Re: Improving reload inheritance code generation and predictability

[Jeff Law <law at redhat dot com>]

On 11/19/10 10:25, Vladimir Makarov wrote:
> That is not about memory increase.  It is about DF data expelling rtl 
> data from caches.
>
> I've just did some measurements of compilation time on your patch on 
> all_cp2k_gfortran.f90 (> 400K lines of fortran)
>
> without patch                                     219.20user
> with only df calls in reload (see patch below)    221.39user
> with all your patch                               221.17user
>
> So 1% of degradation is only because the patch touches DF-data (not 
> scanning insns in finding reload reg as someone can think).  Better 
> inheritance might improve compilation time because less insns are 
> generated (although it is hard to say the difference on two last lines 
> is too small).
Switching to df_insn_rescan_all cuts the cost by about 50%.   I may be 
able to only scan the insns created by caller-save and deal with the 
psuedo->hard reg conversion within mark_spill_regs.  I'll be testing 
that shortly.   Then I'll be looking at Bernd's suggestions (which are a 
rather different approach to the problem).

jeff