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/*
* Copyright © 2014 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.
*
* Authors:
* Jason Ekstrand (jason@jlekstrand.net)
* Connor Abbott (cwabbott0@gmail.com)
*
*/
#include "nir_instr_set.h"
/*
* Implements common subexpression elimination
*/
/*
* Visits and CSEs the given block and all its descendants in the dominance
* tree recursively. Note that the instr_set is guaranteed to only ever
* contain instructions that dominate the current block.
*/
static bool
cse_block(nir_block *block, struct set *instr_set)
{
bool progress = false;
nir_foreach_instr_safe(instr, block) {
if (nir_instr_set_add_or_rewrite(instr_set, instr)) {
progress = true;
nir_instr_remove(instr);
}
}
for (unsigned i = 0; i < block->num_dom_children; i++) {
nir_block *child = block->dom_children[i];
progress |= cse_block(child, instr_set);
}
nir_foreach_instr(instr, block)
nir_instr_set_remove(instr_set, instr);
return progress;
}
static bool
nir_opt_cse_impl(nir_function_impl *impl)
{
struct set *instr_set = nir_instr_set_create(NULL);
nir_metadata_require(impl, nir_metadata_dominance);
bool progress = cse_block(nir_start_block(impl), instr_set);
if (progress) {
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
} else {
#ifndef NDEBUG
impl->valid_metadata &= ~nir_metadata_not_properly_reset;
#endif
}
nir_instr_set_destroy(instr_set);
return progress;
}
bool
nir_opt_cse(nir_shader *shader)
{
bool progress = false;
nir_foreach_function(function, shader) {
if (function->impl)
progress |= nir_opt_cse_impl(function->impl);
}
return progress;
}
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