Well, differences of opinion is what makes horse races. Reed On 06/04/2012 04:57 PM, Daniel Berlin wrote:> On Mon, Jun 4, 2012 at 7:53 PM, reed kotler<rkotler at mips.com> wrote: >> On 06/04/2012 03:25 PM, Daniel Berlin wrote: >>> I'm pretty sure neither llvm nor clang have any technical debt at all. >>> >>> On Mon, Jun 4, 2012 at 5:18 PM, reed kotler<rkotler at mips.com> wrote: >>>> something to think about as llvm and clang grows. >>>> >>>> http://en.wikipedia.org/wiki/Technical_debt >>>> _______________________________________________ >>>> LLVM Developers mailing list >>>> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu >>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >> I hope you are joking. >> > Why would I be joking? > >> It's not meant as a criticism of llvm or clang but there is already an >> enormous amount >> of technical debt. > I don't see that. > >> It's something to try and get a handle on before it gets out of hand. > The consequences will never be the same >> Documentation is one area where it is accumulating fast but there are >> others. > I think LLVM is incredibly well documented >> Testing is another area. > It also has at least 10-15 tests. >> Tablegen alone has huge technical debt. > I'm sorry you feel that way. >> To me, there should be a cap placed on the number of lines of code in llvm. > Will there be a credit offset system? >> Like a budget. We should try and rewrite and refactor to keep the number of >> lines from growing >> without bound. >> >> At this point lots of patterns should be developing where other tools (like >> tablegen) could be >> written to reduce the amount of code and make things more understandable. > I agree. We should macroize most of the passes so they aren't so wordy. > >> Reed >>
Can we get back to the substantive discussion about your ideas for lessening the technical debt? On Mon, Jun 4, 2012 at 8:05 PM, reed kotler <rkotler at mips.com> wrote:> Well, differences of opinion is what makes horse races. > > Reed > > > On 06/04/2012 04:57 PM, Daniel Berlin wrote: >> >> On Mon, Jun 4, 2012 at 7:53 PM, reed kotler<rkotler at mips.com> wrote: >>> >>> On 06/04/2012 03:25 PM, Daniel Berlin wrote: >>>> >>>> I'm pretty sure neither llvm nor clang have any technical debt at all. >>>> >>>> On Mon, Jun 4, 2012 at 5:18 PM, reed kotler<rkotler at mips.com> wrote: >>>>> >>>>> something to think about as llvm and clang grows. >>>>> >>>>> http://en.wikipedia.org/wiki/Technical_debt >>>>> _______________________________________________ >>>>> LLVM Developers mailing list >>>>> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu >>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >>> >>> I hope you are joking. >>> >> Why would I be joking? >> >>> It's not meant as a criticism of llvm or clang but there is already an >>> enormous amount >>> of technical debt. >> >> I don't see that. >> >>> It's something to try and get a handle on before it gets out of hand. >> >> The consequences will never be the same >>> >>> Documentation is one area where it is accumulating fast but there are >>> others. >> >> I think LLVM is incredibly well documented >>> >>> Testing is another area. >> >> It also has at least 10-15 tests. >>> >>> Tablegen alone has huge technical debt. >> >> I'm sorry you feel that way. >>> >>> To me, there should be a cap placed on the number of lines of code in >>> llvm. >> >> Will there be a credit offset system? >>> >>> Like a budget. We should try and rewrite and refactor to keep the number >>> of >>> lines from growing >>> without bound. >>> >>> At this point lots of patterns should be developing where other tools >>> (like >>> tablegen) could be >>> written to reduce the amount of code and make things more understandable. >> >> I agree. We should macroize most of the passes so they aren't so wordy. >> >>> Reed >>> >
On 06/04/2012 05:17 PM, Daniel Berlin wrote:> Can we get back to the substantive discussion about your ideas for > lessening the technical debt?The lessening requires enlisting people that are willing to do this as opposed to doing fun science like cool optimization. I,for example, find the documentaiton, cleanup and refactoring to be interesting so I don't feel cheated to work on it as opposed to implementing some new fangled register allocator. For example, there is almost no documentation on all the application specific plugins for tablegen. There are some tablegen files and some small comments here and there and you can guess some of it from just knowing about compilers but it's nothing close to what could be called documentation. I've started on my own to try and further document tablegen. I gave a talk/tutorial at LLVM Europe on the general tablegen language and it was well received. Even people that had worked with it for a while said they took away things they never understood about it. It was clear when I studied tablegen that there are many serious problems with it from a language point of view and from a tool point view. Those things would all need to be cleared up before some bigger form of it that could go beyond just laying out data structures could be developed. If there is sufficient interest, I think that maybe a separate discussion list to deal with technical debt would make sense. I think for a lot of people it would be uninteresting to get all those extra posts. It's a question of enlisting people that want to work on it and convincing people that are not interested to work on it that it's something important to do and to welcome the help and not obstruct the effort. So far I have created some google code projects for various things I'm interested to work on. I've created separate google code projects because I don't have the bandwidth to work on this if there is resistance to it. So in my google code areas, I can do what I want without a big discussion on every step. So maybe only my team will use it and then it can just sit in google code forever. So there is a cutting edge of the llvm/clang project which will never want to wait for all the technical debt to get paid. This is a natural thing. You can't more forward trying to make everything be A+ quality; you can only do the A+ work after some reflection and experience with a given problem and rewriting and refactoring it many times. But at the same time, the technical debt needs to be settled or it will get out of hand and unpayable in the future. Reed> On Mon, Jun 4, 2012 at 8:05 PM, reed kotler<rkotler at mips.com> wrote: >> Well, differences of opinion is what makes horse races. >> >> Reed >> >> >> On 06/04/2012 04:57 PM, Daniel Berlin wrote: >>> On Mon, Jun 4, 2012 at 7:53 PM, reed kotler<rkotler at mips.com> wrote: >>>> On 06/04/2012 03:25 PM, Daniel Berlin wrote: >>>>> I'm pretty sure neither llvm nor clang have any technical debt at all. >>>>> >>>>> On Mon, Jun 4, 2012 at 5:18 PM, reed kotler<rkotler at mips.com> wrote: >>>>>> something to think about as llvm and clang grows. >>>>>> >>>>>> http://en.wikipedia.org/wiki/Technical_debt >>>>>> _______________________________________________ >>>>>> LLVM Developers mailing list >>>>>> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu >>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >>>> I hope you are joking. >>>> >>> Why would I be joking? >>> >>>> It's not meant as a criticism of llvm or clang but there is already an >>>> enormous amount >>>> of technical debt. >>> I don't see that. >>> >>>> It's something to try and get a handle on before it gets out of hand. >>> The consequences will never be the same >>>> Documentation is one area where it is accumulating fast but there are >>>> others. >>> I think LLVM is incredibly well documented >>>> Testing is another area. >>> It also has at least 10-15 tests. >>>> Tablegen alone has huge technical debt. >>> I'm sorry you feel that way. >>>> To me, there should be a cap placed on the number of lines of code in >>>> llvm. >>> Will there be a credit offset system? >>>> Like a budget. We should try and rewrite and refactor to keep the number >>>> of >>>> lines from growing >>>> without bound. >>>> >>>> At this point lots of patterns should be developing where other tools >>>> (like >>>> tablegen) could be >>>> written to reduce the amount of code and make things more understandable. >>> I agree. We should macroize most of the passes so they aren't so wordy. >>> >>>> Reed >>>>
We already have a list of technical debt, just look at bugzilla (code-cleanup). There has been many refactoring efforts, e.g. one major was to MC by Evan Cheng last year. Before the refactoring was done, it was clearly a technical debt, because the refactoring only fixed violations of the design. Dan Gohman has been pointing out some design debt about the LLVM IR. In general, it is very easy to become used to bad living conditions because the are seen as "natural" and people generally try to be happy with what they have. Code tend to slowly get worse without anyone taking much notice, people are busy, and the code looks good enough. Lack of understanding of the design and not knowing the better way of doing something is often a cause of adding to the technical debt. I don't know if there is an easy way to lessen technical debt, other than to think more and type less, which might not be in a developers mind when a deadline is close. One thing that might help would be to write a couple more lines for code reviews, and explain why things are the way they are, and if they can't be easily explained something else should be done e.g. documentation or refactoring to make the code simpler (add to bugzilla if it can't be done at the time). - Jan>________________________________ > From: Daniel Berlin <dberlin at dberlin.org> >To: reed kotler <rkotler at mips.com> >Cc: "llvmdev at cs.uiuc.edu" <llvmdev at cs.uiuc.edu> >Sent: Monday, June 4, 2012 8:17 PM >Subject: Re: [LLVMdev] technical debt > >Can we get back to the substantive discussion about your ideas for >lessening the technical debt? > >On Mon, Jun 4, 2012 at 8:05 PM, reed kotler <rkotler at mips.com> wrote: >> Well, differences of opinion is what makes horse races. >> >> Reed >> >> >> On 06/04/2012 04:57 PM, Daniel Berlin wrote: >>> >>> On Mon, Jun 4, 2012 at 7:53 PM, reed kotler<rkotler at mips.com> wrote: >>>> >>>> On 06/04/2012 03:25 PM, Daniel Berlin wrote: >>>>> >>>>> I'm pretty sure neither llvm nor clang have any technical debt at all. >>>>> >>>>> On Mon, Jun 4, 2012 at 5:18 PM, reed kotler<rkotler at mips.com> wrote: >>>>>> >>>>>> something to think about as llvm and clang grows. >>>>>> >>>>>> http://en.wikipedia.org/wiki/Technical_debt >>>>>> _______________________________________________ >>>>>> LLVM Developers mailing list >>>>>> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu >>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >>>> >>>> I hope you are joking. >>>> >>> Why would I be joking? >>> >>>> It's not meant as a criticism of llvm or clang but there is already an >>>> enormous amount >>>> of technical debt. >>> >>> I don't see that. >>> >>>> It's something to try and get a handle on before it gets out of hand. >>> >>> The consequences will never be the same >>>> >>>> Documentation is one area where it is accumulating fast but there are >>>> others. >>> >>> I think LLVM is incredibly well documented >>>> >>>> Testing is another area. >>> >>> It also has at least 10-15 tests. >>>> >>>> Tablegen alone has huge technical debt. >>> >>> I'm sorry you feel that way. >>>> >>>> To me, there should be a cap placed on the number of lines of code in >>>> llvm. >>> >>> Will there be a credit offset system? >>>> >>>> Like a budget. We should try and rewrite and refactor to keep the number >>>> of >>>> lines from growing >>>> without bound. >>>> >>>> At this point lots of patterns should be developing where other tools >>>> (like >>>> tablegen) could be >>>> written to reduce the amount of code and make things more understandable. >>> >>> I agree. We should macroize most of the passes so they aren't so wordy. >>> >>>> Reed >>>> >> > >_______________________________________________ >LLVM Developers mailing list >LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu >http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev > > >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20120607/e64cbcfd/attachment.html>