https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84369
Peter Bergner <bergner at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2018-04-12
CC| |bergner at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #2 from Peter Bergner <bergner at gcc dot gnu.org> ---
Confirmed. Looking at the rtl dumps, the only difference coming into SMS, is
the following (due to combine):
-(insn 25 23 26 4 (set (reg:DI 150 [ iD.2875+-4 ])
- (sign_extend:DI (subreg/v:SI (reg/v:DI 137 [ iD.2875+-4 ]) 4)))
"/home/bergner/gcc/gcc-fsf-mainline-mcpu-native/gcc/testsuite/gcc.dg/sms-10.c":33
38 {extendsidi2}
- (nil))
+(note 25 23 26 4 NOTE_INSN_DELETED)
(insn 26 25 28 4 (set (reg:DI 151)
- (ashift:DI (reg:DI 150 [ iD.2875+-4 ])
- (const_int 3 [0x3])))
"/home/bergner/gcc/gcc-fsf-mainline-mcpu-native/gcc/testsuite/gcc.dg/sms-10.c":33
270 {ashldi3}
- (expr_list:REG_DEAD (reg:DI 150 [ iD.2875+-4 ])
- (nil)))
+ (ashift:DI (sign_extend:DI (subreg:SI (reg/v:DI 137 [ iD.2880+-4 ])
4))
+ (const_int 3 [0x3])))
"/home/bergner/gcc/gcc-fsf-mainline-mcpu-native/gcc/testsuite/gcc.dg/sms-10.c":33
276 {ashdi3_extswsli}
+ (nil))
...and the ashdi3_extswsli pattern is only enabled with power9. Not sure yet
why the above disables SMS, but will keep looking.
