static ConstantInt *Multiply(ConstantInt *C1, ConstantInt *C2) {
return ConstantInt::get(C1->getValue() * C2->getValue());
}
+/// MultiplyOverflows - True if the multiply can not be expressed in an int
+/// this size.
+static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
+ uint32_t W = C1->getBitWidth();
+ APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
+ if (sign) {
+ LHSExt.sext(W * 2);
+ RHSExt.sext(W * 2);
+ } else {
+ LHSExt.zext(W * 2);
+ RHSExt.zext(W * 2);
+ }
+
+ APInt MulExt = LHSExt * RHSExt;
+
+ if (sign) {
+ APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
+ APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
+ return MulExt.slt(Min) || MulExt.sgt(Max);
+ } else
+ return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
+}
/// ComputeMaskedBits - Determine which of the bits specified in Mask are
/// known to be either zero or one and return them in the KnownZero/KnownOne
if (Instruction *LHS = dyn_cast<Instruction>(Op0))
if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
- return BinaryOperator::create(I.getOpcode(), LHS->getOperand(0),
- Multiply(RHS, LHSRHS));
+ if (MultiplyOverflows(RHS, LHSRHS, I.getOpcode()==Instruction::SDiv))
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ else
+ return BinaryOperator::create(I.getOpcode(), LHS->getOperand(0),
+ Multiply(RHS, LHSRHS));
}
if (!RHS->isZero()) { // avoid X udiv 0