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Support for `f16` and `f128` is varied across targets, backends, and
backend versions. Eventually we would like to reach a point where all
backends support these approximately equally, but until then we have to
work around some of these nuances of support being observable.
Introduce the `cfg_target_has_reliable_f16_f128` internal feature, which
provides the following new configuration gates:
* `cfg(target_has_reliable_f16)`
* `cfg(target_has_reliable_f16_math)`
* `cfg(target_has_reliable_f128)`
* `cfg(target_has_reliable_f128_math)`
`reliable_f16` and `reliable_f128` indicate that basic arithmetic for
the type works correctly. The `_math` versions indicate that anything
relying on `libm` works correctly, since sometimes this hits a separate
class of codegen bugs.
These options match configuration set by the build script at [1]. The
logic for LLVM support is duplicated as-is from the same script. There
are a few possible updates that will come as a follow up.
The config introduced here is not planned to ever become stable, it is
only intended to replace the build scripts for `std` tests and
`compiler-builtins` that don't have any way to configure based on the
codegen backend.
MCP: https://github.com/rust-lang/compiler-team/issues/866
Closes: https://github.com/rust-lang/compiler-team/issues/866
[1]: 555e1d0386/library/std/build.rs (L84-L186)
32 lines
1016 B
Rust
32 lines
1016 B
Rust
//@ run-pass
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//@ compile-flags: --check-cfg=cfg(target_has_reliable_f16,target_has_reliable_f16_math,target_has_reliable_f128,target_has_reliable_f128_math)
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// Verify that the feature gates and config work and are registered as known config
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// options.
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#![deny(unexpected_cfgs)]
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#![feature(cfg_target_has_reliable_f16_f128)]
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#[cfg(target_has_reliable_f16)]
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pub fn has_f16() {}
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#[cfg(target_has_reliable_f16_math)]
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pub fn has_f16_math() {}
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#[cfg(target_has_reliable_f128 )]
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pub fn has_f128() {}
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#[cfg(target_has_reliable_f128_math)]
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pub fn has_f128_math() {}
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fn main() {
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if cfg!(target_arch = "aarch64") && cfg!(target_os = "linux") {
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// Aarch64+Linux is one target that has support for all features, so use it to spot
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// check that the compiler does indeed enable these gates.
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assert!(cfg!(target_has_reliable_f16));
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assert!(cfg!(target_has_reliable_f16_math));
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assert!(cfg!(target_has_reliable_f128));
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assert!(cfg!(target_has_reliable_f128_math));
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}
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}
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