https://github.com/jongmyeong-choi created
https://github.com/llvm/llvm-project/pull/156643
In C89, for-init variables have function scope, so cleanup should occur at
function exit, not loop exit. This implements deferred cleanup registration for
C89 mode while preserving C99+ behavior.
Fixes #154624
>From 471273e66583dbec3f145c7f5723a4d5b524d15b Mon Sep 17 00:00:00 2001
From: Jongmyeong Choi <cheesec...@gmail.com>
Date: Wed, 3 Sep 2025 18:41:46 +0900
Subject: [PATCH] [CodeGen] Fix cleanup attribute for C89 for-loop init
variables
In C89, for-init variables have function scope, so cleanup should occur
at function exit, not loop exit. This implements deferred cleanup
registration for C89 mode while preserving C99+ behavior.
Fixes #154624
---
clang/lib/CodeGen/CGDecl.cpp | 32 ++++++++++++++++++++++++---
clang/lib/CodeGen/CodeGenFunction.cpp | 6 ++++-
clang/lib/CodeGen/CodeGenFunction.h | 22 ++++++++++++++++++
clang/test/CodeGen/attr-cleanup.c | 25 +++++++++++++++++++++
4 files changed, 81 insertions(+), 4 deletions(-)
diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index 8a1675848e13c..e4a691a161026 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -2230,9 +2230,16 @@ void CodeGenFunction::EmitAutoVarCleanups(const
AutoVarEmission &emission) {
llvm::Constant *F = CGM.GetAddrOfFunction(FD);
assert(F && "Could not find function!");
- const CGFunctionInfo &Info = CGM.getTypes().arrangeFunctionDeclaration(FD);
- EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D,
- CA);
+ // Check if we're in C89 mode and should defer cleanup to function scope
+ bool isC89Mode = !getLangOpts().C99 && !getLangOpts().CPlusPlus;
+ if (isC89Mode) {
+ const CGFunctionInfo &Info =
CGM.getTypes().arrangeFunctionDeclaration(FD);
+ addDeferredFunctionCleanup(F, &Info, &D, CA);
+ } else {
+ const CGFunctionInfo &Info =
CGM.getTypes().arrangeFunctionDeclaration(FD);
+ EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info,
&D,
+ CA);
+ }
}
// If this is a block variable, call _Block_object_destroy
@@ -2963,3 +2970,22 @@ CodeGenModule::getOMPAllocateAlignment(const VarDecl
*VD) {
}
return std::nullopt;
}
+
+void CodeGenFunction::addDeferredFunctionCleanup(llvm::Constant *F,
+ const CGFunctionInfo *Info,
+ const VarDecl *Var,
+ const CleanupAttr *Attribute)
{
+ DeferredFunctionCleanups.emplace_back(F, Info, Var, Attribute);
+}
+
+void CodeGenFunction::processDeferredFunctionCleanups() {
+ // Process all deferred cleanups at function exit
+ for (const auto &cleanup : DeferredFunctionCleanups) {
+ EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup,
+ cleanup.CleanupFn,
+ cleanup.FnInfo,
+ cleanup.Var,
+ cleanup.Attribute);
+ }
+ DeferredFunctionCleanups.clear();
+}
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp
b/clang/lib/CodeGen/CodeGenFunction.cpp
index 652fe672f15e3..0ea33af47343a 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -405,6 +405,10 @@ void CodeGenFunction::FinishFunction(SourceLocation
EndLoc) {
// parameters. Do this in whatever block we're currently in; it's
// important to do this before we enter the return block or return
// edges will be *really* confused.
+
+ // Process deferred function cleanups before checking for regular cleanups
+ processDeferredFunctionCleanups();
+
bool HasCleanups = EHStack.stable_begin() != PrologueCleanupDepth;
bool HasOnlyNoopCleanups =
HasCleanups && EHStack.containsOnlyNoopCleanups(PrologueCleanupDepth);
@@ -422,7 +426,7 @@ void CodeGenFunction::FinishFunction(SourceLocation EndLoc)
{
// fall back to an artificial location if needed.
OAL = ApplyDebugLocation::CreateDefaultArtificial(*this, EndLoc);
}
-
+
PopCleanupBlocks(PrologueCleanupDepth);
}
diff --git a/clang/lib/CodeGen/CodeGenFunction.h
b/clang/lib/CodeGen/CodeGenFunction.h
index fc65199a0f154..19ea1e7e34052 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -392,6 +392,21 @@ class CodeGenFunction : public CodeGenTypeCache {
/// cleanups associated with the parameters.
EHScopeStack::stable_iterator PrologueCleanupDepth;
+ /// Structure for deferred function-level cleanups (e.g., C89 for-init
cleanup variables)
+ struct DeferredCleanupInfo {
+ llvm::Constant *CleanupFn;
+ const CGFunctionInfo *FnInfo;
+ const VarDecl *Var;
+ const CleanupAttr *Attribute;
+
+ DeferredCleanupInfo(llvm::Constant *F, const CGFunctionInfo *Info,
+ const VarDecl *V, const CleanupAttr *A)
+ : CleanupFn(F), FnInfo(Info), Var(V), Attribute(A) {}
+ };
+
+ /// List of cleanups that should be registered at function exit instead of
current scope
+ SmallVector<DeferredCleanupInfo, 4> DeferredFunctionCleanups;
+
/// ReturnBlock - Unified return block.
JumpDest ReturnBlock;
@@ -3470,6 +3485,13 @@ class CodeGenFunction : public CodeGenTypeCache {
void EmitAutoVarCleanups(const AutoVarEmission &emission);
void emitAutoVarTypeCleanup(const AutoVarEmission &emission,
QualType::DestructionKind dtorKind);
+
+ /// Add a cleanup to be deferred until function exit (for C89 for-init
variables)
+ void addDeferredFunctionCleanup(llvm::Constant *CleanupFn, const
CGFunctionInfo *FnInfo,
+ const VarDecl *Var, const CleanupAttr
*Attribute);
+
+ /// Process all deferred function-level cleanups
+ void processDeferredFunctionCleanups();
void MaybeEmitDeferredVarDeclInit(const VarDecl *var);
diff --git a/clang/test/CodeGen/attr-cleanup.c
b/clang/test/CodeGen/attr-cleanup.c
index 755ede86c1382..c723014973332 100644
--- a/clang/test/CodeGen/attr-cleanup.c
+++ b/clang/test/CodeGen/attr-cleanup.c
@@ -5,3 +5,28 @@ void g(void) {
__attribute__((cleanup(f))) void *g;
}
+// Test for cleanup in for-loop initialization (PR #154624)
+// RUN: %clang_cc1 -std=c89 -emit-llvm %s -o - | FileCheck %s
--check-prefix=C89
+// RUN: %clang_cc1 -std=c99 -emit-llvm %s -o - | FileCheck %s
--check-prefix=C99
+
+void cleaner(int *p);
+
+// C89-LABEL: define{{.*}} void @test_for_loop_cleanup()
+// C99-LABEL: define{{.*}} void @test_for_loop_cleanup()
+void test_for_loop_cleanup(void) {
+ for (__attribute__((cleanup(cleaner))) int i = 42; 0;)
+ ;
+
+#ifndef __STDC_VERSION__
+ if (i > 40) {
+ // do something
+ }
+#endif
+}
+
+// C89: if.end:
+// C89-NEXT: call void @cleaner(ptr noundef %i)
+// C89-NEXT: ret void
+
+// C99: for.cond.cleanup:
+// C99-NEXT: call void @cleaner(ptr noundef %i)
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