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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/105346] [11/12 Regression] -Wno-free-nonheap-object false positive (on Bison-generated grammar code)
Date: Wed, 27 Apr 2022 07:15:11 +0000 [thread overview]
Message-ID: <bug-105346-4-iXkXqhEsGp@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-105346-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105346
--- Comment #13 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Andrew Macleod from comment #11)
> (In reply to Richard Biener from comment #6)
>
> >
> > <bb 2> :
> > bufp_2 = &buf;
> > if (&buf != bufp_2)
> > goto <bb 3>; [INV]
> > else
> > goto <bb 4>; [INV]
> >
> > <bb 3> :
> > __builtin_free (bufp_2);
> >
> > and for the stmt __builtin_free (bufp_2) I'd like to ask if we know
> > that bufp_2 is != &buf (I'd expect a 'true' answer). I think the
> > relation oracle should be able to answer this but I can't find the
> > appropriate API to use for this?
>
> - The relation oracle currently only works with ssa-names.
> - Ranger also doesn't currently track that sort of symbolic equivalence with
> irange.
> - the VRP passes have a pointer tracking mechanism as part of the dom walk,
> and the call to rvrp_folder::value_of_expr (bufp_2) would give us &buf. I
> also think we also would fold the stmt in VRP. This could in theory be
> extended to any pass doing a dom walk. however:
> - I believe the upcoming prange extension for pointer ranges in stage 1 will
> make this happen naturally with rangers query system. range_of_stmt ( if
> <..>) would then produce bool [0, 0]. I would also expect that prange will
> have an easy way to ask what its base/equivalence(s) are.
OK, I was hoping I can so sth like
range_simplify_expr (NE_EXPR, bufp_2, &buf, at_free_stmt);
and then by means of the dominating if condition get a 'true'. Note the
diagnostic pass is not within a DOM walk so all I can use is an ad-hoc
query. I'm not looking to simplify the conditional itself as that won't
help me with the current pass structure.
next prev parent reply other threads:[~2022-04-27 7:15 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-22 12:12 [Bug c/105346] New: " tim.vanholder at anubex dot com
2022-04-22 12:21 ` [Bug c/105346] " rguenth at gcc dot gnu.org
2022-04-26 8:10 ` tim.vanholder at anubex dot com
2022-04-26 9:20 ` tim.vanholder at anubex dot com
2022-04-26 9:21 ` [Bug c++/105346] " tim.vanholder at anubex dot com
2022-04-26 9:40 ` rguenth at gcc dot gnu.org
2022-04-26 9:52 ` [Bug middle-end/105346] " rguenth at gcc dot gnu.org
2022-04-26 9:53 ` [Bug middle-end/105346] [11/12 Regression] " rguenth at gcc dot gnu.org
2022-04-26 9:56 ` jakub at gcc dot gnu.org
2022-04-26 10:09 ` rguenther at suse dot de
2022-04-26 10:12 ` jakub at gcc dot gnu.org
2022-04-26 13:53 ` amacleod at redhat dot com
2022-04-26 14:12 ` aldyh at gcc dot gnu.org
2022-04-27 7:15 ` rguenth at gcc dot gnu.org [this message]
2022-04-27 9:06 ` aldyh at gcc dot gnu.org
2022-04-27 9:16 ` rguenth at gcc dot gnu.org
2022-04-27 9:23 ` aldyh at gcc dot gnu.org
2022-04-27 10:17 ` rguenth at gcc dot gnu.org
2023-05-29 10:06 ` [Bug middle-end/105346] [11/12/13/14 " jakub at gcc dot gnu.org
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