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/*
* 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 ir_variable_refcount.cpp
*
* Provides a visitor which produces a list of variables referenced,
* how many times they were referenced and assigned, and whether they
* were defined in the scope.
*/
#include "ir.h"
#include "ir_visitor.h"
#include "ir_variable_refcount.h"
#include "compiler/glsl_types.h"
#include "util/hash_table.h"
ir_variable_refcount_visitor::ir_variable_refcount_visitor()
{
this->mem_ctx = ralloc_context(NULL);
this->ht = _mesa_pointer_hash_table_create(NULL);
}
static void
free_entry(struct hash_entry *entry)
{
ir_variable_refcount_entry *ivre = (ir_variable_refcount_entry *) entry->data;
/* Free assignment list */
exec_node *n;
while ((n = ivre->assign_list.pop_head()) != NULL) {
struct assignment_entry *assignment_entry =
exec_node_data(struct assignment_entry, n, link);
free(assignment_entry);
}
delete ivre;
}
ir_variable_refcount_visitor::~ir_variable_refcount_visitor()
{
ralloc_free(this->mem_ctx);
_mesa_hash_table_destroy(this->ht, free_entry);
}
// constructor
ir_variable_refcount_entry::ir_variable_refcount_entry(ir_variable *var)
{
this->var = var;
assigned_count = 0;
declaration = false;
referenced_count = 0;
}
ir_variable_refcount_entry *
ir_variable_refcount_visitor::get_variable_entry(ir_variable *var)
{
assert(var);
struct hash_entry *e = _mesa_hash_table_search(this->ht, var);
if (e)
return (ir_variable_refcount_entry *)e->data;
ir_variable_refcount_entry *entry = new ir_variable_refcount_entry(var);
assert(entry->referenced_count == 0);
_mesa_hash_table_insert(this->ht, var, entry);
return entry;
}
ir_visitor_status
ir_variable_refcount_visitor::visit(ir_variable *ir)
{
ir_variable_refcount_entry *entry = this->get_variable_entry(ir);
if (entry)
entry->declaration = true;
return visit_continue;
}
ir_visitor_status
ir_variable_refcount_visitor::visit(ir_dereference_variable *ir)
{
ir_variable *const var = ir->variable_referenced();
ir_variable_refcount_entry *entry = this->get_variable_entry(var);
if (entry)
entry->referenced_count++;
return visit_continue;
}
ir_visitor_status
ir_variable_refcount_visitor::visit_enter(ir_function_signature *ir)
{
/* We don't want to descend into the function parameters and
* dead-code eliminate them, so just accept the body here.
*/
visit_list_elements(this, &ir->body);
return visit_continue_with_parent;
}
ir_visitor_status
ir_variable_refcount_visitor::visit_leave(ir_assignment *ir)
{
ir_variable_refcount_entry *entry;
entry = this->get_variable_entry(ir->lhs->variable_referenced());
if (entry) {
entry->assigned_count++;
/* Build a list for dead code optimisation. Don't add assignment if it
* was declared out of scope (outside the instruction stream). Also don't
* bother adding any more to the list if there are more references than
* assignments as this means the variable is used and won't be optimised
* out.
*/
assert(entry->referenced_count >= entry->assigned_count);
if (entry->referenced_count == entry->assigned_count) {
struct assignment_entry *assignment_entry =
(struct assignment_entry *)calloc(1, sizeof(*assignment_entry));
assignment_entry->assign = ir;
entry->assign_list.push_head(&assignment_entry->link);
}
}
return visit_continue;
}