Configure f16 and f128 support for WebAssembly

Author: kleisauke

build.rs

@@ -283,6 +283,8 @@ 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` miscompiles <https://github.com/llvm/llvm-project/issues/96438>
+        "wasm32" | "wasm64" => (false, true),
         // Most everything else works as of LLVM 19
         _ => (true, true),
     };

testcrate/build.rs

@@ -54,8 +54,9 @@ fn main() {
         || target.starts_with("i586-")
         || 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-")
+        // think the signature is either `(i32) -> f32` or `(f32) -> f32`. See
+        // <https://github.com/llvm/llvm-project/issues/96438>.
+        || target.starts_with("wasm")
     {
         features.insert(Feature::NoSysF16);
         features.insert(Feature::NoSysF16F128Convert);