[Mesa-dev] [PATCH 2/2] i965: Delete linked GLSL IR when using NIR.

[Tapani Pälli]

Huh I see this went in already, I've noticed a problem and thought to 
share it.

Currently program resource list (used by gl api shader queries) is 
generated in linker, before backend LinkShader call. What this means is 
that it relies on frontend optimization passes to get rid of dead inputs 
and outputs. But .. this does not seem to always happen, sometimes these 
get removed only during backend optimization passes. I have a bug on 
this as #90925.

There's 2 possibilities to move with this, either move resource list 
creation to happen after LinkShader (which would mean we should not free 
IR during LinkShader) or try to fix frontend dead code removal to 
recognize the case in the bug. I will keep digging why the variable in 
question is not recognized by the frontend passes, just wanted to let 
you know!


On 06/11/2015 07:40 PM, Jason Ekstrand wrote:
> On Thu, Jun 11, 2015 at 12:41 AM, Tapani Pälli <tapani.palli at intel.com> wrote:
>> This is based on Kenneth's patch to delete 'most of the IR'. Due to
>> linker changes to clone variables, we can now free all of IR.
>>
>> Saves 58MB of memory when replaying a Dota 2 trace on Broadwell.
>
> I think we've saved ~50 MB 3 times now on that one dota trace.  Good work guys!
>
>> Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
>> ---
>>   src/mesa/drivers/dri/i965/brw_shader.cpp | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/mesa/drivers/dri/i965/brw_shader.cpp b/src/mesa/drivers/dri/i965/brw_shader.cpp
>> index 76285f2..99de1cd 100644
>> --- a/src/mesa/drivers/dri/i965/brw_shader.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_shader.cpp
>> @@ -297,8 +297,11 @@ brw_link_shader(struct gl_context *ctx, struct gl_shader_program *shProg)
>>
>>         brw_add_texrect_params(prog);
>>
>> -      if (options->NirOptions)
>> +      if (options->NirOptions) {
>>            prog->nir = brw_create_nir(brw, shProg, prog, (gl_shader_stage) stage);
>> +         ralloc_free(shader->ir);
>> +         shader->ir = NULL;
>> +      }
>>
>>         _mesa_reference_program(ctx, &prog, NULL);
>>      }
>> --
>> 2.1.0
>>
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