https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99068
--- Comment #8 from Segher Boessenkool <segher at gcc dot gnu.org> --- Using update form instructions constrains register allocation and scheduling. It is *not* always a good idea. That is one of the reasons why we currently use update form instructions only when insns just happen to land close (in the same basic block). See auto_inc_dec.c . We also do some work to make it more likely that loops will use these constructs. We don't go out of our way to use update form insns at the cost of everything else. You will see them more often if you use -Os or -O1.
