[Bug tree-optimization/27768] New: [4.2 regression] wrong-code with vectors

[Bug tree-optimization/27768] New: [4.2 regression] wrong-code with vectors

[reichelt at gcc dot gnu dot org]

The following code crashes when I compile it with -O2 (mainline)

==========================
#include<vector>

struct A
{
    std::vector<int> v;
    char             c;
};

struct B {};

int main()
{
    A a;
    A a2(a);
    std::vector<B*> b;
    return 0;
}
==========================

The program dies with:

*** glibc detected *** free(): invalid pointer: 0x00002aaaaabc0c60 ***
zsh: 13987 abort      a.out

I'll come up with a reduced testcase next week if nobody beats me.

Happens only with mainline, -O1 is not affected.


-- 
           Summary: [4.2 regression] wrong-code with vectors
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: reichelt at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug tree-optimization/27768] [4.2 regression] wrong-code with vectors

[reichelt at gcc dot gnu dot org]

------- Comment #1 from reichelt at gcc dot gnu dot org  2006-05-25 08:30 -------
Btw, this is on x86_64-unknown-linux-gnu.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug tree-optimization/27768] [4.2 regression] wrong-code with vectors

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu dot
                   |                            |org
 GCC target triplet|                            |x86_64-unknown-linux-gnu
   Target Milestone|---                         |4.2.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug tree-optimization/27768] [4.2 regression] wrong-code with vectors

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2006-05-28 20:47 -------
Something is removing the store to _M_start.

  this_252 = (struct _Vector_base<B*,std::allocator<B*> > *) &b;
  this_253 = this_252;
  #   VUSE <SMT.84_402>;
  D.13530_256 = this_252->_M_impl._M_start;


I think the cast there is causing the problem.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug tree-optimization/27768] [4.2 regression] wrong-code with vectors

[pinskia at gcc dot gnu dot org]

------- Comment #3 from pinskia at gcc dot gnu dot org  2006-05-28 20:50 -------
This is related to PR 19817, the C++ front-end is producing that construct
which causes us not to constant prop zero.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug c++/27768] [4.2 regression] wrong-code with vectors

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2006-05-28 20:52 -------
But even without fixing PR 19817, it seems like the cast should be valid, or
maybe not someone who knows if the cast is valid in C++ where the struct is not
an inheirtance.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  BugsThisDependsOn|                            |19817
          Component|tree-optimization           |c++


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug c++/27768] [4.2 regression] wrong-code with vectors

[reichelt at gcc dot gnu dot org]

------- Comment #5 from reichelt at gcc dot gnu dot org  2006-05-30 16:02 -------
Created an attachment (id=11539)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=11539&action=view)
reduced testcase


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug tree-optimization/27768] [4.2 regression] wrong-code with vectors

[reichelt at gcc dot gnu dot org]

------- Comment #6 from reichelt at gcc dot gnu dot org  2006-05-30 16:05 -------
I think there's something hosed with aliasing.
The code crashes with -O2, but runs fine with -O2 -fno-strict-aliasing.


-- 

reichelt at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |critical
          Component|c++                         |tree-optimization
           Keywords|                            |monitored


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug c++/27768] [4.2 regression] wrong-code with vectors

[pinskia at gcc dot gnu dot org]

------- Comment #7 from pinskia at gcc dot gnu dot org  2006-05-30 16:06 -------
I already mentioned this is most likely a C++ front-end.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
          Component|tree-optimization           |c++
     Ever Confirmed|0                           |1
           Keywords|                            |alias
   Last reconfirmed|0000-00-00 00:00:00         |2006-05-30 16:06:59
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug c++/27768] [4.2 regression] wrong-code with vectors

[reichelt at gcc dot gnu dot org]

------- Comment #8 from reichelt at gcc dot gnu dot org  2006-05-31 11:07 -------
Created an attachment (id=11550)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=11550&action=view)
modified testcase


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug c++/27768] [4.1/4.2 regression] wrong-code with vectors

[reichelt at gcc dot gnu dot org]

------- Comment #9 from reichelt at gcc dot gnu dot org  2006-05-31 11:13 -------
The modified testcase from comment #8 should return 0,
but returns 255 (a.k.a -1) when compiled with -O2.

The bad news is that this also affects the 4.1 branch (4.1.0 and later).
The failure on the 4.1 branch is not reproducible with -m32
whereas mainline also crashes with -m32.

The testcase from comment #5 also crashes with 4.1.0 (without -m32),
but not with 4.1.1.


-- 

reichelt at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.2 regression] wrong-code |[4.1/4.2 regression] wrong-
                   |with vectors                |code with vectors
   Target Milestone|4.2.0                       |4.1.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug c++/27768] [4.1/4.2 regression] wrong-code with vectors

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug c++/27768] [4.1/4.2 regression] wrong-code with vectors

[bangerth at dealii dot org]

------- Comment #10 from bangerth at dealii dot org  2006-06-15 03:45 -------
This problem persists with gcc4.1.x from 2006-06-13. I believe I get the
same glibc fault in one of my codes, which isn't particularly surprising
given that Volker used widely used std:: components in his program as well...

Definitely an important bug!

W.


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bangerth at dealii dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bangerth at dealii dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug c++/27768] [4.1/4.2 regression] wrong-code with vectors

[jason at gcc dot gnu dot org]

-- 

jason at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jason at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2006-05-30 16:06:59         |2006-06-26 22:24:39
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug c++/27768] [4.1/4.2 regression] wrong-code with vectors

[jason at gcc dot gnu dot org]

------- Comment #11 from jason at gcc dot gnu dot org  2006-06-28 19:12 -------
Turns out to be a bug in alias grouping.  Patch in testing.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug c++/27768] [4.1/4.2 regression] wrong-code with vectors

[jason at gcc dot gnu dot org]

------- Comment #12 from jason at gcc dot gnu dot org  2006-06-29 01:12 -------
Subject: Bug 27768

Author: jason
Date: Thu Jun 29 01:12:20 2006
New Revision: 115062

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=115062
Log:
        PR c++/27768
        * tree-ssa-alias.c (compute_flow_insensitive_aliasing): Add
        may_aliases already in the tag's annotations to the bitmap.

Added:
    trunk/gcc/testsuite/g++.dg/opt/alias4.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/tree-ssa-alias.c


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug c++/27768] [4.1 regression] wrong-code with vectors

[pinskia at gcc dot gnu dot org]

------- Comment #13 from pinskia at gcc dot gnu dot org  2006-06-29 13:49 -------
Fixed on the mainline at least.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |4.1.0 4.1.1
      Known to work|                            |4.0.0
            Summary|[4.1/4.2 regression] wrong- |[4.1 regression] wrong-code
                   |code with vectors           |with vectors


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug c++/27768] [4.1 regression] wrong-code with vectors

[jason at gcc dot gnu dot org]

------- Comment #14 from jason at gcc dot gnu dot org  2006-06-30 15:19 -------
Subject: Bug 27768

Author: jason
Date: Fri Jun 30 15:19:50 2006
New Revision: 115090

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=115090
Log:
        PR c++/27768
        * tree-ssa-alias.c (compute_flow_insensitive_aliasing): Add
        may_aliases already in the tag's annotations to the bitmap.

Added:
    branches/gcc-4_1-branch/gcc/testsuite/g++.dg/opt/alias4.C
      - copied unchanged from r115062, trunk/gcc/testsuite/g++.dg/opt/alias4.C
Modified:
    branches/gcc-4_1-branch/gcc/ChangeLog
    branches/gcc-4_1-branch/gcc/tree-ssa-alias.c


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768

[Bug c++/27768] [4.1 regression] wrong-code with vectors

[pinskia at gcc dot gnu dot org]

------- Comment #15 from pinskia at gcc dot gnu dot org  2006-06-30 15:25 -------
Fixed.


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pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27768