[clang] [llvm] [ObjCARC] Completely remove ObjCARCAPElimPass (PR #150717)
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llvm-commits at lists.llvm.org
Fri Jul 25 16:03:04 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: AZero13 (AZero13)
<details>
<summary>Changes</summary>
ObjCARCAPElimPass has been made obsolete now that we remove unused autorelease pools.
---
Full diff: https://github.com/llvm/llvm-project/pull/150717.diff
7 Files Affected:
- (modified) clang/lib/CodeGen/BackendUtil.cpp (-6)
- (modified) llvm/include/llvm/Transforms/ObjCARC.h (-4)
- (modified) llvm/lib/Passes/PassRegistry.def (-1)
- (modified) llvm/lib/Transforms/ObjCARC/CMakeLists.txt (-1)
- (removed) llvm/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp (-156)
- (modified) llvm/test/Transforms/ObjCARC/apelim.ll (+1-1)
- (modified) llvm/test/Transforms/ObjCARC/comdat-ipo.ll (+1-1)
``````````diff
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 1b7257857dd3b..0b8b824fbcd5a 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -1027,12 +1027,6 @@ 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 bb7ccdb2bc187..fd895830cc030 100644
--- a/llvm/lib/Passes/PassRegistry.def
+++ b/llvm/lib/Passes/PassRegistry.def
@@ -119,7 +119,6 @@ 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/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
``````````
</details>
https://github.com/llvm/llvm-project/pull/150717
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