From: Richard Henderson <rth@twiddle.net>
To: Blue Swirl <blauwirbel@gmail.com>
Cc: mj.mccormack@samsung.com, qemu-devel@nongnu.org, zhur@ispras.ru,
Kirill Batuzov <batuzovk@ispras.ru>
Subject: Re: [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations.
Date: Thu, 26 May 2011 14:14:05 -0700 [thread overview]
Message-ID: <4DDEC29D.6020204@twiddle.net> (raw)
In-Reply-To: <BANLkTinZxVg+pAFAJ0KsCFRG9zoTzyoaKg@mail.gmail.com>
On 05/26/2011 01:25 PM, Blue Swirl wrote:
>> I don't see the point. The C99 implementation defined escape hatch
>> exists for weird cpus. Which we won't be supporting as a QEMU host.
>
> Maybe not, but a compiler with this property could arrive. For
> example, GCC developers could decide that since this weirdness is
> allowed by the standard, it may be implemented as well.
If you like, you can write a configure test for it. But, honestly,
essentially every place in qemu that uses shifts on signed types
would have to be audited. Really.
The C99 hook exists to efficiently support targets that don't have
arithmetic shift operations. Honestly.
r~
next prev parent reply other threads:[~2011-05-26 21:14 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-20 12:39 [Qemu-devel] [PATCH 0/6] Implement constant folding and copy propagation in TCG Kirill Batuzov
2011-05-20 12:39 ` [Qemu-devel] [PATCH 1/6] Add TCG optimizations stub Kirill Batuzov
2011-05-20 18:12 ` Richard Henderson
2011-05-20 18:33 ` Richard Henderson
2011-05-20 12:39 ` [Qemu-devel] [PATCH 2/6] Add copy and constant propagation Kirill Batuzov
2011-05-20 18:22 ` Richard Henderson
2011-05-20 18:46 ` Paolo Bonzini
2011-05-20 19:41 ` Aurelien Jarno
2011-05-20 12:39 ` [Qemu-devel] [PATCH 3/6] Do constant folding for basic arithmetic operations Kirill Batuzov
2011-05-20 12:39 ` [Qemu-devel] [PATCH 4/6] Do constant folding for boolean operations Kirill Batuzov
2011-05-20 18:45 ` Richard Henderson
2011-05-20 12:39 ` [Qemu-devel] [PATCH 5/6] Do constant folding for shift operations Kirill Batuzov
2011-05-20 18:37 ` Richard Henderson
2011-05-26 12:36 ` Kirill Batuzov
2011-05-26 13:56 ` Richard Henderson
2011-05-26 19:14 ` Blue Swirl
2011-05-26 20:10 ` Richard Henderson
2011-05-26 20:25 ` Blue Swirl
2011-05-26 21:14 ` Richard Henderson [this message]
2011-05-27 15:41 ` Jamie Lokier
2011-05-27 17:07 ` Blue Swirl
2011-05-27 19:54 ` Richard Henderson
2011-05-27 7:09 ` Paolo Bonzini
2011-05-20 12:39 ` [Qemu-devel] [PATCH 6/6] Do constant folding for unary operations Kirill Batuzov
2011-05-20 18:39 ` Richard Henderson
2011-05-20 17:50 ` [Qemu-devel] [PATCH 0/6] Implement constant folding and copy propagation in TCG Richard Henderson
2011-05-20 19:37 ` Aurelien Jarno
2011-05-20 23:31 ` Andreas Färber
2011-05-21 9:37 ` Laurent Desnogues
2011-05-21 10:46 ` Aurelien Jarno
2011-05-21 17:53 ` Kirill Batuzov
2011-05-20 19:35 ` Aurelien Jarno
2011-05-21 12:47 ` Dmitry Zhurikhin
2011-05-21 12:48 ` Aurelien Jarno
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