PR debug/53740
PR debug/52983
PR debug/48866
* dce.c (word_dce_process_block): Check whether inserting debug
temps are needed even for needed insns.
(dce_process_block): Likewise.
* df-problems.c (dead_debug_add): Add comment about multi-regs.
(dead_debug_insert_temp): Likewise.  Don't subreg when we're
setting fewer regs than a multi-reg requires.

From-SVN: r189036