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Diffstat (limited to 'gcc/doc/extend.texi')
| -rw-r--r-- | gcc/doc/extend.texi | 218 |
1 files changed, 6 insertions, 212 deletions
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index d1fbcc39274..da2c63ef00b 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -82,7 +82,6 @@ extensions, accepted by GCC in C90 mode and in C++. * x86 specific memory model extensions for transactional memory:: x86 memory models. * Object Size Checking:: Built-in functions for limited buffer overflow checking. -* Pointer Bounds Checker builtins:: Built-in functions for Pointer Bounds Checker. * Cilk Plus Builtins:: Built-in functions for the Cilk Plus language extension. * Other Builtins:: Other built-in functions. * Target Builtins:: Built-in functions specific to particular targets. @@ -2167,7 +2166,7 @@ attributes are currently defined for functions on all targets: @code{returns_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{bnd_legacy}, +@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 @@ -3611,12 +3610,6 @@ 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 bnd_legacy -@cindex @code{bnd_legacy} function attribute -The @code{bnd_legacy} attribute on functions is used to inform -compiler that function should not be instrumented when compiled -with @option{-fcheck-pointers} option. - @item regparm (@var{number}) @cindex @code{regparm} attribute @cindex functions that are passed arguments in registers on the 386 @@ -5410,12 +5403,12 @@ placed in either the @code{.bss_below100} section or the The keyword @code{__attribute__} allows you to specify special attributes of @code{struct} and @code{union} types when you define such types. This keyword is followed by an attribute specification -inside double parentheses. Eight attributes are currently defined for +inside double parentheses. Seven attributes are currently defined for types: @code{aligned}, @code{packed}, @code{transparent_union}, -@code{unused}, @code{deprecated}, @code{visibility}, @code{may_alias} -and @code{bnd_variable_size}. Other attributes are defined for -functions (@pxref{Function Attributes}) and for variables -(@pxref{Variable Attributes}). +@code{unused}, @code{deprecated}, @code{visibility}, and +@code{may_alias}. Other attributes are defined for functions +(@pxref{Function Attributes}) and for variables (@pxref{Variable +Attributes}). You may also specify any one of these attributes with @samp{__} preceding and following its keyword. This allows you to use these @@ -5707,35 +5700,6 @@ and caught in another, the class must have default visibility. Otherwise the two shared objects are unable to use the same typeinfo node and exception handling will break. -@item bnd_variable_size -When applied to a structure field, this attribute tells Pointer -Bounds Checker that the size of this field should not be computed -using static type information. It may be used to mark variable -sized static array fields placed at the end of a structure. - -@smallexample -struct S -@{ - int size; - char data[1]; -@} -S *p = (S *)malloc (sizeof(S) + 100); -p->data[10] = 0; //Bounds violation -@end smallexample - -By using an attribute for a field we may avoid bound violation -we most probably do not want to see: - -@smallexample -struct S -@{ - int size; - char data[1] __attribute__((bnd_variable_size)); -@} -S *p = (S *)malloc (sizeof(S) + 100); -p->data[10] = 0; //OK -@end smallexample - @end table To specify multiple attributes, separate them by commas within the @@ -7871,176 +7835,6 @@ format string @var{fmt}. If the compiler is able to optimize them to @code{fputc} etc.@: functions, it does, otherwise the checking function is called and the @var{flag} argument passed to it. -@node Pointer Bounds Checker builtins -@section Pointer Bounds Checker Built-in Functions -@findex __builtin___bnd_set_ptr_bounds -@findex __builtin___bnd_narrow_ptr_bounds -@findex __builtin___bnd_copy_ptr_bounds -@findex __builtin___bnd_init_ptr_bounds -@findex __builtin___bnd_null_ptr_bounds -@findex __builtin___bnd_store_ptr_bounds -@findex __builtin___bnd_chk_ptr_lbounds -@findex __builtin___bnd_chk_ptr_ubounds -@findex __builtin___bnd_chk_ptr_bounds -@findex __builtin___bnd_get_ptr_lbound -@findex __builtin___bnd_get_ptr_ubound - -GCC provides a set of built-in functions to control Pointer Bounds Checker -instrumentation. Note that all Pointer Bounds Checker builtins are allowed -to use even if you compile with Pointer Bounds Checker off. But functions -behavior may differ in such case. - -@deftypefn {Built-in Function} void * __builtin___bnd_set_ptr_bounds (const void * @var{q}, size_t @var{size}) - -This built-in function returns a new pointer with the value of @var{q}, and -associate it with the bounds [@var{q}, @var{q}+@var{size}-1]. With Pointer -Bounds Checker off built-in function just returns the first argument. - -@smallexample -extern void *__wrap_malloc (size_t n) -@{ - void *p = (void *)__real_malloc (n); - if (!p) return __builtin___bnd_null_ptr_bounds (p); - return __builtin___bnd_set_ptr_bounds (p, n); -@} -@end smallexample - -@end deftypefn - -@deftypefn {Built-in Function} void * __builtin___bnd_narrow_ptr_bounds (const void * @var{p}, const void * @var{q}, size_t @var{size}) - -This built-in function returns a new pointer with the value of @var{p} -and associate it with the narrowed bounds formed by the intersection -of bounds associated with @var{q} and the [@var{p}, @var{p} + @var{size} - 1]. -With Pointer Bounds Checker off built-in function just returns the first -argument. - -@smallexample -void init_objects (object *objs, size_t size) -@{ - size_t i; - /* Initialize objects one-by-one passing pointers with bounds of an object, - not the full array of objects. */ - for (i = 0; i < size; i++) - init_object (__builtin___bnd_narrow_ptr_bounds (objs + i, objs, sizeof(object))); -@} -@end smallexample - -@end deftypefn - -@deftypefn {Built-in Function} void * __builtin___bnd_copy_ptr_bounds (const void * @var{q}, const void * @var{r}) - -This built-in function returns a new pointer with the value of @var{q}, -and associate it with the bounds already associated with pointer @var{r}. -With Pointer Bounds Checker off built-in function just returns the first -argument. - -@smallexample -/* Here is a way to get pointer to object's field but - still with the full object's bounds. */ -int *field_ptr = __builtin___bnd_copy_ptr_bounds (&objptr->int_filed, objptr); -@end smallexample - -@end deftypefn - -@deftypefn {Built-in Function} void * __builtin___bnd_init_ptr_bounds (const void * @var{q}) - -This built-in function returns a new pointer with the value of @var{q}, and -associate it with INIT (allowing full memory access) bounds. With Pointer -Bounds Checker off built-in function just returns the first argument. - -@end deftypefn - -@deftypefn {Built-in Function} void * __builtin___bnd_null_ptr_bounds (const void * @var{q}) - -This built-in function returns a new pointer with the value of @var{q}, and -associate it with NULL (allowing no memory access) bounds. With Pointer -Bounds Checker off built-in function just returns the first argument. - -@end deftypefn - -@deftypefn {Built-in Function} void __builtin___bnd_store_ptr_bounds (const void ** @var{ptr_addr}, const void * @var{ptr_val}) - -This built-in function stores the bounds associated with pointer @var{ptr_val} -and location @var{ptr_addr} into Bounds Table. This can be useful to propagate -bounds from legacy code without touching the associated pointer's memory when -pointers were copied as integers. With Pointer Bounds Checker off built-in -function call is ignored. - -@end deftypefn - -@deftypefn {Built-in Function} void __builtin___bnd_chk_ptr_lbounds (const void * @var{q}) - -This built-in function checks if the pointer @var{q} is within the lower -bound of its associated bounds. With Pointer Bounds Checker off built-in -function call is ignored. - -@smallexample -extern void *__wrap_memset (void *dst, int c, size_t len) -@{ - if (len > 0) - @{ - __builtin___bnd_chk_ptr_lbounds (dst); - __builtin___bnd_chk_ptr_ubounds ((char *)dst + len - 1); - __real_memset (dst, c, len); - @} - return dst; -@} -@end smallexample - -@end deftypefn - -@deftypefn {Built-in Function} void __builtin___bnd_chk_ptr_ubounds (const void * @var{q}) - -This built-in function checks if the pointer @var{q} is within the upper -bound of its associated bounds. With Pointer Bounds Checker off built-in -function call is ignored. - -@end deftypefn - -@deftypefn {Built-in Function} void __builtin___bnd_chk_ptr_bounds (const void * @var{q}, size_t @var{size}) - -This built-in function checks if [@var{q}, @var{q} + @var{size} - 1] is within -the lower and upper bounds associated with @var{q}. With Pointer Bounds Checker -off built-in function call is ignored. - -@smallexample -extern void *__wrap_memcpy (void *dst, const void *src, size_t n) -@{ - if (n > 0) - @{ - __bnd_chk_ptr_bounds (dst, n); - __bnd_chk_ptr_bounds (src, n); - __real_memcpy (dst, src, n); - @} - return dst; -@} -@end smallexample - -@end deftypefn - -@deftypefn {Built-in Function} const void * __builtin___bnd_get_ptr_lbound (const void * @var{q}) - -This built-in function returns the lower bound (which is a pointer) associated -with the pointer @var{q}. This is at least useful for debugging using printf. -With Pointer Bounds Checker off built-in function returns 0. - -@smallexample -void *lb = __builtin___bnd_get_ptr_lbound (q); -void *ub = __builtin___bnd_get_ptr_ubound (q); -printf ("q = %p lb(q) = %p ub(q) = %p", q, lb, ub); -@end smallexample - -@end deftypefn - -@deftypefn {Built-in Function} const void * __builtin___bnd_get_ptr_ubound (const void * @var{q}) - -This built-in function returns the upper bound (which is a pointer) associated -with the pointer @var{q}. With Pointer Bounds Checker off built-in function -returns -1. - -@end deftypefn - @node Cilk Plus Builtins @section Cilk Plus C/C++ language extension Built-in Functions. |