Fill out MAY_REQUIRE_REALLOC for more types

This is an relatively impactful optimization to the performance of
futures/streams when transferring data from the host to the guest, so
fill this out for more types get the optimization to fire more. This was
found during some improvement of wasi-libc where some code paths weren't
getting hit, but they should,, and this is required to have that work out.

Author: alexcrichton

crates/component-macro/src/component.rs

@@ -359,6 +359,7 @@ fn expand_record_for_component_type(
     let mut lower_field_declarations = TokenStream::new();
     let mut abi_list = TokenStream::new();
     let mut unique_types = HashSet::new();
+    let mut may_require_realloc = TokenStream::new();
 
     for (index, syn::Field { ident, ty, .. }) in fields.iter().enumerate() {
         let generic = format_ident!("T{}", index);
@@ -371,6 +372,9 @@ fn expand_record_for_component_type(
         abi_list.extend(quote!(
             <#ty as #wt::component::ComponentType>::ABI,
         ));
+        may_require_realloc.extend(quote!(
+            <#ty as #wt::component::ComponentType>::MAY_REQUIRE_REALLOC ||
+        ));
 
         unique_types.insert(ty);
     }
@@ -408,6 +412,7 @@ fn expand_record_for_component_type(
 
             const ABI: #internal::CanonicalAbiInfo =
                 #internal::CanonicalAbiInfo::record_static(&[#abi_list]);
+            const MAY_REQUIRE_REALLOC: bool = #may_require_realloc false;
 
             #[inline]
             fn typecheck(
@@ -961,6 +966,7 @@ impl Expander for ComponentTypeExpander {
         let mut lower_generic_args = TokenStream::new();
         let mut abi_list = TokenStream::new();
         let mut unique_types = HashSet::new();
+        let mut may_require_realloc = TokenStream::new();
 
         for (index, VariantCase { attrs, ident, ty }) in cases.iter().enumerate() {
             let rename = find_rename(attrs)?;
@@ -969,6 +975,9 @@ impl Expander for ComponentTypeExpander {
 
             if let Some(ty) = ty {
                 abi_list.extend(quote!(Some(<#ty as #wt::component::ComponentType>::ABI),));
+                may_require_realloc.extend(quote!(
+                    <#ty as #wt::component::ComponentType>::MAY_REQUIRE_REALLOC ||
+                ));
 
                 case_names_and_checks.extend(
                     quote!((#name, Some(<#ty as #wt::component::ComponentType>::typecheck)),),
@@ -1032,6 +1041,7 @@ impl Expander for ComponentTypeExpander {
 
                 const ABI: #internal::CanonicalAbiInfo =
                     #internal::CanonicalAbiInfo::variant_static(&[#abi_list]);
+                const MAY_REQUIRE_REALLOC: bool = #may_require_realloc false;
             }
 
             unsafe impl #impl_generics #internal::ComponentVariant for #name #ty_generics #where_clause {
@@ -1093,6 +1103,7 @@ impl Expander for ComponentTypeExpander {
 
                 const ABI: #internal::CanonicalAbiInfo =
                     #internal::CanonicalAbiInfo::enum_(#cases_len);
+                const MAY_REQUIRE_REALLOC: bool = false;
             }
 
             unsafe impl #internal::ComponentVariant for #name {

crates/wasmtime/src/runtime/component/func/typed.rs

@@ -959,6 +959,7 @@ macro_rules! forward_type_impls {
             type Lower = <$b as ComponentType>::Lower;
 
             const ABI: CanonicalAbiInfo = <$b as ComponentType>::ABI;
+            const MAY_REQUIRE_REALLOC: bool = <$b as ComponentType>::MAY_REQUIRE_REALLOC;
 
             #[inline]
             fn typecheck(ty: &InterfaceType, types: &InstanceType<'_>) -> Result<()> {
@@ -1193,6 +1194,7 @@ macro_rules! floats {
             type Lower = ValRaw;
 
             const ABI: CanonicalAbiInfo = CanonicalAbiInfo::$abi;
+            const MAY_REQUIRE_REALLOC: bool = false;
 
             fn typecheck(ty: &InterfaceType, _types: &InstanceType<'_>) -> Result<()> {
                 match ty {
@@ -1310,6 +1312,7 @@ unsafe impl ComponentType for bool {
     type Lower = ValRaw;
 
     const ABI: CanonicalAbiInfo = CanonicalAbiInfo::SCALAR1;
+    const MAY_REQUIRE_REALLOC: bool = false;
 
     fn typecheck(ty: &InterfaceType, _types: &InstanceType<'_>) -> Result<()> {
         match ty {
@@ -1376,6 +1379,7 @@ unsafe impl ComponentType for char {
     type Lower = ValRaw;
 
     const ABI: CanonicalAbiInfo = CanonicalAbiInfo::SCALAR4;
+    const MAY_REQUIRE_REALLOC: bool = false;
 
     fn typecheck(ty: &InterfaceType, _types: &InstanceType<'_>) -> Result<()> {
         match ty {
@@ -2534,6 +2538,7 @@ where
     type Lower = TupleLower<<u32 as ComponentType>::Lower, T::Lower>;
 
     const ABI: CanonicalAbiInfo = CanonicalAbiInfo::variant_static(&[None, Some(T::ABI)]);
+    const MAY_REQUIRE_REALLOC: bool = T::MAY_REQUIRE_REALLOC;
 
     fn typecheck(ty: &InterfaceType, types: &InstanceType<'_>) -> Result<()> {
         match ty {
@@ -2675,6 +2680,7 @@ where
     type Lower = ResultLower<T::Lower, E::Lower>;
 
     const ABI: CanonicalAbiInfo = CanonicalAbiInfo::variant_static(&[Some(T::ABI), Some(E::ABI)]);
+    const MAY_REQUIRE_REALLOC: bool = T::MAY_REQUIRE_REALLOC || E::MAY_REQUIRE_REALLOC;
 
     fn typecheck(ty: &InterfaceType, types: &InstanceType<'_>) -> Result<()> {
         match ty {
@@ -3032,6 +3038,7 @@ macro_rules! impl_component_ty_for_tuples {
             const ABI: CanonicalAbiInfo = CanonicalAbiInfo::record_static(&[
                 $($t::ABI),*
             ]);
+            const MAY_REQUIRE_REALLOC: bool = false $(|| $t::MAY_REQUIRE_REALLOC)*;
 
             const IS_RUST_UNIT_TYPE: bool = {
                 let mut _is_unit = true;

crates/wasmtime/src/runtime/component/resources/any.rs

@@ -272,6 +272,7 @@ impl ResourceAny {
 
 unsafe impl ComponentType for ResourceAny {
     const ABI: CanonicalAbiInfo = CanonicalAbiInfo::SCALAR4;
+    const MAY_REQUIRE_REALLOC: bool = false;
 
     type Lower = <u32 as ComponentType>::Lower;
 

crates/wasmtime/src/runtime/component/resources/host.rs

@@ -312,6 +312,7 @@ where
     D: PartialEq + Send + Sync + Copy + 'static,
 {
     const ABI: CanonicalAbiInfo = CanonicalAbiInfo::SCALAR4;
+    const MAY_REQUIRE_REALLOC: bool = false;
 
     type Lower = <u32 as ComponentType>::Lower;
 

crates/wasmtime/src/runtime/component/resources/host_dynamic.rs

@@ -144,6 +144,7 @@ impl ResourceDynamic {
 }
 
 unsafe impl ComponentType for ResourceDynamic {
+    const MAY_REQUIRE_REALLOC: bool = false;
     const ABI: CanonicalAbiInfo = HostResource::<Dynamic, u32>::ABI;
     type Lower = crate::ValRaw;
 

crates/wasmtime/src/runtime/component/resources/host_static.rs

@@ -217,6 +217,7 @@ where
 
 unsafe impl<T: 'static> ComponentType for Resource<T> {
     const ABI: CanonicalAbiInfo = HostResource::<Static<T>, ()>::ABI;
+    const MAY_REQUIRE_REALLOC: bool = false;
     type Lower = crate::ValRaw;
 
     fn typecheck(ty: &InterfaceType, types: &InstanceType<'_>) -> Result<()> {