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[SeparateConstOffsetFromGEP] Check if non-extracted indices may be negative when preserving inbounds #159515

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Merged
merged 1 commit into from
Sep 19, 2025
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[SeparateConstOffsetFromGEP] Check if non-extracted indices may be negative when preserving inbounds #159515

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13 changes: 7 additions & 6 deletions llvm/lib/Transforms/Scalar/SeparateConstOffsetFromGEP.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1116,22 +1116,23 @@ bool SeparateConstOffsetFromGEP::splitGEP(GetElementPtrInst *GEP) {

// Splits this GEP index into a variadic part and a constant offset, and
// uses the variadic part as the new index.
Value *OldIdx = GEP->getOperand(I);
Value *Idx = GEP->getOperand(I);
User *UserChainTail;
bool PreservesNUW;
Value *NewIdx = ConstantOffsetExtractor::Extract(
OldIdx, GEP, UserChainTail, PreservesNUW);
Value *NewIdx = ConstantOffsetExtractor::Extract(Idx, GEP, UserChainTail,
PreservesNUW);
if (NewIdx != nullptr) {
// Switches to the index with the constant offset removed.
GEP->setOperand(I, NewIdx);
// After switching to the new index, we can garbage-collect UserChain
// and the old index if they are not used.
RecursivelyDeleteTriviallyDeadInstructions(UserChainTail);
RecursivelyDeleteTriviallyDeadInstructions(OldIdx);
AllOffsetsNonNegative =
AllOffsetsNonNegative && isKnownNonNegative(NewIdx, *DL);
RecursivelyDeleteTriviallyDeadInstructions(Idx);
Idx = NewIdx;
AllNUWPreserved &= PreservesNUW;
}
AllOffsetsNonNegative =
AllOffsetsNonNegative && isKnownNonNegative(Idx, *DL);
}
}
if (ExtractBase) {
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8 changes: 4 additions & 4 deletions llvm/test/Transforms/SeparateConstOffsetFromGEP/AMDGPU/reorder-gep-inbounds.ll
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Expand Up @@ -279,8 +279,8 @@ define void @addrspace3(ptr addrspace(3) %in.ptr, i64 %in.idx1) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[IN_IDX1_NNEG:%.*]] = and i64 [[IN_IDX1]], 9223372036854775807
; CHECK-NEXT: [[IDXPROM:%.*]] = trunc i64 [[IN_IDX1_NNEG]] to i32
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr inbounds i128, ptr addrspace(3) [[IN_PTR]], i32 [[IDXPROM]]
; CHECK-NEXT: [[IDX11:%.*]] = getelementptr inbounds i8, ptr addrspace(3) [[TMP0]], i32 1024
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr i128, ptr addrspace(3) [[IN_PTR]], i32 [[IDXPROM]]
; CHECK-NEXT: [[IDX11:%.*]] = getelementptr i8, ptr addrspace(3) [[TMP0]], i32 1024
; CHECK-NEXT: ret void
;
entry:
Expand All @@ -296,8 +296,8 @@ define void @addrspace7(ptr addrspace(7) %in.ptr, i64 %in.idx1) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[IN_IDX1_NNEG:%.*]] = and i64 [[IN_IDX1]], 9223372036854775807
; CHECK-NEXT: [[IDXPROM:%.*]] = trunc i64 [[IN_IDX1_NNEG]] to i32
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr inbounds i128, ptr addrspace(7) [[IN_PTR]], i32 [[IDXPROM]]
; CHECK-NEXT: [[IDX11:%.*]] = getelementptr inbounds i8, ptr addrspace(7) [[TMP0]], i32 1024
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr i128, ptr addrspace(7) [[IN_PTR]], i32 [[IDXPROM]]
; CHECK-NEXT: [[IDX11:%.*]] = getelementptr i8, ptr addrspace(7) [[TMP0]], i32 1024
; CHECK-NEXT: ret void
;
entry:
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6 changes: 3 additions & 3 deletions llvm/test/Transforms/SeparateConstOffsetFromGEP/NVPTX/gep-chain.ll
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Expand Up @@ -24,11 +24,11 @@ define i32 @more_interesting(ptr %ptr, i32 %offset1, i32 %offset2) {
; CHECK-NEXT: [[IDXPROM:%.*]] = sext i32 [[OFFSET1]] to i64
; CHECK-NEXT: [[GEP1:%.*]] = getelementptr inbounds [[STRUCT_UCHAR4:%.*]], ptr [[PTR]], i64 [[IDXPROM]]
; CHECK-NEXT: [[IDXPROM1:%.*]] = sext i32 [[OFFSET2]] to i64
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds [[STRUCT_UCHAR4]], ptr [[GEP1]], i64 [[IDXPROM1]]
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i8, ptr [[TMP1]], i64 8
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr [[STRUCT_UCHAR4]], ptr [[GEP1]], i64 [[IDXPROM1]]
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr i8, ptr [[TMP1]], i64 8
; CHECK-NEXT: [[V1:%.*]] = load i32, ptr [[TMP2]], align 4
; CHECK-NEXT: [[IDXPROM2:%.*]] = sext i32 [[OFFSET2]] to i64
; CHECK-NEXT: [[TMP4:%.*]] = getelementptr inbounds [[STRUCT_UCHAR4]], ptr [[TMP1]], i64 [[IDXPROM2]]
; CHECK-NEXT: [[TMP4:%.*]] = getelementptr [[STRUCT_UCHAR4]], ptr [[TMP1]], i64 [[IDXPROM2]]
; CHECK-NEXT: [[V2:%.*]] = load i32, ptr [[TMP4]], align 4
; CHECK-NEXT: [[R:%.*]] = add i32 [[V1]], [[V2]]
; CHECK-NEXT: ret i32 [[R]]
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8 changes: 4 additions & 4 deletions llvm/test/Transforms/SeparateConstOffsetFromGEP/NVPTX/split-gep.ll
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Expand Up @@ -372,8 +372,8 @@ define ptr @trunk_explicit(ptr %ptr, i64 %idx) {
; CHECK-LABEL: define ptr @trunk_explicit(
; CHECK-SAME: ptr [[PTR:%.*]], i64 [[IDX:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr inbounds [[STRUCT0:%.*]], ptr [[PTR]], i64 0, i32 3, i64 [[IDX]], i32 1
; CHECK-NEXT: [[PTR21:%.*]] = getelementptr inbounds i8, ptr [[TMP0]], i64 3216
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr [[STRUCT0:%.*]], ptr [[PTR]], i64 0, i32 3, i64 [[IDX]], i32 1
; CHECK-NEXT: [[PTR21:%.*]] = getelementptr i8, ptr [[TMP0]], i64 3216
; CHECK-NEXT: ret ptr [[PTR21]]
;
entry:
Expand All @@ -389,8 +389,8 @@ define ptr @trunk_long_idx(ptr %ptr, i64 %idx) {
; CHECK-LABEL: define ptr @trunk_long_idx(
; CHECK-SAME: ptr [[PTR:%.*]], i64 [[IDX:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr inbounds [[STRUCT0:%.*]], ptr [[PTR]], i64 0, i32 3, i64 [[IDX]], i32 1
; CHECK-NEXT: [[PTR21:%.*]] = getelementptr inbounds i8, ptr [[TMP0]], i64 3216
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr [[STRUCT0:%.*]], ptr [[PTR]], i64 0, i32 3, i64 [[IDX]], i32 1
; CHECK-NEXT: [[PTR21:%.*]] = getelementptr i8, ptr [[TMP0]], i64 3216
; CHECK-NEXT: ret ptr [[PTR21]]
;
entry:
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