------- Comment #4 from hutchinsonandy at gcc dot gnu dot org 2009-11-01 17:24
-------
The problem is still present on 4.3.5 head
I cannot reproduce on 4.5
It looks like reload issue with SUBREG.
Instruction 18 gets reloaded. The output reload is HImode. I will post dump
files but here is extract that appears to highlight problem.
>From lreg dump file:
;; Pred edge 3 [50.0%] (fallthru)
(note 16 15 17 4 [bb 4] NOTE_INSN_BASIC_BLOCK)
(note 17 16 18 4 NOTE_INSN_DELETED)
(insn 18 17 54 4 pr41894.c:29 (set (subreg:QI (reg/v:HI 43 [ tmp ]) 0)
(plus:QI (reg:QI 42 [ D.1188 ])
(const_int -1 [0xffffffff]))) 15 {addqi3} (expr_list:REG_DEAD
(reg:QI 42 [ D.1188 ])
(nil)))
(jump_insn 54 18 55 4 (set (pc)
(label_ref 26)) 101 {jump} (nil))
;; End of basic block 4 -> ( 6)
;; lr out 28 [r28] 32 [__SP_L__] 34 [argL] 43
;; live out 28 [r28] 32 [__SP_L__] 34 [argL] 43
from greg dump file:
Spilling for insn 18.
Using reg 18 for reload 0
Spilling for insn 18.
Using reg 18 for reload 0
Reloads for insn # 18
Reload 0: reload_in (QI) = (reg:QI 24 r24 [orig:42 D.1188 ] [42])
reload_out (HI) = (reg/v:HI 28 r28 [orig:43 tmp ] [43])
LD_REGS, RELOAD_OTHER (opnum = 0)
reload_in_reg: (reg:QI 24 r24 [orig:42 D.1188 ] [42])
reload_out_reg: (reg/v:HI 28 r28 [orig:43 tmp ] [43])
reload_reg_rtx: (reg:HI 18 r18)
deleting insn with uid = 2.
;; Register dispositions:
42 in 24 43 in 28 44 in 24
;; Hard regs used: 18 19 24 25 28 29 32
Giving
(insn 57 17 18 4 pr41894.c:29 (set (reg:QI 18 r18)
(reg:QI 24 r24 [orig:42 D.1188 ] [42])) 4 {*movqi} (nil))
(insn 18 57 58 4 pr41894.c:29 (set (reg:QI 18 r18)
(plus:QI (reg:QI 18 r18)
(const_int -1 [0xffffffff]))) 15 {addqi3} (nil))
(insn 58 18 54 4 pr41894.c:29 (set (reg/v:HI 28 r28 [orig:43 tmp ] [43])
(reg:HI 18 r18)) 8 {*movhi} (nil))
(jump_insn 54 58 55 4 (set (pc)
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41894
