From: Richard Biener <rguenther@suse.de>
To: Martin Sebor <msebor@gmail.com>
Cc: Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org>,
gcc Patches <gcc-patches@gcc.gnu.org>,
Jan Hubicka <hubicka@ucw.cz>
Subject: Re: [RFC] propagate malloc attribute in ipa-pure-const pass
Date: Thu, 18 May 2017 07:07:00 -0000 [thread overview]
Message-ID: <alpine.LSU.2.20.1705180906070.20726@zhemvz.fhfr.qr> (raw)
In-Reply-To: <89e261a6-1ebd-0e8a-fdf3-4fce98a40ca8@gmail.com>
On Wed, 17 May 2017, Martin Sebor wrote:
> > The patch passes bootstrap+test on x86_64 and found a few functions in
> > the source tree (attached func_names.txt) that could be annotated with
> > malloc (I gave a brief look at some of the functions and didn't appear
> > to be false positives but I will recheck thoroughly)
>
> virtual char* libcp1::compiler::find(std::__cxx11::string&) const
>
> The virtual on the list of your candidates gave me pause. Consider
> this completely contrived example:
>
> struct B {
> virtual void* f (unsigned n) {
> return new char [n];
> }
> };
>
> void* foo (B &b, unsigned n)
> {
> return b.f (n);
> }
>
> Based on these definitions alone both functions are candidates
> for attribute malloc.
>
> But suppose foo is called with an object of a type derived from
> B that overrides f() to do something wacky (but strictly not
> invalid) like:
>
> struct D: B {
> char buf[32];
> virtual void* f (unsigned n) {
> if (n < 32)
> return n <= 32 ? buf : B::f (n);
> }
>
> Breaking foo's attribute malloc constraint.
>
> In other words, I think virtual functions need to be excluded
> from the list (unless they're defined in a class marked final,
> or unless we know they're not overridden to break the constraint
> like above).
But we are annotating the actual decl, not the type in the class
struct.
Richard.
next prev parent reply other threads:[~2017-05-18 7:06 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-15 10:56 Prathamesh Kulkarni
2017-05-16 1:14 ` Jeff Law
2017-05-16 11:48 ` Richard Biener
2017-05-17 21:22 ` Martin Sebor
2017-05-18 7:07 ` Richard Biener [this message]
2017-05-19 13:18 ` Jan Hubicka
2017-05-19 13:34 ` Jan Hubicka
2017-05-23 13:48 ` Prathamesh Kulkarni
2017-07-31 18:23 ` Prathamesh Kulkarni
2017-08-08 4:21 ` Prathamesh Kulkarni
2017-08-17 12:55 ` Prathamesh Kulkarni
2017-09-01 2:39 ` Prathamesh Kulkarni
2017-09-15 12:19 ` Prathamesh Kulkarni
2017-09-25 18:13 ` Prathamesh Kulkarni
2017-09-26 0:24 ` Jan Hubicka
2017-09-27 1:11 ` Prathamesh Kulkarni
2017-09-29 19:28 ` Jan Hubicka
2017-10-06 2:16 ` Prathamesh Kulkarni
2017-10-06 13:04 ` Jan Hubicka
2017-10-07 1:46 ` Prathamesh Kulkarni
2017-10-07 19:35 ` Jan Hubicka
2017-10-07 22:17 ` Prathamesh Kulkarni
2017-10-13 23:34 ` Prathamesh Kulkarni
2017-10-23 9:37 ` Prathamesh Kulkarni
2017-10-24 10:57 ` Jan Hubicka
2017-10-25 11:18 ` Prathamesh Kulkarni
2017-10-25 15:26 ` Jan Hubicka
2017-10-27 10:52 ` Prathamesh Kulkarni
2017-10-27 12:20 ` Jan Hubicka
2017-10-27 12:44 ` Jan Hubicka
2017-10-27 13:00 ` Richard Biener
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