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From: "dmalcolm at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug analyzer/106302] New: RFE: provide a way for -fanalyzer to use
 target flags
Date: Thu, 14 Jul 2022 15:35:19 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106302

            Bug ID: 106302
           Summary: RFE: provide a way for -fanalyzer to use target flags
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: analyzer
          Assignee: dmalcolm at gcc dot gnu.org
          Reporter: dmalcolm at gcc dot gnu.org
            Blocks: 106003, 106301
  Target Milestone: ---

As noted in the discussion here:
  https://gcc.gnu.org/pipermail/gcc/2022-June/238954.html
-fanalyzer sometimes uses specific target flags when modeling the behavior =
of
functions, see e.g.: sm-fd.cc, which currently has:

enum access_mode
fd_state_machine::get_access_mode_from_flag (int flag) const
{
  /* FIXME: this code assumes the access modes on the host and
          target are the same, which in practice might not be the case. */

  if ((flag & O_ACCMODE) =3D=3D O_RDONLY)
    {
      return READ_ONLY;
    }
  else if ((flag & O_ACCMODE) =3D=3D O_WRONLY)
    {
      return WRITE_ONLY;
    }
  return READ_WRITE;
}

where we are using the values of O_ACCMODE, O_RDONLY, and O_WRONLY from the
host's headers, rather than those of the target.

See also bug 106301, where properly supporting mmap would mean looking at
values of MAP_ANONYMOUS, and of the various PROT_ values.

Joseph suggested adding a target hook for this, though I think we'd need an
enum for it, so that we can add various different "well known" values that =
we'd
want to query for on the host.  Alternatively, perhaps we could directly qu=
ery
the preprocessor somehow, though that wouldn't work for the LTO case.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106003
[Bug 106003] RFE: -fanalyzer could complain about misuse of file-descriptors
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106301
[Bug 106301] RFE: analyzer support of mmap=