rust-lang/rust
1
0
Fork 0
Code Issues Pull Requests Actions 2 Packages Projects Releases Wiki Activity

Rollup merge of #140323 - tgross35:cfg-unstable-float, r=Urgau

Browse Source 
Implement the internal feature `cfg_target_has_reliable_f16_f128`

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)

---

The second commit makes use of this config to replace `cfg_{f16,f128}{,_math}` in `library/`. I omitted providing a `cfg(bootstrap)` configuration to keep things simpler since the next beta branch is in two weeks.

try-job: aarch64-gnu
try-job: i686-msvc-1
try-job: test-various
try-job: x86_64-gnu
try-job: x86_64-msvc-ext2
This commit is contained in:
Chris Denton
2025-04-28 23:29:17 +00:00
committed by GitHub
parent 3f5406f5be dfa972e454
commit e082bf341f
27 changed files with 959 additions and 289 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
compiler/rustc_interface/src/util.rs
View File

@@ -38,14 +38,25 @@ pub(crate) fn add_configuration(
codegen_backend: &dyn CodegenBackend,
) {
let tf = sym::target_feature;
let tf_cfg = codegen_backend.target_config(sess);
let (target_features, unstable_target_features) = codegen_backend.target_features_cfg(sess);
sess.unstable_target_features.extend(tf_cfg.unstable_target_features.iter().copied());
sess.target_features.extend(tf_cfg.target_features.iter().copied());
sess.unstable_target_features.extend(unstable_target_features.iter().copied());
cfg.extend(tf_cfg.target_features.into_iter().map(|feat| (tf, Some(feat))));
sess.target_features.extend(target_features.iter().copied());
cfg.extend(target_features.into_iter().map(|feat| (tf, Some(feat))));
if tf_cfg.has_reliable_f16 {
cfg.insert((sym::target_has_reliable_f16, None));
}
if tf_cfg.has_reliable_f16_math {
cfg.insert((sym::target_has_reliable_f16_math, None));
}
if tf_cfg.has_reliable_f128 {
cfg.insert((sym::target_has_reliable_f128, None));
}
if tf_cfg.has_reliable_f128_math {
cfg.insert((sym::target_has_reliable_f128_math, None));
}
if sess.crt_static(None) {
cfg.insert((tf, Some(sym::crt_dash_static)));