enable constant cache on ractors

constant cache `IC` is accessed by non-atomic manner and there are
thread-safety issues, so Ruby 3.0 disables to use const cache on
non-main ractors.

This patch enables it by introducing `imemo_constcache` and allocates
it by every re-fill of const cache like `imemo_callcache`.
[Bug #17510]

Now `IC` only has one entry `IC::entry` and it points to
`iseq_inline_constant_cache_entry`, managed by T_IMEMO object.

`IC` is atomic data structure so `rb_mjit_before_vm_ic_update()` and
`rb_mjit_after_vm_ic_update()` is not needed.

1 files changed, 8 insertions, 5 deletions

diff --git a/tool/ruby_vm/views/_mjit_compile_getinlinecache.erb b/tool/ruby_vm/views/_mjit_compile_getinlinecache.erb
index 44b7f3286a..1b636bceb6 100644
--- a/tool/ruby_vm/views/_mjit_compile_getinlinecache.erb
+++ b/tool/ruby_vm/views/_mjit_compile_getinlinecache.erb
@@ -12,11 +12,13 @@
 % end
 
 % # compiler: Capture IC values, locking getinlinecache
-    rb_mjit_before_vm_ic_update();
-    rb_serial_t ic_serial = ic->ic_serial;
-    const rb_cref_t *ic_cref = ic->ic_cref;
-    VALUE ic_value = ic->value;
-    rb_mjit_after_vm_ic_update();
+    struct iseq_inline_constant_cache_entry *ice = ic->entry;
+    if (ice == NULL) {
+        goto getinlinecache_cancel;
+    }
+    rb_serial_t ic_serial = ice->ic_serial;
+    const rb_cref_t *ic_cref = ice->ic_cref;
+    VALUE ic_value = ice->value;
 
     if (ic_serial && !status->compile_info->disable_const_cache) {
 %       # JIT: Inline everything in IC, and cancel the slow path
@@ -34,3 +36,4 @@
         b->stack_size += <%= insn.call_attribute('sp_inc') %>;
         break;
     }
+    getinlinecache_cancel:;