Add reinterpret-like Wasm APIs (#1555)

* add reinterpret-like Wasm APIs

* use macro to generate reinterpret functions

* move reinterpret funcs definitions up

* use new reinterpret API in translator

* remove TypedVal::reinterpret as it is no longer needed

Author: Robbepop

crates/core/src/typed.rs

@@ -66,16 +66,6 @@ impl TypedVal {
     pub fn untyped(&self) -> UntypedVal {
         self.value
     }
-
-    /// Changes the [`ValType`] of `self` to `ty`.
-    ///
-    /// # Note
-    ///
-    /// This acts similar to a Wasm reinterpret cast and
-    /// the underlying `value` bits are unchanged.
-    pub fn reinterpret(self, ty: ValType) -> Self {
-        Self { ty, ..self }
-    }
 }
 
 impl<T> From<T> for TypedVal

crates/core/src/wasm.rs

@@ -222,6 +222,7 @@ impl_untyped_val! {
 
     fn i32_wrap_i64(value: i64) -> i32 = |v| v as i32;
     fn i64_extend_i32_s(value: i32) -> i64 = i64::from;
+    fn i64_extend_i32_u(value: u32) -> u64 = u64::from;
     fn f32_demote_f64(value: f64) -> f32 = |v| v as f32;
     fn f64_promote_f32(value: f32) -> f64 = f64::from;
 
@@ -283,6 +284,23 @@ impl_untyped_val! {
     fn i64_trunc_sat_f64_u(value: f64) -> u64 = TruncateSaturateInto::truncate_saturate_into;
 }
 
+macro_rules! impl_reinterpret_cast {
+    ( $(fn $name:ident($from:ty) -> $to:ty);* $(;)? ) => {
+        $(
+            #[doc = concat!("Execute the `", stringify!($name), "` Wasm instruction.")]
+            pub fn $name(value: $from) -> $to {
+                <$to>::from_ne_bytes(<$from>::to_ne_bytes(value))
+            }
+        )*
+    };
+}
+impl_reinterpret_cast! {
+    fn i32_reinterpret_f32(f32) -> i32;
+    fn i64_reinterpret_f64(f64) -> i64;
+    fn f32_reinterpret_i32(i32) -> f32;
+    fn f64_reinterpret_i64(i64) -> f64;
+}
+
 macro_rules! gen_load_extend_fn {
     (
         $( (fn $load_fn:ident, fn $load_at_fn:ident, $wrapped:ty => $ty:ty); )*

crates/wasmi/src/engine/translator/func/mod.rs

@@ -1976,25 +1976,11 @@ impl FuncTranslator {
     }
 
     /// Translates a Wasm `reinterpret` instruction.
-    fn translate_reinterpret(&mut self, ty: ValType) -> Result<(), Error> {
-        bail_unreachable!(self);
-        if let TypedProvider::Register(_) = self.stack.peek() {
-            // Nothing to do.
-            //
-            // We try to not manipulate the emulation stack if not needed.
-            return Ok(());
-        }
-        // Case: At this point we know that the top-most stack item is a constant value.
-        //       We pop it, change its type and push it back onto the stack.
-        let TypedProvider::Const(value) = self.stack.pop() else {
-            panic!("the top-most stack item was asserted to be a constant value but a register was found")
-        };
-        self.stack.push_const(value.reinterpret(ty));
-        Ok(())
-    }
-
-    /// Translates a Wasm `i64.extend_i32_u` instruction.
-    fn translate_i64_extend_i32_u(&mut self) -> Result<(), Error> {
+    fn translate_reinterpret<T, R>(&mut self, consteval: fn(T) -> R) -> Result<(), Error>
+    where
+        T: From<TypedVal>,
+        R: Into<TypedVal>,
+    {
         bail_unreachable!(self);
         if let TypedProvider::Register(_) = self.stack.peek() {
             // Nothing to do.
@@ -2007,8 +1993,7 @@ impl FuncTranslator {
         let TypedProvider::Const(value) = self.stack.pop() else {
             panic!("the top-most stack item was asserted to be a constant value but a register was found")
         };
-        debug_assert_eq!(value.ty(), ValType::I32);
-        self.stack.push_const(u64::from(u32::from(value)));
+        self.stack.push_const(consteval(value.into()));
         Ok(())
     }
 

crates/wasmi/src/engine/translator/func/visit.rs

@@ -2844,7 +2844,7 @@ impl<'a> VisitOperator<'a> for FuncTranslator {
     }
 
     fn visit_i64_extend_i32_u(&mut self) -> Self::Output {
-        self.translate_i64_extend_i32_u()
+        self.translate_reinterpret(wasm::i64_extend_i32_u)
     }
 
     fn visit_i64_trunc_f32_s(&mut self) -> Self::Output {
@@ -2916,19 +2916,19 @@ impl<'a> VisitOperator<'a> for FuncTranslator {
     }
 
     fn visit_i32_reinterpret_f32(&mut self) -> Self::Output {
-        self.translate_reinterpret(ValType::I32)
+        self.translate_reinterpret(wasm::i32_reinterpret_f32)
     }
 
     fn visit_i64_reinterpret_f64(&mut self) -> Self::Output {
-        self.translate_reinterpret(ValType::I64)
+        self.translate_reinterpret(wasm::i64_reinterpret_f64)
     }
 
     fn visit_f32_reinterpret_i32(&mut self) -> Self::Output {
-        self.translate_reinterpret(ValType::F32)
+        self.translate_reinterpret(wasm::f32_reinterpret_i32)
     }
 
     fn visit_f64_reinterpret_i64(&mut self) -> Self::Output {
-        self.translate_reinterpret(ValType::F64)
+        self.translate_reinterpret(wasm::f64_reinterpret_i64)
     }
 
     fn visit_i32_extend8_s(&mut self) -> Self::Output {