[Mesa-dev] [PATCH 02/78] i965/nir/vec4: Select between new nir_vec4 or current vec4_visitor code-paths

Eduardo Lima Mitev elima at igalia.com
Mon Jun 29 14:49:38 PDT 2015


On 06/29/2015 11:22 PM, Jason Ekstrand wrote:
> On Fri, Jun 26, 2015 at 1:06 AM, Eduardo Lima Mitev <elima at igalia.com> wrote:
>> The NIR->vec4 pass will be activated if ALL the following conditions are met:
>>
>> * INTEL_USE_NIR environment variable is defined and is positive (1 or true)
>> * The stage is vertex shader
>> * The HW generation is either SandyBridge (gen6), IvyBridge or Haswell (gen7)
> 
> I'm not sure about this last one.  When we did this for FS, it was
> well-known that HSW and IVB were the only ones that were working if
> you used INTEL_USE_NIR on Iron Lake, you got what you got.  This makes
> it easier to develop/test on older platforms because it doesn't
> involve hacking things up.
> 
> Only using it for vertex shaders is perfectly reasonable because there
> are whole chunks of stuff for geometry that simply doesn't exist yet.
> 

Ok, I will drop that condition then, and perhaps spit a warning if gen<6
to alert that NIR->vec4 doesn't yet support that gen, so crashes might
happen.

>>
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89580
>> ---
>>  src/mesa/drivers/dri/i965/brw_program.c  |  5 +++++
>>  src/mesa/drivers/dri/i965/brw_shader.cpp | 14 ++++++++------
>>  src/mesa/drivers/dri/i965/brw_vec4.cpp   | 32 ++++++++++++++++++++++++++++++--
>>  src/mesa/drivers/dri/i965/brw_vec4.h     |  2 ++
>>  4 files changed, 45 insertions(+), 8 deletions(-)
>>
>> diff --git a/src/mesa/drivers/dri/i965/brw_program.c b/src/mesa/drivers/dri/i965/brw_program.c
>> index 2327af7..7e5d23d 100644
>> --- a/src/mesa/drivers/dri/i965/brw_program.c
>> +++ b/src/mesa/drivers/dri/i965/brw_program.c
>> @@ -574,6 +574,11 @@ brw_dump_ir(const char *stage, struct gl_shader_program *shader_prog,
>>              struct gl_shader *shader, struct gl_program *prog)
>>  {
>>     if (shader_prog) {
>> +      /* Since git~104c8fc, shader->ir can be NULL if NIR is used.
>> +       * That must have been checked prior to calling this function, but
>> +       * we double-check here just in case.
>> +       */
>> +      assert(shader->ir != NULL);
>>        fprintf(stderr,
>>                "GLSL IR for native %s shader %d:\n", stage, shader_prog->Name);
>>        _mesa_print_ir(stderr, shader->ir, NULL);
>> diff --git a/src/mesa/drivers/dri/i965/brw_shader.cpp b/src/mesa/drivers/dri/i965/brw_shader.cpp
>> index 5653d6b..0b53647 100644
>> --- a/src/mesa/drivers/dri/i965/brw_shader.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_shader.cpp
>> @@ -118,12 +118,14 @@ brw_compiler_create(void *mem_ctx, const struct brw_device_info *devinfo)
>>     compiler->glsl_compiler_options[MESA_SHADER_VERTEX].OptimizeForAOS = true;
>>     compiler->glsl_compiler_options[MESA_SHADER_GEOMETRY].OptimizeForAOS = true;
>>
>> -   if (compiler->scalar_vs) {
>> -      /* If we're using the scalar backend for vertex shaders, we need to
>> -       * configure these accordingly.
>> -       */
>> -      compiler->glsl_compiler_options[MESA_SHADER_VERTEX].EmitNoIndirectOutput = true;
>> -      compiler->glsl_compiler_options[MESA_SHADER_VERTEX].EmitNoIndirectTemp = true;
>> +   if (compiler->scalar_vs || brw_env_var_as_boolean("INTEL_USE_NIR", false)) {
>> +      if (compiler->scalar_vs) {
>> +         /* If we're using the scalar backend for vertex shaders, we need to
>> +         * configure these accordingly.
>> +         */
>> +         compiler->glsl_compiler_options[MESA_SHADER_VERTEX].EmitNoIndirectOutput = true;
>> +         compiler->glsl_compiler_options[MESA_SHADER_VERTEX].EmitNoIndirectTemp = true;
> 
> This seems wrong.  The vec4 backend can certainly handle indirect
> temporaries and indirect outputs are a must for geometry shaders.  I
> really think we only want to turn these on for scalar shaders.
> 

Actually, these two settings do not get executed for our pass, because
compiler->scalar_vs is still false. Notice the OR in the outer-most if.

What this patch chunk effectively does is to execute the next two lines
below here, for our nir-vec4 pass:

>> +      }
>>        compiler->glsl_compiler_options[MESA_SHADER_VERTEX].OptimizeForAOS = false;
>>
>>        compiler->glsl_compiler_options[MESA_SHADER_VERTEX].NirOptions = nir_options;
>> diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
>> index a5c686c..dcffa04 100644
>> --- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
>> @@ -1707,6 +1707,21 @@ vec4_visitor::emit_shader_time_write(int shader_time_subindex, src_reg value)
>>  }
>>
>>  bool
>> +vec4_visitor::should_use_vec4_nir()
>> +{
>> +   /* NIR->vec4 pass is activated when all these conditions meet:
>> +    *
>> +    * 1) it is a vertex shader
>> +    * 2) INTEL_USE_NIR env-var set to true, so NirOptions are defined for VS
>> +    * 3) hardware gen is SNB, IVB or HSW
>> +    */
>> +   return
>> +      stage == MESA_SHADER_VERTEX &&
>> +      compiler->glsl_compiler_options[MESA_SHADER_VERTEX].NirOptions != NULL &&
>> +      devinfo->gen >= 6 && devinfo->gen < 8;
>> +}
>> +
>> +bool
>>  vec4_visitor::run(gl_clip_plane *clip_planes)
>>  {
>>     sanity_param_count = prog->Parameters->NumParameters;
>> @@ -1722,7 +1737,17 @@ vec4_visitor::run(gl_clip_plane *clip_planes)
>>      * functions called "main").
>>      */
>>     if (shader) {
>> -      visit_instructions(shader->base.ir);
>> +      if (should_use_vec4_nir()) {
>> +         assert(prog->nir != NULL);
>> +         emit_nir_code();
>> +         if (failed)
>> +            return false;
>> +      } else {
>> +         /* Generate VS IR for main().  (the visitor only descends into
>> +          * functions called "main").
>> +          */
>> +         visit_instructions(shader->base.ir);
>> +      }
>>     } else {
>>        emit_program_code();
>>     }
>> @@ -1882,7 +1907,10 @@ brw_vs_emit(struct brw_context *brw,
>>        st_index = brw_get_shader_time_index(brw, prog, &c->vp->program.Base,
>>                                             ST_VS);
>>
>> -   if (unlikely(INTEL_DEBUG & DEBUG_VS))
>> +   /* Since git~104c8fc, shader->base.ir can be NULL if NIR is used,
>> +    * so we need to check that before dumping IR tree.
>> +    */
>> +   if (unlikely(INTEL_DEBUG & DEBUG_VS) && (!prog || shader->base.ir))
>>        brw_dump_ir("vertex", prog, &shader->base, &c->vp->program.Base);
>>
>>     if (brw->intelScreen->compiler->scalar_vs) {
>> diff --git a/src/mesa/drivers/dri/i965/brw_vec4.h b/src/mesa/drivers/dri/i965/brw_vec4.h
>> index 4f2cc86..68bc4ae 100644
>> --- a/src/mesa/drivers/dri/i965/brw_vec4.h
>> +++ b/src/mesa/drivers/dri/i965/brw_vec4.h
>> @@ -389,6 +389,8 @@ public:
>>
>>     void visit_atomic_counter_intrinsic(ir_call *ir);
>>
>> +   virtual bool should_use_vec4_nir();
>> +
>>     virtual void emit_nir_code();
>>     virtual void nir_setup_inputs(nir_shader *shader);
>>     virtual void nir_setup_outputs(nir_shader *shader);
>> --
>> 2.1.4
>>
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>> mesa-dev at lists.freedesktop.org
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> 



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