[PowerPC] Disable float128 on AIX in Clang

[qiucf]

Summary

PowerPC AIX backend does not support float128 at all. Diagnose even when specifying -mfloat128 to avoid backend crash.

[qiucf]

Migrated to https://github.com/llvm/llvm-project/pull/67298

clang/lib/Basic/Targets/PPC.cpp

for (const auto &Feature : Features) {
     } else if (Feature == "+power8-vector") {
       HasP8Vector = true;
     } else if (Feature == "+crypto") {
       HasP8Crypto = true;
     } else if (Feature == "+direct-move") {
       HasDirectMove = true;
     } else if (Feature == "+htm") {
       HasHTM = true;
-    } else if (Feature == "+float128") {
+    } else if (Feature == "+float128" && !getTriple().isOSAIX()) {
       HasFloat128 = true;
     } else if (Feature == "+power9-vector") {
       HasP9Vector = true;
     } else if (Feature == "+power10-vector") {
       HasP10Vector = true;
     } else if (Feature == "+pcrelative-memops") {
       HasPCRelativeMemops = true;
     } else if (Feature == "+prefix-instrs") {

clang/test/Sema/128bitfloat.cpp

 // RUN: %clang_cc1 -verify -std=gnu++11 %s
 // RUN: %clang_cc1 -verify -std=c++11 %s
 // RUN: %clang_cc1 -triple powerpc64-linux -verify -std=c++11 %s
+// RUN: %clang_cc1 -triple powerpc64-ibm-aix -target-feature +float128 -verify -std=c++11 %s
 // RUN: %clang_cc1 -triple i686-windows-gnu -verify -std=c++11 %s
 // RUN: %clang_cc1 -triple x86_64-windows-gnu -verify -std=c++11 %s
 // RUN: %clang_cc1 -triple x86_64-windows-msvc -verify -std=c++11 %s
 
 #if defined(__FLOAT128__) || defined(__SIZEOF_FLOAT128__)
 
 #if defined(__powerpc__)
 template <typename> struct __is_float128 { static constexpr bool value = false; };