[OpenCL] Adjust diagnostic for subgroup support.

OpenCL C 3.0 __opencl_c_subgroups feature is slightly different
then other equivalent features and extensions (fp64 and 3d image writes):
OpenCL C 3.0 device can support the extension but not the feature.
cl_khr_subgroups requires subgroup independent forward progress.

This patch adjusts the check which is used when translating language
builtins to check either the extension or feature is supported.

Reviewed By: Anastasia

Differential Revision: https://reviews.llvm.org/D118999

(cherry picked from commit bfb1a33)

Author: azabazno

clang/lib/Sema/SemaChecking.cpp

@@ -1042,9 +1042,15 @@ static bool checkOpenCLBlockArgs(Sema &S, Expr *BlockArg) {
 }
 
 static bool checkOpenCLSubgroupExt(Sema &S, CallExpr *Call) {
-  if (!S.getOpenCLOptions().isSupported("cl_khr_subgroups", S.getLangOpts())) {
+  // OpenCL device can support extension but not the feature as extension
+  // requires subgroup independent forward progress, but subgroup independent
+  // forward progress is optional in OpenCL C 3.0 __opencl_c_subgroups feature.
+  if (!S.getOpenCLOptions().isSupported("cl_khr_subgroups", S.getLangOpts()) &&
+      !S.getOpenCLOptions().isSupported("__opencl_c_subgroups",
+                                        S.getLangOpts())) {
     S.Diag(Call->getBeginLoc(), diag::err_opencl_requires_extension)
-        << 1 << Call->getDirectCallee() << "cl_khr_subgroups";
+        << 1 << Call->getDirectCallee()
+        << "cl_khr_subgroups or __opencl_c_subgroups";
     return true;
   }
   return false;

clang/test/SemaOpenCL/cl20-device-side-enqueue.cl

@@ -4,7 +4,7 @@
 // RUN: %clang_cc1 %s -cl-std=CL2.0 -triple "spir64-unknown-unknown" -verify -pedantic -fsyntax-only -Wconversion -DWCONV -DQUALS=
 // RUN: %clang_cc1 %s -cl-std=CL2.0 -triple "spir64-unknown-unknown" -verify -pedantic -fsyntax-only -Wconversion -DWCONV -DQUALS="const volatile"
 // RUN: %clang_cc1 %s -cl-std=CL3.0 -triple "spir-unknown-unknown" -verify -pedantic -fsyntax-only -DB32 -DQUALS=
-// RUN: %clang_cc1 %s -cl-std=CL3.0 -triple "spir-unknown-unknown" -verify -pedantic -fsyntax-only -DB32 -DQUALS= -cl-ext=-cl_khr_subgroups
+// RUN: %clang_cc1 %s -cl-std=CL3.0 -triple "spir-unknown-unknown" -verify -pedantic -fsyntax-only -DB32 -DQUALS= -cl-ext=-cl_khr_subgroups,-__opencl_c_subgroups
 // RUN: %clang_cc1 %s -cl-std=CL3.0 -triple "spir-unknown-unknown" -verify -pedantic -fsyntax-only -DB32 -DQUALS="const volatile"
 // RUN: %clang_cc1 %s -cl-std=CL3.0 -triple "spir64-unknown-unknown" -verify -pedantic -fsyntax-only -Wconversion -DWCONV -DQUALS=
 // RUN: %clang_cc1 %s -cl-std=CL3.0 -triple "spir64-unknown-unknown" -verify -pedantic -fsyntax-only -Wconversion -DWCONV -DQUALS="const volatile"
@@ -241,12 +241,12 @@ kernel void bar(global unsigned int *buf)
 kernel void foo1(global unsigned int *buf)
 {
   ndrange_t n;
-  buf[0] = get_kernel_max_sub_group_size_for_ndrange(n, ^(){}); // expected-error {{use of declaration 'get_kernel_max_sub_group_size_for_ndrange' requires cl_khr_subgroups support}}
+  buf[0] = get_kernel_max_sub_group_size_for_ndrange(n, ^(){}); // expected-error {{use of declaration 'get_kernel_max_sub_group_size_for_ndrange' requires cl_khr_subgroups or __opencl_c_subgroups support}}
 }
 
 kernel void bar1(global unsigned int *buf)
 {
   ndrange_t n;
-  buf[0] = get_kernel_sub_group_count_for_ndrange(n, ^(){}); // expected-error {{use of declaration 'get_kernel_sub_group_count_for_ndrange' requires cl_khr_subgroups support}}
+  buf[0] = get_kernel_sub_group_count_for_ndrange(n, ^(){}); // expected-error {{use of declaration 'get_kernel_sub_group_count_for_ndrange' requires cl_khr_subgroups or __opencl_c_subgroups support}}
 }
 #endif // ifdef cl_khr_subgroups