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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 bool
deref_used_for_not_store(nir_deref_instr *deref)
{
nir_foreach_use(src, &deref->dest.ssa) {
switch (src->parent_instr->type) {
case nir_instr_type_deref:
if (deref_used_for_not_store(nir_instr_as_deref(src->parent_instr)))
return true;
break;
case nir_instr_type_intrinsic: {
nir_intrinsic_instr *intrin =
nir_instr_as_intrinsic(src->parent_instr);
/* The first source of copy and store intrinsics is the deref to
* write. Don't record those.
*/
if ((intrin->intrinsic != nir_intrinsic_store_deref &&
intrin->intrinsic != nir_intrinsic_copy_deref) ||
src != &intrin->src[0])
return true;
break;
}
default:
/* If it's used by any other instruction type (most likely a texture
* or call instruction), consider it used.
*/
return true;
}
}
return false;
}
static void
add_var_use_deref(nir_deref_instr *deref, struct set *live)
{
if (deref->deref_type != nir_deref_type_var)
return;
/* If it's not a local that never escapes the shader, then any access at
* all means we need to keep it alive.
*/
assert(deref->mode == deref->var->data.mode);
if (!(deref->mode & (nir_var_local | nir_var_global | nir_var_shared)) ||
deref_used_for_not_store(deref))
_mesa_set_add(live, deref->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) {
if (instr->type == nir_instr_type_deref)
add_var_use_deref(nir_instr_as_deref(instr), live);
}
}
}
}
}
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) {
switch (instr->type) {
case nir_instr_type_deref: {
nir_deref_instr *deref = nir_instr_as_deref(instr);
nir_variable_mode parent_mode;
if (deref->deref_type == nir_deref_type_var)
parent_mode = deref->var->data.mode;
else
parent_mode = nir_deref_instr_parent(deref)->mode;
/* If the parent mode is 0, then it references a dead variable.
* Flag this deref as dead and remove it.
*/
if (parent_mode == 0) {
deref->mode = 0;
nir_instr_remove(&deref->instr);
}
break;
}
case nir_instr_type_intrinsic: {
nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
if (intrin->intrinsic != nir_intrinsic_copy_deref &&
intrin->intrinsic != nir_intrinsic_store_deref)
break;
if (nir_src_as_deref(intrin->src[0])->mode == 0)
nir_instr_remove(instr);
break;
}
default:
break; /* Nothing to do */
}
}
}
}
}
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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