[Mesa-dev] [PATCH 11/11] i965: Use nir_lower_tex for texture coordinate lowering

Jason Ekstrand jason at jlekstrand.net
Mon Nov 16 07:55:17 PST 2015


On Mon, Nov 16, 2015 at 6:27 AM, Iago Toral <itoral at igalia.com> wrote:
> On Mon, 2015-11-16 at 11:33 +0100, Iago Toral wrote:
>> On Wed, 2015-11-11 at 17:26 -0800, Jason Ekstrand wrote:
>> > Previously, we had a rescale_texcoords helper in the FS backend for
>> > handling rescaling of texture coordinates.  Now that we can do variants in
>> > NIR, we can use nir_lower_tex to do the rescaling for us.  This allows us
>> > to delete the i965-specific code and gives us proper TEXTURE_RECTANGLE and
>> > GL_CLAMP handling in vertex and geometry shaders.
>> > ---
>> >  src/mesa/drivers/dri/i965/brw_fs.cpp              |   2 +
>> >  src/mesa/drivers/dri/i965/brw_fs.h                |   3 -
>> >  src/mesa/drivers/dri/i965/brw_fs_nir.cpp          |   4 +-
>> >  src/mesa/drivers/dri/i965/brw_fs_visitor.cpp      | 125 ----------------------
>> >  src/mesa/drivers/dri/i965/brw_nir.c               |  23 ++++
>> >  src/mesa/drivers/dri/i965/brw_nir.h               |   6 ++
>> >  src/mesa/drivers/dri/i965/brw_vec4.cpp            |   2 +
>> >  src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp |   2 +
>> >  8 files changed, 36 insertions(+), 131 deletions(-)
>> >
>> > diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
>> > index b8713ab..c56cafe 100644
>> > --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
>> > +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
>> > @@ -5468,6 +5468,7 @@ brw_compile_fs(const struct brw_compiler *compiler, void *log_data,
>> >                 char **error_str)
>> >  {
>> >     nir_shader *shader = nir_shader_clone(mem_ctx, src_shader);
>> > +   brw_nir_apply_sampler_key(shader, compiler->devinfo, &key->tex, true);
>>
>> This looks like it is part of the post-processing process. In fact, you
>> call this right before brw_postprocess_nir() for every stage. Why not
>> just add a key parameter to brw_postprocess_nir() and call
>> brw_nir_apply_sampler_key from there instead?

Well, right now, brw_nir_apply_sampler_key is used for all stages.
However, if we do more variant stuff in NIR, we'll need to have
brw_nir_apply_vs_key, brw_nir_apply_fs_key, etc. and we can't put it
in postprocess_nir.  I didn't want to join it prematurely.

>> Either way,
>> Reviewed-by: Iago Toral Quiroga <itoral at igalia.com>

Thanks!

>> >     brw_postprocess_nir(shader, compiler->devinfo, true);
>> >
>> >     /* key->alpha_test_func means simulating alpha testing via discards,
>> > @@ -5628,6 +5629,7 @@ brw_compile_cs(const struct brw_compiler *compiler, void *log_data,
>> >                 char **error_str)
>> >  {
>> >     nir_shader *shader = nir_shader_clone(mem_ctx, src_shader);
>> > +   brw_nir_apply_sampler_key(shader, compiler->devinfo, &key->tex, true);
>> >     brw_postprocess_nir(shader, compiler->devinfo, true);
>> >
>> >     prog_data->local_size[0] = shader->info.cs.local_size[0];
>> > diff --git a/src/mesa/drivers/dri/i965/brw_fs.h b/src/mesa/drivers/dri/i965/brw_fs.h
>> > index 2dfcab1..8a181d7 100644
>> > --- a/src/mesa/drivers/dri/i965/brw_fs.h
>> > +++ b/src/mesa/drivers/dri/i965/brw_fs.h
>> > @@ -217,8 +217,6 @@ public:
>> >     void emit_interpolation_setup_gen4();
>> >     void emit_interpolation_setup_gen6();
>> >     void compute_sample_position(fs_reg dst, fs_reg int_sample_pos);
>> > -   fs_reg rescale_texcoord(fs_reg coordinate, int coord_components,
>> > -                           bool is_rect, uint32_t sampler);
>> >     void emit_texture(ir_texture_opcode op,
>> >                       const glsl_type *dest_type,
>> >                       fs_reg coordinate, int components,
>> > @@ -229,7 +227,6 @@ public:
>> >                       fs_reg mcs,
>> >                       int gather_component,
>> >                       bool is_cube_array,
>> > -                     bool is_rect,
>> >                       uint32_t sampler,
>> >                       fs_reg sampler_reg);
>> >     fs_reg emit_mcs_fetch(const fs_reg &coordinate, unsigned components,
>> > diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> > index 02b9f5b..3d83d7c 100644
>> > --- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> > +++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
>> > @@ -2411,8 +2411,6 @@ fs_visitor::nir_emit_texture(const fs_builder &bld, nir_tex_instr *instr)
>> >
>> >     int gather_component = instr->component;
>> >
>> > -   bool is_rect = instr->sampler_dim == GLSL_SAMPLER_DIM_RECT;
>> > -
>> >     bool is_cube_array = instr->sampler_dim == GLSL_SAMPLER_DIM_CUBE &&
>> >                          instr->is_array;
>> >
>> > @@ -2549,7 +2547,7 @@ fs_visitor::nir_emit_texture(const fs_builder &bld, nir_tex_instr *instr)
>> >     emit_texture(op, dest_type, coordinate, instr->coord_components,
>> >                  shadow_comparitor, lod, lod2, lod_components, sample_index,
>> >                  tex_offset, mcs, gather_component,
>> > -                is_cube_array, is_rect, sampler, sampler_reg);
>> > +                is_cube_array, sampler, sampler_reg);
>> >
>> >     fs_reg dest = get_nir_dest(instr->dest);
>> >     dest.type = this->result.type;
>> > diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>> > index 213c912..faf304c 100644
>> > --- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>> > +++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>> > @@ -79,122 +79,6 @@ fs_visitor::emit_vs_system_value(int location)
>> >     return reg;
>> >  }
>> >
>> > -fs_reg
>> > -fs_visitor::rescale_texcoord(fs_reg coordinate, int coord_components,
>> > -                             bool is_rect, uint32_t sampler)
>> > -{
>> > -   bool needs_gl_clamp = true;
>> > -   fs_reg scale_x, scale_y;
>> > -
>> > -   /* The 965 requires the EU to do the normalization of GL rectangle
>> > -    * texture coordinates.  We use the program parameter state
>> > -    * tracking to get the scaling factor.
>> > -    */
>> > -   if (is_rect &&
>> > -       (devinfo->gen < 6 ||
>> > -        (devinfo->gen >= 6 && (key_tex->gl_clamp_mask[0] & (1 << sampler) ||
>> > -                               key_tex->gl_clamp_mask[1] & (1 << sampler))))) {
>> > -      struct gl_program_parameter_list *params = prog->Parameters;
>> > -
>> > -
>> > -      /* FINISHME: We're failing to recompile our programs when the sampler is
>> > -       * updated.  This only matters for the texture rectangle scale
>> > -       * parameters (pre-gen6, or gen6+ with GL_CLAMP).
>> > -       */
>> > -      int tokens[STATE_LENGTH] = {
>> > -    STATE_INTERNAL,
>> > -    STATE_TEXRECT_SCALE,
>> > -    prog->SamplerUnits[sampler],
>> > -    0,
>> > -    0
>> > -      };
>> > -
>> > -      no16("rectangle scale uniform setup not supported on SIMD16\n");
>> > -      if (dispatch_width == 16) {
>> > -    return coordinate;
>> > -      }
>> > -
>> > -      GLuint index = _mesa_add_state_reference(params,
>> > -                                          (gl_state_index *)tokens);
>> > -      /* Try to find existing copies of the texrect scale uniforms. */
>> > -      for (unsigned i = 0; i < uniforms; i++) {
>> > -         if (stage_prog_data->param[i] ==
>> > -             &prog->Parameters->ParameterValues[index][0]) {
>> > -            scale_x = fs_reg(UNIFORM, i);
>> > -            scale_y = fs_reg(UNIFORM, i + 1);
>> > -            break;
>> > -         }
>> > -      }
>> > -
>> > -      /* If we didn't already set them up, do so now. */
>> > -      if (scale_x.file == BAD_FILE) {
>> > -         scale_x = fs_reg(UNIFORM, uniforms);
>> > -         scale_y = fs_reg(UNIFORM, uniforms + 1);
>> > -
>> > -         stage_prog_data->param[uniforms++] =
>> > -            &prog->Parameters->ParameterValues[index][0];
>> > -         stage_prog_data->param[uniforms++] =
>> > -            &prog->Parameters->ParameterValues[index][1];
>> > -      }
>> > -   }
>> > -
>> > -   /* The 965 requires the EU to do the normalization of GL rectangle
>> > -    * texture coordinates.  We use the program parameter state
>> > -    * tracking to get the scaling factor.
>> > -    */
>> > -   if (devinfo->gen < 6 && is_rect) {
>> > -      fs_reg dst = fs_reg(GRF, alloc.allocate(coord_components));
>> > -      fs_reg src = coordinate;
>> > -      coordinate = dst;
>> > -
>> > -      bld.MUL(dst, src, scale_x);
>> > -      dst = offset(dst, bld, 1);
>> > -      src = offset(src, bld, 1);
>> > -      bld.MUL(dst, src, scale_y);
>> > -   } else if (is_rect) {
>> > -      /* On gen6+, the sampler handles the rectangle coordinates
>> > -       * natively, without needing rescaling.  But that means we have
>> > -       * to do GL_CLAMP clamping at the [0, width], [0, height] scale,
>> > -       * not [0, 1] like the default case below.
>> > -       */
>> > -      needs_gl_clamp = false;
>> > -
>> > -      for (int i = 0; i < 2; i++) {
>> > -    if (key_tex->gl_clamp_mask[i] & (1 << sampler)) {
>> > -       fs_reg chan = coordinate;
>> > -       chan = offset(chan, bld, i);
>> > -
>> > -            set_condmod(BRW_CONDITIONAL_GE,
>> > -                        bld.emit(BRW_OPCODE_SEL, chan, chan, fs_reg(0.0f)));
>> > -
>> > -       /* Our parameter comes in as 1.0/width or 1.0/height,
>> > -        * because that's what people normally want for doing
>> > -        * texture rectangle handling.  We need width or height
>> > -        * for clamping, but we don't care enough to make a new
>> > -        * parameter type, so just invert back.
>> > -        */
>> > -       fs_reg limit = vgrf(glsl_type::float_type);
>> > -            bld.MOV(limit, i == 0 ? scale_x : scale_y);
>> > -            bld.emit(SHADER_OPCODE_RCP, limit, limit);
>> > -
>> > -            set_condmod(BRW_CONDITIONAL_L,
>> > -                        bld.emit(BRW_OPCODE_SEL, chan, chan, limit));
>> > -    }
>> > -      }
>> > -   }
>> > -
>> > -   if (coord_components > 0 && needs_gl_clamp) {
>> > -      for (int i = 0; i < MIN2(coord_components, 3); i++) {
>> > -    if (key_tex->gl_clamp_mask[i] & (1 << sampler)) {
>> > -       fs_reg chan = coordinate;
>> > -       chan = offset(chan, bld, i);
>> > -            set_saturate(true, bld.MOV(chan, chan));
>> > -    }
>> > -      }
>> > -   }
>> > -   return coordinate;
>> > -}
>> > -
>> >  /* Sample from the MCS surface attached to this multisample texture. */
>> >  fs_reg
>> >  fs_visitor::emit_mcs_fetch(const fs_reg &coordinate, unsigned components,
>> > @@ -227,7 +111,6 @@ fs_visitor::emit_texture(ir_texture_opcode op,
>> >                           fs_reg mcs,
>> >                           int gather_component,
>> >                           bool is_cube_array,
>> > -                         bool is_rect,
>> >                           uint32_t sampler,
>> >                           fs_reg sampler_reg)
>> >  {
>> > @@ -259,14 +142,6 @@ fs_visitor::emit_texture(ir_texture_opcode op,
>> >        lod = fs_reg(0u);
>> >     }
>> >
>> > -   if (coordinate.file != BAD_FILE) {
>> > -      /* FINISHME: Texture coordinate rescaling doesn't work with non-constant
>> > -       * samplers.  This should only be a problem with GL_CLAMP on Gen7.
>> > -       */
>> > -      coordinate = rescale_texcoord(coordinate, coord_components, is_rect,
>> > -                                    sampler);
>> > -   }
>> > -
>> >     /* Writemasking doesn't eliminate channels on SIMD8 texture
>> >      * samples, so don't worry about them.
>> >      */
>> > diff --git a/src/mesa/drivers/dri/i965/brw_nir.c b/src/mesa/drivers/dri/i965/brw_nir.c
>> > index 693b9cd..3999a60 100644
>> > --- a/src/mesa/drivers/dri/i965/brw_nir.c
>> > +++ b/src/mesa/drivers/dri/i965/brw_nir.c
>> > @@ -395,6 +395,29 @@ brw_create_nir(struct brw_context *brw,
>> >     return nir;
>> >  }
>> >
>> > +void
>> > +brw_nir_apply_sampler_key(nir_shader *nir,
>> > +                          const struct brw_device_info *devinfo,
>> > +                          const struct brw_sampler_prog_key_data *key_tex,
>> > +                          bool is_scalar)
>> > +{
>> > +   nir_lower_tex_options tex_options = { 0 };
>> > +
>> > +   /* Iron Lake and prior require lowering of all rectangle textures */
>> > +   if (devinfo->gen < 6)
>> > +      tex_options.lower_rect = true;
>> > +
>> > +   /* Prior to Broadwell, our hardware can't actually do GL_CLAMP */
>> > +   if (devinfo->gen < 8) {
>> > +      tex_options.saturate_s = key_tex->gl_clamp_mask[0];
>> > +      tex_options.saturate_t = key_tex->gl_clamp_mask[1];
>> > +      tex_options.saturate_r = key_tex->gl_clamp_mask[2];
>> > +   }
>> > +
>> > +   if (nir_lower_tex(nir, &tex_options))
>> > +      nir_optimize(nir, is_scalar);
>
> Based on the code above I guess we only want to execute nir_lower_tex if
> gen < 8 too.

It's a no-op in that case and returns false so it's not a big deal.
The second series uses it to do texture swizzle and that we have to do
on all gens so I didn't see a good reason put it in an if.  I can if
you'd like.  It would be a tad more efficient.  Or, for that matter,
we could make nir_lower_tex early-exit if it has nothing interesting
to do.

> Iago
>
>> > +}
>> > +
>> >  enum brw_reg_type
>> >  brw_type_for_nir_type(nir_alu_type type)
>> >  {
>> > diff --git a/src/mesa/drivers/dri/i965/brw_nir.h b/src/mesa/drivers/dri/i965/brw_nir.h
>> > index 1cdfe00..a399992 100644
>> > --- a/src/mesa/drivers/dri/i965/brw_nir.h
>> > +++ b/src/mesa/drivers/dri/i965/brw_nir.h
>> > @@ -90,6 +90,12 @@ void brw_postprocess_nir(nir_shader *nir,
>> >                           const struct brw_device_info *devinfo,
>> >                           bool is_scalar);
>> >
>> > +
>> > +void brw_nir_apply_sampler_key(nir_shader *nir,
>> > +                               const struct brw_device_info *devinfo,
>> > +                               const struct brw_sampler_prog_key_data *key,
>> > +                               bool is_scalar);
>> > +
>> >  enum brw_reg_type brw_type_for_nir_type(nir_alu_type type);
>> >
>> >  enum glsl_base_type brw_glsl_base_type_for_nir_type(nir_alu_type type);
>> > diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
>> > index 9f75bb6..d207180 100644
>> > --- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
>> > +++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
>> > @@ -2036,6 +2036,8 @@ brw_compile_vs(const struct brw_compiler *compiler, void *log_data,
>> >                 char **error_str)
>> >  {
>> >     nir_shader *shader = nir_shader_clone(mem_ctx, src_shader);
>> > +   brw_nir_apply_sampler_key(shader, compiler->devinfo, &key->tex,
>> > +                             compiler->scalar_vs);
>> >     brw_postprocess_nir(shader, compiler->devinfo, compiler->scalar_vs);
>> >
>> >     const unsigned *assembly = NULL;
>> > diff --git a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
>> > index 92b15d9..4caf54e 100644
>> > --- a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
>> > +++ b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
>> > @@ -616,6 +616,8 @@ brw_compile_gs(const struct brw_compiler *compiler, void *log_data,
>> >     c.key = *key;
>> >
>> >     nir_shader *shader = nir_shader_clone(mem_ctx, src_shader);
>> > +   brw_nir_apply_sampler_key(shader, compiler->devinfo, &key->tex,
>> > +                             compiler->scalar_gs);
>> >     brw_postprocess_nir(shader, compiler->devinfo, compiler->scalar_gs);
>> >
>> >     prog_data->include_primitive_id =
>>
>
>


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