Re: [PATCH 2/2] gcc-plugins: stackleak: Update for gcc-8

[Alexander Popov <alex.popov@linux.com>]

On 27.02.2018 13:30, Richard Sandiford wrote:
> Laura Abbott <labbott@redhat.com> writes:
>> On 02/24/2018 06:04 AM, Alexander Popov wrote:
>>> Hello Laura,
>>>
>>> Thanks for the cooperation!
>>>
>>> On 23.02.2018 02:14, Laura Abbott wrote:
>>>> +#if BUILDING_GCC_VERSION >= 8000
>>>> +bool check_frame_size()
>>>> +{
>>>> +	return maybe_ge(get_frame_size(), track_frame_size);
>>>
>>> After looking through this guide
>>> https://gcc.gnu.org/onlinedocs//gccint/Guidelines-for-using-poly_005fint.html#Guidelines-for-using-poly_005fint
>>> it seems to me that we should better use something like that:
>>>
>>> poly_int64 frame_size = get_frame_size();
>>>
>>> if (frame_size.to_constant() >= track_frame_size)
>>> 	return 0;
>>>
>>> May I ask for your opinion?
>>>
>>
>> I was a bit wary of using to_constant() because I wasn't 100% sure
>> I could make the assertion that it could actually be a constant so using
> 
> Yeah, the assert would fire for SVE functions that spill SVE registers
> to the stack.
> 
>> maybe_ge seemed like the conservative approach. This also getting into
>> compiler internals so it's possible I'm misunderstanding how poly_ints
>> are supposed to work.
> 
> The maybe_ge patch looks good to me FWIW.

Thanks, Laura and Richard!

I see the rationale, I will use maybe_ge() in the next version of the patch.

Best regards,
Alexander