[OpenCL] Fix file-scope const sampler variable for 2.0

[yaxunl]

Summary

OpenCL spec v2.0 s6.13.14:

Samplers can also be declared as global constants in the program
source using the following syntax.

   const sampler_t <sampler name> = <value>

This works fine for OpenCL 1.2 but fails for 2.0, because clang duduces
address space of file-scope const sampler variable to be in global address
space whereas spec v2.0 s6.9.b forbids file-scope sampler variable to be
in global address space.

The fix is not to deduce address space for file-scope sampler variables.

[yaxunl]

Add full diff.

[Anastasia]

Makes sense. LGTM! Thanks!

lib/Sema/SemaType.cpp

       T->isDependentType() ||
       // Do not deduce addr space of decltype because it will be taken from
       // its argument.
-      T->isDecltypeType())
+      T->isDecltypeType() ||
+      // OpenCL spec v2.0 s6.9.b:
+      // The sampler type cannot be used with the __local and __global address
+      // space qualifiers.
+      // OpenCL spec v2.0 s6.13.14:
+      // Samplers can also be declared as global constants in the program
+      // source using the following syntax.
+      //   const sampler_t <sampler name> = <value>
+      // In codegen, file-scope sampler type variable has special handing and
+      // does not rely on address space qualifier. On the other hand, deducing
+      // address space of const sampler file-scope variable as global address
+      // space causes spurious diagnostic about __global address space
+      // qualifier, therefore do not deduce address space of file-scope sampler
+      // type variable.
+      (D.getContext() == DeclaratorContext::FileContext && T->isSamplerT()))
     return;
 
   LangAS ImpAddr = LangAS::Default;

test/CodeGenOpenCL/sampler.cl

 // RUN: %clang_cc1 %s -emit-llvm -triple spir-unknown-unknown -o - -O0 | FileCheck %s
+// RUN: %clang_cc1 %s -cl-std=CL2.0 -emit-llvm -triple spir-unknown-unknown -o - -O0 | FileCheck %s
 //
 // This test covers 5 cases of sampler initialzation:
 //   1. function argument passing

 //      1b. argument is a function-scope variable
 //      1c. argument is one of caller function's parameters
 //   2. variable initialization
-//      2a. initializing a file-scope variable
+//      2a. initializing a file-scope variable with constant addr space qualifier
 //      2b. initializing a function-scope variable
+//      2c. initializing a file-scope variable with const qualifier
 
 #define CLK_ADDRESS_CLAMP_TO_EDGE       2
 #define CLK_NORMALIZED_COORDS_TRUE      1

 constant sampler_t glb_smp = CLK_ADDRESS_CLAMP_TO_EDGE | CLK_NORMALIZED_COORDS_TRUE | CLK_FILTER_LINEAR;
 // CHECK-NOT: glb_smp
 
+// Case 2c
+const sampler_t glb_smp_const = CLK_ADDRESS_CLAMP_TO_EDGE | CLK_NORMALIZED_COORDS_TRUE | CLK_FILTER_LINEAR;
+// CHECK-NOT: glb_smp_const
+
 int get_sampler_initializer(void);
 
 void fnc4smp(sampler_t s) {}

   // CHECK: [[SAMP:%[0-9]+]] = load %opencl.sampler_t addrspace(2)*, %opencl.sampler_t addrspace(2)** [[smp_ptr]]
   // CHECK: call spir_func void @fnc4smp(%opencl.sampler_t addrspace(2)* [[SAMP]])
 
-  // Case 1a
+  // Case 1a/2a
   fnc4smp(glb_smp);
   // CHECK: [[SAMP:%[0-9]+]] = call %opencl.sampler_t addrspace(2)* @__translate_sampler_initializer(i32 35)
   // CHECK: call spir_func void @fnc4smp(%opencl.sampler_t addrspace(2)* [[SAMP]])
 
+  // Case 1a/2c
+  fnc4smp(glb_smp_const);
+  // CHECK: [[SAMP:%[0-9]+]] = call %opencl.sampler_t addrspace(2)* @__translate_sampler_initializer(i32 35)
+  // CHECK: call spir_func void @fnc4smp(%opencl.sampler_t addrspace(2)* [[SAMP]])
+
   // Case 1c
   fnc4smp(smp_par);
   // CHECK: [[SAMP:%[0-9]+]] = load %opencl.sampler_t addrspace(2)*, %opencl.sampler_t addrspace(2)** [[smp_par_ptr]]

test/SemaOpenCL/sampler_t.cl

 // RUN: %clang_cc1 %s -verify -pedantic -fsyntax-only
 // RUN: %clang_cc1 %s -verify -pedantic -fsyntax-only -DCHECK_SAMPLER_VALUE -Wspir-compat -triple amdgcn--amdhsa
 // RUN: %clang_cc1 %s -verify -pedantic -fsyntax-only -DCHECK_SAMPLER_VALUE -triple spir-unknown-unknown
+// RUN: %clang_cc1 %s -cl-std=CL2.0 -verify -pedantic -fsyntax-only
+// RUN: %clang_cc1 %s -cl-std=CL2.0 -verify -pedantic -fsyntax-only -DCHECK_SAMPLER_VALUE -Wspir-compat -triple amdgcn--amdhsa
+// RUN: %clang_cc1 %s -cl-std=CL2.0 -verify -pedantic -fsyntax-only -DCHECK_SAMPLER_VALUE -triple spir-unknown-unknown
 
 #define CLK_ADDRESS_CLAMP_TO_EDGE       2
 #define CLK_NORMALIZED_COORDS_TRUE      1

   sampler_t sa[] = {argsmp, glb_smp}; // expected-error {{array of 'sampler_t' type is invalid in OpenCL}}
 }
 
+#if __OPENCL_C_VERSION__ == 200
+void bad(sampler_t*); // expected-error{{pointer to type '__generic sampler_t' is invalid in OpenCL}}
+#else
 void bad(sampler_t*); // expected-error{{pointer to type 'sampler_t' is invalid in OpenCL}}
+#endif
 
 void bar() {
   sampler_t smp1 = CLK_ADDRESS_CLAMP_TO_EDGE | CLK_NORMALIZED_COORDS_TRUE | CLK_FILTER_LINEAR;