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From: "jakub 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: Tue, 26 Apr 2022 09:56:06 +0000	[thread overview]
Message-ID: <bug-105346-4-owBa2AC9cT@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 #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Started with r11-5732-gdce6c58db87ebf7f4477bd3126228e73e4eeee97
The IL at -O0 -Wall looks during waccess pass like:
void foo ()
{
  char * bufp;
  char buf[20];

  <bb 2> :
  bufp_2 = &buf;
  if (&buf != bufp_2)
    goto <bb 3>; [INV]
  else
    goto <bb 4>; [INV]

  <bb 3> :
  __builtin_free (bufp_2);

  <bb 4> :
  buf ={v} {CLOBBER(eol)};
  return;

}

So, I think the waccess pass must be walking SSA_NAME_DEF_STMT to figure out it
is a free of non-heap.  Either it shouldn't do that at -O0, or it should only
walk them when they are in the same bb as the free call, or it needs to be able
to detect also conditionals like the above.

  parent reply	other threads:[~2022-04-26  9:56 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 [this message]
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
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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