(!IsAShr && C->shl(ShAmtVal).lshr(ShAmtVal) == *C)) &&
"Expected icmp+shr simplify did not occur.");
- // Check if the bits shifted out are known to be zero. If so, we can compare
- // against the unshifted value:
+ // If the bits shifted out are known zero, compare the unshifted value:
// (X & 4) >> 1 == 2 --> (X & 4) == 4.
Constant *ShiftedCmpRHS = ConstantInt::get(Shr->getType(), *C << ShAmtVal);
- if (Shr->hasOneUse()) {
- if (Shr->isExact())
- return new ICmpInst(Pred, X, ShiftedCmpRHS);
+ if (Shr->isExact())
+ return new ICmpInst(Pred, X, ShiftedCmpRHS);
- // Otherwise strength reduce the shift into an 'and'.
+ if (Shr->hasOneUse()) {
+ // Canonicalize the shift into an 'and':
+ // icmp eq/ne (shr X, ShAmt), C --> icmp eq/ne (and X, HiMask), (C << ShAmt)
APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
Constant *Mask = ConstantInt::get(Shr->getType(), Val);
Value *And = Builder.CreateAnd(X, Mask, Shr->getName() + ".mask");
define i1 @exact_multiuse(i32 %x) {
; CHECK-LABEL: @exact_multiuse(
; CHECK-NEXT: [[SH:%.*]] = lshr exact i32 %x, 7
-; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[SH]], 1024
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 %x, 131072
; CHECK-NEXT: call void @foo(i32 [[SH]])
; CHECK-NEXT: ret i1 [[CMP]]
;