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Sort fields in one pass, and drop 0-sized fields

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This commit is contained in:
Richard Feldman 2020-06-25 01:49:58 -04:00
parent 487c1e3b75
commit ae58ef914d
2 changed files with 46 additions and 29 deletions
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57
compiler/mono/src/layout.rs
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@ -4,7 +4,6 @@ use roc_collections::all::MutMap;
use roc_module::ident::{Lowercase, TagName};
use roc_module::symbol::Symbol;
use roc_types::subs::{Content, FlatType, Subs, Variable};
use std::collections::BTreeMap;
pub const MAX_ENUM_SIZE: usize = (std::mem::size_of::<u8>() * 8) as usize;
@ -304,13 +303,19 @@ fn layout_from_flat_type<'a>(
Record(fields, ext_var) => {
debug_assert!(ext_var_is_empty_record(subs, ext_var));
let btree = fields
.into_iter()
.collect::<BTreeMap<Lowercase, Variable>>();
// Sort the fields by label
let mut sorted_fields = Vec::with_capacity_in(fields.len(), arena);
let mut layouts = Vec::with_capacity_in(btree.len(), arena);
for tuple in fields {
sorted_fields.push(tuple);
}
for (_, field_var) in btree {
sorted_fields.sort_by(|(label1, _), (label2, _)| label1.cmp(label2));
// Determine the layouts of the fields, maintaining sort order
let mut layouts = Vec::with_capacity_in(sorted_fields.len(), arena);
for (_, field_var) in sorted_fields {
let field_content = subs.get_without_compacting(field_var).content;
match Layout::new(arena, field_content, subs, pointer_size) {
@ -327,7 +332,13 @@ fn layout_from_flat_type<'a>(
}
}
Ok(Layout::Struct(layouts.into_bump_slice()))
if layouts.len() == 1 {
// If the record has only one field that isn't zero-sized,
// unwrap it.
Ok(layouts.pop().unwrap())
} else {
Ok(Layout::Struct(layouts.into_bump_slice()))
}
}
TagUnion(tags, ext_var) => {
debug_assert!(ext_var_is_empty_tag_union(subs, ext_var));
@ -348,26 +359,32 @@ fn layout_from_flat_type<'a>(
}
}
pub fn record_fields_btree<'a>(
pub fn sort_record_fields<'a>(
arena: &'a Bump,
var: Variable,
subs: &Subs,
pointer_size: u32,
) -> BTreeMap<Lowercase, Layout<'a>> {
) -> Vec<'a, (Lowercase, Layout<'a>)> {
let mut fields_map = MutMap::default();
match roc_types::pretty_print::chase_ext_record(subs, var, &mut fields_map) {
Ok(()) | Err((_, Content::FlexVar(_))) => {
// collect into btreemap to sort
fields_map
.into_iter()
.map(|(label, var)| {
(
label,
Layout::from_var(arena, var, subs, pointer_size)
.expect("invalid layout from var"),
)
})
.collect::<BTreeMap<Lowercase, Layout<'a>>>()
// Sort the fields by label
let mut sorted_fields = Vec::with_capacity_in(fields_map.len(), arena);
for (label, var) in fields_map {
let layout = Layout::from_var(arena, var, subs, pointer_size)
.expect("invalid layout from var");
// Drop any zero-sized fields like {}
if layout.stack_size(pointer_size) != 0 {
sorted_fields.push((label, layout));
}
}
sorted_fields.sort_by(|(label1, _), (label2, _)| label1.cmp(label2));
sorted_fields
}
Err(other) => panic!("invalid content in record variable: {:?}", other),
}