From: "Ulrich Weigand" <uweigand@de.ibm.com>
To: ubizjak@gmail.com (Uros Bizjak)
Cc: gcc-patches@gcc.gnu.org, gcc@gcc.gnu.org (GCC Development),
hjl.tools@gmail.com (H.J. Lu)
Subject: Re: [RFC PATCH, i386]: Allow zero_extended addresses (+ problems with reload and offsetable address, "o" constraint)
Date: Mon, 08 Aug 2011 15:30:00 -0000 [thread overview]
Message-ID: <201108081530.p78FUAgM029764@d06av02.portsmouth.uk.ibm.com> (raw)
In-Reply-To: <CAFULd4byLVikq6tTudXVUpqLvaC6vTsM3Kd=1eT0fTka=ZOKgg@mail.gmail.com> from "Uros Bizjak" at Aug 07, 2011 02:38:49 PM
Uros Bizjak wrote:
> Although, it would be nice for reload to subsequently fix CSE'd
> non-offsetable memory by copying address to temporary reg (*as said in
> the documentation*), we could simply require an XMM temporary for
> TImode reloads to/from integer registers, and this fixes ICE for x32.
Moves are special as far as reload is concerned. If there is already
a move instruction present *before* reload, it will get fixed up
according to its constraints as any other instruction.
However, reload will *introduce* new moves as part of its operation,
and those will *not* themselves get reloaded. Instead, reload simply
assumes that every plain move will just succeed without requiring
any reload; if this is not true, the target *must* provide a
secondary reload for this move.
(Note that the secondary reload could also work by reloading the
target address into a temporary; that's up to the target to
implement.)
Bye,
Ulrich
--
Dr. Ulrich Weigand
GNU Toolchain for Linux on System z and Cell BE
Ulrich.Weigand@de.ibm.com
next prev parent reply other threads:[~2011-08-08 15:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-05 18:51 Uros Bizjak
2011-08-07 12:39 ` Uros Bizjak
2011-08-08 15:30 ` Ulrich Weigand [this message]
2011-08-08 17:12 ` Uros Bizjak
2011-08-08 17:14 ` H.J. Lu
2011-08-09 7:41 ` Uros Bizjak
2011-08-09 15:40 ` H.J. Lu
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