Fresh start

1 files changed, 3079 insertions, 0 deletions

diff --git a/jni/ruby/vm.c b/jni/ruby/vm.c
new file mode 100644
index 0000000..27aa8e0
--- /dev/null
+++ b/jni/ruby/vm.c
@@ -0,0 +1,3079 @@
+/**********************************************************************
+
+  vm.c -
+
+  $Author: nagachika $
+
+  Copyright (C) 2004-2007 Koichi Sasada
+
+**********************************************************************/
+
+#include "internal.h"
+#include "ruby/vm.h"
+#include "ruby/st.h"
+
+#include "gc.h"
+#include "vm_core.h"
+#include "iseq.h"
+#include "eval_intern.h"
+#include "probes.h"
+#include "probes_helper.h"
+
+static inline VALUE *
+VM_EP_LEP(VALUE *ep)
+{
+    while (!VM_EP_LEP_P(ep)) {
+	ep = VM_EP_PREV_EP(ep);
+    }
+    return ep;
+}
+
+static inline rb_control_frame_t *
+rb_vm_search_cf_from_ep(const rb_thread_t * const th, rb_control_frame_t *cfp, const VALUE * const ep)
+{
+    if (!ep) {
+	return NULL;
+    }
+    else {
+	const rb_control_frame_t * const eocfp = RUBY_VM_END_CONTROL_FRAME(th); /* end of control frame pointer */
+
+	while (cfp < eocfp) {
+	    if (cfp->ep == ep) {
+		return cfp;
+	    }
+	    cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);
+	}
+
+	return NULL;
+    }
+}
+
+VALUE *
+rb_vm_ep_local_ep(VALUE *ep)
+{
+    return VM_EP_LEP(ep);
+}
+
+static inline VALUE *
+VM_CF_LEP(rb_control_frame_t *cfp)
+{
+    return VM_EP_LEP(cfp->ep);
+}
+
+static inline VALUE *
+VM_CF_PREV_EP(rb_control_frame_t * cfp)
+{
+    return VM_EP_PREV_EP((cfp)->ep);
+}
+
+static inline rb_block_t *
+VM_CF_BLOCK_PTR(rb_control_frame_t *cfp)
+{
+    VALUE *ep = VM_CF_LEP(cfp);
+    return VM_EP_BLOCK_PTR(ep);
+}
+
+rb_block_t *
+rb_vm_control_frame_block_ptr(rb_control_frame_t *cfp)
+{
+    return VM_CF_BLOCK_PTR(cfp);
+}
+
+#if VM_COLLECT_USAGE_DETAILS
+static void vm_collect_usage_operand(int insn, int n, VALUE op);
+static void vm_collect_usage_insn(int insn);
+static void vm_collect_usage_register(int reg, int isset);
+#endif
+
+static VALUE
+vm_invoke_proc(rb_thread_t *th, rb_proc_t *proc, VALUE self, VALUE defined_class,
+	       int argc, const VALUE *argv, const rb_block_t *blockptr);
+
+static rb_serial_t ruby_vm_global_method_state = 1;
+static rb_serial_t ruby_vm_global_constant_state = 1;
+static rb_serial_t ruby_vm_class_serial = 1;
+
+#include "vm_insnhelper.h"
+#include "vm_insnhelper.c"
+#include "vm_exec.h"
+#include "vm_exec.c"
+
+#include "vm_method.c"
+#include "vm_eval.c"
+
+#include <assert.h>
+
+#define PROCDEBUG 0
+
+rb_serial_t
+rb_next_class_serial(void)
+{
+    return NEXT_CLASS_SERIAL();
+}
+
+VALUE rb_cRubyVM;
+VALUE rb_cThread;
+VALUE rb_cEnv;
+VALUE rb_mRubyVMFrozenCore;
+
+#define ruby_vm_redefined_flag GET_VM()->redefined_flag
+VALUE ruby_vm_const_missing_count = 0;
+rb_thread_t *ruby_current_thread = 0;
+rb_vm_t *ruby_current_vm = 0;
+rb_event_flag_t ruby_vm_event_flags;
+
+static void thread_free(void *ptr);
+
+void
+rb_vm_inc_const_missing_count(void)
+{
+    ruby_vm_const_missing_count +=1;
+}
+
+/*
+ *  call-seq:
+ *    RubyVM.stat -> Hash
+ *    RubyVM.stat(hsh) -> hsh
+ *    RubyVM.stat(Symbol) -> Numeric
+ *
+ *  Returns a Hash containing implementation-dependent counters inside the VM.
+ *
+ *  This hash includes information about method/constant cache serials:
+ *
+ *    {
+ *      :global_method_state=>251,
+ *      :global_constant_state=>481,
+ *      :class_serial=>9029
+ *    }
+ *
+ *  The contents of the hash are implementation specific and may be changed in
+ *  the future.
+ *
+ *  This method is only expected to work on C Ruby.
+ */
+
+static VALUE
+vm_stat(int argc, VALUE *argv, VALUE self)
+{
+    static VALUE sym_global_method_state, sym_global_constant_state, sym_class_serial;
+    VALUE arg = Qnil;
+    VALUE hash = Qnil, key = Qnil;
+
+    if (rb_scan_args(argc, argv, "01", &arg) == 1) {
+	if (SYMBOL_P(arg))
+	    key = arg;
+	else if (RB_TYPE_P(arg, T_HASH))
+	    hash = arg;
+	else
+	    rb_raise(rb_eTypeError, "non-hash or symbol given");
+    }
+    else if (NIL_P(arg)) {
+	hash = rb_hash_new();
+    }
+
+    if (sym_global_method_state == 0) {
+#define S(s) sym_##s = ID2SYM(rb_intern_const(#s))
+	S(global_method_state);
+	S(global_constant_state);
+	S(class_serial);
+#undef S
+    }
+
+#define SET(name, attr) \
+    if (key == sym_##name) \
+	return SERIALT2NUM(attr); \
+    else if (hash != Qnil) \
+	rb_hash_aset(hash, sym_##name, SERIALT2NUM(attr));
+
+    SET(global_method_state, ruby_vm_global_method_state);
+    SET(global_constant_state, ruby_vm_global_constant_state);
+    SET(class_serial, ruby_vm_class_serial);
+#undef SET
+
+    if (!NIL_P(key)) { /* matched key should return above */
+	rb_raise(rb_eArgError, "unknown key: %"PRIsVALUE, rb_sym2str(key));
+    }
+
+    return hash;
+}
+
+/* control stack frame */
+
+static void
+vm_set_top_stack(rb_thread_t * th, VALUE iseqval)
+{
+    rb_iseq_t *iseq;
+    GetISeqPtr(iseqval, iseq);
+
+    if (iseq->type != ISEQ_TYPE_TOP) {
+	rb_raise(rb_eTypeError, "Not a toplevel InstructionSequence");
+    }
+
+    /* for return */
+    vm_push_frame(th, iseq, VM_FRAME_MAGIC_TOP | VM_FRAME_FLAG_FINISH,
+		  th->top_self, rb_cObject, VM_ENVVAL_BLOCK_PTR(0),
+		  iseq->iseq_encoded, th->cfp->sp, iseq->local_size, 0, iseq->stack_max);
+}
+
+static void
+vm_set_eval_stack(rb_thread_t * th, VALUE iseqval, const NODE *cref, rb_block_t *base_block)
+{
+    rb_iseq_t *iseq;
+    GetISeqPtr(iseqval, iseq);
+
+    vm_push_frame(th, iseq, VM_FRAME_MAGIC_EVAL | VM_FRAME_FLAG_FINISH,
+		  base_block->self, base_block->klass,
+		  VM_ENVVAL_PREV_EP_PTR(base_block->ep), iseq->iseq_encoded,
+		  th->cfp->sp, iseq->local_size, 0, iseq->stack_max);
+
+    if (cref) {
+	th->cfp->ep[-1] = (VALUE)cref;
+    }
+}
+
+static void
+vm_set_main_stack(rb_thread_t *th, VALUE iseqval)
+{
+    VALUE toplevel_binding = rb_const_get(rb_cObject, rb_intern("TOPLEVEL_BINDING"));
+    rb_binding_t *bind;
+    rb_iseq_t *iseq;
+    rb_env_t *env;
+
+    GetBindingPtr(toplevel_binding, bind);
+    GetEnvPtr(bind->env, env);
+    vm_set_eval_stack(th, iseqval, 0, &env->block);
+
+    /* save binding */
+    GetISeqPtr(iseqval, iseq);
+    if (bind && iseq->local_size > 0) {
+	bind->env = rb_vm_make_env_object(th, th->cfp);
+    }
+}
+
+rb_control_frame_t *
+rb_vm_get_binding_creatable_next_cfp(const rb_thread_t *th, const rb_control_frame_t *cfp)
+{
+    while (!RUBY_VM_CONTROL_FRAME_STACK_OVERFLOW_P(th, cfp)) {
+	if (cfp->iseq) {
+	    return (rb_control_frame_t *)cfp;
+	}
+	cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);
+    }
+    return 0;
+}
+
+rb_control_frame_t *
+rb_vm_get_ruby_level_next_cfp(const rb_thread_t *th, const rb_control_frame_t *cfp)
+{
+    while (!RUBY_VM_CONTROL_FRAME_STACK_OVERFLOW_P(th, cfp)) {
+	if (RUBY_VM_NORMAL_ISEQ_P(cfp->iseq)) {
+	    return (rb_control_frame_t *)cfp;
+	}
+	cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);
+    }
+    return 0;
+}
+
+static rb_control_frame_t *
+vm_get_ruby_level_caller_cfp(const rb_thread_t *th, const rb_control_frame_t *cfp)
+{
+    if (RUBY_VM_NORMAL_ISEQ_P(cfp->iseq)) {
+	return (rb_control_frame_t *)cfp;
+    }
+
+    cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);
+
+    while (!RUBY_VM_CONTROL_FRAME_STACK_OVERFLOW_P(th, cfp)) {
+	if (RUBY_VM_NORMAL_ISEQ_P(cfp->iseq)) {
+	    return (rb_control_frame_t *)cfp;
+	}
+
+	if ((cfp->flag & VM_FRAME_FLAG_PASSED) == 0) {
+	    break;
+	}
+	cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);
+    }
+    return 0;
+}
+
+void
+rb_vm_pop_cfunc_frame(void)
+{
+    rb_thread_t *th = GET_THREAD();
+    const rb_method_entry_t *me = th->cfp->me;
+    EXEC_EVENT_HOOK(th, RUBY_EVENT_C_RETURN, th->cfp->self, me->called_id, me->klass, Qnil);
+    RUBY_DTRACE_CMETHOD_RETURN_HOOK(th, me->klass, me->called_id);
+    vm_pop_frame(th);
+}
+
+void
+rb_vm_rewind_cfp(rb_thread_t *th, rb_control_frame_t *cfp)
+{
+    /* check skipped frame */
+    while (th->cfp != cfp) {
+#if VMDEBUG
+	printf("skipped frame: %s\n", vm_frametype_name(th->cfp));
+#endif
+	if (VM_FRAME_TYPE(th->cfp) != VM_FRAME_MAGIC_CFUNC) {
+	    vm_pop_frame(th);
+	}
+	else { /* unlikely path */
+	    rb_vm_pop_cfunc_frame();
+	}
+    }
+}
+
+/* obsolete */
+void
+rb_frame_pop(void)
+{
+    rb_thread_t *th = GET_THREAD();
+    vm_pop_frame(th);
+}
+
+/* at exit */
+
+void
+ruby_vm_at_exit(void (*func)(rb_vm_t *))
+{
+    rb_ary_push((VALUE)&GET_VM()->at_exit, (VALUE)func);
+}
+
+static void
+ruby_vm_run_at_exit_hooks(rb_vm_t *vm)
+{
+    VALUE hook = (VALUE)&vm->at_exit;
+
+    while (RARRAY_LEN(hook) > 0) {
+	typedef void rb_vm_at_exit_func(rb_vm_t*);
+	rb_vm_at_exit_func *func = (rb_vm_at_exit_func*)rb_ary_pop(hook);
+	(*func)(vm);
+    }
+    rb_ary_free(hook);
+}
+
+/* Env */
+
+/*
+  env{
+    env[0] // special (block or prev env)
+    env[1] // env object
+  };
+ */
+
+#define ENV_IN_HEAP_P(th, env)  \
+  (!((th)->stack <= (env) && (env) < ((th)->stack + (th)->stack_size)))
+#define ENV_VAL(env)        ((env)[1])
+
+static void
+env_mark(void * const ptr)
+{
+    const rb_env_t * const env = ptr;
+
+    /* TODO: should mark more restricted range */
+    RUBY_GC_INFO("env->env\n");
+    rb_gc_mark_values((long)env->env_size, env->env);
+
+    RUBY_GC_INFO("env->prev_envval\n");
+    RUBY_MARK_UNLESS_NULL(env->prev_envval);
+    RUBY_MARK_UNLESS_NULL(env->block.self);
+    RUBY_MARK_UNLESS_NULL(env->block.proc);
+
+    if (env->block.iseq) {
+	if (RUBY_VM_IFUNC_P(env->block.iseq)) {
+	    RUBY_MARK_UNLESS_NULL((VALUE)env->block.iseq);
+	}
+	else {
+	    RUBY_MARK_UNLESS_NULL(env->block.iseq->self);
+	}
+    }
+    RUBY_MARK_LEAVE("env");
+}
+
+static size_t
+env_memsize(const void *ptr)
+{
+    const rb_env_t * const env = ptr;
+    size_t size = sizeof(rb_env_t);
+
+    size += (env->env_size - 1) * sizeof(VALUE);
+    return size;
+}
+
+static const rb_data_type_t env_data_type = {
+    "VM/env",
+    {env_mark, RUBY_TYPED_DEFAULT_FREE, env_memsize,},
+    0, 0, RUBY_TYPED_FREE_IMMEDIATELY
+};
+
+static VALUE check_env_value(VALUE envval);
+
+static int
+check_env(rb_env_t * const env)
+{
+    fprintf(stderr, "---\n");
+    fprintf(stderr, "envptr: %p\n", (void *)&env->block.ep[0]);
+    fprintf(stderr, "envval: %10p ", (void *)env->block.ep[1]);
+    dp(env->block.ep[1]);
+    fprintf(stderr, "ep:    %10p\n", (void *)env->block.ep);
+    if (env->prev_envval) {
+	fprintf(stderr, ">>\n");
+	check_env_value(env->prev_envval);
+	fprintf(stderr, "<<\n");
+    }
+    return 1;
+}
+
+static VALUE
+check_env_value(VALUE envval)
+{
+    rb_env_t *env;
+    GetEnvPtr(envval, env);
+
+    if (check_env(env)) {
+	return envval;
+    }
+    rb_bug("invalid env");
+    return Qnil;		/* unreachable */
+}
+
+static VALUE
+vm_make_env_each(const rb_thread_t *const th, rb_control_frame_t *const cfp,
+		 VALUE *envptr, const VALUE *const endptr)
+{
+    VALUE envval, penvval = 0;
+    rb_env_t *env;
+    VALUE *nenvptr;
+    int i, local_size;
+
+    if (ENV_IN_HEAP_P(th, envptr)) {
+	return ENV_VAL(envptr);
+    }
+
+    if (envptr != endptr) {
+	VALUE *penvptr = GC_GUARDED_PTR_REF(*envptr);
+	rb_control_frame_t *pcfp = cfp;
+
+	if (ENV_IN_HEAP_P(th, penvptr)) {
+	    penvval = ENV_VAL(penvptr);
+	}
+	else {
+	    while (pcfp->ep != penvptr) {
+		pcfp++;
+		if (pcfp->ep == 0) {
+		    SDR();
+		    rb_bug("invalid ep");
+		}
+	    }
+	    penvval = vm_make_env_each(th, pcfp, penvptr, endptr);
+	    *envptr = VM_ENVVAL_PREV_EP_PTR(pcfp->ep);
+	}
+    }
+
+    if (!RUBY_VM_NORMAL_ISEQ_P(cfp->iseq)) {
+	local_size = 2;
+    }
+    else {
+	local_size = cfp->iseq->local_size;
+    }
+
+    /* allocate env */
+    env = xmalloc(sizeof(rb_env_t) + ((local_size + 1) * sizeof(VALUE)));
+    env->env_size = local_size + 1 + 1;
+    env->local_size = local_size;
+
+    for (i = 0; i <= local_size; i++) {
+	env->env[i] = envptr[-local_size + i];
+#if 0
+	fprintf(stderr, "%2d ", &envptr[-local_size + i] - th->stack); dp(env->env[i]);
+	if (RUBY_VM_NORMAL_ISEQ_P(cfp->iseq)) {
+	    /* clear value stack for GC */
+	    envptr[-local_size + i] = 0;
+	}
+#endif
+    }
+
+    /* be careful not to trigger GC after this */
+    envval = TypedData_Wrap_Struct(rb_cEnv, &env_data_type, env);
+
+   /*
+    * must happen after TypedData_Wrap_Struct to ensure penvval is markable
+    * in case object allocation triggers GC and clobbers penvval.
+    */
+    env->prev_envval = penvval;
+
+    *envptr = envval;		/* GC mark */
+    nenvptr = &env->env[i - 1];
+    nenvptr[1] = envval;	/* frame self */
+
+    /* reset ep in cfp */
+    cfp->ep = nenvptr;
+
+    /* as Binding */
+    env->block.self = cfp->self;
+    env->block.klass = 0;
+    env->block.ep = cfp->ep;
+    env->block.iseq = cfp->iseq;
+    env->block.proc = 0;
+
+    if (!RUBY_VM_NORMAL_ISEQ_P(cfp->iseq)) {
+	/* TODO */
+	env->block.iseq = 0;
+    }
+    return envval;
+}
+
+static int
+collect_local_variables_in_iseq(const rb_iseq_t *iseq, const struct local_var_list *vars)
+{
+    int i;
+    if (!iseq) return 0;
+    for (i = 0; i < iseq->local_table_size; i++) {
+	local_var_list_add(vars, iseq->local_table[i]);
+    }
+    return 1;
+}
+
+static void
+collect_local_variables_in_env(const rb_env_t *env, const struct local_var_list *vars)
+{
+
+    while (collect_local_variables_in_iseq(env->block.iseq, vars),
+	   env->prev_envval) {
+	GetEnvPtr(env->prev_envval, env);
+    }
+}
+
+static int
+vm_collect_local_variables_in_heap(rb_thread_t *th, const VALUE *ep, const struct local_var_list *vars)
+{
+    if (ENV_IN_HEAP_P(th, ep)) {
+	rb_env_t *env;
+	GetEnvPtr(ENV_VAL(ep), env);
+	collect_local_variables_in_env(env, vars);
+	return 1;
+    }
+    else {
+	return 0;
+    }
+}
+
+VALUE
+rb_vm_env_local_variables(VALUE envval)
+{
+    struct local_var_list vars;
+    const rb_env_t *env;
+
+    GetEnvPtr(envval, env);
+    local_var_list_init(&vars);
+    collect_local_variables_in_env(env, &vars);
+    return local_var_list_finish(&vars);
+}
+
+static VALUE vm_make_proc_from_block(rb_thread_t *th, rb_block_t *block);
+static VALUE vm_make_env_object(rb_thread_t * th, rb_control_frame_t *cfp, VALUE *blockprocptr);
+
+VALUE
+rb_vm_make_env_object(rb_thread_t * th, rb_control_frame_t *cfp)
+{
+    VALUE blockprocval;
+    return vm_make_env_object(th, cfp, &blockprocval);
+}
+
+static VALUE
+vm_make_env_object(rb_thread_t *th, rb_control_frame_t *cfp, VALUE *blockprocptr)
+{
+    VALUE envval;
+    VALUE *lep = VM_CF_LEP(cfp);
+    rb_block_t *blockptr = VM_EP_BLOCK_PTR(lep);
+
+    if (blockptr) {
+	VALUE blockprocval = vm_make_proc_from_block(th, blockptr);
+	rb_proc_t *p;
+	GetProcPtr(blockprocval, p);
+	lep[0] = VM_ENVVAL_BLOCK_PTR(&p->block);
+	*blockprocptr = blockprocval;
+    }
+
+    envval = vm_make_env_each(th, cfp, cfp->ep, lep);
+
+    if (PROCDEBUG) {
+	check_env_value(envval);
+    }
+
+    return envval;
+}
+
+void
+rb_vm_stack_to_heap(rb_thread_t *th)
+{
+    rb_control_frame_t *cfp = th->cfp;
+    while ((cfp = rb_vm_get_binding_creatable_next_cfp(th, cfp)) != 0) {
+	rb_vm_make_env_object(th, cfp);
+	cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);
+    }
+}
+
+/* Proc */
+
+static VALUE
+vm_make_proc_from_block(rb_thread_t *th, rb_block_t *block)
+{
+    if (!block->proc) {
+	block->proc = rb_vm_make_proc(th, block, rb_cProc);
+    }
+    return block->proc;
+}
+
+static inline VALUE
+rb_proc_alloc(VALUE klass, const rb_block_t *block,
+		VALUE envval, VALUE blockprocval,
+		int8_t safe_level, int8_t is_from_method, int8_t is_lambda)
+{
+    VALUE procval;
+    rb_proc_t *proc = ALLOC(rb_proc_t);
+
+    proc->block = *block;
+    proc->safe_level = safe_level;
+    proc->is_from_method = is_from_method;
+    proc->is_lambda = is_lambda;
+
+    procval = rb_proc_wrap(klass, proc);
+
+    /*
+     * ensure VALUEs are markable here as rb_proc_wrap may trigger allocation
+     * and clobber envval + blockprocval
+     */
+    proc->envval = envval;
+    proc->blockprocval = blockprocval;
+
+    return procval;
+}
+
+VALUE
+rb_vm_make_proc(rb_thread_t *th, const rb_block_t *block, VALUE klass)
+{
+    return rb_vm_make_proc_lambda(th, block, klass, 0);
+}
+
+VALUE
+rb_vm_make_proc_lambda(rb_thread_t *th, const rb_block_t *block, VALUE klass, int8_t is_lambda)
+{
+    VALUE procval, envval, blockprocval = 0;
+    rb_control_frame_t *cfp = RUBY_VM_GET_CFP_FROM_BLOCK_PTR(block);
+
+    if (block->proc) {
+	rb_bug("rb_vm_make_proc: Proc value is already created.");
+    }
+
+    envval = vm_make_env_object(th, cfp, &blockprocval);
+
+    if (PROCDEBUG) {
+	check_env_value(envval);
+    }
+
+    procval = rb_proc_alloc(klass, block, envval, blockprocval,
+			    (int8_t)th->safe_level, 0, is_lambda);
+
+    if (VMDEBUG) {
+	if (th->stack < block->ep && block->ep < th->stack + th->stack_size) {
+	    rb_bug("invalid ptr: block->ep");
+	}
+    }
+
+    return procval;
+}
+
+/* Binding */
+
+VALUE
+rb_vm_make_binding(rb_thread_t *th, const rb_control_frame_t *src_cfp)
+{
+    rb_control_frame_t *cfp = rb_vm_get_binding_creatable_next_cfp(th, src_cfp);
+    rb_control_frame_t *ruby_level_cfp = rb_vm_get_ruby_level_next_cfp(th, src_cfp);
+    VALUE bindval, envval;
+    rb_binding_t *bind;
+    VALUE blockprocval = 0;
+
+    if (cfp == 0 || ruby_level_cfp == 0) {
+	rb_raise(rb_eRuntimeError, "Can't create Binding Object on top of Fiber.");
+    }
+
+    while (1) {
+	envval = vm_make_env_object(th, cfp, &blockprocval);
+	if (cfp == ruby_level_cfp) {
+	    break;
+	}
+	cfp = rb_vm_get_binding_creatable_next_cfp(th, RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp));
+    }
+
+    bindval = rb_binding_alloc(rb_cBinding);
+    GetBindingPtr(bindval, bind);
+    bind->env = envval;
+    bind->path = ruby_level_cfp->iseq->location.path;
+    bind->blockprocval = blockprocval;
+    bind->first_lineno = rb_vm_get_sourceline(ruby_level_cfp);
+
+    return bindval;
+}
+
+VALUE *
+rb_binding_add_dynavars(rb_binding_t *bind, int dyncount, const ID *dynvars)
+{
+    VALUE envval = bind->env, path = bind->path, iseqval;
+    rb_env_t *env;
+    rb_block_t *base_block;
+    rb_thread_t *th = GET_THREAD();
+    rb_iseq_t *base_iseq;
+    NODE *node = 0;
+    ID minibuf[4], *dyns = minibuf;
+    VALUE idtmp = 0;
+    VALUE blockprocval = 0;
+
+    if (dyncount < 0) return 0;
+
+    GetEnvPtr(envval, env);
+
+    base_block = &env->block;
+    base_iseq = base_block->iseq;
+
+    if (dyncount >= numberof(minibuf)) dyns = ALLOCV_N(ID, idtmp, dyncount + 1);
+
+    dyns[0] = dyncount;
+    MEMCPY(dyns + 1, dynvars, ID, dyncount);
+    node = NEW_NODE(NODE_SCOPE, dyns, 0, 0);
+
+    iseqval = rb_iseq_new(node, base_iseq->location.label, path, path,
+			  base_iseq->self, ISEQ_TYPE_EVAL);
+    node->u1.tbl = 0; /* reset table */
+    ALLOCV_END(idtmp);
+
+    vm_set_eval_stack(th, iseqval, 0, base_block);
+    bind->env = vm_make_env_object(th, th->cfp, &blockprocval);
+    bind->blockprocval = blockprocval;
+    vm_pop_frame(th);
+    GetEnvPtr(bind->env, env);
+
+    return env->env;
+}
+
+/* C -> Ruby: block */
+
+static inline VALUE
+invoke_block_from_c(rb_thread_t *th, const rb_block_t *block,
+		    VALUE self, int argc, const VALUE *argv,
+		    const rb_block_t *blockptr, const NODE *cref,
+		    VALUE defined_class, int splattable)
+{
+    if (SPECIAL_CONST_P(block->iseq)) {
+	return Qnil;
+    }
+    else if (!RUBY_VM_IFUNC_P(block->iseq)) {
+	VALUE ret;
+	const rb_iseq_t *iseq = block->iseq;
+	const rb_control_frame_t *cfp;
+	int i, opt_pc, arg_size = iseq->param.size;
+	int type = block_proc_is_lambda(block->proc) ? VM_FRAME_MAGIC_LAMBDA : VM_FRAME_MAGIC_BLOCK;
+	const rb_method_entry_t *me = th->passed_bmethod_me;
+	th->passed_bmethod_me = 0;
+	cfp = th->cfp;
+
+	for (i=0; i<argc; i++) {
+	    cfp->sp[i] = argv[i];
+	}
+
+	opt_pc = vm_yield_setup_args(th, iseq, argc, cfp->sp, blockptr,
+				     (type == VM_FRAME_MAGIC_LAMBDA ? (splattable ? arg_setup_lambda : arg_setup_method) : arg_setup_block));
+
+	if (me != 0) {
+	    /* bmethod */
+	    vm_push_frame(th, iseq, type | VM_FRAME_FLAG_FINISH | VM_FRAME_FLAG_BMETHOD,
+			  self, defined_class,
+			  VM_ENVVAL_PREV_EP_PTR(block->ep),
+			  iseq->iseq_encoded + opt_pc,
+			  cfp->sp + arg_size, iseq->local_size - arg_size,
+			  me, iseq->stack_max);
+
+	    RUBY_DTRACE_METHOD_ENTRY_HOOK(th, me->klass, me->called_id);
+	    EXEC_EVENT_HOOK(th, RUBY_EVENT_CALL, self, me->called_id, me->klass, Qnil);
+	}
+	else {
+	    vm_push_frame(th, iseq, type | VM_FRAME_FLAG_FINISH,
+			  self, defined_class,
+			  VM_ENVVAL_PREV_EP_PTR(block->ep),
+			  iseq->iseq_encoded + opt_pc,
+			  cfp->sp + arg_size, iseq->local_size - arg_size,
+			  0, iseq->stack_max);
+	}
+
+	if (cref) {
+	    th->cfp->ep[-1] = (VALUE)cref;
+	}
+
+	ret = vm_exec(th);
+
+	if (me) {
+	    /* bmethod */
+	    EXEC_EVENT_HOOK(th, RUBY_EVENT_RETURN, self, me->called_id, me->klass, ret);
+	    RUBY_DTRACE_METHOD_RETURN_HOOK(th, me->klass, me->called_id);
+	}
+
+	return ret;
+    }
+    else {
+	return vm_yield_with_cfunc(th, block, self, defined_class,
+				   argc, argv, blockptr);
+    }
+}
+
+static inline const rb_block_t *
+check_block(rb_thread_t *th)
+{
+    const rb_block_t *blockptr = VM_CF_BLOCK_PTR(th->cfp);
+
+    if (blockptr == 0) {
+	rb_vm_localjump_error("no block given", Qnil, 0);
+    }
+
+    return blockptr;
+}
+
+static inline VALUE
+vm_yield_with_cref(rb_thread_t *th, int argc, const VALUE *argv, const NODE *cref)
+{
+    const rb_block_t *blockptr = check_block(th);
+    return invoke_block_from_c(th, blockptr, blockptr->self, argc, argv, 0, cref,
+			       blockptr->klass, 1);
+}
+
+static inline VALUE
+vm_yield(rb_thread_t *th, int argc, const VALUE *argv)
+{
+    const rb_block_t *blockptr = check_block(th);
+    return invoke_block_from_c(th, blockptr, blockptr->self, argc, argv, 0, 0,
+			       blockptr->klass, 1);
+}
+
+static inline VALUE
+vm_yield_with_block(rb_thread_t *th, int argc, const VALUE *argv, const rb_block_t *blockargptr)
+{
+    const rb_block_t *blockptr = check_block(th);
+    return invoke_block_from_c(th, blockptr, blockptr->self, argc, argv, blockargptr, 0,
+			       blockptr->klass, 1);
+}
+
+static VALUE
+vm_invoke_proc(rb_thread_t *th, rb_proc_t *proc, VALUE self, VALUE defined_class,
+	       int argc, const VALUE *argv, const rb_block_t *blockptr)
+{
+    VALUE val = Qundef;
+    int state;
+    volatile int stored_safe = th->safe_level;
+
+    TH_PUSH_TAG(th);
+    if ((state = EXEC_TAG()) == 0) {
+	if (!proc->is_from_method) {
+	    th->safe_level = proc->safe_level;
+	}
+	val = invoke_block_from_c(th, &proc->block, self, argc, argv, blockptr, 0,
+				  defined_class, 0);
+    }
+    TH_POP_TAG();
+
+    if (!proc->is_from_method) {
+	th->safe_level = stored_safe;
+    }
+
+    if (state) {
+	JUMP_TAG(state);
+    }
+    return val;
+}
+
+VALUE
+rb_vm_invoke_proc(rb_thread_t *th, rb_proc_t *proc,
+		  int argc, const VALUE *argv, const rb_block_t *blockptr)
+{
+    return vm_invoke_proc(th, proc, proc->block.self, proc->block.klass,
+			  argc, argv, blockptr);
+}
+
+/* special variable */
+
+static rb_control_frame_t *
+vm_normal_frame(rb_thread_t *th, rb_control_frame_t *cfp)
+{
+    while (cfp->pc == 0) {
+	cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);
+	if (RUBY_VM_CONTROL_FRAME_STACK_OVERFLOW_P(th, cfp)) {
+	    return 0;
+	}
+    }
+    return cfp;
+}
+
+static VALUE
+vm_cfp_svar_get(rb_thread_t *th, rb_control_frame_t *cfp, VALUE key)
+{
+    cfp = vm_normal_frame(th, cfp);
+    return lep_svar_get(th, cfp ? VM_CF_LEP(cfp) : 0, key);
+}
+
+static void
+vm_cfp_svar_set(rb_thread_t *th, rb_control_frame_t *cfp, VALUE key, const VALUE val)
+{
+    cfp = vm_normal_frame(th, cfp);
+    lep_svar_set(th, cfp ? VM_CF_LEP(cfp) : 0, key, val);
+}
+
+static VALUE
+vm_svar_get(VALUE key)
+{
+    rb_thread_t *th = GET_THREAD();
+    return vm_cfp_svar_get(th, th->cfp, key);
+}
+
+static void
+vm_svar_set(VALUE key, VALUE val)
+{
+    rb_thread_t *th = GET_THREAD();
+    vm_cfp_svar_set(th, th->cfp, key, val);
+}
+
+VALUE
+rb_backref_get(void)
+{
+    return vm_svar_get(1);
+}
+
+void
+rb_backref_set(VALUE val)
+{
+    vm_svar_set(1, val);
+}
+
+VALUE
+rb_lastline_get(void)
+{
+    return vm_svar_get(0);
+}
+
+void
+rb_lastline_set(VALUE val)
+{
+    vm_svar_set(0, val);
+}
+
+/* misc */
+
+VALUE
+rb_sourcefilename(void)
+{
+    rb_thread_t *th = GET_THREAD();
+    rb_control_frame_t *cfp = rb_vm_get_ruby_level_next_cfp(th, th->cfp);
+
+    if (cfp) {
+	return cfp->iseq->location.path;
+    }
+    else {
+	return Qnil;
+    }
+}
+
+const char *
+rb_sourcefile(void)
+{
+    rb_thread_t *th = GET_THREAD();
+    rb_control_frame_t *cfp = rb_vm_get_ruby_level_next_cfp(th, th->cfp);
+
+    if (cfp) {
+	return RSTRING_PTR(cfp->iseq->location.path);
+    }
+    else {
+	return 0;
+    }
+}
+
+int
+rb_sourceline(void)
+{
+    rb_thread_t *th = GET_THREAD();
+    rb_control_frame_t *cfp = rb_vm_get_ruby_level_next_cfp(th, th->cfp);
+
+    if (cfp) {
+	return rb_vm_get_sourceline(cfp);
+    }
+    else {
+	return 0;
+    }
+}
+
+NODE *
+rb_vm_cref(void)
+{
+    rb_thread_t *th = GET_THREAD();
+    rb_control_frame_t *cfp = rb_vm_get_ruby_level_next_cfp(th, th->cfp);
+
+    if (cfp == 0) {
+	return NULL;
+    }
+    return rb_vm_get_cref(cfp->iseq, cfp->ep);
+}
+
+const NODE *
+rb_vm_cref_in_context(VALUE self, VALUE cbase)
+{
+    rb_thread_t *th = GET_THREAD();
+    const rb_control_frame_t *cfp = rb_vm_get_ruby_level_next_cfp(th, th->cfp);
+    const NODE *cref;
+    if (cfp->self != self) return NULL;
+    cref = rb_vm_get_cref(cfp->iseq, cfp->ep);
+    if (cref->nd_clss != cbase) return NULL;
+    return cref;
+}
+
+#if 0
+void
+debug_cref(NODE *cref)
+{
+    while (cref) {
+	dp(cref->nd_clss);
+	printf("%ld\n", cref->nd_visi);
+	cref = cref->nd_next;
+    }
+}
+#endif
+
+VALUE
+rb_vm_cbase(void)
+{
+    rb_thread_t *th = GET_THREAD();
+    rb_control_frame_t *cfp = rb_vm_get_ruby_level_next_cfp(th, th->cfp);
+
+    if (cfp == 0) {
+	rb_raise(rb_eRuntimeError, "Can't call on top of Fiber or Thread");
+    }
+    return vm_get_cbase(cfp->iseq, cfp->ep);
+}
+
+/* jump */
+
+static VALUE
+make_localjump_error(const char *mesg, VALUE value, int reason)
+{
+    extern VALUE rb_eLocalJumpError;
+    VALUE exc = rb_exc_new2(rb_eLocalJumpError, mesg);
+    ID id;
+
+    switch (reason) {
+      case TAG_BREAK:
+	CONST_ID(id, "break");
+	break;
+      case TAG_REDO:
+	CONST_ID(id, "redo");
+	break;
+      case TAG_RETRY:
+	CONST_ID(id, "retry");
+	break;
+      case TAG_NEXT:
+	CONST_ID(id, "next");
+	break;
+      case TAG_RETURN:
+	CONST_ID(id, "return");
+	break;
+      default:
+	CONST_ID(id, "noreason");
+	break;
+    }
+    rb_iv_set(exc, "@exit_value", value);
+    rb_iv_set(exc, "@reason", ID2SYM(id));
+    return exc;
+}
+
+void
+rb_vm_localjump_error(const char *mesg, VALUE value, int reason)
+{
+    VALUE exc = make_localjump_error(mesg, value, reason);
+    rb_exc_raise(exc);
+}
+
+VALUE
+rb_vm_make_jump_tag_but_local_jump(int state, VALUE val)
+{
+    VALUE result = Qnil;
+
+    if (val == Qundef) {
+	val = GET_THREAD()->tag->retval;
+    }
+    switch (state) {
+      case 0:
+	break;
+      case TAG_RETURN:
+	result = make_localjump_error("unexpected return", val, state);
+	break;
+      case TAG_BREAK:
+	result = make_localjump_error("unexpected break", val, state);
+	break;
+      case TAG_NEXT:
+	result = make_localjump_error("unexpected next", val, state);
+	break;
+      case TAG_REDO:
+	result = make_localjump_error("unexpected redo", Qnil, state);
+	break;
+      case TAG_RETRY:
+	result = make_localjump_error("retry outside of rescue clause", Qnil, state);
+	break;
+      default:
+	break;
+    }
+    return result;
+}
+
+void
+rb_vm_jump_tag_but_local_jump(int state)
+{
+    VALUE exc = rb_vm_make_jump_tag_but_local_jump(state, Qundef);
+    if (!NIL_P(exc)) rb_exc_raise(exc);
+    JUMP_TAG(state);
+}
+
+NORETURN(static void vm_iter_break(rb_thread_t *th, VALUE val));
+
+static void
+vm_iter_break(rb_thread_t *th, VALUE val)
+{
+    rb_control_frame_t *cfp = th->cfp;
+    VALUE *ep = VM_CF_PREV_EP(cfp);
+    rb_control_frame_t *target_cfp = rb_vm_search_cf_from_ep(th, cfp, ep);
+
+#if 0				/* raise LocalJumpError */
+    if (!target_cfp) {
+	rb_vm_localjump_error("unexpected break", val, TAG_BREAK);
+    }
+#endif
+
+    th->state = TAG_BREAK;
+    th->errinfo = (VALUE)NEW_THROW_OBJECT(val, (VALUE)target_cfp, TAG_BREAK);
+    TH_JUMP_TAG(th, TAG_BREAK);
+}
+
+void
+rb_iter_break(void)
+{
+    vm_iter_break(GET_THREAD(), Qnil);
+}
+
+void
+rb_iter_break_value(VALUE val)
+{
+    vm_iter_break(GET_THREAD(), val);
+}
+
+/* optimization: redefine management */
+
+static st_table *vm_opt_method_table = 0;
+
+static int
+vm_redefinition_check_flag(VALUE klass)
+{
+    if (klass == rb_cFixnum) return FIXNUM_REDEFINED_OP_FLAG;
+    if (klass == rb_cFloat)  return FLOAT_REDEFINED_OP_FLAG;
+    if (klass == rb_cString) return STRING_REDEFINED_OP_FLAG;
+    if (klass == rb_cArray)  return ARRAY_REDEFINED_OP_FLAG;
+    if (klass == rb_cHash)   return HASH_REDEFINED_OP_FLAG;
+    if (klass == rb_cBignum) return BIGNUM_REDEFINED_OP_FLAG;
+    if (klass == rb_cSymbol) return SYMBOL_REDEFINED_OP_FLAG;
+    if (klass == rb_cTime)   return TIME_REDEFINED_OP_FLAG;
+    if (klass == rb_cRegexp) return REGEXP_REDEFINED_OP_FLAG;
+    return 0;
+}
+
+static void
+rb_vm_check_redefinition_opt_method(const rb_method_entry_t *me, VALUE klass)
+{
+    st_data_t bop;
+    if (!me->def || me->def->type == VM_METHOD_TYPE_CFUNC) {
+	if (st_lookup(vm_opt_method_table, (st_data_t)me, &bop)) {
+	    int flag = vm_redefinition_check_flag(klass);
+
+	    ruby_vm_redefined_flag[bop] |= flag;
+	}
+    }
+}
+
+static int
+check_redefined_method(st_data_t key, st_data_t value, st_data_t data)
+{
+    ID mid = (ID)key;
+    rb_method_entry_t *me = (rb_method_entry_t *)value;
+    VALUE klass = (VALUE)data;
+    rb_method_entry_t *newme = rb_method_entry(klass, mid, NULL);
+
+    if (newme != me)
+	rb_vm_check_redefinition_opt_method(me, me->klass);
+    return ST_CONTINUE;
+}
+
+void
+rb_vm_check_redefinition_by_prepend(VALUE klass)
+{
+    if (!vm_redefinition_check_flag(klass)) return;
+    st_foreach(RCLASS_M_TBL(RCLASS_ORIGIN(klass)), check_redefined_method,
+	       (st_data_t)klass);
+}
+
+static void
+add_opt_method(VALUE klass, ID mid, VALUE bop)
+{
+    rb_method_entry_t *me = rb_method_entry_at(klass, mid);
+
+    if (me && me->def &&
+	me->def->type == VM_METHOD_TYPE_CFUNC) {
+	st_insert(vm_opt_method_table, (st_data_t)me, (st_data_t)bop);
+    }
+    else {
+	rb_bug("undefined optimized method: %s", rb_id2name(mid));
+    }
+}
+
+static void
+vm_init_redefined_flag(void)
+{
+    ID mid;
+    VALUE bop;
+
+    vm_opt_method_table = st_init_numtable();
+
+#define OP(mid_, bop_) (mid = id##mid_, bop = BOP_##bop_, ruby_vm_redefined_flag[bop] = 0)
+#define C(k) add_opt_method(rb_c##k, mid, bop)
+    OP(PLUS, PLUS), (C(Fixnum), C(Float), C(String), C(Array));
+    OP(MINUS, MINUS), (C(Fixnum), C(Float));
+    OP(MULT, MULT), (C(Fixnum), C(Float));
+    OP(DIV, DIV), (C(Fixnum), C(Float));
+    OP(MOD, MOD), (C(Fixnum), C(Float));
+    OP(Eq, EQ), (C(Fixnum), C(Float), C(String));
+    OP(Eqq, EQQ), (C(Fixnum), C(Bignum), C(Float), C(Symbol), C(String));
+    OP(LT, LT), (C(Fixnum), C(Float));
+    OP(LE, LE), (C(Fixnum), C(Float));
+    OP(GT, GT), (C(Fixnum), C(Float));
+    OP(GE, GE), (C(Fixnum), C(Float));
+    OP(LTLT, LTLT), (C(String), C(Array));
+    OP(AREF, AREF), (C(Array), C(Hash));
+    OP(ASET, ASET), (C(Array), C(Hash));
+    OP(Length, LENGTH), (C(Array), C(String), C(Hash));
+    OP(Size, SIZE), (C(Array), C(String), C(Hash));
+    OP(EmptyP, EMPTY_P), (C(Array), C(String), C(Hash));
+    OP(Succ, SUCC), (C(Fixnum), C(String), C(Time));
+    OP(EqTilde, MATCH), (C(Regexp), C(String));
+    OP(Freeze, FREEZE), (C(String));
+#undef C
+#undef OP
+}
+
+/* for vm development */
+
+#if VMDEBUG
+static const char *
+vm_frametype_name(const rb_control_frame_t *cfp)
+{
+    switch (VM_FRAME_TYPE(cfp)) {
+      case VM_FRAME_MAGIC_METHOD: return "method";
+      case VM_FRAME_MAGIC_BLOCK:  return "block";
+      case VM_FRAME_MAGIC_CLASS:  return "class";
+      case VM_FRAME_MAGIC_TOP:    return "top";
+      case VM_FRAME_MAGIC_CFUNC:  return "cfunc";
+      case VM_FRAME_MAGIC_PROC:   return "proc";
+      case VM_FRAME_MAGIC_IFUNC:  return "ifunc";
+      case VM_FRAME_MAGIC_EVAL:   return "eval";
+      case VM_FRAME_MAGIC_LAMBDA: return "lambda";
+      case VM_FRAME_MAGIC_RESCUE: return "rescue";
+      default:
+	rb_bug("unknown frame");
+    }
+}
+#endif
+
+static void
+hook_before_rewind(rb_thread_t *th, rb_control_frame_t *cfp)
+{
+    switch (VM_FRAME_TYPE(th->cfp)) {
+      case VM_FRAME_MAGIC_METHOD:
+	RUBY_DTRACE_METHOD_RETURN_HOOK(th, 0, 0);
+	EXEC_EVENT_HOOK_AND_POP_FRAME(th, RUBY_EVENT_RETURN, th->cfp->self, 0, 0, Qnil);
+	break;
+      case VM_FRAME_MAGIC_BLOCK:
+      case VM_FRAME_MAGIC_LAMBDA:
+	if (VM_FRAME_TYPE_BMETHOD_P(th->cfp)) {
+	    EXEC_EVENT_HOOK(th, RUBY_EVENT_B_RETURN, th->cfp->self, 0, 0, Qnil);
+	    EXEC_EVENT_HOOK_AND_POP_FRAME(th, RUBY_EVENT_RETURN, th->cfp->self, th->cfp->me->called_id, th->cfp->me->klass, Qnil);
+	}
+	else {
+	    EXEC_EVENT_HOOK_AND_POP_FRAME(th, RUBY_EVENT_B_RETURN, th->cfp->self, 0, 0, Qnil);
+	}
+	break;
+      case VM_FRAME_MAGIC_CLASS:
+	EXEC_EVENT_HOOK_AND_POP_FRAME(th, RUBY_EVENT_END, th->cfp->self, 0, 0, Qnil);
+	break;
+    }
+}
+
+/* evaluator body */
+
+/*                  finish
+  VMe (h1)          finish
+    VM              finish F1 F2
+      cfunc         finish F1 F2 C1
+        rb_funcall  finish F1 F2 C1
+          VMe       finish F1 F2 C1
+            VM      finish F1 F2 C1 F3
+
+  F1 - F3 : pushed by VM
+  C1      : pushed by send insn (CFUNC)
+
+  struct CONTROL_FRAME {
+    VALUE *pc;                  // cfp[0], program counter
+    VALUE *sp;                  // cfp[1], stack pointer
+    VALUE *bp;                  // cfp[2], base pointer
+    rb_iseq_t *iseq;            // cfp[3], iseq
+    VALUE flag;                 // cfp[4], magic
+    VALUE self;                 // cfp[5], self
+    VALUE *ep;                  // cfp[6], env pointer
+    rb_iseq_t * block_iseq;     // cfp[7], block iseq
+    VALUE proc;                 // cfp[8], always 0
+  };
+
+  struct BLOCK {
+    VALUE self;
+    VALUE *ep;
+    rb_iseq_t *block_iseq;
+    VALUE proc;
+  };
+
+  struct METHOD_CONTROL_FRAME {
+    rb_control_frame_t frame;
+  };
+
+  struct METHOD_FRAME {
+    VALUE arg0;
+    ...
+    VALUE argM;
+    VALUE param0;
+    ...
+    VALUE paramN;
+    VALUE cref;
+    VALUE special;                         // lep [1]
+    struct block_object *block_ptr | 0x01; // lep [0]
+  };
+
+  struct BLOCK_CONTROL_FRAME {
+    rb_control_frame_t frame;
+  };
+
+  struct BLOCK_FRAME {
+    VALUE arg0;
+    ...
+    VALUE argM;
+    VALUE param0;
+    ...
+    VALUE paramN;
+    VALUE cref;
+    VALUE *(prev_ptr | 0x01); // ep[0]
+  };
+
+  struct CLASS_CONTROL_FRAME {
+    rb_control_frame_t frame;
+  };
+
+  struct CLASS_FRAME {
+    VALUE param0;
+    ...
+    VALUE paramN;
+    VALUE cref;
+    VALUE prev_ep; // for frame jump
+  };
+
+  struct C_METHOD_CONTROL_FRAME {
+    VALUE *pc;                       // 0
+    VALUE *sp;                       // stack pointer
+    VALUE *bp;                       // base pointer (used in exception)
+    rb_iseq_t *iseq;                 // cmi
+    VALUE magic;                     // C_METHOD_FRAME
+    VALUE self;                      // ?
+    VALUE *ep;                       // ep == lep
+    rb_iseq_t * block_iseq;          //
+    VALUE proc;                      // always 0
+  };
+
+  struct C_BLOCK_CONTROL_FRAME {
+    VALUE *pc;                       // point only "finish" insn
+    VALUE *sp;                       // sp
+    rb_iseq_t *iseq;                 // ?
+    VALUE magic;                     // C_METHOD_FRAME
+    VALUE self;                      // needed?
+    VALUE *ep;                       // ep
+    rb_iseq_t * block_iseq; // 0
+  };
+ */
+
+static VALUE
+vm_exec(rb_thread_t *th)
+{
+    int state;
+    VALUE result, err;
+    VALUE initial = 0;
+
+    TH_PUSH_TAG(th);
+    _tag.retval = Qnil;
+    if ((state = EXEC_TAG()) == 0) {
+      vm_loop_start:
+	result = vm_exec_core(th, initial);
+	if ((state = th->state) != 0) {
+	    err = result;
+	    th->state = 0;
+	    goto exception_handler;
+	}
+    }
+    else {
+	int i;
+	struct iseq_catch_table_entry *entry;
+	struct iseq_catch_table *ct;
+	unsigned long epc, cont_pc, cont_sp;
+	VALUE catch_iseqval;
+	rb_control_frame_t *cfp;
+	VALUE type;
+	rb_control_frame_t *escape_cfp;
+
+	err = th->errinfo;
+
+      exception_handler:
+	cont_pc = cont_sp = catch_iseqval = 0;
+
+	while (th->cfp->pc == 0 || th->cfp->iseq == 0) {
+	    if (UNLIKELY(VM_FRAME_TYPE(th->cfp) == VM_FRAME_MAGIC_CFUNC)) {
+		const rb_method_entry_t *me = th->cfp->me;
+		EXEC_EVENT_HOOK(th, RUBY_EVENT_C_RETURN, th->cfp->self, me->called_id, me->klass, Qnil);
+		RUBY_DTRACE_METHOD_RETURN_HOOK(th, me->klass, me->called_id);
+	    }
+	    th->cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(th->cfp);
+	}
+
+	cfp = th->cfp;
+	epc = cfp->pc - cfp->iseq->iseq_encoded;
+
+	escape_cfp = NULL;
+	if (state == TAG_BREAK || state == TAG_RETURN) {
+	    escape_cfp = GET_THROWOBJ_CATCH_POINT(err);
+
+	    if (cfp == escape_cfp) {
+		if (state == TAG_RETURN) {
+		    if (!VM_FRAME_TYPE_FINISH_P(cfp)) {
+			SET_THROWOBJ_CATCH_POINT(err, (VALUE)(cfp + 1));
+			SET_THROWOBJ_STATE(err, state = TAG_BREAK);
+		    }
+		    else {
+			ct = cfp->iseq->catch_table;
+			if (ct) for (i = 0; i < ct->size; i++) {
+			    entry = &ct->entries[i];
+			    if (entry->start < epc && entry->end >= epc) {
+				if (entry->type == CATCH_TYPE_ENSURE) {
+				    catch_iseqval = entry->iseq;
+				    cont_pc = entry->cont;
+				    cont_sp = entry->sp;
+				    break;
+				}
+			    }
+			}
+			if (!catch_iseqval) {
+			    th->errinfo = Qnil;
+			    result = GET_THROWOBJ_VAL(err);
+			    hook_before_rewind(th, th->cfp);
+			    vm_pop_frame(th);
+			    goto finish_vme;
+			}
+		    }
+		    /* through */
+		}
+		else {
+		    /* TAG_BREAK */
+#if OPT_STACK_CACHING
+		    initial = (GET_THROWOBJ_VAL(err));
+#else
+		    *th->cfp->sp++ = (GET_THROWOBJ_VAL(err));
+#endif
+		    th->errinfo = Qnil;
+		    goto vm_loop_start;
+		}
+	    }
+	}
+
+	if (state == TAG_RAISE) {
+	    ct = cfp->iseq->catch_table;
+	    if (ct) for (i = 0; i < ct->size; i++) {
+		entry = &ct->entries[i];
+		if (entry->start < epc && entry->end >= epc) {
+
+		    if (entry->type == CATCH_TYPE_RESCUE ||
+			entry->type == CATCH_TYPE_ENSURE) {
+			catch_iseqval = entry->iseq;
+			cont_pc = entry->cont;
+			cont_sp = entry->sp;
+			break;
+		    }
+		}
+	    }
+	}
+	else if (state == TAG_RETRY) {
+	    ct = cfp->iseq->catch_table;
+	    if (ct) for (i = 0; i < ct->size; i++) {
+		entry = &ct->entries[i];
+		if (entry->start < epc && entry->end >= epc) {
+
+		    if (entry->type == CATCH_TYPE_ENSURE) {
+			catch_iseqval = entry->iseq;
+			cont_pc = entry->cont;
+			cont_sp = entry->sp;
+			break;
+		    }
+		    else if (entry->type == CATCH_TYPE_RETRY) {
+			rb_control_frame_t *escape_cfp;
+			escape_cfp = GET_THROWOBJ_CATCH_POINT(err);
+			if (cfp == escape_cfp) {
+			    cfp->pc = cfp->iseq->iseq_encoded + entry->cont;
+			    th->errinfo = Qnil;
+			    goto vm_loop_start;
+			}
+		    }
+		}
+	    }
+	}
+	else if (state == TAG_BREAK && !escape_cfp) {
+	    type = CATCH_TYPE_BREAK;
+
+	  search_restart_point:
+	    ct = cfp->iseq->catch_table;
+	    if (ct) for (i = 0; i < ct->size; i++) {
+		entry = &ct->entries[i];
+
+		if (entry->start < epc && entry->end >= epc) {
+		    if (entry->type == CATCH_TYPE_ENSURE) {
+			catch_iseqval = entry->iseq;
+			cont_pc = entry->cont;
+			cont_sp = entry->sp;
+			break;
+		    }
+		    else if (entry->type == type) {
+			cfp->pc = cfp->iseq->iseq_encoded + entry->cont;
+			cfp->sp = vm_base_ptr(cfp) + entry->sp;
+
+			if (state != TAG_REDO) {
+#if OPT_STACK_CACHING
+			    initial = (GET_THROWOBJ_VAL(err));
+#else
+			    *th->cfp->sp++ = (GET_THROWOBJ_VAL(err));
+#endif
+			}
+			th->errinfo = Qnil;
+			th->state = 0;
+			goto vm_loop_start;
+		    }
+		}
+	    }
+	}
+	else if (state == TAG_REDO) {
+	    type = CATCH_TYPE_REDO;
+	    goto search_restart_point;
+	}
+	else if (state == TAG_NEXT) {
+	    type = CATCH_TYPE_NEXT;
+	    goto search_restart_point;
+	}
+	else {
+	    ct = cfp->iseq->catch_table;
+	    if (ct) for (i = 0; i < ct->size; i++) {
+		entry = &ct->entries[i];
+		if (entry->start < epc && entry->end >= epc) {
+
+		    if (entry->type == CATCH_TYPE_ENSURE) {
+			catch_iseqval = entry->iseq;
+			cont_pc = entry->cont;
+			cont_sp = entry->sp;
+			break;
+		    }
+		}
+	    }
+	}
+
+	if (catch_iseqval != 0) {
+	    /* found catch table */
+	    rb_iseq_t *catch_iseq;
+
+	    /* enter catch scope */
+	    GetISeqPtr(catch_iseqval, catch_iseq);
+	    cfp->sp = vm_base_ptr(cfp) + cont_sp;
+	    cfp->pc = cfp->iseq->iseq_encoded + cont_pc;
+
+	    /* push block frame */
+	    cfp->sp[0] = err;
+	    vm_push_frame(th, catch_iseq, VM_FRAME_MAGIC_RESCUE,
+			  cfp->self, cfp->klass,
+			  VM_ENVVAL_PREV_EP_PTR(cfp->ep),
+			  catch_iseq->iseq_encoded,
+			  cfp->sp + 1 /* push value */,
+			  catch_iseq->local_size - 1,
+			  cfp->me, catch_iseq->stack_max);
+
+	    state = 0;
+	    th->state = 0;
+	    th->errinfo = Qnil;
+	    goto vm_loop_start;
+	}
+	else {
+	    /* skip frame */
+	    hook_before_rewind(th, th->cfp);
+
+	    if (VM_FRAME_TYPE_FINISH_P(th->cfp)) {
+		vm_pop_frame(th);
+		th->errinfo = err;
+		TH_TMPPOP_TAG();
+		JUMP_TAG(state);
+	    }
+	    else {
+		th->cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(th->cfp);
+		goto exception_handler;
+	    }
+	}
+    }
+  finish_vme:
+    TH_POP_TAG();
+    return result;
+}
+
+/* misc */
+
+VALUE
+rb_iseq_eval(VALUE iseqval)
+{
+    rb_thread_t *th = GET_THREAD();
+    VALUE val;
+
+    vm_set_top_stack(th, iseqval);
+
+    val = vm_exec(th);
+    RB_GC_GUARD(iseqval); /* prohibit tail call optimization */
+    return val;
+}
+
+VALUE
+rb_iseq_eval_main(VALUE iseqval)
+{
+    rb_thread_t *th = GET_THREAD();
+    VALUE val;
+
+    vm_set_main_stack(th, iseqval);
+
+    val = vm_exec(th);
+    RB_GC_GUARD(iseqval); /* prohibit tail call optimization */
+    return val;
+}
+
+int
+rb_vm_control_frame_id_and_class(const rb_control_frame_t *cfp, ID *idp, VALUE *klassp)
+{
+    rb_iseq_t *iseq = cfp->iseq;
+    if (!iseq && cfp->me) {
+	if (idp) *idp = cfp->me->def->original_id;
+	if (klassp) *klassp = cfp->me->klass;
+	return 1;
+    }
+    while (iseq) {
+	if (RUBY_VM_IFUNC_P(iseq)) {
+	    if (idp) *idp = idIFUNC;
+	    if (klassp) *klassp = 0;
+	    return 1;
+	}
+	if (iseq->defined_method_id) {
+	    if (idp) *idp = iseq->defined_method_id;
+	    if (klassp) *klassp = iseq->klass;
+	    return 1;
+	}
+	if (iseq->local_iseq == iseq) {
+	    break;
+	}
+	iseq = iseq->parent_iseq;
+    }
+    return 0;
+}
+
+int
+rb_thread_method_id_and_class(rb_thread_t *th, ID *idp, VALUE *klassp)
+{
+    return rb_vm_control_frame_id_and_class(th->cfp, idp, klassp);
+}
+
+int
+rb_frame_method_id_and_class(ID *idp, VALUE *klassp)
+{
+    return rb_thread_method_id_and_class(GET_THREAD(), idp, klassp);
+}
+
+VALUE
+rb_thread_current_status(const rb_thread_t *th)
+{
+    const rb_control_frame_t *cfp = th->cfp;
+    VALUE str = Qnil;
+
+    if (cfp->iseq != 0) {
+	if (cfp->pc != 0) {
+	    rb_iseq_t *iseq = cfp->iseq;
+	    int line_no = rb_vm_get_sourceline(cfp);
+	    str = rb_sprintf("%"PRIsVALUE":%d:in `%"PRIsVALUE"'",
+			     iseq->location.path, line_no, iseq->location.label);
+	}
+    }
+    else if (cfp->me->def->original_id) {
+	str = rb_sprintf("`%"PRIsVALUE"#%"PRIsVALUE"' (cfunc)",
+			 rb_class_path(cfp->me->klass),
+			 rb_id2str(cfp->me->def->original_id));
+    }
+
+    return str;
+}
+
+VALUE
+rb_vm_call_cfunc(VALUE recv, VALUE (*func)(VALUE), VALUE arg,
+		 const rb_block_t *blockptr, VALUE filename)
+{
+    rb_thread_t *th = GET_THREAD();
+    const rb_control_frame_t *reg_cfp = th->cfp;
+    volatile VALUE iseqval = rb_iseq_new(0, filename, filename, Qnil, 0, ISEQ_TYPE_TOP);
+    VALUE val;
+
+    vm_push_frame(th, DATA_PTR(iseqval), VM_FRAME_MAGIC_TOP | VM_FRAME_FLAG_FINISH,
+		  recv, CLASS_OF(recv), VM_ENVVAL_BLOCK_PTR(blockptr), 0, reg_cfp->sp, 1, 0, 0);
+
+    val = (*func)(arg);
+
+    vm_pop_frame(th);
+    return val;
+}
+
+/* vm */
+
+void rb_vm_trace_mark_event_hooks(rb_hook_list_t *hooks);
+
+void
+rb_vm_mark(void *ptr)
+{
+    int i;
+
+    RUBY_MARK_ENTER("vm");
+    RUBY_GC_INFO("-------------------------------------------------\n");
+    if (ptr) {
+	rb_vm_t *vm = ptr;
+	rb_thread_t *th = 0;
+
+	list_for_each(&vm->living_threads, th, vmlt_node) {
+	    rb_gc_mark(th->self);
+	}
+	RUBY_MARK_UNLESS_NULL(vm->thgroup_default);
+	RUBY_MARK_UNLESS_NULL(vm->mark_object_ary);
+	RUBY_MARK_UNLESS_NULL(vm->load_path);
+	RUBY_MARK_UNLESS_NULL(vm->load_path_snapshot);
+	RUBY_MARK_UNLESS_NULL(vm->load_path_check_cache);
+	RUBY_MARK_UNLESS_NULL(vm->expanded_load_path);
+	RUBY_MARK_UNLESS_NULL(vm->loaded_features);
+	RUBY_MARK_UNLESS_NULL(vm->loaded_features_snapshot);
+	RUBY_MARK_UNLESS_NULL(vm->top_self);
+	RUBY_MARK_UNLESS_NULL(vm->coverages);
+	RUBY_MARK_UNLESS_NULL(vm->defined_module_hash);
+
+	if (vm->loading_table) {
+	    rb_mark_tbl(vm->loading_table);
+	}
+
+	rb_vm_trace_mark_event_hooks(&vm->event_hooks);
+
+	for (i = 0; i < RUBY_NSIG; i++) {
+	    if (vm->trap_list[i].cmd)
+		rb_gc_mark(vm->trap_list[i].cmd);
+	}
+    }
+
+    RUBY_MARK_LEAVE("vm");
+}
+
+void
+rb_vm_register_special_exception(enum ruby_special_exceptions sp, VALUE cls, const char *mesg)
+{
+    rb_vm_t *vm = GET_VM();
+    VALUE exc = rb_exc_new3(cls, rb_obj_freeze(rb_str_new2(mesg)));
+    OBJ_TAINT(exc);
+    OBJ_FREEZE(exc);
+    ((VALUE *)vm->special_exceptions)[sp] = exc;
+    rb_gc_register_mark_object(exc);
+}
+
+int
+rb_vm_add_root_module(ID id, VALUE module)
+{
+    rb_vm_t *vm = GET_VM();
+    if (vm->defined_module_hash) {
+	rb_hash_aset(vm->defined_module_hash, ID2SYM(id), module);
+    }
+    return TRUE;
+}
+
+int
+ruby_vm_destruct(rb_vm_t *vm)
+{
+    RUBY_FREE_ENTER("vm");
+
+    if (vm) {
+	rb_thread_t *th = vm->main_thread;
+#if defined(ENABLE_VM_OBJSPACE) && ENABLE_VM_OBJSPACE
+	struct rb_objspace *objspace = vm->objspace;
+#endif
+	vm->main_thread = 0;
+	if (th) {
+	    rb_fiber_reset_root_local_storage(th->self);
+	    thread_free(th);
+	}
+	rb_vm_living_threads_init(vm);
+	ruby_vm_run_at_exit_hooks(vm);
+	rb_vm_gvl_destroy(vm);
+#if defined(ENABLE_VM_OBJSPACE) && ENABLE_VM_OBJSPACE
+	if (objspace) {
+	    rb_objspace_free(objspace);
+	}
+#endif
+	/* after freeing objspace, you *can't* use ruby_xfree() */
+	ruby_mimfree(vm);
+	ruby_current_vm = 0;
+    }
+    RUBY_FREE_LEAVE("vm");
+    return 0;
+}
+
+static size_t
+vm_memsize(const void *ptr)
+{
+    if (ptr) {
+	const rb_vm_t *vmobj = ptr;
+	size_t size = sizeof(rb_vm_t);
+
+	size += vmobj->living_thread_num * sizeof(rb_thread_t);
+
+	if (vmobj->defined_strings) {
+	    size += DEFINED_EXPR * sizeof(VALUE);
+	}
+	return size;
+    }
+    else {
+	return 0;
+    }
+}
+
+static const rb_data_type_t vm_data_type = {
+    "VM",
+    {NULL, NULL, vm_memsize,},
+    0, 0, RUBY_TYPED_FREE_IMMEDIATELY
+};
+
+
+static VALUE
+vm_default_params(void)
+{
+    rb_vm_t *vm = GET_VM();
+    VALUE result = rb_hash_new();
+#define SET(name) rb_hash_aset(result, ID2SYM(rb_intern(#name)), SIZET2NUM(vm->default_params.name));
+    SET(thread_vm_stack_size);
+    SET(thread_machine_stack_size);
+    SET(fiber_vm_stack_size);
+    SET(fiber_machine_stack_size);
+#undef SET
+    rb_obj_freeze(result);
+    return result;
+}
+
+static size_t
+get_param(const char *name, size_t default_value, size_t min_value)
+{
+    const char *envval;
+    size_t result = default_value;
+    if ((envval = getenv(name)) != 0) {
+	long val = atol(envval);
+	if (val < (long)min_value) {
+	    val = (long)min_value;
+	}
+	result = (size_t)(((val -1 + RUBY_VM_SIZE_ALIGN) / RUBY_VM_SIZE_ALIGN) * RUBY_VM_SIZE_ALIGN);
+    }
+    if (0) fprintf(stderr, "%s: %"PRIdSIZE"\n", name, result); /* debug print */
+
+    return result;
+}
+
+static void
+check_machine_stack_size(size_t *sizep)
+{
+#ifdef PTHREAD_STACK_MIN
+    size_t size = *sizep;
+#endif
+
+#ifdef PTHREAD_STACK_MIN
+    if (size < PTHREAD_STACK_MIN) {
+	*sizep = PTHREAD_STACK_MIN * 2;
+    }
+#endif
+}
+
+static void
+vm_default_params_setup(rb_vm_t *vm)
+{
+    vm->default_params.thread_vm_stack_size =
+      get_param("RUBY_THREAD_VM_STACK_SIZE",
+		RUBY_VM_THREAD_VM_STACK_SIZE,
+		RUBY_VM_THREAD_VM_STACK_SIZE_MIN);
+
+    vm->default_params.thread_machine_stack_size =
+      get_param("RUBY_THREAD_MACHINE_STACK_SIZE",
+		RUBY_VM_THREAD_MACHINE_STACK_SIZE,
+		RUBY_VM_THREAD_MACHINE_STACK_SIZE_MIN);
+
+    vm->default_params.fiber_vm_stack_size =
+      get_param("RUBY_FIBER_VM_STACK_SIZE",
+		RUBY_VM_FIBER_VM_STACK_SIZE,
+		RUBY_VM_FIBER_VM_STACK_SIZE_MIN);
+
+    vm->default_params.fiber_machine_stack_size =
+      get_param("RUBY_FIBER_MACHINE_STACK_SIZE",
+		RUBY_VM_FIBER_MACHINE_STACK_SIZE,
+		RUBY_VM_FIBER_MACHINE_STACK_SIZE_MIN);
+
+    /* environment dependent check */
+    check_machine_stack_size(&vm->default_params.thread_machine_stack_size);
+    check_machine_stack_size(&vm->default_params.fiber_machine_stack_size);
+}
+
+static void
+vm_init2(rb_vm_t *vm)
+{
+    MEMZERO(vm, rb_vm_t, 1);
+    rb_vm_living_threads_init(vm);
+    vm->src_encoding_index = -1;
+    vm->at_exit.basic.flags = (T_ARRAY | RARRAY_EMBED_FLAG) & ~RARRAY_EMBED_LEN_MASK; /* len set 0 */
+    rb_obj_hide((VALUE)&vm->at_exit);
+
+    vm_default_params_setup(vm);
+}
+
+/* Thread */
+
+#define USE_THREAD_DATA_RECYCLE 1
+
+#if USE_THREAD_DATA_RECYCLE
+#define RECYCLE_MAX 64
+static VALUE *thread_recycle_stack_slot[RECYCLE_MAX];
+static int thread_recycle_stack_count = 0;
+
+static VALUE *
+thread_recycle_stack(size_t size)
+{
+    if (thread_recycle_stack_count) {
+	/* TODO: check stack size if stack sizes are variable */
+	return thread_recycle_stack_slot[--thread_recycle_stack_count];
+    }
+    else {
+	return ALLOC_N(VALUE, size);
+    }
+}
+
+#else
+#define thread_recycle_stack(size) ALLOC_N(VALUE, (size))
+#endif
+
+void
+rb_thread_recycle_stack_release(VALUE *stack)
+{
+#if USE_THREAD_DATA_RECYCLE
+    if (thread_recycle_stack_count < RECYCLE_MAX) {
+	thread_recycle_stack_slot[thread_recycle_stack_count++] = stack;
+	return;
+    }
+#endif
+    ruby_xfree(stack);
+}
+
+void rb_fiber_mark_self(rb_fiber_t *fib);
+
+void
+rb_thread_mark(void *ptr)
+{
+    rb_thread_t *th = NULL;
+    RUBY_MARK_ENTER("thread");
+    if (ptr) {
+	th = ptr;
+	if (th->stack) {
+	    VALUE *p = th->stack;
+	    VALUE *sp = th->cfp->sp;
+	    rb_control_frame_t *cfp = th->cfp;
+	    rb_control_frame_t *limit_cfp = (void *)(th->stack + th->stack_size);
+
+	    rb_gc_mark_values((long)(sp - p), p);
+
+	    while (cfp != limit_cfp) {
+		rb_iseq_t *iseq = cfp->iseq;
+		rb_gc_mark(cfp->proc);
+		rb_gc_mark(cfp->self);
+		rb_gc_mark(cfp->klass);
+		if (iseq) {
+		    rb_gc_mark(RUBY_VM_NORMAL_ISEQ_P(iseq) ? iseq->self : (VALUE)iseq);
+		}
+		if (cfp->me) {
+		    /* bitmap marking `me' does not seem worth the trouble:
+		     * [ruby-core:64340] [ruby-core:64341] */
+		    ((rb_method_entry_t *)cfp->me)->mark = 1;
+		    rb_mark_method_entry(cfp->me);
+		}
+		cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(cfp);
+	    }
+	}
+
+	/* mark ruby objects */
+	RUBY_MARK_UNLESS_NULL(th->first_proc);
+	if (th->first_proc) RUBY_MARK_UNLESS_NULL(th->first_args);
+
+	RUBY_MARK_UNLESS_NULL(th->thgroup);
+	RUBY_MARK_UNLESS_NULL(th->value);
+	RUBY_MARK_UNLESS_NULL(th->errinfo);
+	RUBY_MARK_UNLESS_NULL(th->pending_interrupt_queue);
+	RUBY_MARK_UNLESS_NULL(th->pending_interrupt_mask_stack);
+	RUBY_MARK_UNLESS_NULL(th->root_svar);
+	RUBY_MARK_UNLESS_NULL(th->top_self);
+	RUBY_MARK_UNLESS_NULL(th->top_wrapper);
+	rb_fiber_mark_self(th->fiber);
+	rb_fiber_mark_self(th->root_fiber);
+	RUBY_MARK_UNLESS_NULL(th->stat_insn_usage);
+	RUBY_MARK_UNLESS_NULL(th->last_status);
+
+	RUBY_MARK_UNLESS_NULL(th->locking_mutex);
+
+	rb_mark_tbl(th->local_storage);
+	RUBY_MARK_UNLESS_NULL(th->local_storage_recursive_hash);
+	RUBY_MARK_UNLESS_NULL(th->local_storage_recursive_hash_for_trace);
+
+	if (GET_THREAD() != th && th->machine.stack_start && th->machine.stack_end) {
+	    rb_gc_mark_machine_stack(th);
+	    rb_gc_mark_locations((VALUE *)&th->machine.regs,
+				 (VALUE *)(&th->machine.regs) +
+				 sizeof(th->machine.regs) / sizeof(VALUE));
+	}
+
+	rb_vm_trace_mark_event_hooks(&th->event_hooks);
+    }
+
+    RUBY_MARK_LEAVE("thread");
+}
+
+static void
+thread_free(void *ptr)
+{
+    rb_thread_t *th;
+    RUBY_FREE_ENTER("thread");
+
+    if (ptr) {
+	th = ptr;
+
+	if (!th->root_fiber) {
+	    RUBY_FREE_UNLESS_NULL(th->stack);
+	}
+
+	if (th->locking_mutex != Qfalse) {
+	    rb_bug("thread_free: locking_mutex must be NULL (%p:%p)", (void *)th, (void *)th->locking_mutex);
+	}
+	if (th->keeping_mutexes != NULL) {
+	    rb_bug("thread_free: keeping_mutexes must be NULL (%p:%p)", (void *)th, (void *)th->keeping_mutexes);
+	}
+
+	if (th->local_storage) {
+	    st_free_table(th->local_storage);
+	}
+
+	if (th->vm && th->vm->main_thread == th) {
+	    RUBY_GC_INFO("main thread\n");
+	}
+	else {
+#ifdef USE_SIGALTSTACK
+	    if (th->altstack) {
+		free(th->altstack);
+	    }
+#endif
+	    ruby_xfree(ptr);
+	}
+        if (ruby_current_thread == th)
+            ruby_current_thread = NULL;
+    }
+    RUBY_FREE_LEAVE("thread");
+}
+
+static size_t
+thread_memsize(const void *ptr)
+{
+    if (ptr) {
+	const rb_thread_t *th = ptr;
+	size_t size = sizeof(rb_thread_t);
+
+	if (!th->root_fiber) {
+	    size += th->stack_size * sizeof(VALUE);
+	}
+	if (th->local_storage) {
+	    size += st_memsize(th->local_storage);
+	}
+	return size;
+    }
+    else {
+	return 0;
+    }
+}
+
+#define thread_data_type ruby_threadptr_data_type
+const rb_data_type_t ruby_threadptr_data_type = {
+    "VM/thread",
+    {
+	rb_thread_mark,
+	thread_free,
+	thread_memsize,
+    },
+    0, 0, RUBY_TYPED_FREE_IMMEDIATELY
+};
+
+VALUE
+rb_obj_is_thread(VALUE obj)
+{
+    if (rb_typeddata_is_kind_of(obj, &thread_data_type)) {
+	return Qtrue;
+    }
+    else {
+	return Qfalse;
+    }
+}
+
+static VALUE
+thread_alloc(VALUE klass)
+{
+    VALUE obj;
+    rb_thread_t *th;
+    obj = TypedData_Make_Struct(klass, rb_thread_t, &thread_data_type, th);
+
+    return obj;
+}
+
+static void
+th_init(rb_thread_t *th, VALUE self)
+{
+    th->self = self;
+
+    /* allocate thread stack */
+#ifdef USE_SIGALTSTACK
+    /* altstack of main thread is reallocated in another place */
+    th->altstack = malloc(rb_sigaltstack_size());
+#endif
+    /* th->stack_size is word number.
+     * th->vm->default_params.thread_vm_stack_size is byte size.
+     */
+    th->stack_size = th->vm->default_params.thread_vm_stack_size / sizeof(VALUE);
+    th->stack = thread_recycle_stack(th->stack_size);
+
+    th->cfp = (void *)(th->stack + th->stack_size);
+
+    vm_push_frame(th, 0 /* dummy iseq */, VM_FRAME_MAGIC_TOP | VM_FRAME_FLAG_FINISH,
+		  Qnil /* dummy self */, Qnil /* dummy klass */, VM_ENVVAL_BLOCK_PTR(0), 0 /* dummy pc */, th->stack, 1, 0, 0);
+
+    th->status = THREAD_RUNNABLE;
+    th->errinfo = Qnil;
+    th->last_status = Qnil;
+    th->waiting_fd = -1;
+    th->root_svar = Qnil;
+    th->local_storage_recursive_hash = Qnil;
+    th->local_storage_recursive_hash_for_trace = Qnil;
+#ifdef NON_SCALAR_THREAD_ID
+    th->thread_id_string[0] = '\0';
+#endif
+
+#if OPT_CALL_THREADED_CODE
+    th->retval = Qundef;
+#endif
+}
+
+static VALUE
+ruby_thread_init(VALUE self)
+{
+    rb_thread_t *th;
+    rb_vm_t *vm = GET_THREAD()->vm;
+    GetThreadPtr(self, th);
+
+    th->vm = vm;
+    th_init(th, self);
+    rb_ivar_set(self, rb_intern("locals"), rb_hash_new());
+
+    th->top_wrapper = 0;
+    th->top_self = rb_vm_top_self();
+    th->root_svar = Qnil;
+    return self;
+}
+
+VALUE
+rb_thread_alloc(VALUE klass)
+{
+    VALUE self = thread_alloc(klass);
+    ruby_thread_init(self);
+    return self;
+}
+
+static void
+vm_define_method(rb_thread_t *th, VALUE obj, ID id, VALUE iseqval,
+		 rb_num_t is_singleton, NODE *cref)
+{
+    VALUE klass = cref->nd_clss;
+    int noex = (int)cref->nd_visi;
+    rb_iseq_t *miseq;
+    GetISeqPtr(iseqval, miseq);
+
+    if (miseq->klass) {
+	RB_GC_GUARD(iseqval) = rb_iseq_clone(iseqval, 0);
+	GetISeqPtr(iseqval, miseq);
+    }
+
+    if (NIL_P(klass)) {
+	rb_raise(rb_eTypeError, "no class/module to add method");
+    }
+
+    if (is_singleton) {
+	klass = rb_singleton_class(obj); /* class and frozen checked in this API */
+	noex = NOEX_PUBLIC;
+    }
+
+    /* dup */
+    COPY_CREF(miseq->cref_stack, cref);
+    miseq->cref_stack->nd_visi = NOEX_PUBLIC;
+    RB_OBJ_WRITE(miseq->self, &miseq->klass, klass);
+    miseq->defined_method_id = id;
+    rb_add_method(klass, id, VM_METHOD_TYPE_ISEQ, miseq, noex);
+
+    if (!is_singleton && noex == NOEX_MODFUNC) {
+	klass = rb_singleton_class(klass);
+	rb_add_method(klass, id, VM_METHOD_TYPE_ISEQ, miseq, NOEX_PUBLIC);
+    }
+}
+
+#define REWIND_CFP(expr) do { \
+    rb_thread_t *th__ = GET_THREAD(); \
+    VALUE *const curr_sp = (th__->cfp++)->sp; \
+    VALUE *const saved_sp = th__->cfp->sp; \
+    th__->cfp->sp = curr_sp; \
+    expr; \
+    (th__->cfp--)->sp = saved_sp; \
+} while (0)
+
+static VALUE
+m_core_define_method(VALUE self, VALUE cbase, VALUE sym, VALUE iseqval)
+{
+    REWIND_CFP({
+	vm_define_method(GET_THREAD(), cbase, SYM2ID(sym), iseqval, 0, rb_vm_cref());
+    });
+    return sym;
+}
+
+static VALUE
+m_core_define_singleton_method(VALUE self, VALUE cbase, VALUE sym, VALUE iseqval)
+{
+    REWIND_CFP({
+	vm_define_method(GET_THREAD(), cbase, SYM2ID(sym), iseqval, 1, rb_vm_cref());
+    });
+    return sym;
+}
+
+static VALUE
+m_core_set_method_alias(VALUE self, VALUE cbase, VALUE sym1, VALUE sym2)
+{
+    REWIND_CFP({
+	rb_alias(cbase, SYM2ID(sym1), SYM2ID(sym2));
+    });
+    return Qnil;
+}
+
+static VALUE
+m_core_set_variable_alias(VALUE self, VALUE sym1, VALUE sym2)
+{
+    REWIND_CFP({
+	rb_alias_variable(SYM2ID(sym1), SYM2ID(sym2));
+    });
+    return Qnil;
+}
+
+static VALUE
+m_core_undef_method(VALUE self, VALUE cbase, VALUE sym)
+{
+    REWIND_CFP({
+	rb_undef(cbase, SYM2ID(sym));
+	rb_clear_method_cache_by_class(self);
+    });
+    return Qnil;
+}
+
+static VALUE
+m_core_set_postexe(VALUE self)
+{
+    rb_set_end_proc(rb_call_end_proc, rb_block_proc());
+    return Qnil;
+}
+
+static VALUE core_hash_merge_ary(VALUE hash, VALUE ary);
+static VALUE core_hash_from_ary(VALUE ary);
+static VALUE core_hash_merge_kwd(int argc, VALUE *argv);
+
+static VALUE
+core_hash_merge(VALUE hash, long argc, const VALUE *argv)
+{
+    long i;
+
+    assert(argc % 2 == 0);
+    for (i=0; i<argc; i+=2) {
+	rb_hash_aset(hash, argv[i], argv[i+1]);
+    }
+    return hash;
+}
+
+static VALUE
+m_core_hash_from_ary(VALUE self, VALUE ary)
+{
+    VALUE hash;
+    REWIND_CFP(hash = core_hash_from_ary(ary));
+    return hash;
+}
+
+static VALUE
+core_hash_from_ary(VALUE ary)
+{
+    VALUE hash = rb_hash_new();
+
+    if (RUBY_DTRACE_HASH_CREATE_ENABLED()) {
+	RUBY_DTRACE_HASH_CREATE(RARRAY_LEN(ary), rb_sourcefile(), rb_sourceline());
+    }
+
+    return core_hash_merge_ary(hash, ary);
+}
+
+static VALUE
+m_core_hash_merge_ary(VALUE self, VALUE hash, VALUE ary)
+{
+    REWIND_CFP(core_hash_merge_ary(hash, ary));
+    return hash;
+}
+
+static VALUE
+core_hash_merge_ary(VALUE hash, VALUE ary)
+{
+    core_hash_merge(hash, RARRAY_LEN(ary), RARRAY_CONST_PTR(ary));
+    return hash;
+}
+
+static VALUE
+m_core_hash_merge_ptr(int argc, VALUE *argv, VALUE recv)
+{
+    VALUE hash = argv[0];
+
+    REWIND_CFP(core_hash_merge(hash, argc-1, argv+1));
+
+    return hash;
+}
+
+static int
+kwmerge_i(VALUE key, VALUE value, VALUE hash)
+{
+    if (!SYMBOL_P(key)) Check_Type(key, T_SYMBOL);
+    rb_hash_aset(hash, key, value);
+    return ST_CONTINUE;
+}
+
+static int
+kwcheck_i(VALUE key, VALUE value, VALUE hash)
+{
+    if (!SYMBOL_P(key)) Check_Type(key, T_SYMBOL);
+    return ST_CONTINUE;
+}
+
+static VALUE
+m_core_hash_merge_kwd(int argc, VALUE *argv, VALUE recv)
+{
+    VALUE hash;
+    REWIND_CFP(hash = core_hash_merge_kwd(argc, argv));
+    return hash;
+}
+
+static VALUE
+core_hash_merge_kwd(int argc, VALUE *argv)
+{
+    VALUE hash, kw;
+    rb_check_arity(argc, 1, 2);
+    hash = argv[0];
+    kw = argv[argc-1];
+    kw = rb_convert_type(kw, T_HASH, "Hash", "to_hash");
+    if (argc < 2) hash = kw;
+    rb_hash_foreach(kw, argc < 2 ? kwcheck_i : kwmerge_i, hash);
+    return hash;
+}
+
+extern VALUE *rb_gc_stack_start;
+extern size_t rb_gc_stack_maxsize;
+#ifdef __ia64
+extern VALUE *rb_gc_register_stack_start;
+#endif
+
+/* debug functions */
+
+/* :nodoc: */
+static VALUE
+sdr(void)
+{
+    rb_vm_bugreport(NULL);
+    return Qnil;
+}
+
+/* :nodoc: */
+static VALUE
+nsdr(void)
+{
+    VALUE ary = rb_ary_new();
+#if HAVE_BACKTRACE
+#include <execinfo.h>
+#define MAX_NATIVE_TRACE 1024
+    static void *trace[MAX_NATIVE_TRACE];
+    int n = (int)backtrace(trace, MAX_NATIVE_TRACE);
+    char **syms = backtrace_symbols(trace, n);
+    int i;
+
+    if (syms == 0) {
+	rb_memerror();
+    }
+
+    for (i=0; i<n; i++) {
+	rb_ary_push(ary, rb_str_new2(syms[i]));
+    }
+    free(syms); /* OK */
+#endif
+    return ary;
+}
+
+#if VM_COLLECT_USAGE_DETAILS
+static VALUE usage_analysis_insn_stop(VALUE self);
+static VALUE usage_analysis_operand_stop(VALUE self);
+static VALUE usage_analysis_register_stop(VALUE self);
+#endif
+
+void
+Init_VM(void)
+{
+    VALUE opts;
+    VALUE klass;
+    VALUE fcore;
+
+    /* ::RubyVM */
+    rb_cRubyVM = rb_define_class("RubyVM", rb_cObject);
+    rb_undef_alloc_func(rb_cRubyVM);
+    rb_undef_method(CLASS_OF(rb_cRubyVM), "new");
+    rb_define_singleton_method(rb_cRubyVM, "stat", vm_stat, -1);
+
+    /* FrozenCore (hidden) */
+    fcore = rb_class_new(rb_cBasicObject);
+    RBASIC(fcore)->flags = T_ICLASS;
+    klass = rb_singleton_class(fcore);
+    rb_define_method_id(klass, id_core_set_method_alias, m_core_set_method_alias, 3);
+    rb_define_method_id(klass, id_core_set_variable_alias, m_core_set_variable_alias, 2);
+    rb_define_method_id(klass, id_core_undef_method, m_core_undef_method, 2);
+    rb_define_method_id(klass, id_core_define_method, m_core_define_method, 3);
+    rb_define_method_id(klass, id_core_define_singleton_method, m_core_define_singleton_method, 3);
+    rb_define_method_id(klass, id_core_set_postexe, m_core_set_postexe, 0);
+    rb_define_method_id(klass, id_core_hash_from_ary, m_core_hash_from_ary, 1);
+    rb_define_method_id(klass, id_core_hash_merge_ary, m_core_hash_merge_ary, 2);
+    rb_define_method_id(klass, id_core_hash_merge_ptr, m_core_hash_merge_ptr, -1);
+    rb_define_method_id(klass, id_core_hash_merge_kwd, m_core_hash_merge_kwd, -1);
+    rb_define_method_id(klass, idProc, rb_block_proc, 0);
+    rb_define_method_id(klass, idLambda, rb_block_lambda, 0);
+    rb_obj_freeze(fcore);
+    RBASIC_CLEAR_CLASS(klass);
+    RCLASS_SET_SUPER(klass, 0);
+    rb_obj_freeze(klass);
+    rb_gc_register_mark_object(fcore);
+    rb_mRubyVMFrozenCore = fcore;
+
+    /* ::RubyVM::Env */
+    rb_cEnv = rb_define_class_under(rb_cRubyVM, "Env", rb_cObject);
+    rb_undef_alloc_func(rb_cEnv);
+    rb_undef_method(CLASS_OF(rb_cEnv), "new");
+
+    /*
+     * Document-class: Thread
+     *
+     *	Threads are the Ruby implementation for a concurrent programming model.
+     *
+     *	Programs that require multiple threads of execution are a perfect
+     *	candidate for Ruby's Thread class.
+     *
+     *	For example, we can create a new thread separate from the main thread's
+     *	execution using ::new.
+     *
+     *	    thr = Thread.new { puts "Whats the big deal" }
+     *
+     *	Then we are able to pause the execution of the main thread and allow
+     *	our new thread to finish, using #join:
+     *
+     *	    thr.join #=> "Whats the big deal"
+     *
+     *	If we don't call +thr.join+ before the main thread terminates, then all
+     *	other threads including +thr+ will be killed.
+     *
+     *	Alternatively, you can use an array for handling multiple threads at
+     *	once, like in the following example:
+     *
+     *	    threads = []
+     *	    threads << Thread.new { puts "Whats the big deal" }
+     *	    threads << Thread.new { 3.times { puts "Threads are fun!" } }
+     *
+     *	After creating a few threads we wait for them all to finish
+     *	consecutively.
+     *
+     *	    threads.each { |thr| thr.join }
+     *
+     *	=== Thread initialization
+     *
+     *	In order to create new threads, Ruby provides ::new, ::start, and
+     *	::fork. A block must be provided with each of these methods, otherwise
+     *	a ThreadError will be raised.
+     *
+     *	When subclassing the Thread class, the +initialize+ method of your
+     *	subclass will be ignored by ::start and ::fork. Otherwise, be sure to
+     *	call super in your +initialize+ method.
+     *
+     * 	=== Thread termination
+     *
+     * 	For terminating threads, Ruby provides a variety of ways to do this.
+     *
+     *	The class method ::kill, is meant to exit a given thread:
+     *
+     *	    thr = Thread.new { ... }
+     *	    Thread.kill(thr) # sends exit() to thr
+     *
+     *	Alternatively, you can use the instance method #exit, or any of its
+     *	aliases #kill or #terminate.
+     *
+     *	    thr.exit
+     *
+     * 	=== Thread status
+     *
+     * 	Ruby provides a few instance methods for querying the state of a given
+     * 	thread. To get a string with the current thread's state use #status
+     *
+     *	    thr = Thread.new { sleep }
+     *	    thr.status # => "sleep"
+     *	    thr.exit
+     *	    thr.status # => false
+     *
+     *	You can also use #alive? to tell if the thread is running or sleeping,
+     *	and #stop? if the thread is dead or sleeping.
+     *
+     * 	=== Thread variables and scope
+     *
+     * 	Since threads are created with blocks, the same rules apply to other
+     * 	Ruby blocks for variable scope. Any local variables created within this
+     * 	block are accessible to only this thread.
+     *
+     * 	==== Fiber-local vs. Thread-local
+     *
+     *	Each fiber has its own bucket for Thread#[] storage. When you set a
+     *	new fiber-local it is only accessible within this Fiber. To illustrate:
+     *
+     *	    Thread.new {
+     *	      Thread.current[:foo] = "bar"
+     *	      Fiber.new {
+     *	        p Thread.current[:foo] # => nil
+     *	      }.resume
+     *	    }.join
+     *
+     * 	This example uses #[] for getting and #[]= for setting fiber-locals,
+     * 	you can also use #keys to list the fiber-locals for a given
+     * 	thread and #key? to check if a fiber-local exists.
+     *
+     *	When it comes to thread-locals, they are accessible within the entire
+     *	scope of the thread. Given the following example:
+     *
+     *	    Thread.new{
+     *	      Thread.current.thread_variable_set(:foo, 1)
+     *	      p Thread.current.thread_variable_get(:foo) # => 1
+     *	      Fiber.new{
+     *		Thread.current.thread_variable_set(:foo, 2)
+     *		p Thread.current.thread_variable_get(:foo) # => 2
+     *	      }.resume
+     *	      p Thread.current.thread_variable_get(:foo)   # => 2
+     *	    }.join
+     *
+     *  You can see that the thread-local +:foo+ carried over into the fiber
+     *  and was changed to +2+ by the end of the thread.
+     *
+     *  This example makes use of #thread_variable_set to create new
+     *  thread-locals, and #thread_variable_get to reference them.
+     *
+     *  There is also #thread_variables to list all thread-locals, and
+     *  #thread_variable? to check if a given thread-local exists.
+     *
+     * 	=== Exception handling
+     *
+     *	Any thread can raise an exception using the #raise instance method,
+     *	which operates similarly to Kernel#raise.
+     *
+     *	However, it's important to note that an exception that occurs in any
+     *	thread except the main thread depends on #abort_on_exception. This
+     *	option is +false+ by default, meaning that any unhandled exception will
+     *	cause the thread to terminate silently when waited on by either #join
+     *	or #value. You can change this default by either #abort_on_exception=
+     *	+true+ or setting $DEBUG to +true+.
+     *
+     *	With the addition of the class method ::handle_interrupt, you can now
+     *	handle exceptions asynchronously with threads.
+     *
+     * 	=== Scheduling
+     *
+     * 	Ruby provides a few ways to support scheduling threads in your program.
+     *
+     * 	The first way is by using the class method ::stop, to put the current
+     * 	running thread to sleep and schedule the execution of another thread.
+     *
+     * 	Once a thread is asleep, you can use the instance method #wakeup to
+     * 	mark your thread as eligible for scheduling.
+     *
+     * 	You can also try ::pass, which attempts to pass execution to another
+     * 	thread but is dependent on the OS whether a running thread will switch
+     * 	or not. The same goes for #priority, which lets you hint to the thread
+     * 	scheduler which threads you want to take precedence when passing
+     * 	execution. This method is also dependent on the OS and may be ignored
+     * 	on some platforms.
+     *
+     */
+    rb_cThread = rb_define_class("Thread", rb_cObject);
+    rb_undef_alloc_func(rb_cThread);
+
+#if VM_COLLECT_USAGE_DETAILS
+    /* ::RubyVM::USAGE_ANALYSIS_* */
+#define define_usage_analysis_hash(name) /* shut up rdoc -C */ \
+    rb_define_const(rb_cRubyVM, "USAGE_ANALYSIS_"#name, rb_hash_new())
+    define_usage_analysis_hash("INSN");
+    define_usage_analysis_hash("REGS");
+    define_usage_analysis_hash("INSN_BIGRAM");
+
+    rb_define_singleton_method(rb_cRubyVM, "USAGE_ANALYSIS_INSN_STOP", usage_analysis_insn_stop, 0);
+    rb_define_singleton_method(rb_cRubyVM, "USAGE_ANALYSIS_OPERAND_STOP", usage_analysis_operand_stop, 0);
+    rb_define_singleton_method(rb_cRubyVM, "USAGE_ANALYSIS_REGISTER_STOP", usage_analysis_register_stop, 0);
+#endif
+
+    /* ::RubyVM::OPTS, which shows vm build options */
+    rb_define_const(rb_cRubyVM, "OPTS", opts = rb_ary_new());
+
+#if   OPT_DIRECT_THREADED_CODE
+    rb_ary_push(opts, rb_str_new2("direct threaded code"));
+#elif OPT_TOKEN_THREADED_CODE
+    rb_ary_push(opts, rb_str_new2("token threaded code"));
+#elif OPT_CALL_THREADED_CODE
+    rb_ary_push(opts, rb_str_new2("call threaded code"));
+#endif
+
+#if OPT_STACK_CACHING
+    rb_ary_push(opts, rb_str_new2("stack caching"));
+#endif
+#if OPT_OPERANDS_UNIFICATION
+    rb_ary_push(opts, rb_str_new2("operands unification"));
+#endif
+#if OPT_INSTRUCTIONS_UNIFICATION
+    rb_ary_push(opts, rb_str_new2("instructions unification"));
+#endif
+#if OPT_INLINE_METHOD_CACHE
+    rb_ary_push(opts, rb_str_new2("inline method cache"));
+#endif
+#if OPT_BLOCKINLINING
+    rb_ary_push(opts, rb_str_new2("block inlining"));
+#endif
+
+    /* ::RubyVM::INSTRUCTION_NAMES */
+    rb_define_const(rb_cRubyVM, "INSTRUCTION_NAMES", rb_insns_name_array());
+
+    /* ::RubyVM::DEFAULT_PARAMS
+     * This constant variable shows VM's default parameters.
+     * Note that changing these values does not affect VM execution.
+     * Specification is not stable and you should not depend on this value.
+     * Of course, this constant is MRI specific.
+     */
+    rb_define_const(rb_cRubyVM, "DEFAULT_PARAMS", vm_default_params());
+
+    /* debug functions ::RubyVM::SDR(), ::RubyVM::NSDR() */
+#if VMDEBUG
+    rb_define_singleton_method(rb_cRubyVM, "SDR", sdr, 0);
+    rb_define_singleton_method(rb_cRubyVM, "NSDR", nsdr, 0);
+#else
+    (void)sdr;
+    (void)nsdr;
+#endif
+
+    /* VM bootstrap: phase 2 */
+    {
+	rb_vm_t *vm = ruby_current_vm;
+	rb_thread_t *th = GET_THREAD();
+	VALUE filename = rb_str_new2("<main>");
+	volatile VALUE iseqval = rb_iseq_new(0, filename, filename, Qnil, 0, ISEQ_TYPE_TOP);
+        volatile VALUE th_self;
+	rb_iseq_t *iseq;
+
+	/* create vm object */
+	vm->self = TypedData_Wrap_Struct(rb_cRubyVM, &vm_data_type, vm);
+
+	/* create main thread */
+	th_self = th->self = TypedData_Wrap_Struct(rb_cThread, &thread_data_type, th);
+	rb_iv_set(th_self, "locals", rb_hash_new());
+	vm->main_thread = th;
+	vm->running_thread = th;
+	th->vm = vm;
+	th->top_wrapper = 0;
+	th->top_self = rb_vm_top_self();
+	rb_thread_set_current(th);
+
+	rb_vm_living_threads_insert(vm, th);
+
+	rb_gc_register_mark_object(iseqval);
+	GetISeqPtr(iseqval, iseq);
+	th->cfp->iseq = iseq;
+	th->cfp->pc = iseq->iseq_encoded;
+	th->cfp->self = th->top_self;
+	th->cfp->klass = Qnil;
+
+	/*
+	 * The Binding of the top level scope
+	 */
+	rb_define_global_const("TOPLEVEL_BINDING", rb_binding_new());
+    }
+    vm_init_redefined_flag();
+
+    /* vm_backtrace.c */
+    Init_vm_backtrace();
+    VM_PROFILE_ATEXIT();
+}
+
+void
+rb_vm_set_progname(VALUE filename)
+{
+    rb_thread_t *th = GET_VM()->main_thread;
+    rb_control_frame_t *cfp = (void *)(th->stack + th->stack_size);
+    --cfp;
+    RB_OBJ_WRITE(cfp->iseq->self, &cfp->iseq->location.path, filename);
+}
+
+#if defined(ENABLE_VM_OBJSPACE) && ENABLE_VM_OBJSPACE
+struct rb_objspace *rb_objspace_alloc(void);
+#endif
+
+void
+Init_BareVM(void)
+{
+    /* VM bootstrap: phase 1 */
+    rb_vm_t * vm = ruby_mimmalloc(sizeof(*vm));
+    rb_thread_t * th = ruby_mimmalloc(sizeof(*th));
+    if (!vm || !th) {
+	fprintf(stderr, "[FATAL] failed to allocate memory\n");
+	exit(EXIT_FAILURE);
+    }
+    MEMZERO(th, rb_thread_t, 1);
+    rb_thread_set_current_raw(th);
+
+    vm_init2(vm);
+#if defined(ENABLE_VM_OBJSPACE) && ENABLE_VM_OBJSPACE
+    vm->objspace = rb_objspace_alloc();
+#endif
+    ruby_current_vm = vm;
+
+    Init_native_thread();
+    th->vm = vm;
+    th_init(th, 0);
+    ruby_thread_init_stack(th);
+}
+
+void
+Init_vm_objects(void)
+{
+    rb_vm_t *vm = GET_VM();
+
+    vm->defined_module_hash = rb_hash_new();
+
+    /* initialize mark object array, hash */
+    vm->mark_object_ary = rb_ary_tmp_new(128);
+}
+
+/* top self */
+
+static VALUE
+main_to_s(VALUE obj)
+{
+    return rb_str_new2("main");
+}
+
+VALUE
+rb_vm_top_self(void)
+{
+    return GET_VM()->top_self;
+}
+
+void
+Init_top_self(void)
+{
+    rb_vm_t *vm = GET_VM();
+
+    vm->top_self = rb_obj_alloc(rb_cObject);
+    rb_define_singleton_method(rb_vm_top_self(), "to_s", main_to_s, 0);
+    rb_define_alias(rb_singleton_class(rb_vm_top_self()), "inspect", "to_s");
+}
+
+VALUE *
+ruby_vm_verbose_ptr(rb_vm_t *vm)
+{
+    return &vm->verbose;
+}
+
+VALUE *
+ruby_vm_debug_ptr(rb_vm_t *vm)
+{
+    return &vm->debug;
+}
+
+VALUE *
+rb_ruby_verbose_ptr(void)
+{
+    return ruby_vm_verbose_ptr(GET_VM());
+}
+
+VALUE *
+rb_ruby_debug_ptr(void)
+{
+    return ruby_vm_debug_ptr(GET_VM());
+}
+
+/* iseq.c */
+VALUE rb_insn_operand_intern(rb_iseq_t *iseq,
+			     VALUE insn, int op_no, VALUE op,
+			     int len, size_t pos, VALUE *pnop, VALUE child);
+
+#if VM_COLLECT_USAGE_DETAILS
+
+#define HASH_ASET(h, k, v) rb_hash_aset((h), (st_data_t)(k), (st_data_t)(v))
+
+/* uh = {
+ *   insn(Fixnum) => ihash(Hash)
+ * }
+ * ihash = {
+ *   -1(Fixnum) => count,      # insn usage
+ *    0(Fixnum) => ophash,     # operand usage
+ * }
+ * ophash = {
+ *   val(interned string) => count(Fixnum)
+ * }
+ */
+static void
+vm_analysis_insn(int insn)
+{
+    ID usage_hash;
+    ID bigram_hash;
+    static int prev_insn = -1;
+
+    VALUE uh;
+    VALUE ihash;
+    VALUE cv;
+
+    CONST_ID(usage_hash, "USAGE_ANALYSIS_INSN");
+    CONST_ID(bigram_hash, "USAGE_ANALYSIS_INSN_BIGRAM");
+    uh = rb_const_get(rb_cRubyVM, usage_hash);
+    if ((ihash = rb_hash_aref(uh, INT2FIX(insn))) == Qnil) {
+	ihash = rb_hash_new();
+	HASH_ASET(uh, INT2FIX(insn), ihash);
+    }
+    if ((cv = rb_hash_aref(ihash, INT2FIX(-1))) == Qnil) {
+	cv = INT2FIX(0);
+    }
+    HASH_ASET(ihash, INT2FIX(-1), INT2FIX(FIX2INT(cv) + 1));
+
+    /* calc bigram */
+    if (prev_insn != -1) {
+	VALUE bi;
+	VALUE ary[2];
+	VALUE cv;
+
+	ary[0] = INT2FIX(prev_insn);
+	ary[1] = INT2FIX(insn);
+	bi = rb_ary_new4(2, &ary[0]);
+
+	uh = rb_const_get(rb_cRubyVM, bigram_hash);
+	if ((cv = rb_hash_aref(uh, bi)) == Qnil) {
+	    cv = INT2FIX(0);
+	}
+	HASH_ASET(uh, bi, INT2FIX(FIX2INT(cv) + 1));
+    }
+    prev_insn = insn;
+}
+
+static void
+vm_analysis_operand(int insn, int n, VALUE op)
+{
+    ID usage_hash;
+
+    VALUE uh;
+    VALUE ihash;
+    VALUE ophash;
+    VALUE valstr;
+    VALUE cv;
+
+    CONST_ID(usage_hash, "USAGE_ANALYSIS_INSN");
+
+    uh = rb_const_get(rb_cRubyVM, usage_hash);
+    if ((ihash = rb_hash_aref(uh, INT2FIX(insn))) == Qnil) {
+	ihash = rb_hash_new();
+	HASH_ASET(uh, INT2FIX(insn), ihash);
+    }
+    if ((ophash = rb_hash_aref(ihash, INT2FIX(n))) == Qnil) {
+	ophash = rb_hash_new();
+	HASH_ASET(ihash, INT2FIX(n), ophash);
+    }
+    /* intern */
+    valstr = rb_insn_operand_intern(GET_THREAD()->cfp->iseq, insn, n, op, 0, 0, 0, 0);
+
+    /* set count */
+    if ((cv = rb_hash_aref(ophash, valstr)) == Qnil) {
+	cv = INT2FIX(0);
+    }
+    HASH_ASET(ophash, valstr, INT2FIX(FIX2INT(cv) + 1));
+}
+
+static void
+vm_analysis_register(int reg, int isset)
+{
+    ID usage_hash;
+    VALUE uh;
+    VALUE valstr;
+    static const char regstrs[][5] = {
+	"pc",			/* 0 */
+	"sp",			/* 1 */
+	"ep",                   /* 2 */
+	"cfp",			/* 3 */
+	"self",			/* 4 */
+	"iseq",			/* 5 */
+    };
+    static const char getsetstr[][4] = {
+	"get",
+	"set",
+    };
+    static VALUE syms[sizeof(regstrs) / sizeof(regstrs[0])][2];
+
+    VALUE cv;
+
+    CONST_ID(usage_hash, "USAGE_ANALYSIS_REGS");
+    if (syms[0] == 0) {
+	char buff[0x10];
+	int i;
+
+	for (i = 0; i < (int)(sizeof(regstrs) / sizeof(regstrs[0])); i++) {
+	    int j;
+	    for (j = 0; j < 2; j++) {
+		snprintf(buff, 0x10, "%d %s %-4s", i, getsetstr[j], regstrs[i]);
+		syms[i][j] = ID2SYM(rb_intern(buff));
+	    }
+	}
+    }
+    valstr = syms[reg][isset];
+
+    uh = rb_const_get(rb_cRubyVM, usage_hash);
+    if ((cv = rb_hash_aref(uh, valstr)) == Qnil) {
+	cv = INT2FIX(0);
+    }
+    HASH_ASET(uh, valstr, INT2FIX(FIX2INT(cv) + 1));
+}
+
+#undef HASH_ASET
+
+void (*ruby_vm_collect_usage_func_insn)(int insn) = vm_analysis_insn;
+void (*ruby_vm_collect_usage_func_operand)(int insn, int n, VALUE op) = vm_analysis_operand;
+void (*ruby_vm_collect_usage_func_register)(int reg, int isset) = vm_analysis_register;
+
+/* :nodoc: */
+static VALUE
+usage_analysis_insn_stop(VALUE self)
+{
+    ruby_vm_collect_usage_func_insn = 0;
+    return Qnil;
+}
+
+/* :nodoc: */
+static VALUE
+usage_analysis_operand_stop(VALUE self)
+{
+    ruby_vm_collect_usage_func_operand = 0;
+    return Qnil;
+}
+
+/* :nodoc: */
+static VALUE
+usage_analysis_register_stop(VALUE self)
+{
+    ruby_vm_collect_usage_func_register = 0;
+    return Qnil;
+}
+
+#else
+
+void (*ruby_vm_collect_usage_func_insn)(int insn) = NULL;
+void (*ruby_vm_collect_usage_func_operand)(int insn, int n, VALUE op) = NULL;
+void (*ruby_vm_collect_usage_func_register)(int reg, int isset) = NULL;
+
+#endif
+
+#if VM_COLLECT_USAGE_DETAILS
+/* @param insn instruction number */
+static void
+vm_collect_usage_insn(int insn)
+{
+    if (RUBY_DTRACE_INSN_ENABLED()) {
+	RUBY_DTRACE_INSN(rb_insns_name(insn));
+    }
+    if (ruby_vm_collect_usage_func_insn)
+	(*ruby_vm_collect_usage_func_insn)(insn);
+}
+
+/* @param insn instruction number
+ * @param n    n-th operand
+ * @param op   operand value
+ */
+static void
+vm_collect_usage_operand(int insn, int n, VALUE op)
+{
+    if (RUBY_DTRACE_INSN_OPERAND_ENABLED()) {
+	VALUE valstr;
+
+	valstr = rb_insn_operand_intern(GET_THREAD()->cfp->iseq, insn, n, op, 0, 0, 0, 0);
+
+	RUBY_DTRACE_INSN_OPERAND(RSTRING_PTR(valstr), rb_insns_name(insn));
+	RB_GC_GUARD(valstr);
+    }
+    if (ruby_vm_collect_usage_func_operand)
+	(*ruby_vm_collect_usage_func_operand)(insn, n, op);
+}
+
+/* @param reg register id. see code of vm_analysis_register() */
+/* @param isset 0: read, 1: write */
+static void
+vm_collect_usage_register(int reg, int isset)
+{
+    if (ruby_vm_collect_usage_func_register)
+	(*ruby_vm_collect_usage_func_register)(reg, isset);
+}
+#endif