[OpenCL] Added diagnostic for checking length of vector

[Anastasia]

lib/Sema/SemaExprMember.cpp

287

The format is normally: OpenCL v1.1, s6.1.7

288

Does this text have much relation to the function? I don't feel that copying it from the spec is helping much in understanding of this function. It's probably just Ok to have the reference to the spec section and concisely summarize that the component swizzle length must be in accordance with the acceptable vector sizes.

Also would it be better to rename this to something like:

IsValidOpenCLComponentSwizzleLength

389

I think the logic in this function is all for OpenCL, but we didn't check it . Anyways, let's leave it for now.

395

Variable name doesn't adhere the coding style:
http://llvm.org/docs/CodingStandards.html#name-types-functions-variables-and-enumerators-properly

Also you could use CompName->getLength() instead of constructing a new StringRef object.

test/SemaOpenCL/vector_swizzle_length.cl

8

Could we add a non-numeric swizzle too?

[Anastasia]

LGTM! Thanks!

include/clang/Basic/DiagnosticSemaKinds.td

def err_invalid_astype_of_different_size : Error<
   "invalid reinterpretation: sizes of %0 and %1 must match">;
 def err_static_kernel : Error<
   "kernel functions cannot be declared static">;
 def err_opencl_ptrptr_kernel_param : Error<
   "kernel parameter cannot be declared as a pointer to a pointer">;
 def err_kernel_arg_address_space : Error<
   "pointer arguments to kernel functions must reside in '__global', "
   "'__constant' or '__local' address space">;
+def err_opencl_ext_vector_component_invalid_length : Error<
+  "vector component access has invalid length %0.  Supported: 1,2,3,4,8,16.">;
 def err_opencl_function_variable : Error<
   "%select{non-kernel function|function scope}0 variable cannot be declared in %1 address space">;
 def err_static_function_scope : Error<
   "variables in function scope cannot be declared static">;
 def err_opencl_bitfields : Error<
   "bit-fields are not supported in OpenCL">;
 def err_opencl_vla : Error<
   "variable length arrays are not supported in OpenCL">;

lib/Sema/SemaExprMember.cpp

IsRGBA(char c) {
   case 'b':
   case 'a':
     return true;
   default:
     return false;
   }
 }
 
+// OpenCL spec (Section 6.1.7 Vector Components):
+// The component group notation can occur on the left hand side of an expression. To form an lvalue,
+// swizzling must be applied to an l-value of vector type, contain no duplicate components,
+// and it results in an l-value of scalar or vector type, depending on number of components
+// specified. Each component must be a supported scalar or vector type.
+static bool IsValidSwizzleLength(unsigned len)
+{
+  return (len >= 1 && len <= 4) || len == 8 || len == 16;
+}
+
 /// Check an ext-vector component access expression.
 ///
 /// VK should be set in advance to the value kind of the base
 /// expression.
 static QualType
 CheckExtVectorComponent(Sema &S, QualType baseType, ExprValueKind &VK,
                         SourceLocation OpLoc, const IdentifierInfo *CompName,
                         SourceLocation CompLoc) {
while (*compStr) {
       if (!vecType->isAccessorWithinNumElements(*compStr++, HexSwizzle)) {
         S.Diag(OpLoc, diag::err_ext_vector_component_exceeds_length)
           << baseType << SourceRange(CompLoc);
         return QualType();
       }
     }
   }
 
+  if (S.getLangOpts().OpenCL && !HalvingSwizzle) {
+    compStr = CompName->getNameStart();
+
+    if (HexSwizzle)
+      compStr++;
+
+    unsigned swizzleLength = StringRef(compStr).size();
+    if (IsValidSwizzleLength(swizzleLength) == false) {
+      S.Diag(OpLoc, diag::err_opencl_ext_vector_component_invalid_length)
+        << swizzleLength << SourceRange(CompLoc);
+      return QualType();
+    }
+  }
+
   // The component accessor looks fine - now we need to compute the actual type.
   // The vector type is implied by the component accessor. For example,
   // vec4.b is a float, vec4.xy is a vec2, vec4.rgb is a vec3, etc.
   // vec4.s0 is a float, vec4.s23 is a vec3, etc.
   // vec4.hi, vec4.lo, vec4.e, and vec4.o all return vec2.
   unsigned CompSize = HalvingSwizzle ? (vecType->getNumElements() + 1) / 2
                                      : CompName->getLength();
   if (HexSwizzle)

test/SemaOpenCL/vector_swizzle_length.cl

+// RUN: %clang_cc1 %s -verify -pedantic -fsyntax-only
+
+typedef float float8 __attribute__((ext_vector_type(8)));
+
+void foo() {
+    float8 f2 = (float8)(0, 0, 0, 0, 0, 0, 0, 0);
+
+    f2.s01234; // expected-error {{vector component access has invalid length 5.  Supported: 1,2,3,4,8,16}}
+}