view release on metacpan or  search on metacpan

libjit/jit/jit-reg-alloc.c  view on Meta::CPAN

/*
 * jit-reg-alloc.c - Register allocation routines for the JIT.
 *
 * Copyright (C) 2004  Southern Storm Software, Pty Ltd.
 *
 * This file is part of the libjit library.
 *
 * The libjit library is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation, either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * The libjit library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with the libjit library.  If not, see
 * <http://www.gnu.org/licenses/>.
 */

#include "jit-internal.h"
#include "jit-reg-alloc.h"
#include <jit/jit-dump.h>
#include <stdio.h>
#include <string.h>

/*@

The @code{libjit} library provides a number of functions for
performing register allocation within basic blocks so that you
mostly don't have to worry about it:

@*/

/*
 * Dump debug information about the register allocation state.
 */
#undef JIT_REG_DEBUG

/*
 * Minimum number of times a candidate must be used before it
 * is considered worthy of putting in a global register.
 */
#define	JIT_MIN_USED		3

/*
 * Use is_register_occupied() function.
 */
#undef IS_REGISTER_OCCUPIED

/*
 * Check if the register is on the register stack.
 */
#ifdef JIT_REG_STACK
#define IS_STACK_REG(reg)	((jit_reg_flags(reg) & JIT_REG_IN_STACK) != 0)
#else
#define IS_STACK_REG(reg)	(0)
#endif

/* The cost value that precludes using the register in question. */
#define COST_TOO_MUCH		1000000

#define COST_COPY		4
#define COST_SPILL_DIRTY	16
#define COST_SPILL_DIRTY_GLOBAL	4
#define COST_SPILL_CLEAN	1
#define COST_SPILL_CLEAN_GLOBAL	1
#define COST_GLOBAL_BIAS	2
#define COST_THRASH		100
#define COST_CLOBBER_GLOBAL	1000

#ifdef JIT_BACKEND_X86
# define ALLOW_CLOBBER_GLOBAL	1
#else
# define ALLOW_CLOBBER_GLOBAL	0
#endif

/* Value usage flags. */
#define VALUE_INPUT		1
#define VALUE_USED		2
#define VALUE_LIVE		4
#define VALUE_DEAD		8

/* Clobber flags. */
#define CLOBBER_NONE		0
#define CLOBBER_INPUT_VALUE	1
#define CLOBBER_REG		2
#define CLOBBER_OTHER_REG	4

#ifdef JIT_REG_DEBUG
#include <stdlib.h>

static void dump_regs(jit_gencode_t gen, const char *name)
{
	int reg, index;
	jit_value_t value;