diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp | 13 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/apint-add.ll | 2 |
2 files changed, 11 insertions, 4 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp index f94a65a75f0..221a2200717 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -1042,12 +1042,16 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) { if (Value *V = SimplifyUsingDistributiveLaws(I)) return replaceInstUsesWith(I, V); - if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { + const APInt *Val; + if (match(RHS, m_APInt(Val))) { // X + (signbit) --> X ^ signbit - const APInt &Val = CI->getValue(); - if (Val.isSignBit()) + if (Val->isSignBit()) return BinaryOperator::CreateXor(LHS, RHS); + } + // FIXME: Use the match above instead of dyn_cast to allow these transforms + // for splat vectors. + if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { // See if SimplifyDemandedBits can simplify this. This handles stuff like // (X & 254)+1 -> (X&254)|1 if (SimplifyDemandedInstructionBits(I)) @@ -1149,6 +1153,9 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) { return BinaryOperator::CreateSub(SubOne(CRHS), X); } + // FIXME: We already did a check for ConstantInt RHS above this. + // FIXME: Is this pattern covered by another fold? No regression tests fail on + // removal. if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) { // (X & FF00) + xx00 -> (X+xx00) & FF00 Value *X; diff --git a/llvm/test/Transforms/InstCombine/apint-add.ll b/llvm/test/Transforms/InstCombine/apint-add.ll index f27af7b60cc..6740ae66aef 100644 --- a/llvm/test/Transforms/InstCombine/apint-add.ll +++ b/llvm/test/Transforms/InstCombine/apint-add.ll @@ -36,7 +36,7 @@ define i15 @test3(i15 %x) { ; X + signbit --> X ^ signbit define <2 x i5> @test3vec(<2 x i5> %x) { ; CHECK-LABEL: @test3vec( -; CHECK-NEXT: [[Y:%.*]] = add <2 x i5> %x, <i5 -16, i5 -16> +; CHECK-NEXT: [[Y:%.*]] = xor <2 x i5> %x, <i5 -16, i5 -16> ; CHECK-NEXT: ret <2 x i5> [[Y]] ; %y = add <2 x i5> %x, <i5 16, i5 16> |
