Bug 1145051: Replace uses of NS_ATTR_MALLOC with new MOZ_ALLOCATOR fr…

…om mfbt/Attributes.h. r=glandium

--HG--
extra : rebase_source : 294215445f084687ed7fa51b88e7a22e586447a2

configure.in

@@ -3436,13 +3436,6 @@ AC_CACHE_CHECK(for __attribute__((always_inline)),
                                ac_cv_attribute_always_inline=yes,
                                ac_cv_attribute_always_inline=no)])
 
-AC_CACHE_CHECK(for __attribute__((malloc)),
-               ac_cv_attribute_malloc,
-               [AC_TRY_COMPILE([void* f(int) __attribute__((malloc));],
-                               [],
-                               ac_cv_attribute_malloc=yes,
-                               ac_cv_attribute_malloc=no)])
-
 AC_CACHE_CHECK(for __attribute__((warn_unused_result)),
                ac_cv_attribute_warn_unused,
                [AC_TRY_COMPILE([int f(void) __attribute__((warn_unused_result));],
@@ -3486,14 +3479,6 @@ dnl ========================================================
 dnl The macros used for command line options
 dnl are defined in build/autoconf/altoptions.m4.
 
-dnl If the compiler supports these attributes, define them as
-dnl convenience macros.
-if test "$ac_cv_attribute_malloc" = yes ; then
-  AC_DEFINE(NS_ATTR_MALLOC, [__attribute__((malloc))])
-else
-  AC_DEFINE(NS_ATTR_MALLOC,)
-fi
-
 if test "$ac_cv_attribute_warn_unused" = yes ; then
   AC_DEFINE(NS_WARN_UNUSED_RESULT, [__attribute__((warn_unused_result))])
 else

js/src/configure.in

@@ -2659,13 +2659,6 @@ AC_CACHE_CHECK(for __attribute__((always_inline)),
                                ac_cv_attribute_always_inline=yes,
                                ac_cv_attribute_always_inline=no)])
 
-AC_CACHE_CHECK(for __attribute__((malloc)),
-               ac_cv_attribute_malloc,
-               [AC_TRY_COMPILE([void* f(int) __attribute__((malloc));],
-                               [],
-                               ac_cv_attribute_malloc=yes,
-                               ac_cv_attribute_malloc=no)])
-
 AC_CACHE_CHECK(for __attribute__((warn_unused_result)),
                ac_cv_attribute_warn_unused,
                [AC_TRY_COMPILE([int f(void) __attribute__((warn_unused_result));],
@@ -2708,14 +2701,6 @@ dnl ========================================================
 dnl The macros used for command line options
 dnl are defined in build/autoconf/altoptions.m4.
 
-dnl If the compiler supports these attributes, define them as
-dnl convenience macros.
-if test "$ac_cv_attribute_malloc" = yes ; then
-  AC_DEFINE(NS_ATTR_MALLOC, [__attribute__((malloc))])
-else
-  AC_DEFINE(NS_ATTR_MALLOC,)
-fi
-
 if test "$ac_cv_attribute_warn_unused" = yes ; then
   AC_DEFINE(NS_WARN_UNUSED_RESULT, [__attribute__((warn_unused_result))])
 else

memory/mozalloc/mozalloc.h

@@ -40,8 +40,8 @@
 #if defined(__SUNPRO_C) || defined(__SUNPRO_CC)
 #  undef NS_WARN_UNUSED_RESULT
 #  define NS_WARN_UNUSED_RESULT
-#  undef NS_ATTR_MALLOC
-#  define NS_ATTR_MALLOC
+#  undef MOZ_ALLOCATOR
+#  define MOZ_ALLOCATOR
 #endif
 
 #if defined(__cplusplus)
@@ -76,24 +76,24 @@ extern "C" {
  */
 
 MFBT_API void* moz_xmalloc(size_t size)
-    NS_ATTR_MALLOC NS_WARN_UNUSED_RESULT;
+    MOZ_ALLOCATOR;
 
 MFBT_API void* moz_xcalloc(size_t nmemb, size_t size)
-    NS_ATTR_MALLOC NS_WARN_UNUSED_RESULT;
+    MOZ_ALLOCATOR;
 
 MFBT_API void* moz_xrealloc(void* ptr, size_t size)
-    NS_ATTR_MALLOC NS_WARN_UNUSED_RESULT;
+    MOZ_ALLOCATOR;
 
 MFBT_API char* moz_xstrdup(const char* str)
-    NS_ATTR_MALLOC NS_WARN_UNUSED_RESULT;
+    MOZ_ALLOCATOR;
 
 MFBT_API size_t moz_malloc_usable_size(void *ptr);
 
 MFBT_API size_t moz_malloc_size_of(const void *ptr);
 
 #if defined(HAVE_STRNDUP)
 MFBT_API char* moz_xstrndup(const char* str, size_t strsize)
-    NS_ATTR_MALLOC NS_WARN_UNUSED_RESULT;
+    MOZ_ALLOCATOR;
 #endif /* if defined(HAVE_STRNDUP) */
 
 
@@ -108,13 +108,13 @@ MFBT_API int moz_posix_memalign(void **ptr, size_t alignment, size_t size)
 
 #if defined(HAVE_MEMALIGN)
 MFBT_API void* moz_xmemalign(size_t boundary, size_t size)
-    NS_ATTR_MALLOC NS_WARN_UNUSED_RESULT;
+    MOZ_ALLOCATOR;
 #endif /* if defined(HAVE_MEMALIGN) */
 
 
 #if defined(HAVE_VALLOC)
 MFBT_API void* moz_xvalloc(size_t size)
-    NS_ATTR_MALLOC NS_WARN_UNUSED_RESULT;
+    MOZ_ALLOCATOR;
 #endif /* if defined(HAVE_VALLOC) */
 
 

mfbt/Attributes.h

@@ -283,6 +283,35 @@
 #  define MOZ_TSAN_BLACKLIST /* nothing */
 #endif
 
+/**
+ * MOZ_ALLOCATOR tells the compiler that the function it marks returns either a
+ * "fresh", "pointer-free" block of memory, or nullptr. "Fresh" means that the
+ * block is not pointed to by any other reachable pointer in the program.
+ * "Pointer-free" means that the block contains no pointers to any valid object
+ * in the program. It may be initialized with other (non-pointer) values.
+ *
+ * Placing this attribute on appropriate functions helps GCC analyze pointer
+ * aliasing more accurately in their callers.
+ *
+ * GCC warns if a caller ignores the value returned by a function marked with
+ * MOZ_ALLOCATOR: it is hard to imagine cases where dropping the value returned
+ * by a function that meets the criteria above would be intentional.
+ *
+ * Place this attribute after the argument list and 'this' qualifiers of a
+ * function definition. For example, write
+ *
+ *   void *my_allocator(size_t) MOZ_ALLOCATOR;
+ *
+ * or
+ *
+ *   void *my_allocator(size_t bytes) MOZ_ALLOCATOR { ... }
+ */
+#if defined(__GNUC__) || defined(__clang__)
+#  define MOZ_ALLOCATOR __attribute__ ((malloc, warn_unused_result))
+#else
+#  define MOZ_ALLOCATOR
+#endif
+
 #ifdef __cplusplus
 
 /**

xpcom/xpcom-config.h.in

@@ -18,9 +18,6 @@
 /* Define if a dyanmic_cast to void* gives the most derived object */
 #undef HAVE_CPP_DYNAMIC_CAST_TO_VOID_PTR
 
-/* Define to either __attribute__((malloc)) or nothing */
-#undef NS_ATTR_MALLOC
-
 /* Define to either __attribute__((warn_unused_result)) or nothing */
 #undef NS_WARN_UNUSED_RESULT