irmode.c

/*
 * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
 *
 * This file is part of libFirm.
 *
 * This file may be distributed and/or modified under the terms of the
 * GNU General Public License version 2 as published by the Free Software
 * Foundation and appearing in the file LICENSE.GPL included in the
 * packaging of this file.
 *
 * Licensees holding valid libFirm Professional Edition licenses may use
 * this file in accordance with the libFirm Commercial License.
 * Agreement provided with the Software.
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE.
 */

/**
 * @file
 * @brief    Data modes of operations.
 * @author   Martin Trapp, Christian Schaefer, Goetz Lindenmaier, Mathias Heil
 * @version  $Id$
 */
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#ifdef HAVE_STDLIB_H
# include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
# include <string.h>
#endif

# include <stddef.h>

# include "irprog_t.h"
# include "irmode_t.h"
# include "ident.h"
# include "tv_t.h"
# include "obst.h"
# include "irhooks.h"
# include "irtools.h"
# include "array.h"

/** Obstack to hold all modes. */
static struct obstack modes;

/** Number of defined modes. */
static int num_modes = 0;

/** The list of all currently existing modes. */
static ir_mode **mode_list;

/**
 * Compare modes that don't need to have their code field
 * correctly set
 *
 * TODO: Add other fields
 **/
static INLINE int modes_are_equal(const ir_mode *m, const ir_mode *n) {
	if (m == n) return 1;
	if (m->sort         == n->sort &&
		m->arithmetic   == n->arithmetic &&
		m->size         == n->size &&
		m->sign         == n->sign  &&
		m->modulo_shift == n->modulo_shift &&
		m->vector_elem  == n->vector_elem)
		return 1;

	return 0;
}

/**
 * searches the modes obstack for the given mode and returns
 * a pointer on an equal mode already in the array, NULL if
 * none found
 */
static ir_mode *find_mode(const ir_mode *m) {
	int i;
	for (i = ARR_LEN(mode_list) - 1; i >= 0; --i) {
		ir_mode *n = mode_list[i];
		if (modes_are_equal(n, m))
			return n;
	}
	return NULL;
}

#ifdef FIRM_STATISTICS
/* return the mode index, only needed for statistics */
int stat_find_mode_index(const ir_mode *m) {
	int i;
	for (i = ARR_LEN(mode_list) - 1; i >= 0; --i) {
		ir_mode *n = mode_list[i];
		if (modes_are_equal(n, m))
			return i;
	}
	return -1;
}

/* return the mode for a given index, only needed for statistics */
ir_mode *stat_mode_for_index(int idx) {
	if (0 <= idx  && idx < ARR_LEN(mode_list))
		return mode_list[idx];
	return NULL;
}
#endif

/**
 * sets special values of modes
 */
static void set_mode_values(ir_mode* mode) {
	switch (get_mode_sort(mode))    {
	case irms_reference:
	case irms_int_number:
	case irms_float_number:
		mode->min  = get_tarval_min(mode);
		mode->max  = get_tarval_max(mode);
		mode->null = get_tarval_null(mode);
		mode->one  = get_tarval_one(mode);
		mode->minus_one = get_tarval_minus_one(mode);
		if(get_mode_sort(mode) != irms_float_number) {
			mode->all_one = get_tarval_all_one(mode);
		} else {
			mode->all_one = tarval_bad;
		}
		break;

	case irms_internal_boolean:
		mode->min  = tarval_b_false;
		mode->max  = tarval_b_true;
		mode->null = tarval_b_false;
		mode->one  = tarval_b_true;
		mode->minus_one = tarval_bad;
		mode->all_one = tarval_b_true;
		break;

	case irms_auxiliary:
	case irms_memory:
	case irms_control_flow:
		mode->min  = tarval_bad;
		mode->max  = tarval_bad;
		mode->null = tarval_bad;
		mode->one  = tarval_bad;
		mode->minus_one = tarval_bad;
		break;
	}
}

/* * *
 * globals defined in irmode.h
 * * */

/* --- Predefined modes --- */

/* FIRM internal modes: */
ir_mode *mode_T;
ir_mode *mode_X;
ir_mode *mode_M;
ir_mode *mode_BB;
ir_mode *mode_ANY;
ir_mode *mode_BAD;

/* predefined numerical modes: */
ir_mode *mode_F;    /* float */
ir_mode *mode_D;    /* double */
ir_mode *mode_E;    /* long double */

ir_mode *mode_Bs;   /* integral values, signed and unsigned */
ir_mode *mode_Bu;   /* 8 bit */
ir_mode *mode_Hs;   /* 16 bit */
ir_mode *mode_Hu;
ir_mode *mode_Is;   /* 32 bit */
ir_mode *mode_Iu;
ir_mode *mode_Ls;   /* 64 bit */
ir_mode *mode_Lu;
ir_mode *mode_LLs;  /* 128 bit */
ir_mode *mode_LLu;

ir_mode *mode_b;
ir_mode *mode_P;

/* machine specific modes */
ir_mode *mode_P_code;   /**< machine specific pointer mode for code addresses */
ir_mode *mode_P_data;   /**< machine specific pointer mode for data addresses */

/* * *
 * functions defined in irmode.h
 * * */

/* JNI access functions */
ir_mode *get_modeT(void) { return mode_T; }
ir_mode *get_modeF(void) { return mode_F; }
ir_mode *get_modeD(void) { return mode_D; }
ir_mode *get_modeE(void) { return mode_E; }
ir_mode *get_modeBs(void) { return mode_Bs; }
ir_mode *get_modeBu(void) { return mode_Bu; }
ir_mode *get_modeHs(void) { return mode_Hs; }
ir_mode *get_modeHu(void) { return mode_Hu; }
ir_mode *get_modeIs(void) { return mode_Is; }
ir_mode *get_modeIu(void) { return mode_Iu; }
ir_mode *get_modeLs(void) { return mode_Ls; }
ir_mode *get_modeLu(void) { return mode_Lu; }
ir_mode *get_modeLLs(void){ return mode_LLs; }
ir_mode *get_modeLLu(void){ return mode_LLu; }
ir_mode *get_modeb(void) { return mode_b; }
ir_mode *get_modeP(void) { return mode_P; }
ir_mode *get_modeX(void) { return mode_X; }
ir_mode *get_modeM(void) { return mode_M; }
ir_mode *get_modeBB(void) { return mode_BB; }
ir_mode *get_modeANY(void) { return mode_ANY; }
ir_mode *get_modeBAD(void) { return mode_BAD; }


ir_mode *(get_modeP_code)(void) {
	return _get_modeP_code();
}

ir_mode *(get_modeP_data)(void) {
	return _get_modeP_data();
}

void set_modeP_code(ir_mode *p) {
	assert(mode_is_reference(p));
	mode_P_code = p;
}

void set_modeP_data(ir_mode *p) {
	assert(mode_is_reference(p));
	mode_P_data = p;
}

/**
 * Registers a new mode.
 *
 * @param new_mode  The new mode template.
 */
static ir_mode *register_mode(const ir_mode *new_mode) {
	ir_mode *mode = NULL;

	assert(new_mode);

	/* copy mode struct to modes array */
	mode = (ir_mode *)obstack_copy(&modes, new_mode, sizeof(*mode));
	ARR_APP1(ir_mode*, mode_list, mode);

	mode->kind = k_ir_mode;
	if (num_modes >= irm_max)  {
		mode->code = num_modes;
	}
	num_modes++;

	/* add the new mode to the irp list of modes */
	add_irp_mode(mode);

	set_mode_values(mode);

	hook_new_mode(new_mode, mode);
	return mode;
}

/*
 * Creates a new mode.
 */
ir_mode *new_ir_mode(const char *name, mode_sort sort, int bit_size, int sign,
                     mode_arithmetic arithmetic, unsigned int modulo_shift)
{
	ir_mode mode_tmpl;
	ir_mode *mode = NULL;

	mode_tmpl.name         = new_id_from_str(name);
	mode_tmpl.sort         = sort;
	mode_tmpl.size         = bit_size;
	mode_tmpl.sign         = sign ? 1 : 0;
	mode_tmpl.modulo_shift = (mode_tmpl.sort == irms_int_number) ? modulo_shift : 0;
	mode_tmpl.vector_elem  = 1;
	mode_tmpl.arithmetic   = arithmetic;
	mode_tmpl.link         = NULL;
	mode_tmpl.tv_priv      = NULL;

	mode = find_mode(&mode_tmpl);
	if (mode) {
		hook_new_mode(&mode_tmpl, mode);
		return mode;
	}

	/* sanity checks */
	switch (sort) {
	case irms_auxiliary:
	case irms_control_flow:
	case irms_memory:
	case irms_internal_boolean:
		assert(0 && "internal modes cannot be user defined");
		break;

	case irms_float_number:
	case irms_int_number:
	case irms_reference:
		mode = register_mode(&mode_tmpl);
	}
	return mode;
}

/*
 * Creates a new vector mode.
 */
ir_mode *new_ir_vector_mode(const char *name, mode_sort sort, int bit_size, unsigned num_of_elem, int sign,
                            mode_arithmetic arithmetic, unsigned int modulo_shift)
{
	ir_mode mode_tmpl;
	ir_mode *mode = NULL;

	mode_tmpl.name         = new_id_from_str(name);
	mode_tmpl.sort         = sort;
	mode_tmpl.size         = bit_size * num_of_elem;
	mode_tmpl.sign         = sign ? 1 : 0;
	mode_tmpl.modulo_shift = (mode_tmpl.sort == irms_int_number) ? modulo_shift : 0;
	mode_tmpl.vector_elem  = num_of_elem;
	mode_tmpl.arithmetic   = arithmetic;
	mode_tmpl.link         = NULL;
	mode_tmpl.tv_priv      = NULL;

	mode = find_mode(&mode_tmpl);
	if (mode) {
		hook_new_mode(&mode_tmpl, mode);
		return mode;
	}

	if (num_of_elem <= 1) {
		assert(0 && "vector modes should have at least 2 elements");
		return NULL;
	}

	/* sanity checks */
	switch (sort) {
	case irms_auxiliary:
	case irms_control_flow:
	case irms_memory:
	case irms_internal_boolean:
		assert(0 && "internal modes cannot be user defined");
		break;

	case irms_reference:
		assert(0 && "only integer and floating point modes can be vectorized");
		break;

	case irms_float_number:
		assert(0 && "not yet implemented");
		break;

	case irms_int_number:
		mode = register_mode(&mode_tmpl);
	}
	return mode;
}

/* Functions for the direct access to all attributes of an ir_mode */
modecode (get_mode_modecode)(const ir_mode *mode) {
	return _get_mode_modecode(mode);
}

ident *(get_mode_ident)(const ir_mode *mode) {
	return _get_mode_ident(mode);
}

const char *get_mode_name(const ir_mode *mode) {
	return get_id_str(mode->name);
}

mode_sort (get_mode_sort)(const ir_mode* mode) {
	return _get_mode_sort(mode);
}

unsigned (get_mode_size_bits)(const ir_mode *mode) {
	return _get_mode_size_bits(mode);
}

unsigned (get_mode_size_bytes)(const ir_mode *mode) {
	return _get_mode_size_bytes(mode);
}

int (get_mode_sign)(const ir_mode *mode) {
	return _get_mode_sign(mode);
}

mode_arithmetic (get_mode_arithmetic)(const ir_mode *mode) {
	return get_mode_arithmetic(mode);
}


/* Attribute modulo shift specifies for modes of kind irms_int_number
 *  whether shift applies modulo to value of bits to shift.  Asserts
 *  if mode is not irms_int_number.
 */
unsigned int (get_mode_modulo_shift)(const ir_mode *mode) {
	return _get_mode_modulo_shift(mode);
}

unsigned int (get_mode_n_vector_elems)(const ir_mode *mode) {
	return _get_mode_vector_elems(mode);
}

void *(get_mode_link)(const ir_mode *mode) {
	return _get_mode_link(mode);
}

void (set_mode_link)(ir_mode *mode, void *l) {
	_set_mode_link(mode, l);
}

tarval *get_mode_min(ir_mode *mode) {
	assert(mode);
	assert(get_mode_modecode(mode) < (modecode) num_modes);
	assert(mode_is_data(mode));

	return mode->min;
}

tarval *get_mode_max(ir_mode *mode) {
	assert(mode);
	assert(get_mode_modecode(mode) < (modecode) num_modes);
	assert(mode_is_data(mode));

	return mode->max;
}

tarval *get_mode_null(ir_mode *mode) {
	assert(mode);
	assert(get_mode_modecode(mode) < (modecode) num_modes);
	assert(mode_is_datab(mode));

	return mode->null;
}

tarval *get_mode_one(ir_mode *mode) {
	assert(mode);
	assert(get_mode_modecode(mode) < (modecode) num_modes);
	assert(mode_is_datab(mode));

	return mode->one;
}

tarval *get_mode_minus_one(ir_mode *mode) {
	assert(mode);
	assert(get_mode_modecode(mode) < (modecode) num_modes);
	assert(mode_is_data(mode));

	return mode->minus_one;
}

tarval *get_mode_all_one(ir_mode *mode) {
	assert(mode);
	assert(get_mode_modecode(mode) < (modecode) num_modes);
	assert(mode_is_datab(mode));
	return mode->all_one;
}

tarval *get_mode_infinite(ir_mode *mode) {
	assert(mode);
	assert(get_mode_modecode(mode) < (modecode) num_modes);
	assert(mode_is_float(mode));

	return get_tarval_plus_inf(mode);
}

tarval *get_mode_NAN(ir_mode *mode) {
	assert(mode);
	assert(get_mode_modecode(mode) < (modecode) num_modes);
	assert(mode_is_float(mode));

	return get_tarval_nan(mode);
}

int is_mode(void *thing) {
	if (get_kind(thing) == k_ir_mode)
		return 1;
	else
		return 0;
}

int (mode_is_signed)(const ir_mode *mode) {
	return _mode_is_signed(mode);
}

int (mode_is_float)(const ir_mode *mode) {
	return _mode_is_float(mode);
}

int (mode_is_int)(const ir_mode *mode) {
	return _mode_is_int(mode);
}

int (mode_is_reference)(const ir_mode *mode) {
	return _mode_is_reference(mode);
}

int (mode_is_num)(const ir_mode *mode) {
	return _mode_is_num(mode);
}

int (mode_is_data)(const ir_mode *mode) {
	return _mode_is_data(mode);
}

int (mode_is_datab)(const ir_mode *mode) {
	return _mode_is_datab(mode);
}

int (mode_is_dataM)(const ir_mode *mode) {
	return _mode_is_dataM(mode);
}

int (mode_is_float_vector)(const ir_mode *mode) {
	return _mode_is_float_vector(mode);
}

int (mode_is_int_vector)(const ir_mode *mode) {
	return _mode_is_int_vector(mode);
}

/* Returns true if sm can be converted to lm without loss. */
int smaller_mode(const ir_mode *sm, const ir_mode *lm) {
	int sm_bits, lm_bits;

	assert(sm);
	assert(lm);

	if (sm == lm) return 1;

	sm_bits = get_mode_size_bits(sm);
	lm_bits = get_mode_size_bits(lm);

	switch (get_mode_sort(sm)) {
	case irms_int_number:
		switch (get_mode_sort(lm)) {
		case irms_int_number:
			if(get_mode_arithmetic(sm) != get_mode_arithmetic(lm))
				return 0;

			/* only two complement implemented */
			assert(get_mode_arithmetic(sm)==irma_twos_complement);

			/* integers are convertable if
			 *   - both have the same sign and lm is the larger one
			 *   - lm is the signed one and is at least two bits larger
			 *     (one for the sign, one for the highest bit of sm)
			 *   - sm & lm are two_complement and lm has greater or equal number of bits
			 */
			if(mode_is_signed(sm)) {
				if(!mode_is_signed(lm))
					return 0;
				return sm_bits <= lm_bits;
			} else {
				if(mode_is_signed(lm)) {
					return sm_bits < lm_bits;
				}
				return sm_bits <= lm_bits;
			}
			break;

		case irms_float_number:
			/* int to float works if the float is large enough */
			return 0;

		default:
			break;
		}
		break;

	case irms_float_number:
		if (get_mode_arithmetic(sm) == get_mode_arithmetic(lm)) {
			if ( (get_mode_sort(lm) == irms_float_number)
				&& (get_mode_size_bits(lm) >= get_mode_size_bits(sm)) )
				return 1;
		}
		break;

	case irms_reference:
		/* do exist machines out there with different pointer lenghts ?*/
		return 0;

	case irms_internal_boolean:
		return mode_is_int(lm);

	default:
		break;
	}

	/* else */
	return 0;
}

/* Return the signed integer equivalent mode for an reference mode. */
ir_mode *get_reference_mode_signed_eq(ir_mode *mode) {
	assert(mode_is_reference(mode));
	return mode->eq_signed;
}

/* Sets the signed integer equivalent mode for an reference mode. */
void set_reference_mode_signed_eq(ir_mode *ref_mode, ir_mode *int_mode) {
	assert(mode_is_reference(ref_mode));
	assert(mode_is_int(int_mode));
	ref_mode->eq_signed = int_mode;
}

/* Return the unsigned integer equivalent mode for an reference mode. */
ir_mode *get_reference_mode_unsigned_eq(ir_mode *mode) {
	assert(mode_is_reference(mode));
	return mode->eq_unsigned;
}

/* Sets the unsigned integer equivalent mode for an reference mode. */
void set_reference_mode_unsigned_eq(ir_mode *ref_mode, ir_mode *int_mode) {
	assert(mode_is_reference(ref_mode));
	assert(mode_is_int(int_mode));
	ref_mode->eq_unsigned = int_mode;
}

/* initialization, build the default modes */
void init_mode(void) {
	ir_mode newmode;

	obstack_init(&modes);
	mode_list = NEW_ARR_F(ir_mode*, 0);

	num_modes  =  0;
	/* initialize predefined modes */

	/* Internal Modes */
	newmode.arithmetic   = irma_none;
	newmode.size         = 0;
	newmode.sign         = 0;
	newmode.modulo_shift = 0;
	newmode.vector_elem  = 0;
	newmode.eq_signed    = NULL;
	newmode.eq_unsigned  = NULL;
	newmode.link         = NULL;
	newmode.tv_priv      = NULL;

	/* Control Flow Modes*/
	newmode.sort    = irms_control_flow;

	/* Basic Block */
	newmode.name    = new_id_from_chars("BB", 2);
	newmode.code    = irm_BB;

	mode_BB = register_mode(&newmode);

	/* eXecution */
	newmode.name    = new_id_from_chars("X", 1);
	newmode.code    = irm_X;

	mode_X = register_mode(&newmode);

	/* Memory Modes */
	newmode.sort    = irms_memory;

	/* Memory */
	newmode.name    = new_id_from_chars("M", 1);
	newmode.code    = irm_M;

	mode_M = register_mode(&newmode);

	/* Auxiliary Modes */
	newmode.sort    = irms_auxiliary,

	/* Tuple */
	newmode.name    = new_id_from_chars("T", 1);
	newmode.code    = irm_T;

	mode_T = register_mode(&newmode);

	/* ANY */
	newmode.name    = new_id_from_chars("ANY", 3);
	newmode.code    = irm_ANY;

	mode_ANY = register_mode(&newmode);

	/* BAD */
	newmode.name    = new_id_from_chars("BAD", 3);
	newmode.code    = irm_BAD;

	mode_BAD = register_mode(&newmode);

	/* Internal Boolean Modes */
	newmode.sort    = irms_internal_boolean;

	/* boolean */
	newmode.name    = new_id_from_chars("b", 1);
	newmode.code    = irm_b;

	mode_b = register_mode(&newmode);

	/* Data Modes */
	newmode.vector_elem = 1;

	/* Float Number Modes */
	newmode.sort       = irms_float_number;
	newmode.arithmetic = irma_ieee754;

	/* float */
	newmode.name    = new_id_from_chars("F", 1);
	newmode.code    = irm_F;
	newmode.sign    = 1;
	newmode.size    = 32;

	mode_F = register_mode(&newmode);

	/* double */
	newmode.name    = new_id_from_chars("D", 1);
	newmode.code    = irm_D;
	newmode.sign    = 1;
	newmode.size    = 64;

	mode_D = register_mode(&newmode);

	/* extended */
	newmode.name    = new_id_from_chars("E", 1);
	newmode.code    = irm_E;
	newmode.sign    = 1;
	newmode.size    = 80;

	mode_E = register_mode(&newmode);

	/* Integer Number Modes */
	newmode.sort         = irms_int_number;
	newmode.arithmetic   = irma_twos_complement;

	/* signed byte */
	newmode.name         = new_id_from_chars("Bs", 2);
	newmode.code         = irm_Bs;
	newmode.sign         = 1;
	newmode.size         = 8;
	newmode.modulo_shift = 32;

	mode_Bs = register_mode(&newmode);

	/* unsigned byte */
	newmode.name         = new_id_from_chars("Bu", 2);
	newmode.code         = irm_Bu;
	newmode.arithmetic   = irma_twos_complement;
	newmode.sign         = 0;
	newmode.size         = 8;
	newmode.modulo_shift = 32;

	mode_Bu = register_mode(&newmode);

	/* signed short integer */
	newmode.name         = new_id_from_chars("Hs", 2);
	newmode.code         = irm_Hs;
	newmode.sign         = 1;
	newmode.size         = 16;
	newmode.modulo_shift = 32;

	mode_Hs = register_mode(&newmode);

	/* unsigned short integer */
	newmode.name         = new_id_from_chars("Hu", 2);
	newmode.code         = irm_Hu;
	newmode.sign         = 0;
	newmode.size         = 16;
	newmode.modulo_shift = 32;

	mode_Hu = register_mode(&newmode);

	/* signed integer */
	newmode.name         = new_id_from_chars("Is", 2);
	newmode.code         = irm_Is;
	newmode.sign         = 1;
	newmode.size         = 32;
	newmode.modulo_shift = 32;

	mode_Is = register_mode(&newmode);

	/* unsigned integer */
	newmode.name         = new_id_from_chars("Iu", 2);
	newmode.code         = irm_Iu;
	newmode.sign         = 0;
	newmode.size         = 32;
	newmode.modulo_shift = 32;

	mode_Iu = register_mode(&newmode);

	/* signed long integer */
	newmode.name         = new_id_from_chars("Ls", 2);
	newmode.code         = irm_Ls;
	newmode.sign         = 1;
	newmode.size         = 64;
	newmode.modulo_shift = 64;

	mode_Ls = register_mode(&newmode);

	/* unsigned long integer */
	newmode.name         = new_id_from_chars("Lu", 2);
	newmode.code         = irm_Lu;
	newmode.sign         = 0;
	newmode.size         = 64;
	newmode.modulo_shift = 64;

	mode_Lu = register_mode(&newmode);

	/* signed long long integer */
	newmode.name         = new_id_from_chars("LLs", 3);
	newmode.code         = irm_LLs;
	newmode.sign         = 1;
	newmode.size         = 128;
	newmode.modulo_shift = 128;

	mode_LLs = register_mode(&newmode);

	/* unsigned long long integer */
	newmode.name         = new_id_from_chars("LLu", 3);
	newmode.code         = irm_LLu;
	newmode.sign         = 0;
	newmode.size         = 128;
	newmode.modulo_shift = 128;

	mode_LLu = register_mode(&newmode);

	/* Reference Mode */
	newmode.sort       = irms_reference;
	newmode.arithmetic = irma_twos_complement;

	/* pointer */
	newmode.name         = new_id_from_chars("P", 1);
	newmode.code         = irm_P;
	newmode.sign         = 0;
	newmode.size         = 32;
	newmode.modulo_shift = 0;
	newmode.eq_signed    = mode_Is;
	newmode.eq_unsigned  = mode_Iu;

	mode_P = register_mode(&newmode);

	/* set the machine specific modes to the predefined ones */
	mode_P_code = mode_P;
	mode_P_data = mode_P;
}

/* find a signed mode for an unsigned integer mode */
ir_mode *find_unsigned_mode(const ir_mode *mode) {
	ir_mode n = *mode;

	assert(mode->sort == irms_int_number);
	n.sign = 0;
	return find_mode(&n);
}

/* find an unsigned mode for a signed integer mode */
ir_mode *find_signed_mode(const ir_mode *mode) {
	ir_mode n = *mode;

	assert(mode->sort == irms_int_number);
	n.sign = 1;
	return find_mode(&n);
}

/* finds a integer mode with 2*n bits for an integer mode with n bits. */
ir_mode *find_double_bits_int_mode(const ir_mode *mode) {
	ir_mode n = *mode;

	assert(mode->sort == irms_int_number && mode->arithmetic == irma_twos_complement);

	n.size = 2*mode->size;
	return find_mode(&n);
}

/*
 * Returns non-zero if the given mode honors signed zero's, i.e.,
 * a +0 and a -0 exists and handled differently.
 */
int mode_honor_signed_zeros(const ir_mode *mode) {
	/* for floating point, we know that IEEE 754 has +0 and -0,
	 * but always handles it identical.
	 */
	return
		mode->sort == irms_float_number &&
		mode->arithmetic != irma_ieee754;
}

/*
 * Returns non-zero if the given mode might overflow on unary Minus.
 *
 * This does NOT happen on IEEE 754.
 */
int mode_overflow_on_unary_Minus(const ir_mode *mode) {
	if (mode->sort == irms_float_number)
		return mode->arithmetic == irma_ieee754 ? 0 : 1;
	return 1;
}

/*
 * Returns non-zero if the mode has a reversed wrap-around
 * logic, especially (a + x) - x == a.
 *
 * This is normally true for integer modes, not for floating
 * point modes.
 */
int mode_wrap_around(const ir_mode *mode) {
	/* FIXME: better would be an extra mode property */
	return mode_is_int(mode);
}

void finish_mode(void) {
	obstack_free(&modes, 0);
	DEL_ARR_F(mode_list);

	mode_T   = NULL;
	mode_X   = NULL;
	mode_M   = NULL;
	mode_BB  = NULL;
	mode_ANY = NULL;
	mode_BAD = NULL;

	mode_F   = NULL;
	mode_D   = NULL;
	mode_E   = NULL;

	mode_Bs  = NULL;
	mode_Bu  = NULL;
	mode_Hs  = NULL;
	mode_Hu  = NULL;
	mode_Is  = NULL;
	mode_Iu  = NULL;
	mode_Ls  = NULL;
	mode_Lu  = NULL;

	mode_b   = NULL;

	mode_P      = NULL;
	mode_P_code = NULL;
	mode_P_data = NULL;
}