[ruby-core:66467] [ruby-trunk - Feature #8543] rb_iseq_load

Issue #8543 has been updated by Eric Wong.


 ko1: thank you for checking, any comment on the extra jumps insns which
 I hack around by disabling peephole optimization?
 
 It seems caused by the following in iseq_set_sequence:
 
 		    else if (orig_sp - sp == 0) {
 			/* jump to next insn */
 			if (last_line != (unsigned int)adjust->line_no) {
 			    line_info_table[k].line_no = last_line = adjust->line_no;
 			    line_info_table[k].position = pos;
 			    k++;
 			}
 			generated_iseq[pos++] = BIN(jump);
 			generated_iseq[pos++] = 0;
 
 My roundtrip test fails because:
 
 	1. iseq_peephole_optimize called in original
 	2. iseq_set_sequence generates useless jump (above)
 	3. ISeq#to_a called (showing useless jump)
 	4. ISeq#load on 3. array
 	5. iseq_peephole_optimize now deletes jump emitted in 2.
 	6. ISeq#to_a now has no useless jumps
 
 So now I'm trying to figure out how to eliminate the useless jump in 2
 so roundtrip test always succeeds (and my normal Ruby code has
 no useless jump insns)

----------------------------------------
Feature #8543: rb_iseq_load
https://bugs.ruby-lang.org/issues/8543#change-50085

* 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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