> On 08/02/2017 01:51 PM, Richard Biener wrote: > > On Wed, Aug 2, 2017 at 1:20 PM, Martin Liška <mli...@suse.cz> wrote: > >> Hello. > >> > >> After some discussions with Honza, I've decided to convert current code in > >> stmt.c that > >> is responsible for switch expansion. More precisely, I would like to > >> convert the code > >> to expand gswitch statements on tree level. Currently the newly created > >> pass is executed > >> at the end of tree optimizations. > >> > >> My plan for future is to inspire in [1] and come up with some more > >> sophisticated switch > >> expansions. For that I've been working on a paper where I'll summarize > >> statistics based > >> on what I've collected in openSUSE distribution with specially > >> instrumented GCC. If I'll be > >> happy I can also fit in to schedule of this year's Cauldron with a talk. > >> > >> Patch can bootstrap on ppc64le-redhat-linux and survives regression tests. > >> > >> Thoughts? > > > > First of all thanks. > > > > I think part of switch expansion moved to switch-conversion some time ago > > (emit_case_bit_tests). So maybe the full lowering should be in at least > > the same source file and it should maybe applied earlier for a subset of > > cases (very low number of cases for example). > > Yep, good idea. I'll take a look. > > > > > Did you base the code on the RTL expansion code or did you re-write it from > > scratch? > > It's based, I've just changed the function that create CFG.
I have talked Martin to do this in first step. Switch expansion is infinitely difficult problem and I think changing representation first and keeping the basic algorithm is easiest way to get something done. Algorithm will be improved next as far as I know :) Honza > > Martin
