https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96201
Hongtao.liu <crazylht at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |crazylht at gmail dot com
--- Comment #1 from Hongtao.liu <crazylht at gmail dot com> ---
The issue is caused by pass_ivopt, ivopt select only one iv for f3(dn) which
seems not to be optimal, and select two iv for f4(sn,dn) which seems optimal.
---
loop in f3:
Selected IV set for loop 1 at pr96201.c:25, 10 avg niters, 1 IVs:
Candidate 8:
Var befor: dn_24
Var after: dn_18
Incr POS: orig biv
IV struct:
Type: int *
Base: (int *) _3
Step: 4
Biv: N
Overflowness wrto loop niter: Overflow
loop in f4:
Selected IV set for loop 1 at pr96201.c:34, 10 avg niters, 2 IVs:
Candidate 6:
Var befor: sn_26
Var after: sn_20
Incr POS: orig biv
IV struct:
Type: int *
Base: sn_14
Step: 4
Object: (void *) sn_14
Biv: N
Overflowness wrto loop niter: Overflow
Candidate 8:
Var befor: dn_27
Var after: dn_21
Incr POS: orig biv
IV struct:
Type: int *
Base: dn_16
Step: 4
Object: (void *) dn_16
Biv: N
Overflowness wrto loop niter: Overflow
---
then it generate more instructions for f3 which pass_combine failed to combine
them.
---
loop in f3:
Trying 19 -> 22:
19: r83:DI=r92:DI
22: [r83:DI]=r89:SI
REG_DEAD r89:SI
REG_DEAD r83:DI
Can't combine i2 into i3
Trying 21 -> 22:
21: r89:SI=[r93:DI]
REG_DEAD r93:DI
22: [r83:DI]=r89:SI
REG_DEAD r89:SI
REG_DEAD r83:DI
Failed to match this instruction:
(set (mem:SI (reg/v/f:DI 83 [ dn ]) [1 *dn_2+0 S4 A32])
(mem:SI (reg/f:DI 93 [ _20 ]) [1 *_20+0 S4 A32]))
Trying 18, 21 -> 22:
18: {r93:DI=r92:DI+r102:DI;clobber flags:CC;}
REG_UNUSED flags:CC
21: r89:SI=[r93:DI]
REG_DEAD r93:DI
22: [r83:DI]=r89:SI
REG_DEAD r89:SI
REG_DEAD r83:DI
Can't combine i1 into i3
Trying 21, 19 -> 22:
21: r89:SI=[r93:DI]
REG_DEAD r93:DI
19: r83:DI=r92:DI
22: [r83:DI]=r89:SI
REG_DEAD r89:SI
REG_DEAD r83:DI
Can't combine i1 into i3
(insn 18 16 19 4 (parallel [
(set (reg/f:DI 93 [ _20 ])
(plus:DI (reg/v/f:DI 92 [ dn ])
(reg:DI 102)))
(clobber (reg:CC 17 flags))
]) 210 {*adddi_1}
(expr_list:REG_UNUSED (reg:CC 17 flags)
(nil)))
(insn 19 18 20 4 (set (reg/v/f:DI 83 [ dn ])
(reg/v/f:DI 92 [ dn ])) 74 {*movdi_internal}
(nil))
(insn 20 19 21 4 (parallel [
(set (reg/v/f:DI 92 [ dn ])
(plus:DI (reg/v/f:DI 92 [ dn ])
(const_int 4 [0x4])))
(clobber (reg:CC 17 flags))
]) "pr96201.c":25:24 210 {*adddi_1}
(expr_list:REG_UNUSED (reg:CC 17 flags)
(nil)))
(insn 21 20 22 4 (set (reg:SI 89 [ _9 ])
(mem:SI (reg/f:DI 93 [ _20 ]) [1 *_20+0 S4 A32])) "pr96201.c":25:29 75
{*movsi_internal}
(expr_list:REG_DEAD (reg/f:DI 93 [ _20 ])
(nil)))
(insn 22 21 24 4 (set (mem:SI (reg/v/f:DI 83 [ dn ]) [1 *dn_2+0 S4 A32])
(reg:SI 89 [ _9 ])) "pr96201.c":25:27 75 {*movsi_internal}
(expr_list:REG_DEAD (reg:SI 89 [ _9 ])
(expr_list:REG_DEAD (reg/v/f:DI 83 [ dn ])
(nil))))
loop in f4:
Trying 16, 18, 17 -> 19:
16: {r89:DI=r89:DI+0x4;clobber flags:CC;}
REG_UNUSED flags:CC
18: r88:SI=[r89:DI-0x4]
17: {r90:DI=r90:DI+0x4;clobber flags:CC;}
REG_UNUSED flags:CC
19: [r90:DI-0x4]=r88:SI
REG_DEAD r88:SI
Successfully matched this instruction:
(parallel [
(set (mem:SI (reg/v/f:DI 90 [ dn ]) [1 MEM[base: dn_21, offset: -4B]+0
S4 A32])
(mem:SI (reg/v/f:DI 89 [ sn ]) [1 MEM[base: sn_20, offset: -4B]+0
S4 A32]))
(set (reg/v/f:DI 90 [ dn ])
(plus:DI (reg/v/f:DI 90 [ dn ])
(const_int 4 [0x4])))
(set (reg/v/f:DI 89 [ sn ])
(plus:DI (reg/v/f:DI 89 [ sn ])
(const_int 4 [0x4])))
])
(insn 16 15 17 3 (parallel [
(set (reg/v/f:DI 89 [ sn ])
(plus:DI (reg/v/f:DI 89 [ sn ])
(const_int 4 [0x4])))
(clobber (reg:CC 17 flags))
]) "pr96201.c":34:32 210 {*adddi_1}
(expr_list:REG_UNUSED (reg:CC 17 flags)
(nil)))
(insn 17 16 18 3 (parallel [
(set (reg/v/f:DI 90 [ dn ])
(plus:DI (reg/v/f:DI 90 [ dn ])
(const_int 4 [0x4])))
(clobber (reg:CC 17 flags))
]) "pr96201.c":34:24 210 {*adddi_1}
(expr_list:REG_UNUSED (reg:CC 17 flags)
(nil)))
(insn 18 17 19 3 (set (reg:SI 88 [ _9 ])
(mem:SI (plus:DI (reg/v/f:DI 89 [ sn ])
(const_int -4 [0xfffffffffffffffc])) [1 MEM[base: sn_20,
offset: -4B]+0 S4 A32])) "pr96201.c":34:29 75 {*movsi_internal}
(nil))
(insn 19 18 21 3 (set (mem:SI (plus:DI (reg/v/f:DI 90 [ dn ])
(const_int -4 [0xfffffffffffffffc])) [1 MEM[base: dn_21,
offset: -4B]+0 S4 A32])
(reg:SI 88 [ _9 ])) "pr96201.c":34:27 75 {*movsi_internal}
(expr_list:REG_DEAD (reg:SI 88 [ _9 ])
(nil)))
---
