[OpenCL] Allow half type kernel argument when cl_khr_fp16 is enabled

[bader]

test/SemaOpenCL/half.cl

29

It's not related to your change, but it looks like there are two checks that report the same error.
Could you remove the duplication, please?

[yaxunl]

Remove redundant diagnostic msg.

[bader]

lib/Sema/SemaDecl.cpp

7599–7602

It looks strange to me. First we check if parameter type is half - we set InvalidKernelParam status, later we check again and do not report an error.
I think it would be simpler just return ValidKernelParam for half data type from getOpenCLKernelParameterType,

I think the whole patch should two deleted lines from getOpenCLKernelParameterType function + test case.

[yaxunl]

lib/Sema/SemaDecl.cpp

7599–7602

getOpenCLKernelParameterType should report half type as InvalidKernelParam since it really is an invalid kernel argument type. We do not emit diagnostic msg because the msg is redundant, not because half type is a valid kernel argument type.

getOpenCLKernelParameterType may be used for other purpose. Reporting half type as a valid kernel argument violates the semantics of getOpenCLKernelParameterType and can cause confusion and potential error.

[Anastasia]

lib/Sema/SemaDecl.cpp

7600

-> elsewhere

[bader]

lib/Sema/SemaDecl.cpp

7599–7602

Maybe we should the other way.
Leave half parameter check here only and remove duplicate check that reports "declaring function parameter of type 'half' is not allowed; did you forget * ?" message.

[yaxunl]

lib/Sema/SemaDecl.cpp

7599–7602

Clang can emit two error msgs in this case since it does two independent checks:

1. half type cannot be used as function argument when cl_khr_fp16 is disabled

2. half type cannot be used as kernel function argument when cl_khr_fp16 is disabled

I think error msg 1 is better than error msg 2 since error msg 1 provides more information, i.e., when cl_khr_fp16 is disabled, half type cannot be used as either kernel function argument or non-kernel function argument, whereas error msg 2 may give user the wrong impression that half type can not be used for kernel function argument only.

[yaxunl]

lib/Sema/SemaDecl.cpp

7600

I will fix it in commit.

lib/Sema/SemaDecl.cpp

   ValidKernelParam,
   PtrPtrKernelParam,
   PtrKernelParam,
   PrivatePtrKernelParam,
   InvalidKernelParam,
   RecordKernelParam
 };
 
-static OpenCLParamType getOpenCLKernelParameterType(QualType PT) {
+static OpenCLParamType getOpenCLKernelParameterType(Sema &S, QualType PT) {
   if (PT->isPointerType()) {
     QualType PointeeType = PT->getPointeeType();
     if (PointeeType->isPointerType())
       return PtrPtrKernelParam;
     return PointeeType.getAddressSpace() == 0 ? PrivatePtrKernelParam
                                               : PtrKernelParam;
   }
 
   // TODO: Forbid the other integer types (size_t, ptrdiff_t...) when they can
   // be used as builtin types.
 
   if (PT->isImageType())
     return PtrKernelParam;
 
   if (PT->isBooleanType())
     return InvalidKernelParam;
 
   if (PT->isEventT())
     return InvalidKernelParam;
 
-  if (PT->isHalfType())
+  // OpenCL extension spec v1.2 s9.5:
+  // This extension adds support for half scalar and vector types as built-in
+  // types that can be used for arithmetic operations, conversions etc.
+  if (!S.getOpenCLOptions().cl_khr_fp16 && PT->isHalfType())
     return InvalidKernelParam;
 
   if (PT->isRecordType())
     return RecordKernelParam;
 
   return ValidKernelParam;
 }
 
 static void checkIsValidOpenCLKernelParameter(
   Sema &S,
   Declarator &D,
   ParmVarDecl *Param,
   llvm::SmallPtrSetImpl<const Type *> &ValidTypes) {
   QualType PT = Param->getType();
 
   // Cache the valid types we encounter to avoid rechecking structs that are
   // used again
   if (ValidTypes.count(PT.getTypePtr()))
     return;
 
-  switch (getOpenCLKernelParameterType(PT)) {
+  switch (getOpenCLKernelParameterType(S, PT)) {
   case PtrPtrKernelParam:
     // OpenCL v1.2 s6.9.a:
     // A kernel function argument cannot be declared as a
     // pointer to a pointer type.
     S.Diag(Param->getLocation(), diag::err_opencl_ptrptr_kernel_param);
     D.setInvalidType();
     return;
 

     // built-in scalar types bool, half, size_t, ptrdiff_t, intptr_t, and
     // uintptr_t or a struct and/or union that contain fields declared to be
     // one of these built-in scalar types.
 
   case InvalidKernelParam:
     // OpenCL v1.2 s6.8 n:
     // A kernel function argument cannot be declared
     // of event_t type.
-    S.Diag(Param->getLocation(), diag::err_bad_kernel_param_type) << PT;
+    // Do not diagnose half type since it is diagnosed as invalid argument
+    // type for any function eleswhere.
+    if (!PT->isHalfType())
+      S.Diag(Param->getLocation(), diag::err_bad_kernel_param_type) << PT;
     D.setInvalidType();
     return;
 
   case PtrKernelParam:
   case ValidKernelParam:
     ValidTypes.insert(PT.getTypePtr());
     return;
 

     VisitStack.push_back(nullptr);
 
     for (const auto *FD : RD->fields()) {
       QualType QT = FD->getType();
 
       if (ValidTypes.count(QT.getTypePtr()))
         continue;
 
-      OpenCLParamType ParamType = getOpenCLKernelParameterType(QT);
+      OpenCLParamType ParamType = getOpenCLKernelParameterType(S, QT);
       if (ParamType == ValidKernelParam)
         continue;
 
       if (ParamType == RecordKernelParam) {
         VisitStack.push_back(FD);
         continue;
       }
 

test/SemaOpenCL/half.cl

half half_disabled(half *p, // expected-error{{declaring function return value of type 'half' is not allowed}}
 
   half *allowed = &p[1];
   half *allowed2 = &*p;
   half *allowed3 = p + 1;
 
   return h;
 }
 
+kernel void half_disabled_kernel(global half *p,
+                                 half h);  // expected-error{{declaring function parameter of type 'half' is not allowed; did you forget * ?}}
+
 // Exactly the same as above but with the cl_khr_fp16 extension enabled.
 #pragma OPENCL EXTENSION cl_khr_fp16 : enable
 constant half a = 1.0h;
 half half_enabled(half *p, half h)
 {
   half a[2];
   half b;
   *p;
   *p = 0;
   p[1];
   p[1] = 0;
 
   float c = 1.0f;
   b = (half) c;
   c = (float) 1.0h;
   b = 1.0h;
 
   half *allowed = &p[1];
   half *allowed2 = &*p;
   half *allowed3 = p + 1;
 
   return h;
 }
+
+kernel void half_enabled_kernel(global half *p,
+                                half h);
+

test/SemaOpenCL/invalid-kernel-parameters.cl

 // RUN: %clang_cc1 -fsyntax-only -verify %s -triple spir-unknown-unknown
 
+kernel void half_arg(half x) { } // expected-error{{declaring function parameter of type 'half' is not allowed; did you forget * ?}}
+
 #pragma OPENCL EXTENSION cl_khr_fp16 : enable
 
 
 // Disallowed: parameters with type
 // bool, half, size_t, ptrdiff_t, intptr_t, and uintptr_t
 // or a struct / union with any of these types in them
 
 // TODO: Ban int types, size_t, ptrdiff_t ...
 
 kernel void bool_arg(bool x) { } // expected-error{{'bool' cannot be used as the type of a kernel parameter}}
 
-kernel void half_arg(half x) { } // expected-error{{'half' cannot be used as the type of a kernel parameter}}
+// half kernel argument is allowed when cl_khr_fp16 is enabled.
+kernel void half_arg(half x) { }
 
 typedef struct ContainsBool // expected-note{{within field of type 'ContainsBool' declared here}}
 {
   bool x; // expected-note{{field of illegal type 'bool' declared here}}
 } ContainsBool;
 
 kernel void bool_in_struct_arg(ContainsBool x) { } // expected-error{{'ContainsBool' (aka 'struct ContainsBool') cannot be used as the type of a kernel parameter}}