The `feature_detect` module is currently being built on all targets, but
the use of `AtomicU32` causes a problem if atomics are not available
(such as with `bpfel-unknown-none`). Gate this module behind
`target_has_atomic = "ptr"`.
The below now completes successfully:
cargo build -p compiler_builtins --target=bpfel-unknown-none -Z build-std=core
Fixes: https://github.com/rust-lang/compiler-builtins/issues/908
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
These appeared in a later nightly. In compiler-builtins we can apply the
suggestion, but in `libm` we need to ignore them since `fx::from_bits`
is not `const` at the MSRV.
`clippy::uninlined_format_args` also seems to have gotten stricter, so
fix those here.
Edition 2024 requires that we avoid this. There is a lot of code that
will need to be adjusted, so start the process here with a warning that
will show up in CI.
It would be nice to reuse some of the macro structure for internal
functions, like `rem_pio2`. To facilitate this, add a `public` field and
make it available in the macro's API.
The published crates fail to build with an edition less than 2024
because they are packaged with `resolver = "3"`, which is a 2024-only
option. Revert back to resolver v2 to drop this requirement.
Fixes: https://github.com/rust-lang/compiler-builtins/issues/883
`compiler-builtins` uses `public-test-deps`, `libm` uses
`unstable-public-internals`. Consolidate these under the `libm` name.
Once compiler-builtins is no longer published, this feature can probably
be dropped.
Also switch to `dep:` syntax for features that enable dependencies.
compiler-builtins currently wouldn't publish correctly because of a
relative path to `libm` that doesn't get included in the package. Fix
this by simlinking `libm` to within the `compiler-builtins` directory.
Also symlink LICENSE.txt which lets us drop the `include` array in
Cargo.toml. LICENSE.txt and compiler-rt were not being included anyway,
since Cargo silently drops items that are not within the crate
directory.
In order to disambiguate things now that libm is part of the
compiler-builtins repository, do the following:
* Mention libm in LICENSE.txt
* Clarify the default license for crates other than libm and
compiler-builtins
* Add an explicit license field to Cargo.toml for all other crates
Many contributions to compiler-builtins don't have any need to touch
libm, and could get by with the few minutes of CI for compiler-builtins
rather than the ~30 minutes for libm. We already have some scripts that
handle changed file detection, so expand its use to skip libm CI if it
doesn't need to run.
Set the submodule to the same version we had been using in
rust-lang/libm. This is a downgrade from the current version but it
avoids some new deviations that show up, which can be corrected later.
Update `run.sh` to start testing `libm`. Currently this is somewhat
inefficient because `builtins-test` gets run more than once on some
targets; this can be cleaned up later.
