/compile.c

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/**********************************************************************

  compile.c - ruby node tree -> VM instruction sequence

  $Author$
  created at: 04/01/01 03:42:15 JST

  Copyright (C) 2004-2007 Koichi Sasada

**********************************************************************/

#include "ruby/ruby.h"
#include "internal.h"
#include <math.h>

#define USE_INSN_STACK_INCREASE 1
#include "vm_core.h"
#include "iseq.h"
#include "insns.inc"
#include "insns_info.inc"

#define FIXNUM_INC(n, i) ((n)+(INT2FIX(i)&~FIXNUM_FLAG))
#define FIXNUM_OR(n, i) ((n)|INT2FIX(i))

typedef struct iseq_link_element {
    enum {
	ISEQ_ELEMENT_NONE,
	ISEQ_ELEMENT_LABEL,
	ISEQ_ELEMENT_INSN,
	ISEQ_ELEMENT_ADJUST
    } type;
    struct iseq_link_element *next;
    struct iseq_link_element *prev;
} LINK_ELEMENT;

typedef struct iseq_link_anchor {
    LINK_ELEMENT anchor;
    LINK_ELEMENT *last;
} LINK_ANCHOR;

typedef struct iseq_label_data {
    LINK_ELEMENT link;
    int label_no;
    int position;
    int sc_state;
    int set;
    int sp;
} LABEL;

typedef struct iseq_insn_data {
    LINK_ELEMENT link;
    enum ruby_vminsn_type insn_id;
    unsigned int line_no;
    int operand_size;
    int sc_state;
    VALUE *operands;
} INSN;

typedef struct iseq_adjust_data {
    LINK_ELEMENT link;
    LABEL *label;
    int line_no;
} ADJUST;

struct ensure_range {
    LABEL *begin;
    LABEL *end;
    struct ensure_range *next;
};

struct iseq_compile_data_ensure_node_stack {
    NODE *ensure_node;
    struct iseq_compile_data_ensure_node_stack *prev;
    struct ensure_range *erange;
};

/**
 * debug function(macro) interface depend on CPDEBUG
 * if it is less than 0, runtime option is in effect.
 *
 * debug level:
 *  0: no debug output
 *  1: show node type
 *  2: show node important parameters
 *  ...
 *  5: show other parameters
 * 10: show every AST array
 */

#ifndef CPDEBUG
#define CPDEBUG 0
#endif

#if CPDEBUG >= 0
#define compile_debug CPDEBUG
#else
#define compile_debug iseq->compile_data->option->debug_level
#endif

#if CPDEBUG

#define compile_debug_print_indent(level) \
    ruby_debug_print_indent((level), compile_debug, gl_node_level * 2)

#define debugp(header, value) (void) \
  (compile_debug_print_indent(1) && \
   ruby_debug_print_value(1, compile_debug, (header), (value)))

#define debugi(header, id)  (void) \
  (compile_debug_print_indent(1) && \
   ruby_debug_print_id(1, compile_debug, (header), (id)))

#define debugp_param(header, value)  (void) \
  (compile_debug_print_indent(1) && \
   ruby_debug_print_value(1, compile_debug, (header), (value)))

#define debugp_verbose(header, value)  (void) \
  (compile_debug_print_indent(2) && \
   ruby_debug_print_value(2, compile_debug, (header), (value)))

#define debugp_verbose_node(header, value)  (void) \
  (compile_debug_print_indent(10) && \
   ruby_debug_print_value(10, compile_debug, (header), (value)))

#define debug_node_start(node)  ((void) \
  (compile_debug_print_indent(1) && \
   (ruby_debug_print_node(1, CPDEBUG, "", (NODE *)(node)), gl_node_level)), \
   gl_node_level++)

#define debug_node_end()  gl_node_level --

#else

static inline ID
r_id(ID id)
{
    return id;
}

static inline VALUE
r_value(VALUE value)
{
    return value;
}

#define debugi(header, id)                 r_id(id)
#define debugp(header, value)              r_value(value)
#define debugp_verbose(header, value)      r_value(value)
#define debugp_verbose_node(header, value) r_value(value)
#define debugp_param(header, value)        r_value(value)
#define debug_node_start(node)             ((void)0)
#define debug_node_end()                   ((void)0)
#endif

#if CPDEBUG > 1 || CPDEBUG < 0
#define debugs if (compile_debug_print_indent(1)) ruby_debug_printf
#define debug_compile(msg, v) ((void)(compile_debug_print_indent(1) && fputs((msg), stderr)), (v))
#else
#define debugs                             if(0)printf
#define debug_compile(msg, v) (v)
#endif


/* create new label */
#define NEW_LABEL(l) new_label_body(iseq, (l))

#define iseq_path(iseq) \
  (((rb_iseq_t*)DATA_PTR(iseq))->location.path)

#define iseq_absolute_path(iseq) \
  (((rb_iseq_t*)DATA_PTR(iseq))->location.absolute_path)

#define NEW_ISEQVAL(node, name, type, line_no)       \
  new_child_iseq(iseq, (node), (name), 0, (type), (line_no))

#define NEW_CHILD_ISEQVAL(node, name, type, line_no)       \
  new_child_iseq(iseq, (node), (name), iseq->self, (type), (line_no))

/* add instructions */
#define ADD_SEQ(seq1, seq2) \
  APPEND_LIST((seq1), (seq2))

/* add an instruction */
#define ADD_INSN(seq, line, insn) \
  ADD_ELEM((seq), (LINK_ELEMENT *) new_insn_body(iseq, (line), BIN(insn), 0))

/* add an instruction with some operands (1, 2, 3, 5) */
#define ADD_INSN1(seq, line, insn, op1) \
  ADD_ELEM((seq), (LINK_ELEMENT *) \
           new_insn_body(iseq, (line), BIN(insn), 1, (VALUE)(op1)))

/* add an instruction with label operand (alias of ADD_INSN1) */
#define ADD_INSNL(seq, line, insn, label) ADD_INSN1(seq, line, insn, label)

#define ADD_INSN2(seq, line, insn, op1, op2) \
  ADD_ELEM((seq), (LINK_ELEMENT *) \
           new_insn_body(iseq, (line), BIN(insn), 2, (VALUE)(op1), (VALUE)(op2)))

#define ADD_INSN3(seq, line, insn, op1, op2, op3) \
  ADD_ELEM((seq), (LINK_ELEMENT *) \
           new_insn_body(iseq, (line), BIN(insn), 3, (VALUE)(op1), (VALUE)(op2), (VALUE)(op3)))

/* Specific Insn factory */
#define ADD_SEND(seq, line, id, argc) \
  ADD_SEND_R((seq), (line), (id), (argc), (VALUE)Qfalse, (VALUE)INT2FIX(0))

#define ADD_CALL_RECEIVER(seq, line) \
  ADD_INSN((seq), (line), putself)

#define ADD_CALL(seq, line, id, argc) \
  ADD_SEND_R((seq), (line), (id), (argc), (VALUE)Qfalse, (VALUE)INT2FIX(VM_CALL_FCALL))

#define ADD_CALL_WITH_BLOCK(seq, line, id, argc, block) \
  ADD_SEND_R((seq), (line), (id), (argc), (block), (VALUE)INT2FIX(VM_CALL_FCALL))

#define ADD_SEND_R(seq, line, id, argc, block, flag) \
  ADD_ELEM((seq), (LINK_ELEMENT *) \
           new_insn_send(iseq, (line), \
                         (VALUE)(id), (VALUE)(argc), (VALUE)(block), (VALUE)(flag)))

#define ADD_TRACE(seq, line, event) \
  do { \
      if ((event) == RUBY_EVENT_LINE && iseq->coverage && \
	  (line) != iseq->compile_data->last_coverable_line) { \
	  RARRAY_ASET(iseq->coverage, (line) - 1, INT2FIX(0)); \
	  iseq->compile_data->last_coverable_line = (line); \
	  ADD_INSN1((seq), (line), trace, INT2FIX(RUBY_EVENT_COVERAGE)); \
      } \
      if (iseq->compile_data->option->trace_instruction) { \
	  ADD_INSN1((seq), (line), trace, INT2FIX(event)); \
      } \
  } while (0)

/* add label */
#define ADD_LABEL(seq, label) \
  ADD_ELEM((seq), (LINK_ELEMENT *) (label))

#define APPEND_LABEL(seq, before, label) \
  APPEND_ELEM((seq), (before), (LINK_ELEMENT *) (label))

#define ADD_ADJUST(seq, line, label) \
  ADD_ELEM((seq), (LINK_ELEMENT *) new_adjust_body(iseq, (label), (line)))

#define ADD_ADJUST_RESTORE(seq, label) \
  ADD_ELEM((seq), (LINK_ELEMENT *) new_adjust_body(iseq, (label), -1))

#define ADD_CATCH_ENTRY(type, ls, le, iseqv, lc)		\
    (rb_ary_push(iseq->compile_data->catch_table_ary,		\
		 rb_ary_new3(5, (type),				\
			     (VALUE)(ls) | 1, (VALUE)(le) | 1,	\
			     (VALUE)(iseqv), (VALUE)(lc) | 1)))

/* compile node */
#define COMPILE(anchor, desc, node) \
  (debug_compile("== " desc "\n", \
                 iseq_compile_each(iseq, (anchor), (node), 0)))

/* compile node, this node's value will be popped */
#define COMPILE_POPED(anchor, desc, node)    \
  (debug_compile("== " desc "\n", \
                 iseq_compile_each(iseq, (anchor), (node), 1)))

/* compile node, which is popped when 'poped' is true */
#define COMPILE_(anchor, desc, node, poped)  \
  (debug_compile("== " desc "\n", \
                 iseq_compile_each(iseq, (anchor), (node), (poped))))

#define OPERAND_AT(insn, idx) \
  (((INSN*)(insn))->operands[(idx)])

#define INSN_OF(insn) \
  (((INSN*)(insn))->insn_id)

/* error */
#define COMPILE_ERROR(strs)                        \
{                                                  \
  VALUE tmp = GET_THREAD()->errinfo;               \
  if (compile_debug) rb_compile_bug strs;          \
  GET_THREAD()->errinfo = iseq->compile_data->err_info;  \
  rb_compile_error strs;                           \
  OBJ_WRITE(iseq->self, &iseq->compile_data->err_info, GET_THREAD()->errinfo); \
  GET_THREAD()->errinfo = tmp;                     \
  ret = 0;                                         \
  break;                                           \
}

#define ERROR_ARGS ruby_sourcefile, nd_line(node),


#define COMPILE_OK 1
#define COMPILE_NG 0


/* leave name uninitialized so that compiler warn if INIT_ANCHOR is
 * missing */
#define DECL_ANCHOR(name) \
  LINK_ANCHOR *name, name##_body__ = {{0,},}
#define INIT_ANCHOR(name) \
  (name##_body__.last = &name##_body__.anchor, name = &name##_body__)

#define hide_obj(obj) do {OBJ_FREEZE(obj); RBASIC_CLEAR_CLASS(obj);} while (0)

#include "optinsn.inc"
#if OPT_INSTRUCTIONS_UNIFICATION
#include "optunifs.inc"
#endif

/* for debug */
#if CPDEBUG < 0
#define ISEQ_ARG iseq,
#define ISEQ_ARG_DECLARE rb_iseq_t *iseq,
#else
#define ISEQ_ARG
#define ISEQ_ARG_DECLARE
#endif

#if CPDEBUG
#define gl_node_level iseq->compile_data->node_level
#if 0
static void debug_list(ISEQ_ARG_DECLARE LINK_ANCHOR *anchor);
#endif
#endif

static void dump_disasm_list(LINK_ELEMENT *elem);

static int insn_data_length(INSN *iobj);
static int insn_data_line_no(INSN *iobj);
static int calc_sp_depth(int depth, INSN *iobj);

static INSN *new_insn_body(rb_iseq_t *iseq, int line_no, int insn_id, int argc, ...);
static LABEL *new_label_body(rb_iseq_t *iseq, long line);
static ADJUST *new_adjust_body(rb_iseq_t *iseq, LABEL *label, int line);

static int iseq_compile_each(rb_iseq_t *iseq, LINK_ANCHOR *anchor, NODE * n, int);
static int iseq_setup(rb_iseq_t *iseq, LINK_ANCHOR *anchor);
static int iseq_optimize(rb_iseq_t *iseq, LINK_ANCHOR *anchor);
static int iseq_insns_unification(rb_iseq_t *iseq, LINK_ANCHOR *anchor);

static int iseq_set_local_table(rb_iseq_t *iseq, ID *tbl);
static int iseq_set_exception_local_table(rb_iseq_t *iseq);
static int iseq_set_arguments(rb_iseq_t *iseq, LINK_ANCHOR *anchor, NODE * node);

static int iseq_set_sequence_stackcaching(rb_iseq_t *iseq, LINK_ANCHOR *anchor);
static int iseq_set_sequence(rb_iseq_t *iseq, LINK_ANCHOR *anchor);
static int iseq_set_exception_table(rb_iseq_t *iseq);
static int iseq_set_optargs_table(rb_iseq_t *iseq);

/*
 * To make Array to LinkedList, use link_anchor
 */

static void
verify_list(ISEQ_ARG_DECLARE const char *info, LINK_ANCHOR *anchor)
{
#if CPDEBUG
    int flag = 0;
    LINK_ELEMENT *list, *plist;

    if (!compile_debug) return;

    list = anchor->anchor.next;
    plist = &anchor->anchor;
    while (list) {
	if (plist != list->prev) {
	    flag += 1;
	}
	plist = list;
	list = list->next;
    }

    if (anchor->last != plist && anchor->last != 0) {
	flag |= 0x70000;
    }

    if (flag != 0) {
	rb_bug("list verify error: %08x (%s)", flag, info);
    }
#endif
}
#if CPDEBUG < 0
#define verify_list(info, anchor) verify_list(iseq, (info), (anchor))
#endif

/*
 * elem1, elem2 => elem1, elem2, elem
 */
static void
ADD_ELEM(ISEQ_ARG_DECLARE LINK_ANCHOR *anchor, LINK_ELEMENT *elem)
{
    elem->prev = anchor->last;
    anchor->last->next = elem;
    anchor->last = elem;
    verify_list("add", anchor);
}

/*
 * elem1, before, elem2 => elem1, before, elem, elem2
 */
static void
APPEND_ELEM(ISEQ_ARG_DECLARE LINK_ANCHOR *anchor, LINK_ELEMENT *before, LINK_ELEMENT *elem)
{
    elem->prev = before;
    elem->next = before->next;
    elem->next->prev = elem;
    before->next = elem;
    if (before == anchor->last) anchor->last = elem;
    verify_list("add", anchor);
}
#if CPDEBUG < 0
#define ADD_ELEM(anchor, elem) ADD_ELEM(iseq, (anchor), (elem))
#define APPEND_ELEM(anchor, before, elem) ADD_ELEM(iseq, (anchor), (before), (elem))
#endif

static int
iseq_add_mark_object(rb_iseq_t *iseq, VALUE v)
{
    if (!SPECIAL_CONST_P(v)) {
	rb_iseq_add_mark_object(iseq, v);
    }
    return COMPILE_OK;
}

#define ruby_sourcefile		RSTRING_PTR(iseq->location.path)

static int
iseq_add_mark_object_compile_time(rb_iseq_t *iseq, VALUE v)
{
    if (!SPECIAL_CONST_P(v)) {
	rb_ary_push(iseq->compile_data->mark_ary, v);
    }
    return COMPILE_OK;
}

static int
validate_label(st_data_t name, st_data_t label, st_data_t arg)
{
    rb_iseq_t *iseq = (rb_iseq_t *)arg;
    LABEL *lobj = (LABEL *)label;
    if (!lobj->link.next) {
	do {
	    int ret;
	    COMPILE_ERROR((ruby_sourcefile, lobj->position,
			   "%s: undefined label", rb_id2name((ID)name)));
	    if (ret) break;
	} while (0);
    }
    return ST_CONTINUE;
}

static void
validate_labels(rb_iseq_t *iseq, st_table *labels_table)
{
    st_foreach(labels_table, validate_label, (st_data_t)iseq);
    if (!NIL_P(iseq->compile_data->err_info)) {
	rb_exc_raise(iseq->compile_data->err_info);
    }
}

VALUE
rb_iseq_compile_node(VALUE self, NODE *node)
{
    DECL_ANCHOR(ret);
    rb_iseq_t *iseq;
    INIT_ANCHOR(ret);
    GetISeqPtr(self, iseq);

    if (node == 0) {
	COMPILE(ret, "nil", node);
	iseq_set_local_table(iseq, 0);
    }
    else if (nd_type(node) == NODE_SCOPE) {
	/* iseq type of top, method, class, block */
	iseq_set_local_table(iseq, node->nd_tbl);
	iseq_set_arguments(iseq, ret, node->nd_args);

	switch (iseq->type) {
	  case ISEQ_TYPE_BLOCK:
	    {
		LABEL *start = iseq->compile_data->start_label = NEW_LABEL(0);
		LABEL *end = iseq->compile_data->end_label = NEW_LABEL(0);

		ADD_LABEL(ret, start);
		ADD_TRACE(ret, FIX2INT(iseq->location.first_lineno), RUBY_EVENT_B_CALL);
		COMPILE(ret, "block body", node->nd_body);
		ADD_LABEL(ret, end);
		ADD_TRACE(ret, nd_line(node), RUBY_EVENT_B_RETURN);

		/* wide range catch handler must put at last */
		ADD_CATCH_ENTRY(CATCH_TYPE_REDO, start, end, 0, start);
		ADD_CATCH_ENTRY(CATCH_TYPE_NEXT, start, end, 0, end);
		break;
	    }
	  case ISEQ_TYPE_CLASS:
	    {
		ADD_TRACE(ret, FIX2INT(iseq->location.first_lineno), RUBY_EVENT_CLASS);
		COMPILE(ret, "scoped node", node->nd_body);
		ADD_TRACE(ret, nd_line(node), RUBY_EVENT_END);
		break;
	    }
	  case ISEQ_TYPE_METHOD:
	    {
		ADD_TRACE(ret, FIX2INT(iseq->location.first_lineno), RUBY_EVENT_CALL);
		COMPILE(ret, "scoped node", node->nd_body);
		ADD_TRACE(ret, nd_line(node), RUBY_EVENT_RETURN);
		break;
	    }
	  default: {
	    COMPILE(ret, "scoped node", node->nd_body);
	    break;
	  }
	}
    }
    else {
	switch (iseq->type) {
	  case ISEQ_TYPE_METHOD:
	  case ISEQ_TYPE_CLASS:
	  case ISEQ_TYPE_BLOCK:
	  case ISEQ_TYPE_EVAL:
	  case ISEQ_TYPE_MAIN:
	  case ISEQ_TYPE_TOP:
	    rb_compile_error(ERROR_ARGS "compile/should not be reached: %s:%d",
			     __FILE__, __LINE__);
	    break;
	  case ISEQ_TYPE_RESCUE:
	    iseq_set_exception_local_table(iseq);
	    COMPILE(ret, "rescue", node);
	    break;
	  case ISEQ_TYPE_ENSURE:
	    iseq_set_exception_local_table(iseq);
	    COMPILE_POPED(ret, "ensure", node);
	    break;
	  case ISEQ_TYPE_DEFINED_GUARD:
	    iseq_set_local_table(iseq, 0);
	    COMPILE(ret, "defined guard", node);
	    break;
	  default:
	    rb_bug("unknown scope");
	}
    }

    if (iseq->type == ISEQ_TYPE_RESCUE || iseq->type == ISEQ_TYPE_ENSURE) {
	ADD_INSN2(ret, 0, getlocal, INT2FIX(2), INT2FIX(0));
	ADD_INSN1(ret, 0, throw, INT2FIX(0) /* continue throw */ );
    }
    else {
	ADD_INSN(ret, iseq->compile_data->last_line, leave);
    }

#if SUPPORT_JOKE
    if (iseq->compile_data->labels_table) {
	validate_labels(iseq, iseq->compile_data->labels_table);
    }
#endif
    return iseq_setup(iseq, ret);
}

int
rb_iseq_translate_threaded_code(rb_iseq_t *iseq)
{
#if OPT_DIRECT_THREADED_CODE || OPT_CALL_THREADED_CODE
    const void * const *table = rb_vm_get_insns_address_table();
    unsigned long i;

    iseq->iseq_encoded = ALLOC_N(VALUE, iseq->iseq_size);
    MEMCPY(iseq->iseq_encoded, iseq->iseq, VALUE, iseq->iseq_size);

    for (i = 0; i < iseq->iseq_size; /* */ ) {
	int insn = (int)iseq->iseq_encoded[i];
	int len = insn_len(insn);
	iseq->iseq_encoded[i] = (VALUE)table[insn];
	i += len;
    }
#else
    iseq->iseq_encoded = iseq->iseq;
#endif
    return COMPILE_OK;
}

/*********************************************/
/* definition of data structure for compiler */
/*********************************************/

static void *
compile_data_alloc(rb_iseq_t *iseq, size_t size)
{
    void *ptr = 0;
    struct iseq_compile_data_storage *storage =
	iseq->compile_data->storage_current;

    if (storage->pos + size > storage->size) {
	unsigned long alloc_size = storage->size * 2;

      retry:
	if (alloc_size < size) {
	    alloc_size *= 2;
	    goto retry;
	}
	storage->next = (void *)ALLOC_N(char, alloc_size +
					sizeof(struct
					       iseq_compile_data_storage));
	storage = iseq->compile_data->storage_current = storage->next;
	storage->next = 0;
	storage->pos = 0;
	storage->size = alloc_size;
	storage->buff = (char *)(&storage->buff + 1);
    }

    ptr = (void *)&storage->buff[storage->pos];
    storage->pos += size;
    return ptr;
}

static INSN *
compile_data_alloc_insn(rb_iseq_t *iseq)
{
    return (INSN *)compile_data_alloc(iseq, sizeof(INSN));
}

static LABEL *
compile_data_alloc_label(rb_iseq_t *iseq)
{
    return (LABEL *)compile_data_alloc(iseq, sizeof(LABEL));
}

static ADJUST *
compile_data_alloc_adjust(rb_iseq_t *iseq)
{
    return (ADJUST *)compile_data_alloc(iseq, sizeof(ADJUST));
}

/*
 * elem1, elemX => elem1, elem2, elemX
 */
static void
INSERT_ELEM_NEXT(LINK_ELEMENT *elem1, LINK_ELEMENT *elem2)
{
    elem2->next = elem1->next;
    elem2->prev = elem1;
    elem1->next = elem2;
    if (elem2->next) {
	elem2->next->prev = elem2;
    }
}

#if 0 /* unused */
/*
 * elemX, elem1 => elemX, elem2, elem1
 */
static void
INSERT_ELEM_PREV(LINK_ELEMENT *elem1, LINK_ELEMENT *elem2)
{
    elem2->prev = elem1->prev;
    elem2->next = elem1;
    elem1->prev = elem2;
    if (elem2->prev) {
	elem2->prev->next = elem2;
    }
}
#endif

/*
 * elemX, elem1, elemY => elemX, elem2, elemY
 */
static void
REPLACE_ELEM(LINK_ELEMENT *elem1, LINK_ELEMENT *elem2)
{
    elem2->prev = elem1->prev;
    elem2->next = elem1->next;
    if (elem1->prev) {
	elem1->prev->next = elem2;
    }
    if (elem1->next) {
	elem1->next->prev = elem2;
    }
}

static void
REMOVE_ELEM(LINK_ELEMENT *elem)
{
    elem->prev->next = elem->next;
    if (elem->next) {
	elem->next->prev = elem->prev;
    }
}

static LINK_ELEMENT *
FIRST_ELEMENT(LINK_ANCHOR *anchor)
{
    return anchor->anchor.next;
}

#if 0 /* unused */
static LINK_ELEMENT *
LAST_ELEMENT(LINK_ANCHOR *anchor)
{
  return anchor->last;
}
#endif

static LINK_ELEMENT *
POP_ELEMENT(ISEQ_ARG_DECLARE LINK_ANCHOR *anchor)
{
    LINK_ELEMENT *elem = anchor->last;
    anchor->last = anchor->last->prev;
    anchor->last->next = 0;
    verify_list("pop", anchor);
    return elem;
}
#if CPDEBUG < 0
#define POP_ELEMENT(anchor) POP_ELEMENT(iseq, (anchor))
#endif

#if 0 /* unused */
static LINK_ELEMENT *
SHIFT_ELEMENT(LINK_ANCHOR *anchor)
{
    LINK_ELEMENT *elem = anchor->anchor.next;
    if (elem) {
	anchor->anchor.next = elem->next;
    }
    return elem;
}
#endif

#if 0 /* unused */
static int
LIST_SIZE(LINK_ANCHOR *anchor)
{
    LINK_ELEMENT *elem = anchor->anchor.next;
    int size = 0;
    while (elem) {
	size += 1;
	elem = elem->next;
    }
    return size;
}
#endif

static int
LIST_SIZE_ZERO(LINK_ANCHOR *anchor)
{
    if (anchor->anchor.next == 0) {
	return 1;
    }
    else {
	return 0;
    }
}

/*
 * anc1: e1, e2, e3
 * anc2: e4, e5
 *#=>
 * anc1: e1, e2, e3, e4, e5
 * anc2: e4, e5 (broken)
 */
static void
APPEND_LIST(ISEQ_ARG_DECLARE LINK_ANCHOR *anc1, LINK_ANCHOR *anc2)
{
    if (anc2->anchor.next) {
	anc1->last->next = anc2->anchor.next;
	anc2->anchor.next->prev = anc1->last;
	anc1->last = anc2->last;
    }
    verify_list("append", anc1);
}
#if CPDEBUG < 0
#define APPEND_LIST(anc1, anc2) APPEND_LIST(iseq, (anc1), (anc2))
#endif

/*
 * anc1: e1, e2, e3
 * anc2: e4, e5
 *#=>
 * anc1: e4, e5, e1, e2, e3
 * anc2: e4, e5 (broken)
 */
static void
INSERT_LIST(ISEQ_ARG_DECLARE LINK_ANCHOR *anc1, LINK_ANCHOR *anc2)
{
    if (anc2->anchor.next) {
	LINK_ELEMENT *first = anc1->anchor.next;
	anc1->anchor.next = anc2->anchor.next;
	anc1->anchor.next->prev = &anc1->anchor;
	anc2->last->next = first;
	if (first) {
	    first->prev = anc2->last;
	}
	else {
	    anc1->last = anc2->last;
	}
    }

    verify_list("append", anc1);
}
#if CPDEBUG < 0
#define INSERT_LIST(anc1, anc2) INSERT_LIST(iseq, (anc1), (anc2))
#endif

#if 0 /* unused */
/*
 * anc1: e1, e2, e3
 * anc2: e4, e5
 *#=>
 * anc1: e4, e5
 * anc2: e1, e2, e3
 */
static void
SWAP_LIST(ISEQ_ARG_DECLARE LINK_ANCHOR *anc1, LINK_ANCHOR *anc2)
{
    LINK_ANCHOR tmp = *anc2;

    /* it has bug */
    *anc2 = *anc1;
    *anc1 = tmp;

    verify_list("swap1", anc1);
    verify_list("swap2", anc2);
}
#if CPDEBUG < 0
#define SWAP_LIST(anc1, anc2) SWAP_LIST(iseq, (anc1), (anc2))
#endif

static LINK_ANCHOR *
REVERSE_LIST(ISEQ_ARG_DECLARE LINK_ANCHOR *anc)
{
    LINK_ELEMENT *first, *last, *elem, *e;
    first = &anc->anchor;
    elem = first->next;
    last = anc->last;

    if (elem != 0) {
	anc->anchor.next = last;
	anc->last = elem;
    }
    else {
	/* null list */
	return anc;
    }
    while (elem) {
	e = elem->next;
	elem->next = elem->prev;
	elem->prev = e;
	elem = e;
    }

    first->next = last;
    last->prev = first;
    anc->last->next = 0;

    verify_list("reverse", anc);
    return anc;
}
#if CPDEBUG < 0
#define REVERSE_LIST(anc) REVERSE_LIST(iseq, (anc))
#endif
#endif

#if CPDEBUG && 0
static void
debug_list(ISEQ_ARG_DECLARE LINK_ANCHOR *anchor)
{
    LINK_ELEMENT *list = FIRST_ELEMENT(anchor);
    printf("----\n");
    printf("anch: %p, frst: %p, last: %p\n", &anchor->anchor,
	   anchor->anchor.next, anchor->last);
    while (list) {
	printf("curr: %p, next: %p, prev: %p, type: %d\n", list, list->next,
	       list->prev, FIX2INT(list->type));
	list = list->next;
    }
    printf("----\n");

    dump_disasm_list(anchor->anchor.next);
    verify_list("debug list", anchor);
}
#if CPDEBUG < 0
#define debug_list(anc) debug_list(iseq, (anc))
#endif
#endif

static LABEL *
new_label_body(rb_iseq_t *iseq, long line)
{
    LABEL *labelobj = compile_data_alloc_label(iseq);

    labelobj->link.type = ISEQ_ELEMENT_LABEL;
    labelobj->link.next = 0;

    labelobj->label_no = iseq->compile_data->label_no++;
    labelobj->sc_state = 0;
    labelobj->sp = -1;
    return labelobj;
}

static ADJUST *
new_adjust_body(rb_iseq_t *iseq, LABEL *label, int line)
{
    ADJUST *adjust = compile_data_alloc_adjust(iseq);
    adjust->link.type = ISEQ_ELEMENT_ADJUST;
    adjust->link.next = 0;
    adjust->label = label;
    adjust->line_no = line;
    return adjust;
}

static INSN *
new_insn_core(rb_iseq_t *iseq, int line_no,
	      int insn_id, int argc, VALUE *argv)
{
    INSN *iobj = compile_data_alloc_insn(iseq);
    /* printf("insn_id: %d, line: %d\n", insn_id, line_no); */

    iobj->link.type = ISEQ_ELEMENT_INSN;
    iobj->link.next = 0;
    iobj->insn_id = insn_id;
    iobj->line_no = line_no;
    iobj->operands = argv;
    iobj->operand_size = argc;
    iobj->sc_state = 0;
    return iobj;
}

static INSN *
new_insn_body(rb_iseq_t *iseq, int line_no, int insn_id, int argc, ...)
{
    VALUE *operands = 0;
    va_list argv;
    if (argc > 0) {
	int i;
	va_init_list(argv, argc);
	operands = (VALUE *)compile_data_alloc(iseq, sizeof(VALUE) * argc);
	for (i = 0; i < argc; i++) {
	    VALUE v = va_arg(argv, VALUE);
	    operands[i] = v;
	}
	va_end(argv);
    }
    return new_insn_core(iseq, line_no, insn_id, argc, operands);
}

static rb_call_info_t *
new_callinfo(rb_iseq_t *iseq, ID mid, int argc, VALUE block, unsigned long flag)
{
    rb_call_info_t *ci = (rb_call_info_t *)compile_data_alloc(iseq, sizeof(rb_call_info_t));
    ci->mid = mid;
    ci->flag = flag;
    ci->orig_argc = argc;
    ci->argc = argc;

    if (block) {
	GetISeqPtr(block, ci->blockiseq);
    }
    else {
	ci->blockiseq = 0;
	if (!(ci->flag & (VM_CALL_ARGS_SPLAT | VM_CALL_ARGS_BLOCKARG))) {
	    ci->flag |= VM_CALL_ARGS_SKIP_SETUP;
	}
    }
    ci->vmstat = 0;
    ci->blockptr = 0;
    ci->recv = Qundef;
    ci->call = 0; /* TODO: should set default function? */

    ci->aux.index = iseq->callinfo_size++;

    return ci;
}

static INSN *
new_insn_send(rb_iseq_t *iseq, int line_no, VALUE id, VALUE argc, VALUE block, VALUE flag)
{
    VALUE *operands = (VALUE *)compile_data_alloc(iseq, sizeof(VALUE) * 1);
    operands[0] = (VALUE)new_callinfo(iseq, SYM2ID(id), FIX2INT(argc), block, FIX2INT(flag));
    return new_insn_core(iseq, line_no, BIN(send), 1, operands);
}

static VALUE
new_child_iseq(rb_iseq_t *iseq, NODE *node,
	       VALUE name, VALUE parent, enum iseq_type type, int line_no)
{
    VALUE ret;

    debugs("[new_child_iseq]> ---------------------------------------\n");
    ret = rb_iseq_new_with_opt(node, name,
			       iseq_path(iseq->self), iseq_absolute_path(iseq->self),
			       INT2FIX(line_no), parent, type, iseq->compile_data->option);
    debugs("[new_child_iseq]< ---------------------------------------\n");
    iseq_add_mark_object(iseq, ret);
    return ret;
}

static int
iseq_setup(rb_iseq_t *iseq, LINK_ANCHOR *anchor)
{
    /* debugs("[compile step 2] (iseq_array_to_linkedlist)\n"); */

    if (compile_debug > 5)
	dump_disasm_list(FIRST_ELEMENT(anchor));

    debugs("[compile step 3.1 (iseq_optimize)]\n");
    iseq_optimize(iseq, anchor);

    if (compile_debug > 5)
	dump_disasm_list(FIRST_ELEMENT(anchor));

    if (iseq->compile_data->option->instructions_unification) {
	debugs("[compile step 3.2 (iseq_insns_unification)]\n");
	iseq_insns_unification(iseq, anchor);
	if (compile_debug > 5)
	    dump_disasm_list(FIRST_ELEMENT(anchor));
    }

    if (iseq->compile_data->option->stack_caching) {
	debugs("[compile step 3.3 (iseq_set_sequence_stackcaching)]\n");
	iseq_set_sequence_stackcaching(iseq, anchor);
	if (compile_debug > 5)
	    dump_disasm_list(FIRST_ELEMENT(anchor));
    }

    debugs("[compile step 4.1 (iseq_set_sequence)]\n");
    iseq_set_sequence(iseq, anchor);
    if (compile_debug > 5)
	dump_disasm_list(FIRST_ELEMENT(anchor));

    debugs("[compile step 4.2 (iseq_set_exception_table)]\n");
    iseq_set_exception_table(iseq);

    debugs("[compile step 4.3 (set_optargs_table)] \n");
    iseq_set_optargs_table(iseq);

    debugs("[compile step 5 (iseq_translate_threaded_code)] \n");
    rb_iseq_translate_threaded_code(iseq);

    if (compile_debug > 1) {
	VALUE str = rb_iseq_disasm(iseq->self);
	printf("%s\n", StringValueCStr(str));
	fflush(stdout);
    }
    debugs("[compile step: finish]\n");

    return 0;
}

static int
iseq_set_exception_local_table(rb_iseq_t *iseq)
{
    ID id_dollar_bang;

    CONST_ID(id_dollar_bang, "#$!");
    iseq->local_table = (ID *)ALLOC_N(ID, 1);
    iseq->local_table_size = 1;
    iseq->local_size = iseq->local_table_size + 1;
    iseq->local_table[0] = id_dollar_bang;
    return COMPILE_OK;
}

static int
get_lvar_level(rb_iseq_t *iseq)
{
    int lev = 0;
    while (iseq != iseq->local_iseq) {
	lev++;
	iseq = iseq->parent_iseq;
    }
    return lev;
}

static int
get_dyna_var_idx_at_raw(rb_iseq_t *iseq, ID id)
{
    int i;

    for (i = 0; i < iseq->local_table_size; i++) {
	if (iseq->local_table[i] == id) {
	    return i;
	}
    }
    return -1;
}

static int
get_local_var_idx(rb_iseq_t *iseq, ID id)
{
    int idx = get_dyna_var_idx_at_raw(iseq->local_iseq, id);

    if (idx < 0) {
	rb_bug("get_local_var_idx: %d", idx);
    }

    return idx;
}

static int
get_dyna_var_idx(rb_iseq_t *iseq, ID id, int *level, int *ls)
{
    int lv = 0, idx = -1;

    while (iseq) {
	idx = get_dyna_var_idx_at_raw(iseq, id);
	if (idx >= 0) {
	    break;
	}
	iseq = iseq->parent_iseq;
	lv++;
    }

    if (idx < 0) {
	rb_bug("get_dyna_var_idx: -1");
    }

    *level = lv;
    *ls = iseq->local_size;
    return idx;
}

static int
iseq_set_arguments(rb_iseq_t *iseq, LINK_ANCHOR *optargs, NODE *node_args)
{
    debugs("iseq_set_arguments: %s\n", node_args ? "" : "0");

    if (node_args) {
	struct rb_args_info *args = node_args->nd_ainfo;
	ID rest_id = 0;
	int last_comma = 0;
	ID block_id = 0;

	if (nd_type(node_args) != NODE_ARGS) {
	    rb_bug("iseq_set_arguments: NODE_ARGS is expected, but %s",
		   ruby_node_name(nd_type(node_args)));
	}


	iseq->argc = (int)args->pre_args_num;
	debugs("  - argc: %d\n", iseq->argc);

	rest_id = args->rest_arg;
	if (rest_id == 1) {
	    last_comma = 1;
	    rest_id = 0;
	}
	block_id = args->block_arg;

	if (args->first_post_arg) {
	    iseq->arg_post_start = get_dyna_var_idx_at_raw(iseq, args->first_post_arg);
	    iseq->arg_post_len = args->post_args_num;
	}

	if (args->opt_args) {
	    NODE *node = args->opt_args;
	    LABEL *label;
	    VALUE labels = rb_ary_tmp_new(1);
	    int i = 0, j;

	    while (node) {
		label = NEW_LABEL(nd_line(node));
		rb_ary_push(labels, (VALUE)label | 1);
		ADD_LABEL(optargs, label);
		COMPILE_POPED(optargs, "optarg", node->nd_body);
		node = node->nd_next;
		i += 1;
	    }

	    /* last label */
	    label = NEW_LABEL(nd_line(node_args));
	    rb_ary_push(labels, (VALUE)label | 1);
	    ADD_LABEL(optargs, label);
	    i += 1;

	    iseq->arg_opts = i;
	    iseq->arg_opt_table = ALLOC_N(VALUE, i);
	    MEMCPY(iseq->arg_opt_table, RARRAY_PTR(labels), VALUE, i);
	    for (j = 0; j < i; j++) {
		iseq->arg_opt_table[j] &= ~1;
	    }
	    rb_ary_clear(labels);
	}
	else {
	    iseq->arg_opts = 0;
	}

	if (args->kw_args) {
	    NODE *node = args->kw_args;
	    VALUE keywords = rb_ary_tmp_new(1);
	    VALUE required = 0;
	    int i = 0, j, r = 0;

	    iseq->arg_keyword = get_dyna_var_idx_at_raw(iseq, args->kw_rest_arg->nd_vid);
	    COMPILE(optargs, "kwarg", args->kw_rest_arg);
	    while (node) {
		VALUE list = keywords;
		if (node->nd_body->nd_value == (NODE *)-1) {
		    ++r;
		    if (!required) required = rb_ary_tmp_new(1);
		    list = required;
		}
		rb_ary_push(list, INT2FIX(node->nd_body->nd_vid));
		COMPILE_POPED(optargs, "kwarg", node); /* nd_type(node) == NODE_KW_ARG */
		node = node->nd_next;
		i += 1;
	    }
	    iseq->arg_keyword_check = (args->kw_rest_arg->nd_vid & ID_SCOPE_MASK) == ID_JUNK;
	    iseq->arg_keywords = i;
	    iseq->arg_keyword_required = r;
	    iseq->arg_keyword_table = ALLOC_N(ID, i);
	    if (r) {
		rb_ary_concat(required, keywords);
		keywords = required;
	    }
	    for (j = 0; j < i; j++) {
		iseq->arg_keyword_table[j] = FIX2INT(RARRAY_AREF(keywords, j));
	    }
	    ADD_INSN(optargs, nd_line(args->kw_args), pop);
	}
	else if (args->kw_rest_arg) {
	    iseq->arg_keyword = get_dyna_var_idx_at_raw(iseq, args->kw_rest_arg->nd_vid);
	    COMPILE(optargs, "kwarg", args->kw_rest_arg);
	    ADD_INSN(optargs, nd_line(args->kw_rest_arg), pop);
	}
	else {
	    iseq->arg_keyword = -1;
	}

	if (args->pre_init) { /* m_init */
	    COMPILE_POPED(optargs, "init arguments (m)", args->pre_init);
	}
	if (args->post_init) { /* p_init */
	    COMPILE_POPED(optargs, "init arguments (p)", args->post_init);
	}

	if (rest_id) {
	    iseq->arg_rest = get_dyna_var_idx_at_raw(iseq, rest_id);

	    if (iseq->arg_rest == -1) {
		rb_bug("arg_rest: -1");
	    }

	    if (iseq->arg_post_start == 0) {
		iseq->arg_post_start = iseq->arg_rest + 1;
	    }
	}

	if (block_id) {
	    iseq->arg_block = get_dyna_var_idx_at_raw(iseq, block_id);
	}

	if (iseq->arg_opts != 0 || iseq->arg_post_len != 0 ||
	    iseq->arg_rest != -1 || iseq->arg_block != -1 ||
	    iseq->arg_keyword != -1) {
	    iseq->arg_simple = 0;

	    /* set arg_size: size of arguments */
	    if (iseq->arg_keyword != -1) {
		iseq->arg_size = iseq->arg_keyword + 1;
	    }
	    else if (iseq->arg_block != -1) {
		iseq->arg_size = iseq->arg_block + 1;
	    }
	    else if (iseq->arg_post_len) {
		iseq->arg_size = iseq->arg_post_start + iseq->arg_post_len;
	    }
	    else if (iseq->arg_rest != -1) {
		iseq->arg_size = iseq->arg_rest + 1;
	    }
	    else if (iseq->arg_opts) {
		iseq->arg_size = iseq->argc + iseq->arg_opts - 1;
	    }
	    else {
		iseq->arg_size = iseq->argc;
	    }
	}
	else {
	    iseq->arg_simple = 1;
	    iseq->arg_size = iseq->argc;
	}

	if (iseq->type == ISEQ_TYPE_BLOCK) {
	    if (iseq->arg_opts == 0 && iseq->arg_post_len == 0 &&
		iseq->arg_rest == -1 && iseq->arg_keyword == -1) {
		if (iseq->argc == 1 && last_comma == 0) {
		    /* {|a|} */
		    iseq->arg_simple |= 0x02;
		}
	    }
	}
    }
    else {
	iseq->arg_simple = 1;
    }

    return COMPILE_OK;
}

static int
iseq_set_local_table(rb_iseq_t *iseq, ID *tbl)
{
    int size;

    if (tbl) {
	size = (int)*tbl;
	tbl++;
    }
    else {
	size = 0;
    }

    if (size > 0) {
	iseq->local_table = (ID *)ALLOC_N(ID, size);
	MEMCPY(iseq->local_table, tbl, ID, size);
    }

    iseq->local_size = iseq->local_table_size = size;
    iseq->local_size += 1;
    /*
      if (lfp == dfp ) { // top, class, method
	  dfp[-1]: svar
      else {             // block
          dfp[-1]: cref
      }
     */

    debugs("iseq_set_local_table: %d, %d\n", iseq->local_size, iseq->local_table_size);
    return COMPILE_OK;
}

static int
cdhash_cmp(VALUE val, VALUE lit)
{
    if (val == lit) return 0;
    if (SPECIAL_CONST_P(lit)) {
	return val != lit;
    }
    if (SPECIAL_CONST_P(val) || BUILTIN_TYPE(val) != BUILTIN_TYPE(lit)) {
	return -1;
    }
    if (BUILTIN_TYPE(lit) == T_STRING) {
	return rb_str_hash_cmp(lit, val);
    }
    return !rb_eql(lit, val);
}

static st_index_t
cdhash_hash(VALUE a)
{
    if (SPECIAL_CONST_P(a)) return (st_index_t)a;
    if (RB_TYPE_P(a, T_STRING)) return rb_str_hash(a);
    {
	VALUE hval = rb_hash(a);
	return (st_index_t)FIX2LONG(hval);
    }
}

static const struct st_hash_type cdhash_type = {
    cdhash_cmp,
    cdhash_hash,
};

struct cdhash_set_label_struct {
    VALUE hash;
    int pos;
    int len;
};

static int
cdhash_set_label_i(VALUE key, VALUE val, void *ptr)
{
    struct cdhash_set_label_struct *data = (struct cdhash_set_label_struct *)ptr;
    LABEL *lobj = (LABEL *)(val & ~1);
    rb_hash_aset(data->hash, key, INT2FIX(lobj->position - (data->pos+data->len)));
    return ST_CONTINUE;
}

/**
  ruby insn object list -> raw instruction sequence
 */
static int
iseq_set_sequence(rb_iseq_t *iseq, LINK_ANCHOR *anchor)
{
    LABEL *lobj;
    INSN *iobj;
    struct iseq_line_info_entry *line_info_table;
    unsigned int last_line = 0;
    LINK_ELEMENT *list;
    VALUE *generated_iseq;

    int k, pos, sp, stack_max = 0, line = 0;

    /* set label position */
    list = FIRST_ELEMENT(anchor);
    k = pos = 0;
    while (list) {
	switch (list->type) {
	  case ISEQ_ELEMENT_INSN:
	    {
		iobj = (INSN *)list;
		line = iobj->line_no;
		pos += insn_data_length(iobj);
		k++;
		break;
	    }
	  case ISEQ_ELEMENT_LABEL:
	    {
		lobj = (LABEL *)list;
		lobj->position = pos;
		lobj->set = TRUE;
		break;
	    }
	  case ISEQ_ELEMENT_NONE:
	    {
		/* ignore */
		break;
	    }
	  case ISEQ_ELEMENT_ADJUST:
	    {
		ADJUST *adjust = (ADJUST *)list;
		if (adjust->line_no != -1) {
		    pos += 2 /* insn + 1 operand */;
		    k++;
		}
		break;
	    }
	  default:
	    dump_disasm_list(FIRST_ELEMENT(anchor));
	    dump_disasm_list(list);
	    rb_compile_error(RSTRING_PTR(iseq->location.path), line,
			     "error: set_sequence");
	    break;
	}
	list = list->next;
    }

    /* make instruction sequence */
    generated_iseq = ALLOC_N(VALUE, pos);
    line_info_table = ALLOC_N(struct iseq_line_info_entry, k);
    iseq->ic_entries = ALLOC_N(struct iseq_inline_cache_entry, iseq->ic_size);
    MEMZERO(iseq->ic_entries, struct iseq_inline_cache_entry, iseq->ic_size);
    iseq->callinfo_entries = ALLOC_N(rb_call_info_t, iseq->callinfo_size);
    /* MEMZERO(iseq->callinfo_entries, rb_call_info_t, iseq->callinfo_size); */

    list = FIRST_ELEMENT(anchor);
    k = pos = sp = 0;

    while (list) {
	switch (list->type) {
	  case ISEQ_ELEMENT_INSN:
	    {
		int j, len, insn;
		const char *types;
		VALUE *operands;

		iobj = (INSN *)list;

		/* update sp */
		sp = calc_sp_depth(sp, iobj);
		if (sp > stack_max) {
		    stack_max = sp;
		}

		/* fprintf(stderr, "insn: %-16s, sp: %d\n", insn_name(iobj->insn_id), sp); */
		operands = iobj->operands;
		insn = iobj->insn_id;
		generated_iseq[pos] = insn;
		types = insn_op_types(insn);
		len = insn_len(insn);

		/* operand check */
		if (iobj->operand_size != len - 1) {
		    /* printf("operand size miss! (%d, %d)\n", iobj->operand_size, len); */
		    dump_disasm_list(list);
		    rb_compile_error(RSTRING_PTR(iseq->location.path), iobj->line_no,
				     "operand size miss! (%d for %d)",
				     iobj->operand_size, len - 1);
		    xfree(generated_iseq);
		    xfree(line_info_table);
		    return 0;
		}

		for (j = 0; types[j]; j++) {
		    char type = types[j];
		    /* printf("--> [%c - (%d-%d)]\n", type, k, j); */
		    switch (type) {
		      case TS_OFFSET:
			{
			    /* label(destination position) */
			    lobj = (LABEL *)operands[j];
			    if (!lobj->set) {
				rb_compile_error(RSTRING_PTR(iseq->location.path), iobj->line_no,
						 "unknown label");
			    }
			    if (lobj->sp == -1) {
				lobj->sp = sp;
			    }
			    generated_iseq[pos + 1 + j] = lobj->position - (pos + len);
			    break;
			}
		      case TS_CDHASH:
			{
			    VALUE map = operands[j];
			    struct cdhash_set_label_struct data;
                            data.hash = map;
                            data.pos = pos;
                            data.len = len;
			    rb_hash_foreach(map, cdhash_set_label_i, (VALUE)&data);

			    hide_obj(map);
			    generated_iseq[pos + 1 + j] = map;
			    break;
			}
		      case TS_LINDEX:
		      case TS_NUM:	/* ulong */
			generated_iseq[pos + 1 + j] = FIX2INT(operands[j]);
			break;
		      case TS_ISEQ:	/* iseq */
			{
			    VALUE v = operands[j];
			    rb_iseq_t *block = 0;
			    if (v) {
				GetISeqPtr(v, block);
			    }
			    generated_iseq[pos + 1 + j] = (VALUE)block;
			    break;
			}
		      case TS_VALUE:	/* VALUE */
			{
			    VALUE v = operands[j];
			    generated_iseq[pos + 1 + j] = v;
			    /* to mark ruby object */
			    iseq_add_mark_object(iseq, v);
			    break;
			}
		      case TS_IC: /* inline cache */
			{
			    int ic_index = FIX2INT(operands[j]);
			    IC ic = &iseq->ic_entries[ic_index];
			    if (UNLIKELY(ic_index >= iseq->ic_size)) {
				rb_bug("iseq_set_sequence: ic_index overflow: index: %d, size: %d", ic_index, iseq->ic_size);
			    }
			    generated_iseq[pos + 1 + j] = (VALUE)ic;
			    break;
			}
		      case TS_CALLINFO: /* call info */
			{
			    rb_call_info_t *base_ci = (rb_call_info_t *)operands[j];
			    rb_call_info_t *ci = &iseq->callinfo_entries[base_ci->aux.index];
			    *ci = *base_ci;

			    if (UNLIKELY(base_ci->aux.index >= iseq->callinfo_size)) {
				rb_bug("iseq_set_sequence: ci_index overflow: index: %d, size: %d", base_ci->argc, iseq->callinfo_size);
			    }
			    generated_iseq[pos + 1 + j] = (VALUE)ci;
			    break;
			}
		      case TS_ID: /* ID */
			generated_iseq[pos + 1 + j] = SYM2ID(operands[j]);
			break;
		      case TS_GENTRY:
			{
			    struct rb_global_entry *entry =
				(struct rb_global_entry *)(operands[j] & (~1));
			    generated_iseq[pos + 1 + j] = (VALUE)entry;
			}
			break;
		      default:
			rb_compile_error(RSTRING_PTR(iseq->location.path), iobj->line_no,
					 "unknown operand type: %c", type);
			xfree(generated_iseq);
			xfree(line_info_table);
			return 0;
		    }
		}
		if (last_line != iobj->line_no) {
		    line_info_table[k].line_no = last_line = iobj->line_no;
		    line_info_table[k].position = pos;
		    k++;
		}
		pos += len;
		break;
	    }
	  case ISEQ_ELEMENT_LABEL:
	    {
		lobj = (LABEL *)list;
		if (lobj->sp == -1) {
		    lobj->sp = sp;
		}
		else {
		    sp = lobj->sp;
		}
		break;
	    }
	  case ISEQ_ELEMENT_ADJUST:
	    {
		ADJUST *adjust = (ADJUST *)list;
		int orig_sp = sp;

		if (adjust->label) {
		    sp = adjust->label->sp;
		}
		else {
		    sp = 0;
		}

		if (adjust->line_no != -1) {
		    if (orig_sp - sp > 0) {
			if (last_line != (unsigned int)adjust->line_no) {
			    line_info_table[k].line_no = last_line = adjust->line_no;
			    line_info_table[k].position = pos;
			    k++;
			}
			generated_iseq[pos++] = BIN(adjuststack);
			generated_iseq[pos++] = orig_sp - sp;
		    }
		    else if (orig_sp - sp == 0) {
			/* jump to next insn */
			if (last_line != (unsigned int)adjust->line_no) {
			    line_info_table[k].line_no = last_line = adjust->line_no;
			    line_info_table[k].position = pos;
			    k++;
			}
			generated_iseq[pos++] = BIN(jump);
			generated_iseq[pos++] = 0;
		    }
		    else {
			rb_bug("iseq_set_sequence: adjust bug");
		    }
		}
		break;
	    }
	  default:
	    /* ignore */
	    break;
	}
	list = list->next;
    }

#if 0 /* XXX */
    /* this check need dead code elimination */
    if (sp != 1) {
	rb_bug("SP is not 0 on %s (%d)\n", RSTRING_PTR(iseq->name), sp);
    }
#endif

    iseq->iseq = (void *)generated_iseq;
    iseq->iseq_size = pos;
    iseq->stack_max = stack_max;

    line_info_table = ruby_xrealloc(line_info_table, k * sizeof(struct iseq_line_info_entry));
    iseq->line_info_table = line_info_table;
    iseq->line_info_size = k;

    return COMPILE_OK;
}

static int
label_get_position(LABEL *lobj)
{
    return lobj->position;
}

static int
label_get_sp(LABEL *lobj)
{
    return lobj->sp;
}

static int
iseq_set_exception_table(rb_iseq_t *iseq)
{
    VALUE *tptr, *ptr;
    int tlen, i;
    struct iseq_catch_table_entry *entry;

    tlen = (int)RARRAY_LEN(iseq->compile_data->catch_table_ary);
    tptr = RARRAY_PTR(iseq->compile_data->catch_table_ary);

    iseq->catch_table = tlen ? ALLOC_N(struct iseq_catch_table_entry, tlen) : 0;
    iseq->catch_table_size = tlen;

    for (i = 0; i < tlen; i++) {
	ptr = RARRAY_PTR(tptr[i]);
	entry = &iseq->catch_table[i];
	entry->type = (enum catch_type)(ptr[0] & 0xffff);
	entry->start = label_get_position((LABEL *)(ptr[1] & ~1));
	entry->end = label_get_position((LABEL *)(ptr[2] & ~1));
	entry->iseq = ptr[3];

	/* register iseq as mark object */
	if (entry->iseq != 0) {
	    iseq_add_mark_object(iseq, entry->iseq);
	}

	/* stack depth */
	if (ptr[4]) {
	    LABEL *lobj = (LABEL *)(ptr[4] & ~1);
	    entry->cont = label_get_position(lobj);
	    entry->sp = label_get_sp(lobj);

	    /* TODO: Dirty Hack!  Fix me */
	    if (entry->type == CATCH_TYPE_RESCUE ||
		entry->type == CATCH_TYPE_BREAK ||
		entry->type == CATCH_TYPE_NEXT) {
		entry->sp--;
	    }
	}
	else {
	    entry->cont = 0;
	}
    }

    OBJ_WRITE(iseq->self, &iseq->compile_data->catch_table_ary, 0); /* free */
    return COMPILE_OK;
}

/*
 * set optional argument table
 *   def foo(a, b=expr1, c=expr2)
 *   =>
 *    b:
 *      expr1
 *    c:
 *      expr2
 */
static int
iseq_set_optargs_table(rb_iseq_t *iseq)
{
    int i;

    if (iseq->arg_opts != 0) {
	for (i = 0; i < iseq->arg_opts; i++) {
	    iseq->arg_opt_table[i] =
		label_get_position((LABEL *)iseq->arg_opt_table[i]);
	}
    }
    return COMPILE_OK;
}

static LINK_ELEMENT *
get_destination_insn(INSN *iobj)
{
    LABEL *lobj = (LABEL *)OPERAND_AT(iobj, 0);
    LINK_ELEMENT *list;

    list = lobj->link.next;
    while (list) {
	if (list->type == ISEQ_ELEMENT_INSN || list->type == ISEQ_ELEMENT_ADJUST) {
	    break;
	}
	list = list->next;
    }
    return list;
}

static LINK_ELEMENT *
get_next_insn(INSN *iobj)
{
    LINK_ELEMENT *list = iobj->link.next;

    while (list) {
	if (list->type == ISEQ_ELEMENT_INSN || list->type == ISEQ_ELEMENT_ADJUST) {
	    return list;
	}
	list = list->next;
    }
    return 0;
}

static LINK_ELEMENT *
get_prev_insn(INSN *iobj)
{
    LINK_ELEMENT *list = iobj->link.prev;

    while (list) {
	if (list->type == ISEQ_ELEMENT_INSN || list->type == ISEQ_ELEMENT_ADJUST) {
	    return list;
	}
	list = list->prev;
    }
    return 0;
}

static int
iseq_peephole_optimize(rb_iseq_t *iseq, LINK_ELEMENT *list, const int do_tailcallopt)
{
    INSN *iobj = (INSN *)list;
  again:
    if (iobj->insn_id == BIN(jump)) {
	INSN *niobj, *diobj, *piobj;
	/*
	 *  useless jump elimination:
	 *     jump LABEL1
	 *     ...
	 *   LABEL1:
	 *     jump LABEL2
	 *
	 *   => in this case, first jump instruction should jump to
	 *      LABEL2 directly
	 */
	diobj = (INSN *)get_destination_insn(iobj);
	niobj = (INSN *)get_next_insn(iobj);

	if (diobj == niobj) {
	    /*
	     *   jump LABEL
	     *  LABEL:
	     * =>
	     *   LABEL:
	     */
	    REMOVE_ELEM(&iobj->link);
	}
	else if (iobj != diobj && diobj->insn_id == BIN(jump)) {
	    if (OPERAND_AT(iobj, 0) != OPERAND_AT(diobj, 0)) {
		OPERAND_AT(iobj, 0) = OPERAND_AT(diobj, 0);
		goto again;
	    }
	}
	else if (diobj->insn_id == BIN(leave)) {
	    /*
	     *  jump LABEL
	     *  ...
	     * LABEL:
	     *  leave
	     * =>
	     *  leave
	     *  ...
	     * LABEL:
	     *  leave
	     */
	    INSN *eiobj = new_insn_core(iseq, iobj->line_no, BIN(leave),
					diobj->operand_size, diobj->operands);
	    INSN *popiobj = new_insn_core(iseq, iobj->line_no,
					  BIN(pop), 0, 0);
	    /* replace */
	    REPLACE_ELEM((LINK_ELEMENT *)iobj, (LINK_ELEMENT *)eiobj);
	    INSERT_ELEM_NEXT((LINK_ELEMENT *)eiobj, (LINK_ELEMENT *)popiobj);
	    iobj = popiobj;
	}
	/*
	 * useless jump elimination (if/unless destination):
	 *   if   L1
	 *   jump L2
	 * L1:
	 *   ...
	 * L2:
	 *
	 * ==>
	 *   unless L2
	 * L1:
	 *   ...
	 * L2:
	 */
	else if ((piobj = (INSN *)get_prev_insn(iobj)) != 0 &&
		 (piobj->insn_id == BIN(branchif) ||
		  piobj->insn_id == BIN(branchunless))) {
	    if (niobj == (INSN *)get_destination_insn(piobj)) {
		piobj->insn_id = (piobj->insn_id == BIN(branchif))
		  ? BIN(branchunless) : BIN(branchif);
		OPERAND_AT(piobj, 0) = OPERAND_AT(iobj, 0);
		REMOVE_ELEM(&iobj->link);
	    }
	}
    }

    if (iobj->insn_id == BIN(branchif) ||
	iobj->insn_id == BIN(branchunless)) {
	/*
	 *   if L1
	 *   ...
	 * L1:
	 *   jump L2
	 * =>
	 *   if L2
	 */
	INSN *nobj = (INSN *)get_destination_insn(iobj);
	if (nobj->insn_id == BIN(jump)) {
	    OPERAND_AT(iobj, 0) = OPERAND_AT(nobj, 0);
	}
    }

    if (do_tailcallopt && iobj->insn_id == BIN(leave)) {
	/*
	 *  send ...
	 *  leave
	 * =>
	 *  send ..., ... | VM_CALL_TAILCALL, ...
	 *  leave # unreachable
	 */
	INSN *piobj = (INSN *)get_prev_insn((INSN *)list);

	if (piobj->insn_id == BIN(send) || piobj->insn_id == BIN(opt_send_simple)) {
	    rb_call_info_t *ci = (rb_call_info_t *)piobj->operands[0];
	    if (ci->blockiseq == 0) {
		ci->flag |= VM_CALL_TAILCALL;
	    }
	}
    }
    return COMPILE_OK;
}

static int
insn_set_specialized_instruction(rb_iseq_t *iseq, INSN *iobj, int insn_id)
{
    int old_opsize = iobj->operand_size;
    iobj->insn_id = insn_id;
    iobj->operand_size = insn_len(insn_id) - 1;

    if (iobj->operand_size > old_opsize) {
	VALUE *old_operands = iobj->operands;
	if (insn_id != BIN(opt_neq)) {
	    rb_bug("insn_set_specialized_instruction: unknown insn: %d", insn_id);
	}
	iobj->operands = (VALUE *)compile_data_alloc(iseq, iobj->operand_size * sizeof(VALUE));
	iobj->operands[0] = old_operands[0];
	iobj->operands[1] = (VALUE)new_callinfo(iseq, idEq, 1, 0, 0);
    }

    return COMPILE_OK;
}

static int
iseq_specialized_instruction(rb_iseq_t *iseq, INSN *iobj)
{
    if (iobj->insn_id == BIN(send)) {
	rb_call_info_t *ci = (rb_call_info_t *)OPERAND_AT(iobj, 0);

#define SP_INSN(opt) insn_set_specialized_instruction(iseq, iobj, BIN(opt_##opt))
	if (ci->blockiseq == 0 && (ci->flag & ~VM_CALL_ARGS_SKIP_SETUP) == 0) {
	    switch (ci->orig_argc) {
	      case 0:
		switch (ci->mid) {
		  case idLength: SP_INSN(length); return COMPILE_OK;
		  case idSize:	 SP_INSN(size);	  return COMPILE_OK;
		  case idEmptyP: SP_INSN(empty_p);return COMPILE_OK;
		  case idSucc:	 SP_INSN(succ);	  return COMPILE_OK;
		  case idNot:	 SP_INSN(not);	  return COMPILE_OK;
		}
		break;
	      case 1:
		switch (ci->mid) {
		  case idPLUS:	 SP_INSN(plus);	  return COMPILE_OK;
		  case idMINUS:	 SP_INSN(minus);  return COMPILE_OK;
		  case idMULT:	 SP_INSN(mult);	  return COMPILE_OK;
		  case idDIV:	 SP_INSN(div);	  return COMPILE_OK;
		  case idMOD:	 SP_INSN(mod);	  return COMPILE_OK;
		  case idEq:	 SP_INSN(eq);	  return COMPILE_OK;
		  case idNeq:	 SP_INSN(neq);	  return COMPILE_OK;
		  case idLT:	 SP_INSN(lt);	  return COMPILE_OK;
		  case idLE:	 SP_INSN(le);	  return COMPILE_OK;
		  case idGT:	 SP_INSN(gt);	  return COMPILE_OK;
		  case idGE:	 SP_INSN(ge);	  return COMPILE_OK;
		  case idLTLT:	 SP_INSN(ltlt);	  return COMPILE_OK;
		  case idAREF:	 SP_INSN(aref);	  return COMPILE_OK;
		}
		break;
	    }
	}
	if (ci->flag & VM_CALL_ARGS_SKIP_SETUP) {
	    iobj->insn_id = BIN(opt_send_simple);
	}
    }
#undef SP_INSN

    return COMPILE_OK;
}

static int
iseq_optimize(rb_iseq_t *iseq, LINK_ANCHOR *anchor)
{
    LINK_ELEMENT *list;
    const int do_peepholeopt = iseq->compile_data->option->peephole_optimization;
    const int do_tailcallopt = iseq->compile_data->option->tailcall_optimization;
    const int do_si = iseq->compile_data->option->specialized_instruction;
    const int do_ou = iseq->compile_data->option->operands_unification;
    list = FIRST_ELEMENT(anchor);

    while (list) {
	if (list->type == ISEQ_ELEMENT_INSN) {
	    if (do_peepholeopt) {
		iseq_peephole_optimize(iseq, list, do_tailcallopt);
	    }
	    if (do_si) {
		iseq_specialized_instruction(iseq, (INSN *)list);
	    }
	    if (do_ou) {
		insn_operands_unification((INSN *)list);
	    }
	}
	list = list->next;
    }
    return COMPILE_OK;
}

#if OPT_INSTRUCTIONS_UNIFICATION
static INSN *
new_unified_insn(rb_iseq_t *iseq,
		 int insn_id, int size, LINK_ELEMENT *seq_list)
{
    INSN *iobj = 0;
    LINK_ELEMENT *list = seq_list;
    int i, argc = 0;
    VALUE *operands = 0, *ptr = 0;


    /* count argc */
    for (i = 0; i < size; i++) {
	iobj = (INSN *)list;
	argc += iobj->operand_size;
	list = list->next;
    }

    if (argc > 0) {
	ptr = operands =
	    (VALUE *)compile_data_alloc(iseq, sizeof(VALUE) * argc);
    }

    /* copy operands */
    list = seq_list;
    for (i = 0; i < size; i++) {
	i…