Introduce a Cargo feature to enable or disable architecture-specific
features (SIMD, assembly), which is on by default. This allows for more
fine grained control compared to relying on the `force-soft-floats`
feature.
Similar to "unstable-intrinsics", introduce a build.rs config option for
`unstable-intrinsics AND NOT force-soft-floats`, which makes this easier
to work with in code.
Effectively, this allows moving our non-additive Cargo feature
(force-soft-floats) to a positive one by default, allowing for an
override when needed.
We currently have a non-additive feature, "force-soft-floats", and we
will need to gain another "no-f16-f128". This makes `cfg` usage in code
somewhat confusing and redundant.
Use `build.rs` to figure out if "unstable-intrinsics" is enabled while
"force-soft-floats" is not enabled and if so, emit a cfg
`intrinsics_enabled`. This is cleaner to use and should make adding more
features easier to reason about.
Also use this as an opportunity to eliminate the build.rs from the
compiler-builtins test crate, replaced with the `[lints]` table in
Cargo.toml.
Currently there is a single feature called "unstable" that is used to
control whether intrinsics may be called. In anticipation of adding
other unstable features that we will want to control separately, create
a new feature called "unstable-intrinsics" that is enabled by
"unstable". Then move everything gated by "unstable" to
"unstable-intrinsics".
* 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
