Chandler Carruth via llvm-dev
2016-Feb-18 03:34 UTC
[llvm-dev] RFC: Add bitcode tests to test-suite
Some perhaps relevant aspects that make testing users of LLVM like Halide challenging: Halide uses the LLVM C++ APIs, but there isn't a good way to lock-step update it. So if we were to directly test Halide, it wouldn't link against the new LLVM. Practically speaking though, the LLVM IR generated by Halide should continue to work with newer LLVM optimizations and code generation. So the idea would be to snapshot the IR in bitcode (which is at least reasonably stable) so that we could replay the tests as LLVM changes. We can freshen the bitcode by re-generating it periodically so it doesn't drift too far from what Halide actually uses. The interesting questions IMO are: 1) Are folks happy using bitcode as the format here? I agree with Hal that it should be easy since Clang will actually Do The Right Thing if given a bitcode input. 2) Are folks happy with non-execution tests in some cases? I think Alina is looking at whether we can get a runtime library that will allow some of these to actually execute, but at least some of the tests are just snap-shots of a JIT, and would need the full Halide libraries (and introspection) to execute usefully. -Chandler On Wed, Feb 17, 2016 at 7:25 PM Hal Finkel via llvm-dev < llvm-dev at lists.llvm.org> wrote:> > ------------------------------ > > *From: *"Alina Sbirlea via llvm-dev" <llvm-dev at lists.llvm.org> > *To: *"llvm-dev" <llvm-dev at lists.llvm.org> > *Sent: *Wednesday, February 17, 2016 7:25:17 PM > *Subject: *[llvm-dev] RFC: Add bitcode tests to test-suite > > > > Hi all, > > TL;DR: Add *.bc to test-suite; llc *.bc; run some. > > We would like to propose adding bitcode tests to the llvm test-suite. > > Recent LLVM bugs [2-4] prompted us to look into upstreaming a subset of > the tests the Halide library [1] is running and we'd like the community's > feedback on moving forward with this. > > Halide uses LLVM and can generate bitcode, but we cannot add C++ tests to > test-suite without including the library itself. > This proposal is also potentially useful for other cases where there is no > C++ front-end. > > As a first step we are interested in adding a set of correctness tests, > for testing the IR without running the tests. Since these tests are > generated, they are not instrumented like the .ll files in trunk, however > we believe checking that llc runs without errors is still useful. > The bitcode files for Halide may also be large, so including them as > regression tests is not an option. If the smaller tests are found to be > valuable or covering cases no other tests cover, we can instrument them and > move them into the llvm trunk further along, but that is not the goal of > this proposal. > In addition, we're not sure whether the format for the tests should be .ll > or .bc, we're open to either. > > After this first step, we're interested in upstreaming bitcode tests and > also running them. > We are very interested in tests for multiple architectures, aarch64 in > particular, since this is where we have seen things break. This may > motivate adding .ll files rather than .bc in order to include the "RUN:" > target. > Where would these tests reside and with what directory structure? (similar > to test/CodeGen?) > > Suggestion on what's the best approach for extending the test-suite > framework for this proposal are more than welcome. > > We already have architecture-specific tests in the test suite (e.g. > SingleSource/UnitTests/Vector/{SSE,Altivec,etc.}, and Clang can deal with > IR inputs. I suppose you need to compile some corresponding runtime > library, but this does not seem like a big deal either. Mechanically, I > don't see this as particularly complicated. I think the real question is: > Is this the best way to have a kind of 'halide buildbot' that can inform > the LLVM developer community? > > -Hal > > > > This is just the high-level overview to start off the discussion, I'm sure > there are many more aspects to touch on. Looking forward to your feedback! > > Thanks, > Alina > > [1] http://halide-lang.org/ > [2] Broken: r259800 => Fixed: r260131 > [3] Broken: r260569 => Fixed: r260701 > [4] https://llvm.org/bugs/show_bug.cgi?id=26642 > > > > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev > > > > > -- > Hal Finkel > Assistant Computational Scientist > Leadership Computing Facility > Argonne National Laboratory > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20160218/7c554c6a/attachment.html>
Hal Finkel via llvm-dev
2016-Feb-18 04:53 UTC
[llvm-dev] RFC: Add bitcode tests to test-suite
----- Original Message -----> From: "Chandler Carruth" <chandlerc at google.com> > To: "Hal Finkel" <hfinkel at anl.gov>, "Alina Sbirlea" <alina.sbirlea at gmail.com> > Cc: "llvm-dev" <llvm-dev at lists.llvm.org> > Sent: Wednesday, February 17, 2016 9:34:24 PM > Subject: Re: [llvm-dev] RFC: Add bitcode tests to test-suite > > > Some perhaps relevant aspects that make testing users of LLVM like > Halide challenging: > > > Halide uses the LLVM C++ APIs, but there isn't a good way to > lock-step update it. So if we were to directly test Halide, it > wouldn't link against the new LLVM. > > > Practically speaking though, the LLVM IR generated by Halide should > continue to work with newer LLVM optimizations and code generation. > So the idea would be to snapshot the IR in bitcode (which is at > least reasonably stable) so that we could replay the tests as LLVM > changes. We can freshen the bitcode by re-generating it periodically > so it doesn't drift too far from what Halide actually uses. > > > The interesting questions IMO are: > > > 1) Are folks happy using bitcode as the format here? I agree with Hal > that it should be easy since Clang will actually Do The Right Thing > if given a bitcode input. > > > 2) Are folks happy with non-execution tests in some cases? I think > Alina is looking at whether we can get a runtime library that will > allow some of these to actually execute, but at least some of the > tests are just snap-shots of a JIT, and would need the full Halide > libraries (and introspection) to execute usefully. >As far as I can tell, Halide is < 100K LOC and has no external dependencies other than LLVM itself. I think we should just add it to the test suite. I realize that means the community updating it for API changes, but if the additional test coverage is as significant as I suspect, and the project authors will help and are responsive, that seems worthwhile. It is a JIT and a heavy generator of vector code, two areas in which our story on regular upstream testing coverage is not great. -Hal> > -Chandler > > > On Wed, Feb 17, 2016 at 7:25 PM Hal Finkel via llvm-dev < > llvm-dev at lists.llvm.org > wrote: > > > > > > > > > From: "Alina Sbirlea via llvm-dev" < llvm-dev at lists.llvm.org > > To: "llvm-dev" < llvm-dev at lists.llvm.org > > Sent: Wednesday, February 17, 2016 7:25:17 PM > Subject: [llvm-dev] RFC: Add bitcode tests to test-suite > > > > > > > Hi all, > > > TL;DR: Add *.bc to test-suite; llc *.bc; run some. > > > > We would like to propose adding bitcode tests to the llvm test-suite. > > > Recent LLVM bugs [2-4] prompted us to look into upstreaming a subset > of the tests the Halide library [1] is running and we'd like the > community's feedback on moving forward with this. > > > > Halide uses LLVM and can generate bitcode, but we cannot add C++ > tests to test-suite without including the library itself. > This proposal is also potentially useful for other cases where there > is no C++ front-end. > > > As a first step we are interested in adding a set of correctness > tests, for testing the IR without running the tests. Since these > tests are generated, they are not instrumented like the .ll files in > trunk, however we believe checking that llc runs without errors is > still useful. > The bitcode files for Halide may also be large, so including them as > regression tests is not an option. If the smaller tests are found to > be valuable or covering cases no other tests cover, we can > instrument them and move them into the llvm trunk further along, but > that is not the goal of this proposal. > In addition, we're not sure whether the format for the tests should > be .ll or .bc, we're open to either. > > > After this first step, we're interested in upstreaming bitcode tests > and also running them. > We are very interested in tests for multiple architectures, aarch64 > in particular, since this is where we have seen things break. This > may motivate adding .ll files rather than .bc in order to include > the "RUN:" target. > Where would these tests reside and with what directory structure? > (similar to test/CodeGen?) > > > Suggestion on what's the best approach for extending the test-suite > framework for this proposal are more than welcome. > > > > We already have architecture-specific tests in the test suite (e.g. > SingleSource/UnitTests/Vector/{SSE,Altivec,etc.}, and Clang can deal > with IR inputs. I suppose you need to compile some corresponding > runtime library, but this does not seem like a big deal either. > Mechanically, I don't see this as particularly complicated. I think > the real question is: Is this the best way to have a kind of 'halide > buildbot' that can inform the LLVM developer community? > > -Hal > > > > > > > > > > > This is just the high-level overview to start off the discussion, I'm > sure there are many more aspects to touch on. Looking forward to > your feedback! > > > > Thanks, > Alina > > > [1] http:// halide -lang.org/ > [2] Broken: r259800 => Fixed: r260131 > [3] Broken: r260569 => Fixed: r260701 > > [4] https://llvm.org/bugs/show_bug.cgi?id=26642 > > > > > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev > > > > > > -- > > Hal Finkel > Assistant Computational Scientist > Leadership Computing Facility > Argonne National Laboratory > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-- Hal Finkel Assistant Computational Scientist Leadership Computing Facility Argonne National Laboratory
Alina Sbirlea via llvm-dev
2016-Feb-18 05:27 UTC
[llvm-dev] RFC: Add bitcode tests to test-suite
>I think the real question is: Is this the best way to have a kind of'halide buildbot' that can inform the LLVM developer community? Halide already has a buildbot running every few hours which is being used to inform LLVM developer community when something breaks. It would be a lot more useful however to have the tests in an LLVM repository to inform LLVM devs which test broke right away. You're right that the underlying reason is the fact that Halide has test coverage of areas currently not covered.> As far as I can tell, Halide is < 100K LOC and has no externaldependencies other than LLVM itself. I think we should just add it to the test suite. I realize that means the community updating it for API changes, but if the additional test coverage is as significant as I suspect, and the project authors will help and are responsive, that seems worthwhile. It is a JIT and a heavy generator of vector code, two areas in which our story on regular upstream testing coverage is not great. Halide can do both JIT and AOT compilation. Would the community be happy to have non-execution tests for the JITted tests and execution tests for the AOT ones? This would in theory use a small set of Halide and not need the entire library, which is what we are trying to avoid here. The approach is meant to not clutter test-suite with a sizable amount of code but still get the test coverage offered by Halide. On Wed, Feb 17, 2016 at 8:53 PM, Hal Finkel <hfinkel at anl.gov> wrote:> ----- Original Message ----- > > From: "Chandler Carruth" <chandlerc at google.com> > > To: "Hal Finkel" <hfinkel at anl.gov>, "Alina Sbirlea" < > alina.sbirlea at gmail.com> > > Cc: "llvm-dev" <llvm-dev at lists.llvm.org> > > Sent: Wednesday, February 17, 2016 9:34:24 PM > > Subject: Re: [llvm-dev] RFC: Add bitcode tests to test-suite > > > > > > Some perhaps relevant aspects that make testing users of LLVM like > > Halide challenging: > > > > > > Halide uses the LLVM C++ APIs, but there isn't a good way to > > lock-step update it. So if we were to directly test Halide, it > > wouldn't link against the new LLVM. > > > > > > Practically speaking though, the LLVM IR generated by Halide should > > continue to work with newer LLVM optimizations and code generation. > > So the idea would be to snapshot the IR in bitcode (which is at > > least reasonably stable) so that we could replay the tests as LLVM > > changes. We can freshen the bitcode by re-generating it periodically > > so it doesn't drift too far from what Halide actually uses. > > > > > > The interesting questions IMO are: > > > > > > 1) Are folks happy using bitcode as the format here? I agree with Hal > > that it should be easy since Clang will actually Do The Right Thing > > if given a bitcode input. > > > > > > 2) Are folks happy with non-execution tests in some cases? I think > > Alina is looking at whether we can get a runtime library that will > > allow some of these to actually execute, but at least some of the > > tests are just snap-shots of a JIT, and would need the full Halide > > libraries (and introspection) to execute usefully. > > > > As far as I can tell, Halide is < 100K LOC and has no external > dependencies other than LLVM itself. I think we should just add it to the > test suite. I realize that means the community updating it for API changes, > but if the additional test coverage is as significant as I suspect, and the > project authors will help and are responsive, that seems worthwhile. It is > a JIT and a heavy generator of vector code, two areas in which our story on > regular upstream testing coverage is not great. > > -Hal > > > > > -Chandler > > > > > > On Wed, Feb 17, 2016 at 7:25 PM Hal Finkel via llvm-dev < > > llvm-dev at lists.llvm.org > wrote: > > > > > > > > > > > > > > > > > > From: "Alina Sbirlea via llvm-dev" < llvm-dev at lists.llvm.org > > > To: "llvm-dev" < llvm-dev at lists.llvm.org > > > Sent: Wednesday, February 17, 2016 7:25:17 PM > > Subject: [llvm-dev] RFC: Add bitcode tests to test-suite > > > > > > > > > > > > > > Hi all, > > > > > > TL;DR: Add *.bc to test-suite; llc *.bc; run some. > > > > > > > > We would like to propose adding bitcode tests to the llvm test-suite. > > > > > > Recent LLVM bugs [2-4] prompted us to look into upstreaming a subset > > of the tests the Halide library [1] is running and we'd like the > > community's feedback on moving forward with this. > > > > > > > > Halide uses LLVM and can generate bitcode, but we cannot add C++ > > tests to test-suite without including the library itself. > > This proposal is also potentially useful for other cases where there > > is no C++ front-end. > > > > > > As a first step we are interested in adding a set of correctness > > tests, for testing the IR without running the tests. Since these > > tests are generated, they are not instrumented like the .ll files in > > trunk, however we believe checking that llc runs without errors is > > still useful. > > The bitcode files for Halide may also be large, so including them as > > regression tests is not an option. If the smaller tests are found to > > be valuable or covering cases no other tests cover, we can > > instrument them and move them into the llvm trunk further along, but > > that is not the goal of this proposal. > > In addition, we're not sure whether the format for the tests should > > be .ll or .bc, we're open to either. > > > > > > After this first step, we're interested in upstreaming bitcode tests > > and also running them. > > We are very interested in tests for multiple architectures, aarch64 > > in particular, since this is where we have seen things break. This > > may motivate adding .ll files rather than .bc in order to include > > the "RUN:" target. > > Where would these tests reside and with what directory structure? > > (similar to test/CodeGen?) > > > > > > Suggestion on what's the best approach for extending the test-suite > > framework for this proposal are more than welcome. > > > > > > > > We already have architecture-specific tests in the test suite (e.g. > > SingleSource/UnitTests/Vector/{SSE,Altivec,etc.}, and Clang can deal > > with IR inputs. I suppose you need to compile some corresponding > > runtime library, but this does not seem like a big deal either. > > Mechanically, I don't see this as particularly complicated. I think > > the real question is: Is this the best way to have a kind of 'halide > > buildbot' that can inform the LLVM developer community? > > > > -Hal > > > > > > > > > > > > > > > > > > > > > > This is just the high-level overview to start off the discussion, I'm > > sure there are many more aspects to touch on. Looking forward to > > your feedback! > > > > > > > > Thanks, > > Alina > > > > > > [1] http:// halide -lang.org/ > > [2] Broken: r259800 => Fixed: r260131 > > [3] Broken: r260569 => Fixed: r260701 > > > > [4] https://llvm.org/bugs/show_bug.cgi?id=26642 > > > > > > > > > > _______________________________________________ > > LLVM Developers mailing list > > llvm-dev at lists.llvm.org > > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev > > > > > > > > > > > > -- > > > > Hal Finkel > > Assistant Computational Scientist > > Leadership Computing Facility > > Argonne National Laboratory > > _______________________________________________ > > LLVM Developers mailing list > > llvm-dev at lists.llvm.org > > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev > > > > -- > Hal Finkel > Assistant Computational Scientist > Leadership Computing Facility > Argonne National Laboratory >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20160217/23ca2408/attachment-0001.html>
Hal Finkel via llvm-dev
2016-Feb-18 14:54 UTC
[llvm-dev] RFC: Add bitcode tests to test-suite
Hi Chandler, et al., While this proposal to put IR into the test suite technically non-problematic, I've convinced myself that this is a suboptimal direction for the LLVM project. Here's what I think would be better: - We create a test-suite/Frontends directory, and open this directory to actively-maintained external frontends, subject to the following restrictions: - The frontend must be actively maintained, and the project must agree to actively maintain the test-suite version - The frontend must use the LLVM API (either C or C++) - no printing textual IR - The frontend must have no significant (non-optional) dependencies outside of LLVM itself, or things on which LLVM itself depends - The frontend must have regression tests and benchmarks/correctness tests providing significant coverage of the frontend and its associated code generation Here's the quid pro quo: - The LLVM community gains additional testing coverage (which we definitely need) - The LLVM community gains extra insight into how its APIs are being used (hopefully allowing us to make more-informed decisions about how to update them) - The frontend gains free API updates - The frontend's use of LLVM will be more stable This involves extra work for everybody, but will help us all deliver higher-quality products. Plus, given the constant discussions about the difficulty for external projects to follow API updates, etc., this is a good way to help address those difficulties. The fact that Halide will provide extra coverage of our vector code generation (aside from whatever we happen to produce from our autovectorizers), and our JIT infrastructure, makes it a good candidate for this. Intel's ispc, POCL, (maybe whatever bit of Mesa uses LLVM), etc. would also be natural candidates should the projects be interested. Thanks again, Hal ----- Original Message -----> From: "Chandler Carruth" <chandlerc at google.com> > To: "Hal Finkel" <hfinkel at anl.gov>, "Alina Sbirlea" <alina.sbirlea at gmail.com> > Cc: "llvm-dev" <llvm-dev at lists.llvm.org> > Sent: Wednesday, February 17, 2016 9:34:24 PM > Subject: Re: [llvm-dev] RFC: Add bitcode tests to test-suite > > > Some perhaps relevant aspects that make testing users of LLVM like > Halide challenging: > > > Halide uses the LLVM C++ APIs, but there isn't a good way to > lock-step update it. So if we were to directly test Halide, it > wouldn't link against the new LLVM. > > > Practically speaking though, the LLVM IR generated by Halide should > continue to work with newer LLVM optimizations and code generation. > So the idea would be to snapshot the IR in bitcode (which is at > least reasonably stable) so that we could replay the tests as LLVM > changes. We can freshen the bitcode by re-generating it periodically > so it doesn't drift too far from what Halide actually uses. > > > The interesting questions IMO are: > > > 1) Are folks happy using bitcode as the format here? I agree with Hal > that it should be easy since Clang will actually Do The Right Thing > if given a bitcode input. > > > 2) Are folks happy with non-execution tests in some cases? I think > Alina is looking at whether we can get a runtime library that will > allow some of these to actually execute, but at least some of the > tests are just snap-shots of a JIT, and would need the full Halide > libraries (and introspection) to execute usefully. > > > -Chandler > > > On Wed, Feb 17, 2016 at 7:25 PM Hal Finkel via llvm-dev < > llvm-dev at lists.llvm.org > wrote: > > > > > > > > > From: "Alina Sbirlea via llvm-dev" < llvm-dev at lists.llvm.org > > To: "llvm-dev" < llvm-dev at lists.llvm.org > > Sent: Wednesday, February 17, 2016 7:25:17 PM > Subject: [llvm-dev] RFC: Add bitcode tests to test-suite > > > > > > > Hi all, > > > TL;DR: Add *.bc to test-suite; llc *.bc; run some. > > > > We would like to propose adding bitcode tests to the llvm test-suite. > > > Recent LLVM bugs [2-4] prompted us to look into upstreaming a subset > of the tests the Halide library [1] is running and we'd like the > community's feedback on moving forward with this. > > > > Halide uses LLVM and can generate bitcode, but we cannot add C++ > tests to test-suite without including the library itself. > This proposal is also potentially useful for other cases where there > is no C++ front-end. > > > As a first step we are interested in adding a set of correctness > tests, for testing the IR without running the tests. Since these > tests are generated, they are not instrumented like the .ll files in > trunk, however we believe checking that llc runs without errors is > still useful. > The bitcode files for Halide may also be large, so including them as > regression tests is not an option. If the smaller tests are found to > be valuable or covering cases no other tests cover, we can > instrument them and move them into the llvm trunk further along, but > that is not the goal of this proposal. > In addition, we're not sure whether the format for the tests should > be .ll or .bc, we're open to either. > > > After this first step, we're interested in upstreaming bitcode tests > and also running them. > We are very interested in tests for multiple architectures, aarch64 > in particular, since this is where we have seen things break. This > may motivate adding .ll files rather than .bc in order to include > the "RUN:" target. > Where would these tests reside and with what directory structure? > (similar to test/CodeGen?) > > > Suggestion on what's the best approach for extending the test-suite > framework for this proposal are more than welcome. > > > > We already have architecture-specific tests in the test suite (e.g. > SingleSource/UnitTests/Vector/{SSE,Altivec,etc.}, and Clang can deal > with IR inputs. I suppose you need to compile some corresponding > runtime library, but this does not seem like a big deal either. > Mechanically, I don't see this as particularly complicated. I think > the real question is: Is this the best way to have a kind of 'halide > buildbot' that can inform the LLVM developer community? > > -Hal > > > > > > > > > > > This is just the high-level overview to start off the discussion, I'm > sure there are many more aspects to touch on. Looking forward to > your feedback! > > > > Thanks, > Alina > > > [1] http:// halide -lang.org/ > [2] Broken: r259800 => Fixed: r260131 > [3] Broken: r260569 => Fixed: r260701 > > [4] https://llvm.org/bugs/show_bug.cgi?id=26642 > > > > > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev > > > > > > -- > > Hal Finkel > Assistant Computational Scientist > Leadership Computing Facility > Argonne National Laboratory > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-- Hal Finkel Assistant Computational Scientist Leadership Computing Facility Argonne National Laboratory
David Blaikie via llvm-dev
2016-Feb-18 16:19 UTC
[llvm-dev] RFC: Add bitcode tests to test-suite
On Thu, Feb 18, 2016 at 6:54 AM, Hal Finkel via llvm-dev < llvm-dev at lists.llvm.org> wrote:> Hi Chandler, et al., > > While this proposal to put IR into the test suite technically > non-problematic, I've convinced myself that this is a suboptimal direction > for the LLVM project. Here's what I think would be better: > > - We create a test-suite/Frontends directory, and open this directory to > actively-maintained external frontends, subject to the following > restrictions: > > - The frontend must be actively maintained, and the project must agree > to actively maintain the test-suite version > - The frontend must use the LLVM API (either C or C++) - no printing > textual IR > - The frontend must have no significant (non-optional) dependencies > outside of LLVM itself, or things on which LLVM itself depends > - The frontend must have regression tests and benchmarks/correctness > tests providing significant coverage of the frontend and its associated > code generation > > Here's the quid pro quo: > > - The LLVM community gains additional testing coverage (which we > definitely need) > - The LLVM community gains extra insight into how its APIs are being > used (hopefully allowing us to make more-informed decisions about how to > update them) > > - The frontend gains free API updates > - The frontend's use of LLVM will be more stable > > This involves extra work for everybody, but will help us all deliver > higher-quality products. Plus, given the constant discussions about the > difficulty for external projects to follow API updates, etc., this is a > good way to help address those difficulties. >Given the extra cost it incurs on LLVM developers changing APIs, this seems like a problematic tradeoff/not necessarily good. LLVM moves quickly because it can/it is beneficial, this causes pain/cost to out-of-tree projects. Moving that cost to LLVM would simply make LLVM move more slowly/API changes would be made less frequently. I'm not sure that's the right tradeoff - the LLVM project would end up paying the cost of the external project but not gaining the advantages of the project being part of the LLVM Project umbrella (the developers wouldn't be contributing back to the LLVM community/codebase, etc as they would if it were more of a Clang, or LLD, etc).> > The fact that Halide will provide extra coverage of our vector code > generation (aside from whatever we happen to produce from our > autovectorizers), and our JIT infrastructure, makes it a good candidate for > this. Intel's ispc, POCL, (maybe whatever bit of Mesa uses LLVM), etc. > would also be natural candidates should the projects be interested. > > Thanks again, > Hal > > ----- Original Message ----- > > From: "Chandler Carruth" <chandlerc at google.com> > > To: "Hal Finkel" <hfinkel at anl.gov>, "Alina Sbirlea" < > alina.sbirlea at gmail.com> > > Cc: "llvm-dev" <llvm-dev at lists.llvm.org> > > Sent: Wednesday, February 17, 2016 9:34:24 PM > > Subject: Re: [llvm-dev] RFC: Add bitcode tests to test-suite > > > > > > Some perhaps relevant aspects that make testing users of LLVM like > > Halide challenging: > > > > > > Halide uses the LLVM C++ APIs, but there isn't a good way to > > lock-step update it. So if we were to directly test Halide, it > > wouldn't link against the new LLVM. > > > > > > Practically speaking though, the LLVM IR generated by Halide should > > continue to work with newer LLVM optimizations and code generation. > > So the idea would be to snapshot the IR in bitcode (which is at > > least reasonably stable) so that we could replay the tests as LLVM > > changes. We can freshen the bitcode by re-generating it periodically > > so it doesn't drift too far from what Halide actually uses. > > > > > > The interesting questions IMO are: > > > > > > 1) Are folks happy using bitcode as the format here? I agree with Hal > > that it should be easy since Clang will actually Do The Right Thing > > if given a bitcode input. > > > > > > 2) Are folks happy with non-execution tests in some cases? I think > > Alina is looking at whether we can get a runtime library that will > > allow some of these to actually execute, but at least some of the > > tests are just snap-shots of a JIT, and would need the full Halide > > libraries (and introspection) to execute usefully. > > > > > > -Chandler > > > > > > On Wed, Feb 17, 2016 at 7:25 PM Hal Finkel via llvm-dev < > > llvm-dev at lists.llvm.org > wrote: > > > > > > > > > > > > > > > > > > From: "Alina Sbirlea via llvm-dev" < llvm-dev at lists.llvm.org > > > To: "llvm-dev" < llvm-dev at lists.llvm.org > > > Sent: Wednesday, February 17, 2016 7:25:17 PM > > Subject: [llvm-dev] RFC: Add bitcode tests to test-suite > > > > > > > > > > > > > > Hi all, > > > > > > TL;DR: Add *.bc to test-suite; llc *.bc; run some. > > > > > > > > We would like to propose adding bitcode tests to the llvm test-suite. > > > > > > Recent LLVM bugs [2-4] prompted us to look into upstreaming a subset > > of the tests the Halide library [1] is running and we'd like the > > community's feedback on moving forward with this. > > > > > > > > Halide uses LLVM and can generate bitcode, but we cannot add C++ > > tests to test-suite without including the library itself. > > This proposal is also potentially useful for other cases where there > > is no C++ front-end. > > > > > > As a first step we are interested in adding a set of correctness > > tests, for testing the IR without running the tests. Since these > > tests are generated, they are not instrumented like the .ll files in > > trunk, however we believe checking that llc runs without errors is > > still useful. > > The bitcode files for Halide may also be large, so including them as > > regression tests is not an option. If the smaller tests are found to > > be valuable or covering cases no other tests cover, we can > > instrument them and move them into the llvm trunk further along, but > > that is not the goal of this proposal. > > In addition, we're not sure whether the format for the tests should > > be .ll or .bc, we're open to either. > > > > > > After this first step, we're interested in upstreaming bitcode tests > > and also running them. > > We are very interested in tests for multiple architectures, aarch64 > > in particular, since this is where we have seen things break. This > > may motivate adding .ll files rather than .bc in order to include > > the "RUN:" target. > > Where would these tests reside and with what directory structure? > > (similar to test/CodeGen?) > > > > > > Suggestion on what's the best approach for extending the test-suite > > framework for this proposal are more than welcome. > > > > > > > > We already have architecture-specific tests in the test suite (e.g. > > SingleSource/UnitTests/Vector/{SSE,Altivec,etc.}, and Clang can deal > > with IR inputs. I suppose you need to compile some corresponding > > runtime library, but this does not seem like a big deal either. > > Mechanically, I don't see this as particularly complicated. I think > > the real question is: Is this the best way to have a kind of 'halide > > buildbot' that can inform the LLVM developer community? > > > > -Hal > > > > > > > > > > > > > > > > > > > > > > This is just the high-level overview to start off the discussion, I'm > > sure there are many more aspects to touch on. Looking forward to > > your feedback! > > > > > > > > Thanks, > > Alina > > > > > > [1] http:// halide -lang.org/ > > [2] Broken: r259800 => Fixed: r260131 > > [3] Broken: r260569 => Fixed: r260701 > > > > [4] https://llvm.org/bugs/show_bug.cgi?id=26642 > > > > > > > > > > _______________________________________________ > > LLVM Developers mailing list > > llvm-dev at lists.llvm.org > > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev > > > > > > > > > > > > -- > > > > Hal Finkel > > Assistant Computational Scientist > > Leadership Computing Facility > > Argonne National Laboratory > > _______________________________________________ > > LLVM Developers mailing list > > llvm-dev at lists.llvm.org > > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev > > > > -- > Hal Finkel > Assistant Computational Scientist > Leadership Computing Facility > Argonne National Laboratory > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-------------- next part -------------- An HTML attachment was scrubbed... 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Philip Reames via llvm-dev
2016-Feb-18 16:42 UTC
[llvm-dev] RFC: Add bitcode tests to test-suite
On 02/18/2016 06:54 AM, Hal Finkel via llvm-dev wrote:> Hi Chandler, et al., > > While this proposal to put IR into the test suite technically non-problematic, I've convinced myself that this is a suboptimal direction for the LLVM project. Here's what I think would be better: > > - We create a test-suite/Frontends directory, and open this directory to actively-maintained external frontends, subject to the following restrictions: > > - The frontend must be actively maintained, and the project must agree to actively maintain the test-suite version > - The frontend must use the LLVM API (either C or C++) - no printing textual IR > - The frontend must have no significant (non-optional) dependencies outside of LLVM itself, or things on which LLVM itself depends > - The frontend must have regression tests and benchmarks/correctness tests providing significant coverage of the frontend and its associated code generation > > Here's the quid pro quo: > > - The LLVM community gains additional testing coverage (which we definitely need) > - The LLVM community gains extra insight into how its APIs are being used (hopefully allowing us to make more-informed decisions about how to update them) > > - The frontend gains free API updates > - The frontend's use of LLVM will be more stable > > This involves extra work for everybody, but will help us all deliver higher-quality products. Plus, given the constant discussions about the difficulty for external projects to follow API updates, etc., this is a good way to help address those difficulties. > > The fact that Halide will provide extra coverage of our vector code generation (aside from whatever we happen to produce from our autovectorizers), and our JIT infrastructure, makes it a good candidate for this. Intel's ispc, POCL, (maybe whatever bit of Mesa uses LLVM), etc. would also be natural candidates should the projects be interested.I think this is a really bad tradeoff and am strongly opposed to this proposal. If we want to focus on improving test coverage, that's reasonable, but doing so at the cost of requiring LLVM contributors to maintain everyone's frontend is not a reasonable approach. A couple of alternate approaches which might be worth considering: 1) The IR corpus approach mentioned previously. So long as external teams are willing to update the corpus regularly (weekly), this gives most of the backend coverage with none of the maintenance burden. 2) Use coverage information to determine which code paths Halide covers which are not covered by existing unit tests. Work to improve those unit tests. Using something along the lines with a mutation testing (i.e. change the source code and see what breaks), combined with test reduction (bugpoint), could greatly improve our test coverage in tree fairly quickly. This would require a lot of work from a single contributor, but that's much better than requiring a lot of work from all contributors.> > Thanks again, > Hal > > ----- Original Message ----- >> From: "Chandler Carruth" <chandlerc at google.com> >> To: "Hal Finkel" <hfinkel at anl.gov>, "Alina Sbirlea" <alina.sbirlea at gmail.com> >> Cc: "llvm-dev" <llvm-dev at lists.llvm.org> >> Sent: Wednesday, February 17, 2016 9:34:24 PM >> Subject: Re: [llvm-dev] RFC: Add bitcode tests to test-suite >> >> >> Some perhaps relevant aspects that make testing users of LLVM like >> Halide challenging: >> >> >> Halide uses the LLVM C++ APIs, but there isn't a good way to >> lock-step update it. So if we were to directly test Halide, it >> wouldn't link against the new LLVM. >> >> >> Practically speaking though, the LLVM IR generated by Halide should >> continue to work with newer LLVM optimizations and code generation. >> So the idea would be to snapshot the IR in bitcode (which is at >> least reasonably stable) so that we could replay the tests as LLVM >> changes. We can freshen the bitcode by re-generating it periodically >> so it doesn't drift too far from what Halide actually uses. >> >> >> The interesting questions IMO are: >> >> >> 1) Are folks happy using bitcode as the format here? I agree with Hal >> that it should be easy since Clang will actually Do The Right Thing >> if given a bitcode input. >> >> >> 2) Are folks happy with non-execution tests in some cases? I think >> Alina is looking at whether we can get a runtime library that will >> allow some of these to actually execute, but at least some of the >> tests are just snap-shots of a JIT, and would need the full Halide >> libraries (and introspection) to execute usefully. >> >> >> -Chandler >> >> >> On Wed, Feb 17, 2016 at 7:25 PM Hal Finkel via llvm-dev < >> llvm-dev at lists.llvm.org > wrote: >> >> >> >> >> >> >> >> >> From: "Alina Sbirlea via llvm-dev" < llvm-dev at lists.llvm.org > >> To: "llvm-dev" < llvm-dev at lists.llvm.org > >> Sent: Wednesday, February 17, 2016 7:25:17 PM >> Subject: [llvm-dev] RFC: Add bitcode tests to test-suite >> >> >> >> >> >> >> Hi all, >> >> >> TL;DR: Add *.bc to test-suite; llc *.bc; run some. >> >> >> >> We would like to propose adding bitcode tests to the llvm test-suite. >> >> >> Recent LLVM bugs [2-4] prompted us to look into upstreaming a subset >> of the tests the Halide library [1] is running and we'd like the >> community's feedback on moving forward with this. >> >> >> >> Halide uses LLVM and can generate bitcode, but we cannot add C++ >> tests to test-suite without including the library itself. >> This proposal is also potentially useful for other cases where there >> is no C++ front-end. >> >> >> As a first step we are interested in adding a set of correctness >> tests, for testing the IR without running the tests. Since these >> tests are generated, they are not instrumented like the .ll files in >> trunk, however we believe checking that llc runs without errors is >> still useful. >> The bitcode files for Halide may also be large, so including them as >> regression tests is not an option. If the smaller tests are found to >> be valuable or covering cases no other tests cover, we can >> instrument them and move them into the llvm trunk further along, but >> that is not the goal of this proposal. >> In addition, we're not sure whether the format for the tests should >> be .ll or .bc, we're open to either. >> >> >> After this first step, we're interested in upstreaming bitcode tests >> and also running them. >> We are very interested in tests for multiple architectures, aarch64 >> in particular, since this is where we have seen things break. This >> may motivate adding .ll files rather than .bc in order to include >> the "RUN:" target. >> Where would these tests reside and with what directory structure? >> (similar to test/CodeGen?) >> >> >> Suggestion on what's the best approach for extending the test-suite >> framework for this proposal are more than welcome. >> >> >> >> We already have architecture-specific tests in the test suite (e.g. >> SingleSource/UnitTests/Vector/{SSE,Altivec,etc.}, and Clang can deal >> with IR inputs. I suppose you need to compile some corresponding >> runtime library, but this does not seem like a big deal either. >> Mechanically, I don't see this as particularly complicated. I think >> the real question is: Is this the best way to have a kind of 'halide >> buildbot' that can inform the LLVM developer community? >> >> -Hal >> >> >> >> >> >> >> >> >> >> >> This is just the high-level overview to start off the discussion, I'm >> sure there are many more aspects to touch on. Looking forward to >> your feedback! >> >> >> >> Thanks, >> Alina >> >> >> [1] http:// halide -lang.org/ >> [2] Broken: r259800 => Fixed: r260131 >> [3] Broken: r260569 => Fixed: r260701 >> >> [4] https://llvm.org/bugs/show_bug.cgi?id=26642 >> >> >> >> >> _______________________________________________ >> LLVM Developers mailing list >> llvm-dev at lists.llvm.org >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >> >> >> >> >> >> -- >> >> Hal Finkel >> Assistant Computational Scientist >> Leadership Computing Facility >> Argonne National Laboratory >> _______________________________________________ >> LLVM Developers mailing list >> llvm-dev at lists.llvm.org >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >>