From: Martin Sebor <msebor@gmail.com>
To: Richard Biener <richard.guenther@gmail.com>
Cc: Gcc Patch List <gcc-patches@gcc.gnu.org>
Subject: Re: enable -Wformat-truncation with -Og (PR 79691)
Date: Fri, 24 Feb 2017 18:20:00 -0000 [thread overview]
Message-ID: <d836836d-89a0-c6fa-a5f8-cbfa56d040ea@gmail.com> (raw)
In-Reply-To: <CAFiYyc0gWCJPczDWMpgJ5vT9ZCkHVq5h=mu59A7oUe+DE0Vm4A@mail.gmail.com>
On 02/24/2017 03:10 AM, Richard Biener wrote:
> On Fri, Feb 24, 2017 at 1:35 AM, Martin Sebor <msebor@gmail.com> wrote:
>> Bug 79691 - -Wformat-truncation suppressed by (and only by) -Og
>> points out that the gimple-ssa-sprintf pass doesn't run when
>> this optimization option is used. That's because I forgot to
>> add it to the set of optimization passes that run with that
>> option. The attached trivial patch tested on x86_64 corrects
>> the oversight.
>>
>> Is this okay for 7.0?
>
> Any reason for the placement before copy-prop? I'd have done it
> after pass_late_warn_uninitialized for example.
I wanted to make sure that folded sprintf return values would be
eligible for further copy propagation. E.g., that a + b would
be folded into a constant:
int foo (void)
{
int a = snprintf (0, 0, "%i", 123);
int b = snprintf (0, 0, "%i", 1234);
return a + b;
}
But I could have easily missed some important use case where this
placement will compromise the warning. I don't have any tests
for this one way or the other so I'm happy to go with your
recommendation. Let me know which you think is more appropriate
(if you have a suggestion for a test case I'd be grateful).
>
> Also doesn't pass_sprintf_length rely on get_range_info ()? With -Og
> nothing populates those so you'll always get effectively VARYING ranges.
It does when it's available but as Jakub noted, it works without
it as well (at -O0).
Thanks
Martin
next prev parent reply other threads:[~2017-02-24 17:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-24 5:07 Martin Sebor
2017-02-24 10:14 ` Richard Biener
2017-02-24 10:22 ` Jakub Jelinek
2017-02-24 18:20 ` Martin Sebor [this message]
2017-02-27 8:49 ` Richard Biener
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