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author | Matt Turner <mattst88@gmail.com> | 2013-10-30 10:32:12 -0700 |
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committer | Matt Turner <mattst88@gmail.com> | 2013-11-20 15:04:53 -0800 |
commit | a97cd0f4d7902965d5173f4bcbf2ad27c0eb5d12 (patch) | |
tree | f13be7d77a5908054bb89c5793648bf94feb045e /src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp | |
parent | b63d6aae55c06bf7cb6b9ed1370634bc120ed045 (diff) | |
download | external_mesa3d-a97cd0f4d7902965d5173f4bcbf2ad27c0eb5d12.zip external_mesa3d-a97cd0f4d7902965d5173f4bcbf2ad27c0eb5d12.tar.gz external_mesa3d-a97cd0f4d7902965d5173f4bcbf2ad27c0eb5d12.tar.bz2 |
i965: Add a pass to remove dead control flow.
Removes IF/ENDIF and IF/ELSE/ENDIF with no intervening instructions.
total instructions in shared programs: 1360393 -> 1360387 (-0.00%)
instructions in affected programs: 157 -> 151 (-3.82%)
(no change in vertex shaders)
Reviewed-by: Paul Berry <stereotype441@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Diffstat (limited to 'src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp')
-rw-r--r-- | src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp b/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp new file mode 100644 index 0000000..8bdf094 --- /dev/null +++ b/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp @@ -0,0 +1,83 @@ +/* + * Copyright © 2013 Intel Corporation + * + * 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, sublicense, + * 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 NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS 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 brw_dead_control_flow.cpp + * + * This file implements the dead control flow elimination optimization pass. + */ + +#include "brw_shader.h" +#include "brw_cfg.h" + +/* Look for and eliminate dead control flow: + * + * - if/endif + * - if/else/endif + */ +bool +dead_control_flow_eliminate(backend_visitor *v) +{ + bool progress = false; + + cfg_t cfg(v); + + for (int b = 0; b < cfg.num_blocks; b++) { + bblock_t *block = cfg.blocks[b]; + bool found = false; + + /* ENDIF instructions, by definition, can only be found at the ends of + * basic blocks. + */ + backend_instruction *endif_inst = block->end; + if (endif_inst->opcode != BRW_OPCODE_ENDIF) + continue; + + backend_instruction *if_inst = NULL, *else_inst = NULL; + backend_instruction *prev_inst = (backend_instruction *) endif_inst->prev; + if (prev_inst->opcode == BRW_OPCODE_IF) { + if_inst = prev_inst; + found = true; + } else if (prev_inst->opcode == BRW_OPCODE_ELSE) { + else_inst = prev_inst; + + prev_inst = (backend_instruction *) prev_inst->prev; + if (prev_inst->opcode == BRW_OPCODE_IF) { + if_inst = prev_inst; + found = true; + } + } + + if (found) { + if_inst->remove(); + if (else_inst) + else_inst->remove(); + endif_inst->remove(); + progress = true; + } + } + + if (progress) + v->invalidate_live_intervals(); + + return progress; +} |