diff options
| -rw-r--r-- | llvm/lib/Transforms/Scalar/EarlyCSE.cpp | 9 | ||||
| -rw-r--r-- | llvm/test/Transforms/EarlyCSE/commute.ll | 16 |
2 files changed, 23 insertions, 2 deletions
diff --git a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp index f9c6f88b9ec..f1f07525702 100644 --- a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp +++ b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp @@ -174,12 +174,17 @@ static unsigned getHashValueImpl(SimpleValue Val) { } if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) { + // Compares can be commuted by swapping the comparands and + // updating the predicate. Choose the form that has the + // comparands in sorted order, or in the case of a tie, the + // one with the lower predicate. Value *LHS = CI->getOperand(0); Value *RHS = CI->getOperand(1); CmpInst::Predicate Pred = CI->getPredicate(); - if (Inst->getOperand(0) > Inst->getOperand(1)) { + CmpInst::Predicate SwappedPred = CI->getSwappedPredicate(); + if (std::tie(LHS, Pred) > std::tie(RHS, SwappedPred)) { std::swap(LHS, RHS); - Pred = CI->getSwappedPredicate(); + Pred = SwappedPred; } return hash_combine(Inst->getOpcode(), Pred, LHS, RHS); } diff --git a/llvm/test/Transforms/EarlyCSE/commute.ll b/llvm/test/Transforms/EarlyCSE/commute.ll index 572336c4ec4..0c8639b5e73 100644 --- a/llvm/test/Transforms/EarlyCSE/commute.ll +++ b/llvm/test/Transforms/EarlyCSE/commute.ll @@ -72,6 +72,22 @@ define void @test5(i32 %A, i32 %B, i1* %PA, i1* %PB) { ret void } +; Test degenerate case of commuted compare of identical comparands. + +define void @test6(float %f, i1* %p1, i1* %p2) { +; CHECK-LABEL: @test6( +; CHECK-NEXT: [[C1:%.*]] = fcmp ult float [[F:%.*]], [[F]] +; CHECK-NEXT: store i1 [[C1]], i1* [[P1:%.*]] +; CHECK-NEXT: store i1 [[C1]], i1* [[P2:%.*]] +; CHECK-NEXT: ret void +; + %c1 = fcmp ult float %f, %f + %c2 = fcmp ugt float %f, %f + store i1 %c1, i1* %p1 + store i1 %c2, i1* %p2 + ret void +} + ; Min/max operands may be commuted in the compare and select. define i8 @smin_commute(i8 %a, i8 %b) { |
