From: Mike Owens <mikeowens@...>
Date: 2013-03-17T01:51:16+09:00
Subject: Re: RubyVM::InstructionSequence compiling and loading

There is a single line difference between the two sequences:

44c44
< {:mid=>:collect, :flag=>0, :orig_argc=>0,
:blockptr=>["YARVInstructionSequence/SimpleDataFormat", 2, 0, 1,
{:arg_size=>1, :local_size=>2, :stack_max=>4}, "block in <compiled>",
"<compiled>", nil, 4, :block, [:x], [1, [], 0, 0, -1, -1, 3], [[:redo,
nil, :label_0, :label_22, :label_0, 0], [:next, nil, :label_0,
:label_22, :label_22, 0]], [:label_0, [:trace, 256], [:trace, 1],
[:getlocal_OP__WC__0, 2], [:putobject_OP_INT2FIX_O_0_C_], [:opt_aref,
{:mid=>:[], :flag=>256, :orig_argc=>1, :blockptr=>nil}], [:tostring],
[:putobject, "="], [:getlocal_OP__WC__0, 2],
[:putobject_OP_INT2FIX_O_1_C_], [:opt_aref, {:mid=>:[], :flag=>256,
:orig_argc=>1, :blockptr=>nil}], [:tostring], [:concatstrings, 3],
[:trace, 512], :label_22, [:leave]]]}
---
> {:mid=>:collect, :flag=>256, :orig_argc=>0, :blockptr=>nil}

Since I don't have the first clue as to how this part of Ruby works
I'll just move wait until iseq_s_load() is officially supported.

On Sat, Mar 16, 2013 at 11:03 AM, Mike Owens <mikeowens@gmail.com> wrote:
> Actually a better example without having to recompile Ruby is the following:
>
> #!/usr/bin/env ruby
>
> require 'fiddle'
>
> class RubyVM
>   class InstructionSequence
>     address = Fiddle::Handle::DEFAULT['rb_iseq_load']
>     func = Fiddle::Function.new( address,
>                                  [Fiddle::TYPE_VOIDP] * 3,
>                                  Fiddle::TYPE_VOIDP )
>
>     define_singleton_method(:load) do |data, parent = nil, opt = nil|
>       func.call(Fiddle.dlwrap(data), parent, opt).to_value
>     end
>   end
> end
>
> source = %q{
>   args           = {}
>   args['q']      = 'test'
>   args.to_a.collect {|x| "#{x[0]}=#{x[1]}" }.join('&')
> }
>
> orig   = RubyVM::InstructionSequence.new source
> loaded = RubyVM::InstructionSequence.load orig.to_a
>
> orig.eval
> loaded.eval
>
> The last eval throws the exception. It would seem like the two
> instruction sequences should be equivalent.
>
> On Fri, Mar 15, 2013 at 11:53 PM, Mike Owens <mikeowens@gmail.com> wrote:
>> I recently came across "An Amateur Smalltalk User's Observations on
>> Ruby Object Model and Bytecode"
>> (http://www.slideshare.net/kstan2/smalltalk-and-ruby-20121208-15542185).
>> I tried his example of enabling iseq_s_load(). I stumbled across a
>> simple case where the loaded compiled code does not work as the
>> original compiled code, specifically:
>>
>>     source = %q{
>>     args           = {}
>>     args['q']      = 'test'
>>     args.to_a.collect {|x| "#{x[0]}=#{x[1]}" }.join('&')
>>   }
>>
>>   orig = RubyVM::InstructionSequence.compile source
>>   loaded = RubyVM::InstructionSequence.load ins.to_a
>>
>>   orig.eval
>>   other.eval  # <- Exception
>>
>> The first eval works. The second eval throws an exception:
>>
>>   <compiled>:in `<compiled>': undefined method `join' for
>> #<Enumerator: [["q", "test"]]:collect> (NoMethodError)
>>
>> The result of the first collect method is (and should be) an Array.
>> However the second is producing an Enumerator.
>>
>> I was wondering if anyone could explain why this is the case?
>>
>> --
>> Mike
>>
>
>
>
> --
> Mike
>



-- 
Mike