[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;
}