wasmi_core: add support for the Wasm simd proposal

crates/core/Cargo.toml

@@ -21,12 +21,15 @@ downcast-rs = { version = "2.0.1", default-features = false, features = ["sync"]
 default = ["std"]
 # Use `no-default-features` for a `no_std` build.
 std = ["downcast-rs/std"]
-
-# Enable this to use 128-bit untyped values.
+# Enables the Wasm `simd` proposal.
 #
-# This mainly affects the `UntypedVal` type since it acts as Wasmi's register cell type.
-value128 = []
+# This also changes the size of `UntypedVal` from 64-bit to 128-bit
+# which may have significant impact on performance and memory usage.
+simd = []
 
 [package.metadata.cargo-udeps.ignore]
 # cargo-udeps cannot detect that libm is used for no_std targets only.
 normal = ["libm"]
+
+[package.metadata.docs.rs]
+all-features = true

crates/core/src/lib.rs

@@ -21,6 +21,9 @@ mod untyped;
 mod value;
 pub mod wasm;
 
+#[cfg(feature = "simd")]
+pub mod simd;
+
 extern crate alloc;
 #[cfg(feature = "std")]
 extern crate std;

crates/core/src/memory.rs

@@ -50,17 +50,25 @@ macro_rules! impl_extend_into {
     };
 }
 impl_extend_into! {
+    // unsigned -> unsigned
+    impl ExtendInto<u16> for u8;
+    impl ExtendInto<u32> for u16;
+    impl ExtendInto<u64> for u32;
+
+    // signed -> signed
+    impl ExtendInto<i16> for i8;
     impl ExtendInto<i32> for i8;
-    impl ExtendInto<i32> for u8;
-    impl ExtendInto<i32> for i16;
-    impl ExtendInto<i32> for u16;
     impl ExtendInto<i64> for i8;
-    impl ExtendInto<i64> for u8;
+    impl ExtendInto<i32> for i16;
     impl ExtendInto<i64> for i16;
-    impl ExtendInto<i64> for u16;
     impl ExtendInto<i64> for i32;
+
+    // unsigned -> signed
+    impl ExtendInto<i32> for u8;
+    impl ExtendInto<i64> for u8;
+    impl ExtendInto<i32> for u16;
+    impl ExtendInto<i64> for u16;
     impl ExtendInto<i64> for u32;
-    impl ExtendInto<u64> for u32;
 }
 
 /// Allows to efficiently load bytes from `memory` into a buffer.
@@ -140,7 +148,7 @@ macro_rules! impl_little_endian_convert_primitive {
         )*
     };
 }
-impl_little_endian_convert_primitive!(u8, u16, u32, u64, i8, i16, i32, i64, f32, f64);
+impl_little_endian_convert_primitive!(u8, u16, u32, u64, u128, i8, i16, i32, i64, i128, f32, f64);
 
 /// Calculates the effective address of a linear memory access.
 ///