/*
* 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_array_splitting.cpp
*
* If an array is always dereferenced with a constant index, then
* split it apart into its elements, making it more amenable to other
* optimization passes.
*
* This skips uniform/varying arrays, which would need careful
* handling due to their ir->location fields tying them to the GL API
* and other shader stages.
*/
#include "ir.h"
#include "ir_visitor.h"
#include "ir_rvalue_visitor.h"
#include "glsl_types.h"
static bool debug = false;
namespace opt_array_splitting {
class variable_entry : public exec_node
{
public:
variable_entry(ir_variable *var)
{
this->var = var;
this->split = true;
this->declaration = false;
this->components = NULL;
this->mem_ctx = NULL;
if (var->type->is_array())
this->size = var->type->length;
else
this->size = var->type->matrix_columns;
}
ir_variable *var; /* The key: the variable's pointer. */
unsigned size; /* array length or matrix columns */
/** Whether this array should be split or not. */
bool split;
/* If the variable had a decl we can work with in the instruction
* stream. We can't do splitting on function arguments, which
* don't get this variable set.
*/
bool declaration;
ir_variable **components;
/** ralloc_parent(this->var) -- the shader's talloc context. */
void *mem_ctx;
};
} /* namespace */
using namespace opt_array_splitting;
/**
* This class does a walk over the tree, coming up with the set of
* variables that could be split by looking to see if they are arrays
* that are only ever constant-index dereferenced.
*/
class ir_array_reference_visitor : public ir_hierarchical_visitor {
public:
ir_array_reference_visitor(void)
{
this->mem_ctx = ralloc_context(NULL);
this->variable_list.make_empty();
}
~ir_array_reference_visitor(void)
{
ralloc_free(mem_ctx);
}
bool get_split_list(exec_list *instructions, bool linked);
virtual ir_visitor_status visit(ir_variable *);
virtual ir_visitor_status visit(ir_dereference_variable *);
virtual ir_visitor_status visit_enter(ir_dereference_array *);
virtual ir_visitor_status visit_enter(ir_function_signature *);
variable_entry *get_variable_entry(ir_variable *var);
/* List of variable_entry */
exec_list variable_list;
void *mem_ctx;
};
variable_entry *
ir_array_reference_visitor::get_variable_entry(ir_variable *var)
{
assert(var);
if (var->mode != ir_var_auto &&
var->mode != ir_var_temporary)
return NULL;
if (!(var->type->is_array() || var->type->is_matrix()))
return NULL;
/* If the array hasn't been sized yet, we can't split it. After
* linking, this should be resolved.
*/
if (var->type->is_array() && var->type->length == 0)
return NULL;
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(mem_ctx) variable_entry(var);
this->variable_list.push_tail(entry);
return entry;
}
ir_visitor_status
ir_array_reference_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_array_reference_visitor::visit(ir_dereference_variable *ir)
{
variable_entry *entry = this->get_variable_entry(ir->var);
/* If we made it to here without seeing an ir_dereference_array,
* then the dereference of this array didn't have a constant index
* (see the visit_continue_with_parent below), so we can't split
* the variable.
*/
if (entry)
entry->split = false;
return visit_continue;
}
ir_visitor_status
ir_array_reference_visitor::visit_enter(ir_dereference_array *ir)
{
ir_dereference_variable *deref = ir->array->as_dereference_variable();
if (!deref)
return visit_continue;
variable_entry *entry = this->get_variable_entry(deref->var);
/* If the access to the array has a variable index, we wouldn't
* know which split variable this dereference should go to.
*/
if (entry && !ir->array_index->as_constant())
entry->split = false;
return visit_continue_with_parent;
}
ir_visitor_status
ir_array_reference_visitor::visit_enter(ir_function_signature *ir)
{
/* We don't have logic for array-splitting function arguments,
* so just look at the body instructions and not the parameter
* declarations.
*/
visit_list_elements(this, &ir->body);
return visit_continue_with_parent;
}
bool
ir_array_reference_visitor::get_split_list(exec_list *instructions,
bool linked)
{
visit_list_elements(this, instructions);
/* If the shaders aren't linked yet, we can't mess with global
* declarations, which need to be matched by name across shaders.
*/
if (!linked) {
foreach_list(node, instructions) {
ir_variable *var = ((ir_instruction *)node)->as_variable();
if (var) {
variable_entry *entry = get_variable_entry(var);
if (entry)
entry->remove();
}
}
}
/* Trim out variables we found that we can't split. */
foreach_iter(exec_list_iterator, iter, variable_list) {
variable_entry *entry = (variable_entry *)iter.get();
if (debug) {
printf("array %s@%p: decl %d, split %d\n",
entry->var->name, (void *) entry->var, entry->declaration,
entry->split);
}
if (!(entry->declaration && entry->split)) {
entry->remove();
}
}
return !variable_list.is_empty();
}
/**
* This class rewrites the dereferences of arrays that have been split
* to use the newly created ir_variables for each component.
*/
class ir_array_splitting_visitor : public ir_rvalue_visitor {
public:
ir_array_splitting_visitor(exec_list *vars)
{
this->variable_list = vars;
}
virtual ~ir_array_splitting_visitor()
{
}
virtual ir_visitor_status visit_leave(ir_assignment *);
void split_deref(ir_dereference **deref);
void handle_rvalue(ir_rvalue **rvalue);
variable_entry *get_splitting_entry(ir_variable *var);
exec_list *variable_list;
};
variable_entry *
ir_array_splitting_visitor::get_splitting_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;
}
}
return NULL;
}
void
ir_array_splitting_visitor::split_deref(ir_dereference **deref)
{
ir_dereference_array *deref_array = (*deref)->as_dereference_array();
if (!deref_array)
return;
ir_dereference_variable *deref_var = deref_array->array->as_dereference_variable();
if (!deref_var)
return;
ir_variable *var = deref_var->var;
variable_entry *entry = get_splitting_entry(var);
if (!entry)
return;
ir_constant *constant = deref_array->array_index->as_constant();
assert(constant);
if (constant->value.i[0] < (int)entry->size) {
*deref = new(entry->mem_ctx)
ir_dereference_variable(entry->components[constant->value.i[0]]);
} else {
/* There was a constant array access beyond the end of the
* array. This might have happened due to constant folding
* after the initial parse. This produces an undefined value,
* but shouldn't crash. Just give them an uninitialized
* variable.
*/
ir_variable *temp = new(entry->mem_ctx) ir_variable(deref_array->type,
"undef",
ir_var_temporary);
entry->components[0]->insert_before(temp);
*deref = new(entry->mem_ctx) ir_dereference_variable(temp);
}
}
void
ir_array_splitting_visitor::handle_rvalue(ir_rvalue **rvalue)
{
if (!*rvalue)
return;
ir_dereference *deref = (*rvalue)->as_dereference();
if (!deref)
return;
split_deref(&deref);
*rvalue = deref;
}
ir_visitor_status
ir_array_splitting_visitor::visit_leave(ir_assignment *ir)
{
/* The normal rvalue visitor skips the LHS of assignments, but we
* need to process those just the same.
*/
ir_rvalue *lhs = ir->lhs;
handle_rvalue(&lhs);
ir->lhs = lhs->as_dereference();
ir->lhs->accept(this);
handle_rvalue(&ir->rhs);
ir->rhs->accept(this);
if (ir->condition) {
handle_rvalue(&ir->condition);
ir->condition->accept(this);
}
return visit_continue;
}
bool
optimize_split_arrays(exec_list *instructions, bool linked)
{
ir_array_reference_visitor refs;
if (!refs.get_split_list(instructions, linked))
return false;
void *mem_ctx = ralloc_context(NULL);
/* Replace the decls of the arrays to be split with their split
* components.
*/
foreach_iter(exec_list_iterator, iter, refs.variable_list) {
variable_entry *entry = (variable_entry *)iter.get();
const struct glsl_type *type = entry->var->type;
const struct glsl_type *subtype;
if (type->is_matrix())
subtype = type->column_type();
else
subtype = type->fields.array;
entry->mem_ctx = ralloc_parent(entry->var);
entry->components = ralloc_array(mem_ctx,
ir_variable *,
entry->size);
for (unsigned int i = 0; i < entry->size; i++) {
const char *name = ralloc_asprintf(mem_ctx, "%s_%d",
entry->var->name, i);
entry->components[i] =
new(entry->mem_ctx) ir_variable(subtype, name, ir_var_temporary);
entry->var->insert_before(entry->components[i]);
}
entry->var->remove();
}
ir_array_splitting_visitor split(&refs.variable_list);
visit_list_elements(&split, instructions);
if (debug)
_mesa_print_ir(instructions, NULL);
ralloc_free(mem_ctx);
return true;
}