3 files changed, 21 insertions, 17 deletions

diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp
index 80ab2ed28ce..4344f940459 100644
--- a/clang/lib/CodeGen/CGExprConstant.cpp
+++ b/clang/lib/CodeGen/CGExprConstant.cpp
@@ -1140,7 +1140,8 @@ llvm::Constant *CodeGenModule::EmitConstantValue(const APValue &Value,
   }
   case APValue::Float: {
     const llvm::APFloat &Init = Value.getFloat();
-    if (&Init.getSemantics() == &llvm::APFloat::IEEEhalf)
+    if (&Init.getSemantics() == &llvm::APFloat::IEEEhalf &&
+         !Context.getLangOpts().NativeHalfType)
       return llvm::ConstantInt::get(VMContext, Init.bitcastToAPInt());
     else
       return llvm::ConstantFP::get(VMContext, Init);
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index ed927e2fb4a..7f0eda89930 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -664,9 +664,8 @@ Value *ScalarExprEmitter::EmitScalarConversion(Value *Src, QualType SrcType,
   QualType OrigSrcType = SrcType;
   llvm::Type *SrcTy = Src->getType();
 
-  // Floating casts might be a bit special: if we're doing casts to / from half
-  // FP, we should go via special intrinsics.
-  if (SrcType->isHalfType()) {
+  // If casting to/from storage-only half FP, use special intrinsics.
+  if (SrcType->isHalfType() && !CGF.getContext().getLangOpts().NativeHalfType) {
     Src = Builder.CreateCall(CGF.CGM.getIntrinsic(llvm::Intrinsic::convert_from_fp16), Src);
     SrcType = CGF.getContext().FloatTy;
     SrcTy = CGF.FloatTy;
@@ -735,7 +734,7 @@ Value *ScalarExprEmitter::EmitScalarConversion(Value *Src, QualType SrcType,
                              DstTy);
 
   // Cast to half via float
-  if (DstType->isHalfType())
+  if (DstType->isHalfType() && !CGF.getContext().getLangOpts().NativeHalfType)
     DstTy = CGF.FloatTy;
 
   if (isa<llvm::IntegerType>(SrcTy)) {
@@ -1536,7 +1535,7 @@ ScalarExprEmitter::EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
     // Add the inc/dec to the real part.
     llvm::Value *amt;
 
-    if (type->isHalfType()) {
+    if (type->isHalfType() && !CGF.getContext().getLangOpts().NativeHalfType) {
       // Another special case: half FP increment should be done via float
       value =
     Builder.CreateCall(CGF.CGM.getIntrinsic(llvm::Intrinsic::convert_from_fp16),
@@ -1558,7 +1557,7 @@ ScalarExprEmitter::EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
     }
     value = Builder.CreateFAdd(value, amt, isInc ? "inc" : "dec");
 
-    if (type->isHalfType())
+    if (type->isHalfType() && !CGF.getContext().getLangOpts().NativeHalfType)
       value =
        Builder.CreateCall(CGF.CGM.getIntrinsic(llvm::Intrinsic::convert_to_fp16),
                           value);
diff --git a/clang/lib/CodeGen/CodeGenTypes.cpp b/clang/lib/CodeGen/CodeGenTypes.cpp
index c186ebff29c..e78cbabda84 100644
--- a/clang/lib/CodeGen/CodeGenTypes.cpp
+++ b/clang/lib/CodeGen/CodeGenTypes.cpp
@@ -263,9 +263,14 @@ void CodeGenTypes::UpdateCompletedType(const TagDecl *TD) {
 }
 
 static llvm::Type *getTypeForFormat(llvm::LLVMContext &VMContext,
-                                    const llvm::fltSemantics &format) {
-  if (&format == &llvm::APFloat::IEEEhalf)
-    return llvm::Type::getInt16Ty(VMContext);
+                                    const llvm::fltSemantics &format,
+                                    bool UseNativeHalf = false) {
+  if (&format == &llvm::APFloat::IEEEhalf) {
+    if (UseNativeHalf)
+      return llvm::Type::getHalfTy(VMContext);
+    else
+      return llvm::Type::getInt16Ty(VMContext);
+  }
   if (&format == &llvm::APFloat::IEEEsingle)
     return llvm::Type::getFloatTy(VMContext);
   if (&format == &llvm::APFloat::IEEEdouble)
@@ -344,18 +349,17 @@ llvm::Type *CodeGenTypes::ConvertType(QualType T) {
       break;
 
     case BuiltinType::Half:
-      // Half is special: it might be lowered to i16 (and will be storage-only
-      // type),. or can be represented as a set of native operations.
-
-      // FIXME: Ask target which kind of half FP it prefers (storage only vs
-      // native).
-      ResultType = llvm::Type::getInt16Ty(getLLVMContext());
+      // Half FP can either be storage-only (lowered to i16) or native.
+      ResultType = getTypeForFormat(getLLVMContext(),
+          Context.getFloatTypeSemantics(T),
+          Context.getLangOpts().NativeHalfType);
       break;
     case BuiltinType::Float:
     case BuiltinType::Double:
     case BuiltinType::LongDouble:
       ResultType = getTypeForFormat(getLLVMContext(),
-                                    Context.getFloatTypeSemantics(T));
+                                    Context.getFloatTypeSemantics(T),
+                                    /* UseNativeHalf = */ false);
       break;
 
     case BuiltinType::NullPtr: