[clang] [PowerPC] Support local-dynamic TLS relocation on AIX (PR #66316)

[Amy Kwan via cfe-commits]

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@@ -145,9 +160,92 @@ namespace {
                                                               .addImm(0);
 
         if (IsAIX) {
-          // The variable offset and region handle are copied in r4 and r3. The
-          // copies are followed by GETtlsADDR32AIX/GETtlsADDR64AIX.
-          if (!IsTLSTPRelMI) {
+          if (MI.getOpcode() == PPC::TLSLDAIX8 ||
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amy-kwan wrote:

We're checking is the opcode is `PPC::TLSLDAIX`/`PPC::TLSLDAIX8` quite a bit. Maybe we should save this check into a boolean, similar to `IsTLSTPRelMI`.

https://github.com/llvm/llvm-project/pull/66316