Rollup merge of rust-lang#106323 - starkat99:stabilize-f16c_target_fe…

…ature, r=petrochenkov

Stabilize f16c_target_feature

Resolves rust-lang/stdarch#1234

Library PR for stabilizing corresponding intrinsics: rust-lang/stdarch#1366

See also rust-lang#44839 tracking issue for target_feature

compiler/rustc_codegen_ssa/src/target_features.rs

@@ -187,7 +187,7 @@ const X86_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
     ("bmi2", None),
     ("cmpxchg16b", Some(sym::cmpxchg16b_target_feature)),
     ("ermsb", Some(sym::ermsb_target_feature)),
-    ("f16c", Some(sym::f16c_target_feature)),
+    ("f16c", None),
     ("fma", None),
     ("fxsr", None),
     ("gfni", Some(sym::avx512_target_feature)),
@@ -396,7 +396,6 @@ pub fn from_target_feature(
                 Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
                 Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
                 Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
-                Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
                 Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
                 Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
                 Some(sym::aarch64_ver_target_feature) => rust_features.aarch64_ver_target_feature,

compiler/rustc_feature/src/accepted.rs

@@ -161,6 +161,8 @@ declare_features! (
     (accepted, extern_crate_self, "1.34.0", Some(56409), None),
     /// Allows access to crate names passed via `--extern` through prelude.
     (accepted, extern_prelude, "1.30.0", Some(44660), None),
+    /// Allows using F16C intrinsics from `core::arch::{x86, x86_64}`.
+    (accepted, f16c_target_feature, "CURRENT_RUSTC_VERSION", Some(44839), None),
     /// Allows field shorthands (`x` meaning `x: x`) in struct literal expressions.
     (accepted, field_init_shorthand, "1.17.0", Some(37340), None),
     /// Allows `#[must_use]` on functions, and introduces must-use operators (RFC 1940).

compiler/rustc_feature/src/active.rs

@@ -254,7 +254,6 @@ declare_features! (
     (active, bpf_target_feature, "1.54.0", Some(44839), None),
     (active, cmpxchg16b_target_feature, "1.32.0", Some(44839), None),
     (active, ermsb_target_feature, "1.49.0", Some(44839), None),
-    (active, f16c_target_feature, "1.36.0", Some(44839), None),
     (active, hexagon_target_feature, "1.27.0", Some(44839), None),
     (active, mips_target_feature, "1.27.0", Some(44839), None),
     (active, movbe_target_feature, "1.34.0", Some(44839), None),

library/core/src/lib.rs

@@ -239,7 +239,6 @@
 #![feature(arm_target_feature)]
 #![feature(avx512_target_feature)]
 #![feature(cmpxchg16b_target_feature)]
-#![feature(f16c_target_feature)]
 #![feature(hexagon_target_feature)]
 #![feature(mips_target_feature)]
 #![feature(powerpc_target_feature)]
@@ -248,6 +247,7 @@
 #![feature(sse4a_target_feature)]
 #![feature(tbm_target_feature)]
 #![feature(wasm_target_feature)]
+#![cfg_attr(bootstrap, feature(f16c_target_feature))]
 
 // allow using `core::` in intra-doc links
 #[allow(unused_extern_crates)]