gcc: Add support for Apple's Block extension

Block objects [1] are a C-level syntactic and runtime feature. They
are similar to standard C functions, but in addition to executable
code they may also contain variable bindings to automatic (stack)
or managed (heap) memory. A block can therefore maintain a set of
state (data) that it can use to impact behavior when executed.

This port is based on Apple's GCC 5646 with some bugfixes from
Apple GCC 5666.3. It has some small differences with the support
in clang, which remains the recommended compiler.

Perhaps the most notable difference is that in GCC that __block
is not actually a keyword, but a macro. There will be workaround
for this issue in a near future. Other issues can be consulted in
the clang documentation [2]

For better compatiblity with Apple's GCC and llvm-gcc some related
fixes and features from Apple have been included. Support for the
non-standard nested functions in GCC is now off by default.

No effort was made to update the ObjC support since FreeBSD doesn't
carry ObjC in the base system, but some of the code crept in and
was more difficult to remove than to adjust.

Reference:
[1]
https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/Blocks/Articles/00_Introduction.html
[2]
http://clang.llvm.org/compatibility.html#block-variable-initialization

Obtained from:	Apple GCC 4.2
MFC after:	3 weeks

1 files changed, 30 insertions, 0 deletions

diff --git a/contrib/gcc/tree.c b/contrib/gcc/tree.c
index 8e0b801..a020bb1 100644
--- a/contrib/gcc/tree.c
+++ b/contrib/gcc/tree.c
@@ -69,6 +69,10 @@ const char *const tree_code_class_strings[] =
   "expression",
 };
 
+/* APPLE LOCAL begin 6353006  */
+tree generic_block_literal_struct_type;
+/* APPLE LOCAL end 6353006  */
+
 /* obstack.[ch] explicitly declined to prototype this.  */
 extern int _obstack_allocated_p (struct obstack *h, void *obj);
 
@@ -5016,6 +5020,31 @@ build_pointer_type (tree to_type)
   return build_pointer_type_for_mode (to_type, ptr_mode, false);
 }
 
+/* APPLE LOCAL begin radar 5732232 - blocks */
+tree
+build_block_pointer_type (tree to_type)
+{
+  tree t;
+
+  /* APPLE LOCAL begin radar 6300081 & 6353006 */
+  if (!generic_block_literal_struct_type)
+      generic_block_literal_struct_type = 
+      lang_hooks.build_generic_block_struct_type ();
+  /* APPLE LOCAL end radar 6300081 & 6353006 */
+
+  t = make_node (BLOCK_POINTER_TYPE);
+
+  TREE_TYPE (t) = to_type;
+  TYPE_MODE (t) = ptr_mode;
+
+  /* Lay out the type.  This function has many callers that are concerned
+     with expression-construction, and this simplifies them all.  */
+  layout_type (t);
+
+  return t;
+}
+/* APPLE LOCAL end radar 5732232 - blocks */
+
 /* Same as build_pointer_type_for_mode, but for REFERENCE_TYPE.  */
 
 tree
@@ -7771,4 +7800,5 @@ empty_body_p (tree stmt)
   return true;
 }
 
+
 #include "gt-tree.h"