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, 12 insertions, 0 deletions

diff --git a/bootstraptest/test_ractor.rb b/bootstraptest/test_ractor.rb
index 843714a7bc..56add68403 100644
--- a/bootstraptest/test_ractor.rb
+++ b/bootstraptest/test_ractor.rb
@@ -967,6 +967,18 @@ assert_equal 'can not access non-shareable objects in constant C::CONST by non-m
   end
 }
 
+# Constant cache should care about non-sharable constants
+assert_equal "can not access non-shareable objects in constant Object::STR by non-main Ractor.", %q{
+  STR = "hello"
+  def str; STR; end
+  s = str() # fill const cache
+  begin
+    Ractor.new{ str() }.take
+  rescue Ractor::RemoteError => e
+    e.cause.message
+  end
+}
+
 # Setting non-shareable objects into constants by other Ractors is not allowed
 assert_equal 'can not set constants with non-shareable objects by non-main Ractors', %q{
   class C