[Mesa-dev] [PATCH 1/1] i965: Do not overwrite optimizer dumps

[Jason Ekstrand]

On Wed, Nov 25, 2015 at 10:45 AM, Matt Turner <mattst88 at gmail.com> wrote:
> On Wed, Nov 25, 2015 at 10:37 AM, Jason Ekstrand <jason at jlekstrand.net> wrote:
>> On Wed, Nov 25, 2015 at 10:31 AM, Matt Turner <mattst88 at gmail.com> wrote:
>>> On Wed, Nov 25, 2015 at 4:15 AM, Juan A. Suarez Romero
>>> <jasuarez at igalia.com> wrote:
>>>> When using INTEL_DEBUG=optimizer, each optimizing step is dump to disk,
>>>> in a separate file.
>>>>
>>>> But as fs_visitor::optimize() and vec4_visitor::run() are called more
>>>> than once, it ends up overwriting the files already on disk, loosing
>>>> then previous optimizer steps.
>>>
>>> Huh. I guess this happens when non-orthogonal state changes and we
>>> recompile the program?
>>>
>>> If so, yeah, that would lead to some confusing results.
>>>
>>>> To avoid this, add a new static variable that tracks the global
>>>> iteration across the entire life of the program running.
>>>> ---
>>>>  src/mesa/drivers/dri/i965/brw_fs.cpp   | 13 +++++++++----
>>>>  src/mesa/drivers/dri/i965/brw_vec4.cpp | 11 +++++++----
>>>>  2 files changed, 16 insertions(+), 8 deletions(-)
>>>>
>>>> diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
>>>> index 29f19cc..9520a62 100644
>>>> --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
>>>> +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
>>>> @@ -4947,6 +4947,8 @@ fs_visitor::calculate_register_pressure()
>>>>  void
>>>>  fs_visitor::optimize()
>>>>  {
>>>> +   static int global_iteration = 0;
>>>
>>> I don't know that adding a static variable is the way to solve this. I
>>> know this is debugging code, but using a static variable will make
>>> this thread-unsafe, and I *really* don't want to end up in a situation
>>> where I can't figure out what the optimizer is doing because we were
>>> compiling shaders in parallel...
>>
>> If we really care, we can use an atomic, but meh.  How often are you
>> seriously using INTEL_DEBUG=optimizer on something that's compiling
>> enough shaders in parallel for this to realistically be a problem?  I
>> wouldn't want to dig through that many results.  But, like I said, if
>> it bothers you, make it an atomic.
>
> That doesn't help.

Then what thread-saftey issue are you concerned with here?