defer: enable loop lowering

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)

_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")
 

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))
+}

cl/_testgo/defercomplex/out.ll

@@ -0,0 +1 @@
+;

cl/_testgo/deferloop/in.go

@@ -0,0 +1,7 @@
+package main
+
+func main() {
+	for i := 0; i < 3; i++ {
+		defer println("loop", i)
+	}
+}

cl/_testgo/deferloop/out.ll

@@ -0,0 +1 @@
+;

cl/compile.go

@@ -98,18 +98,19 @@ type pkgInfo struct {
 type none = struct{}
 
 type context struct {
-	prog   llssa.Program
-	pkg    llssa.Package
-	fn     llssa.Function
-	fset   *token.FileSet
-	goProg *ssa.Program
-	goTyps *types.Package
-	goPkg  *ssa.Package
-	pyMod  string
-	skips  map[string]none
-	loaded map[*types.Package]*pkgInfo // loaded packages
-	bvals  map[ssa.Value]llssa.Expr    // block values
-	vargs  map[*ssa.Alloc][]llssa.Expr // varargs
+	prog        llssa.Program
+	pkg         llssa.Package
+	fn          llssa.Function
+	fset        *token.FileSet
+	goProg      *ssa.Program
+	goTyps      *types.Package
+	goPkg       *ssa.Package
+	pyMod       string
+	skips       map[string]none
+	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)
@@ -335,6 +343,9 @@ func isGlobal(v *types.Var) bool {
 }
 
 func (p *context) debugRef(b llssa.Builder, v *ssa.DebugRef) {
+	if !enableDbgSyms || v.Parent().Origin() != nil {
+		return
+	}
 	object := v.Object()
 	variable, ok := object.(*types.Var)
 	if !ok {
@@ -364,6 +375,9 @@ func (p *context) debugRef(b llssa.Builder, v *ssa.DebugRef) {
 }
 
 func (p *context) debugParams(b llssa.Builder, f *ssa.Function) {
+	if !enableDbgSyms || f.Origin() != nil {
+		return
+	}
 	for i, param := range f.Params {
 		variable := param.Object().(*types.Var)
 		pos := p.goProg.Fset.Position(param.Pos())
@@ -371,6 +385,9 @@ 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 +405,7 @@ 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 +800,7 @@ 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 +863,7 @@ 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:
@@ -855,12 +872,21 @@ 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)
+			div := b.DIVarParam(p.fn, pos, v.Name(), t, argNo)
+			if p.paramDIVars != nil {
+				p.paramDIVars[v] = div
+			}
+			return div
 		}
 	}
 	scope := b.DIScope(p.fn, v.Parent())

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.

internal/crosscompile/compile/libc/libc_test.go

@@ -1,3 +1,5 @@
+//go:build !llgo
+
 package libc
 
 import (

runtime/internal/runtime/defer_tls.go

@@ -0,0 +1,35 @@
+/*
+ * 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)
+}
+
+// ClearThreadDefer resets the current thread's defer chain to nil.
+func ClearThreadDefer() {
+	deferTLS.Clear()
+}

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))
+	}
+}

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)
+	}
+}

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.

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)
 }
 
 // -----------------------------------------------------------------------------

ssa/eh.go

@@ -234,13 +234,17 @@ func (b Builder) getDefer(kind DoAction) *aDefer {
 		zero := prog.Val(uintptr(0))
 		link := Expr{b.pthreadGetspecific(key).impl, prog.DeferPtr()}
 		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)
@@ -300,8 +304,10 @@ func (b Builder) Defer(kind DoAction, fn Expr, args ...Expr) {
 		b.Store(self.bitsPtr, b.BinOp(token.OR, bits, nextbit))
 	case DeferAlways:
 		// nothing to do
+	case DeferInLoop:
+		// Loop defers rely on a dedicated drain loop inserted below.
 	default:
-		panic("todo: DeferInLoop is not supported - " + b.Func.Name())
+		panic("unknown defer kind")
 	}
 	typ := b.saveDeferArgs(self, fn, args)
 	self.stmts = append(self.stmts, func(bits Expr) {
@@ -313,7 +319,37 @@ func (b Builder) Defer(kind DoAction, fn Expr, args ...Expr) {
 				b.callDefer(self, typ, fn, args)
 			})
 		case DeferAlways:
+			zero := b.Prog.Nil(b.Prog.VoidPtr())
+			list := b.Load(self.argsPtr)
+			has := b.BinOp(token.NEQ, list, zero)
+			b.IfThen(has, func() {
+				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)
+		default:
+			panic("unknown defer kind")
 		}
 	})
 }
@@ -354,7 +390,7 @@ 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 +401,28 @@ func (b Builder) callDefer(self *aDefer, typ Type, fn Expr, args []Expr) {
 		return
 	}
 	prog := b.Prog
-	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)
-		offset++
-	}
-	for i := 0; i < len(args); i++ {
-		args[i] = b.getField(data, i+offset)
-	}
-	b.Call(fn, args...)
-	b.free(ptr)
+	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()})
+		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(callFn, args...)
+		b.Call(b.Pkg.rtFunc("FreeDeferNode"), ptr)
+	})
 }
 
 // RunDefers emits instructions to run deferred instructions.
@@ -432,6 +477,7 @@ 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

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)
+	}
+}

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)
 }
 

test/defer_test.go

@@ -0,0 +1,60 @@
+//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 test
+
+import (
+	"reflect"
+	"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 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)
+	}
+}