/*
* Copyright © 2010 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.
*/
/**
* \file opt_copy_propagation_elements.cpp
*
* Replaces usage of recently-copied components of variables with the
* previous copy of the variable.
*
* This should reduce the number of MOV instructions in the generated
* programs and help triggering other optimizations that live in GLSL
* level.
*/
#include "ir.h"
#include "ir_rvalue_visitor.h"
#include "ir_basic_block.h"
#include "ir_optimization.h"
#include "compiler/glsl_types.h"
#include "util/hash_table.h"
#include "util/set.h"
static bool debug = false;
namespace {
class acp_entry
{
public:
DECLARE_LINEAR_ZALLOC_CXX_OPERATORS(acp_entry)
/* If set, rhs_full indicates that this ACP entry represents a
* whole-variable copy. The rhs_element[] array will still be filled,
* to allow the swizzling from its components in case the variable
* was a vector (and to simplify some of the erase() and write_vector()
* logic).
*/
ir_variable *rhs_full;
ir_variable *rhs_element[4];
unsigned rhs_channel[4];
/* Set of variables that use the variable associated with this acp_entry as
* RHS. This has the "reverse references" of rhs_full/rhs_element. It is
* used to speed up invalidating those references when the acp_entry
* changes.
*/
set *dsts;
};
class copy_propagation_state {
public:
DECLARE_RZALLOC_CXX_OPERATORS(copy_propagation_state);
static
copy_propagation_state* create(void *mem_ctx)
{
return new (mem_ctx) copy_propagation_state(NULL);
}
copy_propagation_state* clone()
{
return new (ralloc_parent(this)) copy_propagation_state(this);
}
void erase_all()
{
/* Individual elements were allocated from a linear allocator, so will
* be destroyed when the state is destroyed.
*/
_mesa_hash_table_clear(acp, NULL);
fallback = NULL;
}
void erase(ir_variable *var, unsigned write_mask)
{
acp_entry *entry = pull_acp(var);
entry->rhs_full = NULL;
for (int i = 0; i < 4; i++) {
if (!entry->rhs_element[i])
continue;
if ((write_mask & (1 << i)) == 0)
continue;
ir_variable *to_remove = entry->rhs_element[i];
entry->rhs_element[i] = NULL;
remove_unused_var_from_dsts(entry, var, to_remove);
}
/* TODO: Check write mask, and possibly not clear everything. */
/* For any usage of our variable on the RHS, clear it out. */
set_foreach(entry->dsts, set_entry) {
ir_variable *dst_var = (ir_variable *)set_entry->key;
acp_entry *dst_entry = pull_acp(dst_var);
for (int i = 0; i < 4; i++) {
if (dst_entry->rhs_element[i] == var)
dst_entry->rhs_element[i] = NULL;
}
if (dst_entry->rhs_full == var)
dst_entry->rhs_full = NULL;
_mesa_set_remove(entry->dsts, set_entry);
}
}
acp_entry *read(ir_variable *var)
{
for (copy_propagation_state *s = this; s != NULL; s = s->fallback) {
hash_entry *ht_entry = _mesa_hash_table_search(s->acp, var);
if (ht_entry)
return (acp_entry *) ht_entry->data;
}
return NULL;
}
void write_elements(ir_variable *lhs, ir_variable *rhs, unsigned write_mask, int swizzle[4])
{
acp_entry *lhs_entry = pull_acp(lhs);
lhs_entry->rhs_full = NULL;
for (int i = 0; i < 4; i++) {
if ((write_mask & (1 << i)) == 0)
continue;
ir_variable *to_remove = lhs_entry->rhs_element[i];
lhs_entry->rhs_element[i] = rhs;
lhs_entry->rhs_channel[i] = swizzle[i];
remove_unused_var_from_dsts(lhs_entry, lhs, to_remove);
}
acp_entry *rhs_entry = pull_acp(rhs);
_mesa_set_add(rhs_entry->dsts, lhs);
}
void write_full(ir_variable *lhs, ir_variable *rhs)
{
acp_entry *lhs_entry = pull_acp(lhs);
if (lhs_entry->rhs_full == rhs)
return;
if (lhs_entry->rhs_full) {
remove_from_dsts(lhs_entry->rhs_full, lhs);
} else if (lhs->type->is_vector()) {
for (int i = 0; i < 4; i++) {
if (lhs_entry->rhs_element[i])
remove_from_dsts(lhs_entry->rhs_element[i], lhs);
}
}
lhs_entry->rhs_full = rhs;
acp_entry *rhs_entry = pull_acp(rhs);
_mesa_set_add(rhs_entry->dsts, lhs);
if (lhs->type->is_vector()) {
for (int i = 0; i < 4; i++) {
lhs_entry->rhs_element[i] = rhs;
lhs_entry->rhs_channel[i] = i;
}
}
}
void remove_unused_var_from_dsts(acp_entry *lhs_entry, ir_variable *lhs, ir_variable *var)
{
if (!var)
return;
/* If lhs still uses var, don't remove anything. */
for (int j = 0; j < 4; j++) {
if (lhs_entry->rhs_element[j] == var)
return;
}
acp_entry *element = pull_acp(var);
assert(element);
_mesa_set_remove_key(element->dsts, lhs);
}
private:
explicit copy_propagation_state(copy_propagation_state *fallback)
{
this->fallback = fallback;
/* Use 'this' as context for the table, no explicit destruction
* needed later.
*/
acp = _mesa_pointer_hash_table_create(this);
lin_ctx = linear_alloc_parent(this, 0);
}
acp_entry *pull_acp(ir_variable *var)
{
hash_entry *ht_entry = _mesa_hash_table_search(acp, var);
if (ht_entry)
return (acp_entry *) ht_entry->data;
/* If not found, create one and copy data from fallback if available. */
acp_entry *entry = new(lin_ctx) acp_entry();
_mesa_hash_table_insert(acp, var, entry);
bool found = false;
for (copy_propagation_state *s = fallback; s != NULL; s = s->fallback) {
hash_entry *fallback_ht_entry = _mesa_hash_table_search(s->acp, var);
if (fallback_ht_entry) {
acp_entry *fallback_entry = (acp_entry *) fallback_ht_entry->data;
*entry = *fallback_entry;
entry->dsts = _mesa_set_clone(fallback_entry->dsts, this);
found = true;
break;
}
}
if (!found) {
entry->dsts = _mesa_pointer_set_create(this);
}
return entry;
}
void
remove_from_dsts(ir_variable *var, ir_variable *to_remove)
{
acp_entry *entry = pull_acp(var);
assert(entry);
_mesa_set_remove_key(entry->dsts, to_remove);
}
/** Available Copy to Propagate table, from variable to the entry
* containing the current sources that can be used. */
hash_table *acp;
/** When a state is cloned, entries are copied on demand from fallback. */
copy_propagation_state *fallback;
void *lin_ctx;
};
class kill_entry : public exec_node
{
public:
/* override operator new from exec_node */
DECLARE_LINEAR_ZALLOC_CXX_OPERATORS(kill_entry)
kill_entry(ir_variable *var, int write_mask)
{
this->var = var;
this->write_mask = write_mask;
}
ir_variable *var;
unsigned int write_mask;
};
class ir_copy_propagation_elements_visitor : public ir_rvalue_visitor {
public:
ir_copy_propagation_elements_visitor()
{
this->progress = false;
this->killed_all = false;
this->mem_ctx = ralloc_context(NULL);
this->lin_ctx = linear_alloc_parent(this->mem_ctx, 0);
this->shader_mem_ctx = NULL;
this->kills = new(mem_ctx) exec_list;
this->state = copy_propagation_state::create(mem_ctx);
}
~ir_copy_propagation_elements_visitor()
{
ralloc_free(mem_ctx);
}
virtual ir_visitor_status visit(ir_dereference_variable *);
void handle_loop(ir_loop *, bool keep_acp);
virtual ir_visitor_status visit_enter(class ir_loop *);
virtual ir_visitor_status visit_enter(class ir_function_signature *);
virtual ir_visitor_status visit_leave(class ir_assignment *);
virtual ir_visitor_status visit_enter(class ir_call *);
virtual ir_visitor_status visit_enter(class ir_if *);
virtual ir_visitor_status visit_leave(class ir_swizzle *);
void handle_rvalue(ir_rvalue **rvalue);
void add_copy(ir_assignment *ir);
void kill(kill_entry *k);
void handle_if_block(exec_list *instructions, exec_list *kills, bool *killed_all);
copy_propagation_state *state;
/**
* List of kill_entry: The variables whose values were killed in this
* block.
*/
exec_list *kills;
bool progress;
bool killed_all;
/* Context for our local data structures. */
void *mem_ctx;
void *lin_ctx;
/* Context for allocating new shader nodes. */
void *shader_mem_ctx;
};
} /* unnamed namespace */
ir_visitor_status
ir_copy_propagation_elements_visitor::visit(ir_dereference_variable *ir)
{
if (this->in_assignee)
return visit_continue;
const acp_entry *entry = state->read(ir->var);
if (entry && entry->rhs_full) {
ir->var = (ir_variable *) entry->rhs_full;
progress = true;
}
return visit_continue;
}
ir_visitor_status
ir_copy_propagation_elements_visitor::visit_enter(ir_function_signature *ir)
{
/* Treat entry into a function signature as a completely separate
* block. Any instructions at global scope will be shuffled into
* main() at link time, so they're irrelevant to us.
*/
exec_list *orig_kills = this->kills;
bool orig_killed_all = this->killed_all;
this->kills = new(mem_ctx) exec_list;
this->killed_all = false;
copy_propagation_state *orig_state = state;
this->state = copy_propagation_state::create(mem_ctx);
visit_list_elements(this, &ir->body);
delete this->state;
this->state = orig_state;
ralloc_free(this->kills);
this->kills = orig_kills;
this->killed_all = orig_killed_all;
return visit_continue_with_parent;
}
ir_visitor_status
ir_copy_propagation_elements_visitor::visit_leave(ir_assignment *ir)
{
ir_dereference_variable *lhs = ir->lhs->as_dereference_variable();
ir_variable *var = ir->lhs->variable_referenced();
kill_entry *k;
if (lhs && var->type->is_vector())
k = new(this->lin_ctx) kill_entry(var, ir->write_mask);
else
k = new(this->lin_ctx) kill_entry(var, ~0);
kill(k);
add_copy(ir);
return visit_continue;
}
ir_visitor_status
ir_copy_propagation_elements_visitor::visit_leave(ir_swizzle *)
{
/* Don't visit the values of swizzles since they are handled while
* visiting the swizzle itself.
*/
return visit_continue;
}
/**
* Replaces dereferences of ACP RHS variables with ACP LHS variables.
*
* This is where the actual copy propagation occurs. Note that the
* rewriting of ir_dereference means that the ir_dereference instance
* must not be shared by multiple IR operations!
*/
void
ir_copy_propagation_elements_visitor::handle_rvalue(ir_rvalue **ir)
{
int swizzle_chan[4];
ir_dereference_variable *deref_var;
ir_variable *source[4] = {NULL, NULL, NULL, NULL};
int source_chan[4] = {0, 0, 0, 0};
int chans;
bool noop_swizzle = true;
if (!*ir)
return;
ir_swizzle *swizzle = (*ir)->as_swizzle();
if (swizzle) {
deref_var = swizzle->val->as_dereference_variable();
if (!deref_var)
return;
swizzle_chan[0] = swizzle->mask.x;
swizzle_chan[1] = swizzle->mask.y;
swizzle_chan[2] = swizzle->mask.z;
swizzle_chan[3] = swizzle->mask.w;
chans = swizzle->type->vector_elements;
} else {
deref_var = (*ir)->as_dereference_variable();
if (!deref_var)
return;
swizzle_chan[0] = 0;
swizzle_chan[1] = 1;
swizzle_chan[2] = 2;
swizzle_chan[3] = 3;
chans = deref_var->type->vector_elements;
}
if (this->in_assignee)
return;
ir_variable *var = deref_var->var;
/* Try to find ACP entries covering swizzle_chan[], hoping they're
* the same source variable.
*/
const acp_entry *entry = state->read(var);
if (entry) {
for (int c = 0; c < chans; c++) {
unsigned index = swizzle_chan[c];
ir_variable *src = entry->rhs_element[index];
if (!src)
continue;
source[c] = src;
source_chan[c] = entry->rhs_channel[index];
if (source_chan[c] != swizzle_chan[c])
noop_swizzle = false;
}
}
/* Make sure all channels are copying from the same source variable. */
if (!source[0])
return;
for (int c = 1; c < chans; c++) {
if (source[c] != source[0])
return;
}
if (!shader_mem_ctx)
shader_mem_ctx = ralloc_parent(deref_var);
/* Don't pointlessly replace the rvalue with itself (or a noop swizzle
* of itself, which would just be deleted by opt_noop_swizzle).
*/
if (source[0] == var && noop_swizzle)
return;
if (debug) {
printf("Copy propagation from:\n");
(*ir)->print();
}
deref_var = new(shader_mem_ctx) ir_dereference_variable(source[0]);
*ir = new(shader_mem_ctx) ir_swizzle(deref_var,
source_chan[0],
source_chan[1],
source_chan[2],
source_chan[3],
chans);
progress = true;
if (debug) {
printf("to:\n");
(*ir)->print();
printf("\n");
}
}
ir_visitor_status
ir_copy_propagation_elements_visitor::visit_enter(ir_call *ir)
{
/* Do copy propagation on call parameters, but skip any out params */
foreach_two_lists(formal_node, &ir->callee->parameters,
actual_node, &ir->actual_parameters) {
ir_variable *sig_param = (ir_variable *) formal_node;
ir_rvalue *ir = (ir_rvalue *) actual_node;
if (sig_param->data.mode != ir_var_function_out
&& sig_param->data.mode != ir_var_function_inout) {
ir->accept(this);
}
}
if (!ir->callee->is_intrinsic()) {
state->erase_all();
this->killed_all = true;
} else {
if (ir->return_deref) {
kill(new(this->lin_ctx) kill_entry(ir->return_deref->var, ~0));
}
foreach_two_lists(formal_node, &ir->callee->parameters,
actual_node, &ir->actual_parameters) {
ir_variable *sig_param = (ir_variable *) formal_node;
if (sig_param->data.mode == ir_var_function_out ||
sig_param->data.mode == ir_var_function_inout) {
ir_rvalue *ir = (ir_rvalue *) actual_node;
ir_variable *var = ir->variable_referenced();
kill(new(this->lin_ctx) kill_entry(var, ~0));
}
}
}
return visit_continue_with_parent;
}
void
ir_copy_propagation_elements_visitor::handle_if_block(exec_list *instructions, exec_list *kills, bool *killed_all)
{
exec_list *orig_kills = this->kills;
bool orig_killed_all = this->killed_all;
this->kills = kills;
this->killed_all = false;
/* Populate the initial acp with a copy of the original */
copy_propagation_state *orig_state = state;
this->state = orig_state->clone();
visit_list_elements(this, instructions);
delete this->state;
this->state = orig_state;
*killed_all = this->killed_all;
this->kills = orig_kills;
this->killed_all = orig_killed_all;
}
ir_visitor_status
ir_copy_propagation_elements_visitor::visit_enter(ir_if *ir)
{
ir->condition->accept(this);
exec_list *new_kills = new(mem_ctx) exec_list;
bool then_killed_all = false;
bool else_killed_all = false;
handle_if_block(&ir->then_instructions, new_kills, &then_killed_all);
handle_if_block(&ir->else_instructions, new_kills, &else_killed_all);
if (then_killed_all || else_killed_all) {
state->erase_all();
killed_all = true;
} else {
foreach_in_list_safe(kill_entry, k, new_kills)
kill(k);
}
ralloc_free(new_kills);
/* handle_if_block() already descended into the children. */
return visit_continue_with_parent;
}
void
ir_copy_propagation_elements_visitor::handle_loop(ir_loop *ir, bool keep_acp)
{
exec_list *orig_kills = this->kills;
bool orig_killed_all = this->killed_all;
this->kills = new(mem_ctx) exec_list;
this->killed_all = false;
copy_propagation_state *orig_state = state;
if (keep_acp) {
/* Populate the initial acp with a copy of the original */
this->state = orig_state->clone();
} else {
this->state = copy_propagation_state::create(mem_ctx);
}
visit_list_elements(this, &ir->body_instructions);
delete this->state;
this->state = orig_state;
if (this->killed_all)
this->state->erase_all();
exec_list *new_kills = this->kills;
this->kills = orig_kills;
this->killed_all = this->killed_all || orig_killed_all;
foreach_in_list_safe(kill_entry, k, new_kills) {
kill(k);
}
ralloc_free(new_kills);
}
ir_visitor_status
ir_copy_propagation_elements_visitor::visit_enter(ir_loop *ir)
{
handle_loop(ir, false);
handle_loop(ir, true);
/* already descended into the children. */
return visit_continue_with_parent;
}
/* Remove any entries currently in the ACP for this kill. */
void
ir_copy_propagation_elements_visitor::kill(kill_entry *k)
{
state->erase(k->var, k->write_mask);
/* If we were on a list, remove ourselves before inserting */
if (k->next)
k->remove();
this->kills->push_tail(k);
}
/**
* Adds directly-copied channels between vector variables to the available
* copy propagation list.
*/
void
ir_copy_propagation_elements_visitor::add_copy(ir_assignment *ir)
{
if (ir->condition)
return;
{
ir_variable *lhs_var = ir->whole_variable_written();
ir_dereference_variable *rhs = ir->rhs->as_dereference_variable();
if (lhs_var != NULL && rhs && rhs->var != NULL && lhs_var != rhs->var) {
if (lhs_var->data.mode == ir_var_shader_storage ||
lhs_var->data.mode == ir_var_shader_shared ||
rhs->var->data.mode == ir_var_shader_storage ||
rhs->var->data.mode == ir_var_shader_shared ||
lhs_var->data.precise != rhs->var->data.precise) {
return;
}
state->write_full(lhs_var, rhs->var);
return;
}
}
int orig_swizzle[4] = {0, 1, 2, 3};
int swizzle[4];
ir_dereference_variable *lhs = ir->lhs->as_dereference_variable();
if (!lhs || !(lhs->type->is_scalar() || lhs->type->is_vector()))
return;
if (lhs->var->data.mode == ir_var_shader_storage ||
lhs->var->data.mode == ir_var_shader_shared)
return;
ir_dereference_variable *rhs = ir->rhs->as_dereference_variable();
if (!rhs) {
ir_swizzle *swiz = ir->rhs->as_swizzle();
if (!swiz)
return;
rhs = swiz->val->as_dereference_variable();
if (!rhs)
return;
orig_swizzle[0] = swiz->mask.x;
orig_swizzle[1] = swiz->mask.y;
orig_swizzle[2] = swiz->mask.z;
orig_swizzle[3] = swiz->mask.w;
}
if (rhs->var->data.mode == ir_var_shader_storage ||
rhs->var->data.mode == ir_var_shader_shared)
return;
/* Move the swizzle channels out to the positions they match in the
* destination. We don't want to have to rewrite the swizzle[]
* array every time we clear a bit of the write_mask.
*/
int j = 0;
for (int i = 0; i < 4; i++) {
if (ir->write_mask & (1 << i))
swizzle[i] = orig_swizzle[j++];
}
int write_mask = ir->write_mask;
if (lhs->var == rhs->var) {
/* If this is a copy from the variable to itself, then we need
* to be sure not to include the updated channels from this
* instruction in the set of new source channels to be
* copy-propagated from.
*/
for (int i = 0; i < 4; i++) {
if (ir->write_mask & (1 << orig_swizzle[i]))
write_mask &= ~(1 << i);
}
}
if (lhs->var->data.precise != rhs->var->data.precise)
return;
state->write_elements(lhs->var, rhs->var, write_mask, swizzle);
}
bool
do_copy_propagation_elements(exec_list *instructions)
{
ir_copy_propagation_elements_visitor v;
visit_list_elements(&v, instructions);
return v.progress;
}