On Wed, Jul 1, 2015 at 11:39 AM, Trevor Saunders <tbsau...@tbsaunde.org> wrote: > On Tue, Jun 23, 2015 at 07:41:42PM +0100, Richard Sandiford wrote: >> [A fair bit later than promised, sorry...] >> >> Mikhail posted a patch to make genflags generate the default HAVE_foo >> and gen_foo definitions that have recently been added to defaults.h: >> >> https://gcc.gnu.org/ml/gcc-patches/2015-06/msg00723.html >> >> I agree it'd be a good idea to generate this kind of thing automatically, >> but I think we should take the opportunity to move the interface to the >> target structure. I.e.: >> >> HAVE_foo -> targetm.have_foo () >> gen_foo -> targetm.gen_foo () >> >> This should move us closer to the pipedream goal of supporting multiple >> targets at once. It should also mean that only the target code depends >> on insn-flags.h. > > using targetm. certainly seems like an improvement. I wonder if it > would be faster to stick this data on a per function object. I think > that would mean you could compute what insns are available once when the > function is created and afterwards all checks would only needed to be > reading computed values.
I think the memory cost of this is prohibitive. Richard. > Trev >
