From: Kyrill Tkachov <kyrylo.tkachov@arm.com>
To: GCC Patches <gcc-patches@gcc.gnu.org>
Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>,
Richard Earnshaw <Richard.Earnshaw@arm.com>
Subject: Re: [PATCH][ARM] PR target/67929 Tighten vfp3_const_double_for_bits checks
Date: Mon, 26 Oct 2015 12:17:00 -0000 [thread overview]
Message-ID: <562E199F.3090801@arm.com> (raw)
In-Reply-To: <561E4941.6030204@arm.com>
Ping.
https://gcc.gnu.org/ml/gcc-patches/2015-10/msg01350.html
and the backport for 4.9/5
https://gcc.gnu.org/ml/gcc-patches/2015-10/msg01351.html
Thanks,
Kyrill
On 14/10/15 13:23, Kyrill Tkachov wrote:
> Hi all,
>
> This patch fixes the referenced PR by rewriting the vfp3_const_double_for_bits function in arm.c
> The function is supposed to accept positive CONST_DOUBLE rtxes whose value is an exact power of 2
> and whose log2 is between 1 and 32. That is values like 2.0, 4.0, 8.9, 16.0 etc...
>
> The current implementation seems to have been written under the assumption that exact_real_truncate returns
> false if the input value is not an exact integer, whereas in fact exact_real_truncate returns false if the
> truncation operation was not exact, which are different things. This would lead the function to accept any
> CONST_DOUBLE that can truncate to a power of 2, such as 4.9, 16.2 etc.
>
> In any case, I've rewritten this function and used the real_isinteger predicate to check if the real value
> is an exact integer.
>
> The testcase demonstrates the kind of wrong code that this patch addresses.
>
> This bug appears on GCC 5 and 4.9 as well, but due to the recent introduction of CONST_DOUBLE_REAL_VALUE
> this patch doesn't apply on those branches. I will soon post the backportable variant.
>
> Bootstrapped and tested on arm-none-linux-gnueabihf.
>
> Ok for trunk?
>
> Thanks,
> Kyrill
>
> 2015-10-12 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
>
> PR target/67929
> * config/arm/arm.c (vfp3_const_double_for_bits): Rewrite.
> * config/arm/constraints.md (Dp): Update callsite.
> * config/arm/predicates.md (const_double_vcvt_power_of_two): Likewise.
>
> 2015-10-12 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
>
> PR target/67929
> * gcc.target/arm/pr67929_1.c: New test.
next prev parent reply other threads:[~2015-10-26 12:16 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-14 12:23 Kyrill Tkachov
2015-10-26 12:17 ` Kyrill Tkachov [this message]
2015-10-27 12:25 ` Ramana Radhakrishnan
2015-11-01 19:22 ` Yvan Roux
2015-11-02 8:38 ` Ramana Radhakrishnan
2015-11-02 8:51 ` Yvan Roux
2015-11-02 9:02 ` Christophe Lyon
2015-11-02 9:24 ` Ramana Radhakrishnan
2015-11-02 9:28 ` Yvan Roux
2015-11-02 9:30 ` Kyrill Tkachov
2015-11-02 11:36 ` Kyrill Tkachov
2015-11-02 11:51 ` Richard Earnshaw
2015-11-02 9:20 ` Kyrill Tkachov
2015-11-02 9:26 ` Ramana Radhakrishnan
2015-11-02 11:24 ` Richard Earnshaw
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=562E199F.3090801@arm.com \
--to=kyrylo.tkachov@arm.com \
--cc=Richard.Earnshaw@arm.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=ramana.radhakrishnan@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).