[Clang] Fix long double availability check

[qiucf]

Summary

fae0dfa changed code to check 128-bit float availability, since it introduced a new 128-bit double type on PowerPC. However, there're other long float types besides IEEE float128 and PPC double-double requiring this feature. This patch fixes it.

[ronlieb]

thank you for the fix.

clang/lib/Sema/Sema.cpp

if (Ty->isExtIntType()) {
       return;
     }
 
     // Check if we are dealing with two 'long double' but with different
     // semantics.
     bool LongDoubleMismatched = false;
     if (Ty->isRealFloatingType() && Context.getTypeSize(Ty) == 128) {
       const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(Ty);
-      if (!Ty->isIbm128Type() && !Ty->isFloat128Type() &&
-          &Sem != &Context.getTargetInfo().getLongDoubleFormat())
+      if ((&Sem != &llvm::APFloat::PPCDoubleDouble() &&
+           !Context.getTargetInfo().hasFloat128Type()) ||
+          (&Sem == &llvm::APFloat::PPCDoubleDouble() &&
+           !Context.getTargetInfo().hasIbm128Type()))
         LongDoubleMismatched = true;
     }
 
     if ((Ty->isFloat16Type() && !Context.getTargetInfo().hasFloat16Type()) ||
         (Ty->isFloat128Type() && !Context.getTargetInfo().hasFloat128Type()) ||
         (Ty->isIbm128Type() && !Context.getTargetInfo().hasIbm128Type()) ||
         (Ty->isIntegerType() && Context.getTypeSize(Ty) == 128 &&
          !Context.getTargetInfo().hasInt128Type()) ||

clang/test/OpenMP/amdgcn_ldbl_check.cpp

+// REQUIRES: amdgpu-registered-target
+
+// RUN: %clang_cc1 -triple x86_64-mingw64 -emit-llvm-bc -target-cpu x86-64 -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -o %t.bc -x c++ %s
+// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -aux-triple x86_64-mingw64 -fsyntax-only -target-cpu gfx900 -fopenmp -fopenmp-is-device -fopenmp-host-ir-file-path %t.bc -x c++ %s
+// expected-no-diagnostics
+
+void print(double);
+
+constexpr double operator"" _X (long double a)
+{
+  return (double)a;
+}
+
+int main()
+{
+  auto a = 1._X;
+  print(a);
+#pragma omp target map(tofrom: a)
+  {
+#pragma omp teams num_teams(1) thread_limit(4)
+    {
+      a += 1._X;
+    }
+  }
+  print(a);
+  return 0;
+}