[OpenCL] Re-enable supported core extensions based on opencl version when disabling all extensions using pragma

Differential Revision: https://reviews.llvm.org/D28257

llvm-svn: 291243
diff --git a/clang/lib/Parse/ParsePragma.cpp b/clang/lib/Parse/ParsePragma.cpp
index 2dc6a07..8973323 100644
--- a/clang/lib/Parse/ParsePragma.cpp
+++ b/clang/lib/Parse/ParsePragma.cpp
@@ -506,10 +506,12 @@
   // overriding all previously issued extension directives, but only if the
   // behavior is set to disable."
   if (Name == "all") {
-    if (State == Disable)
+    if (State == Disable) {
       Opt.disableAll();
-    else
+      Opt.enableSupportedCore(getLangOpts().OpenCLVersion);
+    } else {
       PP.Diag(NameLoc, diag::warn_pragma_expected_predicate) << 1;
+    }
   } else if (State == Begin) {
     if (!Opt.isKnown(Name) ||
         !Opt.isSupported(Name, getLangOpts().OpenCLVersion)) {