From: Richard Henderson <rth@twiddle.net>
To: Stefan Weil <sw@weilnetz.de>
Cc: Jay Foad <jay.foad@gmail.com>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] tci: Add implementation of rotl_i64, rotr_i64
Date: Thu, 05 Sep 2013 13:33:50 -0700 [thread overview]
Message-ID: <5228EAAE.1040605@twiddle.net> (raw)
In-Reply-To: <5228E6DF.6090301@weilnetz.de>
On 09/05/2013 01:17 PM, Stefan Weil wrote:
> I added assertions for (t2 > 0) and (t2 < 64). They never raised an abort.
> Are those cases possible? We already have similar code for 32 bit shifts,
> and tcg/optimize.c also includes an implementation which is identical to
> my rotl_i64, rotr_i64.
It is possible, but very rare. In the tcg optimizer, by looking through
constants that the tcg-op.h routines couldn't filter. In the tci backend
by seeing the real data that wasn't constant for the optimizer.
We should handle zero and modulo count rotates in both places.
r~
next prev parent reply other threads:[~2013-09-05 20:34 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-05 12:00 [Qemu-devel] [PATCH] tci: Add implementation of rotl_i64, rotr_i64 Jay Foad
2013-09-05 20:17 ` Stefan Weil
2013-09-05 20:33 ` Richard Henderson [this message]
-- strict thread matches above, loose matches on Subject: below --
2013-09-04 20:49 Stefan Weil
2013-09-04 20:51 ` Stefan Weil
2013-09-09 14:53 ` Aurelien Jarno
2013-09-09 16:14 ` Stefan Weil
2013-09-09 16:47 ` Aurelien Jarno
2013-09-04 23:00 ` Richard Henderson
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