From: "H.J. Lu" <hjl.tools@gmail.com>
To: Jakub Jelinek <jakub@redhat.com>
Cc: Uros Bizjak <ubizjak@gmail.com>,
Ilya Enkovich <enkovich.gnu@gmail.com>,
GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH, PR target/69454] Disable TARGET_STV when stack is not properly aligned
Date: Tue, 02 Feb 2016 12:30:00 -0000 [thread overview]
Message-ID: <CAMe9rOr4z3W6k=GrecTQPTJcdD_yZd4=9jA5R=768rS1NTuxcw@mail.gmail.com> (raw)
In-Reply-To: <20160202122922.GQ3017@tucnak.redhat.com>
On Tue, Feb 2, 2016 at 4:29 AM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Tue, Feb 02, 2016 at 01:24:26PM +0100, Uros Bizjak wrote:
>> On Tue, Feb 2, 2016 at 12:53 PM, Jakub Jelinek <jakub@redhat.com> wrote:
>>
>> >> The bottom line is ix86_minimum_alignment must return the correct
>> >> number for DImode or you can just turn off STV. My suggestion is
>> >> to use my patch.
>> >
>> > Uros, any preferences here? I mean, it is possible to use
>> > e.g. the ix86_option_override_internal and have H.J's ix86_minimum_alignment
>> > change as a safety net, in the usual case for -mpreferred-stack-boundary=2
>> > we'll just disable TARGET_STV and ix86_minimum_alignment change won't do
>> > anything, as TARGET_STV will be false, and if for whatever case it gets
>> > through (target attribute, -mincoming-stack-boundary=, ...)
>> > ix86_minimum_alignment will be there to ensure enough stack alignment.
>> > Most of the smaller -mpreferred-stack-boundary= uses are -mno-sse anyway,
>> > and that is something we don't want to affect.
>>
>> IMO, we should disable STV when -mpreferred-stack-boundary < 3, as STV
>> is only an optimization. Perhaps we can also emit a "sorry" for
>> explicit -mstv in case stack boundary requirement is not satisfied.
>> *If* there is a need for -mstv with smaller stack boundary, we can
>> revisit this decision for later gcc versions.
>>
>> I think disabling STV is less surprising option than increasing stack
>> boundary behind the user's back.
>
> So, is http://gcc.gnu.org/ml/gcc-patches/2016-01/msg02129.html
> ok for trunk then (alone or with additional sorry, incremental or not?)?
> I believe it does just that.
This patch is WRONG.
--
H.J.
next prev parent reply other threads:[~2016-02-02 12:30 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-27 15:35 Ilya Enkovich
2016-01-27 15:43 ` H.J. Lu
2016-01-27 16:09 ` Ilya Enkovich
2016-01-27 15:44 ` Jakub Jelinek
2016-01-27 16:12 ` Ilya Enkovich
2016-01-27 16:18 ` H.J. Lu
2016-01-27 16:29 ` Ilya Enkovich
2016-01-27 16:36 ` H.J. Lu
2016-01-28 6:00 ` H.J. Lu
2016-01-28 10:06 ` Ilya Enkovich
2016-01-28 12:42 ` H.J. Lu
2016-02-02 11:53 ` Jakub Jelinek
2016-02-02 12:24 ` Uros Bizjak
2016-02-02 12:29 ` H.J. Lu
2016-02-02 12:29 ` Jakub Jelinek
2016-02-02 12:30 ` H.J. Lu [this message]
2016-02-02 12:46 ` H.J. Lu
2016-02-02 13:04 ` Ilya Enkovich
2016-02-02 13:06 ` H.J. Lu
2016-02-02 13:08 ` Uros Bizjak
2016-02-02 13:11 ` Ilya Enkovich
2016-02-02 13:14 ` H.J. Lu
2016-02-02 13:21 ` Ilya Enkovich
2016-02-02 13:25 ` H.J. Lu
2016-02-02 13:55 ` Ilya Enkovich
2016-02-02 14:03 ` H.J. Lu
2016-02-02 14:09 ` Ilya Enkovich
2016-02-03 20:11 ` Jakub Jelinek
2016-02-04 8:02 ` Uros Bizjak
2016-02-04 19:47 ` H.J. Lu
2016-02-02 13:09 ` Jakub Jelinek
2016-02-02 13:17 ` H.J. Lu
2016-01-27 16:02 ` H.J. Lu
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