[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 01/10] tcg: Split out swap_commutative as a subr
|
From: |
Richard Henderson |
|
Subject: |
Re: [Qemu-devel] [PATCH 01/10] tcg: Split out swap_commutative as a subroutine |
|
Date: |
Tue, 09 Oct 2012 08:23:27 -0700 |
|
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120911 Thunderbird/15.0.1 |
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~
[Qemu-devel] [PATCH 03/10] tcg: Swap commutative double-word comparisons, Richard Henderson, 2012/10/02
[Qemu-devel] [PATCH 02/10] tcg: Canonicalize add2 operand ordering, Richard Henderson, 2012/10/02
[Qemu-devel] [PATCH 04/10] tcg: Use common code when failing to optimize, Richard Henderson, 2012/10/02