[llvm] [Codegen][Backend] Remove redundant pseudo mov instruction (PR #139716)

[Matt Arsenault via llvm-commits]

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@@ -186,11 +186,13 @@ static bool isCandidate(const MachineInstr *MI, Register &DefedReg,
   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
     const MachineOperand &MO = MI->getOperand(i);
     if (MO.isReg()) {
-      if (MO.isDef()) {
+      if (MO.isDef() && DefedReg == MCRegister::NoRegister) {
         if (i == 0 && !MO.isImplicit() && !MO.isDead())
           DefedReg = MO.getReg();
         else
           return false;
+      } else if (MI->isPseudo() && MI->isMoveImmediate()) {
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arsenm wrote:

isPseudo does not give you any semantic information, you cannot use it here 

https://github.com/llvm/llvm-project/pull/139716