mirror of https://gitlab.freedesktop.org/mesa/mesa
219 lines
5.9 KiB
C++
219 lines
5.9 KiB
C++
/*
|
|
* 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_dead_code.cpp
|
|
*
|
|
* Eliminates dead assignments and variable declarations from the code.
|
|
*/
|
|
|
|
#define NULL 0
|
|
#include "ir.h"
|
|
#include "ir_visitor.h"
|
|
#include "ir_expression_flattening.h"
|
|
#include "glsl_types.h"
|
|
|
|
class variable_entry : public exec_node
|
|
{
|
|
public:
|
|
variable_entry(ir_variable *var)
|
|
{
|
|
this->var = var;
|
|
assign = NULL;
|
|
referenced_count = 0;
|
|
assigned_count = 0;
|
|
declaration = false;
|
|
}
|
|
|
|
ir_variable *var; /* The key: the variable's pointer. */
|
|
ir_assignment *assign; /* An assignment to the variable, if any */
|
|
|
|
/** Number of times the variable is referenced, including assignments. */
|
|
unsigned referenced_count;
|
|
|
|
/** Number of times the variable is assignmened. */
|
|
unsigned assigned_count;
|
|
|
|
bool declaration; /* If the variable had a decl in the instruction stream */
|
|
};
|
|
|
|
class ir_dead_code_visitor : public ir_hierarchical_visitor {
|
|
public:
|
|
virtual ir_visitor_status visit(ir_variable *);
|
|
virtual ir_visitor_status visit(ir_dereference_variable *);
|
|
|
|
virtual ir_visitor_status visit_enter(ir_function *);
|
|
virtual ir_visitor_status visit_leave(ir_assignment *);
|
|
|
|
variable_entry *get_variable_entry(ir_variable *var);
|
|
|
|
bool (*predicate)(ir_instruction *ir);
|
|
ir_instruction *base_ir;
|
|
|
|
/* List of variable_entry */
|
|
exec_list variable_list;
|
|
};
|
|
|
|
|
|
variable_entry *
|
|
ir_dead_code_visitor::get_variable_entry(ir_variable *var)
|
|
{
|
|
assert(var);
|
|
foreach_iter(exec_list_iterator, iter, this->variable_list) {
|
|
variable_entry *entry = (variable_entry *)iter.get();
|
|
if (entry->var == var)
|
|
return entry;
|
|
}
|
|
|
|
variable_entry *entry = new variable_entry(var);
|
|
this->variable_list.push_tail(entry);
|
|
return entry;
|
|
}
|
|
|
|
|
|
ir_visitor_status
|
|
ir_dead_code_visitor::visit(ir_variable *ir)
|
|
{
|
|
variable_entry *entry = this->get_variable_entry(ir);
|
|
if (entry)
|
|
entry->declaration = true;
|
|
|
|
return visit_continue;
|
|
}
|
|
|
|
|
|
ir_visitor_status
|
|
ir_dead_code_visitor::visit(ir_dereference_variable *ir)
|
|
{
|
|
ir_variable *const var = ir->variable_referenced();
|
|
variable_entry *entry = this->get_variable_entry(var);
|
|
|
|
if (entry)
|
|
entry->referenced_count++;
|
|
|
|
return visit_continue;
|
|
}
|
|
|
|
|
|
ir_visitor_status
|
|
ir_dead_code_visitor::visit_enter(ir_function *ir)
|
|
{
|
|
(void) ir;
|
|
return visit_continue_with_parent;
|
|
}
|
|
|
|
|
|
ir_visitor_status
|
|
ir_dead_code_visitor::visit_leave(ir_assignment *ir)
|
|
{
|
|
variable_entry *entry;
|
|
entry = this->get_variable_entry(ir->lhs->variable_referenced());
|
|
if (entry) {
|
|
entry->assigned_count++;
|
|
if (entry->assign == NULL)
|
|
entry->assign = ir;
|
|
}
|
|
|
|
return visit_continue;
|
|
}
|
|
|
|
|
|
/**
|
|
* Do a dead code pass over instructions and everything that instructions
|
|
* references.
|
|
*
|
|
* Note that this will remove assignments to globals, so it is not suitable
|
|
* for usage on an unlinked instruction stream.
|
|
*/
|
|
bool
|
|
do_dead_code(exec_list *instructions)
|
|
{
|
|
ir_dead_code_visitor v;
|
|
bool progress = false;
|
|
|
|
v.run(instructions);
|
|
|
|
foreach_iter(exec_list_iterator, iter, v.variable_list) {
|
|
variable_entry *entry = (variable_entry *)iter.get();
|
|
|
|
/* Since each assignment is a reference, the refereneced count must be
|
|
* greater than or equal to the assignment count. If they are equal,
|
|
* then all of the references are assignments, and the variable is
|
|
* dead.
|
|
*
|
|
* Note that if the variable is neither assigned nor referenced, both
|
|
* counts will be zero and will be caught by the equality test.
|
|
*/
|
|
assert(entry->referenced_count >= entry->assigned_count);
|
|
|
|
if ((entry->referenced_count > entry->assigned_count)
|
|
|| !entry->declaration)
|
|
continue;
|
|
|
|
if (entry->assign) {
|
|
/* Remove a single dead assignment to the variable we found.
|
|
* Don't do so if it's a shader output, though.
|
|
*/
|
|
if (!entry->var->shader_out) {
|
|
entry->assign->remove();
|
|
progress = true;
|
|
}
|
|
} else {
|
|
/* If there are no assignments or references to the variable left,
|
|
* then we can remove its declaration.
|
|
*/
|
|
entry->var->remove();
|
|
progress = true;
|
|
}
|
|
}
|
|
return progress;
|
|
}
|
|
|
|
/**
|
|
* Does a dead code pass on the functions present in the instruction stream.
|
|
*
|
|
* This is suitable for use while the program is not linked, as it will
|
|
* ignore variable declarations (and the assignments to them) for variables
|
|
* with global scope.
|
|
*/
|
|
bool
|
|
do_dead_code_unlinked(exec_list *instructions)
|
|
{
|
|
bool progress = false;
|
|
|
|
foreach_iter(exec_list_iterator, iter, *instructions) {
|
|
ir_instruction *ir = (ir_instruction *)iter.get();
|
|
ir_function *f = ir->as_function();
|
|
if (f) {
|
|
foreach_iter(exec_list_iterator, sigiter, *f) {
|
|
ir_function_signature *sig =
|
|
(ir_function_signature *) sigiter.get();
|
|
if (do_dead_code(&sig->body))
|
|
progress = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
return progress;
|
|
}
|