[llvm-dev] LLVM Weekly - #240, August 6th 2018

[Alex Bradbury via llvm-dev]

LLVM Weekly - #240, August 6th 2018
===================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/240>.

Welcome to the two hundred and fortieth 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 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

LLVM 7.0.0 rc1 [has been
tagged](http://lists.llvm.org/pipermail/llvm-dev/2018-August/125058.html).
Release blockers are
[tracked here](https://bugs.llvm.org/show_bug.cgi?id=38406).

Rust 1.28 was
[released](https://blog.rust-lang.org/2018/08/02/Rust-1.28.html).


## On the mailing lists

* Amara Emerson has shared an [update on GlobalISel design and
goals](http://lists.llvm.org/pipermail/llvm-dev/2018-July/124917.html).
Compile time performance remains withing 5% of FastISel.

* Greg Bedwell has
[shared](http://lists.llvm.org/pipermail/llvm-dev/2018-August/125043.html)
materials from EuroLLVM describing the DExTer tool for tracking debuginfo
quality and updated on its status.

* Raphael Isemann
[shares](http://lists.llvm.org/pipermail/lldb-dev/2018-August/014004.html)
that nightly LLDB benchmarks and flame graphs are now available.

* Sergey Dmitriev posted an RFC to [allow dropping OpenMP offload targets at
link time](http://lists.llvm.org/pipermail/cfe-dev/2018-July/058670.html).

* Rodrigo Caetano Rocha is [seeking
feedback](http://lists.llvm.org/pipermail/llvm-dev/2018-August/125027.html) on
a new proposed function merging optimisation.

* Paul Robinson
[announces](http://lists.llvm.org/pipermail/llvm-dev/2018-August/125068.html)
that preliminary DWARFv5 support is in Clang/LLVM 7.0.

* There has been a large amount of new discussion regarding support for
variable-length vectors. Bruce Hoult shares his [expectation of how RISC-V
vector support will end
up](http://lists.llvm.org/pipermail/llvm-dev/2018-July/124947.html) while
Robin Kruppe
[clarifies](http://lists.llvm.org/pipermail/llvm-dev/2018-July/124980.html)
that there are really two notions of vector length throughout these
discussions.


## LLVM commits

* Profile loading functionality for XRay was implemented.
[r338825](https://reviews.llvm.org/rL338825).

* Pseudo-iterator adaptors implementing 'early increment' style loops were
added to LLVM's ADT library. [r338955](https://reviews.llvm.org/rL338955).

* The MachineOutliner for AArch64 learned to save LR to a register rather than
the stack. [r338278](https://reviews.llvm.org/rL338278).

* llvm-mca documentation was extended to describe the instruction flow.
[r338319](https://reviews.llvm.org/rL338319).

* Rudimentary C++11 support was added to the MS demangler.
[r338324](https://reviews.llvm.org/rL338324).

* A very subtle miscompile due to a bug in EFLAGS copy lowering for X86 was
fixed. Chandler suggests maintainers of out-of-tree branches using the X86
backend may want to cherry-pick this fix.
[r338481](https://reviews.llvm.org/rL338481).

* The Hexagon backend will now simplify the control-flow graph after atomic
expansion. [r338774](https://reviews.llvm.org/rL338774).

* Assembler/disassembler support for Arm SVE is now complete.
[r338261](https://reviews.llvm.org/rL338261).


## Clang commits

* Support for a new implicit conversion sanitizer was added.
[r338288](https://reviews.llvm.org/rL338288).

* Clang learned to support the `[[clang::lifetimebound]]` attribute. This
indicates the lifetime of a function result is related to one of the function
arguments. [r338464](https://reviews.llvm.org/rL338464).

* Clang's ABI lowering for composite types on AArch64 and ARM was adjusted to
match GCC and the AAPCS. [r338279](https://reviews.llvm.org/rL338279).


## Other project commits

* LLDB now supports syntax highlighting, meaning ANSI color escape sequences
are emitted with printed source code.
[r338662](https://reviews.llvm.org/rL338662).

* Support for weighted mutation leveraging was aded to libFuzzer, which gives
mutations weight based on how much new coverage they provide.
[r338776](https://reviews.llvm.org/rL338776)

* String conversions for integral types, `<charconv>`, was added to libcxx.
[r338479](https://reviews.llvm.org/rL338479).