From: Richard Henderson <rth@redhat.com>
To: Richard Kenner <kenner@vlsi1.ultra.nyu.edu>
Cc: dalej@apple.com, gcc@gcc.gnu.org
Subject: Re: Question on insn scheduling and SP
Date: Tue, 22 Oct 2002 12:30:00 -0000 [thread overview]
Message-ID: <20021022181126.GK16329@redhat.com> (raw)
In-Reply-To: <10210221724.AA24996@vlsi1.ultra.nyu.edu>
On Tue, Oct 22, 2002 at 01:24:33PM -0400, Richard Kenner wrote:
> *Two* clobbers are necessary.
>
> (clobber (mem:BLK (scratch)))
> (clobber (mem:BLK stack_pointer_rtx))
>
> The first has the magic form that conflicts with all memory,
> the second contains a reference to the stack pointer. Thus
> the stack pointer adjustment depends on the second clobber,
> the second clobber depends on the first clobber, and the
> first clobber depends on all memory references.
>
> Well if that's what's going on, why not keep it simpler and have the
> first clobber and then
> (use (stack_pointer_rtx))
Because the USE won't conflict with the first clobber.
And if you put them in a PARALLEL, then we're not using
the canonical "bare clobber" that is recognized in a
target-independent manner.
r~
next prev parent reply other threads:[~2002-10-22 18:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-22 11:36 Richard Kenner
2002-10-22 12:30 ` Richard Henderson [this message]
-- strict thread matches above, loose matches on Subject: below --
2002-10-22 8:45 Richard Kenner
2002-10-22 11:25 ` Richard Henderson
2002-10-21 23:15 Richard Kenner
2002-10-22 3:50 ` Richard Henderson
2002-10-21 18:17 Richard Kenner
2002-10-21 18:41 ` Dale Johannesen
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