return nullptr;
}
+/// Fold icmp ({al}shr X, Y), C.
Instruction *InstCombiner::foldICmpShrConstant(ICmpInst &ICI, Instruction *LHSI,
const APInt *RHSV) {
- // FIXME: This check restricts all folds under here to scalar types.
- ConstantInt *RHS = dyn_cast<ConstantInt>(ICI.getOperand(1));
- if (!RHS)
- return nullptr;
+ // An exact shr only shifts out zero bits, so:
+ // icmp eq/ne (shr X, Y), 0 --> icmp eq/ne X, 0
+ CmpInst::Predicate Pred = ICI.getPredicate();
+ BinaryOperator *BO = cast<BinaryOperator>(LHSI);
+ if (ICI.isEquality() && BO->isExact() && BO->hasOneUse() && *RHSV == 0)
+ return new ICmpInst(Pred, BO->getOperand(0), ICI.getOperand(1));
+ // FIXME: This check restricts all folds under here to scalar types.
// Handle equality comparisons of shift-by-constant.
- BinaryOperator *BO = cast<BinaryOperator>(LHSI);
- if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
- if (Instruction *Res = foldICmpShrConstConst(ICI, BO, ShAmt))
- return Res;
- }
+ ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+ if (!ShAmt)
+ return nullptr;
- // Handle exact shr's.
- if (ICI.isEquality() && BO->isExact() && BO->hasOneUse()) {
- if (RHSV->isMinValue())
- return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), RHS);
- }
+ if (Instruction *Res = foldICmpShrConstConst(ICI, BO, ShAmt))
+ return Res;
return nullptr;
}
define <2 x i1> @test39vec(<2 x i32> %X, <2 x i32> %Y) {
; CHECK-LABEL: @test39vec(
-; CHECK-NEXT: [[A:%.*]] = ashr exact <2 x i32> %X, %Y
-; CHECK-NEXT: [[B:%.*]] = icmp eq <2 x i32> [[A]], zeroinitializer
+; CHECK-NEXT: [[B:%.*]] = icmp eq <2 x i32> %X, zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[B]]
;
%A = ashr exact <2 x i32> %X, %Y
define <2 x i1> @test40vec(<2 x i32> %X, <2 x i32> %Y) {
; CHECK-LABEL: @test40vec(
-; CHECK-NEXT: [[A:%.*]] = lshr exact <2 x i32> %X, %Y
-; CHECK-NEXT: [[B:%.*]] = icmp ne <2 x i32> [[A]], zeroinitializer
+; CHECK-NEXT: [[B:%.*]] = icmp ne <2 x i32> %X, zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[B]]
;
%A = lshr exact <2 x i32> %X, %Y