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Skip stack protectors on alloca's which have new metadata to opt out #170229

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5 changes: 5 additions & 0 deletions llvm/lib/CodeGen/StackProtector.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -431,6 +431,11 @@ bool SSPLayoutAnalysis::requiresStackProtector(Function *F,
for (const BasicBlock &BB : *F) {
for (const Instruction &I : BB) {
if (const AllocaInst *AI = dyn_cast<AllocaInst>(&I)) {
if (const MDNode *MD = AI->getMetadata("stack-protector")) {
const auto *CI = mdconst::dyn_extract<ConstantInt>(MD->getOperand(0));
if (CI->isZero())
continue;
}
if (AI->isArrayAllocation()) {
auto RemarkBuilder = [&]() {
return OptimizationRemark(DEBUG_TYPE, "StackProtectorAllocaOrArray",
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58 changes: 58 additions & 0 deletions llvm/test/CodeGen/AArch64/stack-protector-metadata.ll
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@@ -0,0 +1,58 @@
; RUN: llc -mtriple=aarch64-apple-darwin < %s -o - | FileCheck %s

target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-n32:64-S128-Fn32"
target triple = "arm64-apple-darwin25.1.0"

@.str = private unnamed_addr constant [4 x i8] c"%s\0A\00", align 1

; CHECK-LABEL: test1:
; CHECK-NOT: ___stack_chk_guard

; Function Attrs: noinline nounwind optnone
define void @test1(ptr noundef %msg) #0 {
entry:
%msg.addr = alloca ptr, align 8
%a = alloca [1000 x i8], align 1, !stack-protector !2
store ptr %msg, ptr %msg.addr, align 8
%arraydecay = getelementptr inbounds [1000 x i8], ptr %a, i64 0, i64 0
%0 = load ptr, ptr %msg.addr, align 8
%call = call ptr @strcpy(ptr noundef %arraydecay, ptr noundef %0) #3
%arraydecay1 = getelementptr inbounds [1000 x i8], ptr %a, i64 0, i64 0
%call2 = call i32 (ptr, ...) @printf(ptr noundef @.str, ptr noundef %arraydecay1)
ret void
}


; CHECK-LABEL: test2:
; CHECK: ___stack_chk_guard

; Function Attrs: noinline nounwind optnone
define void @test2(ptr noundef %msg) #0 {
entry:
%msg.addr = alloca ptr, align 8
%b = alloca [1000 x i8], align 1
store ptr %msg, ptr %msg.addr, align 8
%arraydecay = getelementptr inbounds [1000 x i8], ptr %b, i64 0, i64 0
%0 = load ptr, ptr %msg.addr, align 8
%call = call ptr @strcpy(ptr noundef %arraydecay, ptr noundef %0) #3
%arraydecay1 = getelementptr inbounds [1000 x i8], ptr %b, i64 0, i64 0
%call2 = call i32 (ptr, ...) @printf(ptr noundef @.str, ptr noundef %arraydecay1)
ret void
}

; Function Attrs: nounwind
declare ptr @strcpy(ptr noundef, ptr noundef) #1

declare i32 @printf(ptr noundef, ...) #2

attributes #0 = { noinline nounwind optnone "no-trapping-math"="true" "stack-protector-buffer-size"="8" ssp }
attributes #1 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
attributes #2 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
attributes #3 = { nounwind }

!llvm.module.flags = !{!0}
!llvm.ident = !{!1}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{!"clang version 22.0.0"}
!2 = !{i32 0}
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