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


On Mon, Nov 11, 2013 at 3:00 PM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
> 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?

Not to have them easy to lookup in the SSA web.  A long time ago
I proposed to make SSA aggregates possible, so you could do

 tem_2 = __internal_bind_bounds (aggr(D), __bound_tmp.1_3,
__bound_tmp.1_4, ...);
 bar (tem_2);

(originally the SSA aggregates were supposed to make copy-propgagation
possible using the SSA copy propagator, and of course I needed it for
the middle-end array work)

Not sure if that will give other people the creeps (expand would
never expand the "load" from tem_2 but instead handle aggr as
parameter).  A slight complication is due to alias analysis
which would be need to taught that bar performs a load of aggr.

Richard.

>  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


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