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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)
*
*/
#include "nir_instr_set.h"
/*
* Implements common subexpression elimination
*/
struct cse_state {
void *mem_ctx;
bool progress;
};
static bool
src_is_ssa(nir_src *src, void *data)
{
(void) data;
return src->is_ssa;
}
static bool
dest_is_ssa(nir_dest *dest, void *data)
{
(void) data;
return dest->is_ssa;
}
static bool
nir_instr_can_cse(nir_instr *instr)
{
/* We only handle SSA. */
if (!nir_foreach_dest(instr, dest_is_ssa, NULL) ||
!nir_foreach_src(instr, src_is_ssa, NULL))
return false;
switch (instr->type) {
case nir_instr_type_alu:
case nir_instr_type_tex:
case nir_instr_type_load_const:
case nir_instr_type_phi:
return true;
case nir_instr_type_intrinsic: {
const nir_intrinsic_info *info =
&nir_intrinsic_infos[nir_instr_as_intrinsic(instr)->intrinsic];
return (info->flags & NIR_INTRINSIC_CAN_ELIMINATE) &&
(info->flags & NIR_INTRINSIC_CAN_REORDER) &&
info->num_variables == 0; /* not implemented yet */
}
case nir_instr_type_call:
case nir_instr_type_jump:
case nir_instr_type_ssa_undef:
return false;
case nir_instr_type_parallel_copy:
default:
unreachable("Invalid instruction type");
}
return false;
}
static nir_ssa_def *
nir_instr_get_dest_ssa_def(nir_instr *instr)
{
switch (instr->type) {
case nir_instr_type_alu:
assert(nir_instr_as_alu(instr)->dest.dest.is_ssa);
return &nir_instr_as_alu(instr)->dest.dest.ssa;
case nir_instr_type_tex:
assert(nir_instr_as_tex(instr)->dest.is_ssa);
return &nir_instr_as_tex(instr)->dest.ssa;
case nir_instr_type_load_const:
return &nir_instr_as_load_const(instr)->def;
case nir_instr_type_phi:
assert(nir_instr_as_phi(instr)->dest.is_ssa);
return &nir_instr_as_phi(instr)->dest.ssa;
case nir_instr_type_intrinsic:
assert(nir_instr_as_intrinsic(instr)->dest.is_ssa);
return &nir_instr_as_intrinsic(instr)->dest.ssa;
default:
unreachable("We never ask for any of these");
}
}
static void
nir_opt_cse_instr(nir_instr *instr, struct cse_state *state)
{
if (!nir_instr_can_cse(instr))
return;
for (struct exec_node *node = instr->node.prev;
!exec_node_is_head_sentinel(node); node = node->prev) {
nir_instr *other = exec_node_data(nir_instr, node, node);
if (nir_instrs_equal(instr, other)) {
nir_ssa_def *other_def = nir_instr_get_dest_ssa_def(other);
nir_ssa_def_rewrite_uses(nir_instr_get_dest_ssa_def(instr),
nir_src_for_ssa(other_def));
nir_instr_remove(instr);
state->progress = true;
return;
}
}
for (nir_block *block = instr->block->imm_dom;
block != NULL; block = block->imm_dom) {
nir_foreach_instr_reverse(block, other) {
if (nir_instrs_equal(instr, other)) {
nir_ssa_def *other_def = nir_instr_get_dest_ssa_def(other);
nir_ssa_def_rewrite_uses(nir_instr_get_dest_ssa_def(instr),
nir_src_for_ssa(other_def));
nir_instr_remove(instr);
state->progress = true;
return;
}
}
}
}
static bool
nir_opt_cse_block(nir_block *block, void *void_state)
{
struct cse_state *state = void_state;
nir_foreach_instr_safe(block, instr)
nir_opt_cse_instr(instr, state);
return true;
}
static bool
nir_opt_cse_impl(nir_function_impl *impl)
{
struct cse_state state;
state.mem_ctx = ralloc_parent(impl);
state.progress = false;
nir_metadata_require(impl, nir_metadata_dominance);
nir_foreach_block(impl, nir_opt_cse_block, &state);
if (state.progress)
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
return state.progress;
}
bool
nir_opt_cse(nir_shader *shader)
{
bool progress = false;
nir_foreach_overload(shader, overload) {
if (overload->impl)
progress |= nir_opt_cse_impl(overload->impl);
}
return progress;
}
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