From: Benoit Daloze <eregontp@...>
Date: 2010-08-13T07:11:06+09:00
Subject: Re: Tail recursion with 1.9

On 12 August 2010 23:52, Iain Barnett <iainspeed@gmail.com> wrote:
>
>
>
> On 10 Aug 2010, at 16:43, Joseph E. Savard wrote:
>
>> Its commented out.
>>
>> See vm_opts.h.
>>
>> As far as sensing it in Ruby I would think
>>
>> ruby-1.9.2-rc2.tar.bz2>
>>
>> Snippet of vm_opts.h below:
>>
>> #ifndef RUBY_VM_OPTS_H
>> #define RUBY_VM_OPTS_H
>>
>> /* Compile options.
>> * You can change these options at runtime by VM::CompileOption.
>> * Following definitions are default values.
>> */
>>
>> #define OPT_TRACE_INSTRUCTION        1
>> #define OPT_TAILCALL_OPTIMIZATION    0
>> #define OPT_PEEPHOLE_OPTIMIZATION    1
>> #define OPT_SPECIALISED_INSTRUCTION  1
>> #define OPT_INLINE_CONST_CACHE       1
>>
>> RUN TIME OPTIONS could be interesting to play with.  You appear to loose the
>> promise of portability.
>>
>> See iseq.c (Interesting rb_compile_option_t )
>>
>> static rb_compile_option_t COMPILE_OPTION_DEFAULT = {
>>    OPT_INLINE_CONST_CACHE, /* int inline_const_cache; */
>>    OPT_PEEPHOLE_OPTIMIZATION, /* int peephole_optimization; */
>>    OPT_TAILCALL_OPTIMIZATION, /* int tailcall_optimization */
>>    OPT_SPECIALISED_INSTRUCTION, /* int specialized_instruction; */
>>    OPT_OPERANDS_UNIFICATION, /* int operands_unification; */
>>    OPT_INSTRUCTIONS_UNIFICATION, /* int instructions_unification; */
>>    OPT_STACK_CACHING, /* int stack_caching; */
>>    OPT_TRACE_INSTRUCTION, /* int trace_instruction */
>> };
>>
>
> Thanks for the reply. Finally got 1.9.1-p429 to compile, and I set  #define OPT_TAILCALL_OPTIMIZATION   1  before compiling, which hopefully is right, I don't know C.
>
> Do you know any way I can check it's definitely on, aside from attempting to blow the stack with something hugely recursive?
>
> Iain
>

You should probably dig deeper in your own link :)

There is a link on the stackoverflow's question:
http://redmine.ruby-lang.org/issues/show/1256
The third reply from Nobu might help you ;)

Regards,
B.D.