Re: [PATCH, MPX, 2/X] Pointers Checker [8/25] Languages support

[Ilya Enkovich <enkovich dot gnu at gmail dot com>]

2013/11/5 Richard Biener <richard.guenther@gmail.com>:
> On Tue, Nov 5, 2013 at 2:37 PM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>> 2013/11/5 Richard Biener <richard.guenther@gmail.com>:
>>> On Tue, Nov 5, 2013 at 2:20 PM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>>>> 2013/11/5 Richard Biener <richard.guenther@gmail.com>:
>>>>> On Tue, Nov 5, 2013 at 2:02 PM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>>>>>> 2013/11/4 Richard Biener <richard.guenther@gmail.com>:
>>>>>>> On Thu, Oct 31, 2013 at 10:11 AM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> This patch adds support Pointer Bounds Checker into c-family and LTO front-ends.  The main purpose of changes in front-end is to register all statically initialized objects for checker.  We also need to register such objects created by compiler.
>>>>>>
>>>>>> LTO is quite specific front-end.  For LTO Pointer Bounds Checker
>>>>>> support macro just means it allows instrumented code as input because
>>>>>> all instrumentation is performed before code is streamed out for LTO.
>>>>>
>>>>> But your patch doesn't even make use of the langhook...
>>>>
>>>> Use of langhook is in previous patch
>>>> (http://gcc.gnu.org/ml/gcc-patches/2013-10/msg02408.html). Here is
>>>> it's part:
>>>>
>>>> diff --git a/gcc/toplev.c b/gcc/toplev.c
>>>> index db269b7..0eaf081 100644
>>>> --- a/gcc/toplev.c
>>>> +++ b/gcc/toplev.c
>>>> @@ -1282,6 +1282,15 @@ process_options (void)
>>>>            "and -ftree-loop-linear)");
>>>>  #endif
>>>>
>>>> +  if (flag_check_pointer_bounds)
>>>> +    {
>>>> +      if (targetm.chkp_bound_mode () == VOIDmode)
>>>> +       error ("-fcheck-pointers is not supported for this target");
>>>> +
>>>> +      if (!lang_hooks.chkp_supported)
>>>> +       flag_check_pointer_bounds = 0;
>>>> +    }
>>>> +
>>>>    /* One region RA really helps to decrease the code size.  */
>>>>    if (flag_ira_region == IRA_REGION_AUTODETECT)
>>>>      flag_ira_region
>>>>
>>>> If we try to use -fcheck-pointers -flto for some unsupported language,
>>>> code will not be instrumented.
>>>
>>> What's the reason to have unsupported languages?
>>
>> For some languages (e.g. Java) Pointer Bounds Checker does not make
>> sense at all. Others may require additional support in front-end. The
>> primary target is C family where solved problem is more critical.
>
> What does break if you "enable" it for Java or other "unsupported"
> languages?  That is, if LTO is able to handle a mixed Java and
> C binary then why can Java alone not handle it?

In such case checker will produce useless overhead in Java code.
Resulting code will probably report some bound violations because Java
FE may generate code which seems wrong for Pointer Bounds Checker.

Ilya

>
> Richard.
>
>> Ilya
>>>
>>> Richard.
>>>
>>>> Ilya
>>>>
>>>>>
>>>>> Richard.
>>>>>
>>>>>> Ilya
>>>>>>
>>>>>>>
>>>>>>> You define CHKP as supported in LTO.  That means it has to be supported
>>>>>>> for all languages and thus you should drop the langhook.
>>>>>>>
>>>>>>> Richard.
>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Ilya
>>>>>>>> --
>>>>>>>>
>>>>>>>> gcc/
>>>>>>>>
>>>>>>>> 2013-10-29  Ilya Enkovich  <ilya.enkovich@intel.com>
>>>>>>>>
>>>>>>>>         * c/c-lang.c (LANG_HOOKS_CHKP_SUPPORTED): New.
>>>>>>>>         * cp/cp-lang.c (LANG_HOOKS_CHKP_SUPPORTED): New.
>>>>>>>>         * objc/objc-lang.c (LANG_HOOKS_CHKP_SUPPORTED): New.
>>>>>>>>         * objcp/objcp-lang.c (LANG_HOOKS_CHKP_SUPPORTED): New.
>>>>>>>>         * lto/lto-lang.c (LANG_HOOKS_CHKP_SUPPORTED): New.
>>>>>>>>         * c/c-parser.c (c_parser_declaration_or_fndef): Register statically
>>>>>>>>         initialized decls in Pointer Bounds Checker.
>>>>>>>>         * cp/decl.c (cp_finish_decl): Likewise.
>>>>>>>>         * gimplify.c (gimplify_init_constructor): Likewise.
>>>>>>>>
>>>>>>>>
>>>>>>>> diff --git a/gcc/c/c-lang.c b/gcc/c/c-lang.c
>>>>>>>> index 614c46d..a32bc6b 100644
>>>>>>>> --- a/gcc/c/c-lang.c
>>>>>>>> +++ b/gcc/c/c-lang.c
>>>>>>>> @@ -43,6 +43,8 @@ enum c_language_kind c_language = clk_c;
>>>>>>>>  #define LANG_HOOKS_INIT c_objc_common_init
>>>>>>>>  #undef LANG_HOOKS_INIT_TS
>>>>>>>>  #define LANG_HOOKS_INIT_TS c_common_init_ts
>>>>>>>> +#undef LANG_HOOKS_CHKP_SUPPORTED
>>>>>>>> +#define LANG_HOOKS_CHKP_SUPPORTED true
>>>>>>>>
>>>>>>>>  /* Each front end provides its own lang hook initializer.  */
>>>>>>>>  struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;
>>>>>>>> diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
>>>>>>>> index 9ccae3b..65d83c8 100644
>>>>>>>> --- a/gcc/c/c-parser.c
>>>>>>>> +++ b/gcc/c/c-parser.c
>>>>>>>> @@ -1682,6 +1682,12 @@ c_parser_declaration_or_fndef (c_parser *parser, bool fndef_ok,
>>>>>>>>                   maybe_warn_string_init (TREE_TYPE (d), init);
>>>>>>>>                   finish_decl (d, init_loc, init.value,
>>>>>>>>                                init.original_type, asm_name);
>>>>>>>> +
>>>>>>>> +                 /* Register all decls with initializers in Pointer
>>>>>>>> +                    Bounds Checker to generate required static bounds
>>>>>>>> +                    initializers.  */
>>>>>>>> +                 if (DECL_INITIAL (d) != error_mark_node)
>>>>>>>> +                   chkp_register_var_initializer (d);
>>>>>>>>                 }
>>>>>>>>             }
>>>>>>>>           else
>>>>>>>> diff --git a/gcc/cp/cp-lang.c b/gcc/cp/cp-lang.c
>>>>>>>> index a7fa8e4..6d138bd 100644
>>>>>>>> --- a/gcc/cp/cp-lang.c
>>>>>>>> +++ b/gcc/cp/cp-lang.c
>>>>>>>> @@ -81,6 +81,8 @@ static tree get_template_argument_pack_elems_folded (const_tree);
>>>>>>>>  #define LANG_HOOKS_EH_PERSONALITY cp_eh_personality
>>>>>>>>  #undef LANG_HOOKS_EH_RUNTIME_TYPE
>>>>>>>>  #define LANG_HOOKS_EH_RUNTIME_TYPE build_eh_type_type
>>>>>>>> +#undef LANG_HOOKS_CHKP_SUPPORTED
>>>>>>>> +#define LANG_HOOKS_CHKP_SUPPORTED true
>>>>>>>>
>>>>>>>>  /* Each front end provides its own lang hook initializer.  */
>>>>>>>>  struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;
>>>>>>>> diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
>>>>>>>> index 1e92f2a..db40e75 100644
>>>>>>>> --- a/gcc/cp/decl.c
>>>>>>>> +++ b/gcc/cp/decl.c
>>>>>>>> @@ -6379,6 +6379,12 @@ cp_finish_decl (tree decl, tree init, bool init_const_expr_p,
>>>>>>>>              the class specifier.  */
>>>>>>>>           if (!DECL_EXTERNAL (decl))
>>>>>>>>             var_definition_p = true;
>>>>>>>> +
>>>>>>>> +         /* If var has initilizer then we need to register it in
>>>>>>>> +            Pointer Bounds Checker to generate static bounds initilizer
>>>>>>>> +            if required.  */
>>>>>>>> +         if (DECL_INITIAL (decl) && DECL_INITIAL (decl) != error_mark_node)
>>>>>>>> +           chkp_register_var_initializer (decl);
>>>>>>>>         }
>>>>>>>>        /* If the variable has an array type, lay out the type, even if
>>>>>>>>          there is no initializer.  It is valid to index through the
>>>>>>>> diff --git a/gcc/gimplify.c b/gcc/gimplify.c
>>>>>>>> index 4f52c27..503450f 100644
>>>>>>>> --- a/gcc/gimplify.c
>>>>>>>> +++ b/gcc/gimplify.c
>>>>>>>> @@ -4111,6 +4111,11 @@ gimplify_init_constructor (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
>>>>>>>>
>>>>>>>>                 walk_tree (&ctor, force_labels_r, NULL, NULL);
>>>>>>>>                 ctor = tree_output_constant_def (ctor);
>>>>>>>> +
>>>>>>>> +               /* We need to register created constant object to
>>>>>>>> +                  initialize bounds for pointers in it.  */
>>>>>>>> +               chkp_register_var_initializer (ctor);
>>>>>>>> +
>>>>>>>>                 if (!useless_type_conversion_p (type, TREE_TYPE (ctor)))
>>>>>>>>                   ctor = build1 (VIEW_CONVERT_EXPR, type, ctor);
>>>>>>>>                 TREE_OPERAND (*expr_p, 1) = ctor;
>>>>>>>> diff --git a/gcc/lto/lto-lang.c b/gcc/lto/lto-lang.c
>>>>>>>> index 0fa0fc9..b6073d9 100644
>>>>>>>> --- a/gcc/lto/lto-lang.c
>>>>>>>> +++ b/gcc/lto/lto-lang.c
>>>>>>>> @@ -1278,6 +1278,8 @@ static void lto_init_ts (void)
>>>>>>>>
>>>>>>>>  #undef LANG_HOOKS_INIT_TS
>>>>>>>>  #define LANG_HOOKS_INIT_TS lto_init_ts
>>>>>>>> +#undef LANG_HOOKS_CHKP_SUPPORTED
>>>>>>>> +#define LANG_HOOKS_CHKP_SUPPORTED true
>>>>>>>>
>>>>>>>>  struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;
>>>>>>>>
>>>>>>>> diff --git a/gcc/objc/objc-lang.c b/gcc/objc/objc-lang.c
>>>>>>>> index bc0008b..5e7e43b 100644
>>>>>>>> --- a/gcc/objc/objc-lang.c
>>>>>>>> +++ b/gcc/objc/objc-lang.c
>>>>>>>> @@ -49,6 +49,8 @@ enum c_language_kind c_language = clk_objc;
>>>>>>>>  #define LANG_HOOKS_GIMPLIFY_EXPR objc_gimplify_expr
>>>>>>>>  #undef LANG_HOOKS_INIT_TS
>>>>>>>>  #define LANG_HOOKS_INIT_TS objc_common_init_ts
>>>>>>>> +#undef LANG_HOOKS_CHKP_SUPPORTED
>>>>>>>> +#define LANG_HOOKS_CHKP_SUPPORTED true
>>>>>>>>
>>>>>>>>  /* Each front end provides its own lang hook initializer.  */
>>>>>>>>  struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;
>>>>>>>> diff --git a/gcc/objcp/objcp-lang.c b/gcc/objcp/objcp-lang.c
>>>>>>>> index f9b126f..0bb80eb 100644
>>>>>>>> --- a/gcc/objcp/objcp-lang.c
>>>>>>>> +++ b/gcc/objcp/objcp-lang.c
>>>>>>>> @@ -46,6 +46,8 @@ static void objcxx_init_ts (void);
>>>>>>>>  #define LANG_HOOKS_GIMPLIFY_EXPR objc_gimplify_expr
>>>>>>>>  #undef LANG_HOOKS_INIT_TS
>>>>>>>>  #define LANG_HOOKS_INIT_TS objcxx_init_ts
>>>>>>>> +#undef LANG_HOOKS_CHKP_SUPPORTED
>>>>>>>> +#define LANG_HOOKS_CHKP_SUPPORTED true
>>>>>>>>
>>>>>>>>  /* Each front end provides its own lang hook initializer.  */
>>>>>>>>  struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;