Jakub Jelinek <ja...@redhat.com> writes: > On Wed, Nov 13, 2013 at 11:27:10AM +0100, Richard Biener wrote: >> > Also, I wonder if we couldn't defer the expensive ira_init, if the info >> > computed by it is used only during RTL optimization passes (haven't >> > verified >> > it yet), then supposedly we could just remember using some target hook >> > what the last state was when we did ira_init last time, and call ira_init >> > again at the start of expansion or so if it is different from the last >> > time. >> > For i?86/x86_64/ppc* this would be whether the current function's >> > DECL_FUNCTION_SPECIFIC_TARGET is the same as one for which ira_init has >> > been >> > called, for rx whether interrupt attribute is the same and for mips >> > whatever >> > is needed. >> >> I wonder why we cannot move all the stuff we re-init to a member >> of struct function (or rather have a pointer to that info there >> to cache it across functions with the same options). That is, >> get rid of more global state? That would make switching back >> and forth cheaper. > > Isn't that what the SWITCHABLE_TARGET stuff is all about? > So, perhaps we should just define SWITCHABLE_TARGET on i?86/x86_64/powerpc* > (and rx if maintainer cares) and tweak it to attach somehow > struct target_globals * to TARGET_OPTION_NODE somehow. > A problem might be that lots of the save_target_globals > allocated structures are heap allocated rather than GC, so we might leak > memory. Wonder if save_target_globals couldn't just compute the > aggregate size of all the structures it allocates with XCNEW right now > (plus required alignment if needed) and just allocate them together > with the ggc_alloc_target_globals after the target_globals structure > itself.
Yeah, that might be worth doing. I think the only non-GCed structures with subpointers are target_ira_int and target_lra_int, but we could probably convert them to GCed structures. (And perhaps use the same technique recursively. E.g. LRA could work out the maximum number of operand_alternative structures needed and allocate them in one go.) Thanks, Richard
