Issue #8543 has been updated by Eric Wong.


 nop; nop works, but I don't think it's an improvement (or regression).
 I prefer to save 2 words entirely.
 
 I planned to workaround the issue by doing ISeq#load twice:
 
    first = iseq.to_a       # useless jump|nop here
    junk = ISeq.load(first) # second pass optimization removes jump|nop
    a = ISeq.load(junk.to_a)
    b = ISeq.load(a.to_a)
    assert_equal a, b
 
 But I encountered other bugs with to_a + load on test/ruby/test_io.rb
 and test_settracefunc.rb which I have not investigated, yet...
 
 Works-in-progress:
 
 [PATCH 1/2] http://80x24.org/spew/m/iseq_calc_param_size%40r48578.txt
 [PATCH 2/2] http://80x24.org/spew/m/rb_iseq_load_fix-v4%40r48578.txt

----------------------------------------
Feature #8543: rb_iseq_load
https://bugs.ruby-lang.org/issues/8543#change-50094

* Author: Alexey Voskov
* Status: Open
* Priority: Low
* Assignee: Koichi Sasada
* Category: YARV
* Target version: current: 2.2.0
----------------------------------------
I noticed an unusual behaviour of undocumented rb_iseq_load function. 
Its work differs in different Ruby versions. I'm trying to protect some Ruby
source code by its conversion to YARV p-code and using the next strategy:

1. Convert code to array

   ~~~ruby
   data = RubyVM::InstructionSequence.compile_file('hello.rb').to_a
   ~~~

2. Pass a compiled source to the rb_iseq_load function and evaluate it

   ~~~ruby
   iseq = iseq_load.(data)
   iseq.eval
   ~~~

Sample programs are supplied in the attachments.
"hello.rb"

```ruby
puts "tralivali"
def funct(a,b)
  a**b
end

3.times { |i|
  puts "Hello, world#{funct(2,i)}!"
}
```

The differences
Ruby 1.9.3 (ruby 1.9.3p194 (2012-04-20) [i386-mingw32])
Correct work. Output:

```
tralivali
Hello, world1!
Hello, world2!
Hello, world4!
```

Ruby 2.0.0 (ruby 2.0.0p193 (2013-05-14) [x64-mingw32])
Incorrect work (omits the code inside code blocks). Output

```
tralivali
```

Attempts of loading bigger programs by means of rb_iseq_load in Ruby 2.0.0 usually ends with a segmentation fault.

Such behaviour also can be reproduced by means of iseq Ruby extension ("for iseq freaks")
https://github.com/wanabe/iseq

P.S. I understand that it is an undocumented feature.


---Files--------------------------------
hello.rb (102 Bytes)
rb_pack.rb (931 Bytes)
iseq-load-test3.rb (210 Bytes)
iseq-load-test3-file.rb (369 Bytes)
please-fix-rb_iseq_load-thank-you.pdf (444 KB)


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