ia32_emitter.c

/*
 * This file is part of libFirm.
 * Copyright (C) 2012 University of Karlsruhe.
 */

/**
 * @file
 * @brief       This file implements the ia32 node emitter.
 * @author      Christian Wuerdig, Matthias Braun
 *
 * Summary table for x86 floatingpoint compares:
 * (remember effect of unordered on x86: ZF=1, PF=1, CF=1)
 *
 *   pnc_Eq  => !P && E
 *   pnc_Lt  => !P && B
 *   pnc_Le  => !P && BE
 *   pnc_Gt  => A
 *   pnc_Ge  => AE
 *   pnc_Lg  => NE
 *   pnc_Leg => NP  (ordered)
 *   pnc_Uo  => P
 *   pnc_Ue  => E
 *   pnc_Ul  => B
 *   pnc_Ule => BE
 *   pnc_Ug  => P || A
 *   pnc_Uge => P || AE
 *   pnc_Ne  => P || NE
 */
#include <limits.h>
#include <inttypes.h>

#include "../../adt/util.h"
#include "xmalloc.h"
#include "tv.h"
#include "iredges.h"
#include "debug.h"
#include "irgwalk.h"
#include "irprintf.h"
#include "irop_t.h"
#include "irargs_t.h"
#include "irprog_t.h"
#include "iredges_t.h"
#include "irtools.h"
#include "execfreq.h"
#include "panic.h"
#include "dbginfo.h"
#include "lc_opts.h"
#include "ircons.h"

#include "besched.h"
#include "benode.h"
#include "beabi.h"
#include "bedwarf.h"
#include "beemitter.h"
#include "begnuas.h"
#include "beutil.h"

#include "ia32_emitter.h"
#include "ia32_common_transform.h"
#include "gen_ia32_emitter.h"
#include "gen_ia32_regalloc_if.h"
#include "ia32_nodes_attr.h"
#include "ia32_new_nodes.h"
#include "ia32_architecture.h"
#include "bearch_ia32_t.h"

DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)

static const ia32_isa_t *isa;
static char              pic_base_label[128];
static ir_label_t        exc_label_id;
static bool              mark_spill_reload;
static bool              do_pic;

static bool              sp_relative;
static int               frame_type_size;
static int               callframe_offset;

/** Return the next block in Block schedule */
static ir_node *get_prev_block_sched(const ir_node *block)
{
	return (ir_node*)get_irn_link(block);
}

/** Checks if the current block is a fall-through target. */
static int is_fallthrough(const ir_node *cfgpred)
{
	ir_node *pred;

	if (!is_Proj(cfgpred))
		return 1;
	pred = get_Proj_pred(cfgpred);
	if (is_ia32_SwitchJmp(pred))
		return 0;

	return 1;
}

/**
 * returns non-zero if the given block needs a label
 * because of being a jump-target (and not a fall-through)
 */
static int block_needs_label(const ir_node *block)
{
	int need_label = 1;
	int  n_cfgpreds = get_Block_n_cfgpreds(block);

	if (get_Block_entity(block) != NULL)
		return 1;

	if (n_cfgpreds == 0) {
		need_label = 0;
	} else if (n_cfgpreds == 1) {
		ir_node *cfgpred       = get_Block_cfgpred(block, 0);
		ir_node *cfgpred_block = get_nodes_block(cfgpred);

		if (get_prev_block_sched(block) == cfgpred_block
				&& is_fallthrough(cfgpred)) {
			need_label = 0;
		}
	}

	return need_label;
}

/**
 * Add a number to a prefix. This number will not be used a second time.
 */
static char *get_unique_label(char *buf, size_t buflen, const char *prefix)
{
	static unsigned long id = 0;
	snprintf(buf, buflen, "%s%s%lu", be_gas_get_private_prefix(), prefix, ++id);
	return buf;
}

/**
 * Emit the name of the 8bit low register
 */
static void emit_8bit_register(const arch_register_t *reg)
{
	assert(reg->index == REG_GP_EAX || reg->index == REG_GP_EBX
			|| reg->index == REG_GP_ECX || reg->index == REG_GP_EDX);

	be_emit_char('%');
	be_emit_char(reg->name[1]); /* get the basic name of the register */
	be_emit_char('l');
}

/**
 * Emit the name of the 8bit high register
 */
static void emit_8bit_register_high(const arch_register_t *reg)
{
	assert(reg->index == REG_GP_EAX || reg->index == REG_GP_EBX
			|| reg->index == REG_GP_ECX || reg->index == REG_GP_EDX);

	be_emit_char('%');
	be_emit_char(reg->name[1]); /* get the basic name of the register */
	be_emit_char('h');
}

static void emit_16bit_register(const arch_register_t *reg)
{
	be_emit_char('%');
	be_emit_string(reg->name + 1); /* skip the 'e' prefix of the 32bit names */
}

/**
 * emit a register, possible shortened by a mode
 *
 * @param reg   the register
 * @param mode  the mode of the register or NULL for full register
 */
static void emit_register(const arch_register_t *reg, const ir_mode *mode)
{
	if (mode != NULL) {
		int size = get_mode_size_bits(mode);
		switch (size) {
			case  8: emit_8bit_register(reg);  return;
			case 16: emit_16bit_register(reg); return;
		}
		assert(mode_is_float(mode) || size == 32);
	}

	be_emit_char('%');
	be_emit_string(reg->name);
}

static void ia32_emit_entity(ir_entity *entity, int no_pic_adjust)
{
	be_gas_emit_entity(entity);

	if (is_tls_entity(entity)) {
		if (!entity_has_definition(entity)) {
			be_emit_cstring("@INDNTPOFF");
		} else {
			be_emit_cstring("@NTPOFF");
		}
	}

	if (do_pic && !no_pic_adjust && get_entity_type(entity) != get_code_type()) {
		be_emit_char('-');
		be_emit_string(pic_base_label);
	}
}

static void emit_ia32_Immediate_no_prefix(const ir_node *node)
{
	const ia32_immediate_attr_t *attr = get_ia32_immediate_attr_const(node);

	ir_entity *const entity = attr->entity;
	if (entity != NULL) {
		ia32_emit_entity(entity, attr->no_pic_adjust);
		if (attr->offset != 0) {
			be_emit_irprintf("%+"PRId32, attr->offset);
		}
	} else {
		be_emit_irprintf("0x%"PRIX32, (uint32_t)attr->offset);
	}
}

static void emit_ia32_Immediate(const ir_node *node)
{
	be_emit_char('$');
	emit_ia32_Immediate_no_prefix(node);
}

static void ia32_emit_mode_suffix_mode(const ir_mode *mode)
{
	assert(mode_is_int(mode) || mode_is_reference(mode));
	switch (get_mode_size_bits(mode)) {
		case 8:  be_emit_char('b');     return;
		case 16: be_emit_char('w');     return;
		case 32: be_emit_char('l');     return;
		/* gas docu says q is the suffix but gcc, objdump and icc use ll
		 * apparently */
		case 64: be_emit_cstring("ll"); return;
	}
	panic("Cannot output mode_suffix for %+F", mode);
}

static void ia32_emit_x87_mode_suffix(ir_node const *const node)
{
	ir_mode *mode;

	/* we only need to emit the mode on address mode */
	if (get_ia32_op_type(node) == ia32_Normal)
		return;

	mode = get_ia32_ls_mode(node);
	assert(mode != NULL);

	if (mode_is_float(mode)) {
		switch (get_mode_size_bits(mode)) {
			case  32: be_emit_char('s'); return;
			case  64: be_emit_char('l'); return;
			/* long doubles have different sizes due to alignment on different
			 * platforms. */
			case  80:
			case  96:
			case 128: be_emit_char('t'); return;
		}
	} else {
		assert(mode_is_int(mode) || mode_is_reference(mode));
		switch (get_mode_size_bits(mode)) {
			case 16: be_emit_char('s');     return;
			case 32: be_emit_char('l');     return;
			/* gas docu says q is the suffix but gcc, objdump and icc use ll
			 * apparently */
			case 64: be_emit_cstring("ll"); return;
		}
	}
	panic("Cannot output mode_suffix for %+F", mode);
}

static char get_xmm_mode_suffix(ir_mode *mode)
{
	assert(mode_is_float(mode));
	switch (get_mode_size_bits(mode)) {
	case 32: return 's';
	case 64: return 'd';
	default: panic("Invalid XMM mode");
	}
}

static void ia32_emit_xmm_mode_suffix(ir_node const *const node)
{
	ir_mode *mode = get_ia32_ls_mode(node);
	assert(mode != NULL);
	be_emit_char(get_xmm_mode_suffix(mode));
}

/**
 * Returns the target block for a control flow node.
 */
static ir_node *get_cfop_target_block(const ir_node *irn)
{
	assert(get_irn_mode(irn) == mode_X);
	return (ir_node*)get_irn_link(irn);
}

/**
 * Emits the target label for a control flow node.
 */
static void ia32_emit_cfop_target(const ir_node *node)
{
	ir_node *block = get_cfop_target_block(node);
	be_gas_emit_block_name(block);
}

void x86_emit_condition_code(x86_condition_code_t cc)
{
	switch (cc) {
	case x86_cc_overflow:      be_emit_cstring("o");  return;
	case x86_cc_not_overflow:  be_emit_cstring("no"); return;
	case x86_cc_float_below:
	case x86_cc_float_unordered_below:
	case x86_cc_below:         be_emit_cstring("b");  return;
	case x86_cc_float_above_equal:
	case x86_cc_float_unordered_above_equal:
	case x86_cc_above_equal:   be_emit_cstring("ae"); return;
	case x86_cc_float_equal:
	case x86_cc_equal:         be_emit_cstring("e");  return;
	case x86_cc_float_not_equal:
	case x86_cc_not_equal:     be_emit_cstring("ne"); return;
	case x86_cc_float_below_equal:
	case x86_cc_float_unordered_below_equal:
	case x86_cc_below_equal:   be_emit_cstring("be"); return;
	case x86_cc_float_above:
	case x86_cc_float_unordered_above:
	case x86_cc_above:         be_emit_cstring("a");  return;
	case x86_cc_sign:          be_emit_cstring("s");  return;
	case x86_cc_not_sign:      be_emit_cstring("ns"); return;
	case x86_cc_parity:        be_emit_cstring("p");  return;
	case x86_cc_not_parity:    be_emit_cstring("np"); return;
	case x86_cc_less:          be_emit_cstring("l");  return;
	case x86_cc_greater_equal: be_emit_cstring("ge"); return;
	case x86_cc_less_equal:    be_emit_cstring("le"); return;
	case x86_cc_greater:       be_emit_cstring("g");  return;
	case x86_cc_float_parity_cases:
	case x86_cc_additional_float_cases:
		break;
	}
	panic("Invalid ia32 condition code");
}

typedef enum ia32_emit_mod_t {
	EMIT_NONE         = 0,
	EMIT_RESPECT_LS   = 1U << 0,
	EMIT_ALTERNATE_AM = 1U << 1,
	EMIT_LONG         = 1U << 2,
	EMIT_HIGH_REG     = 1U << 3,
	EMIT_LOW_REG      = 1U << 4,
	EMIT_16BIT_REG    = 1U << 5,
	EMIT_SHIFT_COMMA  = 1U << 6,
} ia32_emit_mod_t;
ENUM_BITSET(ia32_emit_mod_t)

/**
 * Emits address mode.
 */
static void ia32_emit_am(ir_node const *const node)
{
	ir_entity *ent       = get_ia32_am_ent(node);
	int32_t    offs      = get_ia32_am_offs_int(node);
	ir_node   *base      = get_irn_n(node, n_ia32_base);
	int        has_base  = !is_ia32_NoReg_GP(base);
	ir_node   *idx       = get_irn_n(node, n_ia32_index);
	int        has_index = !is_ia32_NoReg_GP(idx);

	/* just to be sure... */
	assert(!is_ia32_use_frame(node) || get_ia32_frame_ent(node) != NULL);

	if (get_ia32_am_tls_segment(node))
		be_emit_cstring("%gs:");

	/* emit offset */
	if (ent != NULL) {
		const ia32_attr_t *attr = get_ia32_attr_const(node);
		ia32_emit_entity(ent, attr->data.am_sc_no_pic_adjust);
	}

	/* also handle special case if nothing is set */
	if (offs != 0 || (ent == NULL && !has_base && !has_index)) {
		if (ent != NULL) {
			be_emit_irprintf("%+"PRId32, offs);
		} else {
			be_emit_irprintf("%"PRId32, offs);
		}
	}

	if (has_base || has_index) {
		be_emit_char('(');

		/* emit base */
		if (has_base) {
			const arch_register_t *reg = arch_get_irn_register_in(node, n_ia32_base);
			emit_register(reg, NULL);
		}

		/* emit index + scale */
		if (has_index) {
			const arch_register_t *reg = arch_get_irn_register_in(node, n_ia32_index);
			int scale;
			be_emit_char(',');
			emit_register(reg, NULL);

			scale = get_ia32_am_scale(node);
			if (scale > 0) {
				be_emit_irprintf(",%d", 1 << scale);
			}
		}
		be_emit_char(')');
	}
}

static x86_condition_code_t determine_final_cc(ir_node const *node, int flags_pos, x86_condition_code_t cc);

void ia32_emitf(ir_node const *const node, char const *fmt, ...)
{
	va_list ap;
	va_start(ap, fmt);

	be_emit_char('\t');
	for (;;) {
		const char      *start = fmt;
		ia32_emit_mod_t  mod   = EMIT_NONE;

		while (*fmt != '%' && *fmt != '\n' && *fmt != '\0')
			++fmt;
		if (fmt != start) {
			be_emit_string_len(start, fmt - start);
		}

		if (*fmt == '\n') {
			be_emit_char('\n');
			be_emit_write_line();
			be_emit_char('\t');
			++fmt;
			if (*fmt == '\0')
				break;
			continue;
		}

		if (*fmt == '\0')
			break;

		++fmt;
		for (;;) {
			switch (*fmt) {
			case '*': mod |= EMIT_ALTERNATE_AM; break;
			case '#': mod |= EMIT_RESPECT_LS;   break;
			case 'l': mod |= EMIT_LONG;         break;
			case '>': mod |= EMIT_HIGH_REG;     break;
			case '<': mod |= EMIT_LOW_REG;      break;
			case '^': mod |= EMIT_16BIT_REG;    break;
			case ',': mod |= EMIT_SHIFT_COMMA;  break;
			default:
				goto end_of_mods;
			}
			++fmt;
		}
end_of_mods:

		switch (*fmt++) {
			arch_register_t const *reg;
			ir_node         const *imm;

			case '%':
				be_emit_char('%');
				break;

			case 'A': {
				switch (*fmt++) {
					case 'F':
						if (get_ia32_op_type(node) == ia32_Normal) {
							ia32_x87_attr_t const *const attr = get_ia32_x87_attr_const(node);
							char            const *const fmt  = attr->res_in_reg ? "%%st, %%%s" : "%%%s, %%st";
							be_emit_irprintf(fmt, attr->reg->name);
							break;
						} else {
							goto emit_AM;
						}

emit_AM:
					case 'M':
						if (mod & EMIT_ALTERNATE_AM)
							be_emit_char('*');
						ia32_emit_am(node);
						break;

					case 'R':
						reg = va_arg(ap, const arch_register_t*);
						if (get_ia32_op_type(node) == ia32_Normal) {
							goto emit_R;
						} else {
							goto emit_AM;
						}

					case 'S':
						if (get_ia32_op_type(node) == ia32_Normal) {
							goto emit_S;
						} else {
							++fmt;
							goto emit_AM;
						}

					default: goto unknown;
				}
				break;
			}

			case 'B':
				imm = get_irn_n(node, n_ia32_binary_right);
				if (is_ia32_Immediate(imm)) {
					emit_ia32_Immediate(imm);
					be_emit_cstring(", ");
					if (get_ia32_op_type(node) == ia32_Normal) {
						goto destination_operand;
					} else {
						ia32_emit_am(node);
					}
				} else {
					if (get_ia32_op_type(node) == ia32_Normal) {
						reg = arch_get_irn_register_in(node, n_ia32_binary_right);
						emit_register(reg, get_ia32_ls_mode(node));
					} else {
						ia32_emit_am(node);
					}
					be_emit_cstring(", ");
destination_operand:
					reg = arch_get_irn_register_in(node, n_ia32_binary_left);
					emit_register(reg, get_ia32_ls_mode(node));
				}
				break;

			case 'D':
				if (*fmt < '0' || '9' < *fmt)
					goto unknown;
				reg = arch_get_irn_register_out(node, *fmt++ - '0');
				goto emit_R;

			case 'F':
				if (*fmt == 'M') {
					ia32_emit_x87_mode_suffix(node);
				} else if (*fmt == 'P') {
					ia32_x87_attr_t const *const attr = get_ia32_x87_attr_const(node);
					if (attr->pop)
						be_emit_char('p');
				} else if (*fmt == 'R') {
					/* NOTE: Work around a gas quirk for non-commutative operations if the
					 * destination register is not %st0.  In this case r/non-r is swapped.
					 * %st0 = %st0 - %st1 -> fsub  %st1, %st0 (as expected)
					 * %st0 = %st1 - %st0 -> fsubr %st1, %st0 (as expected)
					 * %st1 = %st0 - %st1 -> fsub  %st0, %st1 (expected: fsubr)
					 * %st1 = %st1 - %st0 -> fsubr %st0, %st1 (expected: fsub)
					 * In fact this corresponds to the encoding of the instruction:
					 * - The r suffix selects whether %st0 is on the left (no r) or on the
					 *   right (r) side of the executed operation.
					 * - The placement of %st0 selects whether the result is written to
					 *   %st0 (right) or the other register (left).
					 * This means that it is sufficient to test whether the operands are
					 * permuted.  In particular it is not necessary to consider wether the
					 * result is to be placed into the explicit register operand. */
					if (get_ia32_x87_attr_const(node)->attr.data.ins_permuted)
						be_emit_char('r');
				} else if (*fmt == 'X') {
					ia32_emit_xmm_mode_suffix(node);
				} else if (*fmt == '0') {
					be_emit_char('%');
					be_emit_string(get_ia32_x87_attr_const(node)->reg->name);
				} else {
					goto unknown;
				}
				++fmt;
				break;

			case 'I':
				imm = node;
emit_I:
				if (mod & EMIT_SHIFT_COMMA) {
					const ia32_immediate_attr_t *attr
						= get_ia32_immediate_attr_const(imm);
					if (attr->entity == NULL && attr->offset == 1)
						break;
				}
				if (!(mod & EMIT_ALTERNATE_AM))
					be_emit_char('$');
				emit_ia32_Immediate_no_prefix(imm);
				if (mod & EMIT_SHIFT_COMMA) {
					be_emit_char(',');
				}
				break;

			case 'L':
				ia32_emit_cfop_target(node);
				break;

			case 'M': {
				ir_mode *mode = get_ia32_ls_mode(node);
				if (!mode)
					mode = ia32_mode_gp;
				if (mod & EMIT_RESPECT_LS) {
					if (get_mode_size_bits(mode) == 32)
						break;
					be_emit_char(mode_is_signed(mode) ? 's' : 'z');
				}
				ia32_emit_mode_suffix_mode(mode);
				break;
			}

			case 'P': {
				x86_condition_code_t cc;
				if (*fmt == 'X') {
					++fmt;
					cc = (x86_condition_code_t)va_arg(ap, int);
				} else if ('0' <= *fmt && *fmt <= '9') {
					cc = get_ia32_condcode(node);
					cc = determine_final_cc(node, *fmt - '0', cc);
					++fmt;
				} else {
					goto unknown;
				}
				x86_emit_condition_code(cc);
				break;
			}

			case 'R':
				reg = va_arg(ap, const arch_register_t*);
emit_R:
				if (mod & EMIT_ALTERNATE_AM)
					be_emit_char('*');
				if (mod & EMIT_HIGH_REG) {
					emit_8bit_register_high(reg);
				} else if (mod & EMIT_LOW_REG) {
					emit_8bit_register(reg);
				} else if (mod & EMIT_16BIT_REG) {
					emit_16bit_register(reg);
				} else {
					emit_register(reg, mod & EMIT_RESPECT_LS ? get_ia32_ls_mode(node) : NULL);
				}
				if (mod & EMIT_SHIFT_COMMA) {
					be_emit_char(',');
				}
				break;

emit_S:
			case 'S': {
				unsigned pos;

				if (*fmt < '0' || '9' < *fmt)
					goto unknown;

				pos = *fmt++ - '0';
				imm = get_irn_n(node, pos);
				if (is_ia32_Immediate(imm)) {
					goto emit_I;
				} else {
					reg = arch_get_irn_register_in(node, pos);
					goto emit_R;
				}
			}

			case 's': {
				const char *str = va_arg(ap, const char*);
				be_emit_string(str);
				break;
			}

			case 'u':
				if (mod & EMIT_LONG) {
					unsigned long num = va_arg(ap, unsigned long);
					be_emit_irprintf("%lu", num);
				} else {
					unsigned num = va_arg(ap, unsigned);
					be_emit_irprintf("%u", num);
				}
				break;

			case 'd':
				if (mod & EMIT_LONG) {
					long num = va_arg(ap, long);
					be_emit_irprintf("%ld", num);
				} else {
					int num = va_arg(ap, int);
					be_emit_irprintf("%d", num);
				}
				break;

			default:
unknown:
				panic("unknown format conversion");
		}
	}

	be_emit_finish_line_gas(node);
	va_end(ap);
}

static void emit_ia32_IMul(const ir_node *node)
{
	ir_node               *left    = get_irn_n(node, n_ia32_IMul_left);
	const arch_register_t *out_reg = arch_get_irn_register_out(node, pn_ia32_IMul_res);

	/* do we need the 3-address form? */
	if (is_ia32_NoReg_GP(left) ||
			arch_get_irn_register_in(node, n_ia32_IMul_left) != out_reg) {
		ia32_emitf(node, "imul%M %#S4, %#AS3, %#D0");
	} else {
		ia32_emitf(node, "imul%M %#AS4, %#S3");
	}
}

/**
 * walks up a tree of copies/perms/spills/reloads to find the original value
 * that is moved around
 */
static ir_node *find_original_value(ir_node *node)
{
	if (irn_visited(node))
		return NULL;

	mark_irn_visited(node);
	if (be_is_Copy(node)) {
		return find_original_value(be_get_Copy_op(node));
	} else if (be_is_CopyKeep(node)) {
		return find_original_value(be_get_CopyKeep_op(node));
	} else if (is_Proj(node)) {
		ir_node *pred = get_Proj_pred(node);
		if (be_is_Perm(pred)) {
			return find_original_value(get_irn_n(pred, get_Proj_proj(node)));
		} else if (be_is_MemPerm(pred)) {
			return find_original_value(get_irn_n(pred, get_Proj_proj(node) + 1));
		} else if (is_ia32_Load(pred)) {
			return find_original_value(get_irn_n(pred, n_ia32_Load_mem));
		} else if (is_ia32_Store(pred)) {
			return find_original_value(get_irn_n(pred, n_ia32_Store_val));
		} else {
			return node;
		}
	} else if (is_Phi(node)) {
		foreach_irn_in(node, i, in) {
			ir_node *res = find_original_value(in);
			if (res != NULL)
				return res;
		}
		return NULL;
	} else {
		return node;
	}
}

static x86_condition_code_t determine_final_cc(const ir_node *node,
                                               int flags_pos,
                                               x86_condition_code_t cc)
{
	ir_node           *flags = get_irn_n(node, flags_pos);
	const ia32_attr_t *flags_attr;
	flags = skip_Proj(flags);

	/* Permuted operands of a test instruction do not change the result. */
	if (is_ia32_Test(flags)) {
		return cc;
	}

	if (is_ia32_Sahf(flags)) {
		ir_node *cmp = get_irn_n(flags, n_ia32_Sahf_val);
		if (!(is_ia32_FucomFnstsw(cmp) || is_ia32_FucomppFnstsw(cmp) || is_ia32_FtstFnstsw(cmp))) {
			ir_graph *irg = get_irn_irg(node);
			inc_irg_visited(irg);
			cmp = find_original_value(cmp);
			assert(cmp != NULL);
			assert(is_ia32_FucomFnstsw(cmp) || is_ia32_FucomppFnstsw(cmp) || is_ia32_FtstFnstsw(cmp));
		}

		flags_attr = get_ia32_attr_const(cmp);
	} else {
		flags_attr = get_ia32_attr_const(flags);
	}

	if (flags_attr->data.ins_permuted)
		cc = x86_invert_condition_code(cc);
	return cc;
}

/**
 * Emits an exception label for a given node.
 */
static void ia32_emit_exc_label(const ir_node *node)
{
	be_emit_string(be_gas_insn_label_prefix());
	be_emit_irprintf("%lu", get_ia32_exc_label_id(node));
}

static bool fallthrough_possible(const ir_node *block, const ir_node *target)
{
	return get_prev_block_sched(target) == block;
}

/**
 * Emits the jump sequence for a conditional jump (cmp + jmp_true + jmp_false)
 */
static void emit_ia32_Jcc(const ir_node *node)
{
	x86_condition_code_t cc = get_ia32_condcode(node);
	cc = determine_final_cc(node, 0, cc);

	/* get both Projs */
	ir_node const *proj_true   = be_get_Proj_for_pn(node, pn_ia32_Jcc_true);
	ir_node const *target_true = get_cfop_target_block(proj_true);
	ir_node const *proj_false  = be_get_Proj_for_pn(node, pn_ia32_Jcc_false);
	ir_node const *block       = get_nodes_block(node);
	if (fallthrough_possible(block, target_true)) {
		/* exchange both proj's so the second one can be omitted */
		const ir_node *t = proj_true;

		proj_true  = proj_false;
		proj_false = t;
		cc         = x86_negate_condition_code(cc);
	}
	const ir_node *target_false = get_cfop_target_block(proj_false);
	bool           fallthrough  = fallthrough_possible(block, target_false);
	/* if we can't have a fallthrough anyway, put the more likely case first */
	if (!fallthrough) {
		/* We would need execfreq for the concrete edge, but don't have it
		 * available here, so we use the block execfreq :-( */
		double freq_true  = get_block_execfreq(target_true);
		double freq_false = get_block_execfreq(target_false);
		if (freq_false > freq_true) {
			const ir_node *t = proj_true;
			proj_true  = proj_false;
			proj_false = t;
			cc         = x86_negate_condition_code(cc);
		}
	}

	bool need_parity_label = false;
	if (cc & x86_cc_float_parity_cases) {
		/* Some floating point comparisons require a test of the parity flag,
		 * which indicates that the result is unordered */
		if (cc & x86_cc_negated) {
			ia32_emitf(proj_true, "jp %L");
		} else {
			/* we need a local label if the false proj is a fallthrough
			 * as the falseblock might have no label emitted then */
			if (fallthrough) {
				need_parity_label = true;
				ia32_emitf(proj_false, "jp 1f");
			} else {
				ia32_emitf(proj_false, "jp %L");
			}
		}
	}
	ia32_emitf(proj_true, "j%PX %L", (int)cc);
	if (need_parity_label) {
		be_emit_cstring("1:\n");
		be_emit_write_line();
	}

	/* the second Proj might be a fallthrough */
	if (fallthrough) {
		if (be_options.verbose_asm)
			ia32_emitf(proj_false, "/* fallthrough to %L */");
	} else {
		ia32_emitf(proj_false, "jmp %L");
	}
}

/**
 * Emits an ia32 Setcc. This is mostly easy but some floating point compares
 * are tricky.
 */
static void emit_ia32_Setcc(const ir_node *node)
{
	const arch_register_t *dreg = arch_get_irn_register_out(node, pn_ia32_Setcc_res);

	x86_condition_code_t cc = get_ia32_condcode(node);
	cc = determine_final_cc(node, n_ia32_Setcc_eflags, cc);
	if (cc & x86_cc_float_parity_cases) {
		if (cc & x86_cc_negated) {
			ia32_emitf(node, "set%PX %<R", (int)cc, dreg);
			ia32_emitf(node, "setp %>R", dreg);
			ia32_emitf(node, "orb %>R, %<R", dreg, dreg);
		} else {
			ia32_emitf(node, "set%PX %<R", (int)cc, dreg);
			ia32_emitf(node, "setnp %>R", dreg);
			ia32_emitf(node, "andb %>R, %<R", dreg, dreg);
		}
	} else {
		ia32_emitf(node, "set%PX %#R", (int)cc, dreg);
	}
}

static void emit_ia32_CMovcc(const ir_node *node)
{
	const ia32_attr_t     *attr = get_ia32_attr_const(node);
	const arch_register_t *out  = arch_get_irn_register_out(node, pn_ia32_res);
	x86_condition_code_t   cc   = get_ia32_condcode(node);
	const arch_register_t *in_true;
	const arch_register_t *in_false;

	cc = determine_final_cc(node, n_ia32_CMovcc_eflags, cc);
	/* although you can't set ins_permuted in the constructor it might still
	 * be set by memory operand folding
	 * Permuting inputs of a cmov means the condition is negated!
	 */
	if (attr->data.ins_permuted)
		cc = x86_negate_condition_code(cc);

	in_true  = arch_get_irn_register(get_irn_n(node, n_ia32_CMovcc_val_true));
	in_false = arch_get_irn_register(get_irn_n(node, n_ia32_CMovcc_val_false));

	/* should be same constraint fullfilled? */
	if (out == in_false) {
		/* yes -> nothing to do */
	} else if (out == in_true) {
		const arch_register_t *tmp;

		assert(get_ia32_op_type(node) == ia32_Normal);

		cc = x86_negate_condition_code(cc);

		tmp      = in_true;
		in_true  = in_false;
		in_false = tmp;
	} else {
		/* we need a mov */
		ia32_emitf(node, "movl %R, %R", in_false, out);
	}