llvm dev - Aug 2021 - LLVM Weekly - #400, August 30th 2021

LLVM Weekly - #400, August 30th 2021
===================================
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<http://llvmweekly.org/issue/400>.

Welcome to the four hundredth 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
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## News and articles from around the web

Phoronix has a [set of
benchmarks](https://www.phoronix.com/scan.php?page=article&item=intel-icelake-clang13)
of Clang 13 on a Xeon Ice Lake machine.


## On the mailing lists

* Arthur Eubanks kicked off an RFC on [deprecating the legacy pass
  manager](https://lists.llvm.org/pipermail/llvm-dev/2021-August/152305.html),
  later clarifying that the proposal was to deprecate and then remove it.
  While there's obviously no support for keeping it around indefinitely,
  there is active discussion about what an appropriate deprecation period
  would be.

* Juneyoung Lee is [seeking
  feedback](https://lists.llvm.org/pipermail/llvm-dev/2021-August/152253.html)
  on patches that enable clang's noundef analysis flag by default, and the
  proposed strategy for handling tests that need updating.

* Serge Pavlov shared an RFC on the [semantics of
 
llvm::isnan](https://lists.llvm.org/pipermail/llvm-dev/2021-August/152257.html),
  explaining the issue with converting `__builtin_isnan` to `cmp uno`.

* Hyeongyu Kim and Deep Majumder shared final reports of their GSoC projects
  on [fixing miscompilation issues in LLVM IR using the freeze
 
instruction](https://lists.llvm.org/pipermail/llvm-dev/2021-August/152286.html)
  and [making smart pointer checkers default checkers in the static
  analyzer](https://lists.llvm.org/pipermail/llvm-dev/2021-August/152275.html).

* Liqiang Tao [proposed adding a module
  inliner](https://lists.llvm.org/pipermail/llvm-dev/2021-August/152297.html).

* LLVM 13.0.0-rc2 [has been
  tagged](https://lists.llvm.org/pipermail/llvm-dev/2021-August/152353.html).

## LLVM commits

* The LoopPeel pass now supports multiple unreachable-terminated exit blocks,
  resulting in a ~20-30% increase in the Geekbench5/HDR score on AArch64.
  [90d09eb3](https://reviews.llvm.org/rG90d09eb300db).

* Graph reordering in the superworld-level parallelism vectorizer was
  improved. [84cbd71](https://reviews.llvm.org/rG84cbd71c9592).

* The getting started with Visual Studio guide was updated.
  [1958575](https://reviews.llvm.org/rG195857585908).

* llvm-reduce learned to remove module data such as data layout, target triple
  etc. [d2e1036](https://reviews.llvm.org/rGd2e103644be3).

* lit gained a new option to force tests to run in lexical order.
  [2f69c82](https://reviews.llvm.org/rG2f69c82cec1a).


## Clang commits

* `#pragma clang restrict_expansion`, which flags macros as unsafe for header
  use, was implemented. [43de869](https://reviews.llvm.org/rG43de869d77f7).

* Support was added to `__attribute__((error("")))` and
  `__attribute__((warning("")))`.
  [846e562](https://reviews.llvm.org/rG846e562dcc6a).

* The bugprone-suspicious-memory-comparison check was added to clang-tidy.
  [3373e84](https://reviews.llvm.org/rG3373e845398b).


## Other project commits

* The LLDB curses UI gained support for a 'searcher' element.
  [3c11e57](https://reviews.llvm.org/rG3c11e5722c30).

* CloudABI support was removed from libc++.
  [87dd519](https://reviews.llvm.org/rG87dd51983cf9).