Extended Description

The following code is miscompiled by the current clang trunk and clang 3.3 on x86_64-linux-gnu at -Os and -O3 in 64-bit mode (but not 32-bit mode).

This is a regression from clang 3.2.

$ clang-trunk -v
clang version 3.5 (trunk 195973)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.3
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
$
$ clang-trunk -O1 small.c; a.out
0
$ clang-trunk -O2 small.c; a.out
0
$ clang-3.2 -Os small.c; a.out
0
$
$ clang-trunk -Os small.c; a.out
1
$ clang-3.3 -Os small.c; a.out
1
$

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

int a, b, c, d, f, g;

struct S0
{
char f0;
int f1;
int f2;
} e, u;

int
fn1 ()
{
return b;
}

int
fn2 ()
{
struct S0 j = { 0, 0, 1 };
e = j;
if (fn1 () >= 0)
{
e.f2 = 0;
j = u;
}
else
for (;;)
for (e.f2 = 0; e.f2 < 1;)
if (d)
return 0;
for (; j.f0; j.f0++)
{
if (g)
e.f1 = j.f1;
f = a || 1 >> c ? 0 >> c : 1;
}
return 0;
}

int
main ()
{
fn2 ();
printf ("%d\n", e.f2);
return 0;
}