[llvm] [AMDGPU] Recognise bitmask operations as srcmods (PR #149110)

[Janek van Oirschot via llvm-commits]

================
@@ -3036,6 +3036,36 @@ bool AMDGPUDAGToDAGISel::SelectVOP3ModsImpl(SDValue In, SDValue &Src,
     Src = Src.getOperand(0);
   }
 
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JanekvO wrote:

Can probably guard on the common parts of  the if-nests here
i.e.,
```

if (!isBitwiseAndOrXor(Src->getOpcode()) || Src.getValueType().getFixedSizeInBits() == 16) // Alternatively, check here if Src has 2 operands and check for and/or/xor later
  return true;
ConstantSDNode *CRHS = dyn_cast<ConstantSDNode>(Src->getOperand(1)); // Still have to check whether CRHS exists
```

https://github.com/llvm/llvm-project/pull/149110