[Bug middle-end/35545] virtual call specialization not happening with FDO

[hubicka at ucw dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35545

--- Comment #10 from Jan Hubicka <hubicka at ucw dot cz> ---
> Tracer depends on the usual estimate_num_insns limits
>  (it is 12 years since I wrote it, so what I recall)

note that one impotant thing that changed in those 12 years is that I
originally carefuly tuned tracer in combination with crossjumping. Tracer
produced duplicates and if no pass managed to take use of them, crossjumping
cleaned them up pre-reload. Trace formation in bb-reorder re-instantiated
duplicated when it seemed sensible for code layout.

This broke, since SSA makes RTL cross jumping quite useless and it is now done
after reg-alloc only.  We never really got working code unification pass on
gimple.
http://www.ucw.cz/~hubicka/papers/amd64/node4.html
Claims that at that time I got 1.6% speedup on SPECint with profile feedback
1.43% code growth.  That is not bad, but wonder to what it translates today.

Honza