/* -*- 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.
*/
#pragma once
#ifndef LOOP_ANALYSIS_H
#define LOOP_ANALYSIS_H
#include "ir.h"
#include "program/hash_table.h"
/**
* Analyze and classify all variables used in all loops in the instruction list
*/
extern class loop_state *
analyze_loop_variables(exec_list *instructions);
/**
* Fill in loop control fields
*
* Based on analysis of loop variables, this function tries to remove
* redundant sequences in the loop of the form
*
* (if (expression bool ...) (break))
*
* For example, if it is provable that one loop exit condition will
* always be satisfied before another, the unnecessary exit condition will be
* removed.
*/
extern bool
set_loop_controls(exec_list *instructions, loop_state *ls);
extern bool
unroll_loops(exec_list *instructions, loop_state *ls,
const struct gl_shader_compiler_options *options);
ir_rvalue *
find_initial_value(ir_loop *loop, ir_variable *var);
int
calculate_iterations(ir_rvalue *from, ir_rvalue *to, ir_rvalue *increment,
enum ir_expression_operation op);
/**
* Tracking for all variables used in a loop
*/
class loop_variable_state : public exec_node {
public:
class loop_variable *get(const ir_variable *);
class loop_variable *insert(ir_variable *);
class loop_variable *get_or_insert(ir_variable *, bool in_assignee);
class loop_terminator *insert(ir_if *);
/**
* Variables that have not yet been classified
*/
exec_list variables;
/**
* Variables whose values are constant within the body of the loop
*
* This list contains \c loop_variable objects.
*/
exec_list constants;
/**
* Induction variables for this loop
*
* This list contains \c loop_variable objects.
*/
exec_list induction_variables;
/**
* Simple if-statements that lead to the termination of the loop
*
* This list contains \c loop_terminator objects.
*
* \sa is_loop_terminator
*/
exec_list terminators;
/**
* If any of the terminators in \c terminators leads to termination of the
* loop after a constant number of iterations, this is the terminator that
* leads to termination after the smallest number of iterations. Otherwise
* NULL.
*/
loop_terminator *limiting_terminator;
/**
* Hash table containing all variables accessed in this loop
*/
hash_table *var_hash;
/**
* Number of ir_loop_jump instructions that operate on this loop
*/
unsigned num_loop_jumps;
/**
* Whether this loop contains any function calls.
*/
bool contains_calls;
loop_variable_state()
{
this->num_loop_jumps = 0;
this->contains_calls = false;
this->var_hash = hash_table_ctor(0, hash_table_pointer_hash,
hash_table_pointer_compare);
this->limiting_terminator = NULL;
}
~loop_variable_state()
{
hash_table_dtor(this->var_hash);
}
DECLARE_RALLOC_CXX_OPERATORS(loop_variable_state)
};
class loop_variable : public exec_node {
public:
/** The variable in question. */
ir_variable *var;
/** Is the variable read in the loop before it is written? */
bool read_before_write;
/** Are all variables in the RHS of the assignment loop constants? */
bool rhs_clean;
/**
* Is there an assignment to the variable that is conditional, or inside a
* nested loop?
*/
bool conditional_or_nested_assignment;
/** Reference to the first assignment to the variable in the loop body. */
ir_assignment *first_assignment;
/** Number of assignments to the variable in the loop body. */
unsigned num_assignments;
/**
* Increment value for a loop induction variable
*
* If this is a loop induction variable, the amount by which the variable
* is incremented on each iteration through the loop.
*
* If this is not a loop induction variable, NULL.
*/
ir_rvalue *increment;
inline bool is_induction_var() const
{
/* Induction variables always have a non-null increment, and vice
* versa.
*/
return this->increment != NULL;
}
inline bool is_loop_constant() const
{
const bool is_const = (this->num_assignments == 0)
|| (((this->num_assignments == 1)
&& !this->conditional_or_nested_assignment
&& !this->read_before_write
&& this->rhs_clean) || this->var->data.read_only);
/* If the RHS of *the* assignment is clean, then there must be exactly
* one assignment of the variable.
*/
assert((this->rhs_clean && (this->num_assignments == 1))
|| !this->rhs_clean);
return is_const;
}
void record_reference(bool in_assignee,
bool in_conditional_code_or_nested_loop,
ir_assignment *current_assignment);
};
class loop_terminator : public exec_node {
public:
loop_terminator()
: ir(NULL), iterations(-1)
{
}
/**
* Statement which terminates the loop.
*/
ir_if *ir;
/**
* The number of iterations after which the terminator is known to
* terminate the loop (if that is a fixed value). Otherwise -1.
*/
int iterations;
};
class loop_state {
public:
~loop_state();
/**
* Get the loop variable state data for a particular loop
*/
loop_variable_state *get(const ir_loop *);
loop_variable_state *insert(ir_loop *ir);
bool loop_found;
private:
loop_state();
/**
* Hash table containing all loops that have been analyzed.
*/
hash_table *ht;
void *mem_ctx;
friend loop_state *analyze_loop_variables(exec_list *instructions);
};
#endif /* LOOP_ANALYSIS_H */