src/panfrost/midgard/midgard_opt_dce.c

   1 /*
   2  * Copyright (C) 2018 Alyssa Rosenzweig
   3  * Copyright (C) 2019 Collabora, Ltd.
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   9  * and/or sell copies of the Software, and to permit persons to whom the
  10  * Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice (including the next
  13  * paragraph) shall be included in all copies or substantial portions of the
  14  * Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  22  * SOFTWARE.
  23  */
  24
  25 #include "compiler.h"
  26
  27 /* Basic dead code elimination on the MIR itself */
  28
  29 bool
  30 midgard_opt_dead_code_eliminate(compiler_context *ctx, midgard_block *block)
  31 {
  32         bool progress = false;
  33
  34         mir_foreach_instr_in_block_safe(block, ins) {
  35                 if (ins->type != TAG_ALU_4) continue;
  36                 if (ins->compact_branch) continue;
  37
  38                 if (ins->ssa_args.dest >= SSA_FIXED_MINIMUM) continue;
  39                 if (mir_is_live_after(ctx, block, ins, ins->ssa_args.dest)) continue;
  40
  41                 mir_remove_instruction(ins);
  42                 progress = true;
  43         }
  44
  45         return progress;
  46 }