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From: Nicholas Piggin <npiggin@gmail.com>
To: Rich Felker <dalias@libc.org>
Cc: Adhemerval Zanella <adhemerval.zanella@linaro.org>,
	libc-alpha@sourceware.org, libc-dev@lists.llvm.org,
	linuxppc-dev@lists.ozlabs.org, musl@lists.openwall.com
Subject: Re: [musl] Powerpc Linux 'scv' system call ABI proposal take 2
Date: Wed, 22 Apr 2020 16:29:19 +1000	[thread overview]
Message-ID: <1587536847.k87ypbo53k.astroid@bobo.none> (raw)
In-Reply-To: <1587531042.1qvc287tsc.astroid@bobo.none>

Excerpts from Nicholas Piggin's message of April 22, 2020 4:18 pm:
> If we go further and try to preserve r3 as well by putting the return 
> value in r9 or r0, we go backwards about 300 bytes. It's good for the 
> lock loops and complex functions, but hurts a lot of simpler functions 
> that have to add 'mr r3,r9' etc.  
> 
> Most of the time there are saved non-volatile GPRs around anyway though, 
> so not sure which way to go on this. Text size savings can't be ignored
> and it's pretty easy for the kernel to do (we already save r3-r8 and
> zero them on exit, so we could load them instead from cache line that's
> should be hot).
> 
> So I may be inclined to go this way, even if we won't see benefit now.

By, "this way" I don't mean r9 or r0 return value (which is larger code),
but r3 return value with r0,r4-r8 preserved.

Thanks,
Nick

  reply	other threads:[~2020-04-22  6:32 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-15 21:45 Nicholas Piggin
2020-04-15 22:55 ` Rich Felker
2020-04-16  0:16   ` Nicholas Piggin
2020-04-16  0:48     ` Rich Felker
2020-04-16  2:24       ` Nicholas Piggin
2020-04-16  2:35         ` Rich Felker
2020-04-16  2:53           ` Nicholas Piggin
2020-04-16  3:03             ` Rich Felker
2020-04-16  3:41               ` Nicholas Piggin
2020-04-16 20:18             ` Florian Weimer
2020-04-16  9:58     ` Szabolcs Nagy
2020-04-20  0:27       ` Nicholas Piggin
2020-04-20  1:29         ` Rich Felker
2020-04-20  2:08           ` Nicholas Piggin
2020-04-20 21:17             ` Szabolcs Nagy
2020-04-21  9:57               ` Florian Weimer
2020-04-16 15:21     ` Jeffrey Walton
2020-04-16 15:40       ` Rich Felker
2020-04-16  4:48   ` Florian Weimer
2020-04-16 15:35     ` Rich Felker
2020-04-16 16:42       ` Florian Weimer
2020-04-16 16:52         ` Rich Felker
2020-04-16 18:12           ` Florian Weimer
2020-04-16 23:02             ` Segher Boessenkool
2020-04-17  0:34               ` Rich Felker
2020-04-17  1:48                 ` Segher Boessenkool
2020-04-17  8:34                   ` Florian Weimer
2020-04-16 14:16   ` Adhemerval Zanella
2020-04-16 15:37     ` Rich Felker
2020-04-16 17:50       ` Adhemerval Zanella
2020-04-16 17:59         ` Rich Felker
2020-04-16 18:18           ` Adhemerval Zanella
2020-04-16 18:31             ` Rich Felker
2020-04-16 18:44               ` Rich Felker
2020-04-16 18:52               ` Adhemerval Zanella
2020-04-20  0:46                 ` Nicholas Piggin
2020-04-20  1:10               ` Nicholas Piggin
2020-04-20  1:34                 ` Rich Felker
2020-04-20  2:32                   ` Nicholas Piggin
2020-04-20  4:09                     ` Rich Felker
2020-04-20  4:31                       ` Nicholas Piggin
2020-04-20 17:27                         ` Rich Felker
2020-04-22  6:18                           ` Nicholas Piggin
2020-04-22  6:29                             ` Nicholas Piggin [this message]
2020-04-23  2:36                             ` Rich Felker
2020-04-23 12:13                               ` Adhemerval Zanella
2020-04-23 16:18                                 ` Rich Felker
2020-04-23 16:35                                   ` Adhemerval Zanella
2020-04-23 16:43                                     ` Rich Felker
2020-04-23 17:15                                       ` Adhemerval Zanella
2020-04-23 17:42                                         ` Rich Felker
2020-04-25  3:40                                           ` Nicholas Piggin
2020-04-25  4:52                                             ` Rich Felker
2020-04-25  3:30                               ` Nicholas Piggin
2020-04-21 12:28                 ` David Laight
2020-04-21 14:39                   ` Rich Felker
2020-04-21 15:00                     ` Adhemerval Zanella
2020-04-21 15:31                       ` David Laight
2020-04-22  6:54                       ` [musl] " Nicholas Piggin
2020-04-22  7:15                         ` Florian Weimer
2020-04-22  7:31                           ` Nicholas Piggin
2020-04-22  8:11                             ` Florian Weimer

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