From 6ceeb0849e181999fc6ecc2cb9dcfdc65b5effd3 Mon Sep 17 00:00:00 2001 From: Trevor Gross Date: Thu, 24 Apr 2025 22:11:23 +0000 Subject: 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]: https://github.com/rust-lang/rust/blob/555e1d0386f024a8359645c3217f4b3eae9be042/library/std/build.rs#L84-L186 --- compiler/rustc_session/src/config/cfg.rs | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'compiler/rustc_session/src') diff --git a/compiler/rustc_session/src/config/cfg.rs b/compiler/rustc_session/src/config/cfg.rs index 231ca434962..cbfe9e0da6a 100644 --- a/compiler/rustc_session/src/config/cfg.rs +++ b/compiler/rustc_session/src/config/cfg.rs @@ -142,6 +142,10 @@ pub(crate) fn disallow_cfgs(sess: &Session, user_cfgs: &Cfg) { | (sym::target_has_atomic, Some(_)) | (sym::target_has_atomic_equal_alignment, Some(_)) | (sym::target_has_atomic_load_store, Some(_)) + | (sym::target_has_reliable_f16, None | Some(_)) + | (sym::target_has_reliable_f16_math, None | Some(_)) + | (sym::target_has_reliable_f128, None | Some(_)) + | (sym::target_has_reliable_f128_math, None | Some(_)) | (sym::target_thread_local, None) => disallow(cfg, "--target"), (sym::fmt_debug, None | Some(_)) => disallow(cfg, "-Z fmt-debug"), (sym::emscripten_wasm_eh, None | Some(_)) => disallow(cfg, "-Z emscripten_wasm_eh"), -- cgit 1.4.1-3-g733a5