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[InstCombine] Preserve nuw in canonicalizeGEPOfConstGEPI8() #151533

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Merged
merged 2 commits into from
Aug 1, 2025
Merged

[InstCombine] Preserve nuw in canonicalizeGEPOfConstGEPI8() #151533

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d1497fe
[InstCombine] Preserve nuw in canonicalizeGEPOfConstGEPI8()
nikic Jul 31, 2025
6a5906d
handle inbounds
nikic Jul 31, 2025
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13 changes: 11 additions & 2 deletions llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2652,9 +2652,18 @@ static Instruction *canonicalizeGEPOfConstGEPI8(GetElementPtrInst &GEP,
APInt NewOffset = TypeSize * *C2 + *C1;
if (NewOffset.isZero() ||
(Src->hasOneUse() && GEP.getOperand(1)->hasOneUse())) {
GEPNoWrapFlags Flags = GEPNoWrapFlags::none();
if (GEP.hasNoUnsignedWrap() &&
cast<GEPOperator>(Src)->hasNoUnsignedWrap() &&
match(GEP.getOperand(1), m_NUWAddLike(m_Value(), m_Value()))) {
Flags |= GEPNoWrapFlags::noUnsignedWrap();
if (GEP.isInBounds() && cast<GEPOperator>(Src)->isInBounds())
Flags |= GEPNoWrapFlags::inBounds();
}

Value *GEPConst =
IC.Builder.CreatePtrAdd(Base, IC.Builder.getInt(NewOffset));
return GetElementPtrInst::Create(BaseType, GEPConst, VarIndex);
IC.Builder.CreatePtrAdd(Base, IC.Builder.getInt(NewOffset), "", Flags);
return GetElementPtrInst::Create(BaseType, GEPConst, VarIndex, Flags);
}

return nullptr;
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180 changes: 180 additions & 0 deletions llvm/test/Transforms/InstCombine/gepofconstgepi8.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -293,3 +293,183 @@ entry:
%p2 = getelementptr <vscale x 4 x i32>, ptr %p1, i64 %index
ret ptr %p2
}

define ptr @test_all_nuw(ptr %base, i64 %a) {
; CHECK-LABEL: define ptr @test_all_nuw(
; CHECK-SAME: ptr [[BASE:%.*]], i64 [[A:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr nuw i8, ptr [[BASE]], i64 9
; CHECK-NEXT: [[P2:%.*]] = getelementptr nuw i32, ptr [[TMP0]], i64 [[A]]
; CHECK-NEXT: ret ptr [[P2]]
;
entry:
%p1 = getelementptr nuw i8, ptr %base, i64 1
%index = add nuw i64 %a, 2
%p2 = getelementptr nuw i32, ptr %p1, i64 %index
ret ptr %p2
}

define ptr @test_all_partial_nuw1(ptr %base, i64 %a) {
; CHECK-LABEL: define ptr @test_all_partial_nuw1(
; CHECK-SAME: ptr [[BASE:%.*]], i64 [[A:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr i8, ptr [[BASE]], i64 9
; CHECK-NEXT: [[P2:%.*]] = getelementptr i32, ptr [[TMP0]], i64 [[A]]
; CHECK-NEXT: ret ptr [[P2]]
;
entry:
%p1 = getelementptr i8, ptr %base, i64 1
%index = add nuw i64 %a, 2
%p2 = getelementptr nuw i32, ptr %p1, i64 %index
ret ptr %p2
}

define ptr @test_all_partial_nuw2(ptr %base, i64 %a) {
; CHECK-LABEL: define ptr @test_all_partial_nuw2(
; CHECK-SAME: ptr [[BASE:%.*]], i64 [[A:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr i8, ptr [[BASE]], i64 9
; CHECK-NEXT: [[P2:%.*]] = getelementptr i32, ptr [[TMP0]], i64 [[A]]
; CHECK-NEXT: ret ptr [[P2]]
;
entry:
%p1 = getelementptr nuw i8, ptr %base, i64 1
%index = add i64 %a, 2
%p2 = getelementptr nuw i32, ptr %p1, i64 %index
ret ptr %p2
}

define ptr @test_all_partial_nuw3(ptr %base, i64 %a) {
; CHECK-LABEL: define ptr @test_all_partial_nuw3(
; CHECK-SAME: ptr [[BASE:%.*]], i64 [[A:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr i8, ptr [[BASE]], i64 9
; CHECK-NEXT: [[P2:%.*]] = getelementptr i32, ptr [[TMP0]], i64 [[A]]
; CHECK-NEXT: ret ptr [[P2]]
;
entry:
%p1 = getelementptr nuw i8, ptr %base, i64 1
%index = add nuw i64 %a, 2
%p2 = getelementptr i32, ptr %p1, i64 %index
ret ptr %p2
}

define ptr @test_all_nuw_disjoint(ptr %base, i64 %a) {
; CHECK-LABEL: define ptr @test_all_nuw_disjoint(
; CHECK-SAME: ptr [[BASE:%.*]], i64 [[A:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr nuw i8, ptr [[BASE]], i64 9
; CHECK-NEXT: [[P2:%.*]] = getelementptr nuw i32, ptr [[TMP0]], i64 [[A]]
; CHECK-NEXT: ret ptr [[P2]]
;
entry:
%p1 = getelementptr nuw i8, ptr %base, i64 1
%index = or disjoint i64 %a, 2
%p2 = getelementptr nuw i32, ptr %p1, i64 %index
ret ptr %p2
}

define ptr @test_all_inbounds_nuw(ptr %base, i64 %a) {
; CHECK-LABEL: define ptr @test_all_inbounds_nuw(
; CHECK-SAME: ptr [[BASE:%.*]], i64 [[A:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr inbounds nuw i8, ptr [[BASE]], i64 9
; CHECK-NEXT: [[P2:%.*]] = getelementptr inbounds nuw i32, ptr [[TMP0]], i64 [[A]]
; CHECK-NEXT: ret ptr [[P2]]
;
entry:
%p1 = getelementptr inbounds nuw i8, ptr %base, i64 1
%index = add nuw i64 %a, 2
%p2 = getelementptr inbounds nuw i32, ptr %p1, i64 %index
ret ptr %p2
}

define ptr @test_all_partial_inbounds1(ptr %base, i64 %a) {
; CHECK-LABEL: define ptr @test_all_partial_inbounds1(
; CHECK-SAME: ptr [[BASE:%.*]], i64 [[A:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr nuw i8, ptr [[BASE]], i64 9
; CHECK-NEXT: [[P2:%.*]] = getelementptr nuw i32, ptr [[TMP0]], i64 [[A]]
; CHECK-NEXT: ret ptr [[P2]]
;
entry:
%p1 = getelementptr nuw i8, ptr %base, i64 1
%index = add nuw i64 %a, 2
%p2 = getelementptr inbounds nuw i32, ptr %p1, i64 %index
ret ptr %p2
}

define ptr @test_all_partial_inbounds2(ptr %base, i64 %a) {
; CHECK-LABEL: define ptr @test_all_partial_inbounds2(
; CHECK-SAME: ptr [[BASE:%.*]], i64 [[A:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr nuw i8, ptr [[BASE]], i64 9
; CHECK-NEXT: [[P2:%.*]] = getelementptr nuw i32, ptr [[TMP0]], i64 [[A]]
; CHECK-NEXT: ret ptr [[P2]]
;
entry:
%p1 = getelementptr inbounds nuw i8, ptr %base, i64 1
%index = add nuw i64 %a, 2
%p2 = getelementptr nuw i32, ptr %p1, i64 %index
ret ptr %p2
}

define ptr @test_all_inbounds_partial_nuw1(ptr %base, i64 %a) {
; CHECK-LABEL: define ptr @test_all_inbounds_partial_nuw1(
; CHECK-SAME: ptr [[BASE:%.*]], i64 [[A:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr i8, ptr [[BASE]], i64 7
; CHECK-NEXT: [[P2:%.*]] = getelementptr i32, ptr [[TMP0]], i64 [[A]]
; CHECK-NEXT: ret ptr [[P2]]
;
entry:
%p1 = getelementptr inbounds i8, ptr %base, i64 -1
%index = add nuw i64 %a, 2
%p2 = getelementptr inbounds nuw i32, ptr %p1, i64 %index
ret ptr %p2
}

define ptr @test_all_inbounds_partial_nuw2(ptr %base, i64 %a) {
; CHECK-LABEL: define ptr @test_all_inbounds_partial_nuw2(
; CHECK-SAME: ptr [[BASE:%.*]], i64 [[A:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr i8, ptr [[BASE]], i64 9
; CHECK-NEXT: [[P2:%.*]] = getelementptr i32, ptr [[TMP0]], i64 [[A]]
; CHECK-NEXT: ret ptr [[P2]]
;
entry:
%p1 = getelementptr inbounds nuw i8, ptr %base, i64 1
%index = add nuw i64 %a, 2
%p2 = getelementptr inbounds i32, ptr %p1, i64 %index
ret ptr %p2
}

define ptr @test_all_inbounds_partial_nuw3(ptr %base, i64 %a) {
; CHECK-LABEL: define ptr @test_all_inbounds_partial_nuw3(
; CHECK-SAME: ptr [[BASE:%.*]], i64 [[A:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr i8, ptr [[BASE]], i64 9
; CHECK-NEXT: [[P2:%.*]] = getelementptr i32, ptr [[TMP0]], i64 [[A]]
; CHECK-NEXT: ret ptr [[P2]]
;
entry:
%p1 = getelementptr inbounds nuw i8, ptr %base, i64 1
%index = add i64 %a, 2
%p2 = getelementptr inbounds nuw i32, ptr %p1, i64 %index
ret ptr %p2
}

define ptr @test_all_nusw_nuw(ptr %base, i64 %a) {
; CHECK-LABEL: define ptr @test_all_nusw_nuw(
; CHECK-SAME: ptr [[BASE:%.*]], i64 [[A:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr nuw i8, ptr [[BASE]], i64 9
; CHECK-NEXT: [[P2:%.*]] = getelementptr nuw i32, ptr [[TMP0]], i64 [[A]]
; CHECK-NEXT: ret ptr [[P2]]
;
entry:
%p1 = getelementptr nusw nuw i8, ptr %base, i64 1
%index = add nsw nuw i64 %a, 2
%p2 = getelementptr nusw nuw i32, ptr %p1, i64 %index
ret ptr %p2
}