From: "garysweaver (Gary Weaver)" <garysweaver@...>
Date: 2013-11-28T07:43:19+09:00
Subject: [ruby-core:58648] [ruby-trunk - Bug #9114]	InstructionSequence.compile w/tailcall_optimization: true,	trace_instruction: false not working as expected


Issue #9114 has been updated by garysweaver (Gary Weaver).


Eric,

My apologizes as I probably wasted your time with that. The problem with the code you posted is that for TCO you still have to specify trace_instruction: false. If you execute the following, it is fine in Ruby 2.0.0 at least, unless it doesn't work in trunk/master:

source = <<-SOURCE
def fact n, acc = 1
  if n.zero?
    acc
  else
    fact n - 1, acc * n
  end
end

fact 10000
SOURCE

i_seq = RubyVM::InstructionSequence.new source, nil, nil, nil,
  tailcall_optimization: true, trace_instruction: false

puts i_seq.disasm

begin
  value = i_seq.eval

  p value
rescue SystemStackError => e
  puts e
end


---

I wasn't doing a tail call, which was my problem I think :( , so can close.
----------------------------------------
Bug #9114: InstructionSequence.compile w/tailcall_optimization: true, trace_instruction: false not working as expected
https://bugs.ruby-lang.org/issues/9114#change-43216

Author: garysweaver (Gary Weaver)
Status: Assigned
Priority: Normal
Assignee: ko1 (Koichi Sasada)
Category: 
Target version: 
ruby -v: ruby 2.0.0p247 (2013-06-27 revision 41674) [x86_64-darwin11.4.2]
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


Code to reproduce is a recursive sort I wrote; I was trying to compile RubyVM::InstructionSequence with tailcall_optimization: true, trace_instruction: false, which has worked before, but not for this case. 

method_string = <<RUBY
def recursively_sort(obj, in_sort_by=false)
 if obj.respond_to?(:sort_by)
   obj.sort_by{|*args|args.map{|v|recursively_sort(v, true)}}
 end rescue nil
 in_sort_by ? (obj.to_s rescue obj.inspect rescue nil) : obj
end
RUBY

RubyVM::InstructionSequence.new(method_string, nil, nil, nil, tailcall_optimization: true, trace_instruction: false).eval

a = eval '[{b:['*1000 + '2,1' + '],a:1}]'*1000

recursively_sort a

results in error for latest releases of Ruby 1.9.3 and 2.0.0:

1.9.3-p448 :014 >   recursively_sort a
SystemStackError: stack level too deep
	from /Users/gary/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/irb/workspace.rb:80
Maybe IRB bug!

2.0.0p247 :014 >   recursively_sort a
SystemStackError: stack level too deep
	from /Users/gary/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/irb/workspace.rb:86
Maybe IRB bug!

I had assumed that since the blocks were defined within the tail call optimized method that referenced the method compiled with TCO, it would still be tail call optimized.

Did I do something wrong/is there a suggested workaround?

Thanks for looking at this!


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