------- Additional Comments From dann at godzilla dot ics dot uci dot edu
2005-08-03 18:21 -------
These insns in the .32.flow2 RTL dump:
(insn:HI 12 7 14 0 (set (mem/s:SI (plus:SI (reg/v/f:SI 0 ax [orig:58 screen ]
[58])
(const_int 3144 [0xc48])) [7 <variable>.selection_count+0 S4
A32])
(const_int 0 [0x0])) 34 {*movsi_1} (insn_list:REG_DEP_TRUE 6 (nil))
(nil))
(insn:HI 14 12 15 0 (set (mem/s:SI (plus:SI (reg/v/f:SI 0 ax [orig:58 screen ]
[58])
(const_int 3124 [0xc34])) [7 <variable>.startHCol+0 S4 A32])
(const_int 0 [0x0])) 34 {*movsi_1} (nil)
(nil))
(insn:HI 15 14 17 0 (set (mem/s:SI (plus:SI (reg/v/f:SI 0 ax [orig:58 screen ]
[58])
(const_int 3120 [0xc30])) [7 <variable>.startHRow+0 S4 A32])
(const_int 0 [0x0])) 34 {*movsi_1} (nil)
(nil))
[snip]
are transformed by this peephole2:
(define_peephole2
[(match_scratch:SI 1 "r")
(set (match_operand:SI 0 "memory_operand" "")
(const_int 0))]
"! optimize_size
&& ! TARGET_USE_MOV0
&& TARGET_SPLIT_LONG_MOVES
&& get_attr_length (insn) >= ix86_cost->large_insn
&& peep2_regno_dead_p (0, FLAGS_REG)"
[(parallel [(set (match_dup 1) (const_int 0))
(clobber (reg:CC FLAGS_REG))])
(set (match_dup 0) (match_dup 1))]
"")
into:
(insn 46 45 43 0 (set (mem/s:SI (plus:SI (reg/v/f:SI 0 ax [orig:58 screen ]
[58])
(const_int 3144 [0xc48])) [7 <variable>.selection_count+0 S4
A32])
(reg:SI 1 dx)) -1 (nil)
(expr_list:REG_DEAD (reg:SI 1 dx)
(nil)))
(insn 43 46 44 0 (parallel [
(set (reg:SI 2 cx)
(const_int 0 [0x0]))
(clobber (reg:CC 17 flags))
]) -1 (nil)
(expr_list:REG_UNUSED (reg:CC 17 flags)
(nil)))
(insn 44 43 41 0 (set (mem/s:SI (plus:SI (reg/v/f:SI 0 ax [orig:58 screen ]
[58])
(const_int 3124 [0xc34])) [7 <variable>.startHCol+0 S4 A32])
(reg:SI 2 cx)) -1 (nil)
(expr_list:REG_DEAD (reg:SI 2 cx)
(nil)))
(insn 41 44 42 0 (parallel [
(set (reg:SI 1 dx)
(const_int 0 [0x0]))
(clobber (reg:CC 17 flags))
]) -1 (nil)
(expr_list:REG_UNUSED (reg:CC 17 flags)
(nil)))
(insn 42 41 39 0 (set (mem/s:SI (plus:SI (reg/v/f:SI 0 ax [orig:58 screen ]
[58])
(const_int 3120 [0xc30])) [7 <variable>.startHRow+0 S4 A32])
(reg:SI 1 dx)) -1 (nil)
(expr_list:REG_DEAD (reg:SI 1 dx)
(nil)))
(insn 39 42 40 0 (parallel [
(set (reg:SI 2 cx)
(const_int 0 [0x0]))
(clobber (reg:CC 17 flags))
]) -1 (nil)
(expr_list:REG_UNUSED (reg:CC 17 flags)
(nil)))
[snip]
Can the result of a peephole2 be used in matching another peephole2?
If yes in that case another peephole2 can be written to match
(set REGXXX 0) ;; this is generated by a previous peephole2
(set (mem.... ) (const_int 0))
and change that to
(set (mem ....) REGXXXX)
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23102
