Silence the approximate constant lint because it is noisy and not always
correct. `single_component_path_imports` is also not accurate when built
as part of `compiler-builtins`, so that needs to be `allow`ed as well.
```text
warning: function `f32_to_bits` is never used
--> libm/src/math/support/float_traits.rs:367:14
|
367 | pub const fn f32_to_bits(x: f32) -> u32 {
| ^^^^^^^^^^^
|
= note: `#[warn(dead_code)]` on by default
warning: function `f64_to_bits` is never used
--> libm/src/math/support/float_traits.rs:381:14
|
381 | pub const fn f64_to_bits(x: f64) -> u64 {
| ^^^^^^^^^^^
warning: `libm` (lib) generated 2 warnings
```
This is a false positive, see RUST-144060.
`i256` and `u256`
- operators now use the same overflow convention as primitives
- implement `<<` and `-` (previously just `>>` and `+`)
- implement `Ord` correctly (the previous `PartialOrd` was broken)
- correct `i256::SIGNED` to `true`
The `Int`-trait is extended with `trailing_zeros`, `carrying_add`, and
`borrowing_sub`.
After adding tests, the current implementation for fminimum fails when
provided a negative zero and NaN as inputs:
---- math::fminimum_fmaximum_num::tests::fmaximum_num_spec_tests_f64 stdout ----
thread 'math::fminimum_fmaximum_num::tests::fmaximum_num_spec_tests_f64' panicked at libm/src/math/fminimum_fmaximum_num.rs:240:13:
fmaximum_num(-0x0p+0, NaN)
l: NaN (0x7ff8000000000000)
r: -0.0 (0x8000000000000000)
---- math::fminimum_fmaximum_num::tests::fmaximum_num_spec_tests_f32 stdout ----
thread 'math::fminimum_fmaximum_num::tests::fmaximum_num_spec_tests_f32' panicked at libm/src/math/fminimum_fmaximum_num.rs:240:13:
fmaximum_num(-0x0p+0, NaN)
l: NaN (0x7fc00000)
r: -0.0 (0x80000000)
Add more thorough spec tests for these functions and correct the
implementations.
Canonicalization is also moved to a trait method to centralize
documentation about what it does and doesn't do.
As seen at [1], LLVM uses `long long` on LLP64 (to get a 64-bit integer
matching pointer size) and `long` on everything else, with exceptions
for AArch64 and AVR. Our current logic always uses an `i32`. This
happens to work because LLVM uses 32-bit instructions to check the
output on x86-64, but the GCC checks the full 64-bit register so garbage
in the upper half leads to incorrect results.
Update our return type to be `isize`, with exceptions for AArch64 and
AVR.
Fixes: https://github.com/rust-lang/compiler-builtins/issues/919
[1]: 0cf3c437c1/compiler-rt/lib/builtins/fp_compare_impl.inc (L11-L27)
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.
