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

Author: kasuga-fj

llvm/lib/Analysis/DependenceAnalysis.cpp

@@ -2587,7 +2587,9 @@ 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)) {

llvm/test/Analysis/DependenceAnalysis/gcd-miv-overflow.ll

@@ -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 [*]!
 ;