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e8308d0523
This replaces an O(n^2) algorithm with an O(n) one, while allowing us to
import most of the infrastructure required for GVN. The idea is to walk
the dominance tree depth-first, similar when converting to SSA, and
remove the instructions from the set when we're done visiting the
sub-tree of the dominance tree so that the only instructions in the set
are the instructions that dominate the current block.
No piglit regressions. No shader-db changes.
Compilation time for full shader-db:
Difference at 95.0% confidence
-35.826 +/- 2.16018
-6.2852% +/- 0.378975%
(Student's t, pooled s = 3.37504)
v2:
- rebase on start_block removal
- remove useless state struct
- change commit message
Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>
Signed-off-by: Connor Abbott <cwabbott0@gmail.com>
93 lines
2.7 KiB
C
93 lines
2.7 KiB
C
/*
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* Copyright © 2014 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*
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* Authors:
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* Jason Ekstrand (jason@jlekstrand.net)
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* Connor Abbott (cwabbott0@gmail.com)
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*
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*/
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#include "nir_instr_set.h"
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/*
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* Implements common subexpression elimination
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*/
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/*
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* Visits and CSE's the given block and all its descendants in the dominance
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* tree recursively. Note that the instr_set is guaranteed to only ever
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* contain instructions that dominate the current block.
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*/
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static bool
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cse_block(nir_block *block, struct set *instr_set)
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{
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bool progress = false;
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nir_foreach_instr_safe(block, instr) {
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if (nir_instr_set_add_or_rewrite(instr_set, instr)) {
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progress = true;
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nir_instr_remove(instr);
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}
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}
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for (unsigned i = 0; i < block->num_dom_children; i++) {
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nir_block *child = block->dom_children[i];
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progress |= cse_block(child, instr_set);
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}
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nir_foreach_instr(block, instr)
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nir_instr_set_remove(instr_set, instr);
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return progress;
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}
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static bool
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nir_opt_cse_impl(nir_function_impl *impl)
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{
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struct set *instr_set = nir_instr_set_create(NULL);
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nir_metadata_require(impl, nir_metadata_dominance);
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bool progress = cse_block(nir_start_block(impl), instr_set);
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if (progress)
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nir_metadata_preserve(impl, nir_metadata_block_index |
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nir_metadata_dominance);
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nir_instr_set_destroy(instr_set);
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return progress;
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}
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bool
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nir_opt_cse(nir_shader *shader)
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{
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bool progress = false;
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nir_foreach_overload(shader, overload) {
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if (overload->impl)
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progress |= nir_opt_cse_impl(overload->impl);
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}
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return progress;
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}
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