Implement API support for v128-globals (#3147)

Found via fuzzing, and looks like these were accidentally left out along
the way SIMD was taking shape.

crates/wasmtime/src/externals.rs

@@ -309,7 +309,7 @@ impl Global {
                 ValType::FuncRef => {
                     from_checked_anyfunc(definition.as_anyfunc() as *mut _, &mut store.opaque())
                 }
-                ty => unimplemented!("Global::get for {:?}", ty),
+                ValType::V128 => Val::V128(*definition.as_u128()),
             }
         }
     }
@@ -355,7 +355,7 @@ impl Global {
                     let old = mem::replace(definition.as_externref_mut(), x.map(|x| x.inner));
                     drop(old);
                 }
-                _ => unimplemented!("Global::set for {:?}", val.ty()),
+                Val::V128(i) => *definition.as_u128_mut() = i,
             }
         }
         Ok(())

crates/wasmtime/src/trampoline/global.rs

@@ -27,6 +27,7 @@ pub fn create_global(store: &mut StoreOpaque<'_>, gt: &GlobalType, val: Val) ->
             Val::I64(i) => wasm::GlobalInit::I64Const(i),
             Val::F32(f) => wasm::GlobalInit::F32Const(f),
             Val::F64(f) => wasm::GlobalInit::F64Const(f),
+            Val::V128(i) => wasm::GlobalInit::V128Const(i.into()),
             Val::ExternRef(None) | Val::FuncRef(None) => wasm::GlobalInit::RefNullConst,
             Val::ExternRef(Some(x)) => {
                 // There is no `GlobalInit` variant for using an existing
@@ -61,7 +62,6 @@ pub fn create_global(store: &mut StoreOpaque<'_>, gt: &GlobalType, val: Val) ->
 
                 wasm::GlobalInit::RefFunc(func_index)
             }
-            _ => unimplemented!("create_global for {:?}", gt),
         },
     };
 

crates/wasmtime/src/values.rs

@@ -270,6 +270,12 @@ impl From<Func> for Val {
     }
 }
 
+impl From<u128> for Val {
+    fn from(val: u128) -> Val {
+        Val::V128(val)
+    }
+}
+
 pub(crate) fn into_checked_anyfunc(
     val: Val,
     store: &mut StoreOpaque,