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[Local] Use nusw and nuw flags in emitGEPOffset()

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This commit is contained in:
Nikita Popov
2024-06-04 09:55:57 +02:00
parent 59cb55d384
commit fe56f19c67
2 changed files with 39 additions and 6 deletions
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11
llvm/lib/Analysis/Local.cpp
View File

@@ -25,13 +25,13 @@ Value *llvm::emitGEPOffset(IRBuilderBase *Builder, const DataLayout &DL,
Type *IntIdxTy = DL.getIndexType(GEP->getType());
Value *Result = nullptr;
// If the GEP is inbounds, we know that none of the addressing operations will
// overflow in a signed sense.
bool isInBounds = GEPOp->isInBounds() && !NoAssumptions;
// nusw implies nsw for the offset arithmetic.
bool NSW = GEPOp->hasNoUnsignedSignedWrap() && !NoAssumptions;
bool NUW = GEPOp->hasNoUnsignedWrap() && !NoAssumptions;
auto AddOffset = [&](Value *Offset) {
if (Result)
Result = Builder->CreateAdd(Result, Offset, GEP->getName() + ".offs",
false /*NUW*/, isInBounds /*NSW*/);
NUW, NSW);
else
Result = Offset;
};
@@ -71,8 +71,7 @@ Value *llvm::emitGEPOffset(IRBuilderBase *Builder, const DataLayout &DL,
Scale = Builder->CreateVectorSplat(
cast<VectorType>(IntIdxTy)->getElementCount(), Scale);
// We'll let instcombine(mul) convert this to a shl if possible.
Op = Builder->CreateMul(Op, Scale, GEP->getName() + ".idx", false /*NUW*/,
isInBounds /*NSW*/);
Op = Builder->CreateMul(Op, Scale, GEP->getName() + ".idx", NUW, NSW);
}
AddOffset(Op);
}

34
llvm/test/Transforms/InstCombine/icmp-gep.ll
View File

@@ -546,3 +546,37 @@ define i1 @test_scalable_ij(ptr %foo, i64 %i, i64 %j) {
%cmp = icmp ult ptr %gep1, %gep2
ret i1 %cmp
}
define i1 @gep_nuw(ptr %p, i64 %a, i64 %b, i64 %c, i64 %d) {
; CHECK-LABEL: @gep_nuw(
; CHECK-NEXT: [[GEP1_IDX:%.*]] = shl nuw i64 [[A:%.*]], 2
; CHECK-NEXT: [[GEP1_IDX1:%.*]] = shl nuw i64 [[B:%.*]], 1
; CHECK-NEXT: [[GEP1_OFFS:%.*]] = add nuw i64 [[GEP1_IDX]], [[GEP1_IDX1]]
; CHECK-NEXT: [[GEP2_IDX:%.*]] = shl nuw i64 [[C:%.*]], 3
; CHECK-NEXT: [[GEP2_IDX2:%.*]] = shl nuw i64 [[D:%.*]], 2
; CHECK-NEXT: [[GEP2_OFFS:%.*]] = add nuw i64 [[GEP2_IDX]], [[GEP2_IDX2]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[GEP1_OFFS]], [[GEP2_OFFS]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%gep1 = getelementptr nuw [2 x i16], ptr %p, i64 %a, i64 %b
%gep2 = getelementptr nuw [2 x i32], ptr %p, i64 %c, i64 %d
%cmp = icmp eq ptr %gep1, %gep2
ret i1 %cmp
}
define i1 @gep_nusw(ptr %p, i64 %a, i64 %b, i64 %c, i64 %d) {
; CHECK-LABEL: @gep_nusw(
; CHECK-NEXT: [[GEP1_IDX:%.*]] = shl nsw i64 [[A:%.*]], 2
; CHECK-NEXT: [[GEP1_IDX1:%.*]] = shl nsw i64 [[B:%.*]], 1
; CHECK-NEXT: [[GEP1_OFFS:%.*]] = add nsw i64 [[GEP1_IDX]], [[GEP1_IDX1]]
; CHECK-NEXT: [[GEP2_IDX:%.*]] = shl nsw i64 [[C:%.*]], 3
; CHECK-NEXT: [[GEP2_IDX2:%.*]] = shl nsw i64 [[D:%.*]], 2
; CHECK-NEXT: [[GEP2_OFFS:%.*]] = add nsw i64 [[GEP2_IDX]], [[GEP2_IDX2]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[GEP1_OFFS]], [[GEP2_OFFS]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%gep1 = getelementptr nusw [2 x i16], ptr %p, i64 %a, i64 %b
%gep2 = getelementptr nusw [2 x i32], ptr %p, i64 %c, i64 %d
%cmp = icmp eq ptr %gep1, %gep2
ret i1 %cmp
}