Lang Hames via llvm-dev
2020-Sep-28 03:29 UTC
[llvm-dev] LLVM Developers Meeting JIT BoF -- Request for Topics of Interest
Hi Andres, A topic that I'd find interesting is what it'd take to make it easier to> use profile guided optimization in the context of JIT. A few years back > I crudely hacked this together, but it was fairly ugly. It'd be nice to > make that easier. Possibly too complicated for that type of session?We couldn't go into detail, but we could kick off a discussion and identify who is interested in working on this. My pitch: We should solve this by investing in JITLink and implementing profiling (and debugger support) via ObjectLinkingLayer::Plugins. Maybe a brief overview of / discussion on how these work would be useful? -- Lang. On Fri, Sep 25, 2020 at 7:19 PM Andres Freund <andres at anarazel.de> wrote:> Hi, > > On 2020-09-25 19:05:42 -0700, Lang Hames wrote: > > The 2020 Virtual LLVM Developer's Meeting is coming up the week after > next. > > I'll be hosting a JIT Birds-of-a-Feather session on Thursday the 8th at > > 10:55am PDT (See http://llvm.org/devmtg/2020-09/schedule/). I'm > planning to > > run this more like a Round Table: Minimal introduction, plenty of time > for > > discussion. > > > > Does anyone have any LLVM JIT related topics that they would particularly > > like to discuss at this session? Any questions that they think could be > > best answered by a round-table style discussion? I'll aim to rope in the > > right people and prepare answers to make sure we get the most out of the > > session. > > A topic that I'd find interesting is what it'd take to make it easier to > use profile guided optimization in the context of JIT. A few years back > I crudely hacked this together, but it was fairly ugly. It'd be nice to > make that easier. Possibly too complicated for that type of session? > > I dimly recall that the main issue was that there is no good way to > extract the profile information without going through files / applying > the profile data without going through files. > > Greetings, > > Andres Freund >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20200927/4d7feb35/attachment.html>
Geoff Levner via llvm-dev
2020-Sep-28 14:18 UTC
[llvm-dev] LLVM Developers Meeting JIT BoF -- Request for Topics of Interest
Importing symbols into the JIT from an object file or static library...? On Mon, Sep 28, 2020 at 5:29 AM Lang Hames <lhames at gmail.com> wrote:> Hi Andres, > > A topic that I'd find interesting is what it'd take to make it easier to >> use profile guided optimization in the context of JIT. A few years back >> I crudely hacked this together, but it was fairly ugly. It'd be nice to >> make that easier. Possibly too complicated for that type of session? > > > We couldn't go into detail, but we could kick off a discussion and > identify who is interested in working on this. My pitch: We should solve > this by investing in JITLink and implementing profiling (and debugger > support) via ObjectLinkingLayer::Plugins. Maybe a brief overview of / > discussion on how these work would be useful? > > -- Lang. > > > On Fri, Sep 25, 2020 at 7:19 PM Andres Freund <andres at anarazel.de> wrote: > >> Hi, >> >> On 2020-09-25 19:05:42 -0700, Lang Hames wrote: >> > The 2020 Virtual LLVM Developer's Meeting is coming up the week after >> next. >> > I'll be hosting a JIT Birds-of-a-Feather session on Thursday the 8th at >> > 10:55am PDT (See http://llvm.org/devmtg/2020-09/schedule/). I'm >> planning to >> > run this more like a Round Table: Minimal introduction, plenty of time >> for >> > discussion. >> > >> > Does anyone have any LLVM JIT related topics that they would >> particularly >> > like to discuss at this session? Any questions that they think could be >> > best answered by a round-table style discussion? I'll aim to rope in the >> > right people and prepare answers to make sure we get the most out of the >> > session. >> >> A topic that I'd find interesting is what it'd take to make it easier to >> use profile guided optimization in the context of JIT. A few years back >> I crudely hacked this together, but it was fairly ugly. It'd be nice to >> make that easier. Possibly too complicated for that type of session? >> >> I dimly recall that the main issue was that there is no good way to >> extract the profile information without going through files / applying >> the profile data without going through files. >> >> Greetings, >> >> Andres Freund >> >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20200928/87d7c032/attachment.html>
Lang Hames via llvm-dev
2020-Sep-28 20:56 UTC
[llvm-dev] LLVM Developers Meeting JIT BoF -- Request for Topics of Interest
Hi Geoff, Importing symbols into the JIT from an object file or static library...? Sure! Are you interested in doing this with the C API, LLJIT, or raw OrcV2 components? The high-level answer here (which we can dig into further in the BoF) is: For object files: - For raw OrcV2 components you'll want to create an RTDyldObjectLinkingLayer or ObjectLinkingLayer and use the 'add' method. - For an LLJIT instance you can just call the 'addObjectFile' method. - For the OrcV2 C API you can call the 'LLVMOrcLLJITAddObjectFile' function. For static libraries: - For raw OrcV2 components or an LLJIT instance you can attach a StaticLibraryDefinitionGenerator [1] to the JITDylib that you would like to load the library into. See [2] for an example. - For the OrcV2 C API we will just need to add a method to wrap the operation above. We already have 'LLVMOrcCreateDynamicLibrarySearchGeneratorForProcess'. We should add counterparts to that to load dynamic and static libraries from paths. -- Lang. [1] https://github.com/llvm/llvm-project/blob/5aa56b242951ab0f0181386ea58509f19b09206e/llvm/include/llvm/ExecutionEngine/Orc/ExecutionUtils.h#L361 [2] https://github.com/llvm/llvm-project/blob/e7549dafcd33ced4280a81ca1d1ee4cc78ed253f/llvm/tools/lli/lli.cpp#L968 On Mon, Sep 28, 2020 at 7:18 AM Geoff Levner <glevner at gmail.com> wrote:> Importing symbols into the JIT from an object file or static library...? > > On Mon, Sep 28, 2020 at 5:29 AM Lang Hames <lhames at gmail.com> wrote: > >> Hi Andres, >> >> A topic that I'd find interesting is what it'd take to make it easier to >>> use profile guided optimization in the context of JIT. A few years back >>> I crudely hacked this together, but it was fairly ugly. It'd be nice to >>> make that easier. Possibly too complicated for that type of session? >> >> >> We couldn't go into detail, but we could kick off a discussion and >> identify who is interested in working on this. My pitch: We should solve >> this by investing in JITLink and implementing profiling (and debugger >> support) via ObjectLinkingLayer::Plugins. Maybe a brief overview of / >> discussion on how these work would be useful? >> >> -- Lang. >> >> >> On Fri, Sep 25, 2020 at 7:19 PM Andres Freund <andres at anarazel.de> wrote: >> >>> Hi, >>> >>> On 2020-09-25 19:05:42 -0700, Lang Hames wrote: >>> > The 2020 Virtual LLVM Developer's Meeting is coming up the week after >>> next. >>> > I'll be hosting a JIT Birds-of-a-Feather session on Thursday the 8th at >>> > 10:55am PDT (See http://llvm.org/devmtg/2020-09/schedule/). I'm >>> planning to >>> > run this more like a Round Table: Minimal introduction, plenty of time >>> for >>> > discussion. >>> > >>> > Does anyone have any LLVM JIT related topics that they would >>> particularly >>> > like to discuss at this session? Any questions that they think could be >>> > best answered by a round-table style discussion? I'll aim to rope in >>> the >>> > right people and prepare answers to make sure we get the most out of >>> the >>> > session. >>> >>> A topic that I'd find interesting is what it'd take to make it easier to >>> use profile guided optimization in the context of JIT. A few years back >>> I crudely hacked this together, but it was fairly ugly. It'd be nice to >>> make that easier. Possibly too complicated for that type of session? >>> >>> I dimly recall that the main issue was that there is no good way to >>> extract the profile information without going through files / applying >>> the profile data without going through files. >>> >>> Greetings, >>> >>> Andres Freund >>> >>-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20200928/00825801/attachment.html>
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