modules/arch/x86/x86bc.c

/*
 * x86 bytecode utility functions
 *
 *  Copyright (C) 2001  Peter Johnson
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND OTHER CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR OTHER CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
#include <util.h>
/*@unused@*/ RCSID("$Id$");

#define YASM_LIB_INTERNAL
#define YASM_BC_INTERNAL
#define YASM_EXPR_INTERNAL
#include <libyasm.h>

#include "x86arch.h"


/* Effective address callback function prototypes */

static void x86_ea_destroy(yasm_effaddr *ea);
static void x86_ea_print(const yasm_effaddr *ea, FILE *f, int indent_level);

/* Bytecode callback function prototypes */

static void x86_bc_insn_destroy(void *contents);
static void x86_bc_insn_print(const void *contents, FILE *f,
			      int indent_level);
static yasm_bc_resolve_flags x86_bc_insn_resolve
    (yasm_bytecode *bc, int save, yasm_calc_bc_dist_func calc_bc_dist);
static int x86_bc_insn_tobytes(yasm_bytecode *bc, unsigned char **bufp,
			       void *d, yasm_output_value_func output_value,
			       /*@null@*/ yasm_output_reloc_func output_reloc);

static void x86_bc_jmp_destroy(void *contents);
static void x86_bc_jmp_print(const void *contents, FILE *f, int indent_level);
static yasm_bc_resolve_flags x86_bc_jmp_resolve
    (yasm_bytecode *bc, int save, yasm_calc_bc_dist_func calc_bc_dist);
static int x86_bc_jmp_tobytes(yasm_bytecode *bc, unsigned char **bufp,
			      void *d, yasm_output_value_func output_value,
			      /*@null@*/ yasm_output_reloc_func output_reloc);

static void x86_bc_jmpfar_destroy(void *contents);
static void x86_bc_jmpfar_print(const void *contents, FILE *f,
				int indent_level);
static yasm_bc_resolve_flags x86_bc_jmpfar_resolve
    (yasm_bytecode *bc, int save, yasm_calc_bc_dist_func calc_bc_dist);
static int x86_bc_jmpfar_tobytes
    (yasm_bytecode *bc, unsigned char **bufp, void *d,
     yasm_output_value_func output_value,
     /*@null@*/ yasm_output_reloc_func output_reloc);

/* Effective address callback structures */

static const yasm_effaddr_callback x86_ea_callback = {
    x86_ea_destroy,
    x86_ea_print
};

/* Bytecode callback structures */

static const yasm_bytecode_callback x86_bc_callback_insn = {
    x86_bc_insn_destroy,
    x86_bc_insn_print,
    yasm_bc_finalize_common,
    x86_bc_insn_resolve,
    x86_bc_insn_tobytes
};

static const yasm_bytecode_callback x86_bc_callback_jmp = {
    x86_bc_jmp_destroy,
    x86_bc_jmp_print,
    yasm_bc_finalize_common,
    x86_bc_jmp_resolve,
    x86_bc_jmp_tobytes
};

static const yasm_bytecode_callback x86_bc_callback_jmpfar = {
    x86_bc_jmpfar_destroy,
    x86_bc_jmpfar_print,
    yasm_bc_finalize_common,
    x86_bc_jmpfar_resolve,
    x86_bc_jmpfar_tobytes
};

int
yasm_x86__set_rex_from_reg(unsigned char *rex, unsigned char *low3,
			   unsigned long reg, unsigned int bits,
			   x86_rex_bit_pos rexbit)
{
    *low3 = (unsigned char)(reg&7);

    if (bits == 64) {
	x86_expritem_reg_size size = (x86_expritem_reg_size)(reg & ~0xFUL);

	if (size == X86_REG8X || (reg & 0xF) >= 8) {
	    if (*rex == 0xff)
		return 1;
	    *rex |= 0x40 | (((reg & 8) >> 3) << rexbit);
	} else if (size == X86_REG8 && (reg & 7) >= 4) {
	    /* AH/BH/CH/DH, so no REX allowed */
	    if (*rex != 0 && *rex != 0xff)
		return 1;
	    *rex = 0xff;
	}
    }

    return 0;
}

void
yasm_x86__bc_transform_insn(yasm_bytecode *bc, x86_insn *insn)
{
    yasm_bc_transform(bc, &x86_bc_callback_insn, insn);
}

void
yasm_x86__bc_transform_jmp(yasm_bytecode *bc, x86_jmp *jmp)
{
    yasm_bc_transform(bc, &x86_bc_callback_jmp, jmp);
}

void
yasm_x86__bc_transform_jmpfar(yasm_bytecode *bc, x86_jmpfar *jmpfar)
{
    yasm_bc_transform(bc, &x86_bc_callback_jmpfar, jmpfar);
}

void
yasm_x86__ea_init(x86_effaddr *x86_ea, unsigned int spare, unsigned long line)
{
    if (yasm_value_finalize(&x86_ea->ea.disp))
	yasm__error(line, N_("effective address too complex"));
    x86_ea->modrm &= 0xC7;		    /* zero spare/reg bits */
    x86_ea->modrm |= (spare << 3) & 0x38;   /* plug in provided bits */
}

void
yasm_x86__ea_set_disponly(x86_effaddr *x86_ea)
{
    x86_ea->valid_modrm = 0;
    x86_ea->need_modrm = 0;
    x86_ea->valid_sib = 0;
    x86_ea->need_sib = 0;
}

x86_effaddr *
yasm_x86__ea_create_reg(unsigned long reg, unsigned char *rex,
			unsigned int bits)
{
    x86_effaddr *x86_ea;
    unsigned char rm;

    if (yasm_x86__set_rex_from_reg(rex, &rm, reg, bits, X86_REX_B))
	return NULL;

    x86_ea = yasm_xmalloc(sizeof(x86_effaddr));

    x86_ea->ea.callback = &x86_ea_callback;
    yasm_value_initialize(&x86_ea->ea.disp, NULL);
    x86_ea->ea.disp_len = 0;
    x86_ea->ea.need_disp = 0;
    x86_ea->ea.nosplit = 0;
    x86_ea->ea.strong = 0;
    x86_ea->ea.segreg = 0;
    x86_ea->modrm = 0xC0 | rm;	/* Mod=11, R/M=Reg, Reg=0 */
    x86_ea->valid_modrm = 1;
    x86_ea->need_modrm = 1;
    x86_ea->sib = 0;
    x86_ea->valid_sib = 0;
    x86_ea->need_sib = 0;

    return x86_ea;
}

yasm_effaddr *
yasm_x86__ea_create_expr(yasm_arch *arch, yasm_expr *e)
{
    yasm_arch_x86 *arch_x86 = (yasm_arch_x86 *)arch;
    x86_effaddr *x86_ea;

    x86_ea = yasm_xmalloc(sizeof(x86_effaddr));

    x86_ea->ea.callback = &x86_ea_callback;
    if (arch_x86->parser == X86_PARSER_GAS) {
	/* Need to change foo+rip into foo wrt rip.
	 * Note this assumes a particular ordering coming from the parser
	 * to work (it's not very smart)!
	 */
	if (e->op == YASM_EXPR_ADD && e->terms[0].type == YASM_EXPR_REG
	    && e->terms[0].data.reg == X86_RIP) {
	    /* replace register with 0 */
	    e->terms[0].type = YASM_EXPR_INT;
	    e->terms[0].data.intn = yasm_intnum_create_uint(0);
	    /* build new wrt expression */
	    e = yasm_expr_create(YASM_EXPR_WRT, yasm_expr_expr(e),
				 yasm_expr_reg(X86_RIP), e->line);
	}
    }
    yasm_value_initialize(&x86_ea->ea.disp, e);
    x86_ea->ea.disp_len = 0;
    x86_ea->ea.need_disp = 1;
    x86_ea->ea.nosplit = 0;
    x86_ea->ea.strong = 0;
    x86_ea->ea.segreg = 0;
    x86_ea->modrm = 0;
    x86_ea->valid_modrm = 0;
    x86_ea->need_modrm = 1;
    x86_ea->sib = 0;
    x86_ea->valid_sib = 0;
    /* We won't know whether we need an SIB until we know more about expr and
     * the BITS/address override setting.
     */
    x86_ea->need_sib = 0xff;

    return (yasm_effaddr *)x86_ea;
}

/*@-compmempass@*/
x86_effaddr *
yasm_x86__ea_create_imm(yasm_expr *imm, unsigned int im_len)
{
    x86_effaddr *x86_ea;

    x86_ea = yasm_xmalloc(sizeof(x86_effaddr));

    x86_ea->ea.callback = &x86_ea_callback;
    yasm_value_initialize(&x86_ea->ea.disp, imm);
    x86_ea->ea.disp_len = (unsigned char)im_len;
    x86_ea->ea.need_disp = 1;
    x86_ea->ea.nosplit = 0;
    x86_ea->ea.strong = 0;
    x86_ea->ea.segreg = 0;
    x86_ea->modrm = 0;
    x86_ea->valid_modrm = 0;
    x86_ea->need_modrm = 0;
    x86_ea->sib = 0;
    x86_ea->valid_sib = 0;
    x86_ea->need_sib = 0;

    return x86_ea;
}
/*@=compmempass@*/

void
yasm_x86__bc_apply_prefixes(x86_common *common, unsigned char *rex,
			    int num_prefixes, unsigned long **prefixes,
			    unsigned long line)
{
    int i;
    int first = 1;

    for (i=0; i<num_prefixes; i++) {
	switch ((x86_parse_insn_prefix)prefixes[i][0]) {
	    case X86_LOCKREP:
		if (common->lockrep_pre != 0)
		    yasm__warning(YASM_WARN_GENERAL, line,
			N_("multiple LOCK or REP prefixes, using leftmost"));
		common->lockrep_pre = (unsigned char)prefixes[i][1];
		break;
	    case X86_ADDRSIZE:
		common->addrsize = (unsigned char)prefixes[i][1];
		break;
	    case X86_OPERSIZE:
		common->opersize = (unsigned char)prefixes[i][1];
		break;
	    case X86_SEGREG:
		/* This is a hack.. we should really be putting this in the
		 * the effective address!
		 */
		common->lockrep_pre = (unsigned char)prefixes[i][1];
		break;
	    case X86_REX:
		if (!rex)
		    yasm__warning(YASM_WARN_GENERAL, line,
			N_("ignoring REX prefix on jump"));
		else if (*rex == 0xff)
		    yasm__warning(YASM_WARN_GENERAL, line,
			N_("REX prefix not allowed on this instruction, ignoring"));
		else {
		    if (*rex != 0) {
			if (first)
			    yasm__warning(YASM_WARN_GENERAL, line,
				N_("overriding generated REX prefix"));
			else
			    yasm__warning(YASM_WARN_GENERAL, line,
				N_("multiple REX prefixes, using leftmost"));
		    }
		    /* Here we assume that we can't get this prefix in non
		     * 64 bit mode due to checks in parse_check_prefix().
		     */
		    common->mode_bits = 64;
		    *rex = (unsigned char)prefixes[i][1];
		}
		first = 0;
		break;
	}
    }
}

static void
x86_bc_insn_destroy(void *contents)
{
    x86_insn *insn = (x86_insn *)contents;
    if (insn->x86_ea)
	yasm_ea_destroy((yasm_effaddr *)insn->x86_ea);
    if (insn->imm) {
	yasm_value_delete(&insn->imm->val);
	yasm_xfree(insn->imm);
    }
    yasm_xfree(contents);
}

static void
x86_bc_jmp_destroy(void *contents)
{
    x86_jmp *jmp = (x86_jmp *)contents;
    yasm_value_delete(&jmp->target);
    yasm_xfree(contents);
}

static void
x86_bc_jmpfar_destroy(void *contents)
{
    x86_jmpfar *jmpfar = (x86_jmpfar *)contents;
    yasm_value_delete(&jmpfar->segment);
    yasm_value_delete(&jmpfar->offset);
    yasm_xfree(contents);
}

static void
x86_ea_destroy(yasm_effaddr *ea)
{
}

static void
x86_ea_print(const yasm_effaddr *ea, FILE *f, int indent_level)
{
    const x86_effaddr *x86_ea = (const x86_effaddr *)ea;
    fprintf(f, "%*sSegmentOv=%02x\n", indent_level, "",
	    (unsigned int)x86_ea->ea.segreg);
    fprintf(f, "%*sModRM=%03o ValidRM=%u NeedRM=%u\n", indent_level, "",
	    (unsigned int)x86_ea->modrm, (unsigned int)x86_ea->valid_modrm,
	    (unsigned int)x86_ea->need_modrm);
    fprintf(f, "%*sSIB=%03o ValidSIB=%u NeedSIB=%u\n", indent_level, "",
	    (unsigned int)x86_ea->sib, (unsigned int)x86_ea->valid_sib,
	    (unsigned int)x86_ea->need_sib);
}

static void
x86_common_print(const x86_common *common, FILE *f, int indent_level)
{
    fprintf(f, "%*sAddrSize=%u OperSize=%u LockRepPre=%02x BITS=%u\n",
	    indent_level, "",
	    (unsigned int)common->addrsize,
	    (unsigned int)common->opersize,
	    (unsigned int)common->lockrep_pre,
	    (unsigned int)common->mode_bits);
}

static void
x86_opcode_print(const x86_opcode *opcode, FILE *f, int indent_level)
{
    fprintf(f, "%*sOpcode: %02x %02x %02x OpLen=%u\n", indent_level, "",
	    (unsigned int)opcode->opcode[0],
	    (unsigned int)opcode->opcode[1],
	    (unsigned int)opcode->opcode[2],
	    (unsigned int)opcode->len);
}

static void
x86_bc_insn_print(const void *contents, FILE *f, int indent_level)
{
    const x86_insn *insn = (const x86_insn *)contents;

    fprintf(f, "%*s_Instruction_\n", indent_level, "");
    fprintf(f, "%*sEffective Address:", indent_level, "");
    if (insn->x86_ea) {
	fprintf(f, "\n");
	yasm_ea_print((yasm_effaddr *)insn->x86_ea, f, indent_level+1);
    } else
	fprintf(f, " (nil)\n");
    fprintf(f, "%*sImmediate Value:", indent_level, "");
    if (!insn->imm)
	fprintf(f, " (nil)\n");
    else {
	indent_level++;
	fprintf(f, "\n");
	yasm_value_print(&insn->imm->val, f, indent_level);
	fprintf(f, "%*sLen=%u, Sign=%u\n", indent_level, "",
		(unsigned int)insn->imm->len,
		(unsigned int)insn->imm->sign);
	indent_level--;
    }
    x86_opcode_print(&insn->opcode, f, indent_level);
    x86_common_print(&insn->common, f, indent_level);
    fprintf(f, "%*sSpPre=%02x REX=%03o PostOp=%u\n", indent_level, "",
	    (unsigned int)insn->special_prefix,
	    (unsigned int)insn->rex,
	    (unsigned int)insn->postop);
}

static void
x86_bc_jmp_print(const void *contents, FILE *f, int indent_level)
{
    const x86_jmp *jmp = (const x86_jmp *)contents;

    fprintf(f, "%*s_Jump_\n", indent_level, "");
    fprintf(f, "%*sTarget:\n", indent_level, "");
    yasm_value_print(&jmp->target, f, indent_level+1);
    /* FIXME
    fprintf(f, "%*sOrigin=\n", indent_level, "");
    yasm_symrec_print(jmp->origin, f, indent_level+1);
    */
    fprintf(f, "\n%*sShort Form:\n", indent_level, "");
    if (jmp->shortop.len == 0)
	fprintf(f, "%*sNone\n", indent_level+1, "");
    else
	x86_opcode_print(&jmp->shortop, f, indent_level+1);
    fprintf(f, "%*sNear Form:\n", indent_level, "");
    if (jmp->nearop.len == 0)
	fprintf(f, "%*sNone\n", indent_level+1, "");
    else
	x86_opcode_print(&jmp->nearop, f, indent_level+1);
    fprintf(f, "%*sOpSel=", indent_level, "");
    switch (jmp->op_sel) {
	case JMP_NONE:
	    fprintf(f, "None");
	    break;
	case JMP_SHORT:
	    fprintf(f, "Short");
	    break;
	case JMP_NEAR:
	    fprintf(f, "Near");
	    break;
	case JMP_SHORT_FORCED:
	    fprintf(f, "Forced Short");
	    break;
	case JMP_NEAR_FORCED:
	    fprintf(f, "Forced Near");
	    break;
	default:
	    fprintf(f, "UNKNOWN!!");
	    break;
    }
    x86_common_print(&jmp->common, f, indent_level);
}

static void
x86_bc_jmpfar_print(const void *contents, FILE *f, int indent_level)
{
    const x86_jmpfar *jmpfar = (const x86_jmpfar *)contents;

    fprintf(f, "%*s_Far_Jump_\n", indent_level, "");
    fprintf(f, "%*sSegment:\n", indent_level, "");
    yasm_value_print(&jmpfar->segment, f, indent_level+1);
    fprintf(f, "%*sOffset:\n", indent_level, "");
    yasm_value_print(&jmpfar->offset, f, indent_level+1);
    x86_opcode_print(&jmpfar->opcode, f, indent_level);
    x86_common_print(&jmpfar->common, f, indent_level);
}

static unsigned int
x86_common_resolve(const x86_common *common)
{
    unsigned int len = 0;

    if (common->addrsize != 0 && common->addrsize != common->mode_bits)
	len++;
    if (common->opersize != 0 &&
	((common->mode_bits != 64 && common->opersize != common->mode_bits) ||
	 (common->mode_bits == 64 && common->opersize == 16)))
	len++;
    if (common->lockrep_pre != 0)
	len++;

    return len;
}

static yasm_bc_resolve_flags
x86_bc_insn_resolve(yasm_bytecode *bc, int save,
		    yasm_calc_bc_dist_func calc_bc_dist)
{
    x86_insn *insn = (x86_insn *)bc->contents;
    x86_effaddr *x86_ea = insn->x86_ea;
    yasm_immval *imm = insn->imm;
    yasm_bc_resolve_flags retval = YASM_BC_RESOLVE_MIN_LEN;

    if (x86_ea) {
	/* Create temp copy of disp, etc. */
	x86_effaddr eat = *x86_ea;	/* structure copy */

	/* Don't overwrite original expression portion */
	if (x86_ea->ea.disp.abs)
	    eat.ea.disp.abs = yasm_expr_copy(x86_ea->ea.disp.abs);

	/* Handle shortmov special-casing */
	if (insn->postop == X86_POSTOP_SHORTMOV &&
	    insn->common.mode_bits == 64 && insn->common.addrsize == 32 &&
	    (!eat.ea.disp.abs ||
	     !yasm_expr__contains(eat.ea.disp.abs, YASM_EXPR_REG))) {
	    yasm_x86__ea_set_disponly(&eat);

	    if (save) {
		/* Make the short form permanent. */
		insn->opcode.opcode[0] = insn->opcode.opcode[1];
	    }
	}

	/* Check validity of effective address and calc R/M bits of
	 * Mod/RM byte and SIB byte.  We won't know the Mod field
	 * of the Mod/RM byte until we know more about the
	 * displacement.
	 */
	switch (yasm_x86__expr_checkea(&eat, &insn->common.addrsize,
		insn->common.mode_bits, insn->postop == X86_POSTOP_ADDRESS16,
		&insn->rex, calc_bc_dist, bc->line)) {
	    case 1:
		yasm_expr_destroy(eat.ea.disp.abs);
		/* failed, don't bother checking rest of insn */
		return YASM_BC_RESOLVE_UNKNOWN_LEN|YASM_BC_RESOLVE_ERROR;
	    case 2:
		yasm_expr_destroy(eat.ea.disp.abs);
		/* failed, don't bother checking rest of insn */
		return YASM_BC_RESOLVE_UNKNOWN_LEN;
	    default:
		yasm_expr_destroy(eat.ea.disp.abs);
		/* okay */
		break;
	}

	if (eat.ea.disp_len != 1) {
	    /* Fits into a word/dword, or unknown. */
	    retval = YASM_BC_RESOLVE_NONE;  /* may not be smallest size */

	    /* Handle unknown case, make displen word-sized */
	    if (eat.ea.disp_len == 0xff)
		eat.ea.disp_len = (insn->common.addrsize == 16) ? 2U : 4U;
	}

	/* Handle address16 postop case */
	if (insn->postop == X86_POSTOP_ADDRESS16)
	    insn->common.addrsize = 0;

	/* If we had forced ea->len but had to override, save it now */
	if (x86_ea->ea.disp_len != 0 && x86_ea->ea.disp_len != eat.ea.disp_len)
	    x86_ea->ea.disp_len = eat.ea.disp_len;

	if (save) {
	    eat.ea.disp.abs = x86_ea->ea.disp.abs; /* Copy back original */
	    *x86_ea = eat;	/* structure copy */
	    if (x86_ea->ea.disp_len == 0) {
		yasm_value_delete(&x86_ea->ea.disp);
		x86_ea->ea.need_disp = 0;
	    }
	}

	/* Compute length of ea and add to total */
	bc->len += eat.need_modrm + (eat.need_sib ? 1:0) + eat.ea.disp_len;
	bc->len += (eat.ea.segreg != 0) ? 1 : 0;
    }

    if (imm) {
	/*@null@*/ yasm_expr *temp = NULL;
	const yasm_intnum *num = NULL;
	unsigned int immlen = imm->len;
	long val;

	if (imm->val.abs) {
	    temp = yasm_expr_copy(imm->val.abs);
	    assert(temp != NULL);
	    num = yasm_expr_get_intnum(&temp, calc_bc_dist);
	}

	/* TODO: check imm->len vs. sized len from expr? */

	switch (insn->postop) {
	    case X86_POSTOP_SIGNEXT_IMM8:
		/* Handle signext_imm8 postop special-casing */
		if (imm->val.rel)
		    val = 1000;	    /* has relative portion, don't collapse */
		else if (num)
		    val = yasm_intnum_get_int(num);
		else
		    val = 0;
		if (val >= -128 && val <= 127) {
		    /* We can use the sign-extended byte form: shorten
		     * the immediate length to 1.
		     */
		    immlen = 1;
		    if (save) {
			/* Make the byte form permanent. */
			insn->opcode.opcode[0] = insn->opcode.opcode[1];
			imm->len = 1;
			if (insn->opcode.opcode[2] != 0) {
			    insn->opcode.opcode[1] = insn->opcode.opcode[2];
			    insn->opcode.len++;
			}
		    } else if (insn->opcode.opcode[2] != 0)
			bc->len++;
		}
		/* Not really necessary, but saves confusion over it. */
		if (save)
		    insn->postop = X86_POSTOP_NONE;
		break;

	    case X86_POSTOP_SIGNEXT_IMM32:
		/* Handle signext_imm32 postop special-casing */
		if (!num || yasm_intnum_check_size(num, 32, 0, 1)) {
		    bc->len++;  /* Due to ModRM byte */
		    immlen = 4;
		    if (save) {
			/* Throwaway REX byte */
			unsigned char rex_temp = 0;

			/* Build ModRM EA - CAUTION: this depends on
			 * opcode 0 being a mov instruction!
			 */
			insn->x86_ea = yasm_x86__ea_create_reg(
			    (unsigned long)insn->opcode.opcode[0]-0xB8,
			    &rex_temp, 64);

			/* Make the imm32s form permanent. */
			insn->opcode.opcode[0] = insn->opcode.opcode[1];
			imm->len = 4;
		    }
		}
		/* Not really necessary, but saves confusion over it. */
		if (save)
		    insn->postop = X86_POSTOP_NONE;
		break;

	    case X86_POSTOP_SHIFT:
		/* Handle shift postop special-casing */
		if (num && yasm_intnum_get_uint(num) == 1) {
		    /* We can use the ,1 form: no imm (set to 0 len) */
		    immlen = 0;

		    if (save) {
			/* Make the ,1 form permanent. */
			insn->opcode.opcode[0] = insn->opcode.opcode[1];
			/* Delete imm, as it's not needed. */
			yasm_value_delete(&imm->val);
			yasm_xfree(imm);
			insn->imm = (yasm_immval *)NULL;
		    }
		} else
		    retval = YASM_BC_RESOLVE_NONE;  /* could still get ,1 */

		/* Not really necessary, but saves confusion over it. */
		if (save)
		    insn->postop = X86_POSTOP_NONE;
		break;

	    default:
		break;
	}

	yasm_expr_destroy(temp);

	bc->len += immlen;
    }

    bc->len += insn->opcode.len;
    bc->len += x86_common_resolve(&insn->common);
    bc->len += (insn->special_prefix != 0) ? 1:0;
    if (insn->rex != 0xff &&
	(insn->rex != 0 ||
	 (insn->common.mode_bits == 64 && insn->common.opersize == 64 &&
	  insn->def_opersize_64 != 64)))
	bc->len++;

    return retval;
}

static yasm_bc_resolve_flags
x86_bc_jmp_resolve(yasm_bytecode *bc, int save,
		   yasm_calc_bc_dist_func calc_bc_dist)
{
    x86_jmp *jmp = (x86_jmp *)bc->contents;
    yasm_bc_resolve_flags retval = YASM_BC_RESOLVE_MIN_LEN;
    yasm_bytecode *target_prevbc;
    /*@null@*/ yasm_expr *temp;
    /*@only@*/ yasm_intnum *num;
    /*@dependent@*/ /*@null@*/ yasm_intnum *num2;
    long rel;
    unsigned char opersize;
    x86_jmp_opcode_sel jrtype = JMP_NONE;

    /* As opersize may be 0, figure out its "real" value. */
    opersize = (jmp->common.opersize == 0) ?
	jmp->common.mode_bits : jmp->common.opersize;

    /* We only check to see if forced forms are actually legal if we're in
     * save mode.  Otherwise we assume that they are legal.
     */
    switch (jmp->op_sel) {
	case JMP_SHORT_FORCED:
	    /* 1 byte relative displacement */
	    jrtype = JMP_SHORT;
	    if (save) {
		/* does a short form exist? */
		if (jmp->shortop.len == 0) {
		    yasm__error(bc->line, N_("short jump does not exist"));
		    return YASM_BC_RESOLVE_ERROR | YASM_BC_RESOLVE_UNKNOWN_LEN;
		}

		if (!jmp->target.rel)
		    num = yasm_intnum_create_uint(0);
		else if (!yasm_symrec_get_label(jmp->target.rel, &target_prevbc)
			 || target_prevbc->section != jmp->origin_prevbc->section
			 || !(num = calc_bc_dist(jmp->origin_prevbc,
						 target_prevbc))) {
		    /* External or out of segment, so we can't check distance.
		     * This depends on the objfmt supporting 8-bit relocs.
		     * While most don't, some might, so allow it.  The objfmt
		     * will error if not supported.
		     */
		    break;
		}

		if (jmp->target.abs) {
		    temp = yasm_expr_copy(jmp->target.abs);
		    num2 = yasm_expr_get_intnum(&temp, calc_bc_dist);
		    if (!num2) {
			yasm_expr_destroy(temp);
			yasm__error(bc->line, N_("jump target too complex"));
			return YASM_BC_RESOLVE_ERROR |
			    YASM_BC_RESOLVE_UNKNOWN_LEN;
		    }
		    yasm_intnum_calc(num, YASM_EXPR_ADD, num2, bc->line);
		    yasm_expr_destroy(temp);
		}

		rel = yasm_intnum_get_int(num);
		yasm_intnum_destroy(num);
		rel -= jmp->shortop.len+1;
		/* short displacement must fit in -128 <= rel <= +127 */
		if (rel < -128 || rel > 127) {
		    yasm__error(bc->line, N_("short jump out of range"));
		    return YASM_BC_RESOLVE_ERROR | YASM_BC_RESOLVE_UNKNOWN_LEN;
		}
	    }
	    break;
	case JMP_NEAR_FORCED:
	    /* 2/4 byte relative displacement (depending on operand size) */
	    jrtype = JMP_NEAR;
	    if (save) {
		if (jmp->nearop.len == 0) {
		    yasm__error(bc->line, N_("near jump does not exist"));
		    return YASM_BC_RESOLVE_ERROR | YASM_BC_RESOLVE_UNKNOWN_LEN;
		}
	    }
	    break;
	default:
	    /* Due to code in x86_finalize_jmp(), we can only get here if
	     * there's BOTH short and near opcodes available, and it wasn't
	     * forced by the user.
	     */
	    if (!jmp->target.rel)
		num = yasm_intnum_create_uint(0);
	    else if (!yasm_symrec_get_label(jmp->target.rel, &target_prevbc)
		     || target_prevbc->section != jmp->origin_prevbc->section
		     || !(num = calc_bc_dist(jmp->origin_prevbc,
					     target_prevbc))) {
		/* It's unknown.  Thus, assume near displacement. */
		jrtype = JMP_NEAR;
		retval = YASM_BC_RESOLVE_NONE;
		break;
	    }

	    /* Try to find shortest displacement based on difference between
	     * target expr value and origin offset.
	     */
	    if (jmp->target.abs) {
		temp = yasm_expr_copy(jmp->target.abs);
		num2 = yasm_expr_get_intnum(&temp, calc_bc_dist);
		if (!num2) {
		    yasm_expr_destroy(temp);
		    yasm__error(bc->line, N_("jump target too complex"));
		    return YASM_BC_RESOLVE_ERROR | YASM_BC_RESOLVE_UNKNOWN_LEN;
		}
		yasm_intnum_calc(num, YASM_EXPR_ADD, num2, bc->line);
		yasm_expr_destroy(temp);
	    }

	    rel = yasm_intnum_get_int(num);
	    yasm_intnum_destroy(num);
	    rel -= jmp->shortop.len+1;
	    /* short displacement must fit within -128 <= rel <= +127 */
	    if (rel >= -128 && rel <= 127) {
		/* It fits into a short displacement. */
		jrtype = JMP_SHORT;
	    } else {
		/* Near for now, but could get shorter in the future as
		 * there's a short form available.
		 */
		jrtype = JMP_NEAR;
		retval = YASM_BC_RESOLVE_NONE;
	    }
	    break;
    }

    switch (jrtype) {
	case JMP_SHORT:
	    if (save)
		jmp->op_sel = JMP_SHORT;
	    if (jmp->shortop.len == 0)
		return YASM_BC_RESOLVE_UNKNOWN_LEN; /* size not available */

	    bc->len += jmp->shortop.len + 1;
	    break;
	case JMP_NEAR:
	    if (save)
		jmp->op_sel = JMP_NEAR;
	    if (jmp->nearop.len == 0)
		return YASM_BC_RESOLVE_UNKNOWN_LEN; /* size not available */

	    bc->len += jmp->nearop.len;
	    bc->len += (opersize == 16) ? 2 : 4;
	    break;
	default:
	    yasm_internal_error(N_("unknown jump type"));
    }
    bc->len += x86_common_resolve(&jmp->common);

    return retval;
}

static yasm_bc_resolve_flags
x86_bc_jmpfar_resolve(yasm_bytecode *bc, int save,
		      yasm_calc_bc_dist_func calc_bc_dist)
{
    x86_jmpfar *jmpfar = (x86_jmpfar *)bc->contents;
    unsigned char opersize;
   
    opersize = (jmpfar->common.opersize == 0) ?
	jmpfar->common.mode_bits : jmpfar->common.opersize;

    bc->len += jmpfar->opcode.len;
    bc->len += 2;	/* segment */
    bc->len += (opersize == 16) ? 2 : 4;
    bc->len += x86_common_resolve(&jmpfar->common);

    return YASM_BC_RESOLVE_MIN_LEN;
}

static void
x86_common_tobytes(const x86_common *common, unsigned char **bufp,
		   unsigned int segreg)
{
    if (common->lockrep_pre != 0)
	YASM_WRITE_8(*bufp, common->lockrep_pre);
    if (segreg != 0)
	YASM_WRITE_8(*bufp, (unsigned char)segreg);
    if (common->opersize != 0 &&
	((common->mode_bits != 64 && common->opersize != common->mode_bits) ||
	 (common->mode_bits == 64 && common->opersize == 16)))
	YASM_WRITE_8(*bufp, 0x66);
    if (common->addrsize != 0 && common->addrsize != common->mode_bits)
	YASM_WRITE_8(*bufp, 0x67);
}

static void
x86_opcode_tobytes(const x86_opcode *opcode, unsigned char **bufp)
{
    unsigned int i;
    for (i=0; i<opcode->len; i++)
	YASM_WRITE_8(*bufp, opcode->opcode[i]);
}

static int
x86_bc_insn_tobytes(yasm_bytecode *bc, unsigned char **bufp, void *d,
		    yasm_output_value_func output_value,
		    /*@unused@*/ yasm_output_reloc_func output_reloc)
{
    x86_insn *insn = (x86_insn *)bc->contents;
    /*@null@*/ x86_effaddr *x86_ea = (x86_effaddr *)insn->x86_ea;
    yasm_immval *imm = insn->imm;
    unsigned char *bufp_orig = *bufp;

    /* Prefixes */
    if (insn->special_prefix != 0)
	YASM_WRITE_8(*bufp, insn->special_prefix);
    x86_common_tobytes(&insn->common, bufp,
		       x86_ea ? (x86_ea->ea.segreg>>8) : 0);
    if (insn->rex != 0xff) {
	if (insn->common.mode_bits == 64 && insn->common.opersize == 64 &&
	    insn->def_opersize_64 != 64)
	    insn->rex |= 0x48;
	if (insn->rex != 0) {
	    if (insn->common.mode_bits != 64)
		yasm_internal_error(
		    N_("x86: got a REX prefix in non-64-bit mode"));
	    YASM_WRITE_8(*bufp, insn->rex);
	}
    }

    /* Opcode */
    x86_opcode_tobytes(&insn->opcode, bufp);

    /* Effective address: ModR/M (if required), SIB (if required), and
     * displacement (if required).
     */
    if (x86_ea) {
	if (x86_ea->need_modrm) {
	    if (!x86_ea->valid_modrm)
		yasm_internal_error(N_("invalid Mod/RM in x86 tobytes_insn"));
	    YASM_WRITE_8(*bufp, x86_ea->modrm);
	}

	if (x86_ea->need_sib) {
	    if (!x86_ea->valid_sib)
		yasm_internal_error(N_("invalid SIB in x86 tobytes_insn"));
	    YASM_WRITE_8(*bufp, x86_ea->sib);
	}

	if (x86_ea->ea.need_disp) {
	    x86_effaddr eat = *x86_ea;  /* structure copy */
	    unsigned char addrsize = insn->common.addrsize;

	    eat.valid_modrm = 0;    /* force checkea to actually run */

	    if (x86_ea->ea.disp.abs) {
		/* Call checkea() to simplify the registers out of the
		 * displacement.  Throw away all of the return values except
		 * for the modified expr.
		 */
		if (yasm_x86__expr_checkea
		    (&eat, &addrsize, insn->common.mode_bits,
		     insn->postop == X86_POSTOP_ADDRESS16, &insn->rex,
		     yasm_common_calc_bc_dist, bc->line))
		    yasm_internal_error(N_("checkea failed"));
		x86_ea->ea.disp.abs = eat.ea.disp.abs;
	    }

	    if (x86_ea->ea.disp.ip_rel) {
		/* Adjust relative displacement to end of bytecode */
		/*@only@*/ yasm_intnum *delta;
		delta = yasm_intnum_create_int(-(long)bc->len);
		if (!x86_ea->ea.disp.abs)
		    x86_ea->ea.disp.abs =
			yasm_expr_create_ident(yasm_expr_int(delta), bc->line);
		else
		    x86_ea->ea.disp.abs =
			yasm_expr_create(YASM_EXPR_ADD,
					 yasm_expr_expr(x86_ea->ea.disp.abs),
					 yasm_expr_int(delta), bc->line);
	    }
	    if (output_value(&x86_ea->ea.disp, *bufp, x86_ea->ea.disp_len,
			     (size_t)(x86_ea->ea.disp_len*8), 0,
			     (unsigned long)(*bufp-bufp_orig), bc, 1, d))
		return 1;
	    *bufp += x86_ea->ea.disp_len;
	}
    }

    /* Immediate (if required) */
    if (imm) {
	if (output_value(&imm->val, *bufp, imm->len, (size_t)(imm->len*8), 0,
			 (unsigned long)(*bufp-bufp_orig), bc, imm->sign?-1:1,
			 d))
	    return 1;
	*bufp += imm->len;
    }

    return 0;
}

static int
x86_bc_jmp_tobytes(yasm_bytecode *bc, unsigned char **bufp, void *d,
		   yasm_output_value_func output_value,
		   /*@unused@*/ yasm_output_reloc_func output_reloc)
{
    x86_jmp *jmp = (x86_jmp *)bc->contents;
    unsigned char opersize;
    unsigned int i;
    unsigned char *bufp_orig = *bufp;
    /*@only@*/ yasm_intnum *delta;

    /* Prefixes */
    x86_common_tobytes(&jmp->common, bufp, 0);

    /* As opersize may be 0, figure out its "real" value. */
    opersize = (jmp->common.opersize == 0) ?
	jmp->common.mode_bits : jmp->common.opersize;

    /* Check here to see if forced forms are actually legal. */
    switch (jmp->op_sel) {
	case JMP_SHORT_FORCED:
	case JMP_SHORT:
	    /* 1 byte relative displacement */
	    if (jmp->shortop.len == 0)
		yasm_internal_error(N_("short jump does not exist"));

	    /* Opcode */
	    x86_opcode_tobytes(&jmp->shortop, bufp);

	    /* Adjust relative displacement to end of bytecode */
	    delta = yasm_intnum_create_int(-(long)bc->len);
	    if (!jmp->target.abs)
		jmp->target.abs = yasm_expr_create_ident(yasm_expr_int(delta),
							 bc->line);
	    else
		jmp->target.abs =
		    yasm_expr_create(YASM_EXPR_ADD,
				     yasm_expr_expr(jmp->target.abs),
				     yasm_expr_int(delta), bc->line);

	    if (output_value(&jmp->target, *bufp, 1, 8, 0,
			     (unsigned long)(*bufp-bufp_orig), bc, -1, d))
		return 1;
	    *bufp += 1;
	    break;
	case JMP_NEAR_FORCED:
	case JMP_NEAR:
	    /* 2/4 byte relative displacement (depending on operand size) */
	    if (jmp->nearop.len == 0) {
		yasm__error(bc->line, N_("near jump does not exist"));
		return 1;
	    }

	    /* Opcode */
	    x86_opcode_tobytes(&jmp->nearop, bufp);

	    i = (opersize == 16) ? 2 : 4;

	    /* Adjust relative displacement to end of bytecode */
	    delta = yasm_intnum_create_int(-(long)bc->len);
	    if (!jmp->target.abs)
		jmp->target.abs = yasm_expr_create_ident(yasm_expr_int(delta),
							 bc->line);
	    else
		jmp->target.abs =
		    yasm_expr_create(YASM_EXPR_ADD,
				     yasm_expr_expr(jmp->target.abs),
				     yasm_expr_int(delta), bc->line);

	    if (output_value(&jmp->target, *bufp, i, i*8, 0,
			     (unsigned long)(*bufp-bufp_orig), bc, -1, d))
		return 1;
	    *bufp += i;
	    break;
	default:
	    yasm_internal_error(N_("unrecognized relative jump op_sel"));
    }
    return 0;
}

static int
x86_bc_jmpfar_tobytes(yasm_bytecode *bc, unsigned char **bufp, void *d,
		      yasm_output_value_func output_value,
		      /*@unused@*/ yasm_output_reloc_func output_reloc)
{
    x86_jmpfar *jmpfar = (x86_jmpfar *)bc->contents;
    unsigned int i;
    unsigned char *bufp_orig = *bufp;
    unsigned char opersize;

    x86_common_tobytes(&jmpfar->common, bufp, 0);
    x86_opcode_tobytes(&jmpfar->opcode, bufp);

    /* As opersize may be 0, figure out its "real" value. */
    opersize = (jmpfar->common.opersize == 0) ?
	jmpfar->common.mode_bits : jmpfar->common.opersize;

    /* Absolute displacement: segment and offset */
    i = (opersize == 16) ? 2 : 4;
    if (output_value(&jmpfar->offset, *bufp, i, i*8, 0,
		     (unsigned long)(*bufp-bufp_orig), bc, 1, d))
	return 1;
    *bufp += i;
    if (output_value(&jmpfar->segment, *bufp, 2, 2*8, 0,
		     (unsigned long)(*bufp-bufp_orig), bc, 1, d))
	return 1;
    *bufp += 2;

    return 0;
}

int
yasm_x86__intnum_tobytes(yasm_arch *arch, const yasm_intnum *intn,
			 unsigned char *buf, size_t destsize, size_t valsize,
			 int shift, const yasm_bytecode *bc, int warn,
			 unsigned long line)
{
    /* Write value out. */
    yasm_intnum_get_sized(intn, buf, destsize, valsize, shift, 0, warn,
			  line);
    return 0;
}