Configure f16 and f128 support for wasm32/wasm64

build.rs

@@ -283,6 +283,13 @@ fn configure_f16_f128(target: &Target) {
         "powerpc64" if &target.os == "aix" => (true, false),
         // `f128` crashes <https://github.com/llvm/llvm-project/issues/41838>
         "sparc" | "sparcv9" => (true, false),
+        // `f16` requires half-precision feature, `f128` is unsupported
+        "wasm32" | "wasm64" => (
+            // TODO: This requires updating `WASM_ALLOWED_FEATURES`:
+            // https://github.com/rust-lang/rust/blob/1.80.0/compiler/rustc_target/src/target_features.rs#L310
+            target.features.contains(&"half-precision".to_owned()),
+            false,
+        ),
         // Most everything else works as of LLVM 19
         _ => (true, true),
     };

testcrate/build.rs

@@ -18,6 +18,7 @@ fn main() {
     if target.starts_with("arm-")
         || target.contains("apple-darwin")
         || target.contains("windows-msvc")
+        || target.starts_with("wasm")
         // GCC and LLVM disagree on the ABI of `f16` and `f128` with MinGW. See
         // <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115054>.
         || target.contains("windows-gnu")
@@ -55,7 +56,7 @@ fn main() {
         || target.contains("windows-")
         // Linking says "error: function signature mismatch: __extendhfsf2" and seems to
         // think the signature is either `(i32) -> f32` or `(f32) -> f32`
-        || target.starts_with("wasm32-")
+        || target.starts_with("wasm")
     {
         features.insert(Feature::NoSysF16);
         features.insert(Feature::NoSysF16F128Convert);