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From: "su at cs dot ucdavis.edu" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/58759] New: wrong code (segfaults) at -O2 on x86_64-linux-gnu in 32-bit mode
Date: Wed, 16 Oct 2013 22:00:00 -0000
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X-Bugzilla-Type: new
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 4.9.0
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X-Bugzilla-Who: su at cs dot ucdavis.edu
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58759

            Bug ID: 58759
           Summary: wrong code (segfaults) at -O2 on x86_64-linux-gnu in
                    32-bit mode
           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 in
32-bit mode. 

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
--enable-checking=release --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 20131016 (experimental) [trunk revision 203716] (GCC) 
$ 
$ gcc-trunk -m32 -Os small.c; a.out
$ gcc-trunk -m32 -O3 small.c; a.out
$ gcc-trunk -m64 -O2 small.c; a.out
$ 
$ gcc-trunk -m32 -O2 small.c; a.out
Segmentation fault (core dumped)
$ 
$ gcc-4.8 -m32 -O2 small.c; a.out
$ 


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


int a, b, c, d, e, f, h, l, m, n, k, o;
long long g;

struct S
{
  int f1;
  int f2;
  int f3;
  int f4;
};

static struct S i = {0,0,0,0}, j;

void
foo ()
{
  m = 1 & d;
  n = b + c;
  o = k >> 1;
  f = 0 == e;
}

int
main ()
{
  for (; h < 1; h++)
    {
      g = 1 | (0 > 1 - a ? 0 : a);
      foo ();
      for (l = 0; l < 3; l++)
    j = i;
    }
  return 0;
}