[llvm] [AMDGPU] Fix combineMasks dropping condition (PR #203180)

[Arseniy Obolenskiy via llvm-commits]

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@@ -602,22 +602,41 @@ void SILowerControlFlow::findMaskOperands(MachineInstr &MI, unsigned OpNo,
 // One of the operands is exec mask.
 void SILowerControlFlow::combineMasks(MachineInstr &MI) {
   assert(MI.getNumExplicitOperands() == 3);
-  SmallVector<MachineOperand, 4> Ops;
-  unsigned OpToReplace = 1;
-  findMaskOperands(MI, 1, Ops);
-  if (Ops.size() == 1) OpToReplace = 2; // First operand can be exec or its copy
-  findMaskOperands(MI, 2, Ops);
-  if (Ops.size() != 3) return;
-
-  unsigned UniqueOpndIdx;
-  if (Ops[0].isIdenticalTo(Ops[1])) UniqueOpndIdx = 2;
-  else if (Ops[0].isIdenticalTo(Ops[2])) UniqueOpndIdx = 1;
-  else if (Ops[1].isIdenticalTo(Ops[2])) UniqueOpndIdx = 1;
-  else return;
+  SmallVector<MachineOperand, 2> Src1, Src2;
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aobolensk wrote:

Done

https://github.com/llvm/llvm-project/pull/203180