Implement a implicit target feature mechanism

1 files changed, 11 insertions, 0 deletions

diff --git a/compiler/rustc_target/src/target_features.rs b/compiler/rustc_target/src/target_features.rs
index 843e28b17b0..4e2617c4679 100644
--- a/compiler/rustc_target/src/target_features.rs
+++ b/compiler/rustc_target/src/target_features.rs
@@ -339,6 +339,8 @@ const WASM_ALLOWED_FEATURES: &[(&str, Stability)] = &[
     // tidy-alphabetical-end
 ];
 
+const WASM_IMPLICIT_FEATURES: &[(&str, &str)] = &[("relaxed-simd", "simd128")];
+
 const BPF_ALLOWED_FEATURES: &[(&str, Stability)] = &[("alu32", Unstable(sym::bpf_target_feature))];
 
 const CSKY_ALLOWED_FEATURES: &[(&str, Stability)] = &[
@@ -455,4 +457,13 @@ impl super::spec::Target {
             _ => &[],
         }
     }
+
+    /// Returns a list of target features. Each items first target feature
+    /// implicitly enables the second one.
+    pub fn implicit_target_features(&self) -> &'static [(&'static str, &'static str)] {
+        match &*self.arch {
+            "wasm32" | "wasm64" => WASM_IMPLICIT_FEATURES,
+            _ => &[],
+        }
+    }
 }