llvm dev - Feb 2018 - LLVM Weekly - #216, Feb 19th 2018

LLVM Weekly - #216, Feb 19th 2018
================================
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Welcome to the two hundred and sixteenth 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](https://www.linkedin.com/in/alex-bradbury/). Subscribe to future
issues at <http://llvmweekly.org> and pass it on to anyone else you think
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@llvmweekly or @asbradbury on Twitter.


## News and articles from around the web

LLVM has been
[accepted](http://blog.llvm.org/2018/02/llvm-accepted-to-2018-google-summer-of.html)
to Google Summer of Code 2018. Student applications open on March 12th.

Martin Cracauer has written a blog post on [LLVM's garbage collection
facilities and SBCL's generational
GC](https://medium.com/@MartinCracauer/llvms-garbage-collection-facilities-and-sbcl-s-generational-gc-a13eedfb1b31).

The paper [Crellvm: Verified Credible Compilation for
LLVM](http://sf.snu.ac.kr/crellvm/) has been accepted for PLDI 2018, and may
be of interest to many LLVM Weekly readers. The authors present a methodology
for validating optimisations, and apply it to mem2reg and gvn (global value
numbering).

Serge Guelton and Juan Manuel Martinez Caamaño have written
[Easy::jit](https://github.com/jmmartinez/easy-just-in-time), a Just-In-Time
compiler for C++ built using Clang and LLVM.


## On the mailing lists

* Dean Michael Berris has written an RFC on [adding an XRay profiling
mode](http://lists.llvm.org/pipermail/llvm-dev/2018-February/121237.html) to
LLVM, which gathers basic statistics about where time is being spent when
executing a program.

* Galina Kistanova
[announces](http://lists.llvm.org/pipermail/llvm-dev/2018-February/121246.html)
that a new performance builder has been added for LLD, which exports its
results using LNT.

* Philip Reames
[shares](http://lists.llvm.org/pipermail/llvm-dev/2018-February/121268.html)
his observations on currently missing cases where attributes could be
inferred.

* Hans Wennborg
[indicates](http://lists.llvm.org/pipermail/llvm-dev/2018-February/121295.html)
that the 6.0.0 final tag won't be made by the 21st of Feb (as in the
original
release schedule), but the hope is to have rc3 tagged by Friday with [release
blockers](llvm.org/PR35804) fixed.


## LLVM commits

* The width of the GEP (getelemenptr) index used in address calculation can
now be specified using the data layout string.
[r325102](http://reviews.llvm.org/rL325102).

* LLVM will now try harder to report a fatal error when out of memory (when
memory allocation fails). [r325426](http://reviews.llvm.org/rL325426).

* The X86 disassembler now properly decodes old AMD 3DNow! instructions.
[r325295](http://reviews.llvm.org/rL325295).

* The patch that extended MachineCopyPropagation to do COPY source forwarding
has been reverted. [r325421](http://reviews.llvm.org/rL325421).


## Clang commits

* The 'artificial' function attribute is now supported. This controls
debugger
stepping behaviour with respect to inline functions.
[r325081](http://reviews.llvm.org/rL325081).

* clang-tidy gained a new checker for exceptions that are created but not
thrown. [r325222](http://reviews.llvm.org/rL325222).


## Other project commits

* compiler-rt added XRay instrumentation support for FreeBSD and NetBSD.
[r325240](http://reviews.llvm.org/rL325240),
[r325345](http://reviews.llvm.org/rL325345).

* The libcxxabi demangler gained support for new features such as initializer
lists and exception specifications.
[r324970](http://reviews.llvm.org/rL324870),
[r325093](http://reviews.llvm.org/rL325093).

* Parallelism in the LLDB test suite runner has been increased.
[r325322](http://reviews.llvm.org/rL325322).