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

[Matt Turner]

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.