From: nagachika00@...
Date: 2016-11-11T15:35:36+00:00
Subject: [ruby-core:78085] [Ruby trunk Bug#12905] tailcall_optimization not working as expected under certain condition order

Issue #12905 has been updated by Tomoyuki Chikanaga.

Backport changed from 2.1: REQUIRED, 2.2: REQUIRED, 2.3: REQUIRED to 2.1: REQUIRED, 2.2: REQUIRED, 2.3: DONE

ruby_2_3 r56715 merged revision(s) 56208,56663.

----------------------------------------
Bug #12905: tailcall_optimization not working as expected under certain condition order
https://bugs.ruby-lang.org/issues/12905#change-61436

* Author: Kai Sun
* Status: Closed
* Priority: Normal
* Assignee: 
* ruby -v: 2.3.1
* Backport: 2.1: REQUIRED, 2.2: REQUIRED, 2.3: DONE
----------------------------------------
Below code gets stack too deep error:

~~~ ruby
RubyVM::InstructionSequence.compile_option = {
  :tailcall_optimization => true,
  :trace_instruction => false
}

def run_forever(current, final)
  if current < final
    run_forever(current+1, final)
  else
    nil
  end
end

run_forever(1, Float::INFINITY)
~~~

However, below code works as expected:

~~~ ruby
RubyVM::InstructionSequence.compile_option = {
  :tailcall_optimization => true,
  :trace_instruction => false
}

def run_forever(current, final)
  if current >= final
    nil
  else
    run_forever(current+1, final)
  end
end

run_forever(1, Float::INFINITY)
~~~

Thanks for looking at this :)



-- 
https://bugs.ruby-lang.org/

Unsubscribe: <mailto:ruby-core-request@ruby-lang.org?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>