[LLVMdev] LLVM Weekly - #83, Aug 3rd 2015

[Alex Bradbury]

LLVM Weekly - #83, Aug 3rd 2015
===============================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/83>.

Welcome to the eighty-third 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

The CodeChecker static analysis infrastructure built on Clang Static Analyzer
[has been released](https://github.com/Ericsson/codechecker). The
[slides](http://llvm.org/devmtg/2015-04/slides/Clang_static_analysis_toolset_final.pdf)
from the talk at EuroLLVM earlier this year give a good overview.

LLVM/Clang 3.7 RC2 [has been
tagged](http://article.gmane.org/gmane.comp.compilers.clang.devel/44237). Time
to get testing.

The implementation of the [Picon](https://github.com/anssi-fr/picon) Control
Flow Integrity protection mechanism has been released. See also the associated
paper [Picon: Control Flow Integrity on LLVM
IR](https://www.sstic.org/media/SSTIC2015/SSTIC-actes/control_flow_integrity_on_llvm_ir/SSTIC2015-Article-control_flow_integrity_on_llvm_ir-fontaine_chifflier_coudray_esfrDAl.pdf).


## On the mailing lists

* There is a plan to [jump to Windows 7 as the baseline requirement for
LLVM](http://article.gmane.org/gmane.comp.compilers.llvm.devel/88947), which
has been featured in LLVM Weekly previously many months ago. If such a move
would cause a problem for you, now is the time to speak up. There's also a
proposal to [drop support for the old mingw.org
toolchains](http://article.gmane.org/gmane.comp.compilers.llvm.devel/88959) in
favour of the maintained mingw-w64.

* James Molloy has prototyped [LoopEditor](http://reviews.llvm.org/D11530), a
high-level API for loop transformations in LLVM and is [seeking additional
feedback](http://article.gmane.org/gmane.comp.compilers.llvm.cvs/260989). The
hope is that existing loop transformations could be rewritten and simplified
to use it.

* Easwaran Raman has shared an [RFC on speedup estimation for inlining cost
analysis](http://article.gmane.org/gmane.comp.compilers.llvm.devel/88929). The
idea is that the estimated speedup (reduction in dynamic instruction count)
from performing the inlining should be used as part of the cost metric.

* Chris Bieneman has penned a [CMake in LLVM
roadmap](http://article.gmane.org/gmane.comp.compilers.llvm.devel/88859) and
[July CMake
update](http://article.gmane.org/gmane.comp.compilers.llvm.devel/88858).
There's even [hope the autoconf build system might be marked deprecated before
the 3.8
branch](http://article.gmane.org/gmane.comp.compilers.llvm.devel/88906).

* Peter Collingbourne has shared a [proposal for arbitrary relocations in
constant global
initialisers](http://article.gmane.org/gmane.comp.compilers.llvm.devel/88856).

* Try not to panic, but the LLVM mailing lists [will be down on August
4th](http://article.gmane.org/gmane.comp.compilers.llvm.devel/88811) as they
will be moving off the UIUC servers. Additionally, SVN access will be
read-only and the LLVM bugzilla will be down.

* Mehdi Amini has issued a [helpful notice for out-of-tree
maintainers](http://article.gmane.org/gmane.comp.compilers.llvm.devel/88793)
on the removal of RegisterScheduler::setDefault.

* Lang Hames has written a [whirlwind introduction to implementing lazy
JITting support for a new architecture in
Orc](http://article.gmane.org/gmane.comp.compilers.llvm.devel/88773).

* Michael Schlottke-Lakemper kicked off a discussion on the possibility of
[using lldb.so to create a stack
trace](http://article.gmane.org/gmane.comp.debugging.lldb.devel/7802).
Respondents pointed out a number of possible choices, including using the
`llvm::sys::printStackTrace()` function.


## LLVM commits

* A new exception handling representation has been introduced for MSVC
compatibility. The commit includes the appropriate updates to the LLVM
language reference. [r243766](http://reviews.llvm.org/rL243766).

* A test to check bitcode compatibility has been added. This will help ensure
the bitcode format produced by an X.Y release is readable by the following X.Z
releases. [r243779](http://reviews.llvm.org/rL243779).

* The lli documentation has been updated and now better explains its purpose.
[r243401](http://reviews.llvm.org/rL243401).

* LLVM gained a target-independent thread local storage (TLS) implementation.
[r243438](http://reviews.llvm.org/rL243438).

* A `reverse(ContainerTy)` range adapter was added.
[r243581](http://reviews.llvm.org/rL243581).


## Clang commits

* The method for emitting metadata for loop hint pragmas has been modified,
using CGLoopInfo. [r243315](http://reviews.llvm.org/rL243315).

* Clang learned to pass `-Wa,-mfpu`, `-Wa,-mhwdiv`, and `-Wa,-mcpu` to the
integrated assembler. [r243353](http://reviews.llvm.org/rL243353).

* Initial support for Open MP 4.1's extended ordered clause was added.
[r243635](http://reviews.llvm.org/rL243635).


## Other project commits

* lldb is starting to gain support for indicating when you are debugging a
function that has been optimized. [r243508](http://reviews.llvm.org/rL243508).