[Sema] Allow conversion between long double and __float128.

We should only ban this if long double is a double double. x86's 80 bit
long double is fine and supported by the backend.

llvm-svn: 322779

1 files changed, 5 insertions, 6 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index d7490b68a6f..23b3a0ccebf 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -1092,13 +1092,12 @@ static bool unsupportedTypeConversion(const Sema &S, QualType LHSType,
   Float128AndLongDouble |= (LHSElemType == S.Context.LongDoubleTy &&
                             RHSElemType == S.Context.Float128Ty);
 
-  /* We've handled the situation where __float128 and long double have the same
-     representation. The only other allowable conversion is if long double is
-     really just double.
-  */
+  // We've handled the situation where __float128 and long double have the same
+  // representation. We allow all conversions for all possible long double types
+  // except PPC's double double.
   return Float128AndLongDouble &&
-    (&S.Context.getFloatTypeSemantics(S.Context.LongDoubleTy) !=
-     &llvm::APFloat::IEEEdouble());
+    (&S.Context.getFloatTypeSemantics(S.Context.LongDoubleTy) ==
+     &llvm::APFloat::PPCDoubleDouble());
 }
 
 typedef ExprResult PerformCastFn(Sema &S, Expr *operand, QualType toType);