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Split ListLen into ListLenU64 and ListLenUsize

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The usize one gets used internally for things like
pattern matches. This is both more efficient (means
they don't have to do unnecessary casts) and also
less error-prone due to e.g. comparing length to
capacity, which is usize.
This commit is contained in:
Richard Feldman 2024-02-14 20:41:52 -05:00
parent a15cc0589c
commit ada83561e5
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17 changed files with 88 additions and 48 deletions
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50
crates/compiler/gen_wasm/src/low_level.rs
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@ -262,28 +262,14 @@ impl<'a> LowLevelCall<'a> {
StrWithCapacity => self.load_args_and_call_zig(backend, bitcode::STR_WITH_CAPACITY),
// List
ListLen => match backend.storage.get(&self.arguments[0]) {
StoredValue::StackMemory { location, .. } => {
let (local_id, offset) =
location.local_and_offset(backend.storage.stack_frame_pointer);
backend.code_builder.get_local(local_id);
// List is stored as (pointer, length, capacity),
// with each of those fields being 4 bytes on wasm.
// So the length is 4 bytes after the start of the struct.
//
// WRAPPER_LEN represents the index of the length field
// (which is 1 as of the writing of this comment). If the field order
// ever changes, WRAPPER_LEN should be updated and this logic should
// continue to work even though this comment may become inaccurate.
backend
.code_builder
.i32_load(Align::Bytes4, offset + (4 * Builtin::WRAPPER_LEN));
ListLenU64 => {
self.load_list_len_usize(backend);
// Length is stored as 32 bits in memory, but List.len returns U64
backend.code_builder.i64_extend_u_i32();
}
_ => internal_error!("invalid storage for List"),
},
// Length is stored as 32 bits in memory on wasm32,
// but List.len always returns U64
backend.code_builder.i64_extend_u_i32();
}
ListLenUsize => self.load_list_len_usize(backend),
ListGetCapacity => self.load_args_and_call_zig(backend, bitcode::LIST_CAPACITY),
@ -2119,6 +2105,28 @@ impl<'a> LowLevelCall<'a> {
}
}
fn load_list_len_usize(&self, backend: &mut WasmBackend<'_, '_>) {
match backend.storage.get(&self.arguments[0]) {
StoredValue::StackMemory { location, .. } => {
let (local_id, offset) =
location.local_and_offset(backend.storage.stack_frame_pointer);
backend.code_builder.get_local(local_id);
// List is stored as (pointer, length, capacity),
// with each of those fields being 4 bytes on wasm.
// So the length is 4 bytes after the start of the struct.
//
// WRAPPER_LEN represents the index of the length field
// (which is 1 as of the writing of this comment). If the field order
// ever changes, WRAPPER_LEN should be updated and this logic should
// continue to work even though this comment may become inaccurate.
backend
.code_builder
.i32_load(Align::Bytes4, offset + (4 * Builtin::WRAPPER_LEN));
}
_ => internal_error!("invalid storage for List"),
}
}
/// Equality and inequality
/// These can operate on any data type (except functions) so they're more complex than other operators.
fn eq_or_neq(&self, backend: &mut WasmBackend<'a, '_>) {