[Bug rtl-optimization/18233] extraneous inc/dec pair

[pinskia at gcc dot gnu dot org]

--- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-11 
20:15 ---
Confirmed.  We are splitting ffs late which causes this problem (maybe doing an 
expand instead of 
splitter fixes the problem).

-- 
   What|Removed |Added

 Status|UNCONFIRMED |NEW
 Ever Confirmed||1
   Last reconfirmed|-00-00 00:00:00 |2004-11-11 20:15:49
   date||


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18233

[Bug rtl-optimization/18233] extraneous inc/dec pair

[pinskia at gcc dot gnu dot org]

--- Additional Comments From pinskia at gcc dot gnu dot org  2004-10-30 19:28 
---
On PPC, we get:
cmpwi cr0,r3,0
li r2,0
neg r0,r3
and r0,r3,r0
bne- cr0,L7
mr r3,r2
blr
L7:
cntlzw r0,r0
subfic r2,r0,31
mr r3,r2
blr
which is good and there is no extra subfic and also ffs has definition to return 0 for 
0 so the extran 
subtraction on the ffs causes this to be good code on PPC.

-- 
   What|Removed |Added

   Severity|normal  |enhancement
  Component|tree-optimization   |rtl-optimization
   Keywords||missed-optimization


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18233