[Bug middle-end/48028] New: [4.4 Regression] undeserved uninitialized variable warning regression since 4.4.2

[Bug middle-end/48028] New: [4.4 Regression] undeserved uninitialized variable warning regression since 4.4.2

[matt at use dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48028

           Summary: [4.4 Regression] undeserved uninitialized variable
                    warning regression since 4.4.2
           Product: gcc
           Version: 4.4.5
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: matt@use.net


I have several instances of undeserved uninitialized variable warnings since
upgrading from 4.4.2 to 4.4.5. Oddly, they only seem to come up in 64-bit
targets, but I'm not sure if that's consistent. 

I have attached the pre-processed sources for two examples. One is from
kerberos5 sources.

[Bug middle-end/48028] [4.4 Regression] undeserved uninitialized variable warning regression since 4.4.2

[matt at use dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48028

--- Comment #1 from Matt Hargett <matt at use dot net> 2011-03-08 00:06:26 UTC ---
Created attachment 23580
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23580
pre-processed source of the file that triggers the -Wuninitialized warning
regression on x86-64

[Bug middle-end/48028] [4.4 Regression] undeserved uninitialized variable warning regression since 4.4.2

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48028

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-03-08 00:19:48 UTC ---
So the code looks like (after inlining and folding of *&):
int f(void);
int g1(void);
void g2(int);

int g(void)
{
  int selret;
  int e = 0;
  while (1)
  {
    e = f();
    if (e!= 0)
      selret = g1();
    if (e==4)
      continue;
    if (e!=0)
      break;
    g2(selret);
  }
  return 0;
}

[Bug middle-end/48028] [4.4 Regression] undeserved uninitialized variable warning regression since 4.4.2

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48028

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-03-08 00:20:39 UTC ---
(In reply to comment #2)
> So the code looks like (after inlining and folding of *&):
Woops that is wrong, the first e!=0 should have been == 0 but we don't warn
there, hmm.

[Bug middle-end/48028] [4.3/4.4 Regression] undeserved uninitialized variable warning regression since 4.4.2

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48028

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011.03.08 10:55:41
      Known to work|                            |4.2.4, 4.4.0, 4.4.3, 4.5.2,
                   |                            |4.6.0
   Target Milestone|---                         |4.3.6
            Summary|[4.4 Regression] undeserved |[4.3/4.4 Regression]
                   |uninitialized variable      |undeserved uninitialized
                   |warning regression since    |variable warning regression
                   |4.4.2                       |since 4.4.2
     Ever Confirmed|0                           |1
      Known to fail|                            |4.3.0, 4.3.5, 4.4.4

--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-03-08 10:55:41 UTC ---
Only happens at -O3, so probably needs inlining to trigger and is susceptible
to inline heuristic changes.  4.5 works fine.

[Bug middle-end/48028] [4.3/4.4 Regression] undeserved uninitialized variable warning regression since 4.4.2

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48028

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2

[Bug middle-end/48028] [4.3/4.4 Regression] undeserved uninitialized variable warning regression since 4.4.2

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48028

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.3.6                       |4.4.7

--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-06-27 12:13:46 UTC ---
4.3 branch is being closed, moving to 4.4.7 target.

[Bug middle-end/48028] [4.4 Regression] undeserved uninitialized variable warning regression since 4.4.2

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48028

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |jakub at gcc dot gnu.org
         Resolution|                            |FIXED
   Target Milestone|4.4.7                       |4.5.2

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-03-13 13:26:47 UTC ---
Fixed in 4.5+, 4.4 is no longer supported.