GCC Conversion Status Alan M Jonckheere

12/4/2002A.M.Jonckheere2 Introduction KAI is no longer supported by their new owner, INTEL. Reconstituted C++ Working Group has been investigating alternatives for some time. GCC is the obvious first one to try. Free Reasonably standards compliant and getting better.

12/4/2002A.M.Jonckheere3 Status - CDF CDF has converted all of their code Dedicated a few people for a few weeks. Minor problems, mostly sizes of executables and libraries. RH 7.3 has major problems with a new loader. Much slower, much more memory needed. Not GCC specific. CD has a fix that gets back almost to where the old loader was. GCC still requires 50%+ more memory than KCC to link and is significantly slower. Performance seems to be comparable though I don’t know what’s being done with optimization.

12/4/2002A.M.Jonckheere4 Status – D0 Scott had compiled and built almost all of the D0 code last spring. He had sent the patches to the developers, more than once actually. Developers have been very slow in applying patches. We know that there are no major hurdles. GCC is more “picky” about the standards than KAI. Most problems are real. They can produce bad code.

12/4/2002A.M.Jonckheere5 Status – D0 About a month ago, all the patches were finally applied for fatal errors in the test releases. However, even in the KCC version D0Reco didn’t build. So it was impossible to actually test the results of a build. CSO Decision (8Nov): build p13 using GCC. Paul is authorized to make necessary changes in CVS, both p13 branch and HEAD.

12/4/2002A.M.Jonckheere6 Status – D0 Delays P13 under “rapid” development, many changes Vacations/holidays Going backward Last p13-gcc build had 5-10 problems in addition to those that were still there in the last test release. May be changes that were made in test, didn’t go onto the p13 branch? Need to make a concerted effort.

12/4/2002A.M.Jonckheere7 Immediate This week, Paul will make p13-gcc his highest priority. Should have a D0Reco by the end of the week Need Harry M et al to take a look at it, running their tests as soon as it’s available. This will tell us if GCC is acceptable. No reason to suspect that this won’t be a positive outcome.

12/4/2002A.M.Jonckheere8 Where do we go from here Proposal Turn on warnings Will meld recommendations from Scott and Paul. If there is a conflict, will take it to the CSO meeting. Will report there in any case. Send to developers. STOP doing KCC test releases!!!! Last one this week (or next?) Treat the test releases as prep for p14, which it is. We had already decided that p14 would be GCC if tests were positive. Time to make it so.