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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)
13 lines
659 B
Rust
13 lines
659 B
Rust
//@ 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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fn main() {
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cfg!(target_has_reliable_f16);
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//~^ ERROR `cfg(target_has_reliable_f16)` is experimental and subject to change
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cfg!(target_has_reliable_f16_math);
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//~^ ERROR `cfg(target_has_reliable_f16_math)` is experimental and subject to change
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cfg!(target_has_reliable_f128);
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//~^ ERROR `cfg(target_has_reliable_f128)` is experimental and subject to change
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cfg!(target_has_reliable_f128_math);
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//~^ ERROR `cfg(target_has_reliable_f128_math)` is experimental and subject to change
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}
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