From: erik quanstrom <quanstro@quanstro.net>
To: 9fans@9fans.net
Subject: Re: [9fans] extern register
Date: Fri, 18 Jul 2014 22:41:18 -0400 [thread overview]
Message-ID: <6d311463eb8d91270a6fc9ddf33d7d92@ladd.quanstro.net> (raw)
In-Reply-To: <299507dd57a667108bf5d8986778b430@felloff.net>
On Fri Jul 18 22:28:12 EDT 2014, cinap_lenrek@felloff.net wrote:
> so, we say r14 and r15 arent really special for user programs. and its
> just a c compiler implementation detail that it doesnt allocate these
> registers, but assembly code can freely use them for scratch space
> or whatever. extern register will not work in userspace c programs
> because syscalls will trash these registers.
>
> makes any sense?
certainly.
speaking for myself, the model that r14 and r15 are off limits for
esoteric reasons is preferrable, given the quite limited maximum
benefit, to the complications of sneaking by the limitation.
obviously, the mips port avoided this by never needing >28 live
registers at once.
- erik
next prev parent reply other threads:[~2014-07-19 2:41 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-19 1:57 cinap_lenrek
2014-07-19 2:04 ` erik quanstrom
2014-07-19 2:19 ` erik quanstrom
2014-07-19 2:33 ` cinap_lenrek
2014-07-19 2:37 ` erik quanstrom
2014-07-19 2:27 ` cinap_lenrek
2014-07-19 2:41 ` erik quanstrom [this message]
2014-07-19 12:29 ` Aram Hăvărneanu
2014-07-19 12:42 ` Charles Forsyth
2014-07-19 14:38 ` Aram Hăvărneanu
2014-07-19 14:55 ` erik quanstrom
2014-07-19 15:53 ` Aram Hăvărneanu
2014-07-20 1:42 ` cinap_lenrek
2014-07-20 10:12 ` Aram Hăvărneanu
2014-07-20 16:35 ` cinap_lenrek
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