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[DA] Add overflow check when calculating Delta in GCD MIV #169928

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Merged
merged 1 commit into from
Dec 1, 2025
+4 −2
Merged

[DA] Add overflow check when calculating Delta in GCD MIV #169928

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4 changes: 3 additions & 1 deletion llvm/lib/Analysis/DependenceAnalysis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2582,7 +2582,9 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
const SCEV *DstConst = Coefficients;

APInt ExtraGCD = APInt::getZero(BitWidth);
const SCEV *Delta = SE->getMinusSCEV(DstConst, SrcConst);
const SCEV *Delta = minusSCEVNoSignedOverflow(DstConst, SrcConst, *SE);
if (!Delta)
return false;
LLVM_DEBUG(dbgs() << " Delta = " << *Delta << "\n");
const SCEVConstant *Constant = dyn_cast<SCEVConstant>(Delta);
if (const SCEVAddExpr *Sum = dyn_cast<SCEVAddExpr>(Delta)) {
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2 changes: 1 addition & 1 deletion llvm/test/Analysis/DependenceAnalysis/gcd-miv-overflow.ll
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Expand Up @@ -89,7 +89,7 @@ define void @gcdmiv_delta_ovfl(ptr %A) {
; CHECK-GCD-MIV-NEXT: Src: store i8 0, ptr %idx.0, align 1 --> Dst: store i8 0, ptr %idx.0, align 1
; CHECK-GCD-MIV-NEXT: da analyze - consistent output [*]!
; CHECK-GCD-MIV-NEXT: Src: store i8 0, ptr %idx.0, align 1 --> Dst: store i8 1, ptr %idx.1, align 1
; CHECK-GCD-MIV-NEXT: da analyze - none!
; CHECK-GCD-MIV-NEXT: da analyze - consistent output [*|<]!
; CHECK-GCD-MIV-NEXT: Src: store i8 1, ptr %idx.1, align 1 --> Dst: store i8 1, ptr %idx.1, align 1
; CHECK-GCD-MIV-NEXT: da analyze - consistent output [*]!
;
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