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

Implement the internal feature cfg_target_has_reliable_f16_f128

Browse Source 
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)
This commit is contained in:
Trevor Gross
2025-04-24 22:11:23 +00:00
parent 555e1d0386
commit 6ceeb0849e
20 changed files with 311 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
compiler/rustc_codegen_gcc/src/lib.rs
View File

@@ -102,7 +102,7 @@ use rustc_codegen_ssa::back::write::{
};
use rustc_codegen_ssa::base::codegen_crate;
use rustc_codegen_ssa::traits::{CodegenBackend, ExtraBackendMethods, WriteBackendMethods};
use rustc_codegen_ssa::{CodegenResults, CompiledModule, ModuleCodegen};
use rustc_codegen_ssa::{CodegenResults, CompiledModule, ModuleCodegen, TargetConfig};
use rustc_data_structures::fx::FxIndexMap;
use rustc_data_structures::sync::IntoDynSyncSend;
use rustc_errors::DiagCtxtHandle;
@@ -260,8 +260,8 @@ impl CodegenBackend for GccCodegenBackend {
.join(sess)
}
fn target_features_cfg(&self, sess: &Session) -> (Vec<Symbol>, Vec<Symbol>) {
target_features_cfg(sess, &self.target_info)
fn target_config(&self, sess: &Session) -> TargetConfig {
target_config(sess, &self.target_info)
}
}
@@ -485,10 +485,7 @@ fn to_gcc_opt_level(optlevel: Option<OptLevel>) -> OptimizationLevel {
}
/// Returns the features that should be set in `cfg(target_feature)`.
fn target_features_cfg(
sess: &Session,
target_info: &LockedTargetInfo,
) -> (Vec<Symbol>, Vec<Symbol>) {
fn target_config(sess: &Session, target_info: &LockedTargetInfo) -> TargetConfig {
// TODO(antoyo): use global_gcc_features.
let f = |allow_unstable| {
sess.target
@@ -523,5 +520,14 @@ fn target_features_cfg(
let target_features = f(false);
let unstable_target_features = f(true);
(target_features, unstable_target_features)
TargetConfig {
target_features,
unstable_target_features,
// There are no known bugs with GCC support for f16 or f128
has_reliable_f16: true,
has_reliable_f16_math: true,
has_reliable_f128: true,
has_reliable_f128_math: true,
}
}