[Mesa-dev] [PATCH] i965: Use NIR by default for vertex shaders on GEN8+

[Ian Romanick]

On 05/07/2015 04:50 PM, Jason Ekstrand wrote:
> GLSL IR vs. NIR shader-db results for SIMD8 vertex shaders on Broadwell:
> 
>    total instructions in shared programs: 2724483 -> 2711790 (-0.47%)
>    instructions in affected programs:     1860859 -> 1848166 (-0.68%)
>    helped:                                4387
>    HURT:                                  4758
>    GAINED:                                1499
> 
> The gained programs are ARB vertext programs that were previously going
> through the vec4 backend.  Now that we have prog_to_nir, ARB vertex
> programs can go through the scalar backend so they show up as "gained" in
> the shader-db results.

I thought we already did this... why didn't this happen when NIR became
the default for the FS backend?  And has that reason (assuming there was
one) been resolved?

> ---
>  src/mesa/drivers/dri/i965/brw_context.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
> index fd7420a..8615e5e 100644
> --- a/src/mesa/drivers/dri/i965/brw_context.c
> +++ b/src/mesa/drivers/dri/i965/brw_context.c
> @@ -588,7 +588,7 @@ brw_initialize_context_constants(struct brw_context *brw)
>        ctx->Const.ShaderCompilerOptions[MESA_SHADER_VERTEX].EmitNoIndirectTemp = true;
>        ctx->Const.ShaderCompilerOptions[MESA_SHADER_VERTEX].OptimizeForAOS = false;
>  
> -      if (brw_env_var_as_boolean("INTEL_USE_NIR", false))
> +      if (brw_env_var_as_boolean("INTEL_USE_NIR", true))
>           ctx->Const.ShaderCompilerOptions[MESA_SHADER_VERTEX].NirOptions = &nir_options;
>     }
>