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Change ComponentType::{size, align} to constants (#4353)

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The more I read over this again the more I think that these should be
constants to explicitly indicate that we're supposed to be able to
optimize for them. Currently I'm predicting that adding memory64 support
will probably double the surface area of each trait (e.g. `lower32` and
`lower64`) rather than have a parameter passed around. This is in the
hopes that having specialized 32 and 64-bit paths will enable better
optimizations within each path instead of having to check all bounds
everywhere.

Additionally one day I'd like to have `fn load(bytes: &[u8;
Self::SIZE32])` but that doesn't work today in Rust.
This commit is contained in:
Alex Crichton
2022-06-29 16:30:54 -05:00
committed by GitHub
parent 7a9479f77c
commit 816e7f7cc7
4 changed files with 139 additions and 195 deletions
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42
crates/component-macro/src/lib.rs
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@@ -192,7 +192,7 @@ impl Expander for LiftExpander {
memory,
&bytes
[#internal::next_field::<#ty>(&mut offset)..]
[..<#ty as wasmtime::component::ComponentType>::size()]
[..<#ty as wasmtime::component::ComponentType>::SIZE32]
)?,));
}
@@ -217,7 +217,7 @@ impl Expander for LiftExpander {
fn load(memory: &#internal::Memory, bytes: &[u8]) -> #internal::anyhow::Result<Self> {
debug_assert!(
(bytes.as_ptr() as usize)
% (<Self as wasmtime::component::ComponentType>::align() as usize)
% (<Self as wasmtime::component::ComponentType>::ALIGN32 as usize)
== 0
);
let mut offset = 0;
@@ -323,7 +323,10 @@ impl Expander for ComponentTypeExpander {
quote!((#literal, <#ty as wasmtime::component::ComponentType>::typecheck),),
);
sizes.extend(quote!(#internal::next_field::<#ty>(&mut size);));
sizes.extend(quote!(
size = #internal::align_to(size, <#ty as wasmtime::component::ComponentType>::ALIGN32);
size += <#ty as wasmtime::component::ComponentType>::SIZE32;
));
unique_types.insert(ty);
}
@@ -331,9 +334,10 @@ impl Expander for ComponentTypeExpander {
let alignments = unique_types
.into_iter()
.map(|ty| {
quote!(align = align.max(
<#ty as wasmtime::component::ComponentType>::align()
);)
let align = quote!(<#ty as wasmtime::component::ComponentType>::ALIGN32);
quote!(if #align > align {
align = #align;
})
})
.collect::<TokenStream>();
@@ -353,6 +357,18 @@ impl Expander for ComponentTypeExpander {
unsafe impl #impl_generics wasmtime::component::ComponentType for #name #ty_generics #where_clause {
type Lower = #lower;
const SIZE32: usize = {
let mut size = 0;
#sizes
size
};
const ALIGN32: u32 = {
let mut align = 1;
#alignments
align
};
#[inline]
fn typecheck(
ty: &#internal::InterfaceType,
@@ -360,20 +376,6 @@ impl Expander for ComponentTypeExpander {
) -> #internal::anyhow::Result<()> {
#internal::typecheck_record(ty, types, &[#field_names_and_checks])
}
#[inline]
fn size() -> usize {
let mut size = 0;
#sizes
size
}
#[inline]
fn align() -> u32 {
let mut align = 1;
#alignments
align
}
}
};