[OpenCL] Change extension handling for -fdeclare-opencl-builtins

Until now, the `-fdeclare-opencl-builtins` option behaved differently compared to inclusion of `opencl-c.h`: builtins that are part of an extension were only available if the extension was enabled using the corresponding pragma. Builtins that belong to an extension are guarded using a preprocessor macro (that is named after the extension) in `opencl-c.h`. Align the behaviour of `-fdeclare-opencl-builtins` with this. Co-authored-by: Anastasia Stulova Differential Revision: https://reviews.llvm.org/D95616

Author: svenvh

clang/lib/Sema/SemaLookup.cpp

@@ -743,18 +743,6 @@ static void GetOpenCLBuiltinFctOverloads(
  }
 }
 
-/// Add extensions to the function declaration.
-/// \param S (in/out) The Sema instance.
-/// \param BIDecl (in) Description of the builtin.
-/// \param FDecl (in/out) FunctionDecl instance.
-static void AddOpenCLExtensions(Sema &S, const OpenCLBuiltinStruct &BIDecl,
- FunctionDecl *FDecl) {
- // Fetch extension associated with a function prototype.
- StringRef E = FunctionExtensionTable[BIDecl.Extension];
- if (E != "")
- S.setOpenCLExtensionForDecl(FDecl, E);
-}
-
 /// When trying to resolve a function name, if isOpenCLBuiltin() returns a
 /// non-null <Index, Len> pair, then the name is referencing an OpenCL
 /// builtin function. Add all candidate signatures to the LookUpResult.
@@ -790,6 +778,13 @@ static void InsertOCLBuiltinDeclarationsFromTable(Sema &S, LookupResult &LR,
  (OpenCLVersion >= OpenCLBuiltin.MaxVersion))
  continue;
 
+ // Ignore this builtin function if it carries an extension macro that is
+ // not defined. This indicates that the extension is not supported by the
+ // target, so the builtin function should not be available.
+ StringRef Ext = FunctionExtensionTable[OpenCLBuiltin.Extension];
+ if (!Ext.empty() && !S.getPreprocessor().isMacroDefined(Ext))
+ continue;
+
  SmallVector<QualType, 1> RetTypes;
  SmallVector<SmallVector<QualType, 1>, 5> ArgTypes;
 
@@ -843,8 +838,6 @@ static void InsertOCLBuiltinDeclarationsFromTable(Sema &S, LookupResult &LR,
  if (!S.getLangOpts().OpenCLCPlusPlus)
  NewOpenCLBuiltin->addAttr(OverloadableAttr::CreateImplicit(Context));
 
- AddOpenCLExtensions(S, OpenCLBuiltin, NewOpenCLBuiltin);
-
  LR.addDecl(NewOpenCLBuiltin);
  }
  }

clang/test/SemaOpenCL/fdeclare-opencl-builtins.cl

@@ -38,26 +38,6 @@ kernel void test_pointers(volatile global void *global_p, global const int4 *a)
 
  prefetch(a, 2);
 
- atom_add((volatile __global int *)global_p, i);
-#if !defined(__OPENCL_CPP_VERSION__) && __OPENCL_C_VERSION__ < CL_VERSION_1_1
-// expected-error@-2{{no matching function for call to 'atom_add'}}
-
-// There are two potential definitions of the function "atom_add", both are
-// currently disabled because the associated extension is disabled.
-// expected-note@-6{{candidate function not viable: cannot pass pointer to address space '__global' as a pointer to address space '__local' in 1st argument}}
-// expected-note@-7{{candidate function not viable: no known conversion}}
-// expected-note@-8{{candidate function not viable: no known conversion}}
-// expected-note@-9{{candidate function not viable: no known conversion}}
-// expected-note@-10{{candidate unavailable as it requires OpenCL extension 'cl_khr_global_int32_base_atomics' to be enabled}}
-// expected-note@-11{{candidate unavailable as it requires OpenCL extension 'cl_khr_global_int32_base_atomics' to be enabled}}
-// expected-note@-12{{candidate unavailable as it requires OpenCL extension 'cl_khr_int64_base_atomics' to be enabled}}
-// expected-note@-13{{candidate unavailable as it requires OpenCL extension 'cl_khr_int64_base_atomics' to be enabled}}
-#endif
-
-#if __OPENCL_C_VERSION__ < CL_VERSION_1_1
-#pragma OPENCL EXTENSION cl_khr_global_int32_base_atomics : enable
-#endif
-
  atom_add((volatile __global int *)global_p, i);
  atom_cmpxchg((volatile __global unsigned int *)global_p, ui, ui);
 }
@@ -146,11 +126,9 @@ kernel void basic_image_writeonly(write_only image1d_buffer_t image_write_only_i
 
 kernel void basic_subgroup(global uint *out) {
  out[0] = get_sub_group_size();
-#if defined(__OPENCL_CPP_VERSION__)
- // expected-error@-2{{no matching function for call to 'get_sub_group_size'}}
- // expected-note@-3{{candidate unavailable as it requires OpenCL extension 'cl_khr_subgroups' to be enabled}}
-#else
- // expected-error@-5{{use of declaration 'get_sub_group_size' requires cl_khr_subgroups extension to be enabled}}
+#if __OPENCL_C_VERSION__ <= CL_VERSION_1_2 && !defined(__OPENCL_CPP_VERSION__)
+ // expected-error@-2{{implicit declaration of function 'get_sub_group_size' is invalid in OpenCL}}
+ // expected-error@-3{{implicit conversion changes signedness}}
 #endif
 }