[Bug tree-optimization/56157] [4.8 Regression] ICE with -ftree-vectorize in in compute_live_loop_exits

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56157

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> 2013-01-31 11:54:09 UTC ---
Reduced testcase:

struct Pixel {
    unsigned short r;
    unsigned short g;
    unsigned short b;
    unsigned short a;
};

void fn(unsigned char *dst, const unsigned char *src, unsigned width)
{
  unsigned x;
  for(x = 0; x < width; x += 1)
    {
      struct Pixel pixel;
      pixel.r = (unsigned short)(((unsigned)src[0]) * 0xffff / 0xff);
      pixel.g = (unsigned short)(((unsigned)src[1]) * 0xffff / 0xff);
      pixel.b = (unsigned short)(((unsigned)src[2]) * 0xffff / 0xff);
      pixel.a = (unsigned short)(((unsigned)src[3]) * 0xffff / 0xff);
      __builtin_memcpy(dst, &pixel, sizeof pixel);
      src += 4;
      dst += 8;
    }
}