[PowerPC] Disable float128 on AIX in Clang (#67298)

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

---------

Co-authored-by: Kai Luo <[email protected]>

Author: ecnelises

clang/lib/Basic/Targets/PPC.cpp

@@ -53,7 +53,7 @@ bool PPCTargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
     } else if (Feature == "+htm") {
       HasHTM = true;
     } else if (Feature == "+float128") {
-      HasFloat128 = true;
+      HasFloat128 = !getTriple().isOSAIX();
     } else if (Feature == "+power9-vector") {
       HasP9Vector = true;
     } else if (Feature == "+power10-vector") {

clang/test/Sema/128bitfloat.cpp

@@ -1,6 +1,7 @@
 // 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