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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:
* Connor Abbott (cwabbott0@gmail.com)
*
*/
#include "nir.h"
static void
add_var_use_intrinsic(nir_intrinsic_instr *instr, struct set *live,
nir_variable_mode modes)
{
unsigned num_vars = nir_intrinsic_infos[instr->intrinsic].num_variables;
switch (instr->intrinsic) {
case nir_intrinsic_copy_var:
_mesa_set_add(live, instr->variables[1]->var);
/* Fall through */
case nir_intrinsic_store_var: {
/* The first source in both copy_var and store_var is the destination.
* If the variable is a local that never escapes the shader, then we
* don't mark it as live for just a store.
*/
nir_variable_mode mode = instr->variables[0]->var->data.mode;
if (!(mode & (nir_var_local | nir_var_global | nir_var_shared)))
_mesa_set_add(live, instr->variables[0]->var);
break;
}
/* This pass can't be used on I/O variables after they've been lowered. */
case nir_intrinsic_load_input:
assert(!(modes & nir_var_shader_in));
break;
case nir_intrinsic_store_output:
assert(!(modes & nir_var_shader_out));
break;
default:
for (unsigned i = 0; i < num_vars; i++) {
_mesa_set_add(live, instr->variables[i]->var);
}
break;
}
}
static void
add_var_use_call(nir_call_instr *instr, struct set *live)
{
if (instr->return_deref != NULL) {
nir_variable *var = instr->return_deref->var;
_mesa_set_add(live, var);
}
for (unsigned i = 0; i < instr->num_params; i++) {
nir_variable *var = instr->params[i]->var;
_mesa_set_add(live, var);
}
}
static void
add_var_use_tex(nir_tex_instr *instr, struct set *live)
{
if (instr->texture != NULL) {
nir_variable *var = instr->texture->var;
_mesa_set_add(live, var);
}
if (instr->sampler != NULL) {
nir_variable *var = instr->sampler->var;
_mesa_set_add(live, var);
}
}
static void
add_var_use_shader(nir_shader *shader, struct set *live, nir_variable_mode modes)
{
nir_foreach_function(function, shader) {
if (function->impl) {
nir_foreach_block(block, function->impl) {
nir_foreach_instr(instr, block) {
switch(instr->type) {
case nir_instr_type_intrinsic:
add_var_use_intrinsic(nir_instr_as_intrinsic(instr), live,
modes);
break;
case nir_instr_type_call:
add_var_use_call(nir_instr_as_call(instr), live);
break;
case nir_instr_type_tex:
add_var_use_tex(nir_instr_as_tex(instr), live);
break;
default:
break;
}
}
}
}
}
}
static void
remove_dead_var_writes(nir_shader *shader, struct set *live)
{
nir_foreach_function(function, shader) {
if (!function->impl)
continue;
nir_foreach_block(block, function->impl) {
nir_foreach_instr_safe(instr, block) {
if (instr->type != nir_instr_type_intrinsic)
continue;
nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
if (intrin->intrinsic != nir_intrinsic_copy_var &&
intrin->intrinsic != nir_intrinsic_store_var)
continue;
/* Stores to dead variables need to be removed */
if (intrin->variables[0]->var->data.mode == 0)
nir_instr_remove(instr);
}
}
}
}
static bool
remove_dead_vars(struct exec_list *var_list, struct set *live)
{
bool progress = false;
foreach_list_typed_safe(nir_variable, var, node, var_list) {
struct set_entry *entry = _mesa_set_search(live, var);
if (entry == NULL) {
/* Mark this variable as used by setting the mode to 0 */
var->data.mode = 0;
exec_node_remove(&var->node);
progress = true;
}
}
return progress;
}
bool
nir_remove_dead_variables(nir_shader *shader, nir_variable_mode modes)
{
bool progress = false;
struct set *live =
_mesa_set_create(NULL, _mesa_hash_pointer, _mesa_key_pointer_equal);
add_var_use_shader(shader, live, modes);
if (modes & nir_var_uniform)
progress = remove_dead_vars(&shader->uniforms, live) || progress;
if (modes & nir_var_shader_in)
progress = remove_dead_vars(&shader->inputs, live) || progress;
if (modes & nir_var_shader_out)
progress = remove_dead_vars(&shader->outputs, live) || progress;
if (modes & nir_var_global)
progress = remove_dead_vars(&shader->globals, live) || progress;
if (modes & nir_var_system_value)
progress = remove_dead_vars(&shader->system_values, live) || progress;
if (modes & nir_var_shared)
progress = remove_dead_vars(&shader->shared, live) || progress;
if (modes & nir_var_local) {
nir_foreach_function(function, shader) {
if (function->impl) {
if (remove_dead_vars(&function->impl->locals, live))
progress = true;
}
}
}
if (progress) {
remove_dead_var_writes(shader, live);
nir_foreach_function(function, shader) {
if (function->impl) {
nir_metadata_preserve(function->impl, nir_metadata_block_index |
nir_metadata_dominance);
}
}
}
_mesa_set_destroy(live, NULL);
return progress;
}
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