/*
* 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 pass can be compared with opt_copy_propagation, which operands
* on arbitrary whole-variable copies. However, in order to handle
* the copy propagation of swizzled variables or writemasked writes,
* we want to track things on a channel-wise basis. I found that
* trying to mix the swizzled/writemasked support here with the
* whole-variable stuff in opt_copy_propagation.cpp just made a mess,
* so this is separate despite the ACP handling being somewhat
* similar.
*
* This should reduce the number of MOV instructions in the generated
* programs unless copy propagation is also done on the LIR, and may
* help anyway by triggering other optimizations that live in the HIR.
*/
#include "ir.h"
#include "ir_rvalue_visitor.h"
#include "ir_basic_block.h"
#include "ir_optimization.h"
#include "glsl_types.h"
static bool debug = false;
namespace {
class acp_entry : public exec_node
{
public:
acp_entry(ir_variable *lhs, ir_variable *rhs, int write_mask, int swizzle[4])
{
this->lhs = lhs;
this->rhs = rhs;
this->write_mask = write_mask;
memcpy(this->swizzle, swizzle, sizeof(this->swizzle));
}
acp_entry(acp_entry *a)
{
this->lhs = a->lhs;
this->rhs = a->rhs;
this->write_mask = a->write_mask;
memcpy(this->swizzle, a->swizzle, sizeof(this->swizzle));
}
ir_variable *lhs;
ir_variable *rhs;
unsigned int write_mask;
int swizzle[4];
};
class kill_entry : public exec_node
{
public:
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->shader_mem_ctx = NULL;
this->acp = new(mem_ctx) exec_list;
this->kills = new(mem_ctx) exec_list;
}
~ir_copy_propagation_elements_visitor()
{
ralloc_free(mem_ctx);
}
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);
/** List of acp_entry: The available copies to propagate */
exec_list *acp;
/**
* 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;
/* Context for allocating new shader nodes. */
void *shader_mem_ctx;
};
} /* unnamed namespace */
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_acp = this->acp;
exec_list *orig_kills = this->kills;
bool orig_killed_all = this->killed_all;
this->acp = new(mem_ctx) exec_list;
this->kills = new(mem_ctx) exec_list;
this->killed_all = false;
visit_list_elements(this, &ir->body);
this->kills = orig_kills;
this->acp = orig_acp;
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();
if (var->type->is_scalar() || var->type->is_vector()) {
kill_entry *k;
if (lhs)
k = new(mem_ctx) kill_entry(var, ir->write_mask);
else
k = new(mem_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 *ir)
{
/* 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];
int chans;
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.
*/
foreach_iter(exec_list_iterator, iter, *this->acp) {
acp_entry *entry = (acp_entry *)iter.get();
if (var == entry->lhs) {
for (int c = 0; c < chans; c++) {
if (entry->write_mask & (1 << swizzle_chan[c])) {
source[c] = entry->rhs;
source_chan[c] = entry->swizzle[swizzle_chan[c]];
}
}
}
}
/* 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);
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);
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 */
exec_list_iterator sig_param_iter = ir->callee->parameters.iterator();
foreach_iter(exec_list_iterator, iter, ir->actual_parameters) {
ir_variable *sig_param = (ir_variable *)sig_param_iter.get();
ir_instruction *ir = (ir_instruction *)iter.get();
if (sig_param->mode != ir_var_function_out
&& sig_param->mode != ir_var_function_inout) {
ir->accept(this);
}
sig_param_iter.next();
}
/* Since we're unlinked, we don't (necessarily) know the side effects of
* this call. So kill all copies.
*/
acp->make_empty();
this->killed_all = true;
return visit_continue_with_parent;
}
void
ir_copy_propagation_elements_visitor::handle_if_block(exec_list *instructions)
{
exec_list *orig_acp = this->acp;
exec_list *orig_kills = this->kills;
bool orig_killed_all = this->killed_all;
this->acp = new(mem_ctx) exec_list;
this->kills = new(mem_ctx) exec_list;
this->killed_all = false;
/* Populate the initial acp with a copy of the original */
foreach_iter(exec_list_iterator, iter, *orig_acp) {
acp_entry *a = (acp_entry *)iter.get();
this->acp->push_tail(new(this->mem_ctx) acp_entry(a));
}
visit_list_elements(this, instructions);
if (this->killed_all) {
orig_acp->make_empty();
}
exec_list *new_kills = this->kills;
this->kills = orig_kills;
this->acp = orig_acp;
this->killed_all = this->killed_all || orig_killed_all;
/* Move the new kills into the parent block's list, removing them
* from the parent's ACP list in the process.
*/
foreach_list_safe(node, new_kills) {
kill_entry *k = (kill_entry *)node;
kill(k);
}
}
ir_visitor_status
ir_copy_propagation_elements_visitor::visit_enter(ir_if *ir)
{
ir->condition->accept(this);
handle_if_block(&ir->then_instructions);
handle_if_block(&ir->else_instructions);
/* handle_if_block() already descended into the children. */
return visit_continue_with_parent;
}
ir_visitor_status
ir_copy_propagation_elements_visitor::visit_enter(ir_loop *ir)
{
exec_list *orig_acp = this->acp;
exec_list *orig_kills = this->kills;
bool orig_killed_all = this->killed_all;
/* FINISHME: For now, the initial acp for loops is totally empty.
* We could go through once, then go through again with the acp
* cloned minus the killed entries after the first run through.
*/
this->acp = new(mem_ctx) exec_list;
this->kills = new(mem_ctx) exec_list;
this->killed_all = false;
visit_list_elements(this, &ir->body_instructions);
if (this->killed_all) {
orig_acp->make_empty();
}
exec_list *new_kills = this->kills;
this->kills = orig_kills;
this->acp = orig_acp;
this->killed_all = this->killed_all || orig_killed_all;
foreach_list_safe(node, new_kills) {
kill_entry *k = (kill_entry *)node;
kill(k);
}
/* 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)
{
foreach_list_safe(node, acp) {
acp_entry *entry = (acp_entry *)node;
if (entry->lhs == k->var) {
entry->write_mask = entry->write_mask & ~k->write_mask;
if (entry->write_mask == 0) {
entry->remove();
continue;
}
}
if (entry->rhs == k->var) {
entry->remove();
}
}
/* 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)
{
acp_entry *entry;
int orig_swizzle[4] = {0, 1, 2, 3};
int swizzle[4];
if (ir->condition)
return;
ir_dereference_variable *lhs = ir->lhs->as_dereference_variable();
if (!lhs || !(lhs->type->is_scalar() || lhs->type->is_vector()))
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;
}
/* 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);
}
}
entry = new(this->mem_ctx) acp_entry(lhs->var, rhs->var, write_mask,
swizzle);
this->acp->push_tail(entry);
}
bool
do_copy_propagation_elements(exec_list *instructions)
{
ir_copy_propagation_elements_visitor v;
visit_list_elements(&v, instructions);
return v.progress;
}