src/panfrost/bifrost/bifrost_opts.c

   1 /*
   2  * Copyright (C) 2019 Ryan Houdek <Sonicadvance1@gmail.com>
   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 FROM,
  20  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  21  * SOFTWARE.
  22  */
  23
  24 #include "bifrost_opts.h"
  25 #include "compiler_defines.h"
  26
  27 bool
  28 bifrost_opt_branch_fusion(compiler_context *ctx, bifrost_block *block)
  29 {
  30         bool progress = false;
  31         mir_foreach_instr_in_block_safe(block, instr) {
  32                 if (instr->op != op_branch) continue;
  33                 if (instr->literal_args[0] != BR_COND_EQ) continue;
  34
  35                 unsigned src1 = instr->ssa_args.src0;
  36
  37                 // Only work on SSA values
  38                 if (src1 >= SSA_FIXED_MINIMUM) continue;
  39
  40                 // Find the source for this conditional branch instruction
  41                 // It'll be a CSEL instruction
  42                 // If it's comparision is one of the ops that our conditional branch supports
  43                 // then we can merge the two
  44                 mir_foreach_instr_in_block_from_rev(block, next_instr, instr) {
  45                         if (next_instr->op != op_csel_i32) continue;
  46
  47                         if (next_instr->ssa_args.dest == src1) {
  48                                 // We found the CSEL instruction that is the source here
  49                                 // Check its condition to make sure it matches what we can fuse
  50                                 unsigned cond = next_instr->literal_args[0];
  51                                 if (cond == CSEL_IEQ) {
  52                                         // This CSEL is doing an IEQ for our conditional branch doing EQ
  53                                         // We can just emit a conditional branch that does the comparison
  54                                         struct bifrost_instruction new_instr = {
  55                                                 .op = op_branch,
  56                                                 .dest_components = 0,
  57                                                 .ssa_args = {
  58                                                         .dest = SSA_INVALID_VALUE,
  59                                                         .src0 = next_instr->ssa_args.src0,
  60                                                         .src1 = next_instr->ssa_args.src1,
  61                                                         .src2 = SSA_INVALID_VALUE,
  62                                                         .src3 = SSA_INVALID_VALUE,
  63                                                 },
  64                                                 .literal_args[0] = BR_COND_EQ,
  65                                                 .literal_args[1] = instr->literal_args[1],
  66                                         };
  67                                         mir_insert_instr_before(instr, new_instr);
  68                                         mir_remove_instr(instr);
  69                                         progress |= true;
  70                                         break;
  71                                 }
  72                         }
  73                 }
  74         }
  75
  76         return progress;
  77 }
  78