Skip to content

[AggressiveInstCombine] Use AA during store merge #149992

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
nikic merged 1 commit into from
Jul 23, 2025
Merged

[AggressiveInstCombine] Use AA during store merge #149992

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 8 additions & 2 deletions llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -965,6 +965,7 @@ static bool foldConsecutiveStores(BasicBlock &BB, const DataLayout &DL,
if (DL.isBigEndian())
return false;

BatchAAResults BatchAA(AA);
SmallVector<PartStore, 8> Parts;
bool MadeChange = false;
for (Instruction &I : make_early_inc_range(BB)) {
Expand All @@ -980,8 +981,13 @@ static bool foldConsecutiveStores(BasicBlock &BB, const DataLayout &DL,
continue;
}

// FIXME: Use AA to make this more precise.
if (I.mayReadOrWriteMemory() || I.mayThrow()) {
if (Parts.empty())
continue;

if (I.mayThrow() ||
(I.mayReadOrWriteMemory() &&
isModOrRefSet(BatchAA.getModRefInfo(
&I, MemoryLocation::getBeforeOrAfter(Parts[0].PtrBase))))) {
MadeChange |= mergePartStores(Parts, DL, TTI);
Parts.clear();
continue;
Expand Down
14 changes: 2 additions & 12 deletions llvm/test/Transforms/AggressiveInstCombine/X86/store-merge.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -359,13 +359,8 @@ define void @test_aliasing_store(i16 %x, ptr %p, ptr %p2) {
define void @test_non_aliasing_store(i16 %x, ptr noalias %p, ptr noalias %p2) {
; CHECK-LABEL: define void @test_non_aliasing_store(
; CHECK-SAME: i16 [[X:%.*]], ptr noalias [[P:%.*]], ptr noalias [[P2:%.*]]) {
; CHECK-NEXT: [[X_0:%.*]] = trunc i16 [[X]] to i8
; CHECK-NEXT: store i8 [[X_0]], ptr [[P]], align 1
; CHECK-NEXT: store i16 [[X]], ptr [[P]], align 1
; CHECK-NEXT: store i8 0, ptr [[P2]], align 1
; CHECK-NEXT: [[SHR_1:%.*]] = lshr i16 [[X]], 8
; CHECK-NEXT: [[X_1:%.*]] = trunc i16 [[SHR_1]] to i8
; CHECK-NEXT: [[GEP_1:%.*]] = getelementptr i8, ptr [[P]], i64 1
; CHECK-NEXT: store i8 [[X_1]], ptr [[GEP_1]], align 1
; CHECK-NEXT: ret void
;
%x.0 = trunc i16 %x to i8
Expand Down Expand Up @@ -403,13 +398,8 @@ define i8 @test_aliasing_load(i16 %x, ptr %p, ptr %p2) {
define i8 @test_non_aliasing_load(i16 %x, ptr noalias %p, ptr noalias %p2) {
; CHECK-LABEL: define i8 @test_non_aliasing_load(
; CHECK-SAME: i16 [[X:%.*]], ptr noalias [[P:%.*]], ptr noalias [[P2:%.*]]) {
; CHECK-NEXT: [[X_0:%.*]] = trunc i16 [[X]] to i8
; CHECK-NEXT: store i8 [[X_0]], ptr [[P]], align 1
; CHECK-NEXT: store i16 [[X]], ptr [[P]], align 1
; CHECK-NEXT: [[V:%.*]] = load i8, ptr [[P2]], align 1
; CHECK-NEXT: [[SHR_1:%.*]] = lshr i16 [[X]], 8
; CHECK-NEXT: [[X_1:%.*]] = trunc i16 [[SHR_1]] to i8
; CHECK-NEXT: [[GEP_1:%.*]] = getelementptr i8, ptr [[P]], i64 1
; CHECK-NEXT: store i8 [[X_1]], ptr [[GEP_1]], align 1
; CHECK-NEXT: ret i8 [[V]]
;
%x.0 = trunc i16 %x to i8
Expand Down
Loading