[llvm-dev] LLVM Weekly - #84, Aug 10th 2015

Alex Bradbury via llvm-dev llvm-dev at lists.llvm.org
Mon Aug 10 05:34:43 PDT 2015

LLVM Weekly - #84, Aug 10th 2015

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Welcome to the eighty-fourth 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

Adrian Sampson has written a fantastic [introduction to
LLVM](http://adriansampson.net/blog/llvm.html). It's titled LLVM for Grad
Students, but it should be useful for anybody looking to use LLVM or just
wanting to understand it better.

Brandon Holt has written up a short and helpful post giving [hints and tips on

The move of the mailing lists from UIUC on to lists.llvm.org is now complete.
All public LLVM-related mailing lists [are shown
here](http://lists.llvm.org/cgi-bin/mailman/listinfo). List addresses have now
changed to listname at lists.llvm.org.

There's been some exciting activity in the world of GCC. Support for the draft
C++ Concepts TS [has been
A draft of the technical specification is [available
Additionally, Nick Clifton has posted a useful summary of [GNU toolchain
developments for

## On the mailing lists

* Rong Xu has shared an [RFC for late instrumentation in
LLVM](http://lists.llvm.org/pipermail/llvm-dev/2015-August/089044.html). The
RFC describes (and quantifies) the performance cost of inserting
instrumentation for profile-guided optimisation in the frontend and proposes
approaches for adding instrumentation in the middle-end instead.

* Jingyue Wu kicked off a discussion about [modifying the BasicAA alias
analysis to understand whether there is aliasing between different address

* Teresa Johnson has posted RFCs for the [ThinLTO file API and data
and the [ThinLTO file

* Chandler Carruth is looking to enable the GlobalModsRef in the default pass
pipeline. He's found it performance neutral in his tests so far, but would
[appreciate more people to try and benchmark

* Asking for advice on how to get started with LLVM is very common. Few take
as much time on detailing their background, motivations, and proposed plan as
[Arno Bastenhof in a recent
Probably because of this, his request has attracted some very high quality

## LLVM commits

* A handy new LLVM Support header was introduced. The TrailingObjects template
class abstracts away `reinterpret_cast`, pointer arithmetic, and size
calculation needed for the case where a class has some other objects appended
to the end of it. [r244164](http://reviews.llvm.org/rL244164).

* Initial documentation for the Machine IR serialization format has been
written. [r244292](http://reviews.llvm.org/rL244292).

* Uniquable DICompilerUnits have been disallowed. Old bitcode will be
automatically upgraded and the sed script in the commit message should be
useful for updating out-of-tree testcases.

* All of the TargetTransformInfo cost APIs now use int rather than unsigned.

## Clang commits

* A new checker for code-level localizability issues on OSX/iOS was born. It
will warn about the use of non-localized NSStrings passed to UI methods and
about failing to include a comment in NSLocalizedString macros.

* New AST matchers have been introduced for constructors that are default,
copy, or move. [r244036](http://reviews.llvm.org/rL2440236).

## Other project commits

* The old COFF linker in LLD has been removed in favour of the new, faster,
and simpler implementation. [r244226](http://reviews.llvm.org/rL244226).

* ThreadSanitizer is now enabled for AArch64.

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