Enable FrozenCore monkey-patching bytecode

frozen_core.rb

# frozen_string_literal: true

abort 'MJIT needs to be enabled' unless RubyVM::MJIT.enabled?

# make private constants available at top-level
# 
constants = 
  Symbol.all_symbols.select do                                               
    RubyVM::MJIT.private_constant _1 rescue next                                
  end

constants.each { Object.const_set _1, RubyVM::MJIT.const_get(_1) }

  
# dummy method to append iseq
#
def dummy = nil

# find the instructions we need
#
instructions = INSNS.values.select { _1.name =~ /\A(putspecialobject|leave)/ }

# get bytecode object
#
iseq = RubyVM::InstructionSequence.of method(:dummy)

# get pointer for iseq
#
iseq_ptr = C.rb_iseqw_to_iseq iseq

# build the method
#
iseq_ptr.body.iseq_encoded[0] = C.rb_vm_insn_encode instructions[0].bin
iseq_ptr.body.iseq_encoded[1] = 1 # FrozenCore enum type
iseq_ptr.body.iseq_encoded[2] = C.rb_vm_insn_encode instructions[1].bin

FC = dummy

p FC.singleton_methods

__END__

=> [:"core#set_variable_alias",
   :"core#undef_method",
   :make_shareable,
   :make_shareable_copy,
   :"core#set_postexe",
   :"core#hash_merge_ptr",
   :"core#hash_merge_kwd",
   :"core#raise",
   :"core#sprintf",
   :"core#set_method_alias",
   :ensure_shareable,
   :proc,
   :lambda]