Use rb_execution_context_t instead of rb_thread_t

to represent execution context [Feature #14038]

* vm_core.h (rb_thread_t): rb_thread_t::ec is now a pointer.
  There are many code using `th` to represent execution context
  (such as cfp, VM stack and so on). To access `ec`, they need to
  use `th->ec->...` (adding one indirection) so that we need to
  replace them by passing `ec` instead of `th`.

* vm_core.h (GET_EC()): introduced to access current ec. Also
  remove `ruby_current_thread` global variable.

* cont.c (rb_context_t): introduce rb_context_t::thread_ptr instead of
  rb_context_t::thread_value.

* cont.c (ec_set_vm_stack): added to update vm_stack explicitly.

* cont.c (ec_switch): added to switch ec explicitly.

* cont.c (rb_fiber_close): added to terminate fibers explicitly.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60440 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

Author: ko1

.gdbinit

@@ -1119,8 +1119,8 @@ define rb_ps_thread
   set $ps_thread_th = (rb_thread_t*)$ps_thread->data
   printf "* #<Thread:%p rb_thread_t:%p native_thread:%p>\n", \
     $ps_thread, $ps_thread_th, $ps_thread_th->thread_id
-  set $cfp = $ps_thread_th->ec.cfp
-  set $cfpend = (rb_control_frame_t *)($ps_thread_th->ec.vm_stack + $ps_thread_th->ec.vm_stack_size)-1
+  set $cfp = $ps_thread_th->ec->cfp
+  set $cfpend = (rb_control_frame_t *)($ps_thread_th->ec->vm_stack + $ps_thread_th->ec.vm_stack_size)-1
   while $cfp < $cfpend
     if $cfp->iseq
       if !((VALUE)$cfp->iseq & RUBY_IMMEDIATE_MASK) && (((imemo_ifunc << RUBY_FL_USHIFT) | RUBY_T_IMEMO)==$cfp->iseq->flags & ((RUBY_IMEMO_MASK << RUBY_FL_USHIFT) | RUBY_T_MASK))

compile.c

@@ -7604,7 +7604,7 @@ caller_location(VALUE *path, VALUE *realpath)
 {
     const rb_thread_t *const th = GET_THREAD();
     const rb_control_frame_t *const cfp =
-	rb_vm_get_ruby_level_next_cfp(th, th->ec.cfp);
+	rb_vm_get_ruby_level_next_cfp(th, th->ec->cfp);
 
     if (cfp) {
 	int line = rb_vm_get_sourceline(cfp);