Add the feature gate and target-features

Author: sayantn

compiler/rustc_codegen_ssa/src/target_features.rs

@@ -80,6 +80,7 @@ pub fn from_target_feature(
                 Some(sym::loongarch_target_feature) => rust_features.loongarch_target_feature,
                 Some(sym::lahfsahf_target_feature) => rust_features.lahfsahf_target_feature,
                 Some(sym::prfchw_target_feature) => rust_features.prfchw_target_feature,
+                Some(sym::x86_amx_intrinsics) => rust_features.x86_amx_intrinsics,
                 Some(name) => bug!("unknown target feature gate {}", name),
                 None => true,
             };

compiler/rustc_feature/src/unstable.rs

@@ -638,6 +638,8 @@ declare_features! (
     (unstable, used_with_arg, "1.60.0", Some(93798)),
     /// Allows `extern "wasm" fn`
     (unstable, wasm_abi, "1.53.0", Some(83788)),
+    /// Allows use of x86 `AMX` target-feature attributes and intrinsics
+    (unstable, x86_amx_intrinsics, "CURRENT_RUSTC_VERSION", Some(126622))
     /// Allows `do yeet` expressions
     (unstable, yeet_expr, "1.62.0", Some(96373)),
     // !!!!    !!!!    !!!!    !!!!   !!!!    !!!!    !!!!    !!!!    !!!!    !!!!    !!!!

compiler/rustc_span/src/symbol.rs

@@ -2046,6 +2046,7 @@ symbols! {
         write_str,
         write_via_move,
         writeln_macro,
+        x86_amx_intrinsics,
         x87_reg,
         xer,
         xmm_reg,

compiler/rustc_target/src/target_features.rs

@@ -192,6 +192,11 @@ const X86_ALLOWED_FEATURES: &[(&str, Stability)] = &[
     // tidy-alphabetical-start
     ("adx", Stable),
     ("aes", Stable),
+    ("amx-bf16", Unstable(sym::x86_amx_intrinsics)),
+    ("amx-complex", Unstable(sym::x86_amx_intrinsics)),
+    ("amx-fp16", Unstable(sym::x86_amx_intrinsics)),
+    ("amx-int8", Unstable(sym::x86_amx_intrinsics)),
+    ("amx-tile", Unstable(sym::x86_amx_intrinsics)),
     ("avx", Stable),
     ("avx2", Stable),
     ("avx512bf16", Unstable(sym::avx512_target_feature)),