This crate builds math symbols from a musl checkout and provides a Rust
interface. The intent is that we will be able to compare our
implementations against musl on more than just linux (which are the only
currently the only targets we run `*-musl` targets against for
comparison).
Musl libc can't compile on anything other than Linux; however, the
routines in `src/math` are cross platform enough to build on MacOS and
windows-gnu with only minor adjustments. We take advantage of this and
build only needed files using `cc`.
The build script also performs remapping (via defines) so that e.g.
`cos` gets defined as `musl_cos`. This gives us more certainty that we
are actually testing against the intended symbol; without it, it is easy
to unknowingly link to system libraries or even Rust's `libm` itself and
wind up with an ineffective test. There is also a small procedure to
verify remapping worked correctly by checking symbols in object files.
We will have more test features in the near future, and it would be nice
for them all to have a common `test-` prefix. Reverse the existing
feature so this is the case.
There isn't any reason for this feature to be exposed or part of the
build script. Move it to a separate crate.
We will also want more tests that require some support functions; this
will create a place for them.
* Use macros for more division/array checks
This commit moves over more array accesses to the `i!` macro to avoid
bounds checks when debug assertions are disabled. This is surfaced from
rust-lang/compiler-builtins#360 where recent changes in codegen units
has caused some bounds checks to not get elided in release mode. This
also adds a `div!` macro to work around rust-lang/rust#72751.
* Don't test/bench our shim crate
It's not intended to run all our tests
