No longer need to insert write barriers for fibers.
Those barriers are inserted to fix but all living fibers are
marked from `mark_context()` anyway now.
MODIFY
mrbgems/mruby-fiber/src/fiber.c
mrbgems/mruby-fiber/src/fiber.c
@@ -175,9 +175,6 @@ fiber_check_cfunc(mrb_state *mrb, struct mrb_context *c)
static void
fiber_switch_context(mrb_state *mrb, struct mrb_context *c)
{
- if (mrb->c->fib) {
- mrb_write_barrier(mrb, (struct RBasic*)mrb->c->fib);
- }
c->status = MRB_FIBER_RUNNING;
mrb->c = c;
}

MODIFY
src/vm.c
src/vm.c
@@ -948,12 +948,7 @@ mrb_vm_run(mrb_state *mrb, struct RProc *proc, mrb_value self, unsigned int stac
if (c->ci - c->cibase > cioff) {
c->ci = c->cibase + cioff;
}
- if (mrb->c != c) {
- if (mrb->c->fib) {
- mrb_write_barrier(mrb, (struct RBasic*)mrb->c->fib);
- }
mrb->c = c;
- }
return result;
}
@@ -1945,9 +1940,6 @@ RETRY_TRY_BLOCK:
while (c->eidx > ci->epos) {
ecall_adjust();
}
- if (c->fib) {
- mrb_write_barrier(mrb, (struct RBasic*)c->fib);
- }
mrb->c->status = MRB_FIBER_TERMINATED;
mrb->c = c->prev;
c->prev = NULL;

No longer need to insert write barriers for fibers.

Those barriers are inserted to fix #3699 but all living fibers are
marked from `mark_context()` anyway now.