* vm.c: add RubyVM::Backtrace object (btobj).

  Backtrace information contains an array consists of location
  information for each frames by string.
  RubyVM::Backtrace object is lightweight backtrace information,
  which contains complete information to generate traditional style
  backtrace (an array of strings) with faster generation.
  If someone accesses to backtrace information via
  Exception#backtrace, then convert a RubyVM::Backtrace object to
  traditonal style backtrace.
  This change causes incompatibility on marshal dumpped binary
  of Exception.  If you have any trouble on it, please tell us
  before Ruby 2.0 release.
  Note that RubyVM::Backtrace object should not expose Ruby level.
* error.c, eval.c, vm_eval.c: ditto.
* internal.h: ditto.
* eval_error.c: fix to skip "set_backtrace" method invocation in
  creating an exception object if it call a normal set_backtrace
  method (defined by core).
* test/ruby/test_settracefunc.rb: fix for above change.
* vm_method.c (rb_method_defined_by): added.  This function
  checks that the given object responds with the given method
  by the given cfunc.
* benchmark/bm_vm2_raise1.rb, benchmark/bm_vm2_raise2.rb:
  add to measure exception creation speed. raise1 create
  exception objects from shallow stack frame.  raise2 create
  exception objects from deep stack frame.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@35769 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

11 files changed, 426 insertions, 28 deletions

diff --git a/ChangeLog b/ChangeLog
index a06b5be2f4..655bac0555 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,38 @@
+Thu May 24 14:30:13 2012  Koichi Sasada  <ko1@atdot.net>
+
+	* vm.c: add RubyVM::Backtrace object (btobj).
+	  Backtrace information contains an array consists of location 
+          information for each frames by string.
+	  RubyVM::Backtrace object is lightweight backtrace information,
+	  which contains complete information to generate traditional style
+	  backtrace (an array of strings) with faster generation.
+	  If someone accesses to backtrace information via
+	  Exception#backtrace, then convert a RubyVM::Backtrace object to
+	  traditonal style backtrace.
+	  This change causes incompatibility on marshal dumpped binary
+	  of Exception.  If you have any trouble on it, please tell us
+	  before Ruby 2.0 release.
+	  Note that RubyVM::Backtrace object should not expose Ruby level.
+
+	* error.c, eval.c, vm_eval.c: ditto.
+
+	* internal.h: ditto.
+
+	* eval_error.c: fix to skip "set_backtrace" method invocation in
+	  creating an exception object if it call a normal set_backtrace
+	  method (defined by core).
+
+	* test/ruby/test_settracefunc.rb: fix for above change.
+
+	* vm_method.c (rb_method_defined_by): added.  This function 
+	  checks that the given object responds with the given method
+	  by the given cfunc.
+
+	* benchmark/bm_vm2_raise1.rb, benchmark/bm_vm2_raise2.rb: 
+	  add to measure exception creation speed. raise1 create
+	  exception objects from shallow stack frame.  raise2 create
+	  exception objects from deep stack frame.
+
 Thu May 24 12:07:46 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* io.c (io_strip_bom): check EOF.  [Bug #6487][ruby-core:45203]
diff --git a/benchmark/bm_vm2_raise1.rb b/benchmark/bm_vm2_raise1.rb
new file mode 100644
index 0000000000..b3d9c3a8a4
--- /dev/null
+++ b/benchmark/bm_vm2_raise1.rb
@@ -0,0 +1,18 @@
+def rec n
+  if n > 0
+    rec n-1
+  else
+    raise
+  end
+end
+
+i=0
+while i<6_000_000 # benchmark loop 2
+  i+=1
+
+  begin
+    rec 1
+  rescue
+    # ignore
+  end
+end
diff --git a/benchmark/bm_vm2_raise2.rb b/benchmark/bm_vm2_raise2.rb
new file mode 100644
index 0000000000..3f1e8dc1c7
--- /dev/null
+++ b/benchmark/bm_vm2_raise2.rb
@@ -0,0 +1,18 @@
+def rec n
+  if n > 0
+    rec n-1
+  else
+    raise
+  end
+end
+
+i=0
+while i<6_000_000 # benchmark loop 2
+  i+=1
+
+  begin
+    rec 10
+  rescue
+    # ignore
+  end
+end
diff --git a/error.c b/error.c
index 90f04829f9..1be043057a 100644
--- a/error.c
+++ b/error.c
@@ -673,9 +673,17 @@ static VALUE
 exc_backtrace(VALUE exc)
 {
     ID bt;
+    VALUE obj;
 
     CONST_ID(bt, "bt");
-    return rb_attr_get(exc, bt);
+    obj = rb_attr_get(exc, bt);
+
+    if (rb_backtrace_p(obj)) {
+	obj = rb_backtrace_to_str_ary(obj);
+	/* rb_iv_set(exc, "bt", obj); */
+    }
+
+    return obj;
 }
 
 VALUE
@@ -686,6 +694,7 @@ rb_check_backtrace(VALUE bt)
 
     if (!NIL_P(bt)) {
 	if (RB_TYPE_P(bt, T_STRING)) return rb_ary_new3(1, bt);
+	if (rb_backtrace_p(bt)) return bt;
 	if (!RB_TYPE_P(bt, T_ARRAY)) {
 	    rb_raise(rb_eTypeError, err);
 	}
@@ -708,8 +717,8 @@ rb_check_backtrace(VALUE bt)
  *
  */
 
-static VALUE
-exc_set_backtrace(VALUE exc, VALUE bt)
+VALUE
+rb_exc_set_backtrace(VALUE exc, VALUE bt)
 {
     return rb_iv_set(exc, "bt", rb_check_backtrace(bt));
 }
@@ -1669,7 +1678,7 @@ Init_Exception(void)
     rb_define_method(rb_eException, "message", exc_message, 0);
     rb_define_method(rb_eException, "inspect", exc_inspect, 0);
     rb_define_method(rb_eException, "backtrace", exc_backtrace, 0);
-    rb_define_method(rb_eException, "set_backtrace", exc_set_backtrace, 1);
+    rb_define_method(rb_eException, "set_backtrace", rb_exc_set_backtrace, 1);
 
     rb_eSystemExit  = rb_define_class("SystemExit", rb_eException);
     rb_define_method(rb_eSystemExit, "initialize", exit_initialize, -1);
diff --git a/eval.c b/eval.c
index 75dca74be3..298326a556 100644
--- a/eval.c
+++ b/eval.c
@@ -387,7 +387,7 @@ setup_exception(rb_thread_t *th, int tag, volatile VALUE mesg)
 	else {
 	    at = get_backtrace(mesg);
 	    if (NIL_P(at)) {
-		at = rb_make_backtrace();
+		at = rb_vm_backtrace_object();
 		if (OBJ_FROZEN(mesg)) {
 		    mesg = rb_obj_dup(mesg);
 		}
diff --git a/eval_error.c b/eval_error.c
index e7eb9cf0fc..a2e95a759f 100644
--- a/eval_error.c
+++ b/eval_error.c
@@ -58,6 +58,17 @@ rb_get_backtrace(VALUE info)
 static void
 set_backtrace(VALUE info, VALUE bt)
 {
+    ID set_backtrace = rb_intern("set_backtrace");
+
+    if (rb_backtrace_p(bt)) {
+	if (rb_method_defined_by(info, set_backtrace, rb_exc_set_backtrace)) {
+	    rb_exc_set_backtrace(info, bt);
+	    return;
+	}
+	else {
+	    bt = rb_backtrace_to_str_ary(bt);
+	}
+    }
     rb_funcall(info, rb_intern("set_backtrace"), 1, bt);
 }
 
diff --git a/internal.h b/internal.h
index e5818429ea..6ba8e1f3b0 100644
--- a/internal.h
+++ b/internal.h
@@ -83,6 +83,7 @@ void rb_gc_mark_encodings(void);
 NORETURN(PRINTF_ARGS(void rb_compile_bug(const char*, int, const char*, ...), 3, 4));
 VALUE rb_check_backtrace(VALUE);
 NORETURN(void rb_async_bug_errno(const char *,int));
+VALUE rb_exc_set_backtrace(VALUE exc, VALUE bt);
 
 /* eval_error.c */
 void ruby_error_print(void);
@@ -207,6 +208,9 @@ void rb_vm_inc_const_missing_count(void);
 void rb_thread_mark(void *th);
 const void **rb_vm_get_insns_address_table(void);
 VALUE rb_sourcefilename(void);
+int rb_backtrace_p(VALUE obj);
+VALUE rb_backtrace_to_str_ary(VALUE obj);
+VALUE rb_vm_backtrace_object();
 
 /* vm_dump.c */
 void rb_vm_bugreport(void);
@@ -217,6 +221,7 @@ VALUE rb_current_realfilepath(void);
 
 /* vm_method.c */
 void Init_eval_method(void);
+int rb_method_defined_by(VALUE obj, ID mid, VALUE (*cfunc)(ANYARGS));
 
 /* miniprelude.c, prelude.c */
 void Init_prelude(void);
diff --git a/test/ruby/test_settracefunc.rb b/test/ruby/test_settracefunc.rb
index 32be12814b..463923aa26 100644
--- a/test/ruby/test_settracefunc.rb
+++ b/test/ruby/test_settracefunc.rb
@@ -250,10 +250,6 @@ class TestSetTraceFunc < Test::Unit::TestCase
                  events.shift)
     assert_equal(["c-return", 5, :backtrace, Exception],
                  events.shift)
-    assert_equal(["c-call", 5, :set_backtrace, Exception],
-                 events.shift)
-    assert_equal(["c-return", 5, :set_backtrace, Exception],
-                 events.shift)
     assert_equal(["raise", 5, :test_raise, TestSetTraceFunc],
                  events.shift)
     assert_equal(["c-return", 5, :raise, Kernel],
diff --git a/vm.c b/vm.c
index dea51a2911..0898deac92 100644
--- a/vm.c
+++ b/vm.c
@@ -36,14 +36,16 @@ VALUE rb_cRubyVM;
 VALUE rb_cThread;
 VALUE rb_cEnv;
 VALUE rb_mRubyVMFrozenCore;
+VALUE rb_cBacktrace;
+VALUE rb_cFrameInfo;
 
 VALUE ruby_vm_const_missing_count = 0;
-
 char ruby_vm_redefined_flag[BOP_LAST_];
-
 rb_thread_t *ruby_current_thread = 0;
 rb_vm_t *ruby_current_vm = 0;
 
+extern VALUE ruby_engine_name;
+
 static void thread_free(void *ptr);
 
 void vm_analysis_operand(int insn, int n, VALUE op);
@@ -731,6 +733,12 @@ rb_lastline_set(VALUE val)
 
 /* backtrace */
 
+inline static int
+calc_line_no(const rb_iseq_t *iseq, VALUE *pc)
+{
+    return rb_iseq_line_no(iseq, pc - iseq->iseq_encoded);
+}
+
 int
 rb_vm_get_sourceline(const rb_control_frame_t *cfp)
 {
@@ -738,22 +746,289 @@ rb_vm_get_sourceline(const rb_control_frame_t *cfp)
     const rb_iseq_t *iseq = cfp->iseq;
 
     if (RUBY_VM_NORMAL_ISEQ_P(iseq)) {
-	size_t pos = cfp->pc - cfp->iseq->iseq_encoded;
-	line_no = rb_iseq_line_no(iseq, pos);
+	line_no = calc_line_no(cfp->iseq, cfp->pc);
     }
     return line_no;
 }
 
+typedef struct rb_frame_info_struct {
+    enum FRAME_INFO_TYPE {
+	FRAME_INFO_TYPE_ISEQ = 1,
+	FRAME_INFO_TYPE_CFUNC,
+	FRAME_INFO_TYPE_IFUNC,
+    } type;
+
+    union {
+	struct {
+	    rb_iseq_t *iseq;
+	    VALUE *pc;
+	} iseq;
+	struct {
+	    ID mid;
+	} cfunc;
+    } body;
+} rb_frame_info_t;
+
+static void
+frame_info_mark(void *ptr)
+{
+    if (ptr) {
+	rb_frame_info_t *fi = (rb_frame_info_t *)ptr;
+
+	switch (fi->type) {
+	  case FRAME_INFO_TYPE_ISEQ:
+	    rb_gc_mark(fi->body.iseq.iseq->self);
+	    break;
+	  case FRAME_INFO_TYPE_CFUNC:
+	  case FRAME_INFO_TYPE_IFUNC:
+	  default:
+	    break;
+	}
+    }
+}
+
+static VALUE
+frame_info_format(VALUE file, VALUE line_no, VALUE name)
+{
+    if (line_no != INT2FIX(0)) {
+	return rb_enc_sprintf(rb_enc_compatible(file, name), "%s:%d:in `%s'",
+			      RSTRING_PTR(file), FIX2INT(line_no), RSTRING_PTR(name));
+    }
+    else {
+	return rb_enc_sprintf(rb_enc_compatible(file, name), "%s:in `%s'",
+			      RSTRING_PTR(file), RSTRING_PTR(name));
+    }
+}
+
+static VALUE
+frame_info_to_str_override(rb_frame_info_t *fi, VALUE *args)
+{
+    switch (fi->type) {
+      case FRAME_INFO_TYPE_ISEQ: 
+	args[0] = fi->body.iseq.iseq->location.filename;
+	args[1] = INT2FIX(calc_line_no(fi->body.iseq.iseq, fi->body.iseq.pc));
+	args[2] = fi->body.iseq.iseq->location.name;
+	break;
+      case FRAME_INFO_TYPE_CFUNC:
+	args[2] = rb_id2str(fi->body.cfunc.mid);
+	break;
+      case FRAME_INFO_TYPE_IFUNC:
+      default:
+	rb_bug("frame_info_to_str_overwrite: unreachable");
+    }
+
+    return frame_info_format(args[0], args[1], args[2]);
+}
+
+typedef struct rb_backtrace_struct {
+    rb_frame_info_t *backtrace;
+    int backtrace_size;
+    VALUE str;
+} rb_backtrace_t;
+
+static void
+backtrace_mark(void *ptr)
+{
+    if (ptr) {
+	rb_backtrace_t *bt = (rb_backtrace_t *)ptr;
+	int i, s = bt->backtrace_size;
+
+	for (i=0; i<s; i++) {
+	    frame_info_mark(&bt->backtrace[i]);
+	    rb_gc_mark(bt->str);
+	}
+    }
+}
+
+static void
+backtrace_free(void *ptr)
+{
+   if (ptr) {
+       rb_backtrace_t *bt = (rb_backtrace_t *)ptr;
+       if (bt->backtrace) ruby_xfree(bt->backtrace);
+       ruby_xfree(bt);
+   }
+}
+
+static size_t
+backtrace_memsize(const void *ptr)
+{
+    rb_backtrace_t *bt = (rb_backtrace_t *)ptr;
+    return sizeof(rb_backtrace_t) + sizeof(rb_frame_info_t) * bt->backtrace_size;
+}
+
+static const rb_data_type_t backtrace_data_type = {
+    "backtrace",
+    {backtrace_mark, backtrace_free, backtrace_memsize,},
+};
+
+int
+rb_backtrace_p(VALUE obj)
+{
+    if (TYPE(obj) == T_DATA && RTYPEDDATA_P(obj) && RTYPEDDATA_TYPE(obj) == &backtrace_data_type) {
+	return 1;
+    }
+    else {
+	return 0;
+    }
+}
+
+static VALUE
+backtrace_alloc(VALUE klass)
+{
+    rb_backtrace_t *bt;
+    VALUE obj = TypedData_Make_Struct(klass, rb_backtrace_t, &backtrace_data_type, bt);
+    bt->backtrace = 0;
+    bt->backtrace_size = 0;
+    bt->str = 0;
+    return obj;
+}
+
+static VALUE
+backtrace_object(rb_thread_t *th, int lev, int n)
+{
+    VALUE btobj = backtrace_alloc(rb_cBacktrace);
+    rb_backtrace_t *bt;
+    rb_control_frame_t *last_cfp = th->cfp;
+    rb_control_frame_t *start_cfp = RUBY_VM_END_CONTROL_FRAME(th);
+    rb_control_frame_t *cfp;
+    int size, i, j;
+
+    start_cfp = RUBY_VM_NEXT_CONTROL_FRAME(
+	RUBY_VM_NEXT_CONTROL_FRAME(
+	    RUBY_VM_NEXT_CONTROL_FRAME(start_cfp))); /* skip top frames */
+    size = (start_cfp - last_cfp) + 1;
+
+    if (n <= 0) {
+	n = size + n;
+	if (n < 0) {
+	    n = 0;
+	}
+    }
+    if (lev < 0) {
+	lev = 0;
+    }
+
+    GetCoreDataFromValue(btobj, rb_backtrace_t, bt);
+    bt->backtrace = ruby_xmalloc(sizeof(rb_frame_info_t) * n);
+    bt->backtrace_size = n;
+
+    for (i=lev, j=0, cfp = start_cfp; i<size && j<n; i++, cfp = RUBY_VM_NEXT_CONTROL_FRAME(cfp)) {
+	rb_frame_info_t *fi = &bt->backtrace[j];
+
+	if (cfp->iseq) {
+	    if (cfp->pc) {
+		fi->type = FRAME_INFO_TYPE_ISEQ;
+		fi->body.iseq.iseq = cfp->iseq;
+		fi->body.iseq.pc = cfp->pc;
+		j++;
+	    }
+	}
+	else if (RUBYVM_CFUNC_FRAME_P(cfp)) {
+	    ID mid = cfp->me->def ? cfp->me->def->original_id : cfp->me->called_id;
+
+	    if (mid != ID_ALLOCATOR) {
+		fi->type = FRAME_INFO_TYPE_CFUNC;
+		fi->body.cfunc.mid = mid;
+		j++;
+	    }
+	}
+    }
+
+    if (j > 0) {
+	bt->backtrace_size = j; /* TODO: realloc? */
+	return btobj;
+    }
+    else {
+	/* gc will free object */
+	return Qnil;
+    }
+}
+
+static VALUE
+backtreace_collect(rb_backtrace_t *bt, VALUE (*func)(rb_frame_info_t *, VALUE *))
+{
+    VALUE btary;
+    int i;
+    VALUE args[3];
+    rb_thread_t *th = GET_THREAD();
+
+    btary = rb_ary_new2(bt->backtrace_size);
+    rb_ary_store(btary, bt->backtrace_size-1, Qnil); /* create places */
+
+    args[0] = th->vm->progname ? th->vm->progname : ruby_engine_name;;
+    args[1] = INT2FIX(0);
+    args[2] = Qnil;
+
+    for (i=0; i<bt->backtrace_size; i++) {
+	rb_frame_info_t *fi = &bt->backtrace[i];
+	RARRAY_PTR(btary)[bt->backtrace_size - i - 1] = func(fi, args);
+    }
+
+    return btary;
+}
+
+VALUE
+rb_backtrace_to_str_ary(VALUE self)
+{
+    rb_backtrace_t *bt;
+    GetCoreDataFromValue(self, rb_backtrace_t, bt);
+
+    if (bt->str) {
+	return bt->str;
+    }
+    else {
+	bt->str = backtreace_collect(bt, frame_info_to_str_override);
+	return bt->str;
+    }
+}
+
+#if 0
+static VALUE
+rb_backtrace_to_frame_ary(VALUE self)
+{
+    return backtreace_collect(self, frame_info_create);
+}
+
+static VALUE
+vm_backtrace_frame_ary(rb_thread_t *th, int lev, int n)
+{
+    return rb_backtrace_to_frame_ary(vm_backtrace_create(th, lev, n));
+}
+#endif
+
+static VALUE
+backtrace_dump_data(VALUE self)
+{
+    VALUE str = rb_backtrace_to_str_ary(self);
+    return str;
+}
+
+static VALUE
+backtrace_load_data(VALUE self, VALUE str)
+{
+    rb_backtrace_t *bt;
+    GetCoreDataFromValue(self, rb_backtrace_t, bt);
+    bt->str = str;
+    return self;
+}
+
+/* old style backtrace for compatibility */
+
 static int
-vm_backtrace_each(rb_thread_t *th, int lev, void (*init)(void *), rb_backtrace_iter_func *iter, void *arg)
+vm_backtrace_each(rb_thread_t *th, int lev, int n, void (*init)(void *), rb_backtrace_iter_func *iter, void *arg)
 {
     const rb_control_frame_t *limit_cfp = th->cfp;
     const rb_control_frame_t *cfp = (void *)(th->stack + th->stack_size);
     VALUE file = Qnil;
     int line_no = 0;
 
+    if (n <= 0) {
+	n = cfp - limit_cfp;
+    }
+
     cfp -= 2;
-    while (lev-- >= 0) {
+    while (lev-- >= 0 && n > 0) {
 	if (++limit_cfp > cfp) {
 	    return FALSE;
 	}
@@ -761,20 +1036,21 @@ vm_backtrace_each(rb_thread_t *th, int lev, void (*init)(void *), rb_backtrace_i
     if (init) (*init)(arg);
     limit_cfp = RUBY_VM_NEXT_CONTROL_FRAME(limit_cfp);
     if (th->vm->progname) file = th->vm->progname;
-    while (cfp > limit_cfp) {
+    while (cfp > limit_cfp && n>0) {
 	if (cfp->iseq != 0) {
 	    if (cfp->pc != 0) {
 		rb_iseq_t *iseq = cfp->iseq;
 
 		line_no = rb_vm_get_sourceline(cfp);
 		file = iseq->location.filename;
+		n--;
 		if ((*iter)(arg, file, line_no, iseq->location.name)) break;
 	    }
 	}
 	else if (RUBYVM_CFUNC_FRAME_P(cfp)) {
 	    ID id;
-	    extern VALUE ruby_engine_name;
 
+	    n--;
 	    if (NIL_P(file)) file = ruby_engine_name;
 	    if (cfp->me->def)
 		id = cfp->me->def->original_id;
@@ -813,15 +1089,15 @@ vm_backtrace_push(void *arg, VALUE file, int line_no, VALUE name)
     return 0;
 }
 
-static inline VALUE
-vm_backtrace(rb_thread_t *th, int lev)
+static VALUE
+vm_backtrace_str_ary(rb_thread_t *th, int lev, int n)
 {
     VALUE ary = 0;
 
     if (lev < 0) {
 	ary = rb_ary_new();
     }
-    vm_backtrace_each(th, lev, vm_backtrace_alloc, vm_backtrace_push, &ary);
+    vm_backtrace_each(th, lev, 0, vm_backtrace_alloc, vm_backtrace_push, &ary);
     if (!ary) return Qnil;
     return rb_ary_reverse(ary);
 }
@@ -2172,6 +2448,13 @@ Init_VM(void)
     rb_cThread = rb_define_class("Thread", rb_cObject);
     rb_undef_alloc_func(rb_cThread);
 
+    /* ::RubyVM::Backtrace */
+    rb_cBacktrace = rb_define_class_under(rb_cRubyVM, "Backtrace", rb_cObject);
+    rb_define_alloc_func(rb_cBacktrace, backtrace_alloc);
+    rb_undef_method(CLASS_OF(rb_cFrameInfo), "new");
+    rb_define_method(rb_cBacktrace, "_dump_data", backtrace_dump_data, 0);
+    rb_define_method(rb_cBacktrace, "_load_data", backtrace_load_data, 1);
+
     /* ::RubyVM::USAGE_ANALYSIS_* */
     rb_define_const(rb_cRubyVM, "USAGE_ANALYSIS_INSN", rb_hash_new());
     rb_define_const(rb_cRubyVM, "USAGE_ANALYSIS_REGS", rb_hash_new());
diff --git a/vm_eval.c b/vm_eval.c
index 8d6c91a158..340abfc610 100644
--- a/vm_eval.c
+++ b/vm_eval.c
@@ -15,13 +15,15 @@ static inline VALUE method_missing(VALUE obj, ID id, int argc, const VALUE *argv
 static inline VALUE rb_vm_set_finish_env(rb_thread_t * th);
 static inline VALUE vm_yield_with_cref(rb_thread_t *th, int argc, const VALUE *argv, const NODE *cref);
 static inline VALUE vm_yield(rb_thread_t *th, int argc, const VALUE *argv);
-static inline VALUE vm_backtrace(rb_thread_t *th, int lev);
-static int vm_backtrace_each(rb_thread_t *th, int lev, void (*init)(void *), rb_backtrace_iter_func *iter, void *arg);
 static NODE *vm_cref_push(rb_thread_t *th, VALUE klass, int noex, rb_block_t *blockptr);
 static VALUE vm_exec(rb_thread_t *th);
 static void vm_set_eval_stack(rb_thread_t * th, VALUE iseqval, const NODE *cref);
 static int vm_collect_local_variables_in_heap(rb_thread_t *th, VALUE *dfp, VALUE ary);
 
+static int vm_backtrace_each(rb_thread_t *th, int lev, int n, void (*init)(void *), rb_backtrace_iter_func *iter, void *arg);
+static VALUE backtrace_object(rb_thread_t *th, int lev, int n);
+static VALUE vm_backtrace_str_ary(rb_thread_t *th, int lev, int n);
+
 typedef enum call_type {
     CALL_PUBLIC,
     CALL_FCALL,
@@ -1085,7 +1087,7 @@ eval_string_with_cref(VALUE self, VALUE src, VALUE scope, NODE *cref, const char
 		errat = rb_get_backtrace(errinfo);
 		mesg = rb_attr_get(errinfo, id_mesg);
 		if (!NIL_P(errat) && RB_TYPE_P(errat, T_ARRAY) &&
-		    (bt2 = vm_backtrace(th, -2), RARRAY_LEN(bt2) > 0)) {
+		    (bt2 = vm_backtrace_str_ary(th, -2, 0), RARRAY_LEN(bt2) > 0)) {
 		    if (!NIL_P(mesg) && RB_TYPE_P(mesg, T_STRING) && !RSTRING_LEN(mesg)) {
 			if (OBJ_FROZEN(mesg)) {
 			    VALUE m = rb_str_cat(rb_str_dup(RARRAY_PTR(errat)[0]), ": ", 2);
@@ -1620,7 +1622,7 @@ rb_f_caller(int argc, VALUE *argv)
     if (lev < 0)
 	rb_raise(rb_eArgError, "negative level (%d)", lev);
 
-    return vm_backtrace(GET_THREAD(), lev);
+    return vm_backtrace_str_ary(GET_THREAD(), lev, 0);
 }
 
 static int
@@ -1642,13 +1644,19 @@ print_backtrace(void *arg, VALUE file, int line, VALUE method)
 void
 rb_backtrace(void)
 {
-    vm_backtrace_each(GET_THREAD(), -1, NULL, print_backtrace, stderr);
+    vm_backtrace_each(GET_THREAD(), -1, 0, NULL, print_backtrace, stderr);
 }
 
 VALUE
 rb_make_backtrace(void)
 {
-    return vm_backtrace(GET_THREAD(), -1);
+    return vm_backtrace_str_ary(GET_THREAD(), -1, 0);
+}
+
+VALUE
+rb_vm_backtrace_object()
+{
+    return backtrace_object(GET_THREAD(), -1, 0);
 }
 
 VALUE
@@ -1667,13 +1675,13 @@ rb_thread_backtrace(VALUE thval)
 	return Qnil;
     }
 
-    return vm_backtrace(th, 0);
+    return vm_backtrace_str_ary(th, 0, 0);
 }
 
 int
 rb_backtrace_each(rb_backtrace_iter_func *iter, void *arg)
 {
-    return vm_backtrace_each(GET_THREAD(), -1, NULL, iter, arg);
+    return vm_backtrace_each(GET_THREAD(), -1, 0, NULL, iter, arg);
 }
 
 /*
diff --git a/vm_method.c b/vm_method.c
index f3da623347..8c606d410c 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -1402,3 +1402,18 @@ Init_eval_method(void)
     }
 }
 
+int
+rb_method_defined_by(VALUE obj, ID mid, VALUE (*cfunc)(ANYARGS))
+{
+    rb_method_entry_t *me = search_method(CLASS_OF(obj), mid);
+
+    if (me && me->def &&
+	me->def->type == VM_METHOD_TYPE_CFUNC &&
+	me->def->body.cfunc.func == cfunc) {
+	return 1;
+    }
+    else {
+	return 0;
+    }
+}
+