[Bug tree-optimization/59221] New: wrong code at -O2 and -O3 on x86_64-linux-gnu

[Bug tree-optimization/59221] New: wrong code at -O2 and -O3 on x86_64-linux-gnu

[su at cs dot ucdavis.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59221

            Bug ID: 59221
           Summary: wrong code at -O2 and -O3 on x86_64-linux-gnu
           Product: gcc
           Version: 4.9.0
            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 code on x86_64-linux at -O2 and
-O3 in both 32-bit and 64-bit modes. 

This is a regression from 4.8.x. 

$ 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/4.9.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-trunk/configure
--enable-languages=c,c++,objc,obj-c++,fortran,lto --disable-werror
--with-gmp=/usr/local/gcc-trunk --with-mpfr=/usr/local/gcc-trunk
--with-mpc=/usr/local/gcc-trunk --with-cloog=/usr/local/gcc-trunk
--prefix=/usr/local/gcc-trunk
Thread model: posix
gcc version 4.9.0 20131120 (experimental) [trunk revision 205097] (GCC) 
$ 
$ gcc-trunk -Os small.c; a.out
$ gcc-4.8.2 -O2 small.c; a.out
$ 
$ gcc-trunk -O2 small.c; a.out
Aborted (core dumped)
$ 


-----------------------


int a = 1, b, d;
short e;

int
main ()
{
  for (; b; b++)
    ;
  short f = a;
  int g = 15;
  e = f ? f : 1 << g;
  int h = e;
  d = h == 83647 ? 0 : h;
  if (d != 1)
    __builtin_abort ();
  return 0;
}

[Bug tree-optimization/59221] [4.9 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59221

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-11-21
   Target Milestone|---                         |4.9.0
            Summary|wrong code at -O2 and -O3   |[4.9 Regression] wrong code
                   |on x86_64-linux-gnu         |at -O2 and -O3 on
                   |                            |x86_64-linux-gnu
     Ever confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed, disabling VRP fixes it.

[Bug tree-optimization/59221] [4.9 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59221

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

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

[Bug tree-optimization/59221] [4.9 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59221

--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> ---
It is caused by r205074.

[Bug tree-optimization/59221] [4.9 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu

[law at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59221

--- Comment #4 from Jeffrey A. Law <law at redhat dot com> ---
Patch testing now.

[Bug tree-optimization/59221] [4.9 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu

[law at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59221

--- Comment #5 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Author: law
Date: Thu Nov 21 19:45:16 2013
New Revision: 205229

URL: http://gcc.gnu.org/viewcvs?rev=205229&root=gcc&view=rev
Log:
    PR tree-optimization/59221
    * tree-ssa-threadedge.c (thread_across_edge): Properly manage
    temporary equivalences when threading through joiner blocks.

    PR tree-optimization/59221
    * gcc.c-torture/execute/pr59221.c: New test.

Added:
    trunk/gcc/testsuite/gcc.c-torture/execute/pr59221.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-threadedge.c

[Bug tree-optimization/59221] [4.9 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu

[law at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59221

Jeffrey A. Law <law at redhat dot com> changed:

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

--- Comment #6 from Jeffrey A. Law <law at redhat dot com> ---
Fixed on trunk.  Again, sorry for the breakage.

[Bug tree-optimization/59221] [4.9 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu

[su at cs dot ucdavis.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59221

--- Comment #7 from Zhendong Su <su at cs dot ucdavis.edu> ---
(In reply to Jeffrey A. Law from comment #6)
> Fixed on trunk.  Again, sorry for the breakage.

Thanks Jeff. That was quick!

[Bug tree-optimization/59221] [4.9 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu

[law at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59221

Jeffrey A. Law <law at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ro at gcc dot gnu.org

--- Comment #8 from Jeffrey A. Law <law at redhat dot com> ---
*** Bug 59235 has been marked as a duplicate of this bug. ***