On Tue, Sep 17, 2013 at 06:34:38PM +0200, Jakub Jelinek wrote:
> On Tue, Sep 17, 2013 at 06:26:52PM +0200, Marek Polacek wrote:
> > Well I wonder too ;) I thought it can't be NULL, and tried this
> >
> > struct C {
> > C() { __builtin_unreachable (); }
> > };
>
> I was more wondering about stuff like:
> int a = (__builtin_unreachable (), 1);
> or similar.
Oh yeah, that would segfault, so I added the check that c_f_d is
non-NULL. Ok now?
2013-09-17 Marek Polacek <pola...@redhat.com>
PR sanitizer/58411
* doc/extend.texi: Document no_sanitize_undefined attribute.
* builtins.c (fold_builtin_0): Don't sanitize function if it has the
no_sanitize_undefined attribute.
c-family/
* c-common.c (handle_no_sanitize_undefined_attribute): New function.
Declare it.
(struct attribute_spec c_common_att): Add no_sanitize_undefined.
cp/
* typeck.c (cp_build_binary_op): Don't sanitize function if it has the
no_sanitize_undefined attribute.
c/
* c-typeck.c (build_binary_op): Don't sanitize function if it has the
no_sanitize_undefined attribute.
testsuite/
* c-c++-common/ubsan/attrib-1.c: New test.
--- gcc/c-family/c-common.c.mp2 2013-09-17 15:55:56.417946667 +0200
+++ gcc/c-family/c-common.c 2013-09-17 15:58:55.905513029 +0200
@@ -311,6 +311,8 @@ static tree handle_no_sanitize_address_a
int, bool *);
static tree handle_no_address_safety_analysis_attribute (tree *, tree, tree,
int, bool *);
+static tree handle_no_sanitize_undefined_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 *);
@@ -722,6 +724,9 @@ const struct attribute_spec c_common_att
{ "no_sanitize_address", 0, 0, true, false, false,
handle_no_sanitize_address_attribute,
false },
+ { "no_sanitize_undefined", 0, 0, true, false, false,
+ handle_no_sanitize_undefined_attribute,
+ false },
{ "warning", 1, 1, true, false, false,
handle_error_attribute, false },
{ "error", 1, 1, true, false, false,
@@ -6575,6 +6580,22 @@ handle_no_address_safety_analysis_attrib
return NULL_TREE;
}
+/* Handle a "no_sanitize_undefined" attribute; arguments as in
+ struct attribute_spec.handler. */
+
+static tree
+handle_no_sanitize_undefined_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;
+}
+
/* Handle a "noinline" attribute; arguments as in
struct attribute_spec.handler. */
--- gcc/doc/extend.texi.mp2 2013-09-17 15:55:44.250907707 +0200
+++ gcc/doc/extend.texi 2013-09-17 16:06:21.439974916 +0200
@@ -2136,6 +2136,7 @@ attributes are currently defined for fun
@code{warn_unused_result}, @code{nonnull}, @code{gnu_inline},
@code{externally_visible}, @code{hot}, @code{cold}, @code{artificial},
@code{no_sanitize_address}, @code{no_address_safety_analysis},
+@code{no_sanitize_undefined},
@code{error} and @code{warning}.
Several other attributes are defined for functions on particular
target systems. Other attributes, including @code{section} are
@@ -3500,6 +3501,12 @@ The @code{no_address_safety_analysis} is
@code{no_sanitize_address} attribute, new code should use
@code{no_sanitize_address}.
+@item no_sanitize_undefined
+@cindex @code{no_sanitize_undefined} function attribute
+The @code{no_sanitize_undefined} attribute on functions is used
+to inform the compiler that it should not check for undefined behavior
+in the function when compiling with the @option{-fsanitize=undefined} option.
+
@item regparm (@var{number})
@cindex @code{regparm} attribute
@cindex functions that are passed arguments in registers on the 386
--- gcc/cp/typeck.c.mp2 2013-09-17 16:10:49.935644344 +0200
+++ gcc/cp/typeck.c 2013-09-17 16:11:20.601743694 +0200
@@ -4887,6 +4887,8 @@ cp_build_binary_op (location_t location,
if ((flag_sanitize & SANITIZE_UNDEFINED)
&& !processing_template_decl
&& current_function_decl != 0
+ && !lookup_attribute ("no_sanitize_undefined",
+ DECL_ATTRIBUTES (current_function_decl))
&& (doing_div_or_mod || doing_shift))
{
/* OP0 and/or OP1 might have side-effects. */
--- gcc/c/c-typeck.c.mp2 2013-09-17 16:09:31.423381687 +0200
+++ gcc/c/c-typeck.c 2013-09-17 16:10:00.626476422 +0200
@@ -10498,6 +10498,8 @@ build_binary_op (location_t location, en
if (flag_sanitize & SANITIZE_UNDEFINED
&& current_function_decl != 0
+ && !lookup_attribute ("no_sanitize_undefined",
+ DECL_ATTRIBUTES (current_function_decl))
&& (doing_div_or_mod || doing_shift))
{
/* OP0 and/or OP1 might have side-effects. */
--- gcc/testsuite/c-c++-common/ubsan/attrib-1.c.mp2 2013-09-17
16:33:46.729660165 +0200
+++ gcc/testsuite/c-c++-common/ubsan/attrib-1.c 2013-09-17 16:43:22.308566840
+0200
@@ -0,0 +1,33 @@
+/* PR sanitizer/58411 */
+/* { dg-do compile } */
+/* { dg-options "-fsanitize=undefined -w" } */
+
+__attribute__((no_sanitize_undefined)) int
+f1 (int i)
+{
+ return 16 << i;
+}
+
+int f2 (int i);
+int f2 (int i) __attribute__((no_sanitize_undefined));
+int f2 (int i) __attribute__((no_sanitize_undefined));
+int f2 (int i);
+
+int
+f2 (int i)
+{
+ return 1 / i;
+}
+
+void f3 (void);
+__typeof (f3) f3 __attribute__((__no_sanitize_undefined__));
+
+void
+f3 (void)
+{
+ __builtin_unreachable ();
+}
+
+/* { dg-final { scan-assembler-not "__ubsan_handle_shift_out_of_bounds" } } */
+/* { dg-final { scan-assembler-not "__ubsan_handle_divrem_overflow" } } */
+/* { dg-final { scan-assembler-not "__ubsan_handle_builtin_unreachable" } } */
--- gcc/builtins.c.mp2 2013-09-17 16:13:26.623161281 +0200
+++ gcc/builtins.c 2013-09-17 18:42:11.338273135 +0200
@@ -10313,7 +10313,10 @@ fold_builtin_0 (location_t loc, tree fnd
return fold_builtin_classify_type (NULL_TREE);
case BUILT_IN_UNREACHABLE:
- if (flag_sanitize & SANITIZE_UNREACHABLE)
+ if (flag_sanitize & SANITIZE_UNREACHABLE
+ && current_function_decl != 0
+ && !lookup_attribute ("no_sanitize_undefined",
+ DECL_ATTRIBUTES (current_function_decl)))
return ubsan_instrument_unreachable (loc);
break;
Marek
