cl: support go:linkname

cl/_testdata/apkg/in.go

@@ -0,0 +1,8 @@
+package apkg
+
+func Max(a, b float64) float64 {
+	if a > b {
+		return a
+	}
+	return b
+}

cl/_testdata/apkg/out.ll

@@ -0,0 +1,29 @@
+; ModuleID = 'apkg'
+source_filename = "apkg"
+
+@"init$guard" = global ptr null
+
+define void @apkg.init() {
+_llgo_0:
+  %0 = load i1, ptr @"init$guard", align 1
+  br i1 %0, label %_llgo_2, label %_llgo_1
+
+_llgo_1:                                          ; preds = %_llgo_0
+  store i1 true, ptr @"init$guard", align 1
+  br label %_llgo_2
+
+_llgo_2:                                          ; preds = %_llgo_1, %_llgo_0
+  ret void
+}
+
+define double @apkg.Max(double %0, double %1) {
+_llgo_0:
+  %2 = fcmp ogt double %0, %1
+  br i1 %2, label %_llgo_1, label %_llgo_2
+
+_llgo_1:                                          ; preds = %_llgo_0
+  ret double %0
+
+_llgo_2:                                          ; preds = %_llgo_0
+  ret double %1
+}

cl/_testdata/fncall/out.ll

@@ -3,7 +3,7 @@ source_filename = "main"
 
 @"init$guard" = global ptr null
 
-define void @init() {
+define void @main.init() {
 _llgo_0:
   %0 = load i1, ptr @"init$guard", align 1
   br i1 %0, label %_llgo_2, label %_llgo_1
@@ -16,7 +16,7 @@ _llgo_2:                                          ; preds = %_llgo_1, %_llgo_0
   ret void
 }
 
-define i64 @max(i64 %0, i64 %1) {
+define i64 @main.max(i64 %0, i64 %1) {
 _llgo_0:
   %2 = icmp sgt i64 %0, %1
   br i1 %2, label %_llgo_1, label %_llgo_2
@@ -30,7 +30,7 @@ _llgo_2:                                          ; preds = %_llgo_0
 
 define void @main() {
 _llgo_0:
-  call void @init()
-  %0 = call i64 @max(i64 1, i64 2)
+  call void @main.init()
+  %0 = call i64 @main.max(i64 1, i64 2)
   ret void
 }

cl/_testdata/printf/in.go

@@ -2,7 +2,7 @@ package main
 
 import _ "unsafe"
 
-//go:linkname printf _printf
+//go:linkname printf printf
 func printf(format *int8, __llgo_va_list ...any)
 
 var hello = [...]int8{'H', 'e', 'l', 'l', 'o', '\n', 0}

cl/_testdata/printf/out.ll

@@ -4,7 +4,7 @@ source_filename = "main"
 @"init$guard" = global ptr null
 @hello = global ptr null
 
-define void @init() {
+define void @main.init() {
 _llgo_0:
   %0 = load i1, ptr @"init$guard", align 1
   br i1 %0, label %_llgo_2, label %_llgo_1
@@ -28,7 +28,7 @@ declare void @printf(ptr, ...)
 
 define void @main() {
 _llgo_0:
-  call void @init()
+  call void @main.init()
   call void (ptr, ...) @printf(ptr @hello)
   ret void
 }

cl/_testdata/varinit/out.ll

@@ -4,7 +4,7 @@ source_filename = "main"
 @"init$guard" = global ptr null
 @a = global ptr null
 
-define void @init() {
+define void @main.init() {
 _llgo_0:
   %0 = load i1, ptr @"init$guard", align 1
   br i1 %0, label %_llgo_2, label %_llgo_1
@@ -20,7 +20,7 @@ _llgo_2:                                          ; preds = %_llgo_1, %_llgo_0
 
 define void @main() {
 _llgo_0:
-  call void @init()
+  call void @main.init()
   %0 = load i64, ptr @a, align 4
   %1 = add i64 %0, 1
   store i64 %1, ptr @a, align 4

cl/compile.go

@@ -18,9 +18,11 @@ package cl
 
 import (
 	"fmt"
+	"go/ast"
 	"log"
 	"os"
 	"sort"
+	"strings"
 
 	llssa "github.com/goplus/llgo/ssa"
 	"golang.org/x/tools/go/ssa"
@@ -73,8 +75,12 @@ func funcKind(vfn ssa.Value) int {
 	return fnNormal
 }
 
-func isMainFunc(fn *ssa.Function) bool {
-	return fn.Name() == "main" && fn.Pkg.Pkg.Path() == "main"
+func funcName(fn *ssa.Function) string {
+	ret := fn.Pkg.Pkg.Path() + "." + fn.Name()
+	if ret == "main.main" {
+		ret = "main"
+	}
+	return ret
 }
 
 // -----------------------------------------------------------------------------
@@ -89,10 +95,46 @@ type context struct {
 	pkg   llssa.Package
 	fn    llssa.Function
 	goPkg *ssa.Package
+	link  map[string]string
 	bvals map[ssa.Value]llssa.Expr // block values
 	inits []func()
 }
 
+func (p *context) initFiles(pkgPath string, files []*ast.File) {
+	for _, file := range files {
+		for _, decl := range file.Decls {
+			if decl, ok := decl.(*ast.FuncDecl); ok {
+				if decl.Recv == nil && decl.Doc != nil {
+					p.initLinkname(pkgPath, decl.Doc)
+				}
+			}
+		}
+	}
+}
+
+func (p *context) initLinkname(pkgPath string, doc *ast.CommentGroup) {
+	const (
+		linkname = "//go:linkname "
+	)
+	for _, c := range doc.List {
+		if strings.HasPrefix(c.Text, linkname) {
+			text := strings.TrimSpace(c.Text[len(linkname):])
+			if idx := strings.IndexByte(text, ' '); idx > 0 {
+				name := pkgPath + "." + text[:idx]
+				p.link[name] = strings.TrimLeft(text[idx+1:], " ")
+			}
+		}
+	}
+}
+
+func (p *context) funcName(fn *ssa.Function) string {
+	name := funcName(fn)
+	if v, ok := p.link[name]; ok {
+		return v
+	}
+	return name
+}
+
 func (p *context) compileType(pkg llssa.Package, member *ssa.Type) {
 	panic("todo")
 }
@@ -108,7 +150,7 @@ func (p *context) compileGlobal(pkg llssa.Package, gbl *ssa.Global) {
 }
 
 func (p *context) compileFunc(pkg llssa.Package, f *ssa.Function) {
-	name := f.Name()
+	name := p.funcName(f)
 	if debugInstr {
 		log.Println("==> NewFunc", name)
 	}
@@ -130,9 +172,8 @@ func (p *context) compileFunc(pkg llssa.Package, f *ssa.Function) {
 		}
 		fn.MakeBlocks(nblk)
 		b := fn.NewBuilder()
-		isMain := isMainFunc(f)
 		for i, block := range f.Blocks {
-			p.compileBlock(b, block, isMain && i == 0)
+			p.compileBlock(b, block, i == 0 && name == "main")
 		}
 	})
 }
@@ -142,7 +183,7 @@ func (p *context) compileBlock(b llssa.Builder, block *ssa.BasicBlock, doInit bo
 	b.SetBlock(ret)
 	p.bvals = make(map[ssa.Value]llssa.Expr)
 	if doInit {
-		fn := p.pkg.FuncOf("init")
+		fn := p.pkg.FuncOf("main.init")
 		b.Call(fn.Expr)
 	}
 	for _, instr := range block.Instrs {
@@ -241,7 +282,7 @@ func (p *context) compileValue(b llssa.Builder, v ssa.Value) llssa.Expr {
 		if v.Pkg != p.goPkg {
 			panic("todo")
 		}
-		fn := p.pkg.FuncOf(v.Name())
+		fn := p.pkg.FuncOf(p.funcName(v))
 		return fn.Expr
 	case *ssa.Global:
 		if v.Pkg != p.goPkg {
@@ -281,16 +322,20 @@ func (p *context) compileValues(b llssa.Builder, vals []ssa.Value, hasVArg int)
 
 // -----------------------------------------------------------------------------
 
-type Config struct {
+type GoPackage struct {
+	SSA   *ssa.Package
+	Files []*ast.File
 }
 
 // NewPackage compiles a Go package to LLVM IR package.
-func NewPackage(prog llssa.Program, pkg *ssa.Package, conf *Config) (ret llssa.Package, err error) {
+func NewPackage(prog llssa.Program, in *GoPackage) (ret llssa.Package, err error) {
 	type namedMember struct {
 		name string
 		val  ssa.Member
 	}
 
+	pkg := in.SSA
+
 	// Sort by position, so that the order of the functions in the IR matches
 	// the order of functions in the source file. This is useful for testing,
 	// for example.
@@ -311,7 +356,9 @@ func NewPackage(prog llssa.Program, pkg *ssa.Package, conf *Config) (ret llssa.P
 		prog:  prog,
 		pkg:   ret,
 		goPkg: pkg,
+		link:  make(map[string]string),
 	}
+	ctx.initFiles(pkgTypes.Path(), in.Files)
 	for _, m := range members {
 		member := m.val
 		switch member := member.(type) {

cl/compile_test.go

@@ -95,7 +95,7 @@ func testCompileEx(t *testing.T, src any, fname, expected string) {
 	}
 	foo.WriteTo(os.Stderr)
 	prog := llssa.NewProgram(nil)
-	ret, err := NewPackage(prog, foo, nil)
+	ret, err := NewPackage(prog, &GoPackage{SSA: foo, Files: files})
 	if err != nil {
 		t.Fatal("cl.NewPackage failed:", err)
 	}
@@ -119,7 +119,7 @@ source_filename = "foo"
 @"init$guard" = global ptr null
 @a = global ptr null
 
-define void @init() {
+define void @foo.init() {
 _llgo_0:
   %0 = load i1, ptr @"init$guard", align 1
   br i1 %0, label %_llgo_2, label %_llgo_1
@@ -145,7 +145,7 @@ source_filename = "foo"
 
 @"init$guard" = global ptr null
 
-define void @init() {
+define void @foo.init() {
 _llgo_0:
   %0 = load i1, ptr @"init$guard", align 1
   br i1 %0, label %_llgo_2, label %_llgo_1
@@ -158,7 +158,7 @@ _llgo_2:                                          ; preds = %_llgo_1, %_llgo_0
   ret void
 }
 
-define i64 @fn(i64 %0, double %1) {
+define i64 @foo.fn(i64 %0, double %1) {
 _llgo_0:
   ret i64 1
 }

cl/internal/stdio/printf.go

@@ -0,0 +1,6 @@
+package stdio
+
+import _ "unsafe"
+
+//go:linkname printf printf
+func printf(format *int8, __llgo_va_list ...any)

internal/llgen/llgen.go

@@ -58,7 +58,7 @@ func Gen(inFile string, src any) string {
 	ssaPkg.WriteTo(os.Stderr)
 
 	prog := llssa.NewProgram(nil)
-	ret, err := cl.NewPackage(prog, ssaPkg, nil)
+	ret, err := cl.NewPackage(prog, &cl.GoPackage{SSA: ssaPkg, Files: files})
 	check(err)
 
 	return ret.String()

ssa/expr.go

@@ -230,7 +230,7 @@ func (b Builder) BinOp(op token.Token, x, y Expr) Expr {
 			return Expr{llvm.CreateICmp(b.impl, pred, x.impl, y.impl), tret}
 		case vkFloat:
 			pred := floatPredOpToLLVM[op-predOpBase]
-			return Expr{llvm.ConstFCmp(pred, x.impl, y.impl), tret}
+			return Expr{llvm.CreateFCmp(b.impl, pred, x.impl, y.impl), tret}
 		case vkString, vkComplex, vkBool:
 			panic("todo")
 		}