libcxx
abseil-cpp
libcxx | abseil-cpp | |
---|---|---|
14 | 54 | |
677 | 13,955 | |
- | 1.3% | |
0.0 | 9.5 | |
over 4 years ago | 8 days ago | |
C++ | C++ | |
Apache License 2.0 | Apache License 2.0 |
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
libcxx
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Quants use Rust; Devs use C++ - Hey, it's a compromise!
If you are comparing hoops that library authors need to jump through in both languages, you can easily make the real-world comparison in the other direction, by comparing Rust's Option with C++'s std::optional (an exercise left for the reader): Rust std: https://github.com/rust-lang/rust/blob/master/library/core/src/option.rs libcxx: https://github.com/llvm-mirror/libcxx/blob/master/include/optional
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My favorite prime number generator
My favorite prime number generator is the undocumented __next_prime():
https://github.com/llvm-mirror/libcxx/blob/78d6a7767ed57b501...
There is no good reason to use this one except in a code golf environment that includes all headers by default, which is where I learned about it.
- Please can someone tell me where I can find the content of the STL
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"My Reaction to Dr. Stroustrup’s Recent Memory Safety Comments"
I once read a Strousroup quote amounting to "If you understand std::vector, then you understand C++". I thought surely he couldn't have meant the interface but the implentation, googled that llvm's implementation is considered nice and clean, had a look, and noped straight out of there.
- pmr implementation in c++14
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In Defense of Linked Lists
C++'s STL linked list for comparison (libcxx).
https://github.com/llvm-mirror/libcxx/blob/master/include/li...
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RFC: C++ Buffer Hardening
> For example, accessing a std::span or a std::vector outside of its bounds would abort the program, and so would accessing an empty std::optional.
I don't really understand the difference with libc++, libstdc++ and msvc stl's respective debug modes, they already do exactly these checks :
- https://github.com/llvm-mirror/libcxx/blob/78d6a7767ed57b501...
- https://github.com/gcc-mirror/gcc/blob/966010b2eb4a4c52f139b...
- Why is std::array implemented as a struct instead of a class?
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C++ Concurrency Model on x86 for Dummies
I mean it's not hard to read the source for your platform. On Linux/x86_64/libc++ it's roughly:
- https://github.com/llvm-mirror/libcxx/blob/master/include/__...
- https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=nptl/...
I don't particularly care to comb through it to see if anything has changed, but historically it was a a little spin-CAS to make the non-contended path fast and then dropping into a https://en.wikipedia.org/wiki/Futex, which is about as good as it gets for staying mostly in userspace but still letting it be scheduler aware so you're not burning up a core busy-polling, which is what often happens when people try to roll their own shit.
Google wants a bit more latitude on the heuristics and degrees of freedom around read/write ownership, so they did it like this: https://github.com/abseil/abseil-cpp/blob/master/absl/synchr... which is quite a bit better commented/legible.
If anyone reading this can do better than the `abseil-cpp` folks, not only would Google take their PR, they'd probably offer them a job.
- Intrusive List Advantages?
abseil-cpp
- Sane C++ Libraries
- Open source collection of Google's C++ libraries
- Is Ada safer than Rust?
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Appending to an std:string character-by-character: how does the capacity grow?
Yeah, it's nice! And Abseil does it, IFF you use LLVM libc++.
https://github.com/abseil/abseil-cpp/blob/master/absl/string...
The standard adopted it as resize_and_overwrite. Which I think is a little clunky.
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Shaving 40% Off Google’s B-Tree Implementation with Go Generics
This may be confusing to those familiar with Google's libraries. The baseline is the Go BTree, which I personally never heard of until just now, not the C++ absl::btree_set. The benchmarks aren't directly comparable, but the C++ version also comes with good microbenchmark coverage.
https://github.com/google/btree
https://github.com/abseil/abseil-cpp/blob/master/absl/contai...
- Faster Sorting Beyond DeepMind’s AlphaDev
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“Once” one-time concurrent initialization with an integer
An implementation of call_once that accommodates callbacks that throw: https://github.com/abseil/abseil-cpp/blob/master/absl/base/c...
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[R] AlphaDev discovers faster sorting algorithms
I wouldn't say it's that cryptic. It's just a few bitwise rotations/shifts/xor operations.
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Deepmind Alphadev: Faster sorting algorithms discovered using deep RL
You can see hashing optimizations as well https://www.deepmind.com/blog/alphadev-discovers-faster-sort..., https://github.com/abseil/abseil-cpp/commit/74eee2aff683cc7d...
I was one of the members who reviewed expertly what has been done both in sorting and hashing. Overall it's more about assembly, finding missed compiler optimizations and balancing between correctness and distribution (in hashing in particular).
It was not revolutionary in a sense it hasn't found completely new approaches but converged to something incomprehensible for humans but relatively good for performance which proves the point that optimal programs are very inhuman.
Note that for instructions in sorting, removing them does not always lead to better performance, for example, instructions can run in parallel and the effect can be less profound. Benchmarks can lie and compiler could do something differently when recompiling the sort3 function which was changed. There was some evidence that the effect can come from the other side.
For hashing it was even funnier, very small strings up to 64 bit already used 3 instructions like add some constant -> multiply 64x64 -> xor upper/lower. For bigger ones the question becomes more complicated, that's why 9-16 was a better spot and it simplified from 2 multiplications to just one and a rotation. Distribution on real workloads was good, it almost passed smhasher and we decided it was good enough to try out in prod. We did not rollback as you can see from abseil :)
But even given all that, it was fascinating to watch how this system was searching and was able to find particular programs can be further simplified. Kudos to everyone involved, it's a great incremental change that can bring more results in the future.
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Backward compatible implementations of newer standards constructs?
Check out https://abseil.io. It offers absl::optional, which is a backport of std::optional.
What are some alternatives?
STL - MSVC's implementation of the C++ Standard Library.
Folly - An open-source C++ library developed and used at Facebook.
kc85.zig - A KC85 emulator written in Zig
Boost - Super-project for modularized Boost
pacman.zig - Simple Pacman clone written in Zig.
spdlog - Fast C++ logging library.
lion - Where Lions Roam: RISC-V on the VELDT
Qt - Qt Base (Core, Gui, Widgets, Network, ...)
gcc
EASTL - Obsolete repo, please go to: https://github.com/electronicarts/EASTL
nft_ptr - C++ `std::unique_ptr` that represents each object as an NFT on the Ethereum blockchain
BDE - Basic Development Environment - a set of foundational C++ libraries used at Bloomberg.