[ruby-core:25553] Re: Is this an intentional change in 1.9?

This discussion seems to have died out.  Is this something which
should/will be fixed.  Should I open a bug ticket?

On Thu, Aug 27, 2009 at 12:53 PM, Yusuke ENDOH <[e-mail]> wrote:
> Hi,
>
> 2009/8/27 Rick DeNatale <[e-mail]>:
>> On Wed, Aug 26, 2009 at 7:25 PM, Yukihiro Matsumoto<[e-mail]> wrote:
>>> Hi,
>>>
>>> In message "Re: [ruby-core:25143] Is this an intentional change in 1.9?"
>>> n Thu, 27 Aug 2009 02:30:51 +0900, Rick DeNatale <[e-mail]> writes:
>>>
>>> |This seems like a 1.9 bug. Is it?
>>>
>>> I vaguely remember ko1 explained me about the change due to a YARV
>>> internal issue. e have to wait ko1 to determine it's bug or not.
>>
>> I think it's a code generation issue, and also that it's important not
>> to change the semantics of a.x ||= value
>
>
> I agree.  expected that `a.x ||= value' is equal to `a.x || a.x = value',
> but 1.9 cheated on me.
>
>
>  = Object.new
> ef a.foo; nil; end
> ef a.foo=(x); :boo; end
>
> (a.foo ||= :foo) => :boo
> (a.foo || a.foo = :foo) #=> :foo
>
>
> Here is a patch. hen a.x returns nil or false, three more instructions
> are executed than current implementation.  have not measured actual
> impact of speed.
>
>
> Index: compile.c
> ===================================================================
> --- compile.c (revision 24684)
> +++ compile.c (working copy)
> @@ -3842,22 +3842,26 @@
> f lcfin  r o
> op # r
> val v  r v
> - send a= # v
> - jump lfin # v
> + swap  v r
> + topn 1  v r v
> + send a= # v ?
> + jump lfin # v ?
>
> cfin:  r o
> wap  o r
> +
> + lfin: # o ?
> op # o
>
> - lfin: # v
> -
>  and
> up # r o o
> nless lcfin
> op # r
> val v  r v
> - send a= # v
> - jump lfin # v
> + swap  v r
> + topn 1  v r v
> + send a= # v ?
> + jump lfin # v ?
>
>  others
> val v  r o v
> @@ -3881,15 +3885,17 @@
> 
> DD_INSN(ret, nd_line(node), pop);
> OMPILE(ret, "NODE_OP_ASGN2 val", node->nd_value);
> + ADD_INSN(ret, nd_line(node), swap);
> + ADD_INSN1(ret, nd_line(node), topn, INT2FIX(1));
> DD_SEND(ret, nd_line(node), ID2SYM(node->nd_next->nd_aid),
> INT2FIX(1));
> DD_INSNL(ret, nd_line(node), jump, lfin);
>
> DD_LABEL(ret, lcfin);
> DD_INSN(ret, nd_line(node), swap);
> - ADD_INSN(ret, nd_line(node), pop);
>
> DD_LABEL(ret, lfin);
> + ADD_INSN(ret, nd_line(node), pop);
> 
> lse {
> OMPILE(ret, "NODE_OP_ASGN2 val", node->nd_value);
>
> --
> Yusuke ENDOH <[e-mail]>
>
>



-- 
Rick DeNatale

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