properly use {Read,Write}As traits in Sp's API

Author: Robbepop

crates/core/src/untyped.rs

@@ -35,6 +35,12 @@ pub trait ReadAs<T> {
     fn read_as(&self) -> T;
 }
 
+impl ReadAs<UntypedVal> for UntypedVal {
+    fn read_as(&self) -> UntypedVal {
+        *self
+    }
+}
+
 macro_rules! impl_read_as_for_int {
     ( $( $int:ty ),* $(,)? ) => {
         $(
@@ -83,6 +89,12 @@ pub trait WriteAs<T> {
     fn write_as(&mut self, value: T);
 }
 
+impl WriteAs<UntypedVal> for UntypedVal {
+    fn write_as(&mut self, value: UntypedVal) {
+        *self = value;
+    }
+}
+
 macro_rules! impl_write_as_for_int {
     ( $( $int:ty as $as:ty ),* $(,)? ) => {
         $(

crates/wasmi/src/engine/executor/handler/state.rs

@@ -1,6 +1,6 @@
 use crate::{
     collections::HeadVec,
-    core::UntypedVal,
+    core::{ReadAs, UntypedVal, WriteAs},
     engine::{
         executor::{handler::utils::extract_mem0, CodeMap},
         StackConfig,
@@ -118,20 +118,20 @@ impl<'a> From<&'a mut [UntypedVal]> for Sp {
 impl Sp {
     pub fn get<T>(self, slot: Slot) -> T
     where
-        T: Copy + From<UntypedVal>,
+        UntypedVal: ReadAs<T>,
     {
         let index = usize::from(u16::from(slot));
-        let value = unsafe { *self.value.add(index) };
-        T::from(value)
+        let value = unsafe { &*self.value.add(index) };
+        <UntypedVal as ReadAs<T>>::read_as(value)
     }
 
     pub fn set<T>(self, slot: Slot, value: T)
     where
-        T: Copy + Into<UntypedVal>,
+        UntypedVal: WriteAs<T>,
     {
         let index = usize::from(u16::from(slot));
         let cell = unsafe { &mut *self.value.add(index) };
-        *cell = value.into();
+        <UntypedVal as WriteAs<T>>::write_as(cell, value);
     }
 
     pub unsafe fn as_slice<'a>(self, len: usize) -> &'a [UntypedVal] {

crates/wasmi/src/engine/executor/handler/utils.rs

@@ -1,6 +1,6 @@
 use super::state::{Ip, Sp, VmState};
 use crate::{
-    core::UntypedVal,
+    core::{ReadAs, UntypedVal, WriteAs},
     engine::{DedupFuncType, EngineFunc},
     instance::InstanceEntity,
     ir::{index, Address, BranchOffset, Offset16, Sign, Slot, SlotSpan},
@@ -53,7 +53,8 @@ impl_get_value!(
 
 impl<T> GetValue<T> for Slot
 where
-    T: Copy + From<UntypedVal>,
+    T: Copy,
+    UntypedVal: ReadAs<T>,
 {
     fn get_value(src: Self, sp: Sp) -> T {
         sp.get::<T>(src)
@@ -73,7 +74,7 @@ pub trait SetValue<T> {
 
 impl<T> SetValue<T> for Slot
 where
-    T: Copy + Into<UntypedVal>,
+    UntypedVal: WriteAs<T>,
 {
     fn set_value(src: Self, value: T, sp: Sp) {
         sp.set::<T>(src, value)

crates/wasmi/src/lib.rs

@@ -124,13 +124,15 @@ mod core {
         Memory as CoreMemory,
         MemoryType as CoreMemoryType,
         MemoryTypeBuilder as CoreMemoryTypeBuilder,
+        ReadAs,
         ResourceLimiterRef,
         Table as CoreTable,
         TableType as CoreTableType,
         Typed,
         TypedVal,
         UntypedError,
         UntypedVal,
+        WriteAs,
     };
 }