Comment 4 for bug 936863

The SEGFAULT occurs in arm_print_operand as it tries to write out the final assembler code for remap_stereo_to_mono_neon.

The instruction is:

(insn:TI 15 50 18 4 (set (mem/s:V4SF (reg/v/f:SI 1 r1 [orig:138 dst ] [138]) [0 *(void[16] *) dst_2(D)+0 A8])
        (unspec:V4SF [
                (reg/v:V4SF 95 d16 [orig:135 mono ] [135])
            ] 179)) <path>/arm_neon.h:8316 1578 {neon_vst1v4sf}
     (expr_list:REG_DEAD (reg/v:V4SF 95 d16 [orig:135 mono ] [135])
        (nil)))

The failure is in trying to get the "MEM_SIZE" for "(mem/s:V4SF (reg/v/f:SI 1 r1))" - MEM_SIZE returns an unexpected null-pointer.