src/mesa/drivers/dri/i965/brw_cfg.cpp

   1 /*
   2  * Copyright © 2012 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  *
  23  * Authors:
  24  *    Eric Anholt <eric@anholt.net>
  25  *
  26  */
  27
  28 #include "brw_fs.h"
  29 #include "brw_cfg.h"
  30
  31 /** @file brw_cfg_t.cpp
  32  *
  33  * Walks the shader instructions generated and creates a set of basic
  34  * blocks with successor/predecessor edges connecting them.
  35  */
  36
  37 static bblock_t *
  38 pop_stack(exec_list *list)
  39 {
  40    bblock_link *link = (bblock_link *)list->get_tail();
  41    bblock_t *block = link->block;
  42    link->remove();
  43
  44    return block;
  45 }
  46
  47 bblock_t::bblock_t()
  48 {
  49    start = NULL;
  50    end = NULL;
  51
  52    parents.make_empty();
  53    children.make_empty();
  54 }
  55
  56 void
  57 bblock_t::add_successor(void *mem_ctx, bblock_t *successor)
  58 {
  59    successor->parents.push_tail(this->make_list(mem_ctx));
  60    children.push_tail(successor->make_list(mem_ctx));
  61 }
  62
  63 bblock_link *
  64 bblock_t::make_list(void *mem_ctx)
  65 {
  66    return new(mem_ctx) bblock_link(this);
  67 }
  68
  69 cfg_t::cfg_t(fs_visitor *v)
  70 {
  71    mem_ctx = ralloc_context(v->mem_ctx);
  72    block_list.make_empty();
  73    num_blocks = 0;
  74    ip = 0;
  75    cur = NULL;
  76
  77    bblock_t *entry = new_block();
  78    bblock_t *cur_if = NULL, *cur_else = NULL, *cur_endif = NULL;
  79    bblock_t *cur_do = NULL, *cur_while = NULL;
  80    exec_list if_stack, else_stack, endif_stack, do_stack, while_stack;
  81    bblock_t *next;
  82
  83    set_next_block(entry);
  84
  85    entry->start = (fs_inst *)v->instructions.get_head();
  86
  87    foreach_list(node, &v->instructions) {
  88       fs_inst *inst = (fs_inst *)node;
  89
  90       cur->end = inst;
  91
  92       /* set_next_block wants the post-incremented ip */
  93       ip++;
  94
  95       switch (inst->opcode) {
  96       case BRW_OPCODE_IF:
  97          /* Push our information onto a stack so we can recover from
  98           * nested ifs.
  99           */
 100          if_stack.push_tail(cur_if->make_list(mem_ctx));
 101          else_stack.push_tail(cur_else->make_list(mem_ctx));
 102          endif_stack.push_tail(cur_endif->make_list(mem_ctx));
 103
 104          cur_if = cur;
 105          cur_else = NULL;
 106          /* Set up the block just after the endif.  Don't know when exactly
 107           * it will start, yet.
 108           */
 109          cur_endif = new_block();
 110
 111          /* Set up our immediately following block, full of "then"
 112           * instructions.
 113           */
 114          next = new_block();
 115          next->start = (fs_inst *)inst->next;
 116          cur_if->add_successor(mem_ctx, next);
 117
 118          set_next_block(next);
 119          break;
 120
 121       case BRW_OPCODE_ELSE:
 122          cur->add_successor(mem_ctx, cur_endif);
 123
 124          next = new_block();
 125          next->start = (fs_inst *)inst->next;
 126          cur_if->add_successor(mem_ctx, next);
 127          cur_else = next;
 128
 129          set_next_block(next);
 130          break;
 131
 132       case BRW_OPCODE_ENDIF:
 133          cur_endif->start = (fs_inst *)inst->next;
 134          cur->add_successor(mem_ctx, cur_endif);
 135          set_next_block(cur_endif);
 136
 137          if (!cur_else)
 138             cur_if->add_successor(mem_ctx, cur_endif);
 139
 140          /* Pop the stack so we're in the previous if/else/endif */
 141          cur_if = pop_stack(&if_stack);
 142          cur_else = pop_stack(&else_stack);
 143          cur_endif = pop_stack(&endif_stack);
 144          break;
 145
 146       case BRW_OPCODE_DO:
 147          /* Push our information onto a stack so we can recover from
 148           * nested loops.
 149           */
 150          do_stack.push_tail(cur_do->make_list(mem_ctx));
 151          while_stack.push_tail(cur_while->make_list(mem_ctx));
 152
 153          /* Set up the block just after the while.  Don't know when exactly
 154           * it will start, yet.
 155           */
 156          cur_while = new_block();
 157
 158          /* Set up our immediately following block, full of "then"
 159           * instructions.
 160           */
 161          next = new_block();
 162          next->start = (fs_inst *)inst->next;
 163          cur->add_successor(mem_ctx, next);
 164          cur_do = next;
 165
 166          set_next_block(next);
 167          break;
 168
 169       case BRW_OPCODE_CONTINUE:
 170          cur->add_successor(mem_ctx, cur_do);
 171
 172          next = new_block();
 173          next->start = (fs_inst *)inst->next;
 174          if (inst->predicated)
 175             cur->add_successor(mem_ctx, next);
 176
 177          set_next_block(next);
 178          break;
 179
 180       case BRW_OPCODE_BREAK:
 181          cur->add_successor(mem_ctx, cur_while);
 182
 183          next = new_block();
 184          next->start = (fs_inst *)inst->next;
 185          if (inst->predicated)
 186             cur->add_successor(mem_ctx, next);
 187
 188          set_next_block(next);
 189          break;
 190
 191       case BRW_OPCODE_WHILE:
 192          cur_while->start = (fs_inst *)inst->next;
 193
 194          cur->add_successor(mem_ctx, cur_do);
 195          set_next_block(cur_while);
 196
 197          /* Pop the stack so we're in the previous loop */
 198          cur_do = pop_stack(&do_stack);
 199          cur_while = pop_stack(&while_stack);
 200          break;
 201
 202       default:
 203          break;
 204       }
 205    }
 206
 207    cur->end_ip = ip;
 208
 209    make_block_array();
 210 }
 211
 212 cfg_t::~cfg_t()
 213 {
 214    ralloc_free(mem_ctx);
 215 }
 216
 217 bblock_t *
 218 cfg_t::new_block()
 219 {
 220    bblock_t *block = new(mem_ctx) bblock_t();
 221
 222    return block;
 223 }
 224
 225 void
 226 cfg_t::set_next_block(bblock_t *block)
 227 {
 228    if (cur) {
 229       assert(cur->end->next == block->start);
 230       cur->end_ip = ip - 1;
 231    }
 232
 233    block->start_ip = ip;
 234    block->block_num = num_blocks++;
 235    block_list.push_tail(block->make_list(mem_ctx));
 236    cur = block;
 237 }
 238
 239 void
 240 cfg_t::make_block_array()
 241 {
 242    blocks = ralloc_array(mem_ctx, bblock_t *, num_blocks);
 243
 244    int i = 0;
 245    foreach_list(block_node, &block_list) {
 246       bblock_link *link = (bblock_link *)block_node;
 247       blocks[i++] = link->block;
 248    }
 249    assert(i == num_blocks);
 250 }