------- Additional Comments From pinskia at gcc dot gnu dot org 2005-02-01
05:57 -------
Hmm, maybe gcc should be able to optimize the following RTL better when
combining them (if gcc
does combine them):
(insn 19 18 20 0 (set (reg:CCZ 17 flags)
(compare:CCZ (zero_extract:SI (subreg:DI (reg:QI 61 [+5 ]) 0)
(const_int 1 [0x1])
(const_int 0 [0x0]))
(const_int 0 [0x0]))) 283 {*testqi_ext_3} (insn_list:REG_DEP_TRUE
16 (nil))
(nil))
...
(insn 23 22 24 0 (set (reg:QI 68)
(ne:QI (reg:CCZ 17 flags)
(const_int 0 [0x0]))) 480 {*setcc_1} (insn_list:REG_DEP_TRUE 19
(nil))
(expr_list:REG_DEAD (reg:CC 17 flags)
(nil)))
And we should get:
(set (reg:QI 68) (zero_extract:SI (subreg:DI (reg:QI 61 [+5 ]) 0)
(const_int 1 [0x1])
(const_int 0 [0x0])))
because we know that what the compare compares against can only be 1 or 0 as it
is a zero_extract of
size 1.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19331
