xref: /third_party/mesa3d/src/gallium/drivers/i915/i915_fpc_optimize.c

/**************************************************************************
 *
 * Copyright 2011 The Chromium OS authors.
 * 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 GOOGLE 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 "i915_context.h"
#include "i915_fpc.h"
#include "i915_reg.h"

#include "pipe/p_shader_tokens.h"
#include "tgsi/tgsi_dump.h"
#include "tgsi/tgsi_exec.h"
#include "tgsi/tgsi_parse.h"
#include "util/u_math.h"
#include "util/u_memory.h"
#include "util/u_string.h"

struct i915_optimize_context {
   int first_write[TGSI_EXEC_NUM_TEMPS];
   int last_read[TGSI_EXEC_NUM_TEMPS];
};

static bool
same_src_dst_reg(struct i915_full_src_register *s1,
                 struct i915_full_dst_register *d1)
{
   return (s1->Register.File == d1->Register.File &&
           s1->Register.Indirect == d1->Register.Indirect &&
           s1->Register.Dimension == d1->Register.Dimension &&
           s1->Register.Index == d1->Register.Index);
}

static bool
same_dst_reg(struct i915_full_dst_register *d1,
             struct i915_full_dst_register *d2)
{
   return (d1->Register.File == d2->Register.File &&
           d1->Register.Indirect == d2->Register.Indirect &&
           d1->Register.Dimension == d2->Register.Dimension &&
           d1->Register.Index == d2->Register.Index);
}

static bool
same_src_reg(struct i915_full_src_register *d1,
             struct i915_full_src_register *d2)
{
   return (d1->Register.File == d2->Register.File &&
           d1->Register.Indirect == d2->Register.Indirect &&
           d1->Register.Dimension == d2->Register.Dimension &&
           d1->Register.Index == d2->Register.Index &&
           d1->Register.Absolute == d2->Register.Absolute &&
           d1->Register.Negate == d2->Register.Negate);
}

static const struct {
   bool is_texture;
   bool commutes;
   unsigned neutral_element;
   unsigned num_dst;
   unsigned num_src;
} op_table[TGSI_OPCODE_LAST] = {
   [TGSI_OPCODE_ADD] = {false, true, TGSI_SWIZZLE_ZERO, 1, 2},
   [TGSI_OPCODE_CEIL] = {false, false, 0, 1, 1},
   [TGSI_OPCODE_CMP] = {false, false, 0, 1, 2},
   [TGSI_OPCODE_COS] = {false, false, 0, 1, 1},
   [TGSI_OPCODE_DDX] = {false, false, 0, 1, 0},
   [TGSI_OPCODE_DDY] = {false, false, 0, 1, 0},
   [TGSI_OPCODE_DP2] = {false, true, TGSI_SWIZZLE_ONE, 1, 2},
   [TGSI_OPCODE_DP3] = {false, true, TGSI_SWIZZLE_ONE, 1, 2},
   [TGSI_OPCODE_DP4] = {false, true, TGSI_SWIZZLE_ONE, 1, 2},
   [TGSI_OPCODE_DST] = {false, false, 0, 1, 2},
   [TGSI_OPCODE_END] = {false, false, 0, 0, 0},
   [TGSI_OPCODE_EX2] = {false, false, 0, 1, 1},
   [TGSI_OPCODE_FLR] = {false, false, 0, 1, 1},
   [TGSI_OPCODE_FRC] = {false, false, 0, 1, 1},
   [TGSI_OPCODE_KILL_IF] = {false, false, 0, 0, 1},
   [TGSI_OPCODE_KILL] = {false, false, 0, 0, 0},
   [TGSI_OPCODE_LG2] = {false, false, 0, 1, 1},
   [TGSI_OPCODE_LIT] = {false, false, 0, 1, 1},
   [TGSI_OPCODE_LRP] = {false, false, 0, 1, 3},
   [TGSI_OPCODE_MAX] = {false, false, 0, 1, 2},
   [TGSI_OPCODE_MAD] = {false, false, 0, 1, 3},
   [TGSI_OPCODE_MIN] = {false, false, 0, 1, 2},
   [TGSI_OPCODE_MOV] = {false, false, 0, 1, 1},
   [TGSI_OPCODE_MUL] = {false, true, TGSI_SWIZZLE_ONE, 1, 2},
   [TGSI_OPCODE_NOP] = {false, false, 0, 0, 0},
   [TGSI_OPCODE_POW] = {false, false, 0, 1, 2},
   [TGSI_OPCODE_RCP] = {false, false, 0, 1, 1},
   [TGSI_OPCODE_RET] = {false, false, 0, 0, 0},
   [TGSI_OPCODE_RSQ] = {false, false, 0, 1, 1},
   [TGSI_OPCODE_SEQ] = {false, false, 0, 1, 2},
   [TGSI_OPCODE_SGE] = {false, false, 0, 1, 2},
   [TGSI_OPCODE_SGT] = {false, false, 0, 1, 2},
   [TGSI_OPCODE_SIN] = {false, false, 0, 1, 1},
   [TGSI_OPCODE_SLE] = {false, false, 0, 1, 2},
   [TGSI_OPCODE_SLT] = {false, false, 0, 1, 2},
   [TGSI_OPCODE_SNE] = {false, false, 0, 1, 2},
   [TGSI_OPCODE_SSG] = {false, false, 0, 1, 1},
   [TGSI_OPCODE_TEX] = {true, false, 0, 1, 2},
   [TGSI_OPCODE_TRUNC] = {false, false, 0, 1, 1},
   [TGSI_OPCODE_TXB] = {true, false, 0, 1, 2},
   [TGSI_OPCODE_TXP] = {true, false, 0, 1, 2},
};

static bool
op_has_dst(unsigned opcode)
{
   return (op_table[opcode].num_dst > 0);
}

static int
op_num_dst(unsigned opcode)
{
   return op_table[opcode].num_dst;
}

static int
op_num_src(unsigned opcode)
{
   return op_table[opcode].num_src;
}

static bool
op_commutes(unsigned opcode)
{
   return op_table[opcode].commutes;
}

static bool
is_unswizzled(struct i915_full_src_register *r, unsigned write_mask)
{
   if (write_mask & TGSI_WRITEMASK_X && r->Register.SwizzleX != TGSI_SWIZZLE_X)
      return false;
   if (write_mask & TGSI_WRITEMASK_Y && r->Register.SwizzleY != TGSI_SWIZZLE_Y)
      return false;
   if (write_mask & TGSI_WRITEMASK_Z && r->Register.SwizzleZ != TGSI_SWIZZLE_Z)
      return false;
   if (write_mask & TGSI_WRITEMASK_W && r->Register.SwizzleW != TGSI_SWIZZLE_W)
      return false;
   return true;
}

static bool
op_is_texture(unsigned opcode)
{
   return op_table[opcode].is_texture;
}

static unsigned
op_neutral_element(unsigned opcode)
{
   unsigned ne = op_table[opcode].neutral_element;
   if (!ne) {
      debug_printf("No neutral element for opcode %d\n", opcode);
      ne = TGSI_SWIZZLE_ZERO;
   }
   return ne;
}

/*
 * Sets the swizzle to the neutral element for the operation for the bits
 * of writemask which are set, swizzle to identity otherwise.
 */
static void
set_neutral_element_swizzle(struct i915_full_src_register *r,
                            unsigned write_mask, unsigned neutral)
{
   if (write_mask & TGSI_WRITEMASK_X)
      r->Register.SwizzleX = neutral;
   else
      r->Register.SwizzleX = TGSI_SWIZZLE_X;

   if (write_mask & TGSI_WRITEMASK_Y)
      r->Register.SwizzleY = neutral;
   else
      r->Register.SwizzleY = TGSI_SWIZZLE_Y;

   if (write_mask & TGSI_WRITEMASK_Z)
      r->Register.SwizzleZ = neutral;
   else
      r->Register.SwizzleZ = TGSI_SWIZZLE_Z;

   if (write_mask & TGSI_WRITEMASK_W)
      r->Register.SwizzleW = neutral;
   else
      r->Register.SwizzleW = TGSI_SWIZZLE_W;
}

static void
copy_src_reg(struct i915_src_register *o, const struct tgsi_src_register *i)
{
   o->File = i->File;
   o->Indirect = i->Indirect;
   o->Dimension = i->Dimension;
   o->Index = i->Index;
   o->SwizzleX = i->SwizzleX;
   o->SwizzleY = i->SwizzleY;
   o->SwizzleZ = i->SwizzleZ;
   o->SwizzleW = i->SwizzleW;
   o->Absolute = i->Absolute;
   o->Negate = i->Negate;
}

static void
copy_dst_reg(struct i915_dst_register *o, const struct tgsi_dst_register *i)
{
   o->File = i->File;
   o->WriteMask = i->WriteMask;
   o->Indirect = i->Indirect;
   o->Dimension = i->Dimension;
   o->Index = i->Index;
}

static void
copy_instruction(struct i915_full_instruction *o,
                 const struct tgsi_full_instruction *i)
{
   memcpy(&o->Instruction, &i->Instruction, sizeof(o->Instruction));
   memcpy(&o->Texture, &i->Texture, sizeof(o->Texture));

   copy_dst_reg(&o->Dst[0].Register, &i->Dst[0].Register);

   copy_src_reg(&o->Src[0].Register, &i->Src[0].Register);
   copy_src_reg(&o->Src[1].Register, &i->Src[1].Register);
   copy_src_reg(&o->Src[2].Register, &i->Src[2].Register);
}

static void
copy_token(union i915_full_token *o, union tgsi_full_token *i)
{
   if (i->Token.Type != TGSI_TOKEN_TYPE_INSTRUCTION)
      memcpy(o, i, sizeof(*o));
   else
      copy_instruction(&o->FullInstruction, &i->FullInstruction);
}

static void
liveness_mark_written(struct i915_optimize_context *ctx,
                      struct i915_full_dst_register *dst_reg, int pos)
{
   int dst_reg_index;
   if (dst_reg->Register.File == TGSI_FILE_TEMPORARY) {
      dst_reg_index = dst_reg->Register.Index;
      assert(dst_reg_index < TGSI_EXEC_NUM_TEMPS);
      /* dead -> live transition */
      if (ctx->first_write[dst_reg_index] != -1)
         ctx->first_write[dst_reg_index] = pos;
   }
}

static void
liveness_mark_read(struct i915_optimize_context *ctx,
                   struct i915_full_src_register *src_reg, int pos)
{
   int src_reg_index;
   if (src_reg->Register.File == TGSI_FILE_TEMPORARY) {
      src_reg_index = src_reg->Register.Index;
      assert(src_reg_index < TGSI_EXEC_NUM_TEMPS);
      /* live -> dead transition */
      if (ctx->last_read[src_reg_index] != -1)
         ctx->last_read[src_reg_index] = pos;
   }
}

static void
liveness_analysis(struct i915_optimize_context *ctx,
                  struct i915_token_list *tokens)
{
   struct i915_full_dst_register *dst_reg;
   struct i915_full_src_register *src_reg;
   union i915_full_token *current;
   unsigned opcode;
   int num_dst, num_src;
   int i = 0;

   for (i = 0; i < TGSI_EXEC_NUM_TEMPS; i++) {
      ctx->first_write[i] = -1;
      ctx->last_read[i] = -1;
   }

   for (i = 0; i < tokens->NumTokens; i++) {
      current = &tokens->Tokens[i];

      if (current->Token.Type != TGSI_TOKEN_TYPE_INSTRUCTION)
         continue;

      opcode = current->FullInstruction.Instruction.Opcode;
      num_dst = op_num_dst(opcode);

      switch (num_dst) {
      case 1:
         dst_reg = &current->FullInstruction.Dst[0];
         liveness_mark_written(ctx, dst_reg, i);
         FALLTHROUGH;
      case 0:
         break;
      default:
         debug_printf("Op %d has %d dst regs\n", opcode, num_dst);
         break;
      }
   }

   for (i = tokens->NumTokens - 1; i >= 0; i--) {
      current = &tokens->Tokens[i];

      if (current->Token.Type != TGSI_TOKEN_TYPE_INSTRUCTION)
         continue;

      opcode = current->FullInstruction.Instruction.Opcode;
      num_src = op_num_src(opcode);

      switch (num_src) {
      case 3:
         src_reg = &current->FullInstruction.Src[2];
         liveness_mark_read(ctx, src_reg, i);
         FALLTHROUGH;
      case 2:
         src_reg = &current->FullInstruction.Src[1];
         liveness_mark_read(ctx, src_reg, i);
         FALLTHROUGH;
      case 1:
         src_reg = &current->FullInstruction.Src[0];
         liveness_mark_read(ctx, src_reg, i);
         FALLTHROUGH;
      case 0:
         break;
      default:
         debug_printf("Op %d has %d src regs\n", opcode, num_src);
         break;
      }
   }
}

static int
unused_from(struct i915_optimize_context *ctx,
            struct i915_full_dst_register *dst_reg, int from)
{
   int dst_reg_index = dst_reg->Register.Index;
   assert(dst_reg_index < TGSI_EXEC_NUM_TEMPS);
   return (from >= ctx->last_read[dst_reg_index]);
}

/* Returns a mask with the components used for a texture access instruction */
static unsigned
i915_tex_mask(union i915_full_token *instr)
{
   return i915_coord_mask(instr->FullInstruction.Instruction.Opcode,
                          instr->FullInstruction.Texture.Texture);
}

static bool
target_is_texture2d(uint32_t tex)
{
   switch (tex) {
   case TGSI_TEXTURE_2D:
   case TGSI_TEXTURE_RECT:
      return true;
   default:
      return false;
   }
}

/*
 * Optimize away useless indirect texture reads:
 *    MOV TEMP[0].xy, IN[0].xyyy
 *    TEX TEMP[1], TEMP[0], SAMP[0], 2D
 * into:
 *    TEX TEMP[1], IN[0], SAMP[0], 2D
 *
 * note: this only seems to work on 2D/RECT textures, but not SHAADOW2D/1D/..
 */
static void
i915_fpc_optimize_mov_before_tex(struct i915_optimize_context *ctx,
                                 struct i915_token_list *tokens, int index)
{
   union i915_full_token *current = &tokens->Tokens[index - 1];
   union i915_full_token *next = &tokens->Tokens[index];

   if (current->Token.Type == TGSI_TOKEN_TYPE_INSTRUCTION &&
       next->Token.Type == TGSI_TOKEN_TYPE_INSTRUCTION &&
       current->FullInstruction.Instruction.Opcode == TGSI_OPCODE_MOV &&
       op_is_texture(next->FullInstruction.Instruction.Opcode) &&
       target_is_texture2d(next->FullInstruction.Texture.Texture) &&
       same_src_dst_reg(&next->FullInstruction.Src[0],
                        &current->FullInstruction.Dst[0]) &&
       is_unswizzled(&current->FullInstruction.Src[0], i915_tex_mask(next)) &&
       unused_from(ctx, &current->FullInstruction.Dst[0], index)) {
      memcpy(&next->FullInstruction.Src[0], &current->FullInstruction.Src[0],
             sizeof(struct i915_src_register));
      current->FullInstruction.Instruction.Opcode = TGSI_OPCODE_NOP;
   }
}

/*
 * Optimize away things like:
 *    MOV TEMP[0].xy, TEMP[1].xyyy (first write for TEMP[0])
 *    MOV TEMP[0].w, TEMP[1].wwww (last write for TEMP[0])
 * into:
 *    NOP
 *    MOV OUT[0].xyw, TEMP[1].xyww
 */
static void
i915_fpc_optimize_mov_after_mov(union i915_full_token *current,
                                union i915_full_token *next)
{
   struct i915_full_src_register *src_reg1, *src_reg2;
   struct i915_full_dst_register *dst_reg1, *dst_reg2;
   unsigned swizzle_x, swizzle_y, swizzle_z, swizzle_w;

   if (current->Token.Type == TGSI_TOKEN_TYPE_INSTRUCTION &&
       next->Token.Type == TGSI_TOKEN_TYPE_INSTRUCTION &&
       current->FullInstruction.Instruction.Opcode == TGSI_OPCODE_MOV &&
       next->FullInstruction.Instruction.Opcode == TGSI_OPCODE_MOV &&
       current->FullInstruction.Instruction.Saturate ==
          next->FullInstruction.Instruction.Saturate &&
       same_dst_reg(&next->FullInstruction.Dst[0],
                    &current->FullInstruction.Dst[0]) &&
       same_src_reg(&next->FullInstruction.Src[0],
                    &current->FullInstruction.Src[0]) &&
       !same_src_dst_reg(&current->FullInstruction.Src[0],
                         &current->FullInstruction.Dst[0])) {
      src_reg1 = &current->FullInstruction.Src[0];
      dst_reg1 = &current->FullInstruction.Dst[0];
      src_reg2 = &next->FullInstruction.Src[0];
      dst_reg2 = &next->FullInstruction.Dst[0];

      /* Start with swizzles from the first mov */
      swizzle_x = src_reg1->Register.SwizzleX;
      swizzle_y = src_reg1->Register.SwizzleY;
      swizzle_z = src_reg1->Register.SwizzleZ;
      swizzle_w = src_reg1->Register.SwizzleW;

      /* Pile the second mov on top */
      if (dst_reg2->Register.WriteMask & TGSI_WRITEMASK_X)
         swizzle_x = src_reg2->Register.SwizzleX;
      if (dst_reg2->Register.WriteMask & TGSI_WRITEMASK_Y)
         swizzle_y = src_reg2->Register.SwizzleY;
      if (dst_reg2->Register.WriteMask & TGSI_WRITEMASK_Z)
         swizzle_z = src_reg2->Register.SwizzleZ;
      if (dst_reg2->Register.WriteMask & TGSI_WRITEMASK_W)
         swizzle_w = src_reg2->Register.SwizzleW;

      dst_reg2->Register.WriteMask |= dst_reg1->Register.WriteMask;
      src_reg2->Register.SwizzleX = swizzle_x;
      src_reg2->Register.SwizzleY = swizzle_y;
      src_reg2->Register.SwizzleZ = swizzle_z;
      src_reg2->Register.SwizzleW = swizzle_w;

      current->FullInstruction.Instruction.Opcode = TGSI_OPCODE_NOP;

      return;
   }
}

/*
 * Optimize away things like:
 *    MUL OUT[0].xyz, TEMP[1], TEMP[2]
 *    MOV OUT[0].w, TEMP[2]
 * into:
 *    MUL OUT[0].xyzw, TEMP[1].xyz1, TEMP[2]
 * This is useful for optimizing texenv.
 */
static void
i915_fpc_optimize_mov_after_alu(union i915_full_token *current,
                                union i915_full_token *next)
{
   if (current->Token.Type == TGSI_TOKEN_TYPE_INSTRUCTION &&
       next->Token.Type == TGSI_TOKEN_TYPE_INSTRUCTION &&
       op_commutes(current->FullInstruction.Instruction.Opcode) &&
       current->FullInstruction.Instruction.Saturate ==
          next->FullInstruction.Instruction.Saturate &&
       next->FullInstruction.Instruction.Opcode == TGSI_OPCODE_MOV &&
       same_dst_reg(&next->FullInstruction.Dst[0],
                    &current->FullInstruction.Dst[0]) &&
       same_src_reg(&next->FullInstruction.Src[0],
                    &current->FullInstruction.Src[1]) &&
       !same_src_dst_reg(&next->FullInstruction.Src[0],
                         &current->FullInstruction.Dst[0]) &&
       is_unswizzled(&current->FullInstruction.Src[0],
                     current->FullInstruction.Dst[0].Register.WriteMask) &&
       is_unswizzled(&current->FullInstruction.Src[1],
                     current->FullInstruction.Dst[0].Register.WriteMask) &&
       is_unswizzled(&next->FullInstruction.Src[0],
                     next->FullInstruction.Dst[0].Register.WriteMask)) {
      next->FullInstruction.Instruction.Opcode = TGSI_OPCODE_NOP;

      set_neutral_element_swizzle(&current->FullInstruction.Src[1], 0, 0);
      set_neutral_element_swizzle(
         &current->FullInstruction.Src[0],
         next->FullInstruction.Dst[0].Register.WriteMask,
         op_neutral_element(current->FullInstruction.Instruction.Opcode));

      current->FullInstruction.Dst[0].Register.WriteMask =
         current->FullInstruction.Dst[0].Register.WriteMask |
         next->FullInstruction.Dst[0].Register.WriteMask;
      return;
   }

   if (current->Token.Type == TGSI_TOKEN_TYPE_INSTRUCTION &&
       next->Token.Type == TGSI_TOKEN_TYPE_INSTRUCTION &&
       op_commutes(current->FullInstruction.Instruction.Opcode) &&
       current->FullInstruction.Instruction.Saturate ==
          next->FullInstruction.Instruction.Saturate &&
       next->FullInstruction.Instruction.Opcode == TGSI_OPCODE_MOV &&
       same_dst_reg(&next->FullInstruction.Dst[0],
                    &current->FullInstruction.Dst[0]) &&
       same_src_reg(&next->FullInstruction.Src[0],
                    &current->FullInstruction.Src[0]) &&
       !same_src_dst_reg(&next->FullInstruction.Src[0],
                         &current->FullInstruction.Dst[0]) &&
       is_unswizzled(&current->FullInstruction.Src[0],
                     current->FullInstruction.Dst[0].Register.WriteMask) &&
       is_unswizzled(&current->FullInstruction.Src[1],
                     current->FullInstruction.Dst[0].Register.WriteMask) &&
       is_unswizzled(&next->FullInstruction.Src[0],
                     next->FullInstruction.Dst[0].Register.WriteMask)) {
      next->FullInstruction.Instruction.Opcode = TGSI_OPCODE_NOP;

      set_neutral_element_swizzle(&current->FullInstruction.Src[0], 0, 0);
      set_neutral_element_swizzle(
         &current->FullInstruction.Src[1],
         next->FullInstruction.Dst[0].Register.WriteMask,
         op_neutral_element(current->FullInstruction.Instruction.Opcode));

      current->FullInstruction.Dst[0].Register.WriteMask =
         current->FullInstruction.Dst[0].Register.WriteMask |
         next->FullInstruction.Dst[0].Register.WriteMask;
      return;
   }
}

/*
 * Optimize away things like:
 *    MOV TEMP[0].xyz TEMP[0].xyzx
 * into:
 *    NOP
 */
static bool
i915_fpc_useless_mov(union tgsi_full_token *tgsi_current)
{
   union i915_full_token current;
   copy_token(&current, tgsi_current);
   if (current.Token.Type == TGSI_TOKEN_TYPE_INSTRUCTION &&
       current.FullInstruction.Instruction.Opcode == TGSI_OPCODE_MOV &&
       op_has_dst(current.FullInstruction.Instruction.Opcode) &&
       !current.FullInstruction.Instruction.Saturate &&
       current.FullInstruction.Src[0].Register.Absolute == 0 &&
       current.FullInstruction.Src[0].Register.Negate == 0 &&
       is_unswizzled(&current.FullInstruction.Src[0],
                     current.FullInstruction.Dst[0].Register.WriteMask) &&
       same_src_dst_reg(&current.FullInstruction.Src[0],
                        &current.FullInstruction.Dst[0])) {
      return true;
   }
   return false;
}

/*
 * Optimize away things like:
 *    *** TEMP[0], TEMP[1], TEMP[2]
 *    MOV OUT[0] TEMP[0]
 * into:
 *    *** OUT[0], TEMP[1], TEMP[2]
 */
static void
i915_fpc_optimize_useless_mov_after_inst(struct i915_optimize_context *ctx,
                                         struct i915_token_list *tokens,
                                         int index)
{
   union i915_full_token *current = &tokens->Tokens[index - 1];
   union i915_full_token *next = &tokens->Tokens[index];

   // &out_tokens->Tokens[i-1], &out_tokens->Tokens[i]);
   if (current->Token.Type == TGSI_TOKEN_TYPE_INSTRUCTION &&
       next->Token.Type == TGSI_TOKEN_TYPE_INSTRUCTION &&
       next->FullInstruction.Instruction.Opcode == TGSI_OPCODE_MOV &&
       op_has_dst(current->FullInstruction.Instruction.Opcode) &&
       !next->FullInstruction.Instruction.Saturate &&
       next->FullInstruction.Src[0].Register.Absolute == 0 &&
       next->FullInstruction.Src[0].Register.Negate == 0 &&
       unused_from(ctx, &current->FullInstruction.Dst[0], index) &&
       current->FullInstruction.Dst[0].Register.WriteMask ==
          TGSI_WRITEMASK_XYZW &&
       is_unswizzled(&next->FullInstruction.Src[0],
                     next->FullInstruction.Dst[0].Register.WriteMask) &&
       current->FullInstruction.Dst[0].Register.WriteMask ==
          next->FullInstruction.Dst[0].Register.WriteMask &&
       same_src_dst_reg(&next->FullInstruction.Src[0],
                        &current->FullInstruction.Dst[0])) {
      next->FullInstruction.Instruction.Opcode = TGSI_OPCODE_NOP;

      current->FullInstruction.Dst[0] = next->FullInstruction.Dst[0];
      return;
   }
}

struct i915_token_list *
i915_optimize(const struct tgsi_token *tokens)
{
   struct i915_token_list *out_tokens = MALLOC(sizeof(struct i915_token_list));
   struct tgsi_parse_context parse;
   struct i915_optimize_context *ctx;
   int i = 0;

   ctx = malloc(sizeof(*ctx));

   out_tokens->NumTokens = 0;

   /* Count the tokens */
   tgsi_parse_init(&parse, tokens);
   while (!tgsi_parse_end_of_tokens(&parse)) {
      tgsi_parse_token(&parse);
      out_tokens->NumTokens++;
   }
   tgsi_parse_free(&parse);

   /* Allocate our tokens */
   out_tokens->Tokens =
      MALLOC(sizeof(union i915_full_token) * out_tokens->NumTokens);

   tgsi_parse_init(&parse, tokens);
   while (!tgsi_parse_end_of_tokens(&parse)) {
      tgsi_parse_token(&parse);

      if (i915_fpc_useless_mov(&parse.FullToken)) {
         out_tokens->NumTokens--;
         continue;
      }

      copy_token(&out_tokens->Tokens[i], &parse.FullToken);

      i++;
   }
   tgsi_parse_free(&parse);

   liveness_analysis(ctx, out_tokens);

   i = 1;
   while (i < out_tokens->NumTokens) {
      i915_fpc_optimize_useless_mov_after_inst(ctx, out_tokens, i);
      i915_fpc_optimize_mov_after_alu(&out_tokens->Tokens[i - 1],
                                      &out_tokens->Tokens[i]);
      i915_fpc_optimize_mov_after_mov(&out_tokens->Tokens[i - 1],
                                      &out_tokens->Tokens[i]);
      i915_fpc_optimize_mov_before_tex(ctx, out_tokens, i);
      i++;
   }

   free(ctx);

   return out_tokens;
}

void
i915_optimize_free(struct i915_token_list *tokens)
{
   free(tokens->Tokens);
   free(tokens);
}