Merge pull request #1348 from cpunion/feature/defer-loop

defer: enable loop lowering
2025-11-13 17:59:26 +08:00
parent 3f8c95cf87 aeb5d82d3e
commit 2f65c98eb4
26 changed files with 745 additions and 5695 deletions
--- a/README.md
+++ b/README.md
@@ -261,7 +261,7 @@ All Go syntax (including `cgo`) is already supported. Here are some examples:

 ### Defer

-LLGo `defer` does not support usage in loops. This is not a bug but a feature, because we think that using `defer` in a loop is a very unrecommended practice.
+LLGo now supports `defer` within loops, matching Go's semantics of executing defers in LIFO order for every iteration. The usual caveat from Go still applies: be mindful of loop-heavy defer usage because it allocates per iteration.


 ### Garbage Collection (GC)
--- a/_demo/go/export/libexport.h.want
+++ b/_demo/go/export/libexport.h.want
@@ -300,6 +300,9 @@ github_com_goplus_llgo_runtime_internal_clite_pthread_sync_init(void) GO_SYMBOL_
 void
 github_com_goplus_llgo_runtime_internal_clite_signal_init(void) GO_SYMBOL_RENAME("github.com/goplus/llgo/runtime/internal/clite/signal.init")

+void
+github_com_goplus_llgo_runtime_internal_clite_tls_init(void) GO_SYMBOL_RENAME("github.com/goplus/llgo/runtime/internal/clite/tls.init")
+
 void
 github_com_goplus_llgo_runtime_internal_runtime_goarch_init(void) GO_SYMBOL_RENAME("github.com/goplus/llgo/runtime/internal/runtime/goarch.init")

--- a/cl/_testgo/defercomplex/in.go
+++ b/cl/_testgo/defercomplex/in.go
@@ -0,0 +1,51 @@
+package main
+
+func main() {
+	for _, label := range complexOrder() {
+		println(label)
+	}
+}
+
+func complexOrder() (res []string) {
+	record := func(label string) { res = append(res, label) }
+
+	defer record(label1("cleanup-final", 0))
+	defer record(label1("cleanup-before-loop", 0))
+
+	for i := 0; i < 2; i++ {
+		defer record(label1("exit-outer", i))
+		for j := 0; j < 2; j++ {
+			if j == 0 {
+				defer record(label2("branch-even", i, j))
+			} else {
+				defer record(label2("branch-odd", i, j))
+			}
+			for k := 0; k < 2; k++ {
+				nested := label3("nested", i, j, k)
+				defer record(nested)
+				if k == 1 {
+					defer record(label3("nested-tail", i, j, k))
+				}
+			}
+		}
+	}
+
+	defer record(label1("post-loop", 0))
+	return
+}
+
+func label1(prefix string, a int) string {
+	return prefix + "-" + digit(a)
+}
+
+func label2(prefix string, a, b int) string {
+	return prefix + "-" + digit(a) + "-" + digit(b)
+}
+
+func label3(prefix string, a, b, c int) string {
+	return prefix + "-" + digit(a) + "-" + digit(b) + "-" + digit(c)
+}
+
+func digit(n int) string {
+	return string(rune('0' + n))
+}
--- a/cl/_testgo/defercomplex/out.ll
+++ b/cl/_testgo/defercomplex/out.ll
@@ -0,0 +1 @@
+;
--- a/cl/_testgo/deferloop/in.go
+++ b/cl/_testgo/deferloop/in.go
@@ -0,0 +1,7 @@
+package main
+
+func main() {
+	for i := 0; i < 3; i++ {
+		defer println("loop", i)
+	}
+}
--- a/cl/_testgo/deferloop/out.ll
+++ b/cl/_testgo/deferloop/out.ll
@@ -0,0 +1 @@
+;
--- a/cl/compile.go
+++ b/cl/compile.go
@@ -110,6 +110,7 @@ type context struct {
 	loaded      map[*types.Package]*pkgInfo // loaded packages
 	bvals       map[ssa.Value]llssa.Expr    // block values
 	vargs       map[*ssa.Alloc][]llssa.Expr // varargs
+	paramDIVars map[*types.Var]llssa.DIVar

 	patches  Patches
 	blkInfos []blocks.Info
@@ -263,6 +264,8 @@ func (p *context) compileFuncDecl(pkg llssa.Package, f *ssa.Function) (llssa.Fun
 		if f.Recover != nil { // set recover block
 			fn.SetRecover(fn.Block(f.Recover.Index))
 		}
+		dbgEnabled := enableDbg && (f == nil || f.Origin() == nil)
+		dbgSymsEnabled := enableDbgSyms && (f == nil || f.Origin() == nil)
 		p.inits = append(p.inits, func() {
 			p.fn = fn
 			p.state = state // restore pkgState when compiling funcBody
@@ -270,6 +273,11 @@ func (p *context) compileFuncDecl(pkg llssa.Package, f *ssa.Function) (llssa.Fun
 				p.fn = nil
 			}()
 			p.phis = nil
+			if dbgSymsEnabled {
+				p.paramDIVars = make(map[*types.Var]llssa.DIVar)
+			} else {
+				p.paramDIVars = nil
+			}
 			if debugGoSSA {
 				f.WriteTo(os.Stderr)
 			}
@@ -277,7 +285,7 @@ func (p *context) compileFuncDecl(pkg llssa.Package, f *ssa.Function) (llssa.Fun
 				log.Println("==> FuncBody", name)
 			}
 			b := fn.NewBuilder()
-			if enableDbg {
+			if dbgEnabled {
 				pos := p.goProg.Fset.Position(f.Pos())
 				bodyPos := p.getFuncBodyPos(f)
 				b.DebugFunction(fn, pos, bodyPos)
@@ -371,6 +379,9 @@ func (p *context) debugParams(b llssa.Builder, f *ssa.Function) {
 		ty := param.Type()
 		argNo := i + 1
 		div := b.DIVarParam(p.fn, pos, param.Name(), p.type_(ty, llssa.InGo), argNo)
+		if p.paramDIVars != nil {
+			p.paramDIVars[variable] = div
+		}
 		b.DIParam(variable, v, div, p.fn, pos, p.fn.Block(0))
 	}
 }
@@ -388,7 +399,7 @@ func (p *context) compileBlock(b llssa.Builder, block *ssa.BasicBlock, n int, do
 		b.Printf("call " + fn.Name() + "\n\x00")
 	}
 	// place here to avoid wrong current-block
-	if enableDbgSyms && block.Index == 0 {
+	if enableDbgSyms && block.Parent().Origin() == nil && block.Index == 0 {
 		p.debugParams(b, block.Parent())
 	}
 	if doModInit {
@@ -783,7 +794,7 @@ func (p *context) compileInstr(b llssa.Builder, instr ssa.Instruction) {
 		p.compileInstrOrValue(b, iv, false)
 		return
 	}
-	if enableDbg {
+	if enableDbg && instr.Parent().Origin() == nil {
 		scope := p.getDebugLocScope(instr.Parent(), instr.Pos())
 		if scope != nil {
 			diScope := b.DIScope(p.fn, scope)
@@ -846,7 +857,7 @@ func (p *context) compileInstr(b llssa.Builder, instr ssa.Instruction) {
 		x := p.compileValue(b, v.X)
 		b.Send(ch, x)
 	case *ssa.DebugRef:
-		if enableDbgSyms {
+		if enableDbgSyms && v.Parent().Origin() == nil {
 			p.debugRef(b, v)
 		}
 	default:
@@ -855,14 +866,13 @@ func (p *context) compileInstr(b llssa.Builder, instr ssa.Instruction) {
 }

 func (p *context) getLocalVariable(b llssa.Builder, fn *ssa.Function, v *types.Var) llssa.DIVar {
+	if p.paramDIVars != nil {
+		if div, ok := p.paramDIVars[v]; ok {
+			return div
+		}
+	}
 	pos := p.fset.Position(v.Pos())
 	t := p.type_(v.Type(), llssa.InGo)
-	for i, param := range fn.Params {
-		if param.Object().(*types.Var) == v {
-			argNo := i + 1
-			return b.DIVarParam(p.fn, pos, v.Name(), t, argNo)
-		}
-	}
 	scope := b.DIScope(p.fn, v.Parent())
 	return b.DIVarAuto(scope, pos, v.Name(), t)
 }
--- a/doc/defer-tls-gc.md
+++ b/doc/defer-tls-gc.md
@@ -0,0 +1,32 @@
+# Defer Loop GC Integration
+
+## Background
+
+`defer` chains are stored in a per-thread TLS slot so that unwind paths can locate the active `*runtime.Defer`. With the default allocator (`AllocU`) backed by Boehm GC (bdwgc), those TLS-resident pointers were invisible to the collector. In stress scenarios—e.g. `TestDeferLoopStress` with 1,000,000 defers—the collector reclaimed the defer nodes, leaving dangling pointers and causing crashes inside the deferred closures.
+
+Prior experiments (`test-defer-dont-free` branch) confirmed the crash disappeared when allocations bypassed GC (plain `malloc` without `free`), pointing to a root-registration gap rather than logical corruption.
+
+## Solution Overview
+
+1. **GC-aware TLS slot helper** *(from PR [#1347](https://github.com/goplus/llgo/pull/1347))*
+   - Added `runtime/internal/clite/tls`, which exposes `tls.Alloc` to create per-thread storage that is automatically registered as a Boehm GC root.
+   - `SetThreadDefer` delegates to this helper so every thread reuses the same GC-safe slot without bespoke plumbing.
+   - The package handles TLS key creation, root registration/removal, and invokes an optional destructor when a thread exits.
+
+2. **SSA codegen synchronization**
+   - `ssa/eh.go` now calls `runtime.SetThreadDefer` whenever it updates the TLS pointer (on first allocation and when restoring the previous link during unwind).
+   - Defer argument nodes and the `runtime.Defer` struct itself are allocated with `aggregateAllocU`, ensuring new memory comes from GC-managed heaps, and nodes are released via `runtime.FreeDeferNode`.
+
+3. **Non-GC builds**
+   - The `tls` helper falls back to a malloc-backed TLS slot without GC registration, while `FreeDeferNode` continues to release nodes via `c.Free` when building with `-tags nogc`.
+
+## Testing
+
+Run the stress and regression suites to validate the integration:
+
+```sh
+./llgo.sh test ./test -run TestDeferLoopStress
+./llgo.sh test ./test
+```
+
+The updated `TestDeferLoopStress` now asserts 1,000,000 loop defers execute without failure, catching regressions in GC root tracking.
--- a/internal/crosscompile/compile/libc/libc_test.go
+++ b/internal/crosscompile/compile/libc/libc_test.go
@@ -1,3 +1,5 @@
+//go:build !llgo
+
 package libc

 import (
--- a/runtime/_overlay/go/parser/resolver.go
+++ b/runtime/_overlay/go/parser/resolver.go
@@ -1,622 +0,0 @@
-// Copyright 2021 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 parser
-
-import (
-	"fmt"
-	"go/ast"
-	"go/token"
-	"strings"
-)
-
-const debugResolve = false
-
-// resolveFile walks the given file to resolve identifiers within the file
-// scope, updating ast.Ident.Obj fields with declaration information.
-//
-// If declErr is non-nil, it is used to report declaration errors during
-// resolution. tok is used to format position in error messages.
-func resolveFile(file *ast.File, handle *token.File, declErr func(token.Pos, string)) {
-	pkgScope := ast.NewScope(nil)
-	r := &resolver{
-		handle:   handle,
-		declErr:  declErr,
-		topScope: pkgScope,
-		pkgScope: pkgScope,
-		depth:    1,
-	}
-
-	for _, decl := range file.Decls {
-		ast.Walk(r, decl)
-	}
-
-	r.closeScope()
-	assert(r.topScope == nil, "unbalanced scopes")
-	assert(r.labelScope == nil, "unbalanced label scopes")
-
-	// resolve global identifiers within the same file
-	i := 0
-	for _, ident := range r.unresolved {
-		// i <= index for current ident
-		assert(ident.Obj == unresolved, "object already resolved")
-		ident.Obj = r.pkgScope.Lookup(ident.Name) // also removes unresolved sentinel
-		if ident.Obj == nil {
-			r.unresolved[i] = ident
-			i++
-		} else if debugResolve {
-			pos := ident.Obj.Decl.(interface{ Pos() token.Pos }).Pos()
-			r.trace("resolved %s@%v to package object %v", ident.Name, ident.Pos(), pos)
-		}
-	}
-	file.Scope = r.pkgScope
-	file.Unresolved = r.unresolved[0:i]
-}
-
-const maxScopeDepth int = 1e3
-
-type resolver struct {
-	handle  *token.File
-	declErr func(token.Pos, string)
-
-	// Ordinary identifier scopes
-	pkgScope   *ast.Scope   // pkgScope.Outer == nil
-	topScope   *ast.Scope   // top-most scope; may be pkgScope
-	unresolved []*ast.Ident // unresolved identifiers
-	depth      int          // scope depth
-
-	// Label scopes
-	// (maintained by open/close LabelScope)
-	labelScope  *ast.Scope     // label scope for current function
-	targetStack [][]*ast.Ident // stack of unresolved labels
-}
-
-func (r *resolver) trace(format string, args ...any) {
-	fmt.Println(strings.Repeat(". ", r.depth) + r.sprintf(format, args...))
-}
-
-func (r *resolver) sprintf(format string, args ...any) string {
-	for i, arg := range args {
-		switch arg := arg.(type) {
-		case token.Pos:
-			args[i] = r.handle.Position(arg)
-		}
-	}
-	return fmt.Sprintf(format, args...)
-}
-
-func (r *resolver) openScope(pos token.Pos) {
-	r.depth++
-	if r.depth > maxScopeDepth {
-		panic(bailout{pos: pos, msg: "exceeded max scope depth during object resolution"})
-	}
-	if debugResolve {
-		r.trace("opening scope @%v", pos)
-	}
-	r.topScope = ast.NewScope(r.topScope)
-}
-
-func (r *resolver) closeScope() {
-	r.depth--
-	if debugResolve {
-		r.trace("closing scope")
-	}
-	r.topScope = r.topScope.Outer
-}
-
-func (r *resolver) openLabelScope() {
-	r.labelScope = ast.NewScope(r.labelScope)
-	r.targetStack = append(r.targetStack, nil)
-}
-
-func (r *resolver) closeLabelScope() {
-	// resolve labels
-	n := len(r.targetStack) - 1
-	scope := r.labelScope
-	for _, ident := range r.targetStack[n] {
-		ident.Obj = scope.Lookup(ident.Name)
-		if ident.Obj == nil && r.declErr != nil {
-			r.declErr(ident.Pos(), fmt.Sprintf("label %s undefined", ident.Name))
-		}
-	}
-	// pop label scope
-	r.targetStack = r.targetStack[0:n]
-	r.labelScope = r.labelScope.Outer
-}
-
-func (r *resolver) declare(decl, data any, scope *ast.Scope, kind ast.ObjKind, idents ...*ast.Ident) {
-	for _, ident := range idents {
-		if ident.Obj != nil {
-			panic(fmt.Sprintf("%v: identifier %s already declared or resolved", ident.Pos(), ident.Name))
-		}
-		obj := ast.NewObj(kind, ident.Name)
-		// remember the corresponding declaration for redeclaration
-		// errors and global variable resolution/typechecking phase
-		obj.Decl = decl
-		obj.Data = data
-		// Identifiers (for receiver type parameters) are written to the scope, but
-		// never set as the resolved object. See go.dev/issue/50956.
-		if _, ok := decl.(*ast.Ident); !ok {
-			ident.Obj = obj
-		}
-		if ident.Name != "_" {
-			if debugResolve {
-				r.trace("declaring %s@%v", ident.Name, ident.Pos())
-			}
-			if alt := scope.Insert(obj); alt != nil && r.declErr != nil {
-				prevDecl := ""
-				if pos := alt.Pos(); pos.IsValid() {
-					prevDecl = r.sprintf("\n\tprevious declaration at %v", pos)
-				}
-				r.declErr(ident.Pos(), fmt.Sprintf("%s redeclared in this block%s", ident.Name, prevDecl))
-			}
-		}
-	}
-}
-
-func (r *resolver) shortVarDecl(decl *ast.AssignStmt) {
-	// Go spec: A short variable declaration may redeclare variables
-	// provided they were originally declared in the same block with
-	// the same type, and at least one of the non-blank variables is new.
-	n := 0 // number of new variables
-	for _, x := range decl.Lhs {
-		if ident, isIdent := x.(*ast.Ident); isIdent {
-			assert(ident.Obj == nil, "identifier already declared or resolved")
-			obj := ast.NewObj(ast.Var, ident.Name)
-			// remember corresponding assignment for other tools
-			obj.Decl = decl
-			ident.Obj = obj
-			if ident.Name != "_" {
-				if debugResolve {
-					r.trace("declaring %s@%v", ident.Name, ident.Pos())
-				}
-				if alt := r.topScope.Insert(obj); alt != nil {
-					ident.Obj = alt // redeclaration
-				} else {
-					n++ // new declaration
-				}
-			}
-		}
-	}
-	if n == 0 && r.declErr != nil {
-		r.declErr(decl.Lhs[0].Pos(), "no new variables on left side of :=")
-	}
-}
-
-// The unresolved object is a sentinel to mark identifiers that have been added
-// to the list of unresolved identifiers. The sentinel is only used for verifying
-// internal consistency.
-var unresolved = new(ast.Object)
-
-// If x is an identifier, resolve attempts to resolve x by looking up
-// the object it denotes. If no object is found and collectUnresolved is
-// set, x is marked as unresolved and collected in the list of unresolved
-// identifiers.
-func (r *resolver) resolve(ident *ast.Ident, collectUnresolved bool) {
-	if ident.Obj != nil {
-		panic(r.sprintf("%v: identifier %s already declared or resolved", ident.Pos(), ident.Name))
-	}
-	// '_' should never refer to existing declarations, because it has special
-	// handling in the spec.
-	if ident.Name == "_" {
-		return
-	}
-	for s := r.topScope; s != nil; s = s.Outer {
-		if obj := s.Lookup(ident.Name); obj != nil {
-			if debugResolve {
-				r.trace("resolved %v:%s to %v", ident.Pos(), ident.Name, obj)
-			}
-			assert(obj.Name != "", "obj with no name")
-			// Identifiers (for receiver type parameters) are written to the scope,
-			// but never set as the resolved object. See go.dev/issue/50956.
-			if _, ok := obj.Decl.(*ast.Ident); !ok {
-				ident.Obj = obj
-			}
-			return
-		}
-	}
-	// all local scopes are known, so any unresolved identifier
-	// must be found either in the file scope, package scope
-	// (perhaps in another file), or universe scope --- collect
-	// them so that they can be resolved later
-	if collectUnresolved {
-		ident.Obj = unresolved
-		r.unresolved = append(r.unresolved, ident)
-	}
-}
-
-func (r *resolver) walkExprs(list []ast.Expr) {
-	for _, node := range list {
-		ast.Walk(r, node)
-	}
-}
-
-func Unparen(e ast.Expr) ast.Expr {
-	for {
-		paren, ok := e.(*ast.ParenExpr)
-		if !ok {
-			return e
-		}
-		e = paren.X
-	}
-}
-
-func (r *resolver) walkLHS(list []ast.Expr) {
-	for _, expr := range list {
-		expr := Unparen(expr)
-		if _, ok := expr.(*ast.Ident); !ok && expr != nil {
-			ast.Walk(r, expr)
-		}
-	}
-}
-
-func (r *resolver) walkStmts(list []ast.Stmt) {
-	for _, stmt := range list {
-		ast.Walk(r, stmt)
-	}
-}
-
-func (r *resolver) Visit(node ast.Node) ast.Visitor {
-	if debugResolve && node != nil {
-		r.trace("node %T@%v", node, node.Pos())
-	}
-
-	switch n := node.(type) {
-
-	// Expressions.
-	case *ast.Ident:
-		r.resolve(n, true)
-
-	case *ast.FuncLit:
-		r.openScope(n.Pos())
-		defer r.closeScope()
-		r.walkFuncType(n.Type)
-		r.walkBody(n.Body)
-
-	case *ast.SelectorExpr:
-		ast.Walk(r, n.X)
-		// Note: don't try to resolve n.Sel, as we don't support qualified
-		// resolution.
-
-	case *ast.StructType:
-		r.openScope(n.Pos())
-		defer r.closeScope()
-		r.walkFieldList(n.Fields, ast.Var)
-
-	case *ast.FuncType:
-		r.openScope(n.Pos())
-		defer r.closeScope()
-		r.walkFuncType(n)
-
-	case *ast.CompositeLit:
-		if n.Type != nil {
-			ast.Walk(r, n.Type)
-		}
-		for _, e := range n.Elts {
-			if kv, _ := e.(*ast.KeyValueExpr); kv != nil {
-				// See go.dev/issue/45160: try to resolve composite lit keys, but don't
-				// collect them as unresolved if resolution failed. This replicates
-				// existing behavior when resolving during parsing.
-				if ident, _ := kv.Key.(*ast.Ident); ident != nil {
-					r.resolve(ident, false)
-				} else {
-					ast.Walk(r, kv.Key)
-				}
-				ast.Walk(r, kv.Value)
-			} else {
-				ast.Walk(r, e)
-			}
-		}
-
-	case *ast.InterfaceType:
-		r.openScope(n.Pos())
-		defer r.closeScope()
-		r.walkFieldList(n.Methods, ast.Fun)
-
-	// Statements
-	case *ast.LabeledStmt:
-		r.declare(n, nil, r.labelScope, ast.Lbl, n.Label)
-		ast.Walk(r, n.Stmt)
-
-	case *ast.AssignStmt:
-		r.walkExprs(n.Rhs)
-		if n.Tok == token.DEFINE {
-			r.shortVarDecl(n)
-		} else {
-			r.walkExprs(n.Lhs)
-		}
-
-	case *ast.BranchStmt:
-		// add to list of unresolved targets
-		if n.Tok != token.FALLTHROUGH && n.Label != nil {
-			depth := len(r.targetStack) - 1
-			r.targetStack[depth] = append(r.targetStack[depth], n.Label)
-		}
-
-	case *ast.BlockStmt:
-		r.openScope(n.Pos())
-		defer r.closeScope()
-		r.walkStmts(n.List)
-
-	case *ast.IfStmt:
-		r.openScope(n.Pos())
-		defer r.closeScope()
-		if n.Init != nil {
-			ast.Walk(r, n.Init)
-		}
-		ast.Walk(r, n.Cond)
-		ast.Walk(r, n.Body)
-		if n.Else != nil {
-			ast.Walk(r, n.Else)
-		}
-
-	case *ast.CaseClause:
-		r.walkExprs(n.List)
-		r.openScope(n.Pos())
-		defer r.closeScope()
-		r.walkStmts(n.Body)
-
-	case *ast.SwitchStmt:
-		r.openScope(n.Pos())
-		defer r.closeScope()
-		if n.Init != nil {
-			ast.Walk(r, n.Init)
-		}
-		if n.Tag != nil {
-			// The scope below reproduces some unnecessary behavior of the parser,
-			// opening an extra scope in case this is a type switch. It's not needed
-			// for expression switches.
-			// TODO: remove this once we've matched the parser resolution exactly.
-			if n.Init != nil {
-				r.openScope(n.Tag.Pos())
-				defer r.closeScope()
-			}
-			ast.Walk(r, n.Tag)
-		}
-		if n.Body != nil {
-			r.walkStmts(n.Body.List)
-		}
-
-	case *ast.TypeSwitchStmt:
-		if n.Init != nil {
-			r.openScope(n.Pos())
-			defer r.closeScope()
-			ast.Walk(r, n.Init)
-		}
-		r.openScope(n.Assign.Pos())
-		defer r.closeScope()
-		ast.Walk(r, n.Assign)
-		// s.Body consists only of case clauses, so does not get its own
-		// scope.
-		if n.Body != nil {
-			r.walkStmts(n.Body.List)
-		}
-
-	case *ast.CommClause:
-		r.openScope(n.Pos())
-		defer r.closeScope()
-		if n.Comm != nil {
-			ast.Walk(r, n.Comm)
-		}
-		r.walkStmts(n.Body)
-
-	case *ast.SelectStmt:
-		// as for switch statements, select statement bodies don't get their own
-		// scope.
-		if n.Body != nil {
-			r.walkStmts(n.Body.List)
-		}
-
-	case *ast.ForStmt:
-		r.openScope(n.Pos())
-		defer r.closeScope()
-		if n.Init != nil {
-			ast.Walk(r, n.Init)
-		}
-		if n.Cond != nil {
-			ast.Walk(r, n.Cond)
-		}
-		if n.Post != nil {
-			ast.Walk(r, n.Post)
-		}
-		ast.Walk(r, n.Body)
-
-	case *ast.RangeStmt:
-		r.openScope(n.Pos())
-		defer r.closeScope()
-		ast.Walk(r, n.X)
-		var lhs []ast.Expr
-		if n.Key != nil {
-			lhs = append(lhs, n.Key)
-		}
-		if n.Value != nil {
-			lhs = append(lhs, n.Value)
-		}
-		if len(lhs) > 0 {
-			if n.Tok == token.DEFINE {
-				// Note: we can't exactly match the behavior of object resolution
-				// during the parsing pass here, as it uses the position of the RANGE
-				// token for the RHS OpPos. That information is not contained within
-				// the AST.
-				as := &ast.AssignStmt{
-					Lhs:    lhs,
-					Tok:    token.DEFINE,
-					TokPos: n.TokPos,
-					Rhs:    []ast.Expr{&ast.UnaryExpr{Op: token.RANGE, X: n.X}},
-				}
-				// TODO(rFindley): this walkLHS reproduced the parser resolution, but
-				// is it necessary? By comparison, for a normal AssignStmt we don't
-				// walk the LHS in case there is an invalid identifier list.
-				r.walkLHS(lhs)
-				r.shortVarDecl(as)
-			} else {
-				r.walkExprs(lhs)
-			}
-		}
-		ast.Walk(r, n.Body)
-
-	// Declarations
-	case *ast.GenDecl:
-		switch n.Tok {
-		case token.CONST, token.VAR:
-			for i, spec := range n.Specs {
-				spec := spec.(*ast.ValueSpec)
-				kind := ast.Con
-				if n.Tok == token.VAR {
-					kind = ast.Var
-				}
-				r.walkExprs(spec.Values)
-				if spec.Type != nil {
-					ast.Walk(r, spec.Type)
-				}
-				r.declare(spec, i, r.topScope, kind, spec.Names...)
-			}
-		case token.TYPE:
-			for _, spec := range n.Specs {
-				spec := spec.(*ast.TypeSpec)
-				// Go spec: The scope of a type identifier declared inside a function begins
-				// at the identifier in the TypeSpec and ends at the end of the innermost
-				// containing block.
-				r.declare(spec, nil, r.topScope, ast.Typ, spec.Name)
-				if spec.TypeParams != nil {
-					r.openScope(spec.Pos())
-					r.walkTParams(spec.TypeParams)
-					r.closeScope()
-				}
-				ast.Walk(r, spec.Type)
-			}
-		}
-
-	case *ast.FuncDecl:
-		// Open the function scope.
-		r.openScope(n.Pos())
-		defer r.closeScope()
-
-		r.walkRecv(n.Recv)
-
-		// Type parameters are walked normally: they can reference each other, and
-		// can be referenced by normal parameters.
-		if n.Type.TypeParams != nil {
-			r.walkTParams(n.Type.TypeParams)
-			// TODO(rFindley): need to address receiver type parameters.
-		}
-
-		// Resolve and declare parameters in a specific order to get duplicate
-		// declaration errors in the correct location.
-		r.resolveList(n.Type.Params)
-		r.resolveList(n.Type.Results)
-		r.declareList(n.Recv, ast.Var)
-		r.declareList(n.Type.Params, ast.Var)
-		r.declareList(n.Type.Results, ast.Var)
-
-		r.walkBody(n.Body)
-		if n.Recv == nil && n.Name.Name != "init" {
-			r.declare(n, nil, r.pkgScope, ast.Fun, n.Name)
-		}
-
-	default:
-		return r
-	}
-
-	return nil
-}
-
-func (r *resolver) walkFuncType(typ *ast.FuncType) {
-	// typ.TypeParams must be walked separately for FuncDecls.
-	r.resolveList(typ.Params)
-	r.resolveList(typ.Results)
-	r.declareList(typ.Params, ast.Var)
-	r.declareList(typ.Results, ast.Var)
-}
-
-func (r *resolver) resolveList(list *ast.FieldList) {
-	if list == nil {
-		return
-	}
-	for _, f := range list.List {
-		if f.Type != nil {
-			ast.Walk(r, f.Type)
-		}
-	}
-}
-
-func (r *resolver) declareList(list *ast.FieldList, kind ast.ObjKind) {
-	if list == nil {
-		return
-	}
-	for _, f := range list.List {
-		r.declare(f, nil, r.topScope, kind, f.Names...)
-	}
-}
-
-func (r *resolver) walkRecv(recv *ast.FieldList) {
-	// If our receiver has receiver type parameters, we must declare them before
-	// trying to resolve the rest of the receiver, and avoid re-resolving the
-	// type parameter identifiers.
-	if recv == nil || len(recv.List) == 0 {
-		return // nothing to do
-	}
-	typ := recv.List[0].Type
-	if ptr, ok := typ.(*ast.StarExpr); ok {
-		typ = ptr.X
-	}
-
-	var declareExprs []ast.Expr // exprs to declare
-	var resolveExprs []ast.Expr // exprs to resolve
-	switch typ := typ.(type) {
-	case *ast.IndexExpr:
-		declareExprs = []ast.Expr{typ.Index}
-		resolveExprs = append(resolveExprs, typ.X)
-	case *ast.IndexListExpr:
-		declareExprs = typ.Indices
-		resolveExprs = append(resolveExprs, typ.X)
-	default:
-		resolveExprs = append(resolveExprs, typ)
-	}
-	for _, expr := range declareExprs {
-		if id, _ := expr.(*ast.Ident); id != nil {
-			r.declare(expr, nil, r.topScope, ast.Typ, id)
-		} else {
-			// The receiver type parameter expression is invalid, but try to resolve
-			// it anyway for consistency.
-			resolveExprs = append(resolveExprs, expr)
-		}
-	}
-	for _, expr := range resolveExprs {
-		if expr != nil {
-			ast.Walk(r, expr)
-		}
-	}
-	// The receiver is invalid, but try to resolve it anyway for consistency.
-	for _, f := range recv.List[1:] {
-		if f.Type != nil {
-			ast.Walk(r, f.Type)
-		}
-	}
-}
-
-func (r *resolver) walkFieldList(list *ast.FieldList, kind ast.ObjKind) {
-	if list == nil {
-		return
-	}
-	r.resolveList(list)
-	r.declareList(list, kind)
-}
-
-// walkTParams is like walkFieldList, but declares type parameters eagerly so
-// that they may be resolved in the constraint expressions held in the field
-// Type.
-func (r *resolver) walkTParams(list *ast.FieldList) {
-	r.declareList(list, ast.Typ)
-	r.resolveList(list)
-}
-
-func (r *resolver) walkBody(body *ast.BlockStmt) {
-	if body == nil {
-		return
-	}
-	r.openLabelScope()
-	defer r.closeLabelScope()
-	r.walkStmts(body.List)
-}
--- a/runtime/_overlay/testing/testing.go
+++ b/runtime/_overlay/testing/testing.go
@@ -1 +0,0 @@
-package testing
--- a/runtime/_overlay/testing/testing_go123.go
+++ b/runtime/_overlay/testing/testing_go123.go
--- a/runtime/_overlay/testing/testing_go124.go
+++ b/runtime/_overlay/testing/testing_go124.go
--- a/runtime/internal/clite/tls/tls_stub.go
+++ b/runtime/internal/clite/tls/tls_stub.go
@@ -0,0 +1,34 @@
+//go:build !llgo
+
+/*
+ * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package tls
+
+// Handle is a no-op TLS handle used when building without the llgo tag.
+type Handle[T any] struct{}
+
+// Alloc returns a stub TLS handle that ignores all operations.
+func Alloc[T any](func(*T)) Handle[T] { return Handle[T]{} }
+
+// Get always returns the zero value.
+func (Handle[T]) Get() (zero T) { return zero }
+
+// Set is a no-op.
+func (Handle[T]) Set(T) {}
+
+// Clear is a no-op.
+func (Handle[T]) Clear() {}
--- a/runtime/internal/runtime/defer_tls.go
+++ b/runtime/internal/runtime/defer_tls.go
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package runtime
+
+import "github.com/goplus/llgo/runtime/internal/clite/tls"
+
+var deferTLS = tls.Alloc[*Defer](func(head **Defer) {
+	if head != nil {
+		*head = nil
+	}
+})
+
+// SetThreadDefer associates the current thread with the given defer chain.
+func SetThreadDefer(head *Defer) {
+	deferTLS.Set(head)
+}
+
+// GetThreadDefer returns the current thread's defer chain head.
+func GetThreadDefer() *Defer {
+	return deferTLS.Get()
+}
+
+// ClearThreadDefer resets the current thread's defer chain to nil.
+func ClearThreadDefer() {
+	deferTLS.Clear()
+}
--- a/runtime/internal/runtime/z_defer_gc.go
+++ b/runtime/internal/runtime/z_defer_gc.go
@@ -0,0 +1,33 @@
+//go:build !nogc
+
+/*
+ * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package runtime
+
+import (
+	"unsafe"
+
+	c "github.com/goplus/llgo/runtime/internal/clite"
+	"github.com/goplus/llgo/runtime/internal/clite/bdwgc"
+)
+
+// FreeDeferNode releases a defer argument node allocated from the Boehm heap.
+func FreeDeferNode(ptr unsafe.Pointer) {
+	if ptr != nil {
+		bdwgc.Free(c.Pointer(ptr))
+	}
+}
--- a/runtime/internal/runtime/z_defer_nogc.go
+++ b/runtime/internal/runtime/z_defer_nogc.go
@@ -0,0 +1,32 @@
+//go:build nogc
+
+/*
+ * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package runtime
+
+import (
+	"unsafe"
+
+	c "github.com/goplus/llgo/runtime/internal/clite"
+)
+
+// FreeDeferNode releases the defer node when GC integration is disabled.
+func FreeDeferNode(ptr unsafe.Pointer) {
+	if ptr != nil {
+		c.Free(ptr)
+	}
+}
--- a/runtime/overlay.go
+++ b/runtime/overlay.go
@@ -7,27 +7,11 @@ import (
 //go:embed _overlay/runtime/runtime.go
 var fakeRuntime string

-//go:embed _overlay/go/parser/resolver.go
-var go_parser_resolver string
-
-//go:embed _overlay/testing/testing.go
-var testing_testing string
-
-//go:embed _overlay/testing/testing_go123.go
-var testing_testing_go123 string
-
-//go:embed _overlay/testing/testing_go124.go
-var testing_testing_go124 string
-
 //go:embed _overlay/net/textproto/textproto.go
 var net_textproto string

 var OverlayFiles = map[string]string{
 	"math/exp_amd64.go":          "package math;",
-	"go/parser/resolver.go":      go_parser_resolver,
-	"testing/testing.go":         testing_testing,
-	"testing/testing_go123.go":   testing_testing_go123,
-	"testing/testing_go124.go":   testing_testing_go124,
 	"net/textproto/textproto.go": net_textproto,
 	"runtime/runtime.go":         fakeRuntime,
 }
--- a/ssa/decl.go
+++ b/ssa/decl.go
@@ -294,7 +294,7 @@ func (p Function) NewBuilder() Builder {
 	// TODO(xsw): Finalize may cause panic, so comment it.
 	// b.Finalize()
 	return &aBuilder{b, nil, p, p.Pkg, prog,
-		make(map[Expr]dbgExpr), make(map[*types.Scope]DIScope)}
+		make(map[*types.Scope]DIScope)}
 }

 // HasBody reports whether the function has a body.
--- a/ssa/di.go
+++ b/ssa/di.go
@@ -662,14 +662,8 @@ func (b diBuilder) createExpression(ops []uint64) DIExpression {

 // Copy to alloca'd memory to get declareable address.
 func (b Builder) constructDebugAddr(v Expr) (dbgPtr Expr, dbgVal Expr, exists bool) {
-	if v, ok := b.dbgVars[v]; ok {
-		return v.ptr, v.val, true
-	}
 	t := v.Type.RawType().Underlying()
 	dbgPtr, dbgVal = b.doConstructDebugAddr(v, t)
-	dbgExpr := dbgExpr{dbgPtr, dbgVal}
-	b.dbgVars[v] = dbgExpr
-	b.dbgVars[dbgVal] = dbgExpr
 	return dbgPtr, dbgVal, false
 }

@@ -874,11 +868,7 @@ func (b Builder) DebugFunction(f Function, pos token.Position, bodyPos token.Pos
 }

 func (b Builder) Param(idx int) Expr {
-	p := b.Func.Param(idx)
-	if v, ok := b.dbgVars[p]; ok {
-		return v.val
-	}
-	return p
+	return b.Func.Param(idx)
 }

 // -----------------------------------------------------------------------------
--- a/ssa/eh.go
+++ b/ssa/eh.go
@@ -149,10 +149,6 @@ func (b Builder) Longjmp(jb, retval Expr) {

 // -----------------------------------------------------------------------------

-const (
-	deferKey = "__llgo_defer"
-)
-
 func (p Function) deferInitBuilder() (b Builder, next BasicBlock) {
 	b = p.NewBuilder()
 	next = b.setBlockMoveLast(p.blks[0])
@@ -162,7 +158,6 @@ func (p Function) deferInitBuilder() (b Builder, next BasicBlock) {

 type aDefer struct {
 	nextBit   int          // next defer bit
-	key       Expr         // pthread TLS key
 	data      Expr         // pointer to runtime.Defer
 	bitsPtr   Expr         // pointer to defer bits
 	rethPtr   Expr         // next block of Rethrow
@@ -174,30 +169,6 @@ type aDefer struct {
 	stmts     []func(bits Expr)
 }

-func (p Package) keyInit(name string) {
-	keyVar := p.VarOf(name)
-	if keyVar == nil {
-		return
-	}
-	prog := p.Prog
-	keyVar.InitNil()
-	keyVar.impl.SetLinkage(llvm.LinkOnceAnyLinkage)
-
-	b := p.afterBuilder()
-	eq := b.BinOp(token.EQL, b.Load(keyVar.Expr), prog.IntVal(0, prog.CInt()))
-	b.IfThen(eq, func() {
-		b.pthreadKeyCreate(keyVar.Expr, prog.Nil(prog.VoidPtr()))
-	})
-}
-
-func (p Package) newKey(name string) Global {
-	return p.NewVarEx(name, p.Prog.CIntPtr())
-}
-
-func (b Builder) deferKey() Expr {
-	return b.Load(b.Pkg.newKey(deferKey).Expr)
-}
-
 const (
 	// 0: addr sigjmpbuf
 	// 1: bits uintptr
@@ -230,17 +201,19 @@ func (b Builder) getDefer(kind DoAction) *aDefer {
 		blks := self.MakeBlocks(2)
 		procBlk, rethrowBlk := blks[0], blks[1]

-		key := b.deferKey()
 		zero := prog.Val(uintptr(0))
-		link := Expr{b.pthreadGetspecific(key).impl, prog.DeferPtr()}
+		link := b.Call(b.Pkg.rtFunc("GetThreadDefer"))
 		jb := b.AllocaSigjmpBuf()
-		ptr := b.aggregateAlloca(prog.Defer(), jb.impl, zero.impl, link.impl, procBlk.Addr().impl)
+		ptr := b.aggregateAllocU(prog.Defer(), jb.impl, zero.impl, link.impl, procBlk.Addr().impl)
 		deferData := Expr{ptr, prog.DeferPtr()}
-		b.pthreadSetspecific(key, deferData)
+		b.Call(b.Pkg.rtFunc("SetThreadDefer"), deferData)
 		bitsPtr := b.FieldAddr(deferData, deferBits)
 		rethPtr := b.FieldAddr(deferData, deferRethrow)
 		rundPtr := b.FieldAddr(deferData, deferRunDefers)
 		argsPtr := b.FieldAddr(deferData, deferArgs)
+		// Initialize the args list so later guards (e.g. DeferAlways/DeferInLoop)
+		// can safely detect an empty chain without a prior push.
+		b.Store(argsPtr, prog.Nil(prog.VoidPtr()))

 		czero := prog.IntVal(0, prog.CInt())
 		retval := b.Sigsetjmp(jb, czero)
@@ -253,7 +226,6 @@ func (b Builder) getDefer(kind DoAction) *aDefer {
 		b.If(b.BinOp(token.EQL, retval, czero), next, panicBlk)

 		self.defer_ = &aDefer{
-			key:       key,
 			data:      deferData,
 			bitsPtr:   bitsPtr,
 			rethPtr:   rethPtr,
@@ -278,8 +250,7 @@ func (b Builder) getDefer(kind DoAction) *aDefer {

 // DeferData returns the defer data (*runtime.Defer).
 func (b Builder) DeferData() Expr {
-	key := b.deferKey()
-	return Expr{b.pthreadGetspecific(key).impl, b.Prog.DeferPtr()}
+	return b.Call(b.Pkg.rtFunc("GetThreadDefer"))
 }

 // Defer emits a defer instruction.
@@ -294,14 +265,17 @@ func (b Builder) Defer(kind DoAction, fn Expr, args ...Expr) {
 	case DeferInCond:
 		prog = b.Prog
 		next := self.nextBit
+		if uintptr(next) >= unsafe.Sizeof(uintptr(0))*8 {
+			panic("too many conditional defers")
+		}
 		self.nextBit++
 		bits := b.Load(self.bitsPtr)
 		nextbit = prog.Val(uintptr(1 << next))
 		b.Store(self.bitsPtr, b.BinOp(token.OR, bits, nextbit))
 	case DeferAlways:
 		// nothing to do
-	default:
-		panic("todo: DeferInLoop is not supported - " + b.Func.Name())
+	case DeferInLoop:
+		// Loop defers rely on a dedicated drain loop inserted below.
 	}
 	typ := b.saveDeferArgs(self, fn, args)
 	self.stmts = append(self.stmts, func(bits Expr) {
@@ -314,6 +288,29 @@ func (b Builder) Defer(kind DoAction, fn Expr, args ...Expr) {
 			})
 		case DeferAlways:
 			b.callDefer(self, typ, fn, args)
+		case DeferInLoop:
+			prog := b.Prog
+			condBlk := b.Func.MakeBlock()
+			bodyBlk := b.Func.MakeBlock()
+			exitBlk := b.Func.MakeBlock()
+			// Control flow:
+			//   condBlk: check argsPtr for non-nil to see if there's work to drain.
+			//   bodyBlk: execute a single defer node, then jump back to condBlk.
+			//   exitBlk: reached when the list is empty (argsPtr == nil).
+			// This mirrors runtime's linked-list unwinding semantics for loop defers.
+
+			// jump to condition check before executing
+			b.Jump(condBlk)
+			b.SetBlockEx(condBlk, AtEnd, true)
+			list := b.Load(self.argsPtr)
+			has := b.BinOp(token.NEQ, list, prog.Nil(prog.VoidPtr()))
+			b.If(has, bodyBlk, exitBlk)
+
+			b.SetBlockEx(bodyBlk, AtEnd, true)
+			b.callDefer(self, typ, fn, args)
+			b.Jump(condBlk)
+
+			b.SetBlockEx(exitBlk, AtEnd, true)
 		}
 	})
 }
@@ -354,7 +351,7 @@ func (b Builder) saveDeferArgs(self *aDefer, fn Expr, args []Expr) Type {
 		flds[i+offset] = arg.impl
 	}
 	typ := prog.Struct(typs...)
-	ptr := Expr{b.aggregateMalloc(typ, flds...), prog.VoidPtr()}
+	ptr := Expr{b.aggregateAllocU(typ, flds...), prog.VoidPtr()}
 	b.Store(self.argsPtr, ptr)
 	return typ
 }
@@ -365,19 +362,28 @@ func (b Builder) callDefer(self *aDefer, typ Type, fn Expr, args []Expr) {
 		return
 	}
 	prog := b.Prog
+	zero := prog.Nil(prog.VoidPtr())
+	list := b.Load(self.argsPtr)
+	has := b.BinOp(token.NEQ, list, zero)
+	// The guard is required because callDefer is reused by endDefer() after the
+	// list has been drained. Without this check we would dereference a nil
+	// pointer when no loop defers were recorded.
+	b.IfThen(has, func() {
 		ptr := b.Load(self.argsPtr)
 		data := b.Load(Expr{ptr.impl, prog.Pointer(typ)})
 		offset := 1
 		b.Store(self.argsPtr, Expr{b.getField(data, 0).impl, prog.VoidPtr()})
-	if fn.kind == vkClosure {
-		fn = b.getField(data, 1)
+		callFn := fn
+		if callFn.kind == vkClosure {
+			callFn = b.getField(data, 1)
 			offset++
 		}
 		for i := 0; i < len(args); i++ {
 			args[i] = b.getField(data, i+offset)
 		}
-	b.Call(fn, args...)
-	b.free(ptr)
+		b.Call(callFn, args...)
+		b.Call(b.Pkg.rtFunc("FreeDeferNode"), ptr)
+	})
 }

 // RunDefers emits instructions to run deferred instructions.
@@ -431,7 +437,7 @@ func (p Function) endDefer(b Builder) {
 		}
 	}
 	link := b.getField(b.Load(self.data), deferLink)
-	b.pthreadSetspecific(self.key, link)
+	b.Call(b.Pkg.rtFunc("SetThreadDefer"), link)
 	b.IndirectJump(b.Load(rundPtr), nexts)

 	b.SetBlockEx(panicBlk, AtEnd, false) // panicBlk: exec runDefers and rethrow
--- a/ssa/eh_loop_test.go
+++ b/ssa/eh_loop_test.go
@@ -0,0 +1,53 @@
+//go:build !llgo
+
+/*
+ * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package ssa_test
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/goplus/llgo/ssa"
+	"github.com/goplus/llgo/ssa/ssatest"
+)
+
+func TestDeferInLoopIR(t *testing.T) {
+	prog := ssatest.NewProgram(t, nil)
+	pkg := prog.NewPackage("foo", "foo")
+
+	callee := pkg.NewFunc("callee", ssa.NoArgsNoRet, ssa.InGo)
+	cb := callee.MakeBody(1)
+	cb.Return()
+	cb.EndBuild()
+
+	fn := pkg.NewFunc("main", ssa.NoArgsNoRet, ssa.InGo)
+	b := fn.MakeBody(1)
+	fn.SetRecover(fn.MakeBlock())
+
+	// Ensure entry block has a terminator like real codegen
+	b.Return()
+	b.SetBlockEx(fn.Block(0), ssa.BeforeLast, true)
+
+	b.Defer(ssa.DeferInLoop, callee.Expr)
+	b.EndBuild()
+
+	ir := pkg.Module().String()
+	if !strings.Contains(ir, "icmp ne ptr") {
+		t.Fatalf("expected loop defer condition in IR, got:\n%s", ir)
+	}
+}
--- a/ssa/package.go
+++ b/ssa/package.go
@@ -798,7 +798,6 @@ func (p Package) afterBuilder() Builder {

 // AfterInit is called after the package is initialized (init all packages that depends on).
 func (p Package) AfterInit(b Builder, ret BasicBlock) {
-	p.keyInit(deferKey)
 	doAfterb := p.afterb != nil
 	doPyLoadModSyms := p.pyHasModSyms()
 	if doAfterb || doPyLoadModSyms {
--- a/ssa/ssa_test.go
+++ b/ssa/ssa_test.go
@@ -60,6 +60,42 @@ func TestUnsafeString(t *testing.T) {
 	b.Return()
 }

+func TestTooManyConditionalDefers(t *testing.T) {
+	wd, err := os.Getwd()
+	if err != nil {
+		t.Fatal(err)
+	}
+	os.Chdir("../../runtime")
+	defer os.Chdir(wd)
+
+	prog := NewProgram(nil)
+	prog.SetRuntime(func() *types.Package {
+		fset := token.NewFileSet()
+		imp := packages.NewImporter(fset)
+		pkg, _ := imp.Import(PkgRuntime)
+		return pkg
+	})
+
+	pkg := prog.NewPackage("foo", "foo")
+	target := pkg.NewFunc("f", NoArgsNoRet, InGo)
+	fn := pkg.NewFunc("main", NoArgsNoRet, InGo)
+	fn.SetRecover(fn.MakeBlock())
+	b := fn.MakeBody(1)
+
+	defer func() {
+		if r := recover(); r == nil {
+			t.Fatal("expected panic: too many conditional defers")
+		} else if r != "too many conditional defers" {
+			t.Fatalf("unexpected panic: %v", r)
+		}
+	}()
+
+	b.Return()
+	for i := 0; i < 65; i++ {
+		b.Defer(DeferInCond, target.Expr)
+	}
+}
+
 func TestPointerSize(t *testing.T) {
 	expected := unsafe.Sizeof(uintptr(0))
 	if size := NewProgram(nil).PointerSize(); size != int(expected) {
--- a/ssa/stmt_builder.go
+++ b/ssa/stmt_builder.go
@@ -57,11 +57,6 @@ func (p BasicBlock) Addr() Expr {

 // -----------------------------------------------------------------------------

-type dbgExpr struct {
-	ptr Expr
-	val Expr
-}
-
 type aBuilder struct {
 	impl llvm.Builder
 	blk  BasicBlock
@@ -69,7 +64,6 @@ type aBuilder struct {
 	Pkg  Package
 	Prog Program

-	dbgVars      map[Expr]dbgExpr         // save copied address and values for debug info
 	diScopeCache map[*types.Scope]DIScope // avoid duplicated DILexicalBlock(s)
 }

--- a/test/defer_test.go
+++ b/test/defer_test.go
@@ -0,0 +1,326 @@
+/*
+ * Copyright (c) 2025 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package test
+
+import (
+	"reflect"
+	"strconv"
+	"testing"
+)
+
+// runLoopDefers exercises a defer statement inside a loop and relies on
+// defers executing after the loop but before the function returns.
+func runLoopDefers() (result []int) {
+	for i := 0; i < 3; i++ {
+		v := i
+		defer func() {
+			result = append(result, v)
+		}()
+	}
+	return
+}
+
+func runLoopDeferCount(n int) (count int) {
+	for i := 0; i < n; i++ {
+		defer func() {
+			count++
+		}()
+	}
+	return
+}
+
+func runDeferRecover() (recovered any, ran bool) {
+	defer func() {
+		recovered = recover()
+		ran = true
+	}()
+	panic("defer recover sentinel")
+}
+
+func runNestedLoopDeferOrder() (order []string) {
+	outerNestedLoop(&order)
+	return
+}
+
+func outerNestedLoop(order *[]string) {
+	for i := 0; i < 3; i++ {
+		v := i
+		label := "outer:" + strconv.Itoa(v)
+		defer func(label string) {
+			*order = append(*order, label)
+		}(label)
+	}
+	middleNestedLoop(order)
+}
+
+func middleNestedLoop(order *[]string) {
+	for i := 0; i < 2; i++ {
+		v := i
+		label := "middle:" + strconv.Itoa(v)
+		defer func(label string) {
+			*order = append(*order, label)
+		}(label)
+	}
+	innerNestedLoop(order)
+}
+
+func innerNestedLoop(order *[]string) {
+	for i := 0; i < 4; i++ {
+		v := i
+		label := "inner:" + strconv.Itoa(v)
+		defer func(label string) {
+			*order = append(*order, label)
+		}(label)
+	}
+}
+
+func TestDeferInLoopOrder(t *testing.T) {
+	got := runLoopDefers()
+	want := []int{2, 1, 0}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("unexpected defer order: got %v, want %v", got, want)
+	}
+}
+
+func TestDeferLoopStress(t *testing.T) {
+	const n = 1_000_000
+	if got := runLoopDeferCount(n); got != n {
+		t.Fatalf("unexpected count: got %d, want %d", got, n)
+	}
+}
+
+func TestDeferRecoverHandlesPanic(t *testing.T) {
+	got, ran := runDeferRecover()
+	want := "defer recover sentinel"
+	if !ran {
+		t.Fatalf("recover defer not executed")
+	}
+	str, ok := got.(string)
+	if !ok {
+		t.Fatalf("recover returned %T, want string", got)
+	}
+	if str != want {
+		t.Fatalf("unexpected recover value: got %q, want %q", str, want)
+	}
+}
+
+func TestNestedDeferLoops(t *testing.T) {
+	got := runNestedLoopDeferOrder()
+	want := []string{
+		"inner:3", "inner:2", "inner:1", "inner:0",
+		"middle:1", "middle:0",
+		"outer:2", "outer:1", "outer:0",
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("unexpected nested order: got %v, want %v", got, want)
+	}
+}
+
+func runNestedConditionalDeferWithRecover() (order []string, recovered any) {
+	defer func() { recovered = recover() }()
+	nestedCondOuter(&order)
+	return
+}
+
+func nestedCondOuter(order *[]string) {
+	for i := 0; i < 3; i++ {
+		v := i
+		label := "outer:" + strconv.Itoa(v)
+		if v%2 == 0 {
+			defer func(label string) {
+				*order = append(*order, label)
+			}(label)
+		}
+		nestedCondMiddle(order, v)
+	}
+}
+
+func nestedCondMiddle(order *[]string, v int) {
+	for j := 0; j < 3; j++ {
+		u := j
+		label := "middle:" + strconv.Itoa(u)
+		if u < 2 {
+			defer func(label string) {
+				*order = append(*order, label)
+			}(label)
+		}
+		nestedCondInner(order)
+	}
+	if v == 1 {
+		panic("nested-conditional-boom")
+	}
+}
+
+func nestedCondInner(order *[]string) {
+	for k := 0; k < 2; k++ {
+		w := k
+		label := "inner:" + strconv.Itoa(w)
+		defer func(label string) {
+			*order = append(*order, label)
+		}(label)
+	}
+}
+
+func TestNestedConditionalDeferWithRecover(t *testing.T) {
+	gotOrder, gotRecovered := runNestedConditionalDeferWithRecover()
+	wantRecovered := "nested-conditional-boom"
+	if s, ok := gotRecovered.(string); !ok || s != wantRecovered {
+		t.Fatalf("unexpected recover value: got %v, want %q", gotRecovered, wantRecovered)
+	}
+	wantOrder := []string{
+		"inner:1", "inner:0",
+		"inner:1", "inner:0",
+		"inner:1", "inner:0",
+		"middle:1", "middle:0",
+		"inner:1", "inner:0",
+		"inner:1", "inner:0",
+		"inner:1", "inner:0",
+		"middle:1", "middle:0",
+		"outer:0",
+	}
+	if !reflect.DeepEqual(gotOrder, wantOrder) {
+		t.Fatalf("unexpected nested conditional order: got %v, want %v", gotOrder, wantOrder)
+	}
+}
+
+func callWithRecover(fn func()) (recovered any) {
+	defer func() { recovered = recover() }()
+	fn()
+	return
+}
+
+func loopBranchEven(order *[]string, i int) {
+	label := "even:" + strconv.Itoa(i)
+	defer func() { *order = append(*order, label) }()
+}
+
+func loopBranchOddNoRecover(order *[]string, i int) {
+	label := "odd-wrap:" + strconv.Itoa(i)
+	defer func() { *order = append(*order, label) }()
+	panic("odd-no-recover")
+}
+
+func loopBranchOddLocalRecover(order *[]string, i int) {
+	label := "odd-local:" + strconv.Itoa(i)
+	defer func() { *order = append(*order, label) }()
+	defer func() { _ = recover() }()
+	panic("odd-local-recover")
+}
+
+func runLoopBranchRecoverMixed(n int) (order []string, recoveredVals []any) {
+	for i := 0; i < n; i++ {
+		if i%2 == 0 {
+			loopBranchEven(&order, i)
+		} else if i%4 == 3 {
+			rec := callWithRecover(func() { loopBranchOddNoRecover(&order, i) })
+			recoveredVals = append(recoveredVals, rec)
+		} else {
+			loopBranchOddLocalRecover(&order, i)
+		}
+	}
+	return
+}
+
+func TestLoopBranchRecoverMixed(t *testing.T) {
+	order, recovered := runLoopBranchRecoverMixed(6)
+	wantOrder := []string{
+		"even:0",
+		"odd-local:1",
+		"even:2",
+		"odd-wrap:3",
+		"even:4",
+		"odd-local:5",
+	}
+	if !reflect.DeepEqual(order, wantOrder) {
+		t.Fatalf("unexpected loop/branch order: got %v, want %v", order, wantOrder)
+	}
+	if len(recovered) != 1 {
+		t.Fatalf("unexpected recovered count: got %d, want %d", len(recovered), 1)
+	}
+	if s, ok := recovered[0].(string); !ok || s != "odd-no-recover" {
+		t.Fatalf("unexpected recovered value: got %v, want %q", recovered[0], "odd-no-recover")
+	}
+}
+
+func deepInner(order *[]string) {
+	for i := 0; i < 2; i++ {
+		idx := i
+		label := "inner:" + strconv.Itoa(idx)
+		defer func(label string) {
+			*order = append(*order, label)
+		}(label)
+		if idx == 0 {
+			continue
+		}
+		panic("deep-boom")
+	}
+}
+
+func deepMiddle(order *[]string) {
+	for i := 0; i < 2; i++ {
+		idx := i
+		label := "middle:" + strconv.Itoa(idx)
+		defer func(label string) {
+			*order = append(*order, label)
+		}(label)
+		if idx == 0 {
+			continue
+		}
+		defer func() {
+			if rec := recover(); rec != nil {
+				panic(rec)
+			}
+		}()
+		deepInner(order)
+	}
+}
+
+func deepOuter(order *[]string) (recovered any) {
+	for i := 0; i < 2; i++ {
+		idx := i
+		label := "outer:" + strconv.Itoa(idx)
+		defer func(label string) {
+			*order = append(*order, label)
+		}(label)
+		if idx == 0 {
+			continue
+		}
+		defer func() {
+			if rec := recover(); rec != nil {
+				recovered = rec
+			}
+		}()
+		deepMiddle(order)
+	}
+	return
+}
+
+func TestPanicCrossTwoFunctionsRecover(t *testing.T) {
+	var order []string
+	recovered := deepOuter(&order)
+	if s, ok := recovered.(string); !ok || s != "deep-boom" {
+		t.Fatalf("unexpected recovered value: got %v, want %q", recovered, "deep-boom")
+	}
+	wantOrder := []string{
+		"inner:1", "inner:0",
+		"middle:1", "middle:0",
+		"outer:1", "outer:0",
+	}
+	if !reflect.DeepEqual(order, wantOrder) {
+		t.Fatalf("unexpected cross-function defer order: got %v, want %v", order, wantOrder)
+	}
+}