llvm dev - Mar 2018 - LLVM Weekly - #218, Mar 5th 2018

LLVM Weekly - #218, Mar 5th 2018
===============================
If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/218>.

Welcome to the two hundred and eighteenth 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 6.0.0 final has [been
tagged](http://lists.llvm.org/pipermail/llvm-dev/2018-March/121520.html) and
will be released shortly.

The program for the EuroLLVM'18 Developers' Meeting has [been
announced](http://blog.llvm.org/2018/03/eurollvm18-developers-meeting-program.html).


## On the mailing lists

* Sanjay Patel triggered a long discussion on [simplifying floating point
operations with an undef
operand](http://lists.llvm.org/pipermail/llvm-dev/2018-February/121444.html).
Chris Lattner posted a
[summary](http://lists.llvm.org/pipermail/llvm-dev/2018-March/121509.html) of
concerns around signalling NaNs in LLVM IR. The discussion proceeded
productively after that, pointing out that [sNaNs raise an invalid flag, but
don't have to
trap](http://lists.llvm.org/pipermail/llvm-dev/2018-March/121569.html).

* Andrea Di Biagio shared an RFC on
[llvm-mca](http://lists.llvm.org/pipermail/llvm-dev/2018-March/121490.html), a
static performance analysis tool capable of estimating performance for a given
sequence of machine code. It's received lots of positive feedback, and the
thread is well worth a read.

* In response to a question, Peter Smith has [summarised the status of Arm LLD
support](http://lists.llvm.org/pipermail/llvm-dev/2018-February/121426.html).

* Marc-André Laperle
[started](http://lists.llvm.org/pipermail/cfe-dev/2018-February/057007.html) a
discussion about cquery vs clangd.


## LLVM commits

* The `update_cc_test_checks.py` utility has been added, which can be used to
update LLVM IR in C/C++ FileCheck test files.
[r326591](http://reviews.llvm.org/rL326591).

* COPY source forwarding in MachineCopyPropagation has been re-enabled.
[r326208](http://reviews.llvm.org/rL326208).

* A new `-disable-gisel-legality-check` command line option has been added,
intended to be used in early stages of porting.
[r326396](http://reviews.llvm.org/rL326396).

* The SystemZ backend gained support for the stackmap and patchpoint
intrinsics. [r326611](http://reviews.llvm.org/rL326611).


## Clang commits

* Initial ('naive') support for cross translation unit analysis with the
Clang
Static Analyzer has been added. [r326323](http://reviews.llvm.org/rL326323).

* The flags `-fforce-enable-int128` and `-fno-force-enable-int128` were added
to 'force' support for `__int128_t` and `__uint128_t` for a target.
[r326045](http://reviews.llvm.org/rL326045).

* A heuristic was added so the static analyzer skips yacc/bison-generated
files. [r326135](http://reviews.llvm.org/rL326135).


## Other project commits

* Initial PPC64 instruction emulation landed in LLDB.
[r326224](http://reviews.llvm.org/rL326224).

* Support was added for building compiler-rt for RISC-V RV32 and RV64.
[r326420](http://reviews.llvm.org/rL326420).

* lld now accepts both `--foo bar` and `--foo=bar` command line option styles.
[r326506](http://reviews.llvm.org/rL326506).