From: Tom Tromey <tom@tromey.com>
To: Tom Tromey <tom@tromey.com>
Cc: emacs-devel@gnu.org
Subject: Re: please review new branch feature/byte-unwind-protect
Date: Tue, 23 Jan 2018 08:50:33 -0700 [thread overview]
Message-ID: <87zi54ing6.fsf@tromey.com> (raw)
In-Reply-To: <m27es9nepu.fsf@newartisans.com> (John Wiegley's message of "Tue, 23 Jan 2018 00:47:57 -0800")
>>>>> "John" == John Wiegley <johnw@gnu.org> writes:
>>>>> "TT" == Tom Tromey <tom@tromey.com> writes:
TT> I recently wrote a couple of patches to add two new bytecodes to Emacs.
TT> These make it possible to compile unwind-protect without the need to
TT> introduce a closure for the unwind forms.
John> Hi Tom,
John> Thanks for these changes. I just want to ask: what motivates them? Is it
John> efficiency? Does it enable something you can't achieve otherwise? If the
John> former, has it been measured? What is the corresponding cost of having this
John> change?
It's partly for efficiency -- I didn't benchmark it though. I suppose I
can. It's pretty normal to see unwind-protect in the expansion of
macros, though; there are plenty in subr.el. This enables better code
generation in the jit I've written (I plan to post about that when it's
ready but I can do it sooner if you want).
Also this seems like an un-finished to-do item from the lexical binding
conversion.
I don't think there's a cost to this change. It uses two byte codes,
but there are still some to spare, so I think it isn't a big deal.
Tom
next prev parent reply other threads:[~2018-01-23 15:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-23 5:20 please review new branch feature/byte-unwind-protect Tom Tromey
2018-01-23 8:47 ` John Wiegley
2018-01-23 15:50 ` Tom Tromey [this message]
2018-01-23 16:37 ` Stefan Monnier
2018-01-27 17:37 ` Markus Triska
2018-01-27 21:28 ` Stefan Monnier
2018-02-03 19:43 ` Philipp Stephani
-- strict thread matches above, loose matches on Subject: below --
2018-01-26 7:58 Rocky Bernstein
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