http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60116
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |ebotcazou at gcc dot gnu.org,
| |law at gcc dot gnu.org
--- Comment #13 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So, what happens is that we have:
(insn 39 38 41 5 (set (reg:QI 119)
(const_int 1 [0x1])) pr60116.c:17 93 {*movqi_internal}
(expr_list:REG_DEAD (reg:CCZ 17 flags)
(nil)))
(insn 41 39 83 5 (set (reg:CCZ 17 flags)
(compare:CCZ (reg:SI 101 [ D.1460 ])
(const_int 0 [0]))) pr60116.c:18 3 {*cmpsi_ccno_1}
(nil))
(insn 83 41 42 5 (set (reg:SI 122 [ D.1465 ])
(zero_extend:SI (reg:QI 119))) 138 {*zero_extendqisi2}
(expr_list:REG_DEAD (reg:QI 119)
(nil)))
(the REG_DEAD on flags on the first insn supposedly comes from earlier
combining.
try_combine is then called on i3=insn83 and i2=insn39 and manages to combine
insn 83 into (set (reg:SI 122) (const_int 1 [0x1])).
The problem is when distribute_notes attempts to distribute the REG_DEAD
(reg:CCZ 17 flags) note from elim_i2=insn39 to i3=insn83.
