1 files changed, 66 insertions, 3 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 66b87120b0d..a5ee8bebae7 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -1155,6 +1155,48 @@ static QualType handleFloatConversion(Sema &S, ExprResult &LHS,
                                     /*convertFloat=*/!IsCompAssign);
 }
 
+/// \brief Diagnose attempts to convert between __float128 and long double if
+/// there is no support for such conversion. Helper function of
+/// UsualArithmeticConversions().
+static bool unsupportedTypeConversion(const Sema &S, QualType LHSType,
+                                      QualType RHSType) {
+  /*  No issue converting if at least one of the types is not a floating point
+      type or the two types have the same rank.
+  */
+  if (!LHSType->isFloatingType() || !RHSType->isFloatingType() ||
+      S.Context.getFloatingTypeOrder(LHSType, RHSType) == 0)
+    return false;
+
+  assert(LHSType->isFloatingType() && RHSType->isFloatingType() &&
+         "The remaining types must be floating point types.");
+
+  auto *LHSComplex = LHSType->getAs<ComplexType>();
+  auto *RHSComplex = RHSType->getAs<ComplexType>();
+
+  QualType LHSElemType = LHSComplex ?
+    LHSComplex->getElementType() : LHSType;
+  QualType RHSElemType = RHSComplex ?
+    RHSComplex->getElementType() : RHSType;
+
+  // No issue if the two types have the same representation
+  if (&S.Context.getFloatTypeSemantics(LHSElemType) ==
+      &S.Context.getFloatTypeSemantics(RHSElemType))
+    return false;
+
+  bool Float128AndLongDouble = (LHSElemType == S.Context.Float128Ty &&
+                                RHSElemType == S.Context.LongDoubleTy);
+  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.
+  */
+  return Float128AndLongDouble &&
+    (&S.Context.getFloatTypeSemantics(S.Context.LongDoubleTy) !=
+     &llvm::APFloat::IEEEdouble);
+}
+
 typedef ExprResult PerformCastFn(Sema &S, Expr *operand, QualType toType);
 
 namespace {
@@ -1318,6 +1360,11 @@ QualType Sema::UsualArithmeticConversions(ExprResult &LHS, ExprResult &RHS,
 
   // At this point, we have two different arithmetic types.
 
+  // Diagnose attempts to convert between __float128 and long double where
+  // such conversions currently can't be handled.
+  if (unsupportedTypeConversion(*this, LHSType, RHSType))
+    return QualType();
+
   // Handle complex types first (C99 6.3.1.8p1).
   if (LHSType->isComplexType() || RHSType->isComplexType())
     return handleComplexFloatConversion(*this, LHS, RHS, LHSType, RHSType,
@@ -3327,10 +3374,12 @@ ExprResult Sema::ActOnNumericConstant(const Token &Tok, Scope *UDLScope) {
       }
     } else if (Literal.isFloat)
       Ty = Context.FloatTy;
-    else if (!Literal.isLong)
-      Ty = Context.DoubleTy;
-    else
+    else if (Literal.isLong)
       Ty = Context.LongDoubleTy;
+    else if (Literal.isFloat128)
+      Ty = Context.Float128Ty;
+    else
+      Ty = Context.DoubleTy;
 
     Res = BuildFloatingLiteral(*this, Literal, Ty, Tok.getLocation());
 
@@ -6604,6 +6653,15 @@ QualType Sema::CheckConditionalOperands(ExprResult &Cond, ExprResult &LHS,
   QualType LHSTy = LHS.get()->getType();
   QualType RHSTy = RHS.get()->getType();
 
+  // Diagnose attempts to convert between __float128 and long double where
+  // such conversions currently can't be handled.
+  if (unsupportedTypeConversion(*this, LHSTy, RHSTy)) {
+    Diag(QuestionLoc,
+         diag::err_typecheck_cond_incompatible_operands) << LHSTy << RHSTy
+      << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
+    return QualType();
+  }
+
   // OpenCL v2.0 s6.12.5 - Blocks cannot be used as expressions of the ternary
   // selection operator (?:).
   if (getLangOpts().OpenCL &&
@@ -7337,6 +7395,11 @@ Sema::CheckAssignmentConstraints(QualType LHSType, ExprResult &RHS,
     return Incompatible;
   }
 
+  // Diagnose attempts to convert between __float128 and long double where
+  // such conversions currently can't be handled.
+  if (unsupportedTypeConversion(*this, LHSType, RHSType))
+    return Incompatible;
+
   // Arithmetic conversions.
   if (LHSType->isArithmeticType() && RHSType->isArithmeticType() &&
       !(getLangOpts().CPlusPlus && LHSType->isEnumeralType())) {