[llvm-dev] LLVM Weekly - #197, Oct 9th 2017

[Alex Bradbury via llvm-dev]

LLVM Weekly - #197, Oct 9th 2017
================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/197>.

Welcome to the one hundred and ninety-seventh 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 registration deadline for the upcoming [LLVM Dev
Meeting](https://www.eventbrite.com/e/2017-llvm-developers-meeting-bay-area-tickets-35155516095)
has been extended to October 10th, 11:59PM PDT.

Reminder: If you're still in San Jose on Friday 20th October and are
interested in contributing to RISC-V support in LLVM projects, then
[consider signing up to the working
session](https://groups.google.com/a/groups.riscv.org/d/msg/sw-dev/QG8zlSuNf7E/Zc_eWhITBQAJ).

Many more talks from CppCon 2017 are [now available on
YouTube](https://www.youtube.com/playlist?list=PLHTh1InhhwT6bwIpRk0ZbCA0N2p1taxd6).

Slides and videos from the recent GNU Tools Cauldron are [now
online](https://slideslive.com/gnu/gnu-tools-cauldron-2017).


## On the mailing lists

* Tanya Lattner is
[looking](http://lists.llvm.org/pipermail/llvm-dev/2017-October/118023.html)
for help in tagging 'beginner' bugs on bugzilla.

* Should LLD [switch to using --hash-style=both by
default](http://lists.llvm.org/pipermail/llvm-dev/2017-October/117876.html)?
Rui has summarised the [current
plan](http://lists.llvm.org/pipermail/llvm-dev/2017-October/117968.html).

* Matthias Braun is seeking feedback on [merging TargetMachine and
LLVMTargetMachine](http://lists.llvm.org/pipermail/llvm-dev/2017-October/117907.html).


## Review corner

The LLVM Weekly review corner serves to highlight patches that are stuck
waiting awaiting review, or work from first-time contributors. See
[here](http://llvmweekly.org/reviewcorner) for more information and how to
submit you work for inclusion. Of course the hope is that highlighting these
patches will enable LLVM Weekly readers will step up and help to get them
merged. I'll be reporting back each week on any activity generated on these
patches, as well as sharing a new batch. If you want your patch included you
must submit it via the linked form.

Last week featured just one patch. Thanks for Philip Reames for moving that
review forwards.

* "This fixes symbol generation on the exception path for Windows on unnamed
functions. It may avoid crashing the program after applying CloneFunction on
an unnamed function." (Summary lightly copy-edited).
[D37434](https://reviews.llvm.org/D37434), patch by Pierrick Brunet.

* "[analyzer] Better handling of arithmetic calculations. This fixes
<https://bugs.llvm.org/show_bug.cgi?id=32911>."
[D36471](https://reviews.llvm.org/D36471), patch by Daniel Marjamäki.

* "[analyzer] Clarify the warnings when there is undefined behaviour in shift
operations." [D30295](https://reviews.llvm.org/D30295), patch by Daniel
Marjamäki.

I'll be at the LLVM Dev Meeting next week. If you have thoughts on this
'review corner' section I'd be very interested in chatting (is it worth
continuing? How could it be improved? Alternative ideas?).


## LLVM commits

* The ASM parser can now report multiple near misses for an invalid
instruction. This allows the target-specific parser to use heuristics to
choose the mot appropriate error message(s) to print. See the commit message
for more details, as well as the follow-up patch that uses these new
diagnostics for ARM. [r314774](http://reviews.llvm.org/rL314774),
[r314779](http://reviews.llvm.org/rL314779).

* llvm-dwarfdump gained the ability to collect and display debug info quality
metrics. As suggested in the commit message, this functionality might be used
to automatically track debug info quality and highlight any unexpected
regressions. [r315101](http://reviews.llvm.org/rL315101).

* More debug messages have been added to LegalizeDAG.
[r314773](http://reviews.llvm.org/rL314773).

* optimizeMemoryInst in CodeGenPrepare can now handle multiple AddrModes (as
long as they differ in at most one field).
[r314795](http://reviews.llvm.org/rL314795).

* It is now possible to specify an AsmOperand's DiagnosticString in TableGen.
[r314803](http://reviews.llvm.org/rL314803),
[r314804](http://reviews.llvm.org/rL314804).

* The SLPVectorizer will now attempt to vectorize loads of consecutive memory
locations, accessed in a non-consecutive way.
[r314806](http://reviews.llvm.org/rL314806). REVERTED

* The expansion of 64-bit div/rem for AMDGPU has been rewritten to be more
efficient. [r315081](http://reviews.llvm.org/rL315081).


## Clang commits

* Clang now has machinery to support "dependent address spaces", i.e. cases
where the target address space is dependent on a template parameter.
`__attribute__(((address_space(N))))`.
[r314649](http://reviews.llvm.org/rL314649),
[r314650](http://reviews.llvm.org/rL314650).

* The refactoring interface has been simplified.
[r314704](http://reviews.llvm.org/rL314704).


## Other project commits

* If you want to recreate the benchmarks used to evaluate LLD performance, see
this commit for details. [r314682](http://reviews.llvm.org/rL314682).

* Support has been improved for using LLDB to debug FreeBSD kernel modules
[r314672](http://reviews.llvm.org/rL314672).

* It is now possible to create breakpoints and read/write general purpose
registers with LLDB for ppc64le. [r315008](http://reviews.llvm.org/rL315008).