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[InstCombine] Use intersectForOffsetAdd() in CommonPointerBase #157851

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Merged
merged 1 commit into from
Sep 10, 2025
+17 −5
Merged

[InstCombine] Use intersectForOffsetAdd() in CommonPointerBase #157851

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16 changes: 14 additions & 2 deletions llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2115,6 +2115,7 @@ CommonPointerBase CommonPointerBase::compute(Value *LHS, Value *RHS) {
}

// Find common base and collect RHS GEPs.
bool First = true;
while (true) {
if (Ptrs.contains(RHS)) {
Base.Ptr = RHS;
Expand All @@ -2123,7 +2124,12 @@ CommonPointerBase CommonPointerBase::compute(Value *LHS, Value *RHS) {

if (auto *GEP = dyn_cast<GEPOperator>(RHS)) {
Base.RHSGEPs.push_back(GEP);
Base.RHSNW &= GEP->getNoWrapFlags();
if (First) {
First = false;
Base.RHSNW = GEP->getNoWrapFlags();
} else {
Base.RHSNW = Base.RHSNW.intersectForOffsetAdd(GEP->getNoWrapFlags());
}
RHS = GEP->getPointerOperand();
} else {
// No common base.
Expand All @@ -2132,13 +2138,19 @@ CommonPointerBase CommonPointerBase::compute(Value *LHS, Value *RHS) {
}

// Collect LHS GEPs.
First = true;
while (true) {
if (LHS == Base.Ptr)
break;

auto *GEP = cast<GEPOperator>(LHS);
Base.LHSGEPs.push_back(GEP);
Base.LHSNW &= GEP->getNoWrapFlags();
if (First) {
First = false;
Base.LHSNW = GEP->getNoWrapFlags();
} else {
Base.LHSNW = Base.LHSNW.intersectForOffsetAdd(GEP->getNoWrapFlags());
}
LHS = GEP->getPointerOperand();
}

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6 changes: 3 additions & 3 deletions llvm/test/Transforms/InstCombine/icmp-gep.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -838,9 +838,9 @@ define i1 @gep_mugtiple_ugt_not_all_nuw(ptr %base, i64 %idx, i64 %idx2) {

define i1 @gep_mugtiple_ugt_inbounds_nusw(ptr %base, i64 %idx, i64 %idx2) {
; CHECK-LABEL: @gep_mugtiple_ugt_inbounds_nusw(
; CHECK-NEXT: [[GEP1_IDX1:%.*]] = add i64 [[IDX:%.*]], [[IDX2:%.*]]
; CHECK-NEXT: [[TMP1:%.*]] = shl i64 [[GEP1_IDX1]], 2
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i64 [[TMP1]], 0
; CHECK-NEXT: [[GEP1:%.*]] = getelementptr inbounds i32, ptr [[BASE:%.*]], i64 [[IDX:%.*]]
; CHECK-NEXT: [[GEP2:%.*]] = getelementptr nusw i32, ptr [[GEP1]], i64 [[IDX2:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt ptr [[GEP2]], [[BASE]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%gep1 = getelementptr inbounds i32, ptr %base, i64 %idx
Expand Down