[llvm] [PowerPC] Fix ppc-reduce-cr-ops mishandling of subregister uses (PR #144405)

[Nemanja Ivanovic via llvm-commits]

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@@ -471,6 +474,8 @@ PPCReduceCRLogicals::createCRLogicalOpInfo(MachineInstr &MIParam) {
   } else {
     MachineInstr *Def1 = lookThroughCRCopy(MIParam.getOperand(1).getReg(),
                                            Ret.SubregDef1, Ret.CopyDefs.first);
+    if (Ret.SubregDef1 == 0)
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nemanjai wrote:

If the handling for `Subreg` is removed from `lookThroughCRCopy()`, this condition and the one on line 489 can just go away and the assignments to `Ret.SubregDef1` and `Ret.SubregDef2` can be unconditional.

https://github.com/llvm/llvm-project/pull/144405