[Bug tree-optimization/61437] New: wrong code on x86_64-linux-gnu when compile separately

[Bug tree-optimization/61437] New: wrong code on x86_64-linux-gnu when compile separately

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61437

            Bug ID: 61437
           Summary: wrong code on x86_64-linux-gnu when compile separately
           Product: gcc
           Version: 4.10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu

The current gcc trunk miscompiles the following files (foo.c and main.c) on
x86_64-linux in both 32-bit and 64-bit modes. 

This is a regression from 4.9.x. 

The merged file (merged.c) does not trigger the bug.


$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-unknown-linux-gnu/4.10.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-trunk/configure --prefix=/usr/local/gcc-trunk
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 4.10.0 20140606 (experimental) [trunk revision 211322] (GCC) 
$ 
$ gcc-trunk -O2 -c foo.c
$ gcc-trunk -O2 -c main.c
$ gcc-trunk -O2 foo.o main.o
$ a.out
a.out: foo.c:9: foo: Assertion `b == 0' failed.
Aborted (core dumped)
$ 
$ gcc-4.9.0 -O2 -c foo.c
$ gcc-4.9.0 -O2 -c main.c
$ gcc-4.9.0 -O2 foo.o main.o
$ a.out
$ 
$ gcc-trunk -O2 merged.c
$ a.out
$ 
$ cat foo.c
#include <assert.h>

extern int *b, **c; 

int foo (void)
{
  int *t = 0; 
  *c = t;
  assert (b == 0);
}
$ cat main.c
extern int foo (void); 

int a, *b = &a, **c = &b;

int main (void)
{
  foo ();
  return 0;
}
$ 
$ cat merged.c
#include <assert.h>

int a;
int *b = &a;
int **c = &b;

int
foo ()
{
  int *t = 0;
  *c = t;
  assert (b == 0);
}

int
main ()
{
  foo ();
  return 0;
}
$

[Bug tree-optimization/61437] [4.10 Regression] wrong code on x86_64-linux-gnu when compile separately

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61437

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-06-08
                 CC|                            |jakub at gcc dot gnu.org
   Target Milestone|---                         |4.10.0
            Summary|wrong code on               |[4.10 Regression] wrong
                   |x86_64-linux-gnu when       |code on x86_64-linux-gnu
                   |compile separately          |when compile separately
     Ever confirmed|0                           |1

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Started with r211233.

[Bug tree-optimization/61437] [4.10 Regression] wrong code on x86_64-linux-gnu when compile separately

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61437

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Eric has already posted a similar testcase and I have a patch.

[Bug tree-optimization/61437] [4.10 Regression] wrong code on x86_64-linux-gnu when compile separately

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61437

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Wed Jun 11 07:35:36 2014
New Revision: 211436

URL: http://gcc.gnu.org/viewcvs?rev=211436&root=gcc&view=rev
Log:
2014-06-11  Richard Biener  <rguenther@suse.de>

    PR middle-end/61437
    Revert
    2014-06-04  Richard Biener  <rguenther@suse.de>

    * tree.h (may_be_aliased): Trust TREE_ADDRESSABLE from
    TREE_PUBLIC and DECL_EXTERNAL decls.

    * gcc.dg/torture/20140610-1.c: New testcase.
    * gcc.dg/torture/20140610-2.c: Likewise.

Added:
    trunk/gcc/testsuite/gcc.dg/torture/20140610-1.c
    trunk/gcc/testsuite/gcc.dg/torture/20140610-2.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree.h

[Bug tree-optimization/61437] [4.10 Regression] wrong code on x86_64-linux-gnu when compile separately

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61437

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

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

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed by reversion.