On 08/03/2017 03:02 AM, Jan Hubicka wrote: >> 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 :) I can support that approach :-)
jeff
