default:
return true;
case Instruction::UDiv:
- case Instruction::URem:
- // x / y is undefined if y == 0, but calculations like x / 3 are safe.
- return isKnownNonZero(Inst->getOperand(1), TD);
+ case Instruction::URem: {
+ // x / y is undefined if y == 0.
+ const APInt *V;
+ if (match(Inst->getOperand(1), m_APInt(V)))
+ return *V != 0;
+ return false;
+ }
case Instruction::SDiv:
case Instruction::SRem: {
- Value *Op = Inst->getOperand(1);
- // x / y is undefined if y == 0
- if (!isKnownNonZero(Op, TD))
- return false;
- // x / y might be undefined if y == -1
- unsigned BitWidth = getBitWidth(Op->getType(), TD);
- if (BitWidth == 0)
- return false;
- APInt KnownZero(BitWidth, 0);
- APInt KnownOne(BitWidth, 0);
- computeKnownBits(Op, KnownZero, KnownOne, TD);
- return !!KnownZero;
+ // x / y is undefined if y == 0 or x == INT_MIN and y == -1
+ const APInt *X, *Y;
+ if (match(Inst->getOperand(1), m_APInt(Y))) {
+ if (*Y != 0) {
+ if (*Y == -1) {
+ // The numerator can't be MinSignedValue if the denominator is -1.
+ if (match(Inst->getOperand(0), m_APInt(X)))
+ return !Y->isMinSignedValue();
+ // The numerator *might* be MinSignedValue.
+ return false;
+ }
+ // The denominator is not 0 or -1, it's safe to proceed.
+ return true;
+ }
+ }
+ return false;
}
case Instruction::Load: {
const LoadInst *LI = cast<LoadInst>(Inst);