Re: [PATCH, MPX, 2/X] Pointers Checker [10/25] Calls copy and verification

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

2013/11/11 Richard Biener <richard.guenther@gmail.com>:
> On Fri, Nov 8, 2013 at 11:03 AM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>> 2013/11/8 Richard Biener <richard.guenther@gmail.com>:
>>> On Thu, Nov 7, 2013 at 7:55 PM, Jeff Law <law@redhat.com> wrote:
>>>> On 11/07/13 04:50, Ilya Enkovich wrote:
>>>>>
>>>>> Hi,
>>>>>
>>>>> Here is an updated patch version.
>>>>
>>>> I think this needs to hold until we have a consensus on what the parameter
>>>> passing looks like for bounded pointers.
>>>
>>> I still think the best thing to do on GIMPLE is
>>>
>>> arg_2 = __builtin_ia32_bnd_arg (arg_1(D));
>>> foo (arg_2);
>>>
>>> that is, make the parameter an implicit pair of {value, bound} where
>>> the bound is determined by the value going through a bound association
>>> builtin.  No extra explicit argument to the calls so arguments match
>>> the fndecl and fntype.  All the complexity is defered to the expander
>>> which can trivially lookup bound arguments via the SSA def (I suppose
>>> it does that anyway now for getting at the explicit bound argument now).
>>>
>>> As far as I can see (well, think), all currently passed bound arguments
>>> are the return value of such builtin already.
>>
>> All bounds are result of different builtin calls. Small example:
>>
>> int *global_p;
>> void foo (int *p)
>> {
>>   int buf[10];
>>   bar (p, buf, global_p);
>> }
>>
>>
>> It is translated into:
>>
>>   __bound_tmp.1_7 = __builtin_ia32_bndmk (&buf, 40);
>>   __bound_tmp.1_6 = __builtin_ia32_arg_bnd (p_3(D)(ab));
>>   global_p.0_2 = global_p;
>>   __bound_tmp.1_8 = __builtin_ia32_bndldx (&global_p, global_p.0_2);
>>   bar (p_3(D)(ab), __bound_tmp.1_6, &buf, __bound_tmp.1_7,
>> global_p.0_2, __bound_tmp.1_8);
>>
>> Bounds binding via calls as you suggest may be done as following:
>>
>>   __bound_tmp.1_7 = __builtin_ia32_bndmk (&buf, 40);
>>   __bound_tmp.1_6 = __builtin_ia32_arg_bnd (p_3(D)(ab));
>>   global_p.0_2 = global_p;
>>   __bound_tmp.1_8 = __builtin_ia32_bndldx (&global_p, global_p.0_2);
>>   _9 = __builtin_bind_bounds (p_3(D)(ab), __bound_tmp.1_6);
>>   _10 = __builtin_bind_bounds (&buf, __bound_tmp.1_7);
>>   _11 = __builtin_bind_bounds (global_p.0_2, __bound_tmp.1_8);
>>   bar (_9, _10, _11);
>>
>> Is it close to what you propose?
>
> Yes.

Is there a way to bind bounds with structures in a similar way?  For
SSA names I may easily find definition and check if it is a binding
builtin call. But for structures it is not possible.  The way I see it
to mark all such args as addressable and load required bounds on
expand pass.

Ilya
>
> Richard.
>
>> Ilya
>>>
>>> Richard.
>>>
>>>
>>>
>>>> Jeff