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[DirectX] Add a GEP to loads and stores on array allocas #148059

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Merged
merged 6 commits into from
Jul 15, 2025
Merged

[DirectX] Add a GEP to loads and stores on array allocas #148059

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c641da1
Add a GEP to load/stores on array allocas
Icohedron Jul 10, 2025
7e7900a
Apply clang-format
Icohedron Jul 10, 2025
76d8829
Move pass to stage 2 to not conflict with i8 legalization
Icohedron Jul 10, 2025
64bb533
Add tests with i8, and add nuw flag to GEP
Icohedron Jul 10, 2025
d7b908d
Merge remote-tracking branch 'upstream/main' into explicit-load-store…
Icohedron Jul 11, 2025
9ae1593
Set operand instead of replacing instruction
Icohedron Jul 14, 2025
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9 changes: 5 additions & 4 deletions llvm/lib/Target/DirectX/DXILLegalizePass.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -98,9 +98,9 @@ static void fixI8UseChain(Instruction &I,
ElementType = AI->getAllocatedType();
if (auto *GEP = dyn_cast<GetElementPtrInst>(NewOperands[0])) {
ElementType = GEP->getSourceElementType();
if (ElementType->isArrayTy())
ElementType = ElementType->getArrayElementType();
}
if (ElementType->isArrayTy())
ElementType = ElementType->getArrayElementType();
LoadInst *NewLoad = Builder.CreateLoad(ElementType, NewOperands[0]);
ReplacedValues[Load] = NewLoad;
ToRemove.push_back(Load);
Expand Down Expand Up @@ -593,7 +593,8 @@ legalizeLoadStoreOnArrayAllocas(Instruction &I,

IRBuilder<> Builder(&I);
Value *Zero = Builder.getInt32(0);
Value *GEP = Builder.CreateInBoundsGEP(Ty, AllocaPtrOp, {Zero, Zero});
Value *GEP = Builder.CreateGEP(Ty, AllocaPtrOp, {Zero, Zero}, "",
GEPNoWrapFlags::all());

Value *NewLoadStore = nullptr;
if (auto *LI = dyn_cast<LoadInst>(&I))
Expand Down Expand Up @@ -649,14 +650,14 @@ class DXILLegalizationPipeline {
LegalizationPipeline[Stage1].push_back(legalizeMemCpy);
LegalizationPipeline[Stage1].push_back(removeMemSet);
LegalizationPipeline[Stage1].push_back(updateFnegToFsub);
LegalizationPipeline[Stage1].push_back(legalizeLoadStoreOnArrayAllocas);
// Note: legalizeGetHighLowi64Bytes and
// downcastI64toI32InsertExtractElements both modify extractelement, so they
// must run staggered stages. legalizeGetHighLowi64Bytes runs first b\c it
// removes extractelements, reducing the number that
// downcastI64toI32InsertExtractElements needs to handle.
LegalizationPipeline[Stage2].push_back(
downcastI64toI32InsertExtractElements);
LegalizationPipeline[Stage2].push_back(legalizeLoadStoreOnArrayAllocas);
}
};

Expand Down
10 changes: 6 additions & 4 deletions llvm/test/CodeGen/DirectX/legalize-i8.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -127,10 +127,9 @@ define i32 @i8_geps_index0() {
; CHECK: [[LOAD:%.*]] = load i32, ptr [[GEP]], align 4
; CHECK-NEXT: ret i32 [[LOAD]]
%1 = alloca [2 x i32], align 8
%2 = getelementptr inbounds nuw i8, ptr %1, i32 0
%3 = load i8, ptr %2
%4 = sext i8 %3 to i32
ret i32 %4
%2 = load i8, ptr %1
%3 = sext i8 %2 to i32
ret i32 %3
}

define i32 @i8_geps_index1() {
Expand All @@ -149,11 +148,14 @@ define i32 @i8_geps_index1() {
define i32 @i8_gep_store() {
; CHECK-LABEL: define i32 @i8_gep_store(
; CHECK-NEXT: [[ALLOCA:%.*]] = alloca [2 x i32], align 8
; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds nuw [2 x i32], ptr [[ALLOCA]], i32 0, i32 0
; CHECK-NEXT: store i32 0, ptr [[GEP]], align 4
; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds nuw [2 x i32], ptr [[ALLOCA]], i32 0, i32 1
; CHECK-NEXT: store i32 1, ptr [[GEP]], align 4
; CHECK: [[LOAD:%.*]] = load i32, ptr [[GEP]], align 4
; CHECK-NEXT: ret i32 [[LOAD]]
%1 = alloca [2 x i32], align 8
store i8 0, ptr %1
%2 = getelementptr inbounds nuw i8, ptr %1, i32 4
store i8 1, ptr %2
%3 = load i8, ptr %2
Expand Down
4 changes: 2 additions & 2 deletions llvm/test/CodeGen/DirectX/legalize-load-store-array-alloca.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
define float @load() {
; CHECK-LABEL: define float @load
; CHECK-NEXT: [[ALLOCA:%.*]] = alloca [2 x float], align 4
; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds [2 x float], ptr [[ALLOCA]], i32 0, i32 0
; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds nuw [2 x float], ptr [[ALLOCA]], i32 0, i32 0
; CHECK-NEXT: [[LOAD:%.*]] = load float, ptr [[GEP]], align 4
; CHECK-NEXT: ret float [[LOAD]]
%a = alloca [2 x float], align 4
Expand All @@ -14,7 +14,7 @@ define float @load() {
define void @store() {
; CHECK-LABEL: define void @store
; CHECK-NEXT: [[ALLOCA:%.*]] = alloca [3 x i32], align 4
; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds [3 x i32], ptr [[ALLOCA]], i32 0, i32 0
; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds nuw [3 x i32], ptr [[ALLOCA]], i32 0, i32 0
; CHECK-NEXT: store i32 0, ptr [[GEP]], align 4
; CHECK-NEXT: ret void
%a = alloca [3 x i32], align 4
Expand Down
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