Denis Chertykov schrieb:
2011/6/24 Richard Henderson <r...@redhat.com>:
On 06/23/2011 01:15 PM, Denis Chertykov wrote:
text data bss dec hex filename
10032 25 0 10057 2749 bld-avr-orig/gcc/z.o
5816 25 0 5841 16d1 bld-avr-new/gcc/z.o
Richard, can you send me this z.c file ?
Right now I'm notice that new code is worse.
That's gcc.c-torture/compile/950612-1.c.
I have founded that postreload optimizations can't handle results of
new L_R_A code.
I think that it's can be handled by CSE (postreload).
This is a fragment from 950612-1.c:
---------- you can skip it I have a short version below -------
(insn 5186 23 5187 2 (set (reg:HI 30 r30)
(const_int 128 [0x80])) c950612-1.c:20 9 {*movhi}
(nil))
(insn 5187 5186 5189 2 (set (reg:HI 30 r30)
(plus:HI (reg:HI 30 r30)
(reg/f:HI 28 r28))) c950612-1.c:20 21 {*addhi3}
(expr_list:REG_EQUIV (plus:HI (reg/f:HI 28 r28)
(const_int 128 [0x80]))
(nil)))
(insn 5189 5187 2451 2 (set (mem/c:HI (plus:HI (reg:HI 30 r30)
(const_int 1 [0x1])) [8 %sfp+129 S2 A8])
(reg:HI 18 r18)) c950612-1.c:20 9 {*movhi}
(nil))
(note 2451 5189 2537 2 NOTE_INSN_DELETED)
(note 2537 2451 1651 2 NOTE_INSN_DELETED)
(note 1651 2537 3180 2 NOTE_INSN_DELETED)
(note 3180 1651 5191 2 NOTE_INSN_DELETED)
(insn 5191 3180 5192 2 (set (reg:HI 30 r30)
(const_int 128 [0x80])) c950612-1.c:132 9 {*movhi}
(nil))
(insn 5192 5191 5071 2 (set (reg:HI 30 r30)
(plus:HI (reg:HI 30 r30)
(reg/f:HI 28 r28))) c950612-1.c:132 21 {*addhi3}
(expr_list:REG_EQUIV (plus:HI (reg/f:HI 28 r28)
(const_int 128 [0x80]))
(nil)))
(insn 5071 5192 5073 2 (set (mem/c:HI (plus:HI (reg:HI 30 r30)
(const_int 3 [0x3])) [8 %sfp+131 S2 A8])
(reg/v/f:HI 8 r8 [orig:211 pc ] [211])) c950612-1.c:132 9 {*movhi}
(nil))
------------------------------------------------------
Insns 5186,5187 equal to 5191,5192 and 5191,5192 can be removed, but
reload_cse_regs_1 operate only on one insn.
5186 Z=128
5187 Z=Y+128 ; REG_EQUIV Z=Y+128
5189 HI:[Z+1]=HI:R18
...(deleted insns)
5191 Z=128
5192 Z=Y+128 ; REG_EQUIV Z=Y+128
(5191,5192) really a one three addressing add Z=Y+128.
Insns (5191,5192) exists because AVR havn't 3 addressing add.
Insn 5191 destroy REG_EQUIV (it's right), but reload_cse_regs_1 can't
optimize insns 5191,5192.
Did you try to add constraint alternative to *addhi3?
Like "*!d,d,n" or even "*!r,r,n"
I saw some code improvement with that alternative.
Johann
Right now I have only one idea:
1. create peephole2 for joining such insns (5191,5192);
2. inside machine dependent pass rerun postreload and may be gcse2;
3. split joined insns to originals.
Denis.
