From: Richard Guenther <richard.guenther@gmail.com>
To: Andrew Pinski <pinskia@gmail.com>
Cc: "William J. Schmidt" <wschmidt@linux.vnet.ibm.com>,
Richard Henderson <rth@redhat.com>,
Richard Guenther <rguenther@suse.de>,
gcc-patches@gcc.gnu.org
Subject: Re: [PATCH][RFC][1/2] Bitfield lowering, add BIT_FIELD_EXPR
Date: Mon, 20 Jun 2011 21:03:00 -0000 [thread overview]
Message-ID: <BANLkTik4Sqt+WyWxnv7AWgWr9wqtWTVjTg@mail.gmail.com> (raw)
In-Reply-To: <BANLkTimDvZ4+64zjosVHuAX9DQv3aO8PGA@mail.gmail.com>
On Mon, Jun 20, 2011 at 8:43 PM, Andrew Pinski <pinskia@gmail.com> wrote:
> On Mon, Jun 20, 2011 at 7:19 AM, William J. Schmidt
> <wschmidt@linux.vnet.ibm.com> wrote:
>> On Thu, 2011-06-16 at 09:49 -0700, Richard Henderson wrote:
>>> On 06/16/2011 04:35 AM, Richard Guenther wrote:
>>> >
>>> > + /* Bit-field insertion needs several shift and mask operations. */
>>> > + case BIT_FIELD_EXPR:
>>> > + return 3;
>>>
>>> ... depending on the target, of course.
>>>
>>
>> Agreed -- this is a single-instruction operation on PowerPC. Probably
>> need some target-specific weights here.
>
> It is also a single instruction on MIPS32R2 and MIPS64R2. So a target
> hook is the best here rather than a constant number in the target hook
> field.
Yeah, well. We have mostly no target dependency in those gimple
statement speed/size cost metric, so the above 3 is matching
how the expansion to gimple shift/mask stmts would measure.
Richard.
> Thanks,
> Andrew Pinski
>
next prev parent reply other threads:[~2011-06-20 20:55 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-16 11:46 Richard Guenther
2011-06-16 12:06 ` Jay Foad
2011-06-16 17:18 ` Richard Henderson
2011-06-16 18:10 ` Eric Botcazou
2011-06-16 19:23 ` Richard Guenther
2011-06-16 19:53 ` Richard Henderson
2011-06-20 14:23 ` William J. Schmidt
2011-06-20 19:09 ` Andrew Pinski
2011-06-20 21:03 ` Richard Guenther [this message]
2011-06-20 21:05 ` Andrew Pinski
2011-06-19 23:45 ` William J. Schmidt
2011-06-20 13:44 ` Michael Matz
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