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[SimplifyCFG] Only consider provenance capture in store speculation (#138548)

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The capture check here is to protect against concurrent accesses from
other threads. This requires the provenance to escape.
This commit is contained in:
Nikita Popov 2025-05-22 17:01:37 +02:00 committed by GitHub
parent fb21efa258
commit eee958285b
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GPG Key ID: B5690EEEBB952194
2 changed files with 5 additions and 6 deletions
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4
llvm/lib/Transforms/Utils/SimplifyCFG.cpp
View File

@ -3067,7 +3067,9 @@ static Value *isSafeToSpeculateStore(Instruction *I, BasicBlock *BrBB,
Value *Obj = getUnderlyingObject(StorePtr); Value *Obj = getUnderlyingObject(StorePtr);
bool ExplicitlyDereferenceableOnly; bool ExplicitlyDereferenceableOnly;
if (isWritableObject(Obj, ExplicitlyDereferenceableOnly) && if (isWritableObject(Obj, ExplicitlyDereferenceableOnly) &&
!PointerMayBeCaptured(Obj, /*ReturnCaptures=*/false) && capturesNothing(
PointerMayBeCaptured(Obj, /*ReturnCaptures=*/false,
CaptureComponents::Provenance)) &&
(!ExplicitlyDereferenceableOnly || (!ExplicitlyDereferenceableOnly ||
isDereferenceablePointer(StorePtr, StoreTy, isDereferenceablePointer(StorePtr, StoreTy,
LI->getDataLayout()))) { LI->getDataLayout()))) {

7
llvm/test/Transforms/SimplifyCFG/speculate-store.ll
View File

@ -203,11 +203,8 @@ define i32 @load_before_store_escape_addr_only(i64 %i, i32 %b) {
; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds [2 x i32], ptr [[A]], i64 0, i64 [[I:%.*]] ; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds [2 x i32], ptr [[A]], i64 0, i64 [[I:%.*]]
; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[ARRAYIDX]], align 4 ; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[ARRAYIDX]], align 4
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[TMP0]], [[B:%.*]] ; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[TMP0]], [[B:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_END:%.*]] ; CHECK-NEXT: [[SPEC_STORE_SELECT:%.*]] = select i1 [[CMP]], i32 [[B]], i32 [[TMP0]]
; CHECK: if.then: ; CHECK-NEXT: store i32 [[SPEC_STORE_SELECT]], ptr [[ARRAYIDX]], align 4
; CHECK-NEXT: store i32 [[B]], ptr [[ARRAYIDX]], align 4
; CHECK-NEXT: br label [[IF_END]]
; CHECK: if.end:
; CHECK-NEXT: [[TMP1:%.*]] = load i32, ptr [[A]], align 4 ; CHECK-NEXT: [[TMP1:%.*]] = load i32, ptr [[A]], align 4
; CHECK-NEXT: [[ARRAYIDX2:%.*]] = getelementptr inbounds [2 x i32], ptr [[A]], i64 0, i64 1 ; CHECK-NEXT: [[ARRAYIDX2:%.*]] = getelementptr inbounds [2 x i32], ptr [[A]], i64 0, i64 1
; CHECK-NEXT: [[TMP2:%.*]] = load i32, ptr [[ARRAYIDX2]], align 4 ; CHECK-NEXT: [[TMP2:%.*]] = load i32, ptr [[ARRAYIDX2]], align 4