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From: Jim Wilson <jimw@sifive.com>
To: Michael Meissner <meissner@linux.ibm.com>,
	GCC Patches <gcc-patches@gcc.gnu.org>,
	 Segher Boessenkool <segher@kernel.crashing.org>,
	David Edelsohn <dje.gcc@gmail.com>,
	 Bill Schmidt <wschmidt@linux.ibm.com>,
	Peter Bergner <bergner@linux.ibm.com>,
	 Will Schmidt <will_schmidt@vnet.ibm.com>
Subject: Re: [PATCH] Fix SFmode subreg of DImode and TImode
Date: Thu, 9 Sep 2021 14:59:14 -0700	[thread overview]
Message-ID: <CAFyWVaZebx+5NMW28s8Z77h1b9LTvhP1bVPpw04nZonaN2P4yw@mail.gmail.com> (raw)
In-Reply-To: <YTcQ5BZr4NQvH7DY@toto.the-meissners.org>

On Tue, Sep 7, 2021 at 12:12 AM Michael Meissner via Gcc-patches <
gcc-patches@gcc.gnu.org> wrote:

> This patch fixes the breakage in the PowerPC due to a recent change in
> SUBREG
> behavior.  While it is arguable that the patch that caused the breakage
> should
> be reverted, this patch should be a bandage to prevent these changes from
> happening again.
>

FYI I'm dealing with the same problem in the RISC-V backend via
    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102211

My current proposed solution is a new predicate f_register_operand to be
used in patterns that use the f constraint which disallows the subregs that
can't work in FP registers due to NaN-boxing.  This just borrows a few
lines of code that were deleted from validate_subreg and puts it in a
RISC-V specific predicate function.  It worked for newlib and glibc
builds.  I'm trying bootstrap testing now, but my target is a little slower
than yours so this will take some time.

Jim

      parent reply	other threads:[~2021-09-09 21:59 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-07  7:12 Michael Meissner
2021-09-07 23:07 ` Segher Boessenkool
2021-09-08  6:42   ` Richard Biener
2021-09-08 17:08     ` Segher Boessenkool
2021-09-08 17:50       ` David Edelsohn
2021-09-08 18:39       ` Richard Biener
2021-09-08 19:16         ` Segher Boessenkool
2021-09-09  1:23           ` Hongtao Liu
2021-09-09  1:31           ` Hongtao Liu
2021-09-09  6:16           ` Richard Biener
2021-09-09 22:53             ` Michael Meissner
2021-09-09 23:48             ` Segher Boessenkool
2021-09-10  3:09               ` Hongtao Liu
2021-09-10 10:54                 ` Richard Biener
2021-09-10 11:25                   ` Hongtao Liu
2021-09-10 12:34                     ` Hongtao Liu
2021-09-10 14:08                 ` David Edelsohn
2021-09-10 14:14                   ` Hongtao Liu
2021-09-10 15:32                 ` Segher Boessenkool
2021-09-10 10:53               ` Richard Biener
2021-09-10 15:05                 ` Segher Boessenkool
2021-09-13  9:03                   ` Richard Biener
2021-09-08 15:31   ` Michael Meissner
2021-09-09 21:59 ` Jim Wilson [this message]

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