[Bug target/47553] New: ARM neon vld1q_lane_u8 & co. don't accept lanes >= 8

["richard.sandiford at linaro dot org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47553

           Summary: ARM neon vld1q_lane_u8 & co. don't accept lanes >= 8
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: richard.sandiford@linaro.org


The testcase:

#include <arm_neon.h>

uint8x16_t
foo (uint8_t *a, uint8x16_t b)
{
  vst1q_lane_u8 (a, b, 14);
  return vld1q_lane_u8 (a + 0x100, b, 15);
}

fails with:

error: argument must be a constant

The v{ld,st}1q_lane_{u,s,p}8 intrinsic functions are supposed to take a range
between 0 and 15.  The function is then converted to a vld1 or vst1 of one half
of the quad value.  The problem is that the lane predicate doesn't account for
this, and only accepts the 0..7 range that are supported by vld1 and vst1.

The error could be a bit friendlier too; maybe "argument out of range" or
something.  That's a problem in a separate piece of code though, so I'm not
treating it as part of this bug.