re PR target/39431 (ICE in spill_failure, at reload1.c:2093)
PR target/39431
* config/i386/predicates.md (cmpxchg8b_pic_memory_operand): New
predicate.
* config/i386/sync.md (sync_compare_and_swap<mode>,
sync_compare_and_swap_cc<mode>): For DImode with -m32 -fpic check
if operands[1] is cmpxchg8b_pic_memory_operand, if not force address
into a register.
(sync_double_compare_and_swapdi_pic,
sync_double_compare_and_swap_ccdi_pic): Require operand 1 to be
cmpxchg8b_pic_memory_operand instead of just memory_operand.