[Bug rtl-optimization/50891] move2add_note_store fails to properly track register content

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50891

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> 2011-10-27 23:10:45 
UTC ---
reload_cse_move2add treats

(insn 61 60 62 8 (set (reg:CCZ 17 flags)
        (compare:CCZ (reg:SI 2 cx)
            (const_int 3 [0x3]))) x.f90:9 6 {*cmpsi_1}
     (nil))

(jump_insn 62 61 63 8 (set (pc) 
        (if_then_else (ne (reg:CCZ 17 flags)
                (const_int 0 [0]))
            (label_ref 231) 
            (pc))) x.f90:9 589 {*jcc_1}
     (expr_list:REG_BR_PROB (const_int 1400 [0x578])
        (nil))
 -> 231) 

with

(gdb) call debug_rtx (implicit_set)
(set (reg:SI 2 cx)
    (const_int 3 [0x3]))
(gdb) 

at
2046              move2add_note_store (SET_DEST (implicit_set), implicit_set,
insn);

It is wrong.