gcc-8.0.0-alpha20170507 snapshot ICEs when compiling the following snippet, reduced from the original testcase in PR71012, w/ -O2, -O3, or -Ofast:

typedef char k6 __attribute__ ((vector_size(16)));
typedef int tp __attribute__ ((vector_size(16)));

k6 ap;
tp r3;

void
i5 (k6 x5, k6 nr, int gx)
{
  tp cl = { 1, 1 };

  while (gx < 1)
    {
      ap = x5;
      r3 += gx;
      r3 *= cl;
      ap <<= 1;
      x5 <<= nr;
      ++gx;
    }
}

% powerpc-e500v2-linux-gnuspe-gcc-8.0.0-alpha20170507 -w -O2 -c fiwreogz.c 
fiwreogz.c: In function 'i5':
fiwreogz.c:21:1: internal compiler error: Bus error
 }
 ^
0xc49b79 crash_signal
	/var/tmp/portage/cross-powerpc-e500v2-linux-gnuspe/gcc-8.0.0_alpha20170507/work/gcc-8-20170507/gcc/toplev.c:337
0xb9161c constrain_operands(int, unsigned long)
	/var/tmp/portage/cross-powerpc-e500v2-linux-gnuspe/gcc-8.0.0_alpha20170507/work/gcc-8-20170507/gcc/recog.c:2583
0xb92204 extract_constrain_insn(rtx_insn*)
	/var/tmp/portage/cross-powerpc-e500v2-linux-gnuspe/gcc-8.0.0_alpha20170507/work/gcc-8-20170507/gcc/recog.c:2212
0xa840df check_rtl
	/var/tmp/portage/cross-powerpc-e500v2-linux-gnuspe/gcc-8.0.0_alpha20170507/work/gcc-8-20170507/gcc/lra.c:2128
0xa88d07 lra(_IO_FILE*)
	/var/tmp/portage/cross-powerpc-e500v2-linux-gnuspe/gcc-8.0.0_alpha20170507/work/gcc-8-20170507/gcc/lra.c:2546
0xa34e30 do_reload
	/var/tmp/portage/cross-powerpc-e500v2-linux-gnuspe/gcc-8.0.0_alpha20170507/work/gcc-8-20170507/gcc/ira.c:5472
0xa34e30 execute
	/var/tmp/portage/cross-powerpc-e500v2-linux-gnuspe/gcc-8.0.0_alpha20170507/work/gcc-8-20170507/gcc/ira.c:5656

The snippet builds fine w/ -mno-spe.