[llvm] [AMDGPU][NFC] Refactor SCC optimization (PR #165871)

[Matt Arsenault via llvm-commits]

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@@ -10618,6 +10618,42 @@ bool SIInstrInfo::analyzeCompare(const MachineInstr &MI, Register &SrcReg,
   return false;
 }
 
+// SCC is already valid after SCCValid.
+// SCCRedefine will redefine SCC to the same value already available after
+// SCCValid. If there are no intervening SCC conflicts delete SCCRedefine and
+// update kill/dead flags if necessary.
+static bool optimizeSCC(MachineInstr *SCCValid, MachineInstr *SCCRedefine,
+                        const SIRegisterInfo *RI) {
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arsenm wrote:

```suggestion
                        const SIRegisterInfo &RI) {
```

https://github.com/llvm/llvm-project/pull/165871