On Wed, Mar 7, 2012 at 11:52 AM, Richard Sandiford <rdsandif...@googlemail.com> wrote: > Richard Guenther <richard.guent...@gmail.com> writes: >> On Wed, Mar 7, 2012 at 11:11 AM, Richard Sandiford >> <rdsandif...@googlemail.com> wrote: >>> Jakub Jelinek <ja...@redhat.com> writes: >>>> On Wed, Mar 07, 2012 at 09:52:51AM +0000, Richard Sandiford wrote: >>>>> This patch restores x86_64-linux-gnu bootstrap after my patch for 52372. >>>>> Applied as obvious. >>>>> >>>>> Sorry for the breakage. >>>> >>>> Was it really necessary to move these out of the global rtx array? >>>> Now you completely unnecessarily have 4 new GTY roots with all the overhead >>>> it has. Wouldn't just moving their initialization elsewhere be sufficient? >>> >>> It had to be outside the "global" array, because that's a per-target thing. >>> E.g. MIPS16 and non-MIPS16 have separate target_rtl structures, but ought >>> to have the same pc_rtx (just as they ought to have the same const0_rtx, >>> etc.) >>> >>> I hadn't realised that the overhead of 4 roots was much greater than the >>> overhead of one root pointing to a 4-element array. We could have a new >>> 4-element array if that's a problem. >> >> Why can't you put the same RTXen in the per-target rtl structures? > > But where does it stop? Do we move const_tiny_rtx to the target > structure too? > > Logically, the target structure should be for target-specific rtl. > Target-independent rtl like constants, (cc0), (pc), etc., should be > shared between targets. It seems a shame if GC inefficiencies > force us to use a different scheme.
Ok, if we know for certain this rtl will be never target specific (consider a gcc for multiple targets, sparc and x86_64 for example), then we should have a single structure that contains all those global rtxen. Richard. > Richard
