[OpenCL] Added nosvm attribute for OpenCL v2.0.

It is not widely used and removed from OpenCL v2.1.

This change modifies Clang to parse the attribute for OpenCL
but ignores it afterwards.

Patch by Liu Yaxun (Sam)!

Differential Revision: http://reviews.llvm.org/D17861



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@265006 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/Attr.td

@@ -239,6 +239,7 @@ def MicrosoftExt : LangOpt<"MicrosoftExt">;
 def Borland : LangOpt<"Borland">;
 def CUDA : LangOpt<"CUDA">;
 def COnly : LangOpt<"CPlusPlus", 1>;
+def OpenCL : LangOpt<"OpenCL">;
 
 // Defines targets for target-specific attributes. The list of strings should
 // specify architectures for which the target applies, based off the ArchType
@@ -719,6 +720,14 @@ def OpenCLGenericAddressSpace : TypeAttr {
   let Documentation = [OpenCLAddressSpaceGenericDocs];
 }
 
+def OpenCLNoSVM : Attr {
+  let Spellings = [GNU<"nosvm">];
+  let Subjects = SubjectList<[Var]>;
+  let Documentation = [OpenCLNoSVMDocs];
+  let LangOpts = [OpenCL];
+  let ASTNode = 0;
+}
+
 def Deprecated : InheritableAttr {
   let Spellings = [GCC<"deprecated">, Declspec<"deprecated">,
                    CXX11<"","deprecated", 201309>];

include/clang/Basic/AttrDocs.td

@@ -1773,6 +1773,17 @@ cannot point to the private address space.
   }];
 }
 
+def OpenCLNoSVMDocs : Documentation {
+  let Category = DocCatVariable;
+  let Content = [{
+OpenCL 2.0 supports the optional ``__attribute__((nosvm))`` qualifier for
+pointer variable. It informs the compiler that the pointer does not refer
+to a shared virtual memory region. See OpenCL v2.0 s6.7.2 for details.
+
+Since it is not widely used and has been removed from OpenCL 2.1, it is ignored
+by Clang.
+  }];
+}
 def NullabilityDocs : DocumentationCategory<"Nullability Attributes"> {
   let Content = [{
 Whether a particular pointer may be "null" is an important concern when working with pointers in the C family of languages. The various nullability attributes indicate whether a particular pointer can be null or not, which makes APIs more expressive and can help static analysis tools identify bugs involving null pointers. Clang supports several kinds of nullability attributes: the ``nonnull`` and ``returns_nonnull`` attributes indicate which function or method parameters and result types can never be null, while nullability type qualifiers indicate which pointer types can be null (``_Nullable``) or cannot be null (``_Nonnull``). 

include/clang/Basic/DiagnosticSemaKinds.td

@@ -2129,7 +2129,7 @@ def err_attribute_bad_neon_vector_size : Error<
 def err_attribute_requires_positive_integer : Error<
   "%0 attribute requires a positive integral compile time constant expression">;
 def err_attribute_requires_opencl_version : Error<
-  "%0 attribute requires OpenCL version %1 or above">;
+  "%0 attribute requires OpenCL version %1%select{| or above}2">;
 def warn_unsupported_target_attribute
     : Warning<"Ignoring unsupported '%0' in the target attribute string">,
     InGroup<IgnoredAttributes>;
@@ -7775,6 +7775,9 @@ def err_opencl_pointer_to_type : Error<
   "pointer to type %0 is invalid in OpenCL">;
 def err_opencl_type_can_only_be_used_as_function_parameter : Error <
   "type %0 can only be used as a function parameter in OpenCL">;
+def warn_opencl_attr_deprecated_ignored : Warning <
+  "%0 attribute is deprecated and ignored in OpenCL version %1">,
+  InGroup<IgnoredAttributes>;
 
 // OpenCL v2.0 s6.13.6 -- Builtin Pipe Functions
 def err_opencl_builtin_pipe_first_arg : Error<

lib/Sema/SemaDeclAttr.cpp

@@ -5214,6 +5214,15 @@ static void handleInternalLinkageAttr(Sema &S, Decl *D,
     D->addAttr(Internal);
 }
 
+static void handleOpenCLNoSVMAttr(Sema &S, Decl *D, const AttributeList &Attr) {
+  if (S.LangOpts.OpenCLVersion != 200)
+    S.Diag(Attr.getLoc(), diag::err_attribute_requires_opencl_version)
+        << Attr.getName() << "2.0" << 0;
+  else
+    S.Diag(Attr.getLoc(), diag::warn_opencl_attr_deprecated_ignored)
+        << Attr.getName() << "2.0";
+}
+
 /// Handles semantic checking for features that are common to all attributes,
 /// such as checking whether a parameter was properly specified, or the correct
 /// number of arguments were passed, etc.
@@ -5706,6 +5715,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case AttributeList::AT_SwiftIndirectResult:
     handleParameterABIAttr(S, D, Attr, ParameterABI::SwiftIndirectResult);
     break;
+  case AttributeList::AT_OpenCLNoSVM:
+    handleOpenCLNoSVMAttr(S, D, Attr);
+    break;
   case AttributeList::AT_InternalLinkage:
     handleInternalLinkageAttr(S, D, Attr);
     break;

lib/Sema/SemaStmtAttr.cpp

@@ -221,7 +221,7 @@ static Attr *handleOpenCLUnrollHint(Sema &S, Stmt *St, const AttributeList &A,
 
   if (S.getLangOpts().OpenCLVersion < 200) {
     S.Diag(A.getLoc(), diag::err_attribute_requires_opencl_version)
-        << A.getName() << "2.0";
+        << A.getName() << "2.0" << 1;
     return nullptr;
   }
 

test/SemaOpenCL/nosvm.cl

@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -verify %s
+// RUN: %clang_cc1 -verify -cl-std=CL2.0 -D CL20 %s
+// RUN: %clang_cc1 -verify -x c -D NOCL %s
+
+#ifndef NOCL
+kernel void f(__attribute__((nosvm)) global int* a);
+#ifndef CL20
+// expected-error@-2 {{'nosvm' attribute requires OpenCL version 2.0}}
+#else
+// expected-warning@-4 {{'nosvm' attribute is deprecated and ignored in OpenCL version 2.0}}
+#endif
+
+__attribute__((nosvm)) void g(); // expected-warning {{'nosvm' attribute only applies to variables}}
+
+#else
+void f(__attribute__((nosvm)) int* a); // expected-warning {{'nosvm' attribute ignored}}
+#endif