[clang] [llvm] [PowerPC] Tune AIX shared library TLS model at function level (PR #84132)

[Kai Luo via cfe-commits]

================
@@ -80,6 +80,7 @@ class LLVM_LIBRARY_VISIBILITY PPCTargetInfo : public TargetInfo {
   bool IsISA3_0 = false;
   bool IsISA3_1 = false;
   bool HasQuadwordAtomics = false;
+  bool HasAIXShLibTLSModelHeuristic = false;
----------------
bzEq wrote:

Code in `PPCTargetLowering::LowerGlobalTLSAddressAIX` like
```
Subtarget.hasAIXSmallLocalExecTLS()
```
which is generated in `PPCGenSubtargetInfo.inc`, whose value is initialized by feature string `aix-small-local-exec-tls` in LLVM IR rather than the variable defined in clang.

https://github.com/llvm/llvm-project/pull/84132