[llvm] r247061 - refactor matches for De Morgan's Laws; NFCI

[David Majnemer via llvm-commits]

On Wed, Sep 9, 2015 at 2:00 PM, Sanjay Patel <spatel at rotateright.com> wrote:

> Sorry, I'm not understanding. Are you referring to the opcode selection of
> 'and' / 'or' before calling CreateBinOp()? That's a result of hoisting the
> code so it can be called from visitAnd / visitOr, and I added the assert to
> make sure this helper wouldn't be misused. Let me know if there's a hole in
> that logic.
>
>
This change is fine, sorry about that.  My mail client didn't render the
commit correctly :/


>
> On Wed, Sep 9, 2015 at 2:27 PM, David Majnemer <david.majnemer at gmail.com>
> wrote:
>
>>
>>
>> On Tue, Sep 8, 2015 at 1:14 PM, Sanjay Patel via llvm-commits <
>> llvm-commits at lists.llvm.org> wrote:
>>
>>> Author: spatel
>>> Date: Tue Sep  8 15:14:13 2015
>>> New Revision: 247061
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=247061&view=rev
>>> Log:
>>> refactor matches for De Morgan's Laws; NFCI
>>>
>>> Modified:
>>>     llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
>>>
>>> Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=247061&r1=247060&r2=247061&view=diff
>>>
>>> ==============================================================================
>>> --- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
>>> (original)
>>> +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Tue
>>> Sep  8 15:14:13 2015
>>> @@ -1200,6 +1200,34 @@ Value *InstCombiner::FoldAndOfFCmps(FCmp
>>>    return nullptr;
>>>  }
>>>
>>> +/// Match De Morgan's Laws:
>>> +/// (~A & ~B) == (~(A | B))
>>> +/// (~A | ~B) == (~(A & B))
>>> +static Instruction *matchDeMorgansLaws(BinaryOperator &I,
>>> +                                       InstCombiner::BuilderTy
>>> *Builder) {
>>> +  auto Opcode = I.getOpcode();
>>> +  assert((Opcode == Instruction::And || Opcode == Instruction::Or) &&
>>> +         "Trying to match De Morgan's Laws with something other than
>>> and/or");
>>> +
>>> +  Value *Op0 = I.getOperand(0);
>>> +  Value *Op1 = I.getOperand(1);
>>> +  // TODO: Use pattern matchers instead of dyn_cast.
>>> +  if (Value *Op0NotVal = dyn_castNotVal(Op0))
>>> +    if (Value *Op1NotVal = dyn_castNotVal(Op1))
>>> +      if (Op0->hasOneUse() && Op1->hasOneUse()) {
>>> +        // Flip the logic operation.
>>> +        if (Opcode == Instruction::And)
>>> +          Opcode = Instruction::Or;
>>> +        else
>>> +          Opcode = Instruction::And;
>>>
>>
>> Excuse me but how is this "no functional change" ?  I don't believe we
>> had the logic to conditional create an Or before.
>>
>>
>>> +        Value *LogicOp = Builder->CreateBinOp(Opcode, Op0NotVal,
>>> Op1NotVal,
>>> +                                              I.getName() +
>>> ".demorgan");
>>> +        return BinaryOperator::CreateNot(LogicOp);
>>> +      }
>>> +
>>> +  return nullptr;
>>> +}
>>> +
>>>  Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
>>>    bool Changed = SimplifyAssociativeOrCommutative(I);
>>>    Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
>>> @@ -1330,15 +1358,8 @@ Instruction *InstCombiner::visitAnd(Bina
>>>          return NV;
>>>    }
>>>
>>> -
>>> -  // (~A & ~B) == (~(A | B)) - De Morgan's Law
>>> -  if (Value *Op0NotVal = dyn_castNotVal(Op0))
>>> -    if (Value *Op1NotVal = dyn_castNotVal(Op1))
>>> -      if (Op0->hasOneUse() && Op1->hasOneUse()) {
>>> -        Value *Or = Builder->CreateOr(Op0NotVal, Op1NotVal,
>>> -                                      I.getName()+".demorgan");
>>> -        return BinaryOperator::CreateNot(Or);
>>> -      }
>>> +  if (Instruction *DeMorgan = matchDeMorgansLaws(I, Builder))
>>> +    return DeMorgan;
>>>
>>>    {
>>>      Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
>>> @@ -2360,14 +2381,8 @@ Instruction *InstCombiner::visitOr(Binar
>>>    if (match(Op0, m_And(m_Or(m_Specific(Op1), m_Value(C)), m_Value(A))))
>>>      return BinaryOperator::CreateOr(Op1, Builder->CreateAnd(A, C));
>>>
>>> -  // (~A | ~B) == (~(A & B)) - De Morgan's Law
>>> -  if (Value *Op0NotVal = dyn_castNotVal(Op0))
>>> -    if (Value *Op1NotVal = dyn_castNotVal(Op1))
>>> -      if (Op0->hasOneUse() && Op1->hasOneUse()) {
>>> -        Value *And = Builder->CreateAnd(Op0NotVal, Op1NotVal,
>>> -                                        I.getName()+".demorgan");
>>> -        return BinaryOperator::CreateNot(And);
>>> -      }
>>> +  if (Instruction *DeMorgan = matchDeMorgansLaws(I, Builder))
>>> +    return DeMorgan;
>>>
>>>    // Canonicalize xor to the RHS.
>>>    bool SwappedForXor = false;
>>>
>>>
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>>>
>>
>>
>
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