[Bug tree-optimization/68990] New: wrong code at -O3 on x86_64-pc-linux-gnu in 32-bit mode.

[chengniansun at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68990

            Bug ID: 68990
           Summary: wrong code at -O3 on x86_64-pc-linux-gnu in 32-bit
                    mode.
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: chengniansun at gmail dot com
  Target Milestone: ---

The following code is miscompiled by the gcc trunk at -O3 in 32-bit mode on 
x86_64-pc-linux-gnu.

$: 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/6.0.0/lto-wrapper
Target: x86_64-pc-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 6.0.0 20151218 (experimental) [trunk revision 231807] (GCC) 
$:
$: gcc-trunk -m32 small.c -w -O3 ; ./a.out
$: gcc-trunk -m32 small.c -w -O2 ; ./a.out
g_95=0
$: gcc-trunk -m32 small.c -w -O0 ; ./a.out
g_95=0
$: 
$: cat small.c
short a;
int b = 1, f;
char c, e = 1;
long long d;
static short fn1() {
    unsigned g, h = 0;
    int i = 0 || d * (b | e);
    char j = a << i, l = a;
    short k;
    int m = -b;
    if (m < b) {
        k = m = b;
        g = (k || l) / (b / e);
        if (b)
            printf("g_95=%lld\n", (long long)a);
    }
    a = b = m;
    if (j || e) {
        h = g;
        i = m;
        g = j * k / (i - d);
        if (m)
            b = j && b;
        e = b * (h & d) || g;
    }
    b = i;
    char n = e || h | d;
    e = i < d & k / n;
    return f;
}

int main() {
    if (fn1())
        if (c)
lbl_2043:
            goto lbl_2043;
    return 0;
}