[llvm] [PowerPC][AIX] Emit PowerPC version for XCOFF (PR #95510)

[via llvm-commits]

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@@ -517,6 +517,11 @@ bool AsmPrinter::doInitialization(Module &M) {
   // On AIX, emit bytes for llvm.commandline metadata after .file so that the
   // C_INFO symbol is preserved if any csect is kept by the linker.
   if (TM.getTargetTriple().isOSBinFormatXCOFF()) {
+    // Emit .machine directive on AIX.
+    StringRef TargetCPU =
+        TM.getTargetCPU().empty() ? "pwr7" : TM.getTargetCPU();
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EsmeYi wrote:

> Yeah, "target-cpu" is something we ideally should be handling here, but I think there are some he tricky parts to this. "target-cpu" is a function level attribute and we are emitting a module level attribute. To do this right, we'd need to know the newest level we saw in the whole module (there definitely could be a mix, for example if we got LTO involved).

Thanks, currently I walk through the "target-cpu" attribute in all functions, map these values to `CFileCpuId` enum defined in header and set the newest level as the final target CPU level.

> Then it's also possible that we have no "target-cpu" attr (since I don't believe frontends are required to emit it) and and  TM.getTargetCPU().empty().

For this case, I use `any` as default value, which is for consistency with system `as` on AIX.

https://github.com/llvm/llvm-project/pull/95510