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Kostya Kortchinsky 419f1a4185 [scudo][standalone] Optimization pass 
Summary:
This introduces a bunch of small optimizations with the purpose of
making the fastpath tighter:
- tag more conditions as `LIKELY`/`UNLIKELY`: as a rule of thumb we
  consider that every operation related to the secondary is unlikely
- attempt to reduce the number of potentially extraneous instructions
- reorganize the `Chunk` header to not straddle a word boundary and
  use more appropriate types

Note that some `LIKELY`/`UNLIKELY` impact might be less obvious as
they are in slow paths (for example in `secondary.cc`), but at this
point I am throwing a pretty wide net, and it's consistant and doesn't
hurt.

This was mosly done for the benfit of Android, but other platforms
benefit from it too. An aarch64 Android benchmark gives:
- before:
```
  BM_youtube/min_time:15.000/repeats:4/manual_time_mean              445244 us       659385 us            4
  BM_youtube/min_time:15.000/repeats:4/manual_time_median            445007 us       658970 us            4
  BM_youtube/min_time:15.000/repeats:4/manual_time_stddev               885 us         1332 us            4
```
- after:
```
  BM_youtube/min_time:15.000/repeats:4/manual_time_mean       415697 us       621925 us            4
  BM_youtube/min_time:15.000/repeats:4/manual_time_median     415913 us       622061 us            4
  BM_youtube/min_time:15.000/repeats:4/manual_time_stddev        990 us         1163 us            4
```

Additional since `-Werror=conversion` is enabled on some platforms we
are built on, enable it upstream to catch things early: a few sign
conversions had slept through and needed additional casting.

Reviewers: hctim, morehouse, eugenis, vitalybuka

Reviewed By: vitalybuka

Subscribers: srhines, mgorny, javed.absar, kristof.beyls, delcypher, #sanitizers, llvm-commits

Tags: #llvm, #sanitizers

Differential Revision: https://reviews.llvm.org/D64664

llvm-svn: 366918
 		2019-07-24 16:36:01 +00:00
..
cmake [libFuzzer] Set Android specific ALL_FUZZER_SUPPORTED_ARCH 2019-07-19 02:07:46 +00:00
docs
…
include [dfsan] Introduce dfsan_flush(). 2019-06-13 20:11:06 +00:00
lib [scudo][standalone] Optimization pass 2019-07-24 16:36:01 +00:00
test [NFC][ASAN] Add brackets around not command 2019-07-23 13:10:29 +00:00
unittests [compiler-rt] Rename lit.*.cfg.* -> lit.*.cfg.py.* 2019-06-27 20:56:04 +00:00
utils Update the ioctl(2) list in sanitizers with NetBSD 8.99.34 2019-02-05 22:20:25 +00:00
www Adjust documentation for git migration. 2019-01-29 16:37:27 +00:00
.arcconfig [compiler-rt] Set up .arcconfig to point to new Diffusion CRT repository 2017-12-06 20:55:32 +00:00
.gitignore Add .pyc files to .gitignore to compiler-rt 2017-07-24 21:51:12 +00:00
CMakeLists.txt [CMake] Don't set Python_ADDITIONAL_VERSIONS 2019-07-18 15:17:42 +00:00
CODE_OWNERS.TXT
…
CREDITS.TXT
…
LICENSE.TXT Fix typos throughout the license files that somehow I and my reviewers 2019-01-21 09:52:34 +00:00
README.txt
…

README.txt 

Compiler-RT
================================

This directory and its subdirectories contain source code for the compiler
support routines.

Compiler-RT is open source software. You may freely distribute it under the
terms of the license agreement found in LICENSE.txt.

================================