Unified `pc` and `err` of `mrb_callinfo`

This enhances self-containment.

- Changed the `mrb_callinfo::pc` field to point to itself.
  Previously it indicated the return destination of the previous call level.
  `mrb_callinfo::pc` will now hold the address to its own `proc->body.irep->iseq`.
- Removed `mrb_callinfo::err` field.
  This is because `mrb_callinfo::pc - 1` is semantically the same as the previous `err`.
- The `pc0` and `pc_save` variables in `mrb_vm_exec()` are no longer needed and have been deleted.
- It removes the argument because `cipush()` doesn't need to save the previous `pc`.

1 files changed, 1 insertions, 2 deletions

diff --git a/mrbgems/mruby-fiber/src/fiber.c b/mrbgems/mruby-fiber/src/fiber.c
index d75f864c1..7fd755843 100644
--- a/mrbgems/mruby-fiber/src/fiber.c
+++ b/mrbgems/mruby-fiber/src/fiber.c
@@ -119,9 +119,8 @@ fiber_init(mrb_state *mrb, mrb_value self)
   /* adjust return callinfo */
   ci = c->ci;
   mrb_vm_ci_target_class_set(ci, MRB_PROC_TARGET_CLASS(p));
-  ci->proc = p;
+  mrb_vm_ci_proc_set(ci, p);
   mrb_field_write_barrier(mrb, (struct RBasic*)mrb_obj_ptr(self), (struct RBasic*)p);
-  ci->pc = p->body.irep->iseq;
   ci->stack = c->stbase;
   ci[1] = ci[0];
   c->ci++;                      /* push dummy callinfo */