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

[Jason Ekstrand]

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.