From: Richard Henderson <rth@twiddle.net>
To: Aurelien Jarno <aurelien@aurel32.net>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 01/10] tcg: Split out swap_commutative as a subroutine
Date: Tue, 09 Oct 2012 08:23:27 -0700 [thread overview]
Message-ID: <5074416F.5010708@twiddle.net> (raw)
In-Reply-To: <20121009151357.GB14078@ohm.aurel32.net>
On 10/09/2012 08:13 AM, Aurelien Jarno wrote:
>> > It also prefers
>> >
>> > add r, r, c
>> > over
>> > add r, c, r
>> >
>> > when both inputs are known constants. This doesn't matter for true add, as
>> > we will fully constant fold that. But it matters for a follow-on patch using
>> > this routine for add2 which may not be fully foldable.
...
> Does this sum += and -= actually generates better code than the previous
> one? It's not something obvious to read (fortunately there is the
> comment for helping), so if it doesn't bring any optimization, it's
> better to keep the previous form.
Yes. See the comment within the log above.
r~
next prev parent reply other threads:[~2012-10-09 15:23 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-02 18:32 [Qemu-devel] [PATCH v2 00/10] Double-word tcg/optimize improvements Richard Henderson
2012-10-02 18:32 ` [Qemu-devel] [PATCH 01/10] tcg: Split out swap_commutative as a subroutine Richard Henderson
2012-10-09 15:13 ` Aurelien Jarno
2012-10-09 15:23 ` Richard Henderson [this message]
2012-10-09 15:31 ` Aurelien Jarno
2012-10-09 16:40 ` Richard Henderson
2012-10-02 18:32 ` [Qemu-devel] [PATCH 02/10] tcg: Canonicalize add2 operand ordering Richard Henderson
2012-10-09 15:14 ` Aurelien Jarno
2012-10-02 18:32 ` [Qemu-devel] [PATCH 03/10] tcg: Swap commutative double-word comparisons Richard Henderson
2012-10-09 15:16 ` Aurelien Jarno
2012-10-09 15:31 ` Richard Henderson
2012-10-09 15:48 ` Aurelien Jarno
2012-10-02 18:32 ` [Qemu-devel] [PATCH 04/10] tcg: Use common code when failing to optimize Richard Henderson
2012-10-09 15:25 ` Aurelien Jarno
2012-10-09 15:33 ` Richard Henderson
2012-10-02 18:32 ` [Qemu-devel] [PATCH 05/10] tcg: Optimize double-word comparisons against zero Richard Henderson
2012-10-09 16:32 ` Aurelien Jarno
2012-10-02 18:32 ` [Qemu-devel] [PATCH 06/10] tcg: Split out subroutines from do_constant_folding_cond Richard Henderson
2012-10-09 16:33 ` Aurelien Jarno
2012-10-02 18:32 ` [Qemu-devel] [PATCH 07/10] tcg: Do constant folding on double-word comparisons Richard Henderson
2012-10-10 9:45 ` Aurelien Jarno
2012-10-02 18:32 ` [Qemu-devel] [PATCH 08/10] tcg: Constant fold add2 and sub2 Richard Henderson
2012-10-10 9:52 ` Aurelien Jarno
2012-10-02 18:32 ` [Qemu-devel] [PATCH 09/10] tcg: Optimize half-dead add2/sub2 Richard Henderson
2012-10-16 23:25 ` Aurelien Jarno
2012-10-02 18:32 ` [Qemu-devel] [PATCH 10/10] tcg: Optimize mulu2 Richard Henderson
2012-10-16 23:25 ` Aurelien Jarno
2012-10-17 1:09 ` Richard Henderson
2012-10-17 10:58 ` Avi Kivity
2012-10-17 16:41 ` [Qemu-devel] [PATCH v2 00/10] Double-word tcg/optimize improvements Aurelien Jarno
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