From: Nigel Stephens <nigel@mips.com>
To: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: Richard Sandiford <rsandifo@redhat.com>,
Ralf Baechle <ralf@linux-mips.org>,
Richard Henderson <rth@redhat.com>,
gcc-patches@gcc.gnu.org, linux-mips@linux-mips.org
Subject: Re: [patch] MIPS/gcc: Revert removal of DImode shifts for 32-bit targets
Date: Wed, 04 Aug 2004 21:37:04 +0100 [thread overview]
Message-ID: <411148F0.2040605@mips.com> (raw)
In-Reply-To: <Pine.LNX.4.58L.0408042123030.31930@blysk.ds.pg.gda.pl>
Maciej W. Rozycki wrote:
> Here are my proposals I've referred to previously. Instruction counts
>are 9, 9 and 10, respectively, as I've missed an additional instruction
>required to handle shifts by 0 (or actually any multiples of 64).
>
IMHO handling a shift by zero correctly is important.
> "not %1, %3\n\t"
> "srlv %1, %L2, %1\n\t"
> "srl %1, %1, 1\n\t"
>
Why not the shorter:
> "neg %1, %3\n\t"
> "srlv %1, %L2, %1\n\t"
>
>
>
And then in __ashrdi3:
"andi %1, %3, 0x20\n\t"
".set push\n\t"
".set noat\n\t"
"sra $1, %M2, 31\n\t"
"movn %L0, %M0, %1\n\t"
"movn %M0, $1, %1\n\t"
".set pop"
Cute, but I think that should be
"sra $1, %M0, 31\n\t"
(i.e %M0 not %M2)
Nigel
next prev parent reply other threads:[~2004-08-04 20:37 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-07-19 15:35 [patch] MIPS/gcc: Revert removal of DImode shifts for 32-bit targets Maciej W. Rozycki
2004-07-19 16:59 ` Richard Sandiford
2004-07-19 17:32 ` [patch] MIPS/gcc: Revert removal of DImode shifts for 32-bittargets David Edelsohn
2004-07-19 17:33 ` [patch] MIPS/gcc: Revert removal of DImode shifts for 32-bit targets Maciej W. Rozycki
2004-07-19 17:37 ` Richard Sandiford
2004-07-19 21:38 ` Richard Henderson
2004-07-23 14:41 ` Maciej W. Rozycki
2004-07-23 20:27 ` Richard Henderson
2004-07-23 21:12 ` Ralf Baechle
2004-07-26 11:56 ` Maciej W. Rozycki
2004-08-02 20:03 ` Nigel Stephens
2004-08-03 5:30 ` Richard Sandiford
2004-08-03 9:22 ` Nigel Stephens
2004-08-03 9:36 ` Richard Sandiford
2004-08-03 9:54 ` Nigel Stephens
2004-08-04 19:57 ` Maciej W. Rozycki
2004-08-04 20:37 ` Nigel Stephens [this message]
2004-08-04 20:54 ` Maciej W. Rozycki
2004-08-04 23:39 ` Nigel Stephens
2004-08-07 19:01 ` Richard Sandiford
2004-08-09 22:08 ` Richard Henderson
2004-08-10 5:30 ` Richard Sandiford
2004-08-10 23:20 ` Richard Henderson
2004-08-11 0:24 ` Andreas Schwab
2004-08-11 0:40 ` Paul Brook
2004-08-11 4:32 ` Richard Henderson
2004-08-31 19:51 ` Richard Sandiford
2004-09-03 6:53 ` Richard Henderson
2004-09-03 7:05 ` Richard Sandiford
2004-09-03 7:08 ` Richard Henderson
2004-09-03 7:11 ` Richard Sandiford
2004-09-03 7:20 ` Richard Henderson
2004-09-03 7:29 ` Richard Sandiford
2004-09-03 20:15 ` Richard Henderson
2004-09-04 8:53 ` Richard Sandiford
2004-09-05 0:03 ` Richard Henderson
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