[clang] [clang] improve consistency with GCC vector comparison (PR #148954)

[Imple Lee via cfe-commits]

================
@@ -12901,24 +12901,24 @@ QualType Sema::GetSignedVectorType(QualType V) {
     return Context.getExtVectorType(Context.LongLongTy, VTy->getNumElements());
   }
 
-  if (TypeSize == Context.getTypeSize(Context.Int128Ty))
-    return Context.getVectorType(Context.Int128Ty, VTy->getNumElements(),
-                                 VectorKind::Generic);
-  if (TypeSize == Context.getTypeSize(Context.LongLongTy))
-    return Context.getVectorType(Context.LongLongTy, VTy->getNumElements(),
-                                 VectorKind::Generic);
-  if (TypeSize == Context.getTypeSize(Context.LongTy))
-    return Context.getVectorType(Context.LongTy, VTy->getNumElements(),
-                                 VectorKind::Generic);
   if (TypeSize == Context.getTypeSize(Context.IntTy))
     return Context.getVectorType(Context.IntTy, VTy->getNumElements(),
                                  VectorKind::Generic);
+  if (TypeSize == Context.getTypeSize(Context.SignedCharTy))
----------------
ImpleLee wrote:

Maybe a better option is to communicate with GCC developers to decide a not-so-awkward (and also backward-compatible and explicit) rule.

https://github.com/llvm/llvm-project/pull/148954