[llvm-dev] LLVM Weekly - #158, Jan 9th 2017
Alex Bradbury via llvm-dev
llvm-dev at lists.llvm.org
Mon Jan 9 02:51:52 PST 2017
LLVM Weekly - #158, Jan 9th 2017
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Welcome to the one hundred and fifty-eighth 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](http://asbradbury.org). Subscribe to future issues at
<http://llvmweekly.org> and pass it on to anyone else you think may be
interested. Please send any tips or feedback to <asb at asbradbury.org>, or
@llvmweekly or @asbradbury on Twitter.
## News and articles from around the web
John Regehr has written up a really helpful [tourist's guide to the LLVM
The Alive tool for proving the correctness of peephole optimisations is [now
The program for the [LLVM performance workshop at
been announced. It will take place on Saturday February 4th in Austin, Texas.
The next LLVM social in Paris has been
for January 17th. It will feature a talk on the interactions between Polly and
other LLVM passes.
Shahar Mike has written up a brief [tutorial on using libclang to parse
## On the mailing lists
* Rui Ueyama shares a [major milestone for
has successfully been used to link the entirety of the FreeBSD/amd64 base
* The branch for the upcoming 4.0.0 release will take place [on Thursday the
12th of January](lists.llvm.org/pipermail/llvm-dev/2017-January/108696.html).
* Richard Smith
that Clang should not delete null-pointer checks based on
`__attribute__((nonnull))` on libc functions like memcpy. A
message provides further justification.
* Davide Italiano has re-summarised and updated his [proposal for fixing
sparse conditional constant propagation in the presence of
* Alex Denisov has shared some [initial results from a new LLVM-based mutation
* Sanjoy Das has posted an RFC on [allowing readnone and readonly functions to
There seems to be support for this proposal to separate the concepts of
unwindability and memory effects, though lots of discussion on the details.
* Chandler Carruth has proposed [adding gmock to LLVM's unittest
There seems to be support for this so far, and Chandler has [summarised the
remaining details to be
* Peter Smith has shared an RFC on [supporting range extension thinks in
LLD](http://lists.llvm.org/pipermail/llvm-dev/2017-January/108676.html). As he
helpfully explains, these are code sequences generated to compensate for the
limited range of branch immediate operands. A number of the thread responses
discuss the computational complexity of calculating an optimal thunk
## LLVM commits
* MetadataLoader will now load metadata lazily. This reduces the link time of
the 'opt' binary with ThinLTO and debug info enabled from 282s to 224s.
* The packing of the DwarfDebugLine::Row struct has been optimized from
32-bytes to 24-bytes on 64-bit. [r290931](http://reviews.llvm.org/rL290931).
* The PriorityWorklist in LLVM's ADT library gained support for bulk
* The in-tree copy of googletest has been updated to 1.8.0.
* TargetTransformInfo's getAddressComputationCost can now take a scalar
evolution object. This allows TTI to determine whether a given strided access
is complex or not. [r291106](http://reviews.llvm.org/rL291106).
* A new WebAssembly pass has been added which replaces bitcasted function
addresses with wrappers to replace the bitcasts.
## Clang commits
* Support for the AVR target was added to Clang.
* The `-Wtautological-overlap-compare` warning will now fire in more cases.
## Other project commits
* A new benchmark, XSBench was added to the LLVM test suite. This is the first
of what intends to be a series of benchmarks imported from the US Department
of Energy 'proxy' applications.
* Support for building libc++ without an ABI library (such as libc++abi) has
been fixed. [r290849](http://reviews.llvm.org/rL290849).
* The libc++ threading support API has been documented.
* LLD's `--reproduce` can now produce a .tar archive instead of cpio.
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