[Bug tree-optimization/61869] New: Spurious uninitialized warning

[Bug tree-optimization/61869] New: Spurious uninitialized warning

[y.gribov at samsung dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61869

            Bug ID: 61869
           Summary: Spurious uninitialized warning
           Product: gcc
           Version: 4.10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: y.gribov at samsung dot com
                CC: jakub at gcc dot gnu.org
              Host: x86_64-unknown-linux-gnu
            Target: x86_64-unknown-linux-gnu

Created attachment 33167
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33167&action=edit
Reprocase

Current gcc reports spurious warning on attached code (based upon gcc/asan.c
with some local changes):
 $ g++ repro.i -c -Wmaybe-uninitialized -O2 
/home/ygribov/repro.i: In function ‘void f(list*)’:
/home/ygribov/repro.i:30:12: warning: ‘i’ may be used uninitialized in this
function [-Wmaybe-uninitialized]
   iterator i;
            ^
/home/ygribov/repro.i:30:12: warning: ‘*((void*)& i +8)’ may be used
uninitialized in this function [-Wmaybe-uninitialized]

It looks like lim1 pass exploits conditional NULL dereference in start() and
introduces read of uninitialized variable.
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From: "dzidzitop at vfemail dot net" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/61870] New: internal compiler error: in get_expr_operands, at tree-ssa-operands.c:1035
Date: Mon, 21 Jul 2014 14:22:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?ida870

            Bug ID: 61870
           Summary: internal compiler error: in get_expr_operands, at
                    tree-ssa-operands.c:1035
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dzidzitop at vfemail dot net

When I compile source code I see the following error.

src/lastfm_scrobbler.cpp: In lambda function:
src/lastfm_scrobbler.cpp:193:1: internal compiler error: in get_expr_operands,
at tree-ssa-operands.c:1035
Please submit a full bug report,
with preprocessed source if appropriate.
See <file:///usr/share/doc/gcc-4.7/README.Bugs> for instructions.
Preprocessed source stored into /tmp/cc6F4c5e.out file, please attach this to
your bugreport.

The line that does not compile is:
m_scrobblingThread = std::thread([this]() { backgroundScrobbling(); });

The following change fixes this:
m_scrobblingThread = std::thread([this]() { this->backgroundScrobbling(); });

[Bug tree-optimization/61869] Spurious uninitialized warning

[manu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61869

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-07-21
                 CC|                            |manu at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #1 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to Yury Gribov from comment #0)
> Created attachment 33167 [details]
> /home/ygribov/repro.i:30:12: warning: ‘*((void*)& i +8)’ may be used
> uninitialized in this function [-Wmaybe-uninitialized]

Sad we are still printing this **** to the user (even if the warning were
valid)
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Subject: [Bug middle-end/61396] [4.10 regression] ICE in simplify_immed_subreg
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https://gcc.gnu.org/bugzilla/show_bug.cgi?ida396

--- Comment #4 from Pat Haugen <pthaugen at gcc dot gnu.org> ---
(In reply to Iain Sandoe from comment #3)
> Revision r209530 is OK, r210534 is not, likely a wide-int fallout.
>
The problem first appeared in trunk revision 210113.

[Bug tree-optimization/61869] Spurious uninitialized warning (lim1 pass, pretty-printed internal var)

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61869

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
      Known to work|                            |5.3.0, 6.3.0
   Target Milestone|---                         |7.0
         Resolution|---                         |FIXED
                 CC|                            |msebor at gcc dot gnu.org

--- Comment #2 from Martin Sebor <msebor at gcc dot gnu.org> ---
Fixed in r245840.

[Bug tree-optimization/61869] Spurious uninitialized warning (lim1 pass, pretty-printed internal var)

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61869

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Martin Sebor <msebor@gcc.gnu.org>:

https://gcc.gnu.org/g:af739c8797d4cdf550366d0ef48136e0073df5c9

commit r11-7899-gaf739c8797d4cdf550366d0ef48136e0073df5c9
Author: Martin Sebor <msebor@redhat.com>
Date:   Mon Mar 29 15:58:01 2021 -0600

    PR tree-optimization/61869 - Spurious uninitialized warning

    gcc/testsuite/ChangeLog:
            PR tree-optimization/61869
            * gcc.dg/uninit-pr61869.c: New test.