From: Eric Wong <normalperson@...>
Date: 2015-12-09T09:25:00+00:00
Subject: [ruby-core:71990] Re: [Ruby trunk - Feature #11786] [Open] [PATCH] micro-optimize case dispatch even harder

SASADA Koichi <ko1@atdot.net> wrote:
> On 2015/12/08 13:53, Eric Wong wrote:
> >> > how to mark literal objects?
> > Take ideas from nobu (r52708 :)
> 
> I meant marking, not for freeing a table.
> 
> For example, bignum objects should mark from this table.
> 
> ```ruby
> case nil
> when [bignum literal here]
> end
> ```
> 
> (Sorry if I overlooked marking)

Wait, putobject calls (and TS_VALUE operands) do not go away when
opt_case_dispatch insn is emitted, so marking keys in literal hash is
redundant. since iseq_set_sequence adds marks for all TS_VALUE.
(but maybe I'm misreading compile.c, too)

> I'm not sure it is worth or not. IMO keeping simple with Hash is better
> on this case with your measured improvements.

Yes, we can revisit after 2.3 release.  Maybe this is appropriate for
sorted array + bsearch since the table is frozen at compile time and
st uses too much memory.