call_conditional 69 0 1
+// ParamFlags
+//   0 ParamMayFeedIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[64],"ResultFlags":null}
+// callsite: acrosscall.go:71:10|0 flagstr "" flagval 0 score 8 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_via_call_conditional(x int) {
+	if G != 101 {
+		feedsif(x)
+	}
+}
+
+// acrosscall.go T_feeds_conditional_if_via_call 83 0 1
+// ParamFlags
+//   0 ParamMayFeedIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[64],"ResultFlags":null}
+// callsite: acrosscall.go:84:20|0 flagstr "" flagval 0 score 12 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_conditional_if_via_call(x int) {
+	feedsifconditional(x)
+}
+
+// acrosscall.go T_multifeeds1 97 0 1
+// ParamFlags
+//   0 ParamFeedsIndirectCall|ParamMayFeedIndirectCall
+//   1 ParamNoInfo
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[24,0],"ResultFlags":null}
+// callsite: acrosscall.go:98:12|0 flagstr "" flagval 0 score 60 mask 0 maskstr ""
+// callsite: acrosscall.go:99:23|1 flagstr "" flagval 0 score 64 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_multifeeds1(f1, f2 func(int)) {
+	callsparam(f1)
+	callsparamconditional(f1)
+}
+
+// acrosscall.go T_acrosscall_returnsconstant 110 0 1
+// ResultFlags
+//   0 ResultAlwaysSameConstant
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":null,"ResultFlags":[8]}
+// callsite: acrosscall.go:111:24|0 flagstr "" flagval 0 score 2 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_acrosscall_returnsconstant() int {
+	return returnsconstant()
+}
+
+// acrosscall.go T_acrosscall_returnsmem 122 0 1
+// ResultFlags
+//   0 ResultIsAllocatedMem
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":null,"ResultFlags":[2]}
+// callsite: acrosscall.go:123:19|0 flagstr "" flagval 0 score 2 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_acrosscall_returnsmem() *int {
+	return returnsmem()
+}
+
+// acrosscall.go T_acrosscall_returnscci 134 0 1
+// ResultFlags
+//   0 ResultIsConcreteTypeConvertedToInterface
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":null,"ResultFlags":[4]}
+// callsite: acrosscall.go:135:19|0 flagstr "" flagval 0 score 7 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_acrosscall_returnscci() I {
+	return returnscci()
+}
+
+// acrosscall.go T_acrosscall_multiret 144 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":[0]}
+// callsite: acrosscall.go:146:25|0 flagstr "" flagval 0 score 2 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_acrosscall_multiret(q int) int {
+	if q != G {
+		return returnsconstant()
+	}
+	return 0
+}
+
+// acrosscall.go T_acrosscall_multiret2 158 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":[0]}
+// callsite: acrosscall.go:160:25|0 flagstr "" flagval 0 score 2 mask 0 maskstr ""
+// callsite: acrosscall.go:162:25|1 flagstr "" flagval 0 score 2 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_acrosscall_multiret2(q int) int {
+	if q == G {
+		return returnsconstant()
+	} else {
+		return returnsconstant()
+	}
+}
+
+func callsparam(f func(int)) {
+	f(2)
+}
+
+func callsparamconditional(f func(int)) {
+	if G != 101 {
+		f(2)
+	}
+}
+
+func feedsif(x int) int {
+	if x != 101 {
+		return 42
+	}
+	return 43
+}
+
+func feedsifconditional(x int) int {
+	if G != 101 {
+		if x != 101 {
+			return 42
+		}
+	}
+	return 43
+}
+
+func returnsconstant() int {
+	return 42
+}
+
+func returnsmem() *int {
+	return new(int)
+}
+
+func returnscci() I {
+	var q Q
+	return q
+}
+
+type I interface {
+	Foo()
+}
+
+type Q int
+
+func (q Q) Foo() {
+}
+
+var G int

src/cmd/compile/internal/inline/inlheur/testdata/props/calls.go

@@ -0,0 +1,240 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// DO NOT EDIT (use 'go test -v -update-expected' instead.)
+// See cmd/compile/internal/inline/inlheur/testdata/props/README.txt
+// for more information on the format of this file.
+// <endfilepreamble>
+package calls
+
+import "os"
+
+// calls.go T_call_in_panic_arg 19 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// callsite: calls.go:21:15|0 flagstr "CallSiteOnPanicPath" flagval 2 score 42 mask 1 maskstr "panicPathAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_call_in_panic_arg(x int) {
+	if x < G {
+		panic(callee(x))
+	}
+}
+
+// calls.go T_calls_in_loops 32 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":null}
+// callsite: calls.go:34:9|0 flagstr "CallSiteInLoop" flagval 1 score -3 mask 4 maskstr "inLoopAdj"
+// callsite: calls.go:37:9|1 flagstr "CallSiteInLoop" flagval 1 score -3 mask 4 maskstr "inLoopAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_calls_in_loops(x int, q []string) {
+	for i := 0; i < x; i++ {
+		callee(i)
+	}
+	for _, s := range q {
+		callee(len(s))
+	}
+}
+
+// calls.go T_calls_in_pseudo_loop 48 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":null}
+// callsite: calls.go:50:9|0 flagstr "" flagval 0 score 2 mask 0 maskstr ""
+// callsite: calls.go:54:9|1 flagstr "" flagval 0 score 2 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_calls_in_pseudo_loop(x int, q []string) {
+	for i := 0; i < x; i++ {
+		callee(i)
+		return
+	}
+	for _, s := range q {
+		callee(len(s))
+		break
+	}
+}
+
+// calls.go T_calls_on_panic_paths 67 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":null}
+// callsite: calls.go:69:9|0 flagstr "CallSiteOnPanicPath" flagval 2 score 42 mask 1 maskstr "panicPathAdj"
+// callsite: calls.go:73:9|1 flagstr "CallSiteOnPanicPath" flagval 2 score 42 mask 1 maskstr "panicPathAdj"
+// callsite: calls.go:77:12|2 flagstr "CallSiteOnPanicPath" flagval 2 score 102 mask 1 maskstr "panicPathAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_calls_on_panic_paths(x int, q []string) {
+	if x+G == 101 {
+		callee(x)
+		panic("ouch")
+	}
+	if x < G-101 {
+		callee(x)
+		if len(q) == 0 {
+			G++
+		}
+		callsexit(x)
+	}
+}
+
+// calls.go T_calls_not_on_panic_paths 93 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch|ParamMayFeedIfOrSwitch
+//   1 ParamNoInfo
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[96,0],"ResultFlags":null}
+// callsite: calls.go:103:9|0 flagstr "" flagval 0 score 2 mask 0 maskstr ""
+// callsite: calls.go:112:9|1 flagstr "" flagval 0 score 2 mask 0 maskstr ""
+// callsite: calls.go:115:9|2 flagstr "" flagval 0 score 2 mask 0 maskstr ""
+// callsite: calls.go:119:12|3 flagstr "CallSiteOnPanicPath" flagval 2 score 102 mask 1 maskstr "panicPathAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_calls_not_on_panic_paths(x int, q []string) {
+	if x != G {
+		panic("ouch")
+		/* Notes: */
+		/* - we only look for post-dominating panic/exit, so */
+		/*   this site will on fact not have a panicpath flag */
+		/* - vet will complain about this site as unreachable */
+		callee(x)
+	}
+	if x != G {
+		callee(x)
+		if x < 100 {
+			panic("ouch")
+		}
+	}
+	if x+G == 101 {
+		if x < 100 {
+			panic("ouch")
+		}
+		callee(x)
+	}
+	if x < -101 {
+		callee(x)
+		if len(q) == 0 {
+			return
+		}
+		callsexit(x)
+	}
+}
+
+// calls.go init.0 129 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":null,"ResultFlags":null}
+// callsite: calls.go:130:16|0 flagstr "CallSiteInInitFunc" flagval 4 score 22 mask 2 maskstr "initFuncAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func init() {
+	println(callee(5))
+}
+
+// calls.go T_pass_inlinable_func_to_param_feeding_indirect_call 140 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":[0]}
+// callsite: calls.go:141:19|0 flagstr "" flagval 0 score 16 mask 512 maskstr "passInlinableFuncToIndCallAdj"
+// callsite: calls.go:141:19|calls.go:232:10|0 flagstr "" flagval 0 score 2 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_pass_inlinable_func_to_param_feeding_indirect_call(x int) int {
+	return callsParam(x, callee)
+}
+
+// calls.go T_pass_noninlinable_func_to_param_feeding_indirect_call 150 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":[0]}
+// callsite: calls.go:153:19|0 flagstr "" flagval 0 score 36 mask 128 maskstr "passFuncToIndCallAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_pass_noninlinable_func_to_param_feeding_indirect_call(x int) int {
+	// if we inline callsParam we can convert the indirect call
+	// to a direct call, but we can't inline it.
+	return callsParam(x, calleeNoInline)
+}
+
+// calls.go T_pass_inlinable_func_to_param_feeding_nested_indirect_call 165 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":[0]}
+// callsite: calls.go:166:25|0 flagstr "" flagval 0 score 27 mask 1024 maskstr "passInlinableFuncToNestedIndCallAdj"
+// callsite: calls.go:166:25|calls.go:237:11|0 flagstr "" flagval 0 score 2 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_pass_inlinable_func_to_param_feeding_nested_indirect_call(x int) int {
+	return callsParamNested(x, callee)
+}
+
+// calls.go T_pass_noninlinable_func_to_param_feeding_nested_indirect_call 177 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":[0]}
+// callsite: calls.go:178:25|0 flagstr "" flagval 0 score 47 mask 256 maskstr "passFuncToNestedIndCallAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_pass_noninlinable_func_to_param_feeding_nested_indirect_call(x int) int {
+	return callsParamNested(x, calleeNoInline)
+}
+
+// calls.go T_call_scoring_in_noninlinable_func 195 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":[0]}
+// callsite: calls.go:209:14|0 flagstr "CallSiteOnPanicPath" flagval 2 score 42 mask 1 maskstr "panicPathAdj"
+// callsite: calls.go:210:15|1 flagstr "CallSiteOnPanicPath" flagval 2 score 42 mask 1 maskstr "panicPathAdj"
+// callsite: calls.go:212:19|2 flagstr "" flagval 0 score 16 mask 512 maskstr "passInlinableFuncToIndCallAdj"
+// callsite: calls.go:212:19|calls.go:232:10|0 flagstr "" flagval 0 score 4 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+// calls.go T_call_scoring_in_noninlinable_func.func1 212 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":[0]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_call_scoring_in_noninlinable_func(x int, sl []int) int {
+	if x == 101 {
+		// Drive up the cost of inlining this funcfunc over the
+		// regular threshold.
+		for i := 0; i < 10; i++ {
+			for j := 0; j < i; j++ {
+				sl = append(sl, append(sl, append(sl, append(sl, x)...)...)...)
+				sl = append(sl, sl[0], sl[1], sl[2])
+				x += calleeNoInline(x)
+			}
+		}
+	}
+	if x < 100 {
+		// make sure this callsite is scored properly
+		G += callee(101)
+		panic(callee(x))
+	}
+	return callsParam(x, func(y int) int { return y + x })
+}
+
+var G int
+
+func callee(x int) int {
+	return x
+}
+
+func calleeNoInline(x int) int {
+	defer func() { G++ }()
+	return x
+}
+
+func callsexit(x int) {
+	println(x)
+	os.Exit(x)
+}
+
+func callsParam(x int, f func(int) int) int {
+	return f(x)
+}
+
+func callsParamNested(x int, f func(int) int) int {
+	if x < 0 {
+		return f(x)
+	}
+	return 0
+}

src/cmd/compile/internal/inline/inlheur/testdata/props/funcflags.go

@@ -0,0 +1,341 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// DO NOT EDIT (use 'go test -v -update-expected' instead.)
+// See cmd/compile/internal/inline/inlheur/testdata/props/README.txt
+// for more information on the format of this file.
+// <endfilepreamble>
+
+package funcflags
+
+import "os"
+
+// funcflags.go T_simple 20 0 1
+// Flags FuncPropNeverReturns
+// <endpropsdump>
+// {"Flags":1,"ParamFlags":null,"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_simple() {
+	panic("bad")
+}
+
+// funcflags.go T_nested 32 0 1
+// Flags FuncPropNeverReturns
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":1,"ParamFlags":[32],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_nested(x int) {
+	if x < 10 {
+		panic("bad")
+	} else {
+		panic("good")
+	}
+}
+
+// funcflags.go T_block1 46 0 1
+// Flags FuncPropNeverReturns
+// <endpropsdump>
+// {"Flags":1,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_block1(x int) {
+	panic("bad")
+	if x < 10 {
+		return
+	}
+}
+
+// funcflags.go T_block2 60 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_block2(x int) {
+	if x < 10 {
+		return
+	}
+	panic("bad")
+}
+
+// funcflags.go T_switches1 75 0 1
+// Flags FuncPropNeverReturns
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":1,"ParamFlags":[32],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_switches1(x int) {
+	switch x {
+	case 1:
+		panic("one")
+	case 2:
+		panic("two")
+	}
+	panic("whatev")
+}
+
+// funcflags.go T_switches1a 92 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_switches1a(x int) {
+	switch x {
+	case 2:
+		panic("two")
+	}
+}
+
+// funcflags.go T_switches2 106 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_switches2(x int) {
+	switch x {
+	case 1:
+		panic("one")
+	case 2:
+		panic("two")
+	default:
+		return
+	}
+	panic("whatev")
+}
+
+// funcflags.go T_switches3 123 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_switches3(x interface{}) {
+	switch x.(type) {
+	case bool:
+		panic("one")
+	case float32:
+		panic("two")
+	}
+}
+
+// funcflags.go T_switches4 138 0 1
+// Flags FuncPropNeverReturns
+// <endpropsdump>
+// {"Flags":1,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_switches4(x int) {
+	switch x {
+	case 1:
+		x++
+		fallthrough
+	case 2:
+		panic("two")
+		fallthrough
+	default:
+		panic("bad")
+	}
+	panic("whatev")
+}
+
+// funcflags.go T_recov 157 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_recov(x int) {
+	if x := recover(); x != nil {
+		panic(x)
+	}
+}
+
+// funcflags.go T_forloops1 169 0 1
+// Flags FuncPropNeverReturns
+// <endpropsdump>
+// {"Flags":1,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_forloops1(x int) {
+	for {
+		panic("wokketa")
+	}
+}
+
+// funcflags.go T_forloops2 180 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_forloops2(x int) {
+	for {
+		println("blah")
+		if true {
+			break
+		}
+		panic("warg")
+	}
+}
+
+// funcflags.go T_forloops3 195 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_forloops3(x int) {
+	for i := 0; i < 101; i++ {
+		println("blah")
+		if true {
+			continue
+		}
+		panic("plark")
+	}
+	for i := range [10]int{} {
+		println(i)
+		panic("plark")
+	}
+	panic("whatev")
+}
+
+// funcflags.go T_hasgotos 215 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_hasgotos(x int, y int) {
+	{
+		xx := x
+		panic("bad")
+	lab1:
+		goto lab2
+	lab2:
+		if false {
+			goto lab1
+		} else {
+			goto lab4
+		}
+	lab4:
+		if xx < y {
+		lab3:
+			if false {
+				goto lab3
+			}
+		}
+		println(9)
+	}
+}
+
+// funcflags.go T_break_with_label 246 0 1
+// ParamFlags
+//   0 ParamMayFeedIfOrSwitch
+//   1 ParamNoInfo
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[64,0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_break_with_label(x int, y int) {
+	// presence of break with label should pessimize this func
+	// (similar to goto).
+	panic("bad")
+lab1:
+	for {
+		println("blah")
+		if x < 0 {
+			break lab1
+		}
+		panic("hubba")
+	}
+}
+
+// funcflags.go T_callsexit 268 0 1
+// Flags FuncPropNeverReturns
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":1,"ParamFlags":[32],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_callsexit(x int) {
+	if x < 0 {
+		os.Exit(1)
+	}
+	os.Exit(2)
+}
+
+// funcflags.go T_exitinexpr 281 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// callsite: funcflags.go:286:18|0 flagstr "CallSiteOnPanicPath" flagval 2 score 102 mask 1 maskstr "panicPathAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_exitinexpr(x int) {
+	// This function does indeed unconditionally call exit, since the
+	// first thing it does is invoke exprcallsexit, however from the
+	// perspective of this function, the call is not at the statement
+	// level, so we'll wind up missing it.
+	if exprcallsexit(x) < 0 {
+		println("foo")
+	}
+}
+
+// funcflags.go T_select_noreturn 297 0 1
+// Flags FuncPropNeverReturns
+// <endpropsdump>
+// {"Flags":1,"ParamFlags":[0,0,0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_select_noreturn(chi chan int, chf chan float32, p *int) {
+	rv := 0
+	select {
+	case i := <-chi:
+		rv = i
+	case f := <-chf:
+		rv = int(f)
+	}
+	*p = rv
+	panic("bad")
+}
+
+// funcflags.go T_select_mayreturn 314 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0,0],"ResultFlags":[0]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_select_mayreturn(chi chan int, chf chan float32, p *int) int {
+	rv := 0
+	select {
+	case i := <-chi:
+		rv = i
+		return i
+	case f := <-chf:
+		rv = int(f)
+	}
+	*p = rv
+	panic("bad")
+}
+
+// funcflags.go T_calls_callsexit 334 0 1
+// Flags FuncPropNeverReturns
+// <endpropsdump>
+// {"Flags":1,"ParamFlags":[0],"ResultFlags":null}
+// callsite: funcflags.go:335:15|0 flagstr "CallSiteOnPanicPath" flagval 2 score 102 mask 1 maskstr "panicPathAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_calls_callsexit(x int) {
+	exprcallsexit(x)
+}
+
+func exprcallsexit(x int) int {
+	os.Exit(x)
+	return x
+}

src/cmd/compile/internal/inline/inlheur/testdata/props/params.go

@@ -0,0 +1,367 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// DO NOT EDIT (use 'go test -v -update-expected' instead.)
+// See cmd/compile/internal/inline/inlheur/testdata/props/README.txt
+// for more information on the format of this file.
+// <endfilepreamble>
+package params
+
+import "os"
+
+// params.go T_feeds_if_simple 20 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_simple(x int) {
+	if x < 100 {
+		os.Exit(1)
+	}
+	println(x)
+}
+
+// params.go T_feeds_if_nested 35 0 1
+// ParamFlags
+//   0 ParamMayFeedIfOrSwitch
+//   1 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[64,32],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_nested(x, y int) {
+	if y != 0 {
+		if x < 100 {
+			os.Exit(1)
+		}
+	}
+	println(x)
+}
+
+// params.go T_feeds_if_pointer 51 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_pointer(xp *int) {
+	if xp != nil {
+		os.Exit(1)
+	}
+	println(xp)
+}
+
+// params.go T.T_feeds_if_simple_method 66 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+//   1 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32,32],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func (r T) T_feeds_if_simple_method(x int) {
+	if x < 100 {
+		os.Exit(1)
+	}
+	if r != 99 {
+		os.Exit(2)
+	}
+	println(x)
+}
+
+// params.go T_feeds_if_blanks 86 0 1
+// ParamFlags
+//   0 ParamNoInfo
+//   1 ParamFeedsIfOrSwitch
+//   2 ParamNoInfo
+//   3 ParamNoInfo
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,32,0,0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_blanks(_ string, x int, _ bool, _ bool) {
+	// blanks ignored; from a props perspective "x" is param 0
+	if x < 100 {
+		os.Exit(1)
+	}
+	println(x)
+}
+
+// params.go T_feeds_if_with_copy 101 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_with_copy(x int) {
+	// simple copy here -- we get this case
+	xx := x
+	if xx < 100 {
+		os.Exit(1)
+	}
+	println(x)
+}
+
+// params.go T_feeds_if_with_copy_expr 115 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_with_copy_expr(x int) {
+	// this case (copy of expression) currently not handled.
+	xx := x < 100
+	if xx {
+		os.Exit(1)
+	}
+	println(x)
+}
+
+// params.go T_feeds_switch 131 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_switch(x int) {
+	switch x {
+	case 101:
+		println(101)
+	case 202:
+		panic("bad")
+	}
+	println(x)
+}
+
+// params.go T_feeds_if_toocomplex 146 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_toocomplex(x int, y int) {
+	// not handled at the moment; we only look for cases where
+	// an "if" or "switch" can be simplified based on a single
+	// constant param, not a combination of constant params.
+	if x < y {
+		panic("bad")
+	}
+	println(x + y)
+}
+
+// params.go T_feeds_if_redefined 161 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_redefined(x int) {
+	if x < G {
+		x++
+	}
+	if x == 101 {
+		panic("bad")
+	}
+}
+
+// params.go T_feeds_if_redefined2 175 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_redefined2(x int) {
+	// this currently classifies "x" as "no info", since the analysis we
+	// use to check for reassignments/redefinitions is not flow-sensitive,
+	// but we could probably catch this case with better analysis or
+	// high-level SSA.
+	if x == 101 {
+		panic("bad")
+	}
+	if x < G {
+		x++
+	}
+}
+
+// params.go T_feeds_multi_if 196 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+//   1 ParamNoInfo
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32,0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_multi_if(x int, y int) {
+	// Here we have one "if" that is too complex (x < y) but one that is
+	// simple enough. Currently we enable the heuristic for this. It's
+	// possible to imagine this being a bad thing if the function in
+	// question is sufficiently large, but if it's too large we probably
+	// can't inline it anyhow.
+	if x < y {
+		panic("bad")
+	}
+	if x < 10 {
+		panic("whatev")
+	}
+	println(x + y)
+}
+
+// params.go T_feeds_if_redefined_indirectwrite 216 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_redefined_indirectwrite(x int) {
+	ax := &x
+	if G != 2 {
+		*ax = G
+	}
+	if x == 101 {
+		panic("bad")
+	}
+}
+
+// params.go T_feeds_if_redefined_indirectwrite_copy 231 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_redefined_indirectwrite_copy(x int) {
+	// we don't catch this case, "x" is marked as no info,
+	// since we're conservative about redefinitions.
+	ax := &x
+	cx := x
+	if G != 2 {
+		*ax = G
+	}
+	if cx == 101 {
+		panic("bad")
+	}
+}
+
+// params.go T_feeds_if_expr1 251 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_expr1(x int) {
+	if x == 101 || x == 102 || x&0xf == 0 {
+		panic("bad")
+	}
+}
+
+// params.go T_feeds_if_expr2 262 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_expr2(x int) {
+	if (x*x)-(x+x)%x == 101 || x&0xf == 0 {
+		panic("bad")
+	}
+}
+
+// params.go T_feeds_if_expr3 273 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_expr3(x int) {
+	if x-(x&0x1)^378 > (1 - G) {
+		panic("bad")
+	}
+}
+
+// params.go T_feeds_if_shift_may_panic 284 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":[0]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_shift_may_panic(x int) *int {
+	// here if "x" is a constant like 2, we could simplify the "if",
+	// but if we were to pass in a negative value for "x" we can't
+	// fold the condition due to the need to panic on negative shift.
+	if 1<<x > 1024 {
+		return nil
+	}
+	return &G
+}
+
+// params.go T_feeds_if_maybe_divide_by_zero 299 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_if_maybe_divide_by_zero(x int) {
+	if 99/x == 3 {
+		return
+	}
+	println("blarg")
+}
+
+// params.go T_feeds_indcall 313 0 1
+// ParamFlags
+//   0 ParamMayFeedIndirectCall
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[16],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_indcall(x func()) {
+	if G != 20 {
+		x()
+	}
+}
+
+// params.go T_feeds_indcall_and_if 326 0 1
+// ParamFlags
+//   0 ParamMayFeedIndirectCall|ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[48],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_indcall_and_if(x func()) {
+	if x != nil {
+		x()
+	}
+}
+
+// params.go T_feeds_indcall_with_copy 339 0 1
+// ParamFlags
+//   0 ParamFeedsIndirectCall
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[8],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_indcall_with_copy(x func()) {
+	xx := x
+	if G < 10 {
+		G--
+	}
+	xx()
+}
+
+// params.go T_feeds_interface_method_call 354 0 1
+// ParamFlags
+//   0 ParamFeedsInterfaceMethodCall
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[2],"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_feeds_interface_method_call(i I) {
+	i.Blarg()
+}
+
+var G int
+
+type T int
+
+type I interface {
+	Blarg()
+}
+
+func (r T) Blarg() {
+}

src/cmd/compile/internal/inline/inlheur/testdata/props/returns.go

@@ -0,0 +1,370 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// DO NOT EDIT (use 'go test -v -update-expected' instead.)
+// See cmd/compile/internal/inline/inlheur/testdata/props/README.txt
+// for more information on the format of this file.
+// <endfilepreamble>
+
+package returns1
+
+import "unsafe"
+
+// returns.go T_simple_allocmem 21 0 1
+// ResultFlags
+//   0 ResultIsAllocatedMem
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":null,"ResultFlags":[2]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_simple_allocmem() *Bar {
+	return &Bar{}
+}
+
+// returns.go T_allocmem_two_returns 34 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// ResultFlags
+//   0 ResultIsAllocatedMem
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":[2]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_allocmem_two_returns(x int) *Bar {
+	// multiple returns
+	if x < 0 {
+		return new(Bar)
+	} else {
+		return &Bar{x: 2}
+	}
+}
+
+// returns.go T_allocmem_three_returns 52 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// ResultFlags
+//   0 ResultIsAllocatedMem
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":[2]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_allocmem_three_returns(x int) []*Bar {
+	// more multiple returns
+	switch x {
+	case 10, 11, 12:
+		return make([]*Bar, 10)
+	case 13:
+		fallthrough
+	case 15:
+		return []*Bar{&Bar{x: 15}}
+	}
+	return make([]*Bar, 0, 10)
+}
+
+// returns.go T_return_nil 72 0 1
+// ResultFlags
+//   0 ResultAlwaysSameConstant
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":null,"ResultFlags":[8]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_return_nil() *Bar {
+	// simple case: no alloc
+	return nil
+}
+
+// returns.go T_multi_return_nil 84 0 1
+// ResultFlags
+//   0 ResultAlwaysSameConstant
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":[8]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_multi_return_nil(x, y bool) *Bar {
+	if x && y {
+		return nil
+	}
+	return nil
+}
+
+// returns.go T_multi_return_nil_anomoly 98 0 1
+// ResultFlags
+//   0 ResultIsConcreteTypeConvertedToInterface
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":[4]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_multi_return_nil_anomoly(x, y bool) Itf {
+	if x && y {
+		var qnil *Q
+		return qnil
+	}
+	var barnil *Bar
+	return barnil
+}
+
+// returns.go T_multi_return_some_nil 112 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":[0]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_multi_return_some_nil(x, y bool) *Bar {
+	if x && y {
+		return nil
+	} else {
+		return &GB
+	}
+}
+
+// returns.go T_mixed_returns 127 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":[0]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_mixed_returns(x int) *Bar {
+	// mix of alloc and non-alloc
+	if x < 0 {
+		return new(Bar)
+	} else {
+		return &GB
+	}
+}
+
+// returns.go T_mixed_returns_slice 143 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":[0]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_mixed_returns_slice(x int) []*Bar {
+	// mix of alloc and non-alloc
+	switch x {
+	case 10, 11, 12:
+		return make([]*Bar, 10)
+	case 13:
+		fallthrough
+	case 15:
+		return []*Bar{&Bar{x: 15}}
+	}
+	ba := [...]*Bar{&GB, &GB}
+	return ba[:]
+}
+
+// returns.go T_maps_and_channels 167 0 1
+// ResultFlags
+//   0 ResultNoInfo
+//   1 ResultNoInfo
+//   2 ResultNoInfo
+//   3 ResultAlwaysSameConstant
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":[0,0,0,8]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_maps_and_channels(x int, b bool) (bool, map[int]int, chan bool, unsafe.Pointer) {
+	// maps and channels
+	return b, make(map[int]int), make(chan bool), nil
+}
+
+// returns.go T_assignment_to_named_returns 179 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":[0,0]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_assignment_to_named_returns(x int) (r1 *uint64, r2 *uint64) {
+	// assignments to named returns and then "return" not supported
+	r1 = new(uint64)
+	if x < 1 {
+		*r1 = 2
+	}
+	r2 = new(uint64)
+	return
+}
+
+// returns.go T_named_returns_but_return_explicit_values 199 0 1
+// ParamFlags
+//   0 ParamFeedsIfOrSwitch
+// ResultFlags
+//   0 ResultIsAllocatedMem
+//   1 ResultIsAllocatedMem
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[32],"ResultFlags":[2,2]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_named_returns_but_return_explicit_values(x int) (r1 *uint64, r2 *uint64) {
+	// named returns ok if all returns are non-empty
+	rx1 := new(uint64)
+	if x < 1 {
+		*rx1 = 2
+	}
+	rx2 := new(uint64)
+	return rx1, rx2
+}
+
+// returns.go T_return_concrete_type_to_itf 216 0 1
+// ResultFlags
+//   0 ResultIsConcreteTypeConvertedToInterface
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":[4]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_return_concrete_type_to_itf(x, y int) Itf {
+	return &Bar{}
+}
+
+// returns.go T_return_concrete_type_to_itfwith_copy 227 0 1
+// ResultFlags
+//   0 ResultIsConcreteTypeConvertedToInterface
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":[4]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_return_concrete_type_to_itfwith_copy(x, y int) Itf {
+	b := &Bar{}
+	println("whee")
+	return b
+}
+
+// returns.go T_return_concrete_type_to_itf_mixed 238 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":[0]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_return_concrete_type_to_itf_mixed(x, y int) Itf {
+	if x < y {
+		b := &Bar{}
+		return b
+	}
+	return nil
+}
+
+// returns.go T_return_same_func 253 0 1
+// ResultFlags
+//   0 ResultAlwaysSameInlinableFunc
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":null,"ResultFlags":[32]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_return_same_func() func(int) int {
+	if G < 10 {
+		return foo
+	} else {
+		return foo
+	}
+}
+
+// returns.go T_return_different_funcs 266 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":null,"ResultFlags":[0]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_return_different_funcs() func(int) int {
+	if G != 10 {
+		return foo
+	} else {
+		return bar
+	}
+}
+
+// returns.go T_return_same_closure 286 0 1
+// ResultFlags
+//   0 ResultAlwaysSameInlinableFunc
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":null,"ResultFlags":[32]}
+// <endcallsites>
+// <endfuncpreamble>
+// returns.go T_return_same_closure.func1 287 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":[0]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_return_same_closure() func(int) int {
+	p := func(q int) int { return q }
+	if G < 10 {
+		return p
+	} else {
+		return p
+	}
+}
+
+// returns.go T_return_different_closures 312 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":null,"ResultFlags":[0]}
+// <endcallsites>
+// <endfuncpreamble>
+// returns.go T_return_different_closures.func1 313 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":[0]}
+// <endcallsites>
+// <endfuncpreamble>
+// returns.go T_return_different_closures.func2 317 0 1
+// ResultFlags
+//   0 ResultAlwaysSameConstant
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":[8]}
+// <endcallsites>
+// <endfuncpreamble>
+func T_return_different_closures() func(int) int {
+	p := func(q int) int { return q }
+	if G < 10 {
+		return p
+	} else {
+		return func(q int) int { return 101 }
+	}
+}
+
+// returns.go T_return_noninlinable 339 0 1
+// ResultFlags
+//   0 ResultAlwaysSameFunc
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":[16]}
+// <endcallsites>
+// <endfuncpreamble>
+// returns.go T_return_noninlinable.func1 340 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":[0]}
+// callsite: returns.go:343:4|0 flagstr "" flagval 0 score 4 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+// returns.go T_return_noninlinable.func1.1 341 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":null,"ResultFlags":null}
+// <endcallsites>
+// <endfuncpreamble>
+func T_return_noninlinable(x int) func(int) int {
+	noti := func(q int) int {
+		defer func() {
+			println(q + x)
+		}()
+		return q
+	}
+	return noti
+}
+
+type Bar struct {
+	x int
+	y string
+}
+
+func (b *Bar) Plark() {
+}
+
+type Q int
+
+func (q *Q) Plark() {
+}
+
+func foo(x int) int { return x }
+func bar(x int) int { return -x }
+
+var G int
+var GB Bar
+
+type Itf interface {
+	Plark()
+}

src/cmd/compile/internal/inline/inlheur/testdata/props/returns2.go

@@ -0,0 +1,231 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// DO NOT EDIT (use 'go test -v -update-expected' instead.)
+// See cmd/compile/internal/inline/inlheur/testdata/props/README.txt
+// for more information on the format of this file.
+// <endfilepreamble>
+
+package returns2
+
+// returns2.go T_return_feeds_iface_call 18 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":null,"ResultFlags":null}
+// callsite: returns2.go:19:13|0 flagstr "" flagval 0 score 1 mask 16384 maskstr "returnFeedsConcreteToInterfaceCallAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_return_feeds_iface_call() {
+	b := newBar(10)
+	b.Plark()
+}
+
+// returns2.go T_multi_return_feeds_iface_call 29 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":null,"ResultFlags":null}
+// callsite: returns2.go:30:20|0 flagstr "" flagval 0 score 3 mask 16384 maskstr "returnFeedsConcreteToInterfaceCallAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_multi_return_feeds_iface_call() {
+	_, b, _ := newBar2(10)
+	b.Plark()
+}
+
+// returns2.go T_returned_inlinable_func_feeds_indirect_call 41 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// callsite: returns2.go:42:18|0 flagstr "" flagval 0 score -51 mask 8200 maskstr "passConstToIfAdj|returnFeedsInlinableFuncToIndCallAdj"
+// callsite: returns2.go:44:20|1 flagstr "" flagval 0 score -23 mask 8192 maskstr "returnFeedsInlinableFuncToIndCallAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_returned_inlinable_func_feeds_indirect_call(q int) {
+	f := returnsFunc(10)
+	f(q)
+	f2 := returnsFunc2()
+	f2(q)
+}
+
+// returns2.go T_returned_noninlineable_func_feeds_indirect_call 54 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// callsite: returns2.go:55:30|0 flagstr "" flagval 0 score -23 mask 4096 maskstr "returnFeedsFuncToIndCallAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_returned_noninlineable_func_feeds_indirect_call(q int) {
+	f := returnsNonInlinableFunc()
+	f(q)
+}
+
+// returns2.go T_multi_return_feeds_indirect_call 65 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":null}
+// callsite: returns2.go:66:29|0 flagstr "" flagval 0 score -21 mask 8192 maskstr "returnFeedsInlinableFuncToIndCallAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_multi_return_feeds_indirect_call(q int) {
+	_, f, _ := multiReturnsFunc()
+	f(q)
+}
+
+// returns2.go T_return_feeds_ifswitch 76 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":[0]}
+// callsite: returns2.go:77:14|0 flagstr "" flagval 0 score 10 mask 2048 maskstr "returnFeedsConstToIfAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_return_feeds_ifswitch(q int) int {
+	x := meaning(q)
+	if x < 42 {
+		switch x {
+		case 42:
+			return 1
+		}
+	}
+	return 0
+}
+
+// returns2.go T_multi_return_feeds_ifswitch 93 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":[0]}
+// callsite: returns2.go:94:21|0 flagstr "" flagval 0 score 9 mask 2048 maskstr "returnFeedsConstToIfAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_multi_return_feeds_ifswitch(q int) int {
+	x, y, z := meanings(q)
+	if x < y {
+		switch x {
+		case 42:
+			return z
+		}
+	}
+	return 0
+}
+
+// returns2.go T_two_calls_feed_ifswitch 111 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0],"ResultFlags":[0]}
+// callsite: returns2.go:115:14|0 flagstr "" flagval 0 score 25 mask 0 maskstr ""
+// callsite: returns2.go:116:14|1 flagstr "" flagval 0 score 25 mask 0 maskstr ""
+// <endcallsites>
+// <endfuncpreamble>
+func T_two_calls_feed_ifswitch(q int) int {
+	// This case we don't handle; for the heuristic to kick in,
+	// all names in a given if/switch cond have to come from the
+	// same callsite
+	x := meaning(q)
+	y := meaning(-q)
+	if x < y {
+		switch x + y {
+		case 42:
+			return 1
+		}
+	}
+	return 0
+}
+
+// returns2.go T_chained_indirect_call 132 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":null}
+// callsite: returns2.go:135:18|0 flagstr "" flagval 0 score -31 mask 8192 maskstr "returnFeedsInlinableFuncToIndCallAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_chained_indirect_call(x, y int) {
+	// Here 'returnsFunc' returns an inlinable func that feeds
+	// directly into a call (no named intermediate).
+	G += returnsFunc(x - y)(x + y)
+}
+
+// returns2.go T_chained_conc_iface_call 144 0 1
+// <endpropsdump>
+// {"Flags":0,"ParamFlags":[0,0],"ResultFlags":null}
+// callsite: returns2.go:148:8|0 flagstr "" flagval 0 score 1 mask 16384 maskstr "returnFeedsConcreteToInterfaceCallAdj"
+// <endcallsites>
+// <endfuncpreamble>
+func T_chained_conc_iface_call(x, y int) {
+	// Similar to the case above, return from call returning concrete type
+	// feeds directly into interface call. Note that only the first
+	// iface call is interesting here.
+	newBar(10).Plark().Plark()
+}
+
+func returnsFunc(x int) func(int) int {
+	if x < 0 {
+		G++
+	}
+	return adder
+}
+
+func returnsFunc2() func(int) int {
+	return func(x int) int {
+		return adder(x)
+	}
+}
+
+func returnsNonInlinableFunc() func(int) int {
+	return adderNoInline
+}
+
+func multiReturnsFunc() (int, func(int) int, int) {
+	return 42, func(x int) int { G++; return 1 }, -42
+}
+
+func adder(x int) int {
+	G += 1
+	return G
+}
+
+func adderNoInline(x int) int {
+	defer func() { G += x }()
+	G += 1
+	return G
+}
+
+func meaning(q int) int {
+	r := 0
+	for i := 0; i < 42; i++ {
+		r += q
+	}
+	G += r
+	return 42
+}
+
+func meanings(q int) (int, int, int) {
+	r := 0
+	for i := 0; i < 42; i++ {
+		r += q
+	}
+	return 42, 43, r
+}
+
+type Bar struct {
+	x int
+	y string
+}
+
+func (b *Bar) Plark() Itf {
+	return b
+}
+
+type Itf interface {
+	Plark() Itf
+}
+
+func newBar(x int) Itf {
+	s := 0
+	for i := 0; i < x; i++ {
+		s += i
+	}
+	return &Bar{
+		x: s,
+	}
+}
+
+func newBar2(x int) (int, Itf, bool) {
+	s := 0
+	for i := 0; i < x; i++ {
+		s += i
+	}
+	return 0, &Bar{x: s}, false
+}
+
+var G int

src/cmd/compile/internal/inline/inlheur/texpr_classify_test.go

@@ -0,0 +1,222 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/internal/obj"
+	"cmd/internal/src"
+	"cmd/internal/sys"
+	"go/constant"
+	"testing"
+)
+
+var pos src.XPos
+var local *types.Pkg
+var f *ir.Func
+
+func init() {
+	types.PtrSize = 8
+	types.RegSize = 8
+	types.MaxWidth = 1 << 50
+	base.Ctxt = &obj.Link{Arch: &obj.LinkArch{Arch: &sys.Arch{Alignment: 1, CanMergeLoads: true}}}
+
+	typecheck.InitUniverse()
+	local = types.NewPkg("", "")
+	fsym := &types.Sym{
+		Pkg:  types.NewPkg("my/import/path", "path"),
+		Name: "function",
+	}
+	f = ir.NewFunc(src.NoXPos, src.NoXPos, fsym, nil)
+}
+
+type state struct {
+	ntab map[string]*ir.Name
+}
+
+func mkstate() *state {
+	return &state{
+		ntab: make(map[string]*ir.Name),
+	}
+}
+
+func bin(x ir.Node, op ir.Op, y ir.Node) ir.Node {
+	return ir.NewBinaryExpr(pos, op, x, y)
+}
+
+func conv(x ir.Node, t *types.Type) ir.Node {
+	return ir.NewConvExpr(pos, ir.OCONV, t, x)
+}
+
+func logical(x ir.Node, op ir.Op, y ir.Node) ir.Node {
+	return ir.NewLogicalExpr(pos, op, x, y)
+}
+
+func un(op ir.Op, x ir.Node) ir.Node {
+	return ir.NewUnaryExpr(pos, op, x)
+}
+
+func liti(i int64) ir.Node {
+	return ir.NewBasicLit(pos, types.Types[types.TINT64], constant.MakeInt64(i))
+}
+
+func lits(s string) ir.Node {
+	return ir.NewBasicLit(pos, types.Types[types.TSTRING], constant.MakeString(s))
+}
+
+func (s *state) nm(name string, t *types.Type) *ir.Name {
+	if n, ok := s.ntab[name]; ok {
+		if n.Type() != t {
+			panic("bad")
+		}
+		return n
+	}
+	sym := local.Lookup(name)
+	nn := ir.NewNameAt(pos, sym, t)
+	s.ntab[name] = nn
+	return nn
+}
+
+func (s *state) nmi64(name string) *ir.Name {
+	return s.nm(name, types.Types[types.TINT64])
+}
+
+func (s *state) nms(name string) *ir.Name {
+	return s.nm(name, types.Types[types.TSTRING])
+}
+
+func TestClassifyIntegerCompare(t *testing.T) {
+
+	// (n < 10 || n > 100) && (n >= 12 || n <= 99 || n != 101)
+	s := mkstate()
+	nn := s.nmi64("n")
+	nlt10 := bin(nn, ir.OLT, liti(10))         // n < 10
+	ngt100 := bin(nn, ir.OGT, liti(100))       // n > 100
+	nge12 := bin(nn, ir.OGE, liti(12))         // n >= 12
+	nle99 := bin(nn, ir.OLE, liti(99))         // n < 10
+	nne101 := bin(nn, ir.ONE, liti(101))       // n != 101
+	noror1 := logical(nlt10, ir.OOROR, ngt100) // n < 10 || n > 100
+	noror2 := logical(nge12, ir.OOROR, nle99)  // n >= 12 || n <= 99
+	noror3 := logical(noror2, ir.OOROR, nne101)
+	nandand := typecheck.Expr(logical(noror1, ir.OANDAND, noror3))
+
+	wantv := true
+	v := ShouldFoldIfNameConstant(nandand, []*ir.Name{nn})
+	if v != wantv {
+		t.Errorf("wanted shouldfold(%v) %v, got %v", nandand, wantv, v)
+	}
+}
+
+func TestClassifyStringCompare(t *testing.T) {
+
+	// s != "foo" && s < "ooblek" && s > "plarkish"
+	s := mkstate()
+	nn := s.nms("s")
+	snefoo := bin(nn, ir.ONE, lits("foo"))     // s != "foo"
+	sltoob := bin(nn, ir.OLT, lits("ooblek"))  // s < "ooblek"
+	sgtpk := bin(nn, ir.OGT, lits("plarkish")) // s > "plarkish"
+	nandand := logical(snefoo, ir.OANDAND, sltoob)
+	top := typecheck.Expr(logical(nandand, ir.OANDAND, sgtpk))
+
+	wantv := true
+	v := ShouldFoldIfNameConstant(top, []*ir.Name{nn})
+	if v != wantv {
+		t.Errorf("wanted shouldfold(%v) %v, got %v", top, wantv, v)
+	}
+}
+
+func TestClassifyIntegerArith(t *testing.T) {
+	// n+1 ^ n-3 * n/2 + n<<9 + n>>2 - n&^7
+
+	s := mkstate()
+	nn := s.nmi64("n")
+	np1 := bin(nn, ir.OADD, liti(1))     // n+1
+	nm3 := bin(nn, ir.OSUB, liti(3))     // n-3
+	nd2 := bin(nn, ir.ODIV, liti(2))     // n/2
+	nls9 := bin(nn, ir.OLSH, liti(9))    // n<<9
+	nrs2 := bin(nn, ir.ORSH, liti(2))    // n>>2
+	nan7 := bin(nn, ir.OANDNOT, liti(7)) // n&^7
+	c1xor := bin(np1, ir.OXOR, nm3)
+	c2mul := bin(c1xor, ir.OMUL, nd2)
+	c3add := bin(c2mul, ir.OADD, nls9)
+	c4add := bin(c3add, ir.OADD, nrs2)
+	c5sub := bin(c4add, ir.OSUB, nan7)
+	top := typecheck.Expr(c5sub)
+
+	wantv := true
+	v := ShouldFoldIfNameConstant(top, []*ir.Name{nn})
+	if v != wantv {
+		t.Errorf("wanted shouldfold(%v) %v, got %v", top, wantv, v)
+	}
+}
+
+func TestClassifyAssortedShifts(t *testing.T) {
+
+	s := mkstate()
+	nn := s.nmi64("n")
+	badcases := []ir.Node{
+		bin(liti(3), ir.OLSH, nn), // 3<<n
+		bin(liti(7), ir.ORSH, nn), // 7>>n
+	}
+	for _, bc := range badcases {
+		wantv := false
+		v := ShouldFoldIfNameConstant(typecheck.Expr(bc), []*ir.Name{nn})
+		if v != wantv {
+			t.Errorf("wanted shouldfold(%v) %v, got %v", bc, wantv, v)
+		}
+	}
+}
+
+func TestClassifyFloat(t *testing.T) {
+	// float32(n) + float32(10)
+	s := mkstate()
+	nn := s.nm("n", types.Types[types.TUINT32])
+	f1 := conv(nn, types.Types[types.TFLOAT32])
+	f2 := conv(liti(10), types.Types[types.TFLOAT32])
+	add := bin(f1, ir.OADD, f2)
+
+	wantv := false
+	v := ShouldFoldIfNameConstant(typecheck.Expr(add), []*ir.Name{nn})
+	if v != wantv {
+		t.Errorf("wanted shouldfold(%v) %v, got %v", add, wantv, v)
+	}
+}
+
+func TestMultipleNamesAllUsed(t *testing.T) {
+	// n != 101 && m < 2
+	s := mkstate()
+	nn := s.nmi64("n")
+	nm := s.nmi64("m")
+	nne101 := bin(nn, ir.ONE, liti(101)) // n != 101
+	mlt2 := bin(nm, ir.OLT, liti(2))     // m < 2
+	nandand := typecheck.Expr(logical(nne101, ir.OANDAND, mlt2))
+
+	// all names used
+	wantv := true
+	v := ShouldFoldIfNameConstant(nandand, []*ir.Name{nn, nm})
+	if v != wantv {
+		t.Errorf("wanted shouldfold(%v) %v, got %v", nandand, wantv, v)
+	}
+
+	// not all names used
+	wantv = false
+	v = ShouldFoldIfNameConstant(nne101, []*ir.Name{nn, nm})
+	if v != wantv {
+		t.Errorf("wanted shouldfold(%v) %v, got %v", nne101, wantv, v)
+	}
+
+	// other names used.
+	np := s.nmi64("p")
+	pne0 := bin(np, ir.ONE, liti(101)) // p != 0
+	noror := logical(nandand, ir.OOROR, pne0)
+	wantv = false
+	v = ShouldFoldIfNameConstant(noror, []*ir.Name{nn, nm})
+	if v != wantv {
+		t.Errorf("wanted shouldfold(%v) %v, got %v", noror, wantv, v)
+	}
+}

src/cmd/compile/internal/inline/inlheur/trace_off.go

@@ -0,0 +1,18 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !debugtrace
+
+package inlheur
+
+const debugTrace = 0
+
+func enableDebugTrace(x int) {
+}
+
+func enableDebugTraceIfEnv() {
+}
+
+func disableDebugTrace() {
+}

src/cmd/compile/internal/inline/inlheur/trace_on.go

@@ -0,0 +1,40 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build debugtrace
+
+package inlheur
+
+import (
+	"os"
+	"strconv"
+)
+
+var debugTrace = 0
+
+func enableDebugTrace(x int) {
+	debugTrace = x
+}
+
+func enableDebugTraceIfEnv() {
+	v := os.Getenv("DEBUG_TRACE_INLHEUR")
+	if v == "" {
+		return
+	}
+	if v[0] == '*' {
+		if !UnitTesting() {
+			return
+		}
+		v = v[1:]
+	}
+	i, err := strconv.Atoi(v)
+	if err != nil {
+		return
+	}
+	debugTrace = i
+}
+
+func disableDebugTrace() {
+	debugTrace = 0
+}

src/cmd/compile/internal/inline/inlheur/tserial_test.go

@@ -0,0 +1,65 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package inlheur
+
+import "testing"
+
+func fpeq(fp1, fp2 FuncProps) bool {
+	if fp1.Flags != fp2.Flags {
+		return false
+	}
+	if len(fp1.ParamFlags) != len(fp2.ParamFlags) {
+		return false
+	}
+	for i := range fp1.ParamFlags {
+		if fp1.ParamFlags[i] != fp2.ParamFlags[i] {
+			return false
+		}
+	}
+	if len(fp1.ResultFlags) != len(fp2.ResultFlags) {
+		return false
+	}
+	for i := range fp1.ResultFlags {
+		if fp1.ResultFlags[i] != fp2.ResultFlags[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func TestSerDeser(t *testing.T) {
+	testcases := []FuncProps{
+		FuncProps{},
+		FuncProps{
+			Flags: 0xfffff,
+		},
+		FuncProps{
+			Flags:       1,
+			ResultFlags: []ResultPropBits{ResultAlwaysSameConstant},
+		},
+		FuncProps{
+			Flags:       1,
+			ParamFlags:  []ParamPropBits{0x99, 0xaa, 0xfffff},
+			ResultFlags: []ResultPropBits{0xfeedface},
+		},
+	}
+
+	for k, tc := range testcases {
+		s := tc.SerializeToString()
+		fp := DeserializeFromString(s)
+		got := fp.String()
+		want := tc.String()
+		if !fpeq(*fp, tc) {
+			t.Errorf("eq check failed for test %d: got:\n%s\nwant:\n%s\n", k, got, want)
+		}
+	}
+
+	var nilt *FuncProps
+	ns := nilt.SerializeToString()
+	nfp := DeserializeFromString(ns)
+	if len(ns) != 0 || nfp != nil {
+		t.Errorf("nil serialize/deserialize failed")
+	}
+}