https://github.com/AZero13 updated
https://github.com/llvm/llvm-project/pull/144788
>From e63c64bb71e99e822557b2d80b26d21648e3e0ec Mon Sep 17 00:00:00 2001
From: Rose <gfunni...@gmail.com>
Date: Wed, 18 Jun 2025 16:05:44 -0400
Subject: [PATCH 1/2] [ObjCARC] Delete empty autoreleasepools with no
autoreleases in them
Erase empty autorelease pools that have no autorelease in them
---
.../ObjCARC/ARCRuntimeEntryPoints.h | 16 +++
llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp | 123 +++++++++++++++++-
.../ObjCARC/test_autorelease_pool.ll | 118 +++++++++++++++++
3 files changed, 252 insertions(+), 5 deletions(-)
create mode 100644 llvm/test/Transforms/ObjCARC/test_autorelease_pool.ll
diff --git a/llvm/lib/Transforms/ObjCARC/ARCRuntimeEntryPoints.h
b/llvm/lib/Transforms/ObjCARC/ARCRuntimeEntryPoints.h
index 3fa844eda21cf..6135c7b938a3e 100644
--- a/llvm/lib/Transforms/ObjCARC/ARCRuntimeEntryPoints.h
+++ b/llvm/lib/Transforms/ObjCARC/ARCRuntimeEntryPoints.h
@@ -46,6 +46,8 @@ enum class ARCRuntimeEntryPointKind {
UnsafeClaimRV,
RetainAutorelease,
RetainAutoreleaseRV,
+ AutoreleasePoolPush,
+ AutoreleasePoolPop,
};
/// Declarations for ObjC runtime functions and constants. These are
initialized
@@ -67,6 +69,8 @@ class ARCRuntimeEntryPoints {
UnsafeClaimRV = nullptr;
RetainAutorelease = nullptr;
RetainAutoreleaseRV = nullptr;
+ AutoreleasePoolPush = nullptr;
+ AutoreleasePoolPop = nullptr;
}
Function *get(ARCRuntimeEntryPointKind kind) {
@@ -101,6 +105,12 @@ class ARCRuntimeEntryPoints {
case ARCRuntimeEntryPointKind::RetainAutoreleaseRV:
return getIntrinsicEntryPoint(RetainAutoreleaseRV,
Intrinsic::objc_retainAutoreleaseReturnValue);
+ case ARCRuntimeEntryPointKind::AutoreleasePoolPush:
+ return getIntrinsicEntryPoint(AutoreleasePoolPush,
+ Intrinsic::objc_autoreleasePoolPush);
+ case ARCRuntimeEntryPointKind::AutoreleasePoolPop:
+ return getIntrinsicEntryPoint(AutoreleasePoolPop,
+ Intrinsic::objc_autoreleasePoolPop);
}
llvm_unreachable("Switch should be a covered switch.");
@@ -143,6 +153,12 @@ class ARCRuntimeEntryPoints {
/// Declaration for objc_retainAutoreleaseReturnValue().
Function *RetainAutoreleaseRV = nullptr;
+ /// Declaration for objc_autoreleasePoolPush().
+ Function *AutoreleasePoolPush = nullptr;
+
+ /// Declaration for objc_autoreleasePoolPop().
+ Function *AutoreleasePoolPop = nullptr;
+
Function *getIntrinsicEntryPoint(Function *&Decl, Intrinsic::ID IntID) {
if (Decl)
return Decl;
diff --git a/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
b/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
index 5eb3f51d38945..deec643532c5d 100644
--- a/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
+++ b/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
@@ -39,6 +39,7 @@
#include "llvm/Analysis/ObjCARCAnalysisUtils.h"
#include "llvm/Analysis/ObjCARCInstKind.h"
#include "llvm/Analysis/ObjCARCUtil.h"
+#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/Constant.h"
@@ -132,11 +133,8 @@ static const Value *FindSingleUseIdentifiedObject(const
Value *Arg) {
//
// The second retain and autorelease can be deleted.
-// TODO: It should be possible to delete
-// objc_autoreleasePoolPush and objc_autoreleasePoolPop
-// pairs if nothing is actually autoreleased between them. Also, autorelease
-// calls followed by objc_autoreleasePoolPop calls (perhaps in ObjC++ code
-// after inlining) can be turned into plain release calls.
+// TODO: Autorelease calls followed by objc_autoreleasePoolPop calls (perhaps
in
+// ObjC++ code after inlining) can be turned into plain release calls.
// TODO: Critical-edge splitting. If the optimial insertion point is
// a critical edge, the current algorithm has to fail, because it doesn't
@@ -566,6 +564,8 @@ class ObjCARCOpt {
void OptimizeReturns(Function &F);
+ void OptimizeAutoreleasePools(Function &F);
+
template <typename PredicateT>
static void cloneOpBundlesIf(CallBase *CI,
SmallVectorImpl<OperandBundleDef> &OpBundles,
@@ -2473,6 +2473,11 @@ bool ObjCARCOpt::run(Function &F, AAResults &AA) {
(1 << unsigned(ARCInstKind::AutoreleaseRV))))
OptimizeReturns(F);
+ // Optimizations for autorelease pools.
+ if (UsedInThisFunction & ((1 << unsigned(ARCInstKind::AutoreleasepoolPush)) |
+ (1 << unsigned(ARCInstKind::AutoreleasepoolPop))))
+ OptimizeAutoreleasePools(F);
+
// Gather statistics after optimization.
#ifndef NDEBUG
if (AreStatisticsEnabled()) {
@@ -2485,6 +2490,114 @@ bool ObjCARCOpt::run(Function &F, AAResults &AA) {
return Changed;
}
+/// Optimize autorelease pools by eliminating empty push/pop pairs.
+void ObjCARCOpt::OptimizeAutoreleasePools(Function &F) {
+ LLVM_DEBUG(dbgs() << "\n== ObjCARCOpt::OptimizeAutoreleasePools ==\n");
+
+ OptimizationRemarkEmitter ORE(&F);
+
+ // Process each basic block independently.
+ // TODO: Can we optimize inter-block autorelease pool pairs?
+ // This would involve tracking autorelease pool state across blocks.
+ for (BasicBlock &BB : F) {
+ // Use a stack to track nested autorelease pools
+ SmallVector<std::pair<CallInst *, bool>, 4>
+ PoolStack; // {push_inst, has_autorelease_in_scope}
+
+ for (Instruction &Inst : llvm::make_early_inc_range(BB)) {
+ ARCInstKind Class = GetBasicARCInstKind(&Inst);
+
+ switch (Class) {
+ case ARCInstKind::AutoreleasepoolPush: {
+ // Start tracking a new autorelease pool scope
+ auto *Push = cast<CallInst>(&Inst);
+ PoolStack.push_back(
+ {Push, false}); // {push_inst, has_autorelease_in_scope}
+ LLVM_DEBUG(dbgs() << "Found autorelease pool push: " << *Push << "\n");
+ break;
+ }
+
+ case ARCInstKind::AutoreleasepoolPop: {
+ auto *Pop = cast<CallInst>(&Inst);
+
+ if (PoolStack.empty())
+ break;
+
+ auto &TopPool = PoolStack.back();
+ CallInst *PendingPush = TopPool.first;
+ bool HasAutoreleaseInScope = TopPool.second;
+
+ // Pop the stack - remove this pool scope
+ PoolStack.pop_back();
+
+ // Bail if this pop doesn't match the pending push
+ if (Pop->getArgOperand(0)->stripPointerCasts() != PendingPush)
+ break;
+
+ // Bail if there were autoreleases in this scope
+ if (HasAutoreleaseInScope)
+ break;
+
+ // Optimize: eliminate this empty autorelease pool pair
+ ORE.emit([&]() {
+ return OptimizationRemark(DEBUG_TYPE, "AutoreleasePoolElimination",
+ PendingPush)
+ << "eliminated empty autorelease pool pair";
+ });
+
+ // Replace all uses of push with poison before deletion
+ PendingPush->replaceAllUsesWith(
+ PoisonValue::get(PendingPush->getType()));
+
+ PendingPush->eraseFromParent();
+ Pop->eraseFromParent();
+
+ Changed = true;
+ ++NumNoops;
+ break;
+ }
+ case ARCInstKind::CallOrUser:
+ case ARCInstKind::Call:
+ case ARCInstKind::Autorelease:
+ case ARCInstKind::AutoreleaseRV:
+ case ARCInstKind::FusedRetainAutorelease:
+ case ARCInstKind::FusedRetainAutoreleaseRV:
+ case ARCInstKind::LoadWeak: {
+ // Track that we have autorelease calls in the current pool scope
+ if (!PoolStack.empty()) {
+ PoolStack.back().second = true; // Set has_autorelease_in_scope =
true
+ LLVM_DEBUG(
+ dbgs()
+ << "Found autorelease or potiential autorelease in pool scope: "
+ << Inst << "\n");
+ }
+ break;
+ }
+
+ // Enumerate all remaining ARCInstKind cases explicitly
+ case ARCInstKind::Retain:
+ case ARCInstKind::RetainRV:
+ case ARCInstKind::UnsafeClaimRV:
+ case ARCInstKind::RetainBlock:
+ case ARCInstKind::Release:
+ case ARCInstKind::NoopCast:
+ case ARCInstKind::LoadWeakRetained:
+ case ARCInstKind::StoreWeak:
+ case ARCInstKind::InitWeak:
+ case ARCInstKind::MoveWeak:
+ case ARCInstKind::CopyWeak:
+ case ARCInstKind::DestroyWeak:
+ case ARCInstKind::StoreStrong:
+ case ARCInstKind::IntrinsicUser:
+ case ARCInstKind::User:
+ case ARCInstKind::None:
+ // These instruction kinds don't affect autorelease pool optimization
+ break;
+ }
+ }
+ }
+}
+
/// @}
///
diff --git a/llvm/test/Transforms/ObjCARC/test_autorelease_pool.ll
b/llvm/test/Transforms/ObjCARC/test_autorelease_pool.ll
new file mode 100644
index 0000000000000..ac27211a9e60c
--- /dev/null
+++ b/llvm/test/Transforms/ObjCARC/test_autorelease_pool.ll
@@ -0,0 +1,118 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
UTC_ARGS: --version 5
+; Test for autorelease pool optimizations
+; RUN: opt -passes=objc-arc < %s -S | FileCheck %s
+
+declare ptr @llvm.objc.autoreleasePoolPush()
+declare void @llvm.objc.autoreleasePoolPop(ptr)
+declare ptr @llvm.objc.autorelease(ptr)
+declare ptr @llvm.objc.retain(ptr)
+declare ptr @create_object()
+declare void @use_object(ptr)
+declare ptr @object_with_thing()
+declare void @opaque_callee()
+
+; Test 1: Empty autorelease pool should be eliminated
+define void @test_empty_pool() {
+; CHECK-LABEL: define void @test_empty_pool() {
+; CHECK-NEXT: ret void
+;
+ %pool = call ptr @llvm.objc.autoreleasePoolPush()
+ call void @llvm.objc.autoreleasePoolPop(ptr %pool)
+ ret void
+}
+
+; Test 2: Pool with only release should be removed
+define void @test_autorelease_to_release() {
+; CHECK-LABEL: define void @test_autorelease_to_release() {
+; CHECK-NEXT: [[OBJ:%.*]] = call ptr @create_object()
+; CHECK-NEXT: call void @llvm.objc.release(ptr [[OBJ]]) #[[ATTR0:[0-9]+]],
!clang.imprecise_release [[META0:![0-9]+]]
+; CHECK-NEXT: ret void
+;
+ %obj = call ptr @create_object()
+ %pool = call ptr @llvm.objc.autoreleasePoolPush()
+ call ptr @llvm.objc.autorelease(ptr %obj)
+ call void @llvm.objc.autoreleasePoolPop(ptr %pool)
+ ret void
+}
+
+; Test 3: Pool with autoreleases should not be optimized
+define void @test_multiple_autoreleases() {
+; CHECK-LABEL: define void @test_multiple_autoreleases() {
+; CHECK-NEXT: [[OBJ1:%.*]] = call ptr @create_object()
+; CHECK-NEXT: [[OBJ2:%.*]] = call ptr @create_object()
+; CHECK-NEXT: [[POOL:%.*]] = call ptr @llvm.objc.autoreleasePoolPush()
#[[ATTR0]]
+; CHECK-NEXT: call void @use_object(ptr [[OBJ1]])
+; CHECK-NEXT: [[TMP1:%.*]] = call ptr @llvm.objc.autorelease(ptr [[OBJ1]])
#[[ATTR0]]
+; CHECK-NEXT: call void @use_object(ptr [[OBJ2]])
+; CHECK-NEXT: [[TMP2:%.*]] = call ptr @llvm.objc.autorelease(ptr [[OBJ2]])
#[[ATTR0]]
+; CHECK-NEXT: call void @llvm.objc.autoreleasePoolPop(ptr [[POOL]])
#[[ATTR0]]
+; CHECK-NEXT: ret void
+;
+ %obj1 = call ptr @create_object()
+ %obj2 = call ptr @create_object()
+ %pool = call ptr @llvm.objc.autoreleasePoolPush()
+ call void @use_object(ptr %obj1)
+ call ptr @llvm.objc.autorelease(ptr %obj1)
+ call void @use_object(ptr %obj2)
+ call ptr @llvm.objc.autorelease(ptr %obj2)
+ call void @llvm.objc.autoreleasePoolPop(ptr %pool)
+ ret void
+}
+
+; Test 4: Pool with calls should not be optimized
+define void @test_calls() {
+; CHECK-LABEL: define void @test_calls() {
+; CHECK-NEXT: [[POOL:%.*]] = call ptr @llvm.objc.autoreleasePoolPush()
#[[ATTR0]]
+; CHECK-NEXT: [[OBJ1:%.*]] = call ptr @object_with_thing()
+; CHECK-NEXT: call void @use_object(ptr [[OBJ1]])
+; CHECK-NEXT: call void @llvm.objc.autoreleasePoolPop(ptr [[POOL]])
#[[ATTR0]]
+; CHECK-NEXT: ret void
+;
+ %pool = call ptr @llvm.objc.autoreleasePoolPush()
+ %obj1 = call ptr @object_with_thing()
+ call void @use_object(ptr %obj1)
+ call void @llvm.objc.autoreleasePoolPop(ptr %pool)
+ ret void
+}
+
+; Test 5: Pool with opaque call should not be optimized
+define void @test_opaque_call() {
+; CHECK-LABEL: define void @test_opaque_call() {
+; CHECK-NEXT: [[POOL:%.*]] = call ptr @llvm.objc.autoreleasePoolPush()
#[[ATTR0]]
+; CHECK-NEXT: call void @opaque_callee()
+; CHECK-NEXT: call void @llvm.objc.autoreleasePoolPop(ptr [[POOL]])
#[[ATTR0]]
+; CHECK-NEXT: ret void
+;
+ %pool = call ptr @llvm.objc.autoreleasePoolPush()
+ call void @opaque_callee()
+ call void @llvm.objc.autoreleasePoolPop(ptr %pool)
+ ret void
+}
+
+; Test 6: Nested empty pools should be eliminated
+define void @test_nested_empty_pools() {
+; CHECK-LABEL: define void @test_nested_empty_pools() {
+; CHECK-NEXT: ret void
+;
+ %pool1 = call ptr @llvm.objc.autoreleasePoolPush()
+ %pool2 = call ptr @llvm.objc.autoreleasePoolPush()
+ call void @llvm.objc.autoreleasePoolPop(ptr %pool2)
+ call void @llvm.objc.autoreleasePoolPop(ptr %pool1)
+ ret void
+}
+
+; Test 7: Empty pool with cast should be eliminated
+define void @test_empty_pool_with_cast() {
+; CHECK-LABEL: define void @test_empty_pool_with_cast() {
+; CHECK-NEXT: [[CAST:%.*]] = bitcast ptr poison to ptr
+; CHECK-NEXT: ret void
+;
+ %pool = call ptr @llvm.objc.autoreleasePoolPush()
+ %cast = bitcast ptr %pool to ptr
+ call void @llvm.objc.autoreleasePoolPop(ptr %cast)
+ ret void
+}
+
+;.
+; CHECK: [[META0]] = !{}
+;.
>From f06621062a00a2aba4a86fd214a9c8c57a8b4d30 Mon Sep 17 00:00:00 2001
From: Rose <gfunni...@gmail.com>
Date: Thu, 19 Jun 2025 16:10:14 -0400
Subject: [PATCH 2/2] Delete ObjCARCAPElim, as it is entirely superseded by
ObjCARCOpts
The optimization can be completely superseded now
---
clang/lib/CodeGen/BackendUtil.cpp | 6 -
llvm/include/llvm/Transforms/ObjCARC.h | 4 -
llvm/lib/Passes/PassRegistry.def | 1 -
llvm/lib/Transforms/ObjCARC/CMakeLists.txt | 1 -
llvm/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp | 156 --------------
llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp | 119 +++++++++++
llvm/test/Transforms/ObjCARC/apelim.ll | 2 +-
llvm/test/Transforms/ObjCARC/comdat-ipo.ll | 2 +-
.../ObjCARC/test_autorelease_pool.ll | 201 ++++++++++++++++++
9 files changed, 322 insertions(+), 170 deletions(-)
delete mode 100644 llvm/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp
diff --git a/clang/lib/CodeGen/BackendUtil.cpp
b/clang/lib/CodeGen/BackendUtil.cpp
index 7e0a3cf5591ce..ab2707e0d1c05 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -1022,12 +1022,6 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
MPM.addPass(
createModuleToFunctionPassAdaptor(ObjCARCExpandPass()));
});
- PB.registerPipelineEarlySimplificationEPCallback(
- [](ModulePassManager &MPM, OptimizationLevel Level,
- ThinOrFullLTOPhase) {
- if (Level != OptimizationLevel::O0)
- MPM.addPass(ObjCARCAPElimPass());
- });
PB.registerScalarOptimizerLateEPCallback(
[](FunctionPassManager &FPM, OptimizationLevel Level) {
if (Level != OptimizationLevel::O0)
diff --git a/llvm/include/llvm/Transforms/ObjCARC.h
b/llvm/include/llvm/Transforms/ObjCARC.h
index c927513469a35..c4b4c4f0b09c6 100644
--- a/llvm/include/llvm/Transforms/ObjCARC.h
+++ b/llvm/include/llvm/Transforms/ObjCARC.h
@@ -35,10 +35,6 @@ struct ObjCARCContractPass : public
PassInfoMixin<ObjCARCContractPass> {
LLVM_ABI PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
};
-struct ObjCARCAPElimPass : public PassInfoMixin<ObjCARCAPElimPass> {
- LLVM_ABI PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
-};
-
struct ObjCARCExpandPass : public PassInfoMixin<ObjCARCExpandPass> {
LLVM_ABI PreservedAnalyses run(Function &M, FunctionAnalysisManager &AM);
};
diff --git a/llvm/lib/Passes/PassRegistry.def b/llvm/lib/Passes/PassRegistry.def
index ec14c6a9211d9..6d184d71b92cb 100644
--- a/llvm/lib/Passes/PassRegistry.def
+++ b/llvm/lib/Passes/PassRegistry.def
@@ -113,7 +113,6 @@ MODULE_PASS("module-inline", ModuleInlinerPass())
MODULE_PASS("name-anon-globals", NameAnonGlobalPass())
MODULE_PASS("no-op-module", NoOpModulePass())
MODULE_PASS("nsan", NumericalStabilitySanitizerPass())
-MODULE_PASS("objc-arc-apelim", ObjCARCAPElimPass())
MODULE_PASS("openmp-opt", OpenMPOptPass())
MODULE_PASS("openmp-opt-postlink",
OpenMPOptPass(ThinOrFullLTOPhase::FullLTOPostLink))
diff --git a/llvm/lib/Transforms/ObjCARC/CMakeLists.txt
b/llvm/lib/Transforms/ObjCARC/CMakeLists.txt
index 80867dbc270d7..4274667a2c2b7 100644
--- a/llvm/lib/Transforms/ObjCARC/CMakeLists.txt
+++ b/llvm/lib/Transforms/ObjCARC/CMakeLists.txt
@@ -2,7 +2,6 @@ add_llvm_component_library(LLVMObjCARCOpts
ObjCARC.cpp
ObjCARCOpts.cpp
ObjCARCExpand.cpp
- ObjCARCAPElim.cpp
ObjCARCContract.cpp
DependencyAnalysis.cpp
ProvenanceAnalysis.cpp
diff --git a/llvm/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp
b/llvm/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp
deleted file mode 100644
index dceb2ebb1863e..0000000000000
--- a/llvm/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp
+++ /dev/null
@@ -1,156 +0,0 @@
-//===- ObjCARCAPElim.cpp - ObjC ARC Optimization
--------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM
Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-/// \file
-///
-/// This file defines ObjC ARC optimizations. ARC stands for Automatic
-/// Reference Counting and is a system for managing reference counts for
objects
-/// in Objective C.
-///
-/// This specific file implements optimizations which remove extraneous
-/// autorelease pools.
-///
-/// WARNING: This file knows about certain library functions. It recognizes
them
-/// by name, and hardwires knowledge of their semantics.
-///
-/// WARNING: This file knows about how certain Objective-C library functions
are
-/// used. Naive LLVM IR transformations which would otherwise be
-/// behavior-preserving may break these assumptions.
-///
-//===----------------------------------------------------------------------===//
-
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/Analysis/ObjCARCAnalysisUtils.h"
-#include "llvm/Analysis/ObjCARCInstKind.h"
-#include "llvm/IR/Constants.h"
-#include "llvm/IR/InstrTypes.h"
-#include "llvm/IR/PassManager.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/Transforms/ObjCARC.h"
-
-using namespace llvm;
-using namespace llvm::objcarc;
-
-#define DEBUG_TYPE "objc-arc-ap-elim"
-
-namespace {
-
-/// Interprocedurally determine if calls made by the given call site can
-/// possibly produce autoreleases.
-bool MayAutorelease(const CallBase &CB, unsigned Depth = 0) {
- if (const Function *Callee = CB.getCalledFunction()) {
- if (!Callee->hasExactDefinition())
- return true;
- for (const BasicBlock &BB : *Callee) {
- for (const Instruction &I : BB)
- if (const CallBase *JCB = dyn_cast<CallBase>(&I))
- // This recursion depth limit is arbitrary. It's just great
- // enough to cover known interesting testcases.
- if (Depth < 3 && !JCB->onlyReadsMemory() &&
- MayAutorelease(*JCB, Depth + 1))
- return true;
- }
- return false;
- }
-
- return true;
-}
-
-bool OptimizeBB(BasicBlock *BB) {
- bool Changed = false;
-
- Instruction *Push = nullptr;
- for (Instruction &Inst : llvm::make_early_inc_range(*BB)) {
- switch (GetBasicARCInstKind(&Inst)) {
- case ARCInstKind::AutoreleasepoolPush:
- Push = &Inst;
- break;
- case ARCInstKind::AutoreleasepoolPop:
- // If this pop matches a push and nothing in between can autorelease,
- // zap the pair.
- if (Push && cast<CallInst>(&Inst)->getArgOperand(0) == Push) {
- Changed = true;
- LLVM_DEBUG(dbgs() << "ObjCARCAPElim::OptimizeBB: Zapping push pop "
- "autorelease pair:\n"
- " Pop: "
- << Inst << "\n"
- << " Push: " << *Push
- << "\n");
- Inst.eraseFromParent();
- Push->eraseFromParent();
- }
- Push = nullptr;
- break;
- case ARCInstKind::CallOrUser:
- if (MayAutorelease(cast<CallBase>(Inst)))
- Push = nullptr;
- break;
- default:
- break;
- }
- }
-
- return Changed;
-}
-
-bool runImpl(Module &M) {
- if (!EnableARCOpts)
- return false;
-
- // If nothing in the Module uses ARC, don't do anything.
- if (!ModuleHasARC(M))
- return false;
- // Find the llvm.global_ctors variable, as the first step in
- // identifying the global constructors. In theory, unnecessary autorelease
- // pools could occur anywhere, but in practice it's pretty rare. Global
- // ctors are a place where autorelease pools get inserted automatically,
- // so it's pretty common for them to be unnecessary, and it's pretty
- // profitable to eliminate them.
- GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
- if (!GV)
- return false;
-
- assert(GV->hasDefinitiveInitializer() &&
- "llvm.global_ctors is uncooperative!");
-
- bool Changed = false;
-
- // Dig the constructor functions out of GV's initializer.
- ConstantArray *Init = cast<ConstantArray>(GV->getInitializer());
- for (User::op_iterator OI = Init->op_begin(), OE = Init->op_end();
- OI != OE; ++OI) {
- Value *Op = *OI;
- // llvm.global_ctors is an array of three-field structs where the second
- // members are constructor functions.
- Function *F = dyn_cast<Function>(cast<ConstantStruct>(Op)->getOperand(1));
- // If the user used a constructor function with the wrong signature and
- // it got bitcasted or whatever, look the other way.
- if (!F)
- continue;
- // Only look at function definitions.
- if (F->isDeclaration())
- continue;
- // Only look at functions with one basic block.
- if (std::next(F->begin()) != F->end())
- continue;
- // Ok, a single-block constructor function definition. Try to optimize it.
- Changed |= OptimizeBB(&F->front());
- }
-
- return Changed;
-}
-
-} // namespace
-
-PreservedAnalyses ObjCARCAPElimPass::run(Module &M, ModuleAnalysisManager &AM)
{
- if (!runImpl(M))
- return PreservedAnalyses::all();
- PreservedAnalyses PA;
- PA.preserveSet<CFGAnalyses>();
- return PA;
-}
diff --git a/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
b/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
index deec643532c5d..93cb469da3b46 100644
--- a/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
+++ b/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
@@ -2490,6 +2490,122 @@ bool ObjCARCOpt::run(Function &F, AAResults &AA) {
return Changed;
}
+/// Interprocedurally determine if calls made by the given call site can
+/// possibly produce autoreleases.
+bool MayAutorelease(const CallBase &CB, unsigned Depth = 0) {
+ if (CB.onlyReadsMemory())
+ return false;
+
+ // This recursion depth limit is arbitrary. It's just great
+ // enough to cover known interesting testcases.
+ if (Depth > 5)
+ return true;
+
+ if (const Function *Callee = CB.getCalledFunction()) {
+ if (!Callee->hasExactDefinition())
+ return true;
+ for (const BasicBlock &BB : *Callee) {
+ // If we come across an autoreleasepool push and a pop in the same block,
+ // we can ignore the instructions between them.
+ // TODO: Can we check inter-block autorelease pool pairs?
+ // This would involve tracking autorelease pool state across blocks.
+
+ // First pass: find all push/pop pairs and their positions in this basic
+ // block
+ SmallVector<std::pair<unsigned, unsigned>, 4>
+ ShadowedRegions; // (push_pos, pop_pos)
+ SmallVector<std::pair<unsigned, const Instruction*>, 4> PushStack; //
(index, push_inst)
+
+ unsigned InstIndex = 0;
+ for (const Instruction &I : BB) {
+ if (GetBasicARCInstKind(&I) == ARCInstKind::AutoreleasepoolPush) {
+ PushStack.push_back({InstIndex, &I});
+ } else if (GetBasicARCInstKind(&I) == ARCInstKind::AutoreleasepoolPop)
{
+ if (!PushStack.empty()) {
+ auto [PushIndex, PushInst] = PushStack.back();
+ // Verify this pop actually pops the corresponding push
+ const auto *PopCall = cast<CallInst>(&I);
+ if (PopCall->getArgOperand(0)->stripPointerCasts() == PushInst) {
+ // Valid push/pop pair - add to shadowed regions
+ ShadowedRegions.push_back({PushIndex, InstIndex});
+ PushStack.pop_back();
+ }
+ // If pop doesn't match the most recent push, it might be for an
outer pool
+ // in a different basic block, so we leave the stack unchanged
+ }
+ }
+ InstIndex++;
+ }
+
+ // Second pass: check for autoreleases, ignoring shadowed regions
+ InstIndex = 0;
+ for (const Instruction &I : BB) {
+ // Check if this instruction is in a shadowed region (between inner
+ // push/pop pairs)
+ bool InShadowedRegion = false;
+ for (auto [PushIndex, PopIndex] : ShadowedRegions) {
+ if (InstIndex > PushIndex && InstIndex < PopIndex) {
+ InShadowedRegion = true;
+ break;
+ }
+ }
+
+ if (InShadowedRegion) {
+ InstIndex++;
+ continue; // Skip instructions in shadowed regions - they don't
affect
+ // outer pools
+ }
+
+ ARCInstKind InstKind = GetBasicARCInstKind(&I);
+ switch (InstKind) {
+ case ARCInstKind::Autorelease:
+ case ARCInstKind::AutoreleaseRV:
+ case ARCInstKind::FusedRetainAutorelease:
+ case ARCInstKind::FusedRetainAutoreleaseRV:
+ case ARCInstKind::LoadWeak:
+ // These may produce autoreleases
+ return true;
+
+ case ARCInstKind::Retain:
+ case ARCInstKind::RetainRV:
+ case ARCInstKind::UnsafeClaimRV:
+ case ARCInstKind::RetainBlock:
+ case ARCInstKind::Release:
+ case ARCInstKind::NoopCast:
+ case ARCInstKind::LoadWeakRetained:
+ case ARCInstKind::StoreWeak:
+ case ARCInstKind::InitWeak:
+ case ARCInstKind::MoveWeak:
+ case ARCInstKind::CopyWeak:
+ case ARCInstKind::DestroyWeak:
+ case ARCInstKind::StoreStrong:
+ case ARCInstKind::AutoreleasepoolPush:
+ case ARCInstKind::AutoreleasepoolPop:
+ // These ObjC runtime functions don't produce autoreleases
+ break;
+
+ case ARCInstKind::CallOrUser:
+ case ARCInstKind::Call:
+ // For non-ObjC function calls, recursively analyze
+ if (MayAutorelease(cast<CallBase>(I), Depth + 1))
+ return true;
+ break;
+
+ case ARCInstKind::IntrinsicUser:
+ case ARCInstKind::User:
+ case ARCInstKind::None:
+ // These are not relevant for autorelease analysis
+ break;
+ }
+ InstIndex++;
+ }
+ }
+ return false;
+ }
+
+ return true;
+}
+
/// Optimize autorelease pools by eliminating empty push/pop pairs.
void ObjCARCOpt::OptimizeAutoreleasePools(Function &F) {
LLVM_DEBUG(dbgs() << "\n== ObjCARCOpt::OptimizeAutoreleasePools ==\n");
@@ -2558,6 +2674,9 @@ void ObjCARCOpt::OptimizeAutoreleasePools(Function &F) {
}
case ARCInstKind::CallOrUser:
case ARCInstKind::Call:
+ if (!MayAutorelease(cast<CallBase>(Inst)))
+ break;
+ [[fallthrough]];
case ARCInstKind::Autorelease:
case ARCInstKind::AutoreleaseRV:
case ARCInstKind::FusedRetainAutorelease:
diff --git a/llvm/test/Transforms/ObjCARC/apelim.ll
b/llvm/test/Transforms/ObjCARC/apelim.ll
index 2ac5d15d0df85..01179f3dec048 100644
--- a/llvm/test/Transforms/ObjCARC/apelim.ll
+++ b/llvm/test/Transforms/ObjCARC/apelim.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -passes=objc-arc-apelim < %s | FileCheck %s
+; RUN: opt -S -passes=objc-arc < %s | FileCheck %s
; rdar://10227311
@llvm.global_ctors = appending global [2 x { i32, ptr, ptr }] [{ i32, ptr, ptr
} { i32 65535, ptr @_GLOBAL__I_x, ptr null }, { i32, ptr, ptr } { i32 65535,
ptr @_GLOBAL__I_y, ptr null }]
diff --git a/llvm/test/Transforms/ObjCARC/comdat-ipo.ll
b/llvm/test/Transforms/ObjCARC/comdat-ipo.ll
index 3f91d3bea9f14..d43804c20d936 100644
--- a/llvm/test/Transforms/ObjCARC/comdat-ipo.ll
+++ b/llvm/test/Transforms/ObjCARC/comdat-ipo.ll
@@ -1,4 +1,4 @@
-; RUN: opt -S -passes=objc-arc-apelim < %s | FileCheck %s
+; RUN: opt -S -passes=objc-arc < %s | FileCheck %s
; See PR26774
diff --git a/llvm/test/Transforms/ObjCARC/test_autorelease_pool.ll
b/llvm/test/Transforms/ObjCARC/test_autorelease_pool.ll
index ac27211a9e60c..1238170e0e1fd 100644
--- a/llvm/test/Transforms/ObjCARC/test_autorelease_pool.ll
+++ b/llvm/test/Transforms/ObjCARC/test_autorelease_pool.ll
@@ -113,6 +113,207 @@ define void @test_empty_pool_with_cast() {
ret void
}
+; Test 8: Autorelease shadowing - autorelease in inner pool doesn't prevent
outer optimization
+define void @test_autorelease_shadowing_basic() {
+; CHECK-LABEL: define void @test_autorelease_shadowing_basic() {
+; CHECK-NEXT: [[OBJ:%.*]] = call ptr @create_object()
+; CHECK-NEXT: call void @llvm.objc.release(ptr [[OBJ]]) #[[ATTR0]],
!clang.imprecise_release [[META0]]
+; CHECK-NEXT: ret void
+;
+ %obj = call ptr @create_object()
+ %outer_pool = call ptr @llvm.objc.autoreleasePoolPush()
+
+ ; Inner pool with autorelease - this should be shadowed
+ %inner_pool = call ptr @llvm.objc.autoreleasePoolPush()
+ call ptr @llvm.objc.autorelease(ptr %obj)
+ call void @llvm.objc.autoreleasePoolPop(ptr %inner_pool)
+
+ call void @llvm.objc.autoreleasePoolPop(ptr %outer_pool)
+ ret void
+}
+
+; Test 9: Multiple nested levels with shadowing
+define void @test_multiple_nested_shadowing() {
+; CHECK-LABEL: define void @test_multiple_nested_shadowing() {
+; CHECK-NEXT: [[OBJ1:%.*]] = call ptr @create_object()
+; CHECK-NEXT: [[OBJ2:%.*]] = call ptr @create_object()
+; CHECK-NEXT: call void @llvm.objc.release(ptr [[OBJ1]]) #[[ATTR0]],
!clang.imprecise_release [[META0]]
+; CHECK-NEXT: call void @llvm.objc.release(ptr [[OBJ2]]) #[[ATTR0]],
!clang.imprecise_release [[META0]]
+; CHECK-NEXT: ret void
+;
+ %obj1 = call ptr @create_object()
+ %obj2 = call ptr @create_object()
+ %outer_pool = call ptr @llvm.objc.autoreleasePoolPush()
+
+ ; First inner pool
+ %inner1_pool = call ptr @llvm.objc.autoreleasePoolPush()
+ call ptr @llvm.objc.autorelease(ptr %obj1)
+ call void @llvm.objc.autoreleasePoolPop(ptr %inner1_pool)
+
+ ; Second inner pool with nested level
+ %inner2_pool = call ptr @llvm.objc.autoreleasePoolPush()
+ %inner3_pool = call ptr @llvm.objc.autoreleasePoolPush()
+ call ptr @llvm.objc.autorelease(ptr %obj2)
+ call void @llvm.objc.autoreleasePoolPop(ptr %inner3_pool)
+ call void @llvm.objc.autoreleasePoolPop(ptr %inner2_pool)
+
+ call void @llvm.objc.autoreleasePoolPop(ptr %outer_pool)
+ ret void
+}
+
+; Test 10: Autorelease outside inner pool prevents optimization
+define void @test_autorelease_outside_inner_pool() {
+; CHECK-LABEL: define void @test_autorelease_outside_inner_pool() {
+; CHECK-NEXT: [[OBJ1:%.*]] = call ptr @create_object()
+; CHECK-NEXT: [[OBJ2:%.*]] = call ptr @create_object()
+; CHECK-NEXT: call void @llvm.objc.release(ptr [[OBJ1]]) #[[ATTR0]],
!clang.imprecise_release [[META0]]
+; CHECK-NEXT: call void @llvm.objc.release(ptr [[OBJ2]]) #[[ATTR0]],
!clang.imprecise_release [[META0]]
+; CHECK-NEXT: ret void
+;
+ %obj1 = call ptr @create_object()
+ %obj2 = call ptr @create_object()
+ %outer_pool = call ptr @llvm.objc.autoreleasePoolPush()
+
+ ; This autorelease is NOT in an inner pool, so outer pool can't be optimized
+ call ptr @llvm.objc.autorelease(ptr %obj1)
+
+ ; Inner pool with autorelease (shadowed)
+ %inner_pool = call ptr @llvm.objc.autoreleasePoolPush()
+ call ptr @llvm.objc.autorelease(ptr %obj2)
+ call void @llvm.objc.autoreleasePoolPop(ptr %inner_pool)
+
+ call void @llvm.objc.autoreleasePoolPop(ptr %outer_pool)
+ ret void
+}
+
+; Test 11: Known ObjC functions don't prevent optimization
+define void @test_known_objc_functions() {
+; CHECK-LABEL: define void @test_known_objc_functions() {
+; CHECK-NEXT: [[OBJ:%.*]] = call ptr @create_object()
+; CHECK-NEXT: ret void
+;
+ %obj = call ptr @create_object()
+ %pool = call ptr @llvm.objc.autoreleasePoolPush()
+
+ ; These are all known ObjC runtime functions that don't produce autoreleases
+ %retained = call ptr @llvm.objc.retain(ptr %obj)
+ call void @llvm.objc.release(ptr %obj)
+
+ call void @llvm.objc.autoreleasePoolPop(ptr %pool)
+ ret void
+}
+
+; Test 12: Complex shadowing with mixed autoreleases
+define void @test_complex_shadowing() {
+; CHECK-LABEL: define void @test_complex_shadowing() {
+; CHECK-NEXT: [[OBJ1:%.*]] = call ptr @create_object()
+; CHECK-NEXT: [[OBJ2:%.*]] = call ptr @create_object()
+; CHECK-NEXT: [[OBJ3:%.*]] = call ptr @create_object()
+; CHECK-NEXT: call void @llvm.objc.release(ptr [[OBJ1]]) #[[ATTR0]],
!clang.imprecise_release [[META0]]
+; CHECK-NEXT: call void @llvm.objc.release(ptr [[OBJ2]]) #[[ATTR0]],
!clang.imprecise_release [[META0]]
+; CHECK-NEXT: [[INNER2_POOL:%.*]] = call ptr
@llvm.objc.autoreleasePoolPush() #[[ATTR0]]
+; CHECK-NEXT: [[TMP1:%.*]] = call ptr @llvm.objc.autorelease(ptr [[OBJ3]])
#[[ATTR0]]
+; CHECK-NEXT: call void @llvm.objc.autoreleasePoolPop(ptr [[INNER2_POOL]])
#[[ATTR0]]
+; CHECK-NEXT: ret void
+;
+ %obj1 = call ptr @create_object()
+ %obj2 = call ptr @create_object()
+ %obj3 = call ptr @create_object()
+ %outer_pool = call ptr @llvm.objc.autoreleasePoolPush()
+
+ ; This autorelease is outside inner pools - prevents optimization
+ call ptr @llvm.objc.autorelease(ptr %obj1)
+
+ ; Inner pool 1 with shadowed autorelease
+ %inner1_pool = call ptr @llvm.objc.autoreleasePoolPush()
+ call ptr @llvm.objc.autorelease(ptr %obj2)
+ call void @llvm.objc.autoreleasePoolPop(ptr %inner1_pool)
+
+ ; Some safe ObjC operations
+ %retained = call ptr @llvm.objc.retain(ptr %obj3)
+ call void @llvm.objc.release(ptr %retained)
+
+ ; Inner pool 2 with shadowed autorelease
+ %inner2_pool = call ptr @llvm.objc.autoreleasePoolPush()
+ call ptr @llvm.objc.autorelease(ptr %obj3)
+ call void @llvm.objc.autoreleasePoolPop(ptr %inner2_pool)
+
+ call void @llvm.objc.autoreleasePoolPop(ptr %outer_pool)
+ ret void
+}
+
+; Test 13: Non-ObjC function that may autorelease prevents optimization
+define void @test_non_objc_may_autorelease() {
+; CHECK-LABEL: define void @test_non_objc_may_autorelease() {
+; CHECK-NEXT: [[POOL:%.*]] = call ptr @llvm.objc.autoreleasePoolPush()
#[[ATTR0]]
+; CHECK-NEXT: [[TMP1:%.*]] = call ptr @function_that_might_autorelease()
+; CHECK-NEXT: call void @llvm.objc.autoreleasePoolPop(ptr [[POOL]])
#[[ATTR0]]
+; CHECK-NEXT: ret void
+;
+ %pool = call ptr @llvm.objc.autoreleasePoolPush()
+ call ptr @function_that_might_autorelease()
+ call void @llvm.objc.autoreleasePoolPop(ptr %pool)
+ ret void
+}
+
+; Test 14: Non-ObjC function that doesn't autorelease allows optimization
+define void @test_non_objc_no_autorelease() {
+; CHECK-LABEL: define void @test_non_objc_no_autorelease() {
+; CHECK-NEXT: call void @safe_function()
+; CHECK-NEXT: ret void
+;
+ %pool = call ptr @llvm.objc.autoreleasePoolPush()
+ call void @safe_function()
+ call void @llvm.objc.autoreleasePoolPop(ptr %pool)
+ ret void
+}
+
+; Test 15: Incomplete push/pop pairs across blocks - only inner pairs count
+define void @test_incomplete_pairs_inner_shadowing() {
+; CHECK-LABEL: define void @test_incomplete_pairs_inner_shadowing() {
+; CHECK-NEXT: [[OBJ:%.*]] = call ptr @create_object()
+; CHECK-NEXT: [[OUTER_POOL:%.*]] = call ptr
@llvm.objc.autoreleasePoolPush() #[[ATTR0]]
+; CHECK-NEXT: call void @llvm.objc.release(ptr [[OBJ]]) #[[ATTR0]],
!clang.imprecise_release [[META0]]
+; CHECK-NEXT: ret void
+;
+ %obj = call ptr @create_object()
+ %outer_pool = call ptr @llvm.objc.autoreleasePoolPush()
+
+ ; Inner complete pair - autorelease should be shadowed by this
+ %inner_pool = call ptr @llvm.objc.autoreleasePoolPush()
+ call ptr @llvm.objc.autorelease(ptr %obj) ; This SHOULD be shadowed by
inner pair
+ call void @llvm.objc.autoreleasePoolPop(ptr %inner_pool) ; Completes the
inner pair
+
+ ; Note: %outer_pool pop is in a different block (common pattern)
+ ; But the autorelease was shadowed by the complete inner pair
+ ret void
+}
+
+; Helper functions for testing interprocedural analysis
+
+; Safe function that doesn't call autorelease
+define void @safe_function() {
+ ; Just some computation, no autoreleases
+; CHECK-LABEL: define void @safe_function() {
+; CHECK-NEXT: [[X:%.*]] = add i32 1, 2
+; CHECK-NEXT: ret void
+;
+ %x = add i32 1, 2
+ ret void
+}
+
+; Function that may produce autoreleases (simulated by calling autorelease)
+define ptr @function_that_might_autorelease() {
+; CHECK-LABEL: define ptr @function_that_might_autorelease() {
+; CHECK-NEXT: [[OBJ:%.*]] = call ptr @create_object()
+; CHECK-NEXT: [[AUTORELEASED:%.*]] = call ptr @llvm.objc.autorelease(ptr
[[OBJ]]) #[[ATTR0]]
+; CHECK-NEXT: ret ptr [[AUTORELEASED]]
+;
+ %obj = call ptr @create_object()
+ %autoreleased = call ptr @llvm.objc.autorelease(ptr %obj)
+ ret ptr %autoreleased
+}
+
;.
; CHECK: [[META0]] = !{}
;.
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