Add -fnative-half-arguments-and-returns

Summary:
r246764 handled __fp16 arguments and returns for AAPCS, but skipped this
handling for OpenCL.  Simlar to OpenCL, RenderScript also handles __fp16
type natively.

This patch adds the -fnative-half-arguments-and-returns command line
flag to allow such languages to skip this coercion of __fp16.

Reviewers: srhines, olista01

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D18138

llvm-svn: 263795

clang/include/clang/Basic/LangOptions.def

@@ -163,6 +163,7 @@ LANGOPT(ShortEnums        , 1, 0, "short enum types")
 LANGOPT(OpenCL            , 1, 0, "OpenCL")
 LANGOPT(OpenCLVersion     , 32, 0, "OpenCL version")
 LANGOPT(NativeHalfType    , 1, 0, "Native half type support")
+LANGOPT(NativeHalfArgsAndReturns, 1, 0, "Native half args and returns")
 LANGOPT(HalfArgsAndReturns, 1, 0, "half args and returns")
 LANGOPT(CUDA              , 1, 0, "CUDA")
 LANGOPT(OpenMP            , 1, 0, "OpenMP support")

clang/include/clang/Driver/CC1Options.td

@@ -603,6 +603,8 @@ def fno_rtti_data : Flag<["-"], "fno-rtti-data">,
   HelpText<"Control emission of RTTI data">;
 def fnative_half_type: Flag<["-"], "fnative-half-type">,
   HelpText<"Use the native half type for __fp16 instead of promoting to float">;
+def fnative_half_arguments_and_returns : Flag<["-"], "fnative-half-arguments-and-returns">,
+  HelpText<"Use the native __fp16 type for arguments and returns (and skip ABI-specific lowering)">;
 def fallow_half_arguments_and_returns : Flag<["-"], "fallow-half-arguments-and-returns">,
   HelpText<"Allow function arguments and returns of type half">;
 

clang/lib/CodeGen/TargetInfo.cpp

@@ -5106,7 +5106,7 @@ ABIArgInfo ARMABIInfo::classifyArgumentType(QualType Ty,
   // __fp16 gets passed as if it were an int or float, but with the top 16 bits
   // unspecified. This is not done for OpenCL as it handles the half type
   // natively, and does not need to interwork with AAPCS code.
-  if (Ty->isHalfType() && !getContext().getLangOpts().OpenCL) {
+  if (Ty->isHalfType() && !getContext().getLangOpts().NativeHalfArgsAndReturns) {
     llvm::Type *ResType = IsEffectivelyAAPCS_VFP ?
       llvm::Type::getFloatTy(getVMContext()) :
       llvm::Type::getInt32Ty(getVMContext());
@@ -5298,7 +5298,7 @@ ABIArgInfo ARMABIInfo::classifyReturnType(QualType RetTy,
   // __fp16 gets returned as if it were an int or float, but with the top 16
   // bits unspecified. This is not done for OpenCL as it handles the half type
   // natively, and does not need to interwork with AAPCS code.
-  if (RetTy->isHalfType() && !getContext().getLangOpts().OpenCL) {
+  if (RetTy->isHalfType() && !getContext().getLangOpts().NativeHalfArgsAndReturns) {
     llvm::Type *ResType = IsEffectivelyAAPCS_VFP ?
       llvm::Type::getFloatTy(getVMContext()) :
       llvm::Type::getInt32Ty(getVMContext());

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1434,6 +1434,7 @@ void CompilerInvocation::setLangDefaults(LangOptions &Opts, InputKind IK,
     Opts.LaxVectorConversions = 0;
     Opts.DefaultFPContract = 1;
     Opts.NativeHalfType = 1;
+    Opts.NativeHalfArgsAndReturns = 1;
   }
 
   Opts.CUDA = IK == IK_CUDA || IK == IK_PreprocessedCuda ||
@@ -1795,7 +1796,11 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
   Opts.ModuleFeatures = Args.getAllArgValues(OPT_fmodule_feature);
   std::sort(Opts.ModuleFeatures.begin(), Opts.ModuleFeatures.end());
   Opts.NativeHalfType |= Args.hasArg(OPT_fnative_half_type);
-  Opts.HalfArgsAndReturns = Args.hasArg(OPT_fallow_half_arguments_and_returns);
+  Opts.NativeHalfArgsAndReturns |= Args.hasArg(OPT_fnative_half_arguments_and_returns);
+  // Enable HalfArgsAndReturns if present in Args or if NativeHalfArgsAndReturns
+  // is enabled.
+  Opts.HalfArgsAndReturns = Args.hasArg(OPT_fallow_half_arguments_and_returns)
+                            | Opts.NativeHalfArgsAndReturns;
   Opts.GNUAsm = !Args.hasArg(OPT_fno_gnu_inline_asm);
 
   // __declspec is enabled by default for the PS4 by the driver, and also

clang/test/CodeGen/arm-fp16-arguments.c

@@ -1,5 +1,6 @@
 // RUN: %clang_cc1 -triple armv7a--none-eabi -target-abi aapcs -mfloat-abi soft -fallow-half-arguments-and-returns -emit-llvm -o - -O1 %s | FileCheck %s --check-prefix=CHECK --check-prefix=SOFT
 // RUN: %clang_cc1 -triple armv7a--none-eabi -target-abi aapcs -mfloat-abi hard -fallow-half-arguments-and-returns -emit-llvm -o - -O1 %s | FileCheck %s --check-prefix=CHECK --check-prefix=HARD
+// RUN: %clang_cc1 -triple armv7a--none-eabi -target-abi aapcs -mfloat-abi soft -fnative-half-arguments-and-returns -emit-llvm -o - -O1 %s | FileCheck %s --check-prefix=NATIVE
 
 __fp16 g;
 
@@ -10,12 +11,17 @@ void t1(__fp16 a) { g = a; }
 // HARD: [[BITCAST:%.*]] = bitcast float [[PARAM]] to i32
 // HARD: [[TRUNC:%.*]] = trunc i32 [[BITCAST]] to i16
 // CHECK: store i16 [[TRUNC]], i16* bitcast (half* @g to i16*)
+// NATIVE: define void @t1(half [[PARAM:%.*]])
+// NATIVE: store half [[PARAM]], half* @g
 
 __fp16 t2() { return g; }
 // SOFT: define i32 @t2()
 // HARD: define arm_aapcs_vfpcc float @t2()
+// NATIVE: define half @t2()
 // CHECK: [[LOAD:%.*]] = load i16, i16* bitcast (half* @g to i16*)
 // CHECK: [[ZEXT:%.*]] = zext i16 [[LOAD]] to i32
 // SOFT: ret i32 [[ZEXT]]
 // HARD: [[BITCAST:%.*]] = bitcast i32 [[ZEXT]] to float
 // HARD: ret float [[BITCAST]]
+// NATIVE: [[LOAD:%.*]] = load half, half* @g
+// NATIVE: ret half [[LOAD]]