path: root/src/mesa/drivers/dri/i965/brw_wm.c

/*
 * Copyright (C) Intel Corp.  2006.  All Rights Reserved.
 * Intel funded Tungsten Graphics to
 * develop this 3D driver.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial
 * portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
#include "brw_context.h"
#include "brw_wm.h"
#include "brw_state.h"
#include "brw_shader.h"
#include "main/enums.h"
#include "main/formats.h"
#include "main/fbobject.h"
#include "main/samplerobj.h"
#include "main/framebuffer.h"
#include "program/prog_parameter.h"
#include "program/program.h"
#include "intel_mipmap_tree.h"
#include "brw_nir.h"

#include "util/ralloc.h"

/**
 * Return a bitfield where bit n is set if barycentric interpolation mode n
 * (see enum brw_wm_barycentric_interp_mode) is needed by the fragment shader.
 */
static unsigned
brw_compute_barycentric_interp_modes(const struct brw_device_info *devinfo,
                                     bool shade_model_flat,
                                     bool persample_shading,
                                     nir_shader *shader)
{
   unsigned barycentric_interp_modes = 0;

   nir_foreach_variable(var, &shader->inputs) {
      enum glsl_interp_qualifier interp_qualifier = var->data.interpolation;
      bool is_centroid = var->data.centroid && !persample_shading;
      bool is_sample = var->data.sample || persample_shading;
      bool is_gl_Color = (var->data.location == VARYING_SLOT_COL0) ||
                         (var->data.location == VARYING_SLOT_COL1);

      /* Ignore WPOS and FACE, because they don't require interpolation. */
      if (var->data.location == VARYING_SLOT_POS ||
          var->data.location == VARYING_SLOT_FACE)
         continue;

      /* Determine the set (or sets) of barycentric coordinates needed to
       * interpolate this variable.  Note that when
       * brw->needs_unlit_centroid_workaround is set, centroid interpolation
       * uses PIXEL interpolation for unlit pixels and CENTROID interpolation
       * for lit pixels, so we need both sets of barycentric coordinates.
       */
      if (interp_qualifier == INTERP_QUALIFIER_NOPERSPECTIVE) {
         if (is_centroid) {
            barycentric_interp_modes |=
               1 << BRW_WM_NONPERSPECTIVE_CENTROID_BARYCENTRIC;
         } else if (is_sample) {
            barycentric_interp_modes |=
               1 << BRW_WM_NONPERSPECTIVE_SAMPLE_BARYCENTRIC;
         }
         if ((!is_centroid && !is_sample) ||
             devinfo->needs_unlit_centroid_workaround) {
            barycentric_interp_modes |=
               1 << BRW_WM_NONPERSPECTIVE_PIXEL_BARYCENTRIC;
         }
      } else if (interp_qualifier == INTERP_QUALIFIER_SMOOTH ||
                 (!(shade_model_flat && is_gl_Color) &&
                  interp_qualifier == INTERP_QUALIFIER_NONE)) {
         if (is_centroid) {
            barycentric_interp_modes |=
               1 << BRW_WM_PERSPECTIVE_CENTROID_BARYCENTRIC;
         } else if (is_sample) {
            barycentric_interp_modes |=
               1 << BRW_WM_PERSPECTIVE_SAMPLE_BARYCENTRIC;
         }
         if ((!is_centroid && !is_sample) ||
             devinfo->needs_unlit_centroid_workaround) {
            barycentric_interp_modes |=
               1 << BRW_WM_PERSPECTIVE_PIXEL_BARYCENTRIC;
         }
      }
   }

   return barycentric_interp_modes;
}

static uint8_t
computed_depth_mode(struct gl_fragment_program *fp)
{
   if (fp->Base.OutputsWritten & BITFIELD64_BIT(FRAG_RESULT_DEPTH)) {
      switch (fp->FragDepthLayout) {
      case FRAG_DEPTH_LAYOUT_NONE:
      case FRAG_DEPTH_LAYOUT_ANY:
         return BRW_PSCDEPTH_ON;
      case FRAG_DEPTH_LAYOUT_GREATER:
         return BRW_PSCDEPTH_ON_GE;
      case FRAG_DEPTH_LAYOUT_LESS:
         return BRW_PSCDEPTH_ON_LE;
      case FRAG_DEPTH_LAYOUT_UNCHANGED:
         return BRW_PSCDEPTH_OFF;
      }
   }
   return BRW_PSCDEPTH_OFF;
}

static void
assign_fs_binding_table_offsets(const struct brw_device_info *devinfo,
                                const struct gl_shader_program *shader_prog,
                                const struct gl_program *prog,
                                const struct brw_wm_prog_key *key,
                                struct brw_wm_prog_data *prog_data)
{
   uint32_t next_binding_table_offset = 0;

   /* If there are no color regions, we still perform an FB write to a null
    * renderbuffer, which we place at surface index 0.
    */
   prog_data->binding_table.render_target_start = next_binding_table_offset;
   next_binding_table_offset += MAX2(key->nr_color_regions, 1);

   brw_assign_common_binding_table_offsets(MESA_SHADER_FRAGMENT, devinfo,
                                           shader_prog, prog, &prog_data->base,
                                           next_binding_table_offset);
}

/**
 * All Mesa program -> GPU code generation goes through this function.
 * Depending on the instructions used (i.e. flow control instructions)
 * we'll use one of two code generators.
 */
bool
brw_codegen_wm_prog(struct brw_context *brw,
                    struct gl_shader_program *prog,
                    struct brw_fragment_program *fp,
                    struct brw_wm_prog_key *key)
{
   struct gl_context *ctx = &brw->ctx;
   void *mem_ctx = ralloc_context(NULL);
   struct brw_wm_prog_data prog_data;
   const GLuint *program;
   struct brw_shader *fs = NULL;
   GLuint program_size;
   bool start_busy = false;
   double start_time = 0;

   if (prog)
      fs = (struct brw_shader *)prog->_LinkedShaders[MESA_SHADER_FRAGMENT];

   memset(&prog_data, 0, sizeof(prog_data));
   /* key->alpha_test_func means simulating alpha testing via discards,
    * so the shader definitely kills pixels.
    */
   prog_data.uses_kill = fp->program.UsesKill || key->alpha_test_func;
   prog_data.uses_omask =
      fp->program.Base.OutputsWritten & BITFIELD64_BIT(FRAG_RESULT_SAMPLE_MASK);
   prog_data.computed_depth_mode = computed_depth_mode(&fp->program);

   prog_data.early_fragment_tests = fs && fs->base.EarlyFragmentTests;

   /* Use ALT floating point mode for ARB programs so that 0^0 == 1. */
   if (!prog)
      prog_data.base.use_alt_mode = true;

   assign_fs_binding_table_offsets(brw->intelScreen->devinfo, prog,
                                   &fp->program.Base, key, &prog_data);

   /* Allocate the references to the uniforms that will end up in the
    * prog_data associated with the compiled program, and which will be freed
    * by the state cache.
    */
   int param_count = fp->program.Base.nir->num_uniforms;
   if (fs)
      prog_data.base.nr_image_params = fs->base.NumImages;
   /* The backend also sometimes adds params for texture size. */
   param_count += 2 * ctx->Const.Program[MESA_SHADER_FRAGMENT].MaxTextureImageUnits;
   prog_data.base.param =
      rzalloc_array(NULL, const gl_constant_value *, param_count);
   prog_data.base.pull_param =
      rzalloc_array(NULL, const gl_constant_value *, param_count);
   prog_data.base.image_param =
      rzalloc_array(NULL, struct brw_image_param,
                    prog_data.base.nr_image_params);
   prog_data.base.nr_params = param_count;

   if (prog) {
      brw_nir_setup_glsl_uniforms(fp->program.Base.nir, prog, &fp->program.Base,
                                  &prog_data.base, true);
   } else {
      brw_nir_setup_arb_uniforms(fp->program.Base.nir, &fp->program.Base,
                                 &prog_data.base);
   }

   prog_data.barycentric_interp_modes =
      brw_compute_barycentric_interp_modes(brw->intelScreen->devinfo,
                                           key->flat_shade,
                                           key->persample_shading,
                                           fp->program.Base.nir);

   if (unlikely(brw->perf_debug)) {
      start_busy = (brw->batch.last_bo &&
                    drm_intel_bo_busy(brw->batch.last_bo));
      start_time = get_time();
   }

   program = brw_wm_fs_emit(brw, mem_ctx, key, &prog_data,
                            &fp->program, prog, &program_size);
   if (program == NULL) {
      ralloc_free(mem_ctx);
      return false;
   }

   if (unlikely(brw->perf_debug) && fs) {
      if (fs->compiled_once)
         brw_wm_debug_recompile(brw, prog, key);
      fs->compiled_once = true;

      if (start_busy && !drm_intel_bo_busy(brw->batch.last_bo)) {
         perf_debug("FS compile took %.03f ms and stalled the GPU\n",
                    (get_time() - start_time) * 1000);
      }
   }

   if (prog_data.base.total_scratch) {
      brw_get_scratch_bo(brw, &brw->wm.base.scratch_bo,
			 prog_data.base.total_scratch * brw->max_wm_threads);
   }

   if (unlikely(INTEL_DEBUG & DEBUG_WM))
      fprintf(stderr, "\n");

   brw_upload_cache(&brw->cache, BRW_CACHE_FS_PROG,
		    key, sizeof(struct brw_wm_prog_key),
		    program, program_size,
		    &prog_data, sizeof(prog_data),
		    &brw->wm.base.prog_offset, &brw->wm.prog_data);

   ralloc_free(mem_ctx);

   return true;
}

static bool
key_debug(struct brw_context *brw, const char *name, int a, int b)
{
   if (a != b) {
      perf_debug("  %s %d->%d\n", name, a, b);
      return true;
   } else {
      return false;
   }
}

bool
brw_debug_recompile_sampler_key(struct brw_context *brw,
                                const struct brw_sampler_prog_key_data *old_key,
                                const struct brw_sampler_prog_key_data *key)
{
   bool found = false;

   for (unsigned int i = 0; i < MAX_SAMPLERS; i++) {
      found |= key_debug(brw, "EXT_texture_swizzle or DEPTH_TEXTURE_MODE",
                         old_key->swizzles[i], key->swizzles[i]);
   }
   found |= key_debug(brw, "GL_CLAMP enabled on any texture unit's 1st coordinate",
                      old_key->gl_clamp_mask[0], key->gl_clamp_mask[0]);
   found |= key_debug(brw, "GL_CLAMP enabled on any texture unit's 2nd coordinate",
                      old_key->gl_clamp_mask[1], key->gl_clamp_mask[1]);
   found |= key_debug(brw, "GL_CLAMP enabled on any texture unit's 3rd coordinate",
                      old_key->gl_clamp_mask[2], key->gl_clamp_mask[2]);
   found |= key_debug(brw, "gather channel quirk on any texture unit",
                      old_key->gather_channel_quirk_mask, key->gather_channel_quirk_mask);
   found |= key_debug(brw, "compressed multisample layout",
                      old_key->compressed_multisample_layout_mask,
                      key->compressed_multisample_layout_mask);

   for (unsigned int i = 0; i < MAX_SAMPLERS; i++) {
      found |= key_debug(brw, "textureGather workarounds",
                         old_key->gen6_gather_wa[i], key->gen6_gather_wa[i]);
   }

   return found;
}

void
brw_wm_debug_recompile(struct brw_context *brw,
                       struct gl_shader_program *prog,
                       const struct brw_wm_prog_key *key)
{
   struct brw_cache_item *c = NULL;
   const struct brw_wm_prog_key *old_key = NULL;
   bool found = false;

   perf_debug("Recompiling fragment shader for program %d\n", prog->Name);

   for (unsigned int i = 0; i < brw->cache.size; i++) {
      for (c = brw->cache.items[i]; c; c = c->next) {
         if (c->cache_id == BRW_CACHE_FS_PROG) {
            old_key = c->key;

            if (old_key->program_string_id == key->program_string_id)
               break;
         }
      }
      if (c)
         break;
   }

   if (!c) {
      perf_debug("  Didn't find previous compile in the shader cache for debug\n");
      return;
   }

   found |= key_debug(brw, "alphatest, computed depth, depth test, or "
                      "depth write",
                      old_key->iz_lookup, key->iz_lookup);
   found |= key_debug(brw, "depth statistics",
                      old_key->stats_wm, key->stats_wm);
   found |= key_debug(brw, "flat shading",
                      old_key->flat_shade, key->flat_shade);
   found |= key_debug(brw, "per-sample shading",
                      old_key->persample_shading, key->persample_shading);
   found |= key_debug(brw, "per-sample shading and 2x MSAA",
                      old_key->persample_2x, key->persample_2x);
   found |= key_debug(brw, "number of color buffers",
                      old_key->nr_color_regions, key->nr_color_regions);
   found |= key_debug(brw, "MRT alpha test or alpha-to-coverage",
                      old_key->replicate_alpha, key->replicate_alpha);
   found |= key_debug(brw, "rendering to FBO",
                      old_key->render_to_fbo, key->render_to_fbo);
   found |= key_debug(brw, "fragment color clamping",
                      old_key->clamp_fragment_color, key->clamp_fragment_color);
   found |= key_debug(brw, "line smoothing",
                      old_key->line_aa, key->line_aa);
   found |= key_debug(brw, "renderbuffer height",
                      old_key->drawable_height, key->drawable_height);
   found |= key_debug(brw, "input slots valid",
                      old_key->input_slots_valid, key->input_slots_valid);
   found |= key_debug(brw, "mrt alpha test function",
                      old_key->alpha_test_func, key->alpha_test_func);
   found |= key_debug(brw, "mrt alpha test reference value",
                      old_key->alpha_test_ref, key->alpha_test_ref);

   found |= brw_debug_recompile_sampler_key(brw, &old_key->tex, &key->tex);

   if (!found) {
      perf_debug("  Something else\n");
   }
}

static uint8_t
gen6_gather_workaround(GLenum internalformat)
{
   switch (internalformat) {
   case GL_R8I: return WA_SIGN | WA_8BIT;
   case GL_R8UI: return WA_8BIT;
   case GL_R16I: return WA_SIGN | WA_16BIT;
   case GL_R16UI: return WA_16BIT;
   default:
      /* Note that even though GL_R32I and GL_R32UI have format overrides in
       * the surface state, there is no shader w/a required.
       */
      return 0;
   }
}

void
brw_populate_sampler_prog_key_data(struct gl_context *ctx,
				   const struct gl_program *prog,
                                   unsigned sampler_count,
				   struct brw_sampler_prog_key_data *key)
{
   struct brw_context *brw = brw_context(ctx);

   for (int s = 0; s < sampler_count; s++) {
      key->swizzles[s] = SWIZZLE_NOOP;

      if (!(prog->SamplersUsed & (1 << s)))
	 continue;

      int unit_id = prog->SamplerUnits[s];
      const struct gl_texture_unit *unit = &ctx->Texture.Unit[unit_id];

      if (unit->_Current && unit->_Current->Target != GL_TEXTURE_BUFFER) {
	 const struct gl_texture_object *t = unit->_Current;
	 const struct gl_texture_image *img = t->Image[0][t->BaseLevel];
	 struct gl_sampler_object *sampler = _mesa_get_samplerobj(ctx, unit_id);

         const bool alpha_depth = t->DepthMode == GL_ALPHA &&
            (img->_BaseFormat == GL_DEPTH_COMPONENT ||
             img->_BaseFormat == GL_DEPTH_STENCIL);

         /* Haswell handles texture swizzling as surface format overrides
          * (except for GL_ALPHA); all other platforms need MOVs in the shader.
          */
         if (alpha_depth || (brw->gen < 8 && !brw->is_haswell))
            key->swizzles[s] = brw_get_texture_swizzle(ctx, t);

	 if (brw->gen < 8 &&
             sampler->MinFilter != GL_NEAREST &&
	     sampler->MagFilter != GL_NEAREST) {
	    if (sampler->WrapS == GL_CLAMP)
	       key->gl_clamp_mask[0] |= 1 << s;
	    if (sampler->WrapT == GL_CLAMP)
	       key->gl_clamp_mask[1] |= 1 << s;
	    if (sampler->WrapR == GL_CLAMP)
	       key->gl_clamp_mask[2] |= 1 << s;
	 }

         /* gather4's channel select for green from RG32F is broken; requires
          * a shader w/a on IVB; fixable with just SCS on HSW.
          */
         if (brw->gen == 7 && !brw->is_haswell && prog->UsesGather) {
            if (img->InternalFormat == GL_RG32F)
               key->gather_channel_quirk_mask |= 1 << s;
         }

         /* Gen6's gather4 is broken for UINT/SINT; we treat them as
          * UNORM/FLOAT instead and fix it in the shader.
          */
         if (brw->gen == 6 && prog->UsesGather) {
            key->gen6_gather_wa[s] = gen6_gather_workaround(img->InternalFormat);
         }

         /* If this is a multisample sampler, and uses the CMS MSAA layout,
          * then we need to emit slightly different code to first sample the
          * MCS surface.
          */
         struct intel_texture_object *intel_tex =
            intel_texture_object((struct gl_texture_object *)t);

         if (brw->gen >= 7 &&
             intel_tex->mt->msaa_layout == INTEL_MSAA_LAYOUT_CMS) {
            key->compressed_multisample_layout_mask |= 1 << s;
         }
      }
   }
}

static bool
brw_wm_state_dirty (struct brw_context *brw)
{
   return brw_state_dirty(brw,
                          _NEW_BUFFERS |
                          _NEW_COLOR |
                          _NEW_DEPTH |
                          _NEW_FRAG_CLAMP |
                          _NEW_HINT |
                          _NEW_LIGHT |
                          _NEW_LINE |
                          _NEW_MULTISAMPLE |
                          _NEW_POLYGON |
                          _NEW_STENCIL |
                          _NEW_TEXTURE,
                          BRW_NEW_FRAGMENT_PROGRAM |
                          BRW_NEW_REDUCED_PRIMITIVE |
                          BRW_NEW_STATS_WM |
                          BRW_NEW_VUE_MAP_GEOM_OUT);
}

static void
brw_wm_populate_key(struct brw_context *brw, struct brw_wm_prog_key *key)
{
   struct gl_context *ctx = &brw->ctx;
   /* BRW_NEW_FRAGMENT_PROGRAM */
   const struct brw_fragment_program *fp =
      (struct brw_fragment_program *) brw->fragment_program;
   const struct gl_program *prog = (struct gl_program *) brw->fragment_program;
   GLuint lookup = 0;
   GLuint line_aa;
   bool program_uses_dfdy = fp->program.UsesDFdy;
   const bool multisample_fbo = _mesa_geometric_samples(ctx->DrawBuffer) > 1;

   memset(key, 0, sizeof(*key));

   /* Build the index for table lookup
    */
   if (brw->gen < 6) {
      /* _NEW_COLOR */
      if (fp->program.UsesKill || ctx->Color.AlphaEnabled)
	 lookup |= IZ_PS_KILL_ALPHATEST_BIT;

      if (fp->program.Base.OutputsWritten & BITFIELD64_BIT(FRAG_RESULT_DEPTH))
	 lookup |= IZ_PS_COMPUTES_DEPTH_BIT;

      /* _NEW_DEPTH */
      if (ctx->Depth.Test)
	 lookup |= IZ_DEPTH_TEST_ENABLE_BIT;

      if (ctx->Depth.Test && ctx->Depth.Mask) /* ?? */
	 lookup |= IZ_DEPTH_WRITE_ENABLE_BIT;

      /* _NEW_STENCIL | _NEW_BUFFERS */
      if (ctx->Stencil._Enabled) {
	 lookup |= IZ_STENCIL_TEST_ENABLE_BIT;

	 if (ctx->Stencil.WriteMask[0] ||
	     ctx->Stencil.WriteMask[ctx->Stencil._BackFace])
	    lookup |= IZ_STENCIL_WRITE_ENABLE_BIT;
      }
      key->iz_lookup = lookup;
   }

   line_aa = AA_NEVER;

   /* _NEW_LINE, _NEW_POLYGON, BRW_NEW_REDUCED_PRIMITIVE */
   if (ctx->Line.SmoothFlag) {
      if (brw->reduced_primitive == GL_LINES) {
	 line_aa = AA_ALWAYS;
      }
      else if (brw->reduced_primitive == GL_TRIANGLES) {
	 if (ctx->Polygon.FrontMode == GL_LINE) {
	    line_aa = AA_SOMETIMES;

	    if (ctx->Polygon.BackMode == GL_LINE ||
		(ctx->Polygon.CullFlag &&
		 ctx->Polygon.CullFaceMode == GL_BACK))
	       line_aa = AA_ALWAYS;
	 }
	 else if (ctx->Polygon.BackMode == GL_LINE) {
	    line_aa = AA_SOMETIMES;

	    if ((ctx->Polygon.CullFlag &&
		 ctx->Polygon.CullFaceMode == GL_FRONT))
	       line_aa = AA_ALWAYS;
	 }
      }
   }

   key->line_aa = line_aa;

   /* _NEW_HINT */
   key->high_quality_derivatives =
      ctx->Hint.FragmentShaderDerivative == GL_NICEST;

   if (brw->gen < 6)
      key->stats_wm = brw->stats_wm;

   /* _NEW_LIGHT */
   key->flat_shade = (ctx->Light.ShadeModel == GL_FLAT);

   /* _NEW_FRAG_CLAMP | _NEW_BUFFERS */
   key->clamp_fragment_color = ctx->Color._ClampFragmentColor;

   /* _NEW_TEXTURE */
   brw_populate_sampler_prog_key_data(ctx, prog, brw->wm.base.sampler_count,
                                      &key->tex);

   /* _NEW_BUFFERS */
   /*
    * Include the draw buffer origin and height so that we can calculate
    * fragment position values relative to the bottom left of the drawable,
    * from the incoming screen origin relative position we get as part of our
    * payload.
    *
    * This is only needed for the WM_WPOSXY opcode when the fragment program
    * uses the gl_FragCoord input.
    *
    * We could avoid recompiling by including this as a constant referenced by
    * our program, but if we were to do that it would also be nice to handle
    * getting that constant updated at batchbuffer submit time (when we
    * hold the lock and know where the buffer really is) rather than at emit
    * time when we don't hold the lock and are just guessing.  We could also
    * just avoid using this as key data if the program doesn't use
    * fragment.position.
    *
    * For DRI2 the origin_x/y will always be (0,0) but we still need the
    * drawable height in order to invert the Y axis.
    */
   if (fp->program.Base.InputsRead & VARYING_BIT_POS) {
      key->drawable_height = _mesa_geometric_height(ctx->DrawBuffer);
   }

   if ((fp->program.Base.InputsRead & VARYING_BIT_POS) || program_uses_dfdy) {
      key->render_to_fbo = _mesa_is_user_fbo(ctx->DrawBuffer);
   }

   /* _NEW_BUFFERS */
   key->nr_color_regions = ctx->DrawBuffer->_NumColorDrawBuffers;

   /* _NEW_MULTISAMPLE, _NEW_COLOR, _NEW_BUFFERS */
   key->replicate_alpha = ctx->DrawBuffer->_NumColorDrawBuffers > 1 &&
      (ctx->Multisample.SampleAlphaToCoverage || ctx->Color.AlphaEnabled);

   /* _NEW_BUFFERS _NEW_MULTISAMPLE */
   /* Ignore sample qualifier while computing this flag. */
   key->persample_shading =
      _mesa_get_min_invocations_per_fragment(ctx, &fp->program, true) > 1;
   if (key->persample_shading)
      key->persample_2x = _mesa_geometric_samples(ctx->DrawBuffer) == 2;

   key->compute_pos_offset =
      _mesa_get_min_invocations_per_fragment(ctx, &fp->program, false) > 1 &&
      fp->program.Base.SystemValuesRead & SYSTEM_BIT_SAMPLE_POS;

   key->compute_sample_id =
      multisample_fbo &&
      ctx->Multisample.Enabled &&
      (fp->program.Base.SystemValuesRead & SYSTEM_BIT_SAMPLE_ID);

   /* BRW_NEW_VUE_MAP_GEOM_OUT */
   if (brw->gen < 6 || _mesa_bitcount_64(fp->program.Base.InputsRead &
                                         BRW_FS_VARYING_INPUT_MASK) > 16)
      key->input_slots_valid = brw->vue_map_geom_out.slots_valid;


   /* _NEW_COLOR | _NEW_BUFFERS */
   /* Pre-gen6, the hardware alpha test always used each render
    * target's alpha to do alpha test, as opposed to render target 0's alpha
    * like GL requires.  Fix that by building the alpha test into the
    * shader, and we'll skip enabling the fixed function alpha test.
    */
   if (brw->gen < 6 && ctx->DrawBuffer->_NumColorDrawBuffers > 1 &&
       ctx->Color.AlphaEnabled) {
      key->alpha_test_func = ctx->Color.AlphaFunc;
      key->alpha_test_ref = ctx->Color.AlphaRef;
   }

   /* The unique fragment program ID */
   key->program_string_id = fp->id;
}

void
brw_upload_wm_prog(struct brw_context *brw)
{
   struct gl_context *ctx = &brw->ctx;
   struct gl_shader_program *current = ctx->_Shader->_CurrentFragmentProgram;
   struct brw_wm_prog_key key;
   struct brw_fragment_program *fp = (struct brw_fragment_program *)
      brw->fragment_program;

   if (!brw_wm_state_dirty(brw))
      return;

   brw_wm_populate_key(brw, &key);

   if (!brw_search_cache(&brw->cache, BRW_CACHE_FS_PROG,
			 &key, sizeof(key),
			 &brw->wm.base.prog_offset, &brw->wm.prog_data)) {
      bool success = brw_codegen_wm_prog(brw, current, fp, &key);
      (void) success;
      assert(success);
   }
   brw->wm.base.prog_data = &brw->wm.prog_data->base;
}

bool
brw_fs_precompile(struct gl_context *ctx,
                  struct gl_shader_program *shader_prog,
                  struct gl_program *prog)
{
   struct brw_context *brw = brw_context(ctx);
   struct brw_wm_prog_key key;

   struct gl_fragment_program *fp = (struct gl_fragment_program *) prog;
   struct brw_fragment_program *bfp = brw_fragment_program(fp);
   bool program_uses_dfdy = fp->UsesDFdy;

   memset(&key, 0, sizeof(key));

   if (brw->gen < 6) {
      if (fp->UsesKill)
         key.iz_lookup |= IZ_PS_KILL_ALPHATEST_BIT;

      if (fp->Base.OutputsWritten & BITFIELD64_BIT(FRAG_RESULT_DEPTH))
         key.iz_lookup |= IZ_PS_COMPUTES_DEPTH_BIT;

      /* Just assume depth testing. */
      key.iz_lookup |= IZ_DEPTH_TEST_ENABLE_BIT;
      key.iz_lookup |= IZ_DEPTH_WRITE_ENABLE_BIT;
   }

   if (brw->gen < 6 || _mesa_bitcount_64(fp->Base.InputsRead &
                                         BRW_FS_VARYING_INPUT_MASK) > 16)
      key.input_slots_valid = fp->Base.InputsRead | VARYING_BIT_POS;

   brw_setup_tex_for_precompile(brw, &key.tex, &fp->Base);

   if (fp->Base.InputsRead & VARYING_BIT_POS) {
      key.drawable_height = ctx->DrawBuffer->Height;
   }

   key.nr_color_regions = _mesa_bitcount_64(fp->Base.OutputsWritten &
         ~(BITFIELD64_BIT(FRAG_RESULT_DEPTH) |
         BITFIELD64_BIT(FRAG_RESULT_SAMPLE_MASK)));

   if ((fp->Base.InputsRead & VARYING_BIT_POS) || program_uses_dfdy) {
      key.render_to_fbo = _mesa_is_user_fbo(ctx->DrawBuffer) ||
                          key.nr_color_regions > 1;
   }

   key.program_string_id = bfp->id;

   uint32_t old_prog_offset = brw->wm.base.prog_offset;
   struct brw_wm_prog_data *old_prog_data = brw->wm.prog_data;

   bool success = brw_codegen_wm_prog(brw, shader_prog, bfp, &key);

   brw->wm.base.prog_offset = old_prog_offset;
   brw->wm.prog_data = old_prog_data;

   return success;
}