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8995ac0448
Get performance closer to the glibc implementations by adding assembly
fma routines, with runtime feature detection so they are used even if
not compiled with `+fma` (as the distributed standard library is often
not). Glibc uses ifuncs, this implementation stores a function pointer
in an atomic.
Results of CPU flags are also cached in order to avoid repeating the
startup time in calls to different functions. The feature detection code
is a slightly simplified version of `std-detect`.
Musl sources were used as a reference [1].
Fixes: https://github.com/rust-lang/rust/issues/140452 once synced
[1]: c47ad25ea3/src/math/x32/fma.c
compiler-builtins and libm
This repository contains two main crates:
compiler-builtins: symbols that the compiler expects to be available at link timelibm: a Rust implementation of C math libraries, used to provide implementations inocre.
More details are at compiler-builtins/README.md and libm/README.md.
For instructions on contributing, see CONTRIBUTING.md.
License
libmmay be used under the MIT Licensecompiler-builtinsmay be used under the MIT License and the Apache License, Version 2.0 with the LLVM exception.- All original contributions must be under all of: the MIT license, the Apache-2.0 license, and the Apache-2.0 license with the LLVM exception.
More details are in LICENSE.txt and libm/LICENSE.txt.