[OpenCL] Enable unroll hint for OpenCL 1.x.

[echuraev]

Summary

Although the feature was introduced only in OpenCL C v2.0 spec., it's useful for OpenCL 1.x too and doesn't require HW support.

[Anastasia]

lib/Sema/SemaStmtAttr.cpp

232

The comment above refers to v2.0, could we update it reflecting the fact that we now allow the feature in all OpenCL versions.

[Anastasia]

LGTM! Thanks!

lib/Sema/SemaStmtAttr.cpp

 }
 
 static Attr *handleOpenCLUnrollHint(Sema &S, Stmt *St, const AttributeList &A,
                                     SourceRange Range) {
   // OpenCL v2.0 s6.11.5 - opencl_unroll_hint can have 0 arguments (compiler
   // determines unrolling factor) or 1 argument (the unroll factor provided
   // by the user).
 
-  if (S.getLangOpts().OpenCLVersion < 200) {
-    S.Diag(A.getLoc(), diag::err_attribute_requires_opencl_version)
-        << A.getName() << "2.0" << 1;
-    return nullptr;
-  }
-
   unsigned NumArgs = A.getNumArgs();
 
   if (NumArgs > 1) {
     S.Diag(A.getLoc(), diag::err_attribute_too_many_arguments) << A.getName()
                                                                << 1;
     return nullptr;
   }
 

test/CodeGenOpenCL/unroll-hint.cl

 // RUN: %clang_cc1 -emit-llvm -O0 -cl-std=CL2.0 -o - %s | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm -O0 -cl-std=CL1.2 -o - %s | FileCheck %s
 
 /*** for ***/
 void for_count()
 {
 // CHECK-LABEL: for_count
     __attribute__((opencl_unroll_hint(8)))
     for( int i = 0; i < 1000; ++i);
 // CHECK: br label %{{.*}}, !llvm.loop ![[FOR_COUNT:.*]]

test/SemaOpenCL/unroll-hint.cl

-//RUN: %clang_cc1 -O0 -fsyntax-only -verify %s
-//RUN: %clang_cc1 -O0 -cl-std=CL2.0 -fsyntax-only -verify -DCL20 %s
+//RUN: %clang_cc1 -O0 -cl-std=CL2.0 -fsyntax-only -verify %s
 
-kernel void D (global int *x) {
-  int i = 10;
-#ifndef CL20
-  // expected-error@+2 {{'opencl_unroll_hint' attribute requires OpenCL version 2.0 or above}}
-#endif
-  __attribute__((opencl_unroll_hint))
-  do {
-  } while(i--);
-}
-
-#ifdef CL20
 kernel void C (global int *x) {
   int I = 3;
   __attribute__((opencl_unroll_hint(I))) // expected-error {{'opencl_unroll_hint' attribute requires an integer constant}}
   while (I--);
 }
 
 kernel void E() {
   __attribute__((opencl_unroll_hint(2,4))) // expected-error {{'opencl_unroll_hint' attribute takes no more than 1 argument}}
   for(int i=0; i<100; i++);
 }
 
 kernel void F() {
   __attribute__((opencl_unroll_hint(-1))) // expected-error {{'opencl_unroll_hint' attribute requires a positive integral compile time constant expression}}
   for(int i=0; i<100; i++);
 }
-#endif