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[InstCombine] use m_APInt to allow icmp (shr exact X, Y), 0 folds for splat constant vectors

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279472 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sanjay Patel 2016-08-22 20:45:06 +00:00
parent 00a565c2cd
commit e3ecb56f22
2 changed files with 15 additions and 18 deletions
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27
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -2061,25 +2061,24 @@ Instruction *InstCombiner::foldICmpShlConstant(ICmpInst &Cmp, Instruction *Shl,
return nullptr;
}
/// Fold icmp ({al}shr X, Y), C.
Instruction *InstCombiner::foldICmpShrConstant(ICmpInst &ICI, Instruction *LHSI,
const APInt *RHSV) {
// 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.
ConstantInt *RHS = dyn_cast<ConstantInt>(ICI.getOperand(1));
if (!RHS)
// Handle equality comparisons of shift-by-constant.
ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
if (!ShAmt)
return nullptr;
// 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;
}
// 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;
}

6
test/Transforms/InstCombine/icmp.ll
View File

@ -490,8 +490,7 @@ define i1 @test39(i32 %X, i32 %Y) {
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
@ -511,8 +510,7 @@ define i1 @test40(i32 %X, i32 %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