xref: /external/mesa3d/src/gallium/drivers/llvmpipe/lp_state_fs.c

/**************************************************************************
 *
 * Copyright 2009 VMware, Inc.
 * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
 * All Rights Reserved.
 *
 * 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, sub license, 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 NON-INFRINGEMENT.
 * IN NO EVENT SHALL TUNGSTEN GRAPHICS 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.
 *
 **************************************************************************/

/**
 * @file
 * Code generate the whole fragment pipeline.
 *
 * The fragment pipeline consists of the following stages:
 * - early depth test
 * - fragment shader
 * - alpha test
 * - depth/stencil test
 * - blending
 *
 * This file has only the glue to assemble the fragment pipeline.  The actual
 * plumbing of converting Gallium state into LLVM IR is done elsewhere, in the
 * lp_bld_*.[ch] files, and in a complete generic and reusable way. Here we
 * muster the LLVM JIT execution engine to create a function that follows an
 * established binary interface and that can be called from C directly.
 *
 * A big source of complexity here is that we often want to run different
 * stages with different precisions and data types and precisions. For example,
 * the fragment shader needs typically to be done in floats, but the
 * depth/stencil test and blending is better done in the type that most closely
 * matches the depth/stencil and color buffer respectively.
 *
 * Since the width of a SIMD vector register stays the same regardless of the
 * element type, different types imply different number of elements, so we must
 * code generate more instances of the stages with larger types to be able to
 * feed/consume the stages with smaller types.
 *
 * @author Jose Fonseca <jfonseca@vmware.com>
 */

#include <limits.h>
#include "pipe/p_defines.h"
#include "util/u_inlines.h"
#include "util/u_memory.h"
#include "util/u_pointer.h"
#include "util/u_format.h"
#include "util/u_dump.h"
#include "util/u_string.h"
#include "util/u_simple_list.h"
#include "os/os_time.h"
#include "pipe/p_shader_tokens.h"
#include "draw/draw_context.h"
#include "tgsi/tgsi_dump.h"
#include "tgsi/tgsi_scan.h"
#include "tgsi/tgsi_parse.h"
#include "gallivm/lp_bld_type.h"
#include "gallivm/lp_bld_const.h"
#include "gallivm/lp_bld_conv.h"
#include "gallivm/lp_bld_init.h"
#include "gallivm/lp_bld_intr.h"
#include "gallivm/lp_bld_logic.h"
#include "gallivm/lp_bld_tgsi.h"
#include "gallivm/lp_bld_swizzle.h"
#include "gallivm/lp_bld_flow.h"
#include "gallivm/lp_bld_debug.h"

#include "lp_bld_alpha.h"
#include "lp_bld_blend.h"
#include "lp_bld_depth.h"
#include "lp_bld_interp.h"
#include "lp_context.h"
#include "lp_debug.h"
#include "lp_perf.h"
#include "lp_setup.h"
#include "lp_state.h"
#include "lp_tex_sample.h"
#include "lp_flush.h"
#include "lp_state_fs.h"


/** Fragment shader number (for debugging) */
static unsigned fs_no = 0;


/**
 * Expand the relevant bits of mask_input to a n*4-dword mask for the
 * n*four pixels in n 2x2 quads.  This will set the n*four elements of the
 * quad mask vector to 0 or ~0.
 * Grouping is 01, 23 for 2 quad mode hence only 0 and 2 are valid
 * quad arguments with fs length 8.
 *
 * \param first_quad  which quad(s) of the quad group to test, in [0,3]
 * \param mask_input  bitwise mask for the whole 4x4 stamp
 */
static LLVMValueRef
generate_quad_mask(struct gallivm_state *gallivm,
                   struct lp_type fs_type,
                   unsigned first_quad,
                   LLVMValueRef mask_input) /* int32 */
{
   LLVMBuilderRef builder = gallivm->builder;
   struct lp_type mask_type;
   LLVMTypeRef i32t = LLVMInt32TypeInContext(gallivm->context);
   LLVMValueRef bits[16];
   LLVMValueRef mask;
   int shift, i;

   /*
    * XXX: We'll need a different path for 16 x u8
    */
   assert(fs_type.width == 32);
   assert(fs_type.length <= Elements(bits));
   mask_type = lp_int_type(fs_type);

   /*
    * mask_input >>= (quad * 4)
    */
   switch (first_quad) {
   case 0:
      shift = 0;
      break;
   case 1:
      assert(fs_type.length == 4);
      shift = 2;
      break;
   case 2:
      shift = 8;
      break;
   case 3:
      assert(fs_type.length == 4);
      shift = 10;
      break;
   default:
      assert(0);
      shift = 0;
   }

   mask_input = LLVMBuildLShr(builder,
                              mask_input,
                              LLVMConstInt(i32t, shift, 0),
                              "");

   /*
    * mask = { mask_input & (1 << i), for i in [0,3] }
    */
   mask = lp_build_broadcast(gallivm,
                             lp_build_vec_type(gallivm, mask_type),
                             mask_input);

   for (i = 0; i < fs_type.length / 4; i++) {
      unsigned j = 2 * (i % 2) + (i / 2) * 8;
      bits[4*i + 0] = LLVMConstInt(i32t, 1 << (j + 0), 0);
      bits[4*i + 1] = LLVMConstInt(i32t, 1 << (j + 1), 0);
      bits[4*i + 2] = LLVMConstInt(i32t, 1 << (j + 4), 0);
      bits[4*i + 3] = LLVMConstInt(i32t, 1 << (j + 5), 0);
   }
   mask = LLVMBuildAnd(builder, mask, LLVMConstVector(bits, fs_type.length), "");

   /*
    * mask = mask != 0 ? ~0 : 0
    */
   mask = lp_build_compare(gallivm,
                           mask_type, PIPE_FUNC_NOTEQUAL,
                           mask,
                           lp_build_const_int_vec(gallivm, mask_type, 0));

   return mask;
}


#define EARLY_DEPTH_TEST  0x1
#define LATE_DEPTH_TEST   0x2
#define EARLY_DEPTH_WRITE 0x4
#define LATE_DEPTH_WRITE  0x8

static int
find_output_by_semantic( const struct tgsi_shader_info *info,
			 unsigned semantic,
			 unsigned index )
{
   int i;

   for (i = 0; i < info->num_outputs; i++)
      if (info->output_semantic_name[i] == semantic &&
	  info->output_semantic_index[i] == index)
	 return i;

   return -1;
}


/**
 * Generate the fragment shader, depth/stencil test, and alpha tests.
 * \param i  which quad in the tile, in range [0,3]
 * \param partial_mask  if 1, do mask_input testing
 */
static void
generate_fs(struct gallivm_state *gallivm,
            struct lp_fragment_shader *shader,
            const struct lp_fragment_shader_variant_key *key,
            LLVMBuilderRef builder,
            struct lp_type type,
            LLVMValueRef context_ptr,
            unsigned i,
            struct lp_build_interp_soa_context *interp,
            struct lp_build_sampler_soa *sampler,
            LLVMValueRef *pmask,
            LLVMValueRef (*color)[4],
            LLVMValueRef depth_ptr,
            LLVMValueRef facing,
            unsigned partial_mask,
            LLVMValueRef mask_input,
            LLVMValueRef counter)
{
   const struct util_format_description *zs_format_desc = NULL;
   const struct tgsi_token *tokens = shader->base.tokens;
   LLVMTypeRef vec_type;
   LLVMValueRef consts_ptr;
   LLVMValueRef outputs[PIPE_MAX_SHADER_OUTPUTS][TGSI_NUM_CHANNELS];
   LLVMValueRef z;
   LLVMValueRef zs_value = NULL;
   LLVMValueRef stencil_refs[2];
   struct lp_build_mask_context mask;
   boolean simple_shader = (shader->info.base.file_count[TGSI_FILE_SAMPLER] == 0 &&
                            shader->info.base.num_inputs < 3 &&
                            shader->info.base.num_instructions < 8);
   unsigned attrib;
   unsigned chan;
   unsigned cbuf;
   unsigned depth_mode;
   struct lp_bld_tgsi_system_values system_values;

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

   if (key->depth.enabled ||
       key->stencil[0].enabled ||
       key->stencil[1].enabled) {

      zs_format_desc = util_format_description(key->zsbuf_format);
      assert(zs_format_desc);

      if (!shader->info.base.writes_z) {
         if (key->alpha.enabled || shader->info.base.uses_kill)
            /* With alpha test and kill, can do the depth test early
             * and hopefully eliminate some quads.  But need to do a
             * special deferred depth write once the final mask value
             * is known.
             */
            depth_mode = EARLY_DEPTH_TEST | LATE_DEPTH_WRITE;
         else
            depth_mode = EARLY_DEPTH_TEST | EARLY_DEPTH_WRITE;
      }
      else {
         depth_mode = LATE_DEPTH_TEST | LATE_DEPTH_WRITE;
      }

      if (!(key->depth.enabled && key->depth.writemask) &&
          !(key->stencil[0].enabled && key->stencil[0].writemask))
         depth_mode &= ~(LATE_DEPTH_WRITE | EARLY_DEPTH_WRITE);
   }
   else {
      depth_mode = 0;
   }

   assert(i < 4);

   stencil_refs[0] = lp_jit_context_stencil_ref_front_value(gallivm, context_ptr);
   stencil_refs[1] = lp_jit_context_stencil_ref_back_value(gallivm, context_ptr);

   vec_type = lp_build_vec_type(gallivm, type);

   consts_ptr = lp_jit_context_constants(gallivm, context_ptr);

   memset(outputs, 0, sizeof outputs);

   /* Declare the color and z variables */
   for(cbuf = 0; cbuf < key->nr_cbufs; cbuf++) {
      for(chan = 0; chan < TGSI_NUM_CHANNELS; ++chan) {
         color[cbuf][chan] = lp_build_alloca(gallivm, vec_type, "color");
      }
   }

   /* do triangle edge testing */
   if (partial_mask) {
      *pmask = generate_quad_mask(gallivm, type,
                                  i*type.length/4, mask_input);
   }
   else {
      *pmask = lp_build_const_int_vec(gallivm, type, ~0);
   }

   /* 'mask' will control execution based on quad's pixel alive/killed state */
   lp_build_mask_begin(&mask, gallivm, type, *pmask);

   if (!(depth_mode & EARLY_DEPTH_TEST) && !simple_shader)
      lp_build_mask_check(&mask);

   lp_build_interp_soa_update_pos(interp, gallivm, i*type.length/4);
   z = interp->pos[2];

   if (depth_mode & EARLY_DEPTH_TEST) {
      lp_build_depth_stencil_test(gallivm,
                                  &key->depth,
                                  key->stencil,
                                  type,
                                  zs_format_desc,
                                  &mask,
                                  stencil_refs,
                                  z,
                                  depth_ptr, facing,
                                  &zs_value,
                                  !simple_shader);

      if (depth_mode & EARLY_DEPTH_WRITE) {
         lp_build_depth_write(builder, zs_format_desc, depth_ptr, zs_value);
      }
   }

   lp_build_interp_soa_update_inputs(interp, gallivm, i*type.length/4);

   /* Build the actual shader */
   lp_build_tgsi_soa(gallivm, tokens, type, &mask,
                     consts_ptr, &system_values,
                     interp->pos, interp->inputs,
                     outputs, sampler, &shader->info.base);

   /* Alpha test */
   if (key->alpha.enabled) {
      int color0 = find_output_by_semantic(&shader->info.base,
                                           TGSI_SEMANTIC_COLOR,
                                           0);

      if (color0 != -1 && outputs[color0][3]) {
         const struct util_format_description *cbuf_format_desc;
         LLVMValueRef alpha = LLVMBuildLoad(builder, outputs[color0][3], "alpha");
         LLVMValueRef alpha_ref_value;

         alpha_ref_value = lp_jit_context_alpha_ref_value(gallivm, context_ptr);
         alpha_ref_value = lp_build_broadcast(gallivm, vec_type, alpha_ref_value);

         cbuf_format_desc = util_format_description(key->cbuf_format[0]);

         lp_build_alpha_test(gallivm, key->alpha.func, type, cbuf_format_desc,
                             &mask, alpha, alpha_ref_value,
                             (depth_mode & LATE_DEPTH_TEST) != 0);
      }
   }

   /* Late Z test */
   if (depth_mode & LATE_DEPTH_TEST) {
      int pos0 = find_output_by_semantic(&shader->info.base,
                                         TGSI_SEMANTIC_POSITION,
                                         0);

      if (pos0 != -1 && outputs[pos0][2]) {
         z = LLVMBuildLoad(builder, outputs[pos0][2], "output.z");
      }

      lp_build_depth_stencil_test(gallivm,
                                  &key->depth,
                                  key->stencil,
                                  type,
                                  zs_format_desc,
                                  &mask,
                                  stencil_refs,
                                  z,
                                  depth_ptr, facing,
                                  &zs_value,
                                  !simple_shader);
      /* Late Z write */
      if (depth_mode & LATE_DEPTH_WRITE) {
         lp_build_depth_write(builder, zs_format_desc, depth_ptr, zs_value);
      }
   }
   else if ((depth_mode & EARLY_DEPTH_TEST) &&
            (depth_mode & LATE_DEPTH_WRITE))
   {
      /* Need to apply a reduced mask to the depth write.  Reload the
       * depth value, update from zs_value with the new mask value and
       * write that out.
       */
      lp_build_deferred_depth_write(gallivm,
                                    type,
                                    zs_format_desc,
                                    &mask,
                                    depth_ptr,
                                    zs_value);
   }


   /* Color write  */
   for (attrib = 0; attrib < shader->info.base.num_outputs; ++attrib)
   {
      if (shader->info.base.output_semantic_name[attrib] == TGSI_SEMANTIC_COLOR &&
          shader->info.base.output_semantic_index[attrib] < key->nr_cbufs)
      {
         unsigned cbuf = shader->info.base.output_semantic_index[attrib];
         for(chan = 0; chan < TGSI_NUM_CHANNELS; ++chan) {
            if(outputs[attrib][chan]) {
               /* XXX: just initialize outputs to point at colors[] and
                * skip this.
                */
               LLVMValueRef out = LLVMBuildLoad(builder, outputs[attrib][chan], "");
               lp_build_name(out, "color%u.%u.%c", i, attrib, "rgba"[chan]);
               LLVMBuildStore(builder, out, color[cbuf][chan]);
            }
         }
      }
   }

   if (counter)
      lp_build_occlusion_count(gallivm, type,
                               lp_build_mask_value(&mask), counter);

   *pmask = lp_build_mask_end(&mask);
}


/**
 * Generate the fragment shader, depth/stencil test, and alpha tests.
 */
static void
generate_fs_loop(struct gallivm_state *gallivm,
                 struct lp_fragment_shader *shader,
                 const struct lp_fragment_shader_variant_key *key,
                 LLVMBuilderRef builder,
                 struct lp_type type,
                 LLVMValueRef context_ptr,
                 LLVMValueRef num_loop,
                 struct lp_build_interp_soa_context *interp,
                 struct lp_build_sampler_soa *sampler,
                 LLVMValueRef mask_store,
                 LLVMValueRef (*out_color)[4],
                 LLVMValueRef depth_ptr,
                 unsigned depth_bits,
                 LLVMValueRef facing,
                 LLVMValueRef counter)
{
   const struct util_format_description *zs_format_desc = NULL;
   const struct tgsi_token *tokens = shader->base.tokens;
   LLVMTypeRef vec_type;
   LLVMValueRef mask_ptr, mask_val;
   LLVMValueRef consts_ptr;
   LLVMValueRef z;
   LLVMValueRef zs_value = NULL;
   LLVMValueRef stencil_refs[2];
   LLVMValueRef depth_ptr_i;
   LLVMValueRef depth_offset;
   LLVMValueRef outputs[PIPE_MAX_SHADER_OUTPUTS][TGSI_NUM_CHANNELS];
   struct lp_build_for_loop_state loop_state;
   struct lp_build_mask_context mask;
   boolean simple_shader = (shader->info.base.file_count[TGSI_FILE_SAMPLER] == 0 &&
                            shader->info.base.num_inputs < 3 &&
                            shader->info.base.num_instructions < 8);
   unsigned attrib;
   unsigned chan;
   unsigned cbuf;
   unsigned depth_mode;

   struct lp_bld_tgsi_system_values system_values;

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

   if (key->depth.enabled ||
       key->stencil[0].enabled ||
       key->stencil[1].enabled) {

      zs_format_desc = util_format_description(key->zsbuf_format);
      assert(zs_format_desc);

      if (!shader->info.base.writes_z) {
         if (key->alpha.enabled || shader->info.base.uses_kill)
            /* With alpha test and kill, can do the depth test early
             * and hopefully eliminate some quads.  But need to do a
             * special deferred depth write once the final mask value
             * is known.
             */
            depth_mode = EARLY_DEPTH_TEST | LATE_DEPTH_WRITE;
         else
            depth_mode = EARLY_DEPTH_TEST | EARLY_DEPTH_WRITE;
      }
      else {
         depth_mode = LATE_DEPTH_TEST | LATE_DEPTH_WRITE;
      }

      if (!(key->depth.enabled && key->depth.writemask) &&
          !(key->stencil[0].enabled && key->stencil[0].writemask))
         depth_mode &= ~(LATE_DEPTH_WRITE | EARLY_DEPTH_WRITE);
   }
   else {
      depth_mode = 0;
   }


   stencil_refs[0] = lp_jit_context_stencil_ref_front_value(gallivm, context_ptr);
   stencil_refs[1] = lp_jit_context_stencil_ref_back_value(gallivm, context_ptr);

   vec_type = lp_build_vec_type(gallivm, type);

   consts_ptr = lp_jit_context_constants(gallivm, context_ptr);

   lp_build_for_loop_begin(&loop_state, gallivm,
                           lp_build_const_int32(gallivm, 0),
                           LLVMIntULT,
                           num_loop,
                           lp_build_const_int32(gallivm, 1));

   mask_ptr = LLVMBuildGEP(builder, mask_store,
                           &loop_state.counter, 1, "mask_ptr");
   mask_val = LLVMBuildLoad(builder, mask_ptr, "");

   depth_offset = LLVMBuildMul(builder, loop_state.counter,
                               lp_build_const_int32(gallivm, depth_bits * type.length),
                               "");

   depth_ptr_i = LLVMBuildGEP(builder, depth_ptr, &depth_offset, 1, "");

   memset(outputs, 0, sizeof outputs);

   for(cbuf = 0; cbuf < key->nr_cbufs; cbuf++) {
      for(chan = 0; chan < TGSI_NUM_CHANNELS; ++chan) {
         out_color[cbuf][chan] = lp_build_array_alloca(gallivm,
                                                       lp_build_vec_type(gallivm,
                                                                         type),
                                                       num_loop, "color");
      }
   }



   /* 'mask' will control execution based on quad's pixel alive/killed state */
   lp_build_mask_begin(&mask, gallivm, type, mask_val);

   if (!(depth_mode & EARLY_DEPTH_TEST) && !simple_shader)
      lp_build_mask_check(&mask);

   lp_build_interp_soa_update_pos_dyn(interp, gallivm, loop_state.counter);
   z = interp->pos[2];

   if (depth_mode & EARLY_DEPTH_TEST) {
      lp_build_depth_stencil_test(gallivm,
                                  &key->depth,
                                  key->stencil,
                                  type,
                                  zs_format_desc,
                                  &mask,
                                  stencil_refs,
                                  z,
                                  depth_ptr_i, facing,
                                  &zs_value,
                                  !simple_shader);

      if (depth_mode & EARLY_DEPTH_WRITE) {
         lp_build_depth_write(builder, zs_format_desc, depth_ptr_i, zs_value);
      }
   }

   lp_build_interp_soa_update_inputs_dyn(interp, gallivm, loop_state.counter);

   /* Build the actual shader */
   lp_build_tgsi_soa(gallivm, tokens, type, &mask,
                     consts_ptr, &system_values,
                     interp->pos, interp->inputs,
                     outputs, sampler, &shader->info.base);

   /* Alpha test */
   if (key->alpha.enabled) {
      int color0 = find_output_by_semantic(&shader->info.base,
                                           TGSI_SEMANTIC_COLOR,
                                           0);

      if (color0 != -1 && outputs[color0][3]) {
         const struct util_format_description *cbuf_format_desc;
         LLVMValueRef alpha = LLVMBuildLoad(builder, outputs[color0][3], "alpha");
         LLVMValueRef alpha_ref_value;

         alpha_ref_value = lp_jit_context_alpha_ref_value(gallivm, context_ptr);
         alpha_ref_value = lp_build_broadcast(gallivm, vec_type, alpha_ref_value);

         cbuf_format_desc = util_format_description(key->cbuf_format[0]);

         lp_build_alpha_test(gallivm, key->alpha.func, type, cbuf_format_desc,
                             &mask, alpha, alpha_ref_value,
                             (depth_mode & LATE_DEPTH_TEST) != 0);
      }
   }

   /* Late Z test */
   if (depth_mode & LATE_DEPTH_TEST) {
      int pos0 = find_output_by_semantic(&shader->info.base,
                                         TGSI_SEMANTIC_POSITION,
                                         0);

      if (pos0 != -1 && outputs[pos0][2]) {
         z = LLVMBuildLoad(builder, outputs[pos0][2], "output.z");
      }

      lp_build_depth_stencil_test(gallivm,
                                  &key->depth,
                                  key->stencil,
                                  type,
                                  zs_format_desc,
                                  &mask,
                                  stencil_refs,
                                  z,
                                  depth_ptr_i, facing,
                                  &zs_value,
                                  !simple_shader);
      /* Late Z write */
      if (depth_mode & LATE_DEPTH_WRITE) {
         lp_build_depth_write(builder, zs_format_desc, depth_ptr_i, zs_value);
      }
   }
   else if ((depth_mode & EARLY_DEPTH_TEST) &&
            (depth_mode & LATE_DEPTH_WRITE))
   {
      /* Need to apply a reduced mask to the depth write.  Reload the
       * depth value, update from zs_value with the new mask value and
       * write that out.
       */
      lp_build_deferred_depth_write(gallivm,
                                    type,
                                    zs_format_desc,
                                    &mask,
                                    depth_ptr_i,
                                    zs_value);
   }


   /* Color write  */
   for (attrib = 0; attrib < shader->info.base.num_outputs; ++attrib)
   {
      if (shader->info.base.output_semantic_name[attrib] == TGSI_SEMANTIC_COLOR &&
          shader->info.base.output_semantic_index[attrib] < key->nr_cbufs)
      {
         unsigned cbuf = shader->info.base.output_semantic_index[attrib];
         for(chan = 0; chan < TGSI_NUM_CHANNELS; ++chan) {
            if(outputs[attrib][chan]) {
               /* XXX: just initialize outputs to point at colors[] and
                * skip this.
                */
               LLVMValueRef out = LLVMBuildLoad(builder, outputs[attrib][chan], "");
               LLVMValueRef color_ptr;
               color_ptr = LLVMBuildGEP(builder, out_color[cbuf][chan],
                                        &loop_state.counter, 1, "");
               lp_build_name(out, "color%u.%c", attrib, "rgba"[chan]);
               LLVMBuildStore(builder, out, color_ptr);
            }
         }
      }
   }

   if (key->occlusion_count) {
      lp_build_name(counter, "counter");
      lp_build_occlusion_count(gallivm, type,
                               lp_build_mask_value(&mask), counter);
   }

   mask_val = lp_build_mask_end(&mask);
   LLVMBuildStore(builder, mask_val, mask_ptr);
   lp_build_for_loop_end(&loop_state);
}


/**
 * Generate color blending and color output.
 * \param rt  the render target index (to index blend, colormask state)
 * \param type  the pixel color type
 * \param context_ptr  pointer to the runtime JIT context
 * \param mask  execution mask (active fragment/pixel mask)
 * \param src  colors from the fragment shader
 * \param dst_ptr  the destination color buffer pointer
 */
static void
generate_blend(struct gallivm_state *gallivm,
               const struct pipe_blend_state *blend,
               unsigned rt,
               LLVMBuilderRef builder,
               struct lp_type type,
               LLVMValueRef context_ptr,
               LLVMValueRef mask,
               LLVMValueRef *src,
               LLVMValueRef dst_ptr,
               boolean do_branch)
{
   struct lp_build_context bld;
   struct lp_build_mask_context mask_ctx;
   LLVMTypeRef vec_type;
   LLVMValueRef const_ptr;
   LLVMValueRef con[4];
   LLVMValueRef dst[4];
   LLVMValueRef res[4];
   unsigned chan;

   lp_build_context_init(&bld, gallivm, type);

   lp_build_mask_begin(&mask_ctx, gallivm, type, mask);
   if (do_branch)
      lp_build_mask_check(&mask_ctx);

   vec_type = lp_build_vec_type(gallivm, type);

   const_ptr = lp_jit_context_blend_color(gallivm, context_ptr);
   const_ptr = LLVMBuildBitCast(builder, const_ptr,
                                LLVMPointerType(vec_type, 0), "");

   /* load constant blend color and colors from the dest color buffer */
   for(chan = 0; chan < 4; ++chan) {
      LLVMValueRef index = lp_build_const_int32(gallivm, chan);
      con[chan] = LLVMBuildLoad(builder, LLVMBuildGEP(builder, const_ptr, &index, 1, ""), "");

      dst[chan] = LLVMBuildLoad(builder, LLVMBuildGEP(builder, dst_ptr, &index, 1, ""), "");

      lp_build_name(con[chan], "con.%c", "rgba"[chan]);
      lp_build_name(dst[chan], "dst.%c", "rgba"[chan]);
   }

   /* do blend */
   lp_build_blend_soa(gallivm, blend, type, rt, src, dst, con, res);

   /* store results to color buffer */
   for(chan = 0; chan < 4; ++chan) {
      if(blend->rt[rt].colormask & (1 << chan)) {
         LLVMValueRef index = lp_build_const_int32(gallivm, chan);
         lp_build_name(res[chan], "res.%c", "rgba"[chan]);
         res[chan] = lp_build_select(&bld, mask, res[chan], dst[chan]);
         LLVMBuildStore(builder, res[chan], LLVMBuildGEP(builder, dst_ptr, &index, 1, ""));
      }
   }

   lp_build_mask_end(&mask_ctx);
}


/**
 * Generate the runtime callable function for the whole fragment pipeline.
 * Note that the function which we generate operates on a block of 16
 * pixels at at time.  The block contains 2x2 quads.  Each quad contains
 * 2x2 pixels.
 */
static void
generate_fragment(struct llvmpipe_context *lp,
                  struct lp_fragment_shader *shader,
                  struct lp_fragment_shader_variant *variant,
                  unsigned partial_mask)
{
   struct gallivm_state *gallivm = variant->gallivm;
   const struct lp_fragment_shader_variant_key *key = &variant->key;
   struct lp_shader_input inputs[PIPE_MAX_SHADER_INPUTS];
   char func_name[256];
   struct lp_type fs_type;
   struct lp_type blend_type;
   LLVMTypeRef fs_elem_type;
   LLVMTypeRef blend_vec_type;
   LLVMTypeRef arg_types[11];
   LLVMTypeRef func_type;
   LLVMTypeRef int32_type = LLVMInt32TypeInContext(gallivm->context);
   LLVMTypeRef int8_type = LLVMInt8TypeInContext(gallivm->context);
   LLVMValueRef context_ptr;
   LLVMValueRef x;
   LLVMValueRef y;
   LLVMValueRef a0_ptr;
   LLVMValueRef dadx_ptr;
   LLVMValueRef dady_ptr;
   LLVMValueRef color_ptr_ptr;
   LLVMValueRef depth_ptr;
   LLVMValueRef mask_input;
   LLVMValueRef counter = NULL;
   LLVMBasicBlockRef block;
   LLVMBuilderRef builder;
   struct lp_build_sampler_soa *sampler;
   struct lp_build_interp_soa_context interp;
   LLVMValueRef fs_mask[16 / 4];
   LLVMValueRef fs_out_color[PIPE_MAX_COLOR_BUFS][TGSI_NUM_CHANNELS][16 / 4];
   LLVMValueRef blend_mask;
   LLVMValueRef function;
   LLVMValueRef facing;
   const struct util_format_description *zs_format_desc;
   unsigned num_fs;
   unsigned i;
   unsigned chan;
   unsigned cbuf;
   boolean cbuf0_write_all;
   boolean try_loop = TRUE;

   assert(lp_native_vector_width / 32 >= 4);

   /* Adjust color input interpolation according to flatshade state:
    */
   memcpy(inputs, shader->inputs, shader->info.base.num_inputs * sizeof inputs[0]);
   for (i = 0; i < shader->info.base.num_inputs; i++) {
      if (inputs[i].interp == LP_INTERP_COLOR) {
	 if (key->flatshade)
	    inputs[i].interp = LP_INTERP_CONSTANT;
	 else
	    inputs[i].interp = LP_INTERP_PERSPECTIVE;
      }
   }

   /* check if writes to cbuf[0] are to be copied to all cbufs */
   cbuf0_write_all = FALSE;
   for (i = 0;i < shader->info.base.num_properties; i++) {
      if (shader->info.base.properties[i].name ==
          TGSI_PROPERTY_FS_COLOR0_WRITES_ALL_CBUFS) {
         cbuf0_write_all = TRUE;
         break;
      }
   }

   /* TODO: actually pick these based on the fs and color buffer
    * characteristics. */

   memset(&fs_type, 0, sizeof fs_type);
   fs_type.floating = TRUE;      /* floating point values */
   fs_type.sign = TRUE;          /* values are signed */
   fs_type.norm = FALSE;         /* values are not limited to [0,1] or [-1,1] */
   fs_type.width = 32;           /* 32-bit float */
   fs_type.length = MIN2(lp_native_vector_width / 32, 16); /* n*4 elements per vector */
   num_fs = 16 / fs_type.length; /* number of loops per 4x4 stamp */

   memset(&blend_type, 0, sizeof blend_type);
   blend_type.floating = FALSE; /* values are integers */
   blend_type.sign = FALSE;     /* values are unsigned */
   blend_type.norm = TRUE;      /* values are in [0,1] or [-1,1] */
   blend_type.width = 8;        /* 8-bit ubyte values */
   blend_type.length = 16;      /* 16 elements per vector */

   /*
    * Generate the function prototype. Any change here must be reflected in
    * lp_jit.h's lp_jit_frag_func function pointer type, and vice-versa.
    */

   fs_elem_type = lp_build_elem_type(gallivm, fs_type);

   blend_vec_type = lp_build_vec_type(gallivm, blend_type);

   util_snprintf(func_name, sizeof(func_name), "fs%u_variant%u_%s",
		 shader->no, variant->no, partial_mask ? "partial" : "whole");

   arg_types[0] = variant->jit_context_ptr_type;       /* context */
   arg_types[1] = int32_type;                          /* x */
   arg_types[2] = int32_type;                          /* y */
   arg_types[3] = int32_type;                          /* facing */
   arg_types[4] = LLVMPointerType(fs_elem_type, 0);    /* a0 */
   arg_types[5] = LLVMPointerType(fs_elem_type, 0);    /* dadx */
   arg_types[6] = LLVMPointerType(fs_elem_type, 0);    /* dady */
   arg_types[7] = LLVMPointerType(LLVMPointerType(blend_vec_type, 0), 0);  /* color */
   arg_types[8] = LLVMPointerType(int8_type, 0);       /* depth */
   arg_types[9] = int32_type;                          /* mask_input */
   arg_types[10] = LLVMPointerType(int32_type, 0);     /* counter */

   func_type = LLVMFunctionType(LLVMVoidTypeInContext(gallivm->context),
                                arg_types, Elements(arg_types), 0);

   function = LLVMAddFunction(gallivm->module, func_name, func_type);
   LLVMSetFunctionCallConv(function, LLVMCCallConv);

   variant->function[partial_mask] = function;

   /* XXX: need to propagate noalias down into color param now we are
    * passing a pointer-to-pointer?
    */
   for(i = 0; i < Elements(arg_types); ++i)
      if(LLVMGetTypeKind(arg_types[i]) == LLVMPointerTypeKind)
         LLVMAddAttribute(LLVMGetParam(function, i), LLVMNoAliasAttribute);

   context_ptr  = LLVMGetParam(function, 0);
   x            = LLVMGetParam(function, 1);
   y            = LLVMGetParam(function, 2);
   facing       = LLVMGetParam(function, 3);
   a0_ptr       = LLVMGetParam(function, 4);
   dadx_ptr     = LLVMGetParam(function, 5);
   dady_ptr     = LLVMGetParam(function, 6);
   color_ptr_ptr = LLVMGetParam(function, 7);
   depth_ptr    = LLVMGetParam(function, 8);
   mask_input   = LLVMGetParam(function, 9);

   lp_build_name(context_ptr, "context");
   lp_build_name(x, "x");
   lp_build_name(y, "y");
   lp_build_name(a0_ptr, "a0");
   lp_build_name(dadx_ptr, "dadx");
   lp_build_name(dady_ptr, "dady");
   lp_build_name(color_ptr_ptr, "color_ptr_ptr");
   lp_build_name(depth_ptr, "depth");
   lp_build_name(mask_input, "mask_input");

   if (key->occlusion_count) {
      counter = LLVMGetParam(function, 10);
      lp_build_name(counter, "counter");
   }

   /*
    * Function body
    */

   block = LLVMAppendBasicBlockInContext(gallivm->context, function, "entry");
   builder = gallivm->builder;
   assert(builder);
   LLVMPositionBuilderAtEnd(builder, block);

   /* code generated texture sampling */
   sampler = lp_llvm_sampler_soa_create(key->sampler, context_ptr);

   zs_format_desc = util_format_description(key->zsbuf_format);

   if (!try_loop) {
      /*
       * The shader input interpolation info is not explicitely baked in the
       * shader key, but everything it derives from (TGSI, and flatshade) is
       * already included in the shader key.
       */
      lp_build_interp_soa_init(&interp,
                               gallivm,
                               shader->info.base.num_inputs,
                               inputs,
                               builder, fs_type,
                               FALSE,
                               a0_ptr, dadx_ptr, dady_ptr,
                               x, y);

      /* loop over quads in the block */
      for(i = 0; i < num_fs; ++i) {
         LLVMValueRef depth_offset = LLVMConstInt(int32_type,
                                                  i*fs_type.length*zs_format_desc->block.bits/8,
                                                  0);
         LLVMValueRef out_color[PIPE_MAX_COLOR_BUFS][TGSI_NUM_CHANNELS];
         LLVMValueRef depth_ptr_i;

         depth_ptr_i = LLVMBuildGEP(builder, depth_ptr, &depth_offset, 1, "");

         generate_fs(gallivm,
                     shader, key,
                     builder,
                     fs_type,
                     context_ptr,
                     i,
                     &interp,
                     sampler,
                     &fs_mask[i], /* output */
                     out_color,
                     depth_ptr_i,
                     facing,
                     partial_mask,
                     mask_input,
                     counter);

         for (cbuf = 0; cbuf < key->nr_cbufs; cbuf++)
            for (chan = 0; chan < TGSI_NUM_CHANNELS; ++chan)
               fs_out_color[cbuf][chan][i] =
                  out_color[cbuf * !cbuf0_write_all][chan];
      }
   }
   else {
      unsigned depth_bits = zs_format_desc->block.bits/8;
      LLVMValueRef num_loop = lp_build_const_int32(gallivm, num_fs);
      LLVMTypeRef mask_type = lp_build_int_vec_type(gallivm, fs_type);
      LLVMValueRef mask_store = lp_build_array_alloca(gallivm, mask_type,
                                                      num_loop, "mask_store");
      LLVMValueRef color_store[PIPE_MAX_COLOR_BUFS][TGSI_NUM_CHANNELS];

      /*
       * The shader input interpolation info is not explicitely baked in the
       * shader key, but everything it derives from (TGSI, and flatshade) is
       * already included in the shader key.
       */
      lp_build_interp_soa_init(&interp,
                               gallivm,
                               shader->info.base.num_inputs,
                               inputs,
                               builder, fs_type,
                               TRUE,
                               a0_ptr, dadx_ptr, dady_ptr,
                               x, y);

      for (i = 0; i < num_fs; i++) {
         LLVMValueRef mask;
         LLVMValueRef indexi = lp_build_const_int32(gallivm, i);
         LLVMValueRef mask_ptr = LLVMBuildGEP(builder, mask_store,
                                              &indexi, 1, "mask_ptr");

         if (partial_mask) {
            mask = generate_quad_mask(gallivm, fs_type,
                                      i*fs_type.length/4, mask_input);
         }
         else {
            mask = lp_build_const_int_vec(gallivm, fs_type, ~0);
         }
         LLVMBuildStore(builder, mask, mask_ptr);
      }

      generate_fs_loop(gallivm,
                       shader, key,
                       builder,
                       fs_type,
                       context_ptr,
                       num_loop,
                       &interp,
                       sampler,
                       mask_store, /* output */
                       color_store,
                       depth_ptr,
                       depth_bits,
                       facing,
                       counter);

      for (i = 0; i < num_fs; i++) {
         LLVMValueRef indexi = lp_build_const_int32(gallivm, i);
         LLVMValueRef ptr = LLVMBuildGEP(builder, mask_store,
                                         &indexi, 1, "");
         fs_mask[i] = LLVMBuildLoad(builder, ptr, "mask");
         /* This is fucked up need to reorganize things */
         for (cbuf = 0; cbuf < key->nr_cbufs; cbuf++) {
            for (chan = 0; chan < TGSI_NUM_CHANNELS; ++chan) {
               ptr = LLVMBuildGEP(builder,
                                  color_store[cbuf * !cbuf0_write_all][chan],
                                  &indexi, 1, "");
               fs_out_color[cbuf][chan][i] = ptr;
            }
         }
      }
   }

   sampler->destroy(sampler);

   /* Loop over color outputs / color buffers to do blending.
    */
   for(cbuf = 0; cbuf < key->nr_cbufs; cbuf++) {
      LLVMValueRef color_ptr;
      LLVMValueRef index = lp_build_const_int32(gallivm, cbuf);
      LLVMValueRef blend_in_color[TGSI_NUM_CHANNELS];
      unsigned rt;

      /*
       * Convert the fs's output color and mask to fit to the blending type.
       */
      for(chan = 0; chan < TGSI_NUM_CHANNELS; ++chan) {
         LLVMValueRef fs_color_vals[LP_MAX_VECTOR_LENGTH];

         for (i = 0; i < num_fs; i++) {
            fs_color_vals[i] =
               LLVMBuildLoad(builder, fs_out_color[cbuf][chan][i], "fs_color_vals");
         }

         lp_build_conv(gallivm, fs_type, blend_type,
                       fs_color_vals,
                       num_fs,
                       &blend_in_color[chan], 1);

         lp_build_name(blend_in_color[chan], "color%d.%c", cbuf, "rgba"[chan]);
      }

      if (partial_mask || !variant->opaque) {
         lp_build_conv_mask(variant->gallivm, fs_type, blend_type,
                            fs_mask, num_fs,
                            &blend_mask, 1);
      } else {
         blend_mask = lp_build_const_int_vec(variant->gallivm, blend_type, ~0);
      }

      color_ptr = LLVMBuildLoad(builder,
                                LLVMBuildGEP(builder, color_ptr_ptr, &index, 1, ""),
                                "");
      lp_build_name(color_ptr, "color_ptr%d", cbuf);

      /* which blend/colormask state to use */
      rt = key->blend.independent_blend_enable ? cbuf : 0;

      /*
       * Blending.
       */
      {
         /* Could the 4x4 have been killed?
          */
         boolean do_branch = ((key->depth.enabled || key->stencil[0].enabled) &&
                              !key->alpha.enabled &&
                              !shader->info.base.uses_kill);

         generate_blend(variant->gallivm,
                        &key->blend,
                        rt,
                        builder,
                        blend_type,
                        context_ptr,
                        blend_mask,
                        blend_in_color,
                        color_ptr,
                        do_branch);
      }
   }

   LLVMBuildRetVoid(builder);

   gallivm_verify_function(gallivm, function);

   variant->nr_instrs += lp_build_count_instructions(function);
}


static void
dump_fs_variant_key(const struct lp_fragment_shader_variant_key *key)
{
   unsigned i;

   debug_printf("fs variant %p:\n", (void *) key);

   if (key->flatshade) {
      debug_printf("flatshade = 1\n");
   }
   for (i = 0; i < key->nr_cbufs; ++i) {
      debug_printf("cbuf_format[%u] = %s\n", i, util_format_name(key->cbuf_format[i]));
   }
   if (key->depth.enabled) {
      debug_printf("depth.format = %s\n", util_format_name(key->zsbuf_format));
      debug_printf("depth.func = %s\n", util_dump_func(key->depth.func, TRUE));
      debug_printf("depth.writemask = %u\n", key->depth.writemask);
   }

   for (i = 0; i < 2; ++i) {
      if (key->stencil[i].enabled) {
         debug_printf("stencil[%u].func = %s\n", i, util_dump_func(key->stencil[i].func, TRUE));
         debug_printf("stencil[%u].fail_op = %s\n", i, util_dump_stencil_op(key->stencil[i].fail_op, TRUE));
         debug_printf("stencil[%u].zpass_op = %s\n", i, util_dump_stencil_op(key->stencil[i].zpass_op, TRUE));
         debug_printf("stencil[%u].zfail_op = %s\n", i, util_dump_stencil_op(key->stencil[i].zfail_op, TRUE));
         debug_printf("stencil[%u].valuemask = 0x%x\n", i, key->stencil[i].valuemask);
         debug_printf("stencil[%u].writemask = 0x%x\n", i, key->stencil[i].writemask);
      }
   }

   if (key->alpha.enabled) {
      debug_printf("alpha.func = %s\n", util_dump_func(key->alpha.func, TRUE));
   }

   if (key->occlusion_count) {
      debug_printf("occlusion_count = 1\n");
   }

   if (key->blend.logicop_enable) {
      debug_printf("blend.logicop_func = %s\n", util_dump_logicop(key->blend.logicop_func, TRUE));
   }
   else if (key->blend.rt[0].blend_enable) {
      debug_printf("blend.rgb_func = %s\n",   util_dump_blend_func  (key->blend.rt[0].rgb_func, TRUE));
      debug_printf("blend.rgb_src_factor = %s\n",   util_dump_blend_factor(key->blend.rt[0].rgb_src_factor, TRUE));
      debug_printf("blend.rgb_dst_factor = %s\n",   util_dump_blend_factor(key->blend.rt[0].rgb_dst_factor, TRUE));
      debug_printf("blend.alpha_func = %s\n",       util_dump_blend_func  (key->blend.rt[0].alpha_func, TRUE));
      debug_printf("blend.alpha_src_factor = %s\n", util_dump_blend_factor(key->blend.rt[0].alpha_src_factor, TRUE));
      debug_printf("blend.alpha_dst_factor = %s\n", util_dump_blend_factor(key->blend.rt[0].alpha_dst_factor, TRUE));
   }
   debug_printf("blend.colormask = 0x%x\n", key->blend.rt[0].colormask);
   for (i = 0; i < key->nr_samplers; ++i) {
      debug_printf("sampler[%u] = \n", i);
      debug_printf("  .format = %s\n",
                   util_format_name(key->sampler[i].format));
      debug_printf("  .target = %s\n",
                   util_dump_tex_target(key->sampler[i].target, TRUE));
      debug_printf("  .pot = %u %u %u\n",
                   key->sampler[i].pot_width,
                   key->sampler[i].pot_height,
                   key->sampler[i].pot_depth);
      debug_printf("  .wrap = %s %s %s\n",
                   util_dump_tex_wrap(key->sampler[i].wrap_s, TRUE),
                   util_dump_tex_wrap(key->sampler[i].wrap_t, TRUE),
                   util_dump_tex_wrap(key->sampler[i].wrap_r, TRUE));
      debug_printf("  .min_img_filter = %s\n",
                   util_dump_tex_filter(key->sampler[i].min_img_filter, TRUE));
      debug_printf("  .min_mip_filter = %s\n",
                   util_dump_tex_mipfilter(key->sampler[i].min_mip_filter, TRUE));
      debug_printf("  .mag_img_filter = %s\n",
                   util_dump_tex_filter(key->sampler[i].mag_img_filter, TRUE));
      if (key->sampler[i].compare_mode != PIPE_TEX_COMPARE_NONE)
         debug_printf("  .compare_func = %s\n", util_dump_func(key->sampler[i].compare_func, TRUE));
      debug_printf("  .normalized_coords = %u\n", key->sampler[i].normalized_coords);
      debug_printf("  .min_max_lod_equal = %u\n", key->sampler[i].min_max_lod_equal);
      debug_printf("  .lod_bias_non_zero = %u\n", key->sampler[i].lod_bias_non_zero);
      debug_printf("  .apply_min_lod = %u\n", key->sampler[i].apply_min_lod);
      debug_printf("  .apply_max_lod = %u\n", key->sampler[i].apply_max_lod);
   }
}


void
lp_debug_fs_variant(const struct lp_fragment_shader_variant *variant)
{
   debug_printf("llvmpipe: Fragment shader #%u variant #%u:\n",
                variant->shader->no, variant->no);
   tgsi_dump(variant->shader->base.tokens, 0);
   dump_fs_variant_key(&variant->key);
   debug_printf("variant->opaque = %u\n", variant->opaque);
   debug_printf("\n");
}


/**
 * Generate a new fragment shader variant from the shader code and
 * other state indicated by the key.
 */
static struct lp_fragment_shader_variant *
generate_variant(struct llvmpipe_context *lp,
                 struct lp_fragment_shader *shader,
                 const struct lp_fragment_shader_variant_key *key)
{
   struct lp_fragment_shader_variant *variant;
   const struct util_format_description *cbuf0_format_desc;
   boolean fullcolormask;

   variant = CALLOC_STRUCT(lp_fragment_shader_variant);
   if(!variant)
      return NULL;

   variant->gallivm = gallivm_create();
   if (!variant->gallivm) {
      FREE(variant);
      return NULL;
   }

   variant->shader = shader;
   variant->list_item_global.base = variant;
   variant->list_item_local.base = variant;
   variant->no = shader->variants_created++;

   memcpy(&variant->key, key, shader->variant_key_size);

   /*
    * Determine whether we are touching all channels in the color buffer.
    */
   fullcolormask = FALSE;
   if (key->nr_cbufs == 1) {
      cbuf0_format_desc = util_format_description(key->cbuf_format[0]);
      fullcolormask = util_format_colormask_full(cbuf0_format_desc, key->blend.rt[0].colormask);
   }

   variant->opaque =
         !key->blend.logicop_enable &&
         !key->blend.rt[0].blend_enable &&
         fullcolormask &&
         !key->stencil[0].enabled &&
         !key->alpha.enabled &&
         !key->depth.enabled &&
         !shader->info.base.uses_kill
         ? TRUE : FALSE;


   if ((LP_DEBUG & DEBUG_FS) || (gallivm_debug & GALLIVM_DEBUG_IR)) {
      lp_debug_fs_variant(variant);
   }

   lp_jit_init_types(variant);

   if (variant->jit_function[RAST_EDGE_TEST] == NULL)
      generate_fragment(lp, shader, variant, RAST_EDGE_TEST);

   if (variant->jit_function[RAST_WHOLE] == NULL) {
      if (variant->opaque) {
         /* Specialized shader, which doesn't need to read the color buffer. */
         generate_fragment(lp, shader, variant, RAST_WHOLE);
      }
   }

   /*
    * Compile everything
    */

   gallivm_compile_module(variant->gallivm);

   if (variant->function[RAST_EDGE_TEST]) {
      variant->jit_function[RAST_EDGE_TEST] = (lp_jit_frag_func)
            gallivm_jit_function(variant->gallivm,
                                 variant->function[RAST_EDGE_TEST]);
   }

   if (variant->function[RAST_WHOLE]) {
         variant->jit_function[RAST_WHOLE] = (lp_jit_frag_func)
               gallivm_jit_function(variant->gallivm,
                                    variant->function[RAST_WHOLE]);
   } else if (!variant->jit_function[RAST_WHOLE]) {
      variant->jit_function[RAST_WHOLE] = variant->jit_function[RAST_EDGE_TEST];
   }

   return variant;
}


static void *
llvmpipe_create_fs_state(struct pipe_context *pipe,
                         const struct pipe_shader_state *templ)
{
   struct llvmpipe_context *llvmpipe = llvmpipe_context(pipe);
   struct lp_fragment_shader *shader;
   int nr_samplers;
   int i;

   shader = CALLOC_STRUCT(lp_fragment_shader);
   if (!shader)
      return NULL;

   shader->no = fs_no++;
   make_empty_list(&shader->variants);

   /* get/save the summary info for this shader */
   lp_build_tgsi_info(templ->tokens, &shader->info);

   /* we need to keep a local copy of the tokens */
   shader->base.tokens = tgsi_dup_tokens(templ->tokens);

   shader->draw_data = draw_create_fragment_shader(llvmpipe->draw, templ);
   if (shader->draw_data == NULL) {
      FREE((void *) shader->base.tokens);
      FREE(shader);
      return NULL;
   }

   nr_samplers = shader->info.base.file_max[TGSI_FILE_SAMPLER] + 1;

   shader->variant_key_size = Offset(struct lp_fragment_shader_variant_key,
				     sampler[nr_samplers]);

   for (i = 0; i < shader->info.base.num_inputs; i++) {
      shader->inputs[i].usage_mask = shader->info.base.input_usage_mask[i];
      shader->inputs[i].cyl_wrap = shader->info.base.input_cylindrical_wrap[i];

      switch (shader->info.base.input_interpolate[i]) {
      case TGSI_INTERPOLATE_CONSTANT:
	 shader->inputs[i].interp = LP_INTERP_CONSTANT;
	 break;
      case TGSI_INTERPOLATE_LINEAR:
	 shader->inputs[i].interp = LP_INTERP_LINEAR;
	 break;
      case TGSI_INTERPOLATE_PERSPECTIVE:
	 shader->inputs[i].interp = LP_INTERP_PERSPECTIVE;
	 break;
      case TGSI_INTERPOLATE_COLOR:
	 shader->inputs[i].interp = LP_INTERP_COLOR;
	 break;
      default:
	 assert(0);
	 break;
      }

      switch (shader->info.base.input_semantic_name[i]) {
      case TGSI_SEMANTIC_FACE:
	 shader->inputs[i].interp = LP_INTERP_FACING;
	 break;
      case TGSI_SEMANTIC_POSITION:
	 /* Position was already emitted above
	  */
	 shader->inputs[i].interp = LP_INTERP_POSITION;
	 shader->inputs[i].src_index = 0;
	 continue;
      }

      shader->inputs[i].src_index = i+1;
   }

   if (LP_DEBUG & DEBUG_TGSI) {
      unsigned attrib;
      debug_printf("llvmpipe: Create fragment shader #%u %p:\n",
                   shader->no, (void *) shader);
      tgsi_dump(templ->tokens, 0);
      debug_printf("usage masks:\n");
      for (attrib = 0; attrib < shader->info.base.num_inputs; ++attrib) {
         unsigned usage_mask = shader->info.base.input_usage_mask[attrib];
         debug_printf("  IN[%u].%s%s%s%s\n",
                      attrib,
                      usage_mask & TGSI_WRITEMASK_X ? "x" : "",
                      usage_mask & TGSI_WRITEMASK_Y ? "y" : "",
                      usage_mask & TGSI_WRITEMASK_Z ? "z" : "",
                      usage_mask & TGSI_WRITEMASK_W ? "w" : "");
      }
      debug_printf("\n");
   }

   return shader;
}


static void
llvmpipe_bind_fs_state(struct pipe_context *pipe, void *fs)
{
   struct llvmpipe_context *llvmpipe = llvmpipe_context(pipe);

   if (llvmpipe->fs == fs)
      return;

   draw_flush(llvmpipe->draw);

   llvmpipe->fs = (struct lp_fragment_shader *) fs;

   draw_bind_fragment_shader(llvmpipe->draw,
                             (llvmpipe->fs ? llvmpipe->fs->draw_data : NULL));

   llvmpipe->dirty |= LP_NEW_FS;
}


/**
 * Remove shader variant from two lists: the shader's variant list
 * and the context's variant list.
 */
void
llvmpipe_remove_shader_variant(struct llvmpipe_context *lp,
                               struct lp_fragment_shader_variant *variant)
{
   unsigned i;

   if (gallivm_debug & GALLIVM_DEBUG_IR) {
      debug_printf("llvmpipe: del fs #%u var #%u v created #%u v cached"
                   " #%u v total cached #%u\n",
                   variant->shader->no,
                   variant->no,
                   variant->shader->variants_created,
                   variant->shader->variants_cached,
                   lp->nr_fs_variants);
   }

   /* free all the variant's JIT'd functions */
   for (i = 0; i < Elements(variant->function); i++) {
      if (variant->function[i]) {
         gallivm_free_function(variant->gallivm,
                               variant->function[i],
                               variant->jit_function[i]);
      }
   }

   gallivm_destroy(variant->gallivm);

   /* remove from shader's list */
   remove_from_list(&variant->list_item_local);
   variant->shader->variants_cached--;

   /* remove from context's list */
   remove_from_list(&variant->list_item_global);
   lp->nr_fs_variants--;
   lp->nr_fs_instrs -= variant->nr_instrs;

   FREE(variant);
}


static void
llvmpipe_delete_fs_state(struct pipe_context *pipe, void *fs)
{
   struct llvmpipe_context *llvmpipe = llvmpipe_context(pipe);
   struct lp_fragment_shader *shader = fs;
   struct lp_fs_variant_list_item *li;

   assert(fs != llvmpipe->fs);

   /*
    * XXX: we need to flush the context until we have some sort of reference
    * counting in fragment shaders as they may still be binned
    * Flushing alone might not sufficient we need to wait on it too.
    */
   llvmpipe_finish(pipe, __FUNCTION__);

   /* Delete all the variants */
   li = first_elem(&shader->variants);
   while(!at_end(&shader->variants, li)) {
      struct lp_fs_variant_list_item *next = next_elem(li);
      llvmpipe_remove_shader_variant(llvmpipe, li->base);
      li = next;
   }

   /* Delete draw module's data */
   draw_delete_fragment_shader(llvmpipe->draw, shader->draw_data);

   assert(shader->variants_cached == 0);
   FREE((void *) shader->base.tokens);
   FREE(shader);
}



static void
llvmpipe_set_constant_buffer(struct pipe_context *pipe,
                             uint shader, uint index,
                             struct pipe_constant_buffer *cb)
{
   struct llvmpipe_context *llvmpipe = llvmpipe_context(pipe);
   struct pipe_resource *constants = cb ? cb->buffer : NULL;
   unsigned size;
   const void *data;

   if (cb && cb->user_buffer) {
      constants = llvmpipe_user_buffer_create(pipe->screen,
                                              (void *) cb->user_buffer,
                                              cb->buffer_size,
                                              PIPE_BIND_CONSTANT_BUFFER);
   }

   size = constants ? constants->width0 : 0;
   data = constants ? llvmpipe_resource_data(constants) : NULL;

   assert(shader < PIPE_SHADER_TYPES);
   assert(index < PIPE_MAX_CONSTANT_BUFFERS);

   if(llvmpipe->constants[shader][index] == constants)
      return;

   draw_flush(llvmpipe->draw);

   /* note: reference counting */
   pipe_resource_reference(&llvmpipe->constants[shader][index], constants);

   if(shader == PIPE_SHADER_VERTEX ||
      shader == PIPE_SHADER_GEOMETRY) {
      draw_set_mapped_constant_buffer(llvmpipe->draw, shader,
                                      index, data, size);
   }

   llvmpipe->dirty |= LP_NEW_CONSTANTS;

   if (cb && cb->user_buffer) {
      pipe_resource_reference(&constants, NULL);
   }
}


/**
 * Return the blend factor equivalent to a destination alpha of one.
 */
static INLINE unsigned
force_dst_alpha_one(unsigned factor)
{
   switch(factor) {
   case PIPE_BLENDFACTOR_DST_ALPHA:
      return PIPE_BLENDFACTOR_ONE;
   case PIPE_BLENDFACTOR_INV_DST_ALPHA:
      return PIPE_BLENDFACTOR_ZERO;
   case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE:
      return PIPE_BLENDFACTOR_ZERO;
   }

   return factor;
}


/**
 * We need to generate several variants of the fragment pipeline to match
 * all the combinations of the contributing state atoms.
 *
 * TODO: there is actually no reason to tie this to context state -- the
 * generated code could be cached globally in the screen.
 */
static void
make_variant_key(struct llvmpipe_context *lp,
                 struct lp_fragment_shader *shader,
                 struct lp_fragment_shader_variant_key *key)
{
   unsigned i;

   memset(key, 0, shader->variant_key_size);

   if (lp->framebuffer.zsbuf) {
      if (lp->depth_stencil->depth.enabled) {
         key->zsbuf_format = lp->framebuffer.zsbuf->format;
         memcpy(&key->depth, &lp->depth_stencil->depth, sizeof key->depth);
      }
      if (lp->depth_stencil->stencil[0].enabled) {
         key->zsbuf_format = lp->framebuffer.zsbuf->format;
         memcpy(&key->stencil, &lp->depth_stencil->stencil, sizeof key->stencil);
      }
   }

   key->alpha.enabled = lp->depth_stencil->alpha.enabled;
   if(key->alpha.enabled)
      key->alpha.func = lp->depth_stencil->alpha.func;
   /* alpha.ref_value is passed in jit_context */

   key->flatshade = lp->rasterizer->flatshade;
   if (lp->active_query_count) {
      key->occlusion_count = TRUE;
   }

   if (lp->framebuffer.nr_cbufs) {
      memcpy(&key->blend, lp->blend, sizeof key->blend);
   }

   key->nr_cbufs = lp->framebuffer.nr_cbufs;
   for (i = 0; i < lp->framebuffer.nr_cbufs; i++) {
      enum pipe_format format = lp->framebuffer.cbufs[i]->format;
      struct pipe_rt_blend_state *blend_rt = &key->blend.rt[i];
      const struct util_format_description *format_desc;

      key->cbuf_format[i] = format;

      format_desc = util_format_description(format);
      assert(format_desc->colorspace == UTIL_FORMAT_COLORSPACE_RGB ||
             format_desc->colorspace == UTIL_FORMAT_COLORSPACE_SRGB);

      blend_rt->colormask = lp->blend->rt[i].colormask;

      /*
       * Mask out color channels not present in the color buffer.
       */
      blend_rt->colormask &= util_format_colormask(format_desc);

      /*
       * Our swizzled render tiles always have an alpha channel, but the linear
       * render target format often does not, so force here the dst alpha to be
       * one.
       *
       * This is not a mere optimization. Wrong results will be produced if the
       * dst alpha is used, the dst format does not have alpha, and the previous
       * rendering was not flushed from the swizzled to linear buffer. For
       * example, NonPowTwo DCT.
       *
       * TODO: This should be generalized to all channels for better
       * performance, but only alpha causes correctness issues.
       *
       * Also, force rgb/alpha func/factors match, to make AoS blending easier.
       */
      if (format_desc->swizzle[3] > UTIL_FORMAT_SWIZZLE_W ||
	  format_desc->swizzle[3] == format_desc->swizzle[0]) {
         blend_rt->rgb_src_factor   = force_dst_alpha_one(blend_rt->rgb_src_factor);
         blend_rt->rgb_dst_factor   = force_dst_alpha_one(blend_rt->rgb_dst_factor);
         blend_rt->alpha_func       = blend_rt->rgb_func;
         blend_rt->alpha_src_factor = blend_rt->rgb_src_factor;
         blend_rt->alpha_dst_factor = blend_rt->rgb_dst_factor;
      }
   }

   /* This value will be the same for all the variants of a given shader:
    */
   key->nr_samplers = shader->info.base.file_max[TGSI_FILE_SAMPLER] + 1;

   for(i = 0; i < key->nr_samplers; ++i) {
      if(shader->info.base.file_mask[TGSI_FILE_SAMPLER] & (1 << i)) {
         lp_sampler_static_state(&key->sampler[i],
				 lp->fragment_sampler_views[i],
				 lp->sampler[i]);
      }
   }
}



/**
 * Update fragment shader state.  This is called just prior to drawing
 * something when some fragment-related state has changed.
 */
void
llvmpipe_update_fs(struct llvmpipe_context *lp)
{
   struct lp_fragment_shader *shader = lp->fs;
   struct lp_fragment_shader_variant_key key;
   struct lp_fragment_shader_variant *variant = NULL;
   struct lp_fs_variant_list_item *li;

   make_variant_key(lp, shader, &key);

   /* Search the variants for one which matches the key */
   li = first_elem(&shader->variants);
   while(!at_end(&shader->variants, li)) {
      if(memcmp(&li->base->key, &key, shader->variant_key_size) == 0) {
         variant = li->base;
         break;
      }
      li = next_elem(li);
   }

   if (variant) {
      /* Move this variant to the head of the list to implement LRU
       * deletion of shader's when we have too many.
       */
      move_to_head(&lp->fs_variants_list, &variant->list_item_global);
   }
   else {
      /* variant not found, create it now */
      int64_t t0, t1, dt;
      unsigned i;
      unsigned variants_to_cull;

      if (0) {
         debug_printf("%u variants,\t%u instrs,\t%u instrs/variant\n",
                      lp->nr_fs_variants,
                      lp->nr_fs_instrs,
                      lp->nr_fs_variants ? lp->nr_fs_instrs / lp->nr_fs_variants : 0);
      }

      /* First, check if we've exceeded the max number of shader variants.
       * If so, free 25% of them (the least recently used ones).
       */
      variants_to_cull = lp->nr_fs_variants >= LP_MAX_SHADER_VARIANTS ? LP_MAX_SHADER_VARIANTS / 4 : 0;

      if (variants_to_cull ||
          lp->nr_fs_instrs >= LP_MAX_SHADER_INSTRUCTIONS) {
         struct pipe_context *pipe = &lp->pipe;

         /*
          * XXX: we need to flush the context until we have some sort of
          * reference counting in fragment shaders as they may still be binned
          * Flushing alone might not be sufficient we need to wait on it too.
          */
         llvmpipe_finish(pipe, __FUNCTION__);

         /*
          * We need to re-check lp->nr_fs_variants because an arbitrarliy large
          * number of shader variants (potentially all of them) could be
          * pending for destruction on flush.
          */

         for (i = 0; i < variants_to_cull || lp->nr_fs_instrs >= LP_MAX_SHADER_INSTRUCTIONS; i++) {
            struct lp_fs_variant_list_item *item;
            if (is_empty_list(&lp->fs_variants_list)) {
               break;
            }
            item = last_elem(&lp->fs_variants_list);
            assert(item);
            assert(item->base);
            llvmpipe_remove_shader_variant(lp, item->base);
         }
      }

      /*
       * Generate the new variant.
       */
      t0 = os_time_get();
      variant = generate_variant(lp, shader, &key);
      t1 = os_time_get();
      dt = t1 - t0;
      LP_COUNT_ADD(llvm_compile_time, dt);
      LP_COUNT_ADD(nr_llvm_compiles, 2);  /* emit vs. omit in/out test */

      llvmpipe_variant_count++;

      /* Put the new variant into the list */
      if (variant) {
         insert_at_head(&shader->variants, &variant->list_item_local);
         insert_at_head(&lp->fs_variants_list, &variant->list_item_global);
         lp->nr_fs_variants++;
         lp->nr_fs_instrs += variant->nr_instrs;
         shader->variants_cached++;
      }
   }

   /* Bind this variant */
   lp_setup_set_fs_variant(lp->setup, variant);
}







void
llvmpipe_init_fs_funcs(struct llvmpipe_context *llvmpipe)
{
   llvmpipe->pipe.create_fs_state = llvmpipe_create_fs_state;
   llvmpipe->pipe.bind_fs_state   = llvmpipe_bind_fs_state;
   llvmpipe->pipe.delete_fs_state = llvmpipe_delete_fs_state;

   llvmpipe->pipe.set_constant_buffer = llvmpipe_set_constant_buffer;
}