From: Ivan Maidanski <ivmai@mail.ru>
Date: Mon, 15 Oct 2018 20:54:57 +0000 (+0300)
Subject: New API function to get size of object debug header
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=85e3083ff;p=gc

New API function to get size of object debug header

GC_get_debug_header_size() is exported in addition to
GC_debug_header_size variable.  The usage of the latter is deprecated.

* dbg_mlc.c [CPPCHECK] (GC_start_debugging_inner): Call
GC_noop1(GC_debug_header_size) to suppress a cppcheck warning about
unused symbol.
* dbg_mlc.c (GC_debug_header_size): Add const.
* dbg_mlc.c (GC_get_debug_header_size): New API function definition.
* include/gc_config_macros.h (GC_ATTR_CONST): New macro.
* include/gc_mark.h (GC_debug_header_size): Add GC_ATTR_DEPRECATED and
const; update comment.
* include/gc_mark.h (GC_get_debug_header_size): New API public const
function declaration; move the comment from GC_debug_header_size.
* include/gc_mark.h (GC_USR_PTR_FROM_BASE): Use
GC_get_debug_header_size() instead of GC_debug_header_size.
---

diff --git a/dbg_mlc.c b/dbg_mlc.c
index 4d547c15..a8bd8154 100644
--- a/dbg_mlc.c
+++ b/dbg_mlc.c
@@ -489,9 +489,16 @@ GC_INNER void GC_start_debugging_inner(void)
   GC_print_heap_obj = GC_debug_print_heap_obj_proc;
   GC_debugging_started = TRUE;
   GC_register_displacement_inner((word)sizeof(oh));
+# if defined(CPPCHECK)
+    GC_noop1(GC_debug_header_size);
+# endif
 }
 
-size_t GC_debug_header_size = sizeof(oh);
+const size_t GC_debug_header_size = sizeof(oh);
+
+GC_API size_t GC_CALL GC_get_debug_header_size(void) {
+  return sizeof(oh);
+}
 
 GC_API void GC_CALL GC_debug_register_displacement(size_t offset)
 {
diff --git a/include/gc_config_macros.h b/include/gc_config_macros.h
index d656e01e..b999316d 100644
--- a/include/gc_config_macros.h
+++ b/include/gc_config_macros.h
@@ -276,6 +276,14 @@
 # endif
 #endif
 
+#ifndef GC_ATTR_CONST
+# if GC_GNUC_PREREQ(4, 0)
+#   define GC_ATTR_CONST __attribute__((__const__))
+# else
+#   define GC_ATTR_CONST /* empty */
+# endif
+#endif
+
 #ifndef GC_ATTR_DEPRECATED
 # ifdef GC_BUILD
 #   undef GC_ATTR_DEPRECATED
diff --git a/include/gc_mark.h b/include/gc_mark.h
index b5201cb7..ecc6c8a7 100644
--- a/include/gc_mark.h
+++ b/include/gc_mark.h
@@ -152,12 +152,17 @@ GC_API struct GC_ms_entry * GC_CALL GC_mark_and_push(void * /* obj */,
            (GC_word)(obj) <= (GC_word)GC_greatest_plausible_heap_addr ? \
            GC_mark_and_push(obj, msp, lim, src) : (msp))
 
-GC_API size_t GC_debug_header_size;
-       /* The size of the header added to objects allocated through    */
-       /* the GC_debug routines.                                       */
-       /* Defined as a variable so that client mark procedures don't   */
-       /* need to be recompiled for collector version changes.         */
-#define GC_USR_PTR_FROM_BASE(p) ((void *)((char *)(p) + GC_debug_header_size))
+/* The size of the header added to objects allocated through the        */
+/* GC_debug routines.  Defined as a function so that client mark        */
+/* procedures do not need to be recompiled for the collector library    */
+/* version changes.                                                     */
+GC_API GC_ATTR_CONST size_t GC_CALL GC_get_debug_header_size(void);
+#define GC_USR_PTR_FROM_BASE(p) \
+                ((void *)((char *)(p) + GC_get_debug_header_size()))
+
+/* The same but defined as a variable.  Exists only for the backward    */
+/* compatibility.                                                       */
+GC_API GC_ATTR_DEPRECATED const size_t GC_debug_header_size;
 
 /* And some routines to support creation of new "kinds", e.g. with      */
 /* custom mark procedures, by language runtimes.                        */