diff options
Diffstat (limited to 'llvm')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp | 27 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/icmp.ll | 6 |
2 files changed, 15 insertions, 18 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp index c32821c73f8..68e55c4a66c 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -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) { - // 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; } diff --git a/llvm/test/Transforms/InstCombine/icmp.ll b/llvm/test/Transforms/InstCombine/icmp.ll index 884ddbb2a72..780529c9de6 100644 --- a/llvm/test/Transforms/InstCombine/icmp.ll +++ b/llvm/test/Transforms/InstCombine/icmp.ll @@ -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 |
