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release/20.x: [GlobalOpt] Do not promote malloc if there are atomic loads/stores (#137158) #137179

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Merged
merged 1 commit into from
Apr 29, 2025
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release/20.x: [GlobalOpt] Do not promote malloc if there are atomic loads/stores (#137158) #137179

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4 changes: 4 additions & 0 deletions llvm/lib/Transforms/IPO/GlobalOpt.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -719,10 +719,14 @@ static bool allUsesOfLoadedValueWillTrapIfNull(const GlobalVariable *GV) {
const Value *P = Worklist.pop_back_val();
for (const auto *U : P->users()) {
if (auto *LI = dyn_cast<LoadInst>(U)) {
if (!LI->isSimple())
return false;
SmallPtrSet<const PHINode *, 8> PHIs;
if (!AllUsesOfValueWillTrapIfNull(LI, PHIs))
return false;
} else if (auto *SI = dyn_cast<StoreInst>(U)) {
if (!SI->isSimple())
return false;
// Ignore stores to the global.
if (SI->getPointerOperand() != P)
return false;
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28 changes: 28 additions & 0 deletions llvm/test/Transforms/GlobalOpt/malloc-promote-atomic.ll
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@@ -0,0 +1,28 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt -passes=globalopt -S < %s | FileCheck %s

@g = internal global ptr null, align 8

define void @init() {
; CHECK-LABEL: define void @init() local_unnamed_addr {
; CHECK-NEXT: [[ALLOC:%.*]] = call ptr @malloc(i64 48)
; CHECK-NEXT: store atomic ptr [[ALLOC]], ptr @g seq_cst, align 8
; CHECK-NEXT: ret void
;
%alloc = call ptr @malloc(i64 48)
store atomic ptr %alloc, ptr @g seq_cst, align 8
ret void
}

define i1 @check() {
; CHECK-LABEL: define i1 @check() local_unnamed_addr {
; CHECK-NEXT: [[VAL:%.*]] = load atomic ptr, ptr @g seq_cst, align 8
; CHECK-NEXT: [[CMP:%.*]] = icmp eq ptr [[VAL]], null
; CHECK-NEXT: ret i1 [[CMP]]
;
%val = load atomic ptr, ptr @g seq_cst, align 8
%cmp = icmp eq ptr %val, null
ret i1 %cmp
}

declare ptr @malloc(i64) allockind("alloc,uninitialized") allocsize(0)
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