// Otherwise, check to see if the bits shifted out are known to be zero.
// If so, we can compare against the unshifted value:
// (X & 4) >> 1 == 2 --> (X & 4) == 4.
- if (MaskedValueIsZero(LHSI->getOperand(0),
+ if (LHSI->hasOneUse() &&
+ MaskedValueIsZero(LHSI->getOperand(0),
APInt::getLowBitsSet(Comp.getBitWidth(), ShAmtVal))) {
return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
ConstantExpr::getShl(RHS, ShAmt));
}
- if (LHSI->hasOneUse() || RHSV == 0) {
+ if (LHSI->hasOneUse()) {
// Otherwise strength reduce the shift into an and.
APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
Constant *Mask = ConstantInt::get(Val);
--- /dev/null
+; RUN: llvm-as < %s | opt -instcombine -stats -disable-output |& \
+; RUN: grep {Number of insts combined} | grep 5
+
+define i8 @t1(i8 zeroext %x, i8 zeroext %y) zeroext nounwind {
+entry:
+ %tmp1 = lshr i8 %x, 7
+ %cond1 = icmp ne i8 %tmp1, 0
+ br i1 %cond1, label %bb1, label %bb2
+
+bb1:
+ ret i8 %tmp1
+
+bb2:
+ %tmp2 = add i8 %tmp1, %y
+ ret i8 %tmp2
+}
+
+define i8 @t2(i8 zeroext %x) zeroext nounwind {
+entry:
+ %tmp1 = lshr i8 %x, 7
+ %cond1 = icmp ne i8 %tmp1, 0
+ br i1 %cond1, label %bb1, label %bb2
+
+bb1:
+ ret i8 0
+
+bb2:
+ ret i8 1
+}