[Mesa-dev] [PATCH 02/12] i965: Add an option to not generate the SIMD8 fragment shader

Ben Widawsky ben at bwidawsk.net
Mon Aug 11 20:08:33 PDT 2014


On Mon, Aug 11, 2014 at 05:29:32PM -0700, Kristian Høgsberg wrote:
> For now, this can only be triggered with a new 'no8' INTEL_DEBUG option
> and a new context flag.  We'll use the context flag later, but introducing
> it now lets us bisect to this commit if it breaks something.
> 
> Signed-off-by: Kristian Høgsberg <krh at bitplanet.net>
> ---
>  src/mesa/drivers/dri/i965/brw_context.h   |  2 ++
>  src/mesa/drivers/dri/i965/brw_fs.cpp      | 14 ++++++++++++--
>  src/mesa/drivers/dri/i965/gen7_wm_state.c |  4 ++--
>  src/mesa/drivers/dri/i965/gen8_ps_state.c |  4 ++--
>  src/mesa/drivers/dri/i965/intel_debug.c   |  1 +
>  src/mesa/drivers/dri/i965/intel_debug.h   |  1 +
>  6 files changed, 20 insertions(+), 6 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
> index 1bbcf46..ab7d858 100644
> --- a/src/mesa/drivers/dri/i965/brw_context.h
> +++ b/src/mesa/drivers/dri/i965/brw_context.h
> @@ -340,6 +340,7 @@ struct brw_wm_prog_data {
>        /** @} */
>     } binding_table;
>  
> +   bool no_8;
>     bool dual_src_blend;
>     bool uses_pos_offset;
>     bool uses_omask;
> @@ -1031,6 +1032,7 @@ struct brw_context
>     bool has_compr4;
>     bool has_negative_rhw_bug;
>     bool has_pln;
> +   bool no_simd8;
>  
>     /**
>      * Some versions of Gen hardware don't do centroid interpolation correctly
> diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
> index bf95b57..061c32d 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
> @@ -3230,15 +3230,25 @@ brw_wm_fs_emit(struct brw_context *brw,
>        }
>     }
>  
> +   exec_list *simd8_instructions;
> +   int no_simd8 = (INTEL_DEBUG & DEBUG_NO8) || brw->no_simd8;
> +   if (no_simd8 && simd16_instructions) {
> +      simd8_instructions = NULL;
> +      prog_data->no_8 = true;
> +   } else {
> +      simd8_instructions = &v.instructions;
> +      prog_data->no_8 = false;
> +   }
> +

Was the fallback to simd8 when !simd16_instructions (and DEBUG_NO8)
intentional? I have no suggestions for what to do in this case, other
than possibly assert. I was just curious.

>     const unsigned *assembly = NULL;
>     if (brw->gen >= 8) {
>        gen8_fs_generator g(brw, mem_ctx, key, prog_data, prog, fp, v.do_dual_src);
> -      assembly = g.generate_assembly(&v.instructions, simd16_instructions,
> +      assembly = g.generate_assembly(simd8_instructions, simd16_instructions,
>                                       final_assembly_size);
>     } else {
>        fs_generator g(brw, mem_ctx, key, prog_data, prog, fp, v.do_dual_src,
>                       v.runtime_check_aads_emit, INTEL_DEBUG & DEBUG_WM);
> -      assembly = g.generate_assembly(&v.instructions, simd16_instructions,
> +      assembly = g.generate_assembly(simd8_instructions, simd16_instructions,
>                                       final_assembly_size);
>     }

Suppose you could combine the two.

>  
> diff --git a/src/mesa/drivers/dri/i965/gen7_wm_state.c b/src/mesa/drivers/dri/i965/gen7_wm_state.c
> index c03d19d..c3e9316 100644
> --- a/src/mesa/drivers/dri/i965/gen7_wm_state.c
> +++ b/src/mesa/drivers/dri/i965/gen7_wm_state.c
> @@ -223,9 +223,9 @@ upload_ps_state(struct brw_context *brw)
>        _mesa_get_min_invocations_per_fragment(ctx, brw->fragment_program, false);
>     assert(min_inv_per_frag >= 1);
>  
> -   if (brw->wm.prog_data->prog_offset_16) {
> +   if (brw->wm.prog_data->prog_offset_16 || brw->wm.prog_data->no_8) {
>        dw4 |= GEN7_PS_16_DISPATCH_ENABLE;
> -      if (min_inv_per_frag == 1) {
> +      if (!brw->wm.prog_data->no_8 && min_inv_per_frag == 1) {
>           dw4 |= GEN7_PS_8_DISPATCH_ENABLE;
>           dw5 |= (brw->wm.prog_data->base.dispatch_grf_start_reg <<
>                   GEN7_PS_DISPATCH_START_GRF_SHIFT_0);

This follows on from the question 2 hunks above, and it looks wrong. If
you don't have 16 wide, but do have no_8, you're setting
GEN7_PS_16_DISPATCH_ENABLE. Probably I've missed something.

> diff --git a/src/mesa/drivers/dri/i965/gen8_ps_state.c b/src/mesa/drivers/dri/i965/gen8_ps_state.c
> index f58d49c..49d4fe0 100644
> --- a/src/mesa/drivers/dri/i965/gen8_ps_state.c
> +++ b/src/mesa/drivers/dri/i965/gen8_ps_state.c
> @@ -195,9 +195,9 @@ upload_ps_state(struct brw_context *brw)
>        _mesa_get_min_invocations_per_fragment(ctx, brw->fragment_program, false);
>     assert(min_invocations_per_fragment >= 1);
>  
> -   if (brw->wm.prog_data->prog_offset_16) {
> +   if (brw->wm.prog_data->prog_offset_16 || brw->wm.prog_data->no_8) {
>        dw6 |= GEN7_PS_16_DISPATCH_ENABLE;
> -      if (min_invocations_per_fragment == 1) {
> +      if (!brw->wm.prog_data->no_8 && min_invocations_per_fragment == 1) {
>           dw6 |= GEN7_PS_8_DISPATCH_ENABLE;
>           dw7 |= (brw->wm.prog_data->base.dispatch_grf_start_reg <<
>                   GEN7_PS_DISPATCH_START_GRF_SHIFT_0);
> diff --git a/src/mesa/drivers/dri/i965/intel_debug.c b/src/mesa/drivers/dri/i965/intel_debug.c
> index c72fce2..1fb8b6c 100644
> --- a/src/mesa/drivers/dri/i965/intel_debug.c
> +++ b/src/mesa/drivers/dri/i965/intel_debug.c
> @@ -66,6 +66,7 @@ static const struct dri_debug_control debug_control[] = {
>     { "nodualobj", DEBUG_NO_DUAL_OBJECT_GS },
>     { "optimizer", DEBUG_OPTIMIZER },
>     { "noann", DEBUG_NO_ANNOTATION },
> +   { "no8",  DEBUG_NO8 },
>     { NULL,    0 }
>  };
>  
> diff --git a/src/mesa/drivers/dri/i965/intel_debug.h b/src/mesa/drivers/dri/i965/intel_debug.h
> index 37dc34a..8e1c299 100644
> --- a/src/mesa/drivers/dri/i965/intel_debug.h
> +++ b/src/mesa/drivers/dri/i965/intel_debug.h
> @@ -62,6 +62,7 @@ extern uint64_t INTEL_DEBUG;
>  #define DEBUG_NO_DUAL_OBJECT_GS 0x80000000
>  #define DEBUG_OPTIMIZER   0x100000000
>  #define DEBUG_NO_ANNOTATION 0x200000000
> +#define DEBUG_NO8        0x40000000
>  
>  #ifdef HAVE_ANDROID_PLATFORM
>  #define LOG_TAG "INTEL-MESA"
> -- 
> 2.0.0
> 
> _______________________________________________
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> mesa-dev at lists.freedesktop.org
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-- 
Ben Widawsky, Intel Open Source Technology Center


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