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From: Hans-Peter Nilsson <hp@bitrange.com>
To: Richard Earnshaw <rearnsha@arm.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [patch][ARM] Fix 16-bit -> 64-bit multiply and accumulate
Date: Wed, 09 Feb 2011 06:31:00 -0000	[thread overview]
Message-ID: <alpine.BSF.2.00.1102090114520.65587@dair.pair.com> (raw)
In-Reply-To: <1296223929.9738.30.camel@e102346-lin.cambridge.arm.com>

On Fri, 28 Jan 2011, Richard Earnshaw wrote:
> Canonical RTL is not just about the order of the operands its about not
> having multiple ways of representing the same operation.  Order is part
> of that, but not the end of it.  For example, the canonical form of
>
> 	(lt:SI (reg:SI) (const_int 0))
>
> is
> 	(lshiftrt:SI (reg:SI) (const_int 31))

I kind of doubt that's canon.  At least it shouldn't be that
way, except as a variant attempted by combine.

If so, ISTM i'd be a complicating factor for the cmpM patterns
of most ports. :)  (Likewise unnamed variants for combine.)

brgds, H-P

      parent reply	other threads:[~2011-02-09  6:31 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-09 16:45 Andrew Stubbs
2011-01-27  2:09 ` Ramana Radhakrishnan
2011-01-27 10:46   ` Andrew Stubbs
2011-01-27 19:22 ` Richard Earnshaw
2011-01-28 13:06   ` Andrew Stubbs
2011-01-28 15:08     ` Richard Earnshaw
2011-01-28 15:55       ` Andrew Stubbs
2011-01-28 16:01         ` Richard Earnshaw
2011-03-25 16:27           ` Andrew Stubbs
2011-04-15 11:23             ` Andrew Stubbs
2011-05-03  9:08               ` Bernd Schmidt
2011-05-03  9:36                 ` Andrew Stubbs
2011-05-18 15:32                 ` [patch][combine] " Andrew Stubbs
2011-05-19 13:06                   ` Bernd Schmidt
2011-05-24 17:51                 ` [patch][simplify-rtx] " Andrew Stubbs
2011-05-24 21:00                   ` Joseph S. Myers
2011-05-25  9:47                     ` Andrew Stubbs
2011-05-25 12:34                       ` Joseph S. Myers
2011-05-25 13:42                     ` Andrew Stubbs
2011-05-25 13:48                       ` Joseph S. Myers
2011-05-25 14:01                         ` Andrew Stubbs
2011-05-25 14:27                           ` Joseph S. Myers
2011-05-26 13:57                             ` Andrew Stubbs
2011-05-26 14:47                               ` Joseph S. Myers
2011-06-02  9:46                               ` Richard Earnshaw
2011-06-07 11:05                                 ` Andrew Stubbs
2011-02-09  6:31       ` Hans-Peter Nilsson [this message]

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