https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63740
--- Comment #15 from Vladimir Makarov <vmakarov at gcc dot gnu.org> ---
The insn in question is
(insn 3598 3597 6907 395 (parallel [
(set (reg:CC 100 cc)
(compare:CC (reg:SI 307 [ ls$2 ])
(const_int 0 [0])))
(set (reg:SI 192 [ D.62648 ])
(reg:SI 307 [ ls$2 ]))
]) ../../gcc-4.9.2/gcc/haifa-sched.c:6368 204 {*movsi_compare0}
(expr_list:REG_DEAD (reg:SI 307 [ ls$2 ])
(expr_list:REG_UNUSED (reg:CC 100 cc)
(nil))))
The insn definition is
(define_insn "*movsi_compare0"
[(set (reg:CC CC_REGNUM)
(compare:CC (match_operand:SI 1 "s_register_operand" "0,r")
(const_int 0)))
(set (match_operand:SI 0 "s_register_operand" "=r,r")
(match_dup 1))]
LRA choosing the first alternative where the 0 and 1 operand should be the same
and generates
(insn 3598 7755 7756 395 (parallel [
(set (reg:CC 100 cc)
(compare:CC (reg:SI 3686 [orig:192 D.62648 ] [192])
(const_int 0 [0])))
(set (reg:SI 3686 [orig:192 D.62648 ] [192])
(reg:SI 3686 [orig:192 D.62648 ] [192]))
]) ../../gcc-4.9.2/gcc/haifa-sched.c:6368 204 {*movsi_compare0}
(expr_list:REG_DEAD (reg:SI 307 [ ls$2 ])
(expr_list:REG_UNUSED (reg:CC 100 cc)
(nil))))
The generated ins is ok. The code in lra_lives.c::process_bb_lives is
if (dst_regno >= lra_constraint_new_regno_start
&& src_regno >= lra_constraint_new_regno_start)
lra_create_copy (dst_regno, src_regno, freq);
The code was written to process reload insns only but insn 3598 looks like
reload because it is a single_set insn (reg 100 is unused).
lra_create_copy has an assertion that dst_regno and src_regno are different
which fails.
The fix should be trivial. I'll commit it soon.
