For full conference details, see the website: http://llvm.org/devmtg/2019-10/

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Roundtables [clear filter]
Tuesday, October 22


Round Tables:

MLIR meets
LLVM MLIR (Multi-Level IR) has been recently accepted as a sub-project in LLVM. Let's talk about what it means, what are the opportunities for LLVM users, and future evolution for the project.
Mehdi Amini, Jacques Pienaar, Tatiana Shpeisman

Well-defined C++ APIs for LLVM libraries
This Round Table is for users of the LLVM C++ APIs. We will discuss next steps for formalizing the C++ APIs within LLVM, how to reduce the number of symbols exported by LLVM shared libraries, the feasibility of a stabilizing parts of the API and other related topics.
Tom Stellard

Tuesday October 22, 2019 10:20am - 11:30am
Round Tables (LL21EF)


Round Tables:

Discuss llvm-libc
A good number of people have expressed interest in llvm-libc during the discussion on the RFC thread. We would like to get everyone interested in this new project to get together and discuss the direction in which we would like to take it forward.
Siva Chandra

VPlan: Next Steps
There are a number of features people are working on and we need to make sure we don't duplicate efforts and have a common understanding of the overall design.

sourcekit-lsp and clangd
Discuss topics related to implementing the language server protocol, code indexing, editor support, build system integration, etc. in clangd and sourcekit-lsp.
Ben Langmuir

Debug Info for optimized code
Do you want to discuss implementation details for representing optimized code debug info? Do you have a question about LiveDebugValues? Do you wonder what's up with entry values? Or do you just wonder how to make your pass debug-info invariant?
Adrian Prantl

Tuesday October 22, 2019 11:30am - 12:40pm
Round Tables (LL21EF)


Round Tables:

Discuss flang, old flang, and Fortran
Steve Scalpone

Tuesday October 22, 2019 2:00pm - 3:10pm
Round Tables (LL21EF)


Round Tables:

Improving LLVM's buildbot instance
http://lab.llvm.org:8011/console is a mess. It has too many builders, yet is missing builders for some platforms. It's slow to load, many of the builders are perma-red, many take hours to cycle, the buildbot page itself is slow to load, etc. Can we improve this?
Nico Weber, Hans Wennborg

OpenMP in LLVM
Opportunity to discuss anything OpenMP related that happens under the LLVM umbrella
Johannes Doerfert, Alexey Bataev, Ravi Narayanaswamy

Challenges using LLVM for GPU compilation
- Canonicalization vs. GPUs: Type mutation
- Control flow mutation (and that graphics shaders are more sensitive to this.)
- Divergence/reconvergence sensitivity
- Address-space awareness
Anastasia Stulova

End-to-end Testing
Discussion of end-to-end testing; what kinds of tests we want; logistics
David Greene

Security Hardening Features in clang
We will discuss the status of security hardening features in clang, (e.g. -fstack-clash-protection, -D_FORTIFY_SOURCE, and others) look at how clang compares to gcc and talk about future work in this area.
Tom Stellard

LLVM for Embedded Baremetal Targets
We will discuss how to build and test LLVM based toolchains that work for Baremetal targets.
Hafiz Abid Qadeer

Tuesday October 22, 2019 3:10pm - 4:20pm
Round Tables (LL21EF)



Let's talk about SYCL -- the programming model, the open standard, the effort to add SYCL support to clang, etc.
Alexey Bader

Upstreaming SYCL C++
SYCL is a single-source C++ standard from Khronos Group (OpenGL, Vulkan, OpenCL, SPIR...) for heterogeneous computing targeting various accelerators (CPU, GPU, DSP, FPGA...). There are several implementations available and one has even started to be upstreamed into Clang/LLVM: https://github.com/intel/llvm
This is a huge collaborative effort and a great opportunity to have wide & strong support for modern C++ on a wide range of accelerators from many vendors. Come to learn about SYCL, how to help reviewing the patches, how it interacts with existing off-loading support, OpenMP, OpenCL, CUDA, address spaces, SPIR-V...
Alexey Bader, Ronan Keryell

Loop Optimizations in LLVM
Discuss current problems, progress and future plans for optimizing loops, existing passes and new passes and analysis being worked on.
Kit Barton, Michael Kruse

full restrict support in llvm
Now that patches for full restrict are available, this roundtable gives a chance to discuss the design and the patches in person.
Jeroen Dobbelaere

Tuesday October 22, 2019 4:40pm - 5:50pm
Round Tables (LL21EF)


Round Tables TBD

Tuesday October 22, 2019 5:50pm - 6:20pm
Round Tables (LL21EF)
Wednesday, October 23



Complex Types in LLVM
A discussion on supporting native complex types in LLVM IR for performance and diagnostics.
David Greene, Stephen Neuendorffer

Development practices to help avoid security vulnerabilities in llvm
The goal for this round table is to explore what development practices the LLVM community could consider adopting to reduce the probability of security vulnerabilities in some or all of its components.
Let's get together at this round table to discuss which development practices - and to which degree - could be good to adopt for which LLVM components. A few examples that could kick off the discussion are:
• Using static analyzers.
• Using code standard checkers (e.g. clang-tidy -checks=cert-*,bugprone-*,llvm-*).
• Using fuzzers more extensively (oss-fuzz does fuzzing on some LLVM components, but do bug reports get reacted on?).
• Requiring full code coverage by unit tests on code that is newly added.
• Making certain build options on by default (e.g. stack protection).
Many of these techniques require buy-in from the whole community to get accepted - a round-table discussion is hopefully a first step towards understanding cost/benefit tradeoffs.
Kristof Beyls

CMake in LLVM
Discuss the current state of CMake and future areas for improvement.
Tom Stellard, Chris Bieneman

Wednesday October 23, 2019 10:45am - 11:55am
Round Tables (LL21EF)



Interpreting C++
C++ JITs and REPLs are useful in number of areas such as education and science. The LLDB's expression evaluator, Cling and ClangJIT are based on Clang and its incremental processing facility. The C++ interpreters target to solve different sets of issues, however they share common requirements.
We would like to use the round table to discuss common requirements when interpreting C++. We would like to invite developers and users interested in interpreting C++. We would like to discuss a possible way forward for implementing JIT and REPL support infrastructure in Clang and LLVM.
Vassil Vassilev, Hal Finkel

LLVM Releases
Discuss the current release process and possible areas for improvement.
Tom Stellard, Hans Wennborg

Vector Predication
Support for predicated SIMD/vector in LLVM is lacking. At this table, we are discussing concrete steps to change that. Topics include:

- LLVM-VP proposal (https://reviews.llvm.org/D57504)
- Intersection with constrained-fp intrinsics and backend support (also
complex arith).
- Design of predicated reduction intrinsics (intersection with
- Compatibility with SVE LLVM extension.
- <Your topic here>"
Simon Moll

Wednesday October 23, 2019 11:55am - 12:30pm
Round Tables (LL21EF)



Floating point
Discussions related to FENV_ACCESS support, fast math, FMA, complex, etc.
Andy Kaylor

Building the Linux kernel with Clang and LLVM utils
Nick Desaulniers

Wednesday October 23, 2019 1:45pm - 2:55pm
Round Tables (LL21EF)



GitHub Next-step: bug-tracker (GitHub issues?) & workflows (pre-merge testing, pull-request, etc.)
We're almost on GitHub! It is a good opportunity to brainstorm on possible evolutions of the workflow and the infrastructure. There are opportunities around being able to run builds and test on code before pushing, and the possibility of using pull-requests either for the purpose of pre-merge testing or for code reviews!
Also is bugzilla still providing what we want to track issues? Should we consider GitHub issues? Are there other options?
Christian Kühnel, Dmitri Gribenko, Kristof Beyls, Mehdi Amini

Discuss future work and direction of ASTImporter
Gabor Marton

State of the GN build
LLVM's GN build is an (unsupported!) faster alternative to the CMake build. Try it out, learn about the current state, wallow in build system arcana.
Nico Weber

Clang Static Analyzer
Let's talk about where we are and how we want to move forward with the Static Analyzer.
Artem Dergachev

Scalable Vector Extension
Discuss current progress and forward plans for both SVE and RiscV implementations, focusing on agreed IR representations more than looking at each back-end independently.

Wednesday October 23, 2019 2:55pm - 4:00pm
Round Tables (LL21EF)



LLVM Google Summer of Code: organization, ideas, projects, etc.
Anton Korobeynikov

Wednesday October 23, 2019 5:00pm - 5:35pm
Round Tables (LL21EF)



Wednesday October 23, 2019 5:35pm - 6:10pm
Round Tables (LL21EF)