[PATCH] Add no_address_safety_analysis attribute (PR sanitizer/55435)

[Jakub Jelinek <jakub at redhat dot com>]

Hi!

This patch adds the no_address_safety_analysis attribute.  Tested on
x86_64-linux, ok for trunk?

2012-11-22  Jakub Jelinek  <jakub@redhat.com>

	PR sanitizer/55435
	* c-common.c (handle_no_address_safety_analysis_attribute): New
	function.
	(c_common_attribute_table): Add no_address_safety_analysis.

	* asan.c (gate_asan): Don't instrument functions with
	no_address_safety_analysis attribute.
	(gate_asan_O0): Use !optimize && gate_asan ().
	* doc/extend.texi (no_address_safety_analysis): Document new
	function attribute.

	* c-c++-common/asan/attrib-1.c: New test.

--- gcc/c-family/c-common.c.jj	2012-11-19 14:41:10.000000000 +0100
+++ gcc/c-family/c-common.c	2012-11-22 11:51:48.053996443 +0100
@@ -309,6 +309,8 @@ static tree handle_common_attribute (tre
 static tree handle_noreturn_attribute (tree *, tree, tree, int, bool *);
 static tree handle_hot_attribute (tree *, tree, tree, int, bool *);
 static tree handle_cold_attribute (tree *, tree, tree, int, bool *);
+static tree handle_no_address_safety_analysis_attribute (tree *, tree, tree,
+							 int, bool *);
 static tree handle_noinline_attribute (tree *, tree, tree, int, bool *);
 static tree handle_noclone_attribute (tree *, tree, tree, int, bool *);
 static tree handle_leaf_attribute (tree *, tree, tree, int, bool *);
@@ -711,6 +713,10 @@ const struct attribute_spec c_common_att
 			      handle_cold_attribute, false },
   { "hot",                    0, 0, true,  false, false,
 			      handle_hot_attribute, false },
+  { "no_address_safety_analysis",
+			      0, 0, true, false, false,
+			      handle_no_address_safety_analysis_attribute,
+			      false },
   { "warning",		      1, 1, true,  false, false,
 			      handle_error_attribute, false },
   { "error",		      1, 1, true,  false, false,
@@ -6477,6 +6483,22 @@ handle_cold_attribute (tree *node, tree
     {
       warning (OPT_Wattributes, "%qE attribute ignored", name);
       *no_add_attrs = true;
+    }
+
+  return NULL_TREE;
+}
+
+/* Handle a "no_address_safety_analysis" attribute; arguments as in
+   struct attribute_spec.handler.  */
+
+static tree
+handle_no_address_safety_analysis_attribute (tree *node, tree name, tree, int,
+					     bool *no_add_attrs)
+{
+  if (TREE_CODE (*node) != FUNCTION_DECL)
+    {
+      warning (OPT_Wattributes, "%qE attribute ignored", name);
+      *no_add_attrs = true;
     }
 
   return NULL_TREE;
--- gcc/asan.c.jj	2012-11-19 14:41:20.000000000 +0100
+++ gcc/asan.c	2012-11-22 11:35:47.310489415 +0100
@@ -1587,7 +1587,9 @@ asan_instrument (void)
 static bool
 gate_asan (void)
 {
-  return flag_asan != 0;
+  return flag_asan != 0
+	  && !lookup_attribute ("no_address_safety_analysis",
+				DECL_ATTRIBUTES (current_function_decl));
 }
 
 struct gimple_opt_pass pass_asan =
@@ -1614,7 +1616,7 @@ struct gimple_opt_pass pass_asan =
 static bool
 gate_asan_O0 (void)
 {
-  return flag_asan != 0 && !optimize;
+  return !optimize && gate_asan ();
 }
 
 struct gimple_opt_pass pass_asan_O0 =
--- gcc/doc/extend.texi.jj	2012-11-19 14:41:08.000000000 +0100
+++ gcc/doc/extend.texi	2012-11-22 11:52:20.913814831 +0100
@@ -2130,10 +2130,11 @@ attributes are currently defined for fun
 @code{weak}, @code{malloc}, @code{alias}, @code{ifunc},
 @code{warn_unused_result}, @code{nonnull}, @code{gnu_inline},
 @code{externally_visible}, @code{hot}, @code{cold}, @code{artificial},
-@code{error} and @code{warning}.  Several other attributes are defined
-for functions on particular target systems.  Other attributes,
-including @code{section} are supported for variables declarations
-(@pxref{Variable Attributes}) and for types (@pxref{Type Attributes}).
+@code{no_address_safety_analysis}, @code{error} and @code{warning}.
+Several other attributes are defined for functions on particular
+target systems.  Other attributes, including @code{section} are
+supported for variables declarations (@pxref{Variable Attributes})
+and for types (@pxref{Type Attributes}).
 
 GCC plugins may provide their own attributes.
 
@@ -3416,6 +3417,12 @@ with computed goto or @code{asm goto}.
 The @code{cold} attribute on labels is not implemented in GCC versions
 earlier than 4.8.
 
+@item no_address_safety_analysis
+@cindex @code{no_address_safety_analysis} function attribute
+The @code{no_address_safety_analysis} attribute on functions is used
+to inform the compiler that it should not instrument memory accesses
+in the function when compiling with the @option{-fsanitize=address} option.
+
 @item regparm (@var{number})
 @cindex @code{regparm} attribute
 @cindex functions that are passed arguments in registers on the 386
--- gcc/testsuite/c-c++-common/asan/attrib-1.c.jj	2012-11-22 11:43:58.356674747 +0100
+++ gcc/testsuite/c-c++-common/asan/attrib-1.c	2012-11-22 11:59:49.213328881 +0100
@@ -0,0 +1,34 @@
+/* PR sanitizer/55435 */
+/* { dg-do compile } */
+
+__attribute__((no_address_safety_analysis)) int
+f1 (int *p, int *q)
+{
+  *p = 42;
+  return *q;
+}
+
+void f2 (char *);
+void f2 (char *) __attribute__((no_address_safety_analysis));
+void f2 (char *) __attribute__((no_address_safety_analysis));
+void f2 (char *);
+
+void
+f2 (char *p)
+{
+  *p = 42;
+}
+
+void f3 (short *);
+__typeof (f3) f3  __attribute__((__no_address_safety_analysis__));
+
+void
+f3 (short *p)
+{
+  *p = 42;
+}
+
+int v __attribute__((no_address_safety_analysis)); /* { dg-warning "attribute ignored" } */
+
+/* { dg-final { scan-assembler-not "__asan_report_store" } } */
+/* { dg-final { scan-assembler-not "__asan_report_load" } } */

	Jakub