[OpenCL] Ignore parentheses for sampler initialization

[svenvh]

Summary

The sampler handling logic in SemaInit.cpp would inadvertently treat
parentheses around sampler arguments as an implicit cast, leading to
an unreachable "can't implicitly cast lvalue to rvalue with
this cast kind". Fix by ignoring parentheses once we are in the
sampler initializer case.

[Anastasia]

LGTM! Thanks!

clang/lib/Sema/SemaInit.cpp

case SK_OCLSamplerInit: {
       // For file-scope variables, since they cannot be initialized by function
       // call of __translate_sampler_initializer in LLVM IR, their references
       // need to be replaced by a cast from their literal initializers to
       // sampler type. Since sampler variables can only be used in function
       // calls as arguments, we only need to replace them when handling the
       // argument passing.
       assert(Step->Type->isSamplerT() &&
              "Sampler initialization on non-sampler type.");
-      Expr *Init = CurInit.get();
+      Expr *Init = CurInit.get()->IgnoreParens();
       QualType SourceType = Init->getType();
       // Case 1
       if (Entity.isParameterKind()) {
         if (!SourceType->isSamplerT() && !SourceType->isIntegerType()) {
           S.Diag(Kind.getLocation(), diag::err_sampler_argument_required)
             << SourceType;
           break;
         } else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Init)) {

clang/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
 #define CLK_FILTER_NEAREST              0x10
 #define CLK_FILTER_LINEAR               0x20
 
+typedef float float4 __attribute__((ext_vector_type(4)));
+float4 read_imagef(read_only image1d_t, sampler_t, float);
+
 constant sampler_t glb_smp = CLK_ADDRESS_CLAMP_TO_EDGE | CLK_NORMALIZED_COORDS_TRUE | CLK_FILTER_LINEAR;
 constant sampler_t glb_smp2; // expected-error{{variable in constant address space must be initialized}}
 global sampler_t glb_smp3 = CLK_ADDRESS_CLAMP_TO_EDGE | CLK_NORMALIZED_COORDS_TRUE | CLK_FILTER_NEAREST; // expected-error{{sampler type cannot be used with the __local and __global address space qualifiers}} expected-error {{global sampler requires a const or constant address space qualifier}}
 const global sampler_t glb_smp3_const = CLK_ADDRESS_CLAMP_TO_EDGE | CLK_NORMALIZED_COORDS_TRUE | CLK_FILTER_LINEAR;  // expected-error{{sampler type cannot be used with the __local and __global address space qualifiers}}
 
 constant sampler_t glb_smp4 = 0;
 #ifdef CHECK_SAMPLER_VALUE
 // expected-warning@-2{{sampler initializer has invalid Filter Mode bits}}
void bar() {
   sampler_t smp2 = CLK_ADDRESS_CLAMP_TO_EDGE | CLK_NORMALIZED_COORDS_TRUE | CLK_FILTER_NEAREST;
   smp1=smp2; //expected-error{{invalid operands to binary expression ('sampler_t' and 'sampler_t')}}
   smp1+1; //expected-error{{invalid operands to binary expression ('sampler_t' and 'int')}}
   &smp1; //expected-error{{invalid argument type 'sampler_t' to unary expression}}
   *smp2; //expected-error{{invalid argument type 'sampler_t' to unary expression}}
   foo(smp1+1); //expected-error{{invalid operands to binary expression ('sampler_t' and 'int')}}
 }
 
+void smp_args(read_only image1d_t image) {
+  // Test that parentheses around sampler arguments are ignored.
+  float4 res = read_imagef(image, (glb_smp10), 0.0f);
+}