Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
- // undef / X -> 0
- if (isa<UndefValue>(Op0))
+ // undef / X -> 0 for integer.
+ // undef / X -> undef for FP (the undef could be a snan).
+ if (isa<UndefValue>(Op0)) {
+ if (Op0->getType()->isFPOrFPVector())
+ return ReplaceInstUsesWith(I, Op0);
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ }
// X / undef -> undef
if (isa<UndefValue>(Op1))
Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
- // 0 % X == 0, we don't need to preserve faults!
+ // 0 % X == 0 for integer, we don't need to preserve faults!
if (Constant *LHS = dyn_cast<Constant>(Op0))
if (LHS->isNullValue())
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
- if (isa<UndefValue>(Op0)) // undef % X -> 0
+ if (isa<UndefValue>(Op0)) { // undef % X -> 0
+ if (I.getType()->isFPOrFPVector())
+ return ReplaceInstUsesWith(I, Op0); // X % undef -> undef (could be SNaN)
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ }
if (isa<UndefValue>(Op1))
return ReplaceInstUsesWith(I, Op1); // X % undef -> undef