From: Nathan Froyd <froydnj@codesourcery.com>
To: Ian Lance Taylor <iant@google.com>
Cc: roy rosen <roy.1rosen@gmail.com>, gcc@gcc.gnu.org
Subject: Re: lower subreg optimization
Date: Tue, 06 Apr 2010 19:05:00 -0000 [thread overview]
Message-ID: <20100406190541.GM540@codesourcery.com> (raw)
In-Reply-To: <mcr6344qum2.fsf@dhcp-172-17-9-151.mtv.corp.google.com>
On Tue, Apr 06, 2010 at 11:55:01AM -0700, Ian Lance Taylor wrote:
> Nathan Froyd <froydnj@codesourcery.com> writes:
> > Compiling anything that uses doubles on powerpc e500v2 produces awful
> > code due in part to lower-subregs (the register allocator doesn't help,
> > either, but that's a different story).
>
> I doubt that a target hook is required to avoid this. Perhaps
> simple_move_operand should reject a mode changing subreg when the two
> modes are !MODE_TIEABLE_P.
Ah, thanks for the pointer. I'll try poking at that.
> This code is sort of weird, though; why the conversion from DImode to
> DFmode?
Welcome to the wonderful world of e500, which has floating-point
instructions operating on the general purpose registers.
-Nathan
next prev parent reply other threads:[~2010-04-06 19:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-06 9:24 roy rosen
2010-04-06 16:37 ` Jim Wilson
2010-04-08 6:16 ` roy rosen
2010-04-09 16:52 ` Jim Wilson
2010-04-06 16:58 ` Ian Lance Taylor
2010-04-06 17:13 ` Nathan Froyd
2010-04-06 17:27 ` Steven Bosscher
2010-04-06 18:55 ` Ian Lance Taylor
2010-04-06 19:05 ` Nathan Froyd [this message]
2010-04-06 19:23 ` Joseph S. Myers
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