| commit | a8ca5d35306a48a81de9939925327de2f948c5eb | [log] [tgz] |
|---|---|---|
| author | Matthias Maennich <[email protected]> | Tue Jun 08 08:29:00 2021 +0100 |
| committer | Matthias Maennich <[email protected]> | Tue Jun 08 11:48:20 2021 +0100 |
| tree | 4baaf608a40c275137564eac30e54524f715f172 | |
| parent | e1d6ee2fab91f83f432493671a434881172c366e [diff] |
strutil: replace SSE4 specialization with libc call SkipUntil had been partially specialized to use SSE4.2 instructions if selected at compile time. The Makefile.ckati sets the compile flags to the rather incompatible -march=native to enable the SSE4.2 instruction set. The minimum (Intel) architecture required for SSE4.2 is Nehalem, so -march=nehalem would do and that would probably make things a bit more compatible when distributing the binary across machines. It turns out, the relevant part of SkipUntil can actually be replaced by a checked `strpbrk` call. Recent libc implementations do specialize strpbrk for SSE4.2 as well. E.g. glibc runtime-selects `__strpbrk_sse42` if the host provides the instruction set. The ckati benchmark `strutil_bench` is neutral to this change. On my machine the benchmark consistently produces around *kati*: WordScanner: 0.156697 with or without the change applied. This is when using the Make based building process that also sets -march=native. Other build systems and processes might not want to use -march=native to be able to produce compatible builds. They might also not want to use any limiting -march=* at all. That is the case for the Android build where ckati is built and mainly used. When building in that environment, the strutil_bench consistently runs *kati*: WordScanner: 0.396514 and when applying this patch *kati*: WordScanner: 0.255683 The difference between the best Android build and the Make based build must be related to other build settings done in the Android/Soong based build, such as FORTIFY_SOURCE, stack protector, etc. Another side effect of this patch is, that we can run the kati test suite successfully with --fsanitize=address now. Otherwise the SSE4.2 specific implementation would cause an address violation due to an out-of-bounds read. Signed-off-by: Matthias Maennich <[email protected]>
kati is an experimental GNU make clone. The main goal of this tool is to speed-up incremental build of Android.
Currently, kati does not offer a faster build by itself. It instead converts your Makefile to a ninja file.
Building:
$ make ckati
The above command produces a ckati binary in the project root.
Testing (best ran in a Ubuntu 18.04 environment):
$ make test $ go test --ckati $ go test --ckati --ninja $ go test --ckati --ninja --all
The above commands run all cKati and Ninja tests in the testcases/ directory.
Alternatively, you can also run the tests in a Docker container in a prepared test enviroment:
$ docker build -t kati-test . && docker run kati-test
For Android-N+, ckati and ninja is used automatically. There is a prebuilt checked in under prebuilts/build-tools that is used.
All Android's build commands (m, mmm, mmma, etc.) should just work.