diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp | 89 |
1 files changed, 55 insertions, 34 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp index f320f125bf6..17a6fb9a402 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp @@ -2374,6 +2374,58 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) { return Changed ? &I : nullptr; } +/// A ^ B can be specified using other logic ops in a variety of patterns. We +/// can fold these early and efficiently by morphing an existing instruction. +static Instruction *foldXorToXor(BinaryOperator &I) { + assert(I.getOpcode() == Instruction::Xor); + Value *Op0 = I.getOperand(0); + Value *Op1 = I.getOperand(1); + Value *A, *B; + + // There are 4 commuted variants for each of the basic patterns. + + // (A & B) ^ (A | B) -> A ^ B + // (A & B) ^ (B | A) -> A ^ B + // (A | B) ^ (A & B) -> A ^ B + // (A | B) ^ (B & A) -> A ^ B + if ((match(Op0, m_And(m_Value(A), m_Value(B))) && + match(Op1, m_c_Or(m_Specific(A), m_Specific(B)))) || + (match(Op0, m_Or(m_Value(A), m_Value(B))) && + match(Op1, m_c_And(m_Specific(A), m_Specific(B))))) { + I.setOperand(0, A); + I.setOperand(1, B); + return &I; + } + + // (A | ~B) ^ (~A | B) -> A ^ B + // (~B | A) ^ (~A | B) -> A ^ B + // (~A | B) ^ (A | ~B) -> A ^ B + // (B | ~A) ^ (A | ~B) -> A ^ B + if ((match(Op0, m_c_Or(m_Value(A), m_Not(m_Value(B)))) && + match(Op1, m_Or(m_Not(m_Specific(A)), m_Specific(B)))) || + (match(Op0, m_c_Or(m_Not(m_Value(A)), m_Value(B))) && + match(Op1, m_Or(m_Specific(A), m_Not(m_Specific(B)))))) { + I.setOperand(0, A); + I.setOperand(1, B); + return &I; + } + + // (A & ~B) ^ (~A & B) -> A ^ B + // (~B & A) ^ (~A & B) -> A ^ B + // (~A & B) ^ (A & ~B) -> A ^ B + // (B & ~A) ^ (A & ~B) -> A ^ B + if ((match(Op0, m_c_And(m_Value(A), m_Not(m_Value(B)))) && + match(Op1, m_And(m_Not(m_Specific(A)), m_Specific(B)))) || + (match(Op0, m_c_And(m_Not(m_Value(A)), m_Value(B))) && + match(Op1, m_And(m_Specific(A), m_Not(m_Specific(B)))))) { + I.setOperand(0, A); + I.setOperand(1, B); + return &I; + } + + return nullptr; +} + // FIXME: We use commutative matchers (m_c_*) for some, but not all, matches // here. We should standardize that construct where it is needed or choose some // other way to ensure that commutated variants of patterns are not missed. @@ -2387,6 +2439,9 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) { if (Value *V = SimplifyXorInst(Op0, Op1, DL, &TLI, &DT, &AC)) return replaceInstUsesWith(I, V); + if (Instruction *NewXor = foldXorToXor(I)) + return NewXor; + // (A&B)^(A&C) -> A&(B^C) etc if (Value *V = SimplifyUsingDistributiveLaws(I)) return replaceInstUsesWith(I, V); @@ -2569,40 +2624,6 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) { { Value *A, *B, *C, *D; - // (A & B)^(A | B) -> A ^ B - if (match(Op0, m_And(m_Value(A), m_Value(B))) && - match(Op1, m_Or(m_Value(C), m_Value(D)))) { - if ((A == C && B == D) || (A == D && B == C)) - return BinaryOperator::CreateXor(A, B); - } - // (A | B)^(A & B) -> A ^ B - if (match(Op0, m_Or(m_Value(A), m_Value(B))) && - match(Op1, m_And(m_Value(C), m_Value(D)))) { - if ((A == C && B == D) || (A == D && B == C)) - return BinaryOperator::CreateXor(A, B); - } - // (A | ~B) ^ (~A | B) -> A ^ B - // (~B | A) ^ (~A | B) -> A ^ B - if (match(Op0, m_c_Or(m_Value(A), m_Not(m_Value(B)))) && - match(Op1, m_Or(m_Not(m_Specific(A)), m_Specific(B)))) - return BinaryOperator::CreateXor(A, B); - - // (~A | B) ^ (A | ~B) -> A ^ B - if (match(Op0, m_Or(m_Not(m_Value(A)), m_Value(B))) && - match(Op1, m_Or(m_Specific(A), m_Not(m_Specific(B))))) { - return BinaryOperator::CreateXor(A, B); - } - // (A & ~B) ^ (~A & B) -> A ^ B - // (~B & A) ^ (~A & B) -> A ^ B - if (match(Op0, m_c_And(m_Value(A), m_Not(m_Value(B)))) && - match(Op1, m_And(m_Not(m_Specific(A)), m_Specific(B)))) - return BinaryOperator::CreateXor(A, B); - - // (~A & B) ^ (A & ~B) -> A ^ B - if (match(Op0, m_And(m_Not(m_Value(A)), m_Value(B))) && - match(Op1, m_And(m_Specific(A), m_Not(m_Specific(B))))) { - return BinaryOperator::CreateXor(A, B); - } // (A ^ C)^(A | B) -> ((~A) & B) ^ C if (match(Op0, m_Xor(m_Value(D), m_Value(C))) && match(Op1, m_Or(m_Value(A), m_Value(B)))) { |
