Hi. I see that to detect scops firstly we search for regions in CFG ( by RegionInfo ) and then select regions that answer some requirements ( in ScopDetection ). Because only affine expressions in conditions and bounds are permissible, we trying to get scalar expressions into affine form by AffineSCEVIterator. At present there plugs for scev types Truncate, ZeroExtend, SignExtend, UDivExpr, UMaxExpr , SMaxExpr. Also there are no support for wrap flags NUW, NSW, NW. It can be unsafe if we doesn't provide this information in polly IR. So I will mainly improve AffineSCEVIterator. Now I should to show test cases indicating that - loops with above-listed types expressions cannot be converted to the polyhedral representation - wrap flags are ignored and this can bring to broken programs (in fact, here I need some clarification) Do I understand correctly? I have some QA skills. Is Polly in need of autoconf, cmake, buildbot setting up? Maybe this will be my tasks for first weeks 5 апреля 2011 г. 16:39 пользователь Tobias Grosser <grosser at fim.uni-passau.de> написал:> On 04/04/2011 12:23 AM, Vlad Krylov wrote: >> >> Hi. > > Hi Vlad, > > first of all it seems the conflict with raghesh was already solved. Nice. > > Regarding your draft. It looks like a reasonable first version, but it > obviously needs to be extended for the final application. I would also > recommend to install Polly and try to find the first test cases that cannot > be handled. > > Some comments to your work plan: > >> My plan would be: >> >> 1w Study sources of Polly and LLVM docs relating to analysis > > You should do this for your application. ;-) At least you should start. Did > you already find the place in the scopdetection where we check if an access > function is valid? > >> 2w Create tests which demonstrate problems with NSW/NUW > > I think it would be good to show at least one test case already in the > application. > >> 3-4w Fix the handling of wrap overflows. > > What does need to be fixed? What is wrong at the moment? (there is obviously > a problem as stated on the Polly wiki, but I believe it would be good to > explain this to the audience. It will also be good for you to understand the > actual problem in the code (In case you need help feel free to ask)). > >> 5w Complete middle term paperwork. > > What is middle term paperwork? > >> 6w Create tests for each of cases which are not currently optimized >> (e.g. have min/max, sext/zext, trunc or unsigned comparisons in the loop >> bounds or memory accesses). > > Again. Some test cases could already be shown in the application. > >> 7w Learn how optimization process work for this examples. > > I do not think you need to optimize here anything. It should be sufficient > to recognize code that includes such statements and transform them into a > polyhedral represenation. Optimizers like Pluto will automatically calculate > the relevant optimizations, if you generate a correct polyhedral > representation. > >> 8-10w Enable tests one by one. > > By 'Enable tests' do you mean implementing support for min/max .. > expressions? > >> 11w Estimate SPEC 264ref performnace improvement (yes, I have access to >> one). > > What do you plan to measure exactly? Runtime performance? > > I think another very interesting thing would be an analysis that shows how > much of the hot loops we can optimize. You can use such an analysis also to > estimate the possible speedups we can achieve. Andreas (CCed) may be able to > help you with some performance measurements he has already taken. > >> 12w Complete paperwork. > > What is paperwork? And why does is take a week? > > I also think it would be great if you could keep track of the code coverage > improvement you achieve on the llvm testsuite. > > I added a lot of remarks, mainly because I am really interested in such a > project. Please feel free to ask back if you need any help. > > Cheers > Tobi >
Hi, 2011/4/8 Vlad Krylov <krvladislav at gmail.com>:> Hi. > > I see that to detect scops firstly we search for regions in CFG ( by > RegionInfo ) and then select regions that answer some requirements ( > in ScopDetection ). Because only affine expressions in conditions and > bounds are permissible, we trying to get scalar expressions into > affine form by AffineSCEVIterator. At present there plugs for scev > types Truncate, ZeroExtend, SignExtend, UDivExpr, UMaxExpr , SMaxExpr. > Also there are no support for wrap flags NUW, NSW, NW. It can be > unsafe if we doesn't provide this information in polly IR.Yes, if AffineSCEVIterator can iterate Truncate, ZeroExtend and SignExtend correctly, polly can accept much more Scops.> > So I will mainly improve AffineSCEVIterator. Now I should to show test > cases indicating that > - loops with above-listed types expressions cannot be converted to the > polyhedral representation > - wrap flags are ignored and this can bring to broken programs (in > fact, here I need some clarification) > > Do I understand correctly?I think so.> > I have some QA skills. Is Polly in need of autoconf, cmake, buildbot > setting up? Maybe this will be my tasks for first weeksLooking forward to working with you :) best regards ether
How to feed pocc by jscop files which are made with -polly-export-jscop? 2011/4/8 ether zhhb <etherzhhb at gmail.com>:> Hi, > > 2011/4/8 Vlad Krylov <krvladislav at gmail.com>: >> Hi. >> >> I see that to detect scops firstly we search for regions in CFG ( by >> RegionInfo ) and then select regions that answer some requirements ( >> in ScopDetection ). Because only affine expressions in conditions and >> bounds are permissible, we trying to get scalar expressions into >> affine form by AffineSCEVIterator. At present there plugs for scev >> types Truncate, ZeroExtend, SignExtend, UDivExpr, UMaxExpr , SMaxExpr. >> Also there are no support for wrap flags NUW, NSW, NW. It can be >> unsafe if we doesn't provide this information in polly IR. > Yes, if AffineSCEVIterator can iterate Truncate, ZeroExtend and > SignExtend correctly, polly can accept much more Scops. >> >> So I will mainly improve AffineSCEVIterator. Now I should to show test >> cases indicating that >> - loops with above-listed types expressions cannot be converted to the >> polyhedral representation >> - wrap flags are ignored and this can bring to broken programs (in >> fact, here I need some clarification) >> >> Do I understand correctly? > I think so. >> >> I have some QA skills. Is Polly in need of autoconf, cmake, buildbot >> setting up? Maybe this will be my tasks for first weeks > Looking forward to working with you :) > > best regards > ether >
2011/4/8 ether zhhb <etherzhhb at gmail.com>:> Hi, > > 2011/4/8 Vlad Krylov <krvladislav at gmail.com>: >> Hi. >> >> I see that to detect scops firstly we search for regions in CFG ( by >> RegionInfo ) and then select regions that answer some requirements ( >> in ScopDetection ). Because only affine expressions in conditions and >> bounds are permissible, we trying to get scalar expressions into >> affine form by AffineSCEVIterator. At present there plugs for scev >> types Truncate, ZeroExtend, SignExtend, UDivExpr, UMaxExpr , SMaxExpr. >> Also there are no support for wrap flags NUW, NSW, NW. It can be >> unsafe if we doesn't provide this information in polly IR. > Yes, if AffineSCEVIterator can iterate Truncate, ZeroExtend and > SignExtend correctly, polly can accept much more Scops. >> >> So I will mainly improve AffineSCEVIterator. Now I should to show test >> cases indicating that >> - loops with above-listed types expressions cannot be converted to the >> polyhedral representation >> - wrap flags are ignored and this can bring to broken programs (in >> fact, here I need some clarification) >> >> Do I understand correctly? > I think so. >> >> I have some QA skills. Is Polly in need of autoconf, cmake, buildbot >> setting up? Maybe this will be my tasks for first weeks > Looking forward to working with you :) >ether, does it mean that you can be the mentor?> best regards > ether >My proposal is here. Test cases will be added later. I would be pleased to hear some critical comments from you. = Proposal Polly uses own representation based on the polyhedral model. Polly has ScopDetection component which detects parts of the control flow graph which are candidates to be presented in the polyhedral representation. These parts are called Static Control Parts (SCoP). There is a requirement for SCoP that it can only contain affine linear expressionsin loop bounds and conditions. To understand if expressions suit to restriction ScopDetection converts it to affine linear form if possible. Currently ScopDetection supports only basic expressions add, addrec, mul and lacks support of min, max, sext, zext, trunc. For effectiveness it's good to detect as many as possible SCoPs, so the missed support should be added. Other problem is the following. Although ScopDetection support add and mul, it doesn't handle overflows "no signed wrap" and "no unsigned wrap". It can be unsafe if we don’t provide the pollyhedral representation with this information, so we can't guarantee it's safe to compile programs using Polly. My proposal is to solve these two problems by adding corresponding support. = Timeline So there are "checkpoints": Truncate, ZeroExtend, SignExtend, UdivExpr, UMaxExpr, SMaxExpr expressions and NSW/NUW wrap flags. My work will consist of the following steps: Weeks 1-2. Speeding-up. Implementing support for NSW/NUW wrap flags. Weeks 3-4. Implementing support for UMaxExpr, SMaxExpr. Weeks 5-6. Implementing support for ZeroExtend, SignExtend, Interim progress report. Weeks 7. Implementing support for Truncate. Weeks 8. Implementing support for UDivExpr. Weeks 9-12. Refactoring and documentation. Measurement of achieved results on benchmarks for coverage improvements. Final report. At each step I will add create tests for it. To prevent technical and organizational problems I will send as small patches as possible as soon as possible. = Why the project is interesting for me I want to dive into the world of real compiler technology and software development. An open-source project like LLVM-Polly is great opportunity to do useful things and acquire good knowledge and experience. = Benefits for LLVM o LLVM will be able to optimize a wider variety of programs. o After adding support of wrap flags there will be a guarantee that Polly produces correct transformation of any kind of LLVM IR. = About Me I am a fourth year student at Moscow State University, Department of Computational Mathematics and Cybernetics. My research area refers to parallelization on multiprocessor and multimachine system. I participate in the university development of parallel computing [1]. I have some compiler knowledge. I am familiar with common compiler theory [2] and GCC internals. My completed projects include implementing simple shell interpreter in C, Oberon interpreter in Java, SQL interpreter in C++. Also I have some knowledge in parallel programming with MPI and OpenMP. I worked on IBM BlueGene. = Contacts mail: krvladislav at gmail.com skype: krvladislav [1] http://www.keldysh.ru/dvm/dvmhtm1107/eng/index.html [2] Aho, Sethi, Ullman. Compilers: Principles, Techniques and Tools