Re: [CHKP] Support returned bounds in thunks expand

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

2015-04-02 22:42 GMT+03:00 Jeff Law <law@redhat.com>:
> On 04/02/2015 08:49 AM, Ilya Enkovich wrote:
>>
>> Ping
>>
>> 2015-03-10 13:12 GMT+03:00 Ilya Enkovich <enkovich.gnu@gmail.com>:
>>>
>>> Hi,
>>>
>>> Currentl we loose returned bounds when functions are merged.  This patch
>>> fixes it by adding returne bounds support for cgraph_node::expand_thunk.
>>> Bootstrapped and tested on x86_64-unknown-linux-gnu.  OK for trunk?
>>>
>>> Thanks,
>>> Ilya
>>> --
>>> gcc/
>>>
>>> 2015-03-06  Ilya Enkovich  <ilya.enkovich@intel.com>
>>>
>>>          * cgraphunit.c (cgraph_node::expand_thunk): Build returned
>>>          bounds for instrumented functions.
>>>
>>> gcc/testsuite/
>>>
>>> 2015-03-06  Ilya Enkovich  <ilya.enkovich@intel.com>
>>>
>>>          * gcc/testsuite/gcc.target/i386/thunk-retbnd.c: New.
>
> I really dislike the amount of gimple and bounded pointer knowledge in this
> code.
>
> It seems like a significant modularity violation and while you didn't
> introduce the gimple stuff, we probably shouldn't be making it worse.
>
> Is it possible to let this code build up the thunk, then pass it off as a
> whole to the chkp code to add the instrumentation, particularly for the
> return value?

OK, will rework the patch.

>
> ALso, is this critical for stage4?  It looks like this is strictly a QofI
> change, correct?

Actually having just a tail call in a function we don't lose bounds
and I don't expect it affects QofI. But we get instrumented function
with no returned bounds for a pointer which triggers an assert
somewhere (don't remember exact place). I'll revisit the original
problem and will probably make a simpler stability fix for now,
leaving thunk modification for stage 1.

Thanks,
Ilya

>
> jeff
>