[Bug tree-optimization/77856] New: wrong code at -O2 on x86_64-linux-gnu in 32-bit mode

["su at cs dot ucdavis.edu" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77856

            Bug ID: 77856
           Summary: wrong code at -O2 on x86_64-linux-gnu in 32-bit mode
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu
  Target Milestone: ---

It is a regression from 6.2.x.


$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto
--prefix=/usr/local/gcc-trunk --disable-bootstrap
Thread model: posix
gcc version 7.0.0 20161004 (experimental) [trunk revision 240755] (GCC) 
$ 
$ gcc-6.2 -m32 -O2 small.c; ./a.out
1
$ gcc-trunk -m32 -Os small.c; ./a.out
1
$ 
$ gcc-trunk -m32 -O2 small.c; ./a.out
64
$ 
$ 


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


int printf (const char *, ...);

unsigned a, e;

struct S0
{
  int f1;
  int f8;
} c = {4, 6};

int b, f, g, h, i, j, l, p;
short d, o = -7;
char k, n = 5;

unsigned fn1 (int p1, int p2)
{
  return p2 >= 2 || p1 >> p2 ? p1 : p1 << p2;
}

static short fn2 (struct S0 p1)
{
  int *q = 0;
  int r = 7;
  if (!a)
    {
      c.f1 = 1;
      for (; c.f1; c.f1--)
        if (fn1 (10 != 0, p1.f8))
          {
            short s = 9 << ~o % (d ^ n);
            int t = s >> h % ~d;
            p = r;
            r = s | p * (d && 9) | t;
            int u = i & c.f1;
            unsigned v = ~(~(u & h) | (~(8 >> c.f1) & i));
            int w = v;
            if (u < 9)
              w = c.f1;
            if (i > h && u)
              {
                printf ("%d\n", c.f1);
                continue;
              }
            c.f1 = w;
            if (!p)
              continue;
            return 0;
          }
      for (;;)
        *q = 0;
    }
  return 0; 
}

static void fn3 ()
{
  fn2 (c);
  l = c.f1 < b;
  if (l)
    {
    L1:
      e = l | j / e % ~f;
      j = f - 4 % k < c.f1 / e / b - j - 1;
      if (l)
        {
          printf ("%d\n", b);
          goto L1;
        }
      int m[245];
      g = m[2];
    }
}

int main ()
{
  fn3 ();
  printf ("%d\n", c.f1);
  return 0; 
}