http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56484
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-05
11:06:26 UTC ---
Actually, looking more at this, I'd say combiner is innocent here, the problem
is earlier , during ce1 pass, which transforms:
16: ax:SI=call [`output_play'] argc:0
REG_DEAD di:DI
REG_DEAD si:SI
17: r60:SI=ax:SI
REG_DEAD ax:SI
18: flags:CCGOC=cmp(r59:SI,0)
19: pc={(flags:CCGOC>=0)?L21:pc}
REG_DEAD flags:CCGOC
REG_BR_PROB 0x1c84
20: NOTE_INSN_BASIC_BLOCK 4
6: r60:SI=r59:SI
REG_DEAD r59:SI
21: L21:
22: NOTE_INSN_BASIC_BLOCK 5
into:
16: ax:SI=call [`output_play'] argc:0
REG_DEAD di:DI
REG_DEAD si:SI
17: r60:SI=ax:SI
REG_DEAD ax:SI
18: flags:CCGOC=cmp(r59:SI,0)
53: flags:CCGOC=cmp(r59:SI,0)
54: r60:SI={(flags:CCGOC>=0)?ax:SI:r59:SI}
22: NOTE_INSN_BASIC_BLOCK 4
i.e. does what combiner tries to avoid with hard registers. I don't understand
why it can't use r60:SI instead of ax:SI.
