[clang] [llvm] [PowerPC] add TargetParser for PPC target (PR #97541)

[David Tenty via cfe-commits]

================
@@ -1963,8 +1964,11 @@ void Clang::AddPPCTargetArgs(const ArgList &Args,
   const llvm::Triple &T = getToolChain().getTriple();
   if (Args.getLastArg(options::OPT_mtune_EQ)) {
     CmdArgs.push_back("-tune-cpu");
-    std::string CPU = ppc::getPPCTuneCPU(Args, T);
-    CmdArgs.push_back(Args.MakeArgString(CPU));
+    StringRef CPU = "";
+    if (Arg *A = Args.getLastArg(clang::driver::options::OPT_mtune_EQ))
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daltenty wrote:

nit: You can get just do this assignment in the outer if condition, to avoid calling `Args.getLastArg` twice with the exact same arguments. Then just check the result here:
```suggestion
    if (A)
```

https://github.com/llvm/llvm-project/pull/97541