LLVM Weekly - #213, Jan 29th 2018
Welcome to the two hundred and thirteenth issue of LLVM Weekly, a weekly newsletter (published every Monday) covering developments in LLVM, Clang, and related projects. LLVM Weekly is brought to you by Alex Bradbury. Subscribe to future issues at https://llvmweekly.org and pass it on to anyone else you think may be interested. Please send any tips or feedback to asb@asbradbury.org, or @llvmweekly or @asbradbury on Twitter.
News and articles from around the web
You now have two weeks to submit your proposals for EuroLLVM. Also, registration is now open.
The LLVM Toolchain devroom at FOSDEM will take place next Sunday 4th February. Unfortunately I can't make it to FOSDEM this year, but the devroom has a great line-up thanks to the high quality submissions from the LLVM community.
The next Cambridge LLVM social will take place on Feb 7th 6pm-8pm at the Microsoft Research building.
The next LLVM Social in Paris will be held tomorrow, January 30th. It will feature talks about 'vlang : a C++ RTL simulator and VHDL convertor' and building an LLVM bitcode obfuscator.
The JuliaCon CfP is now open and closes on April 30th. JuliaCon will be held August 7th-11th in London, UK. LLVM-related talks are very welcome.
On the mailing lists
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Peter Collingbourne has written up an RFC on using link-time optimization to eliminate retpolines.
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Greg Clayton started a discussion about how to deal with demangling huge symbols slowing down LLDB. His example symbol de-mangles to something that is 72MB in size and takes 280 seconds.
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Marshall Clow reminds us that a number of components will be removed from
std::experimentalin libcxx in just a few days. -
Peter Smith has provided a mini guide on adding a new target to LLD.
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John Reagan has posted a detailed RFC on improving x86-64 compact unwind descriptors.
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Tom Tromey is looking for feedback on plans for adding Rust language support to LLDB.
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Don Hinton has written an RFC on re-organising the handling of CMake policies.
LLVM commits
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Support for the 'retpoline' mitigation against Spectre on x86 has been merged. r323155.
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New documentation has been added on adding exception handling support for a target. r323311.
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A new utility has been written which uses bugpoint to reduce failures in GlobalISel tests. r323248.
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The AggressiveInstCombine pass has been introduced. This differs from InstCombine in that it can contain optimisations with greater than O(1) complexity. r323321.
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A series of refactoring patches have enabled false dependencies for X86 POPCNT, LZCN and TZCNT to be broken. r323096.
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llvm-extract gained support for extracting a basic block from a function. r323266.
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SelectionDAGISel now prints the current node before calling select, meaning targets don't have to add this logic themselves. r323551.
Clang commits
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The
-fexperimental-iseldriver option can be used to enable/disable GlobalISel. r323485. -
clangd gained a helper to report estimated memory usage per-file. r323425.