[Bug middle-end/114563] ggc_internal_alloc is slow

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114563

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Andi Kleen from comment #6)
> Created attachment 60907 [details]
> patch for multiple free lists in ggc-page
> 
> I saw it in some profile, but later trying didn't help anymore.
> 
> Needs a workload where it matters

PR119387 had

  85.81%       1500713  cc1plus  cc1plus               [.]
ggc_internal_alloc(un

for me.  Can we keep an index to freelist from allocation order to avoid
the linear search?  Other than that the patch looks simple than I thought,
and it definitely resolves an algorithmic complexity issue, so even without
a clear workload where it matters it should be OK (during stage1, that is).