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Pack Scope data more tightly.

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This commit is contained in:
Stephen Chung 2022-02-28 14:00:55 +08:00
parent 15448bf660
commit 54a61bfe00
2 changed files with 43 additions and 46 deletions
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2
src/tests.rs
View File

@ -27,7 +27,7 @@ fn check_struct_sizes() {
#[cfg(target_pointer_width = "64")]
{
assert_eq!(size_of::<Scope>(), 400);
assert_eq!(size_of::<Scope>(), 536);
assert_eq!(size_of::<FnPtr>(), 80);
assert_eq!(size_of::<LexError>(), 56);
assert_eq!(

87
src/types/scope.rs
View File

@ -1,7 +1,7 @@
//! Module that defines the [`Scope`] type representing a function call-stack scope.
use super::dynamic::{AccessMode, Variant};
use crate::{Dynamic, Identifier, StaticVec};
use crate::{Dynamic, Identifier};
use smallvec::SmallVec;
#[cfg(feature = "no_std")]
use std::prelude::v1::*;
@ -53,20 +53,20 @@ const SCOPE_ENTRIES_INLINED: usize = 8;
//
// # Implementation Notes
//
// [`Scope`] is implemented as two arrays of exactly the same length. Variables data (name, type,
// etc.) is manually split into two equal-length arrays. That's because variable names take up the
// most space, with [`Identifier`] being three words long, but in the vast majority of cases the
// name is NOT used to look up a variable. Variable lookup is usually via direct indexing,
// by-passing the name altogether.
// [`Scope`] is implemented as three arrays of exactly the same length. That's because variable
// names take up the most space, with [`Identifier`] being three words long, but in the vast
// majority of cases the name is NOT used to look up a variable. Variable lookup is usually via
// direct indexing, by-passing the name altogether.
//
// Since [`Dynamic`] is reasonably small, packing it tightly improves cache locality when variables
// are accessed.
// [`Dynamic`] is reasonably small so packing it tightly improves cache performance.
#[derive(Debug, Clone, Hash, Default)]
pub struct Scope<'a> {
/// Current value of the entry.
values: SmallVec<[Dynamic; SCOPE_ENTRIES_INLINED]>,
/// (Name, aliases) of the entry.
names: SmallVec<[(Identifier, Option<Box<StaticVec<Identifier>>>); SCOPE_ENTRIES_INLINED]>,
/// Name of the entry.
names: SmallVec<[Identifier; SCOPE_ENTRIES_INLINED]>,
/// Aliases of the entry.
aliases: SmallVec<[Vec<Identifier>; SCOPE_ENTRIES_INLINED]>,
/// Phantom to keep the lifetime parameter in order not to break existing code.
phantom: PhantomData<&'a ()>,
}
@ -77,15 +77,12 @@ impl IntoIterator for Scope<'_> {
#[inline]
fn into_iter(self) -> Self::IntoIter {
Box::new(self.values.into_iter().zip(self.names.into_iter()).map(
|(value, (name, alias))| {
(
name.into(),
value,
alias.map(|a| a.to_vec()).unwrap_or_default(),
)
},
))
Box::new(
self.values
.into_iter()
.zip(self.names.into_iter().zip(self.aliases.into_iter()))
.map(|(value, (name, alias))| (name.into(), value, alias)),
)
}
}
@ -108,6 +105,7 @@ impl Scope<'_> {
Self {
values: SmallVec::new_const(),
names: SmallVec::new_const(),
aliases: SmallVec::new_const(),
phantom: PhantomData,
}
}
@ -134,6 +132,7 @@ impl Scope<'_> {
pub fn clear(&mut self) -> &mut Self {
self.names.clear();
self.values.clear();
self.aliases.clear();
self
}
/// Get the number of entries inside the [`Scope`].
@ -258,7 +257,8 @@ impl Scope<'_> {
access: AccessMode,
mut value: Dynamic,
) -> &mut Self {
self.names.push((name.into(), None));
self.names.push(name.into());
self.aliases.push(Vec::new());
value.set_access_mode(access);
self.values.push(value);
self
@ -293,6 +293,7 @@ impl Scope<'_> {
pub fn rewind(&mut self, size: usize) -> &mut Self {
self.names.truncate(size);
self.values.truncate(size);
self.aliases.truncate(size);
self
}
/// Does the [`Scope`] contain the entry?
@ -311,7 +312,7 @@ impl Scope<'_> {
#[inline]
#[must_use]
pub fn contains(&self, name: &str) -> bool {
self.names.iter().any(|(key, ..)| name == key)
self.names.iter().any(|key| name == key)
}
/// Find an entry in the [`Scope`], starting from the last.
#[inline]
@ -323,7 +324,7 @@ impl Scope<'_> {
.iter()
.rev() // Always search a Scope in reverse order
.enumerate()
.find_map(|(i, (key, ..))| {
.find_map(|(i, key)| {
if name == key {
let index = len - 1 - i;
Some((index, self.values[index].access_mode()))
@ -353,7 +354,7 @@ impl Scope<'_> {
.iter()
.rev()
.enumerate()
.find(|(.., (key, ..))| name == key)
.find(|(.., key)| &name == key)
.and_then(|(index, ..)| self.values[len - 1 - index].flatten_clone().try_cast())
}
/// Check if the named entry in the [`Scope`] is constant.
@ -514,15 +515,9 @@ impl Scope<'_> {
#[cfg(not(feature = "no_module"))]
#[inline]
pub(crate) fn add_entry_alias(&mut self, index: usize, alias: Identifier) -> &mut Self {
let (.., aliases) = self.names.get_mut(index).unwrap();
match aliases {
None => {
let mut list = StaticVec::new_const();
list.push(alias);
*aliases = Some(list.into());
}
Some(aliases) if !aliases.iter().any(|a| a == &alias) => aliases.push(alias),
Some(_) => (),
let aliases = self.aliases.get_mut(index).unwrap();
if !aliases.contains(&alias) {
aliases.push(alias);
}
self
}
@ -533,20 +528,23 @@ impl Scope<'_> {
pub fn clone_visible(&self) -> Self {
let len = self.len();
self.names.iter().rev().enumerate().fold(
Self::new(),
|mut entries, (index, (name, alias))| {
if !entries.names.iter().any(|(key, ..)| key == name) {
self.names
.iter()
.rev()
.enumerate()
.fold(Self::new(), |mut entries, (index, name)| {
if !entries.names.contains(name) {
let orig_value = &self.values[len - 1 - index];
let alias = &self.aliases[len - 1 - index];
let mut value = orig_value.clone();
value.set_access_mode(orig_value.access_mode());
entries.names.push((name.clone(), alias.clone()));
entries.names.push(name.clone());
entries.values.push(value);
entries.aliases.push(alias.clone());
}
entries
},
)
})
}
/// Get an iterator to entries in the [`Scope`].
#[inline]
@ -554,10 +552,8 @@ impl Scope<'_> {
pub(crate) fn into_iter(self) -> impl Iterator<Item = (Identifier, Dynamic, Vec<Identifier>)> {
self.names
.into_iter()
.zip(self.values.into_iter())
.map(|((name, alias), value)| {
(name, value, alias.map(|a| a.to_vec()).unwrap_or_default())
})
.zip(self.values.into_iter().zip(self.aliases.into_iter()))
.map(|(name, (value, alias))| (name, value, alias))
}
/// Get an iterator to entries in the [`Scope`].
/// Shared values are flatten-cloned.
@ -596,7 +592,7 @@ impl Scope<'_> {
self.names
.iter()
.zip(self.values.iter())
.map(|((name, ..), value)| (name.as_ref(), value.is_read_only(), value))
.map(|(name, value)| (name.as_ref(), value.is_read_only(), value))
}
/// Get a reverse iterator to entries in the [`Scope`].
/// Shared values are not expanded.
@ -606,7 +602,7 @@ impl Scope<'_> {
.iter()
.rev()
.zip(self.values.iter().rev())
.map(|((name, ..), value)| (name.as_ref(), value.is_read_only(), value))
.map(|(name, value)| (name.as_ref(), value.is_read_only(), value))
}
/// Remove a range of entries within the [`Scope`].
///
@ -618,6 +614,7 @@ impl Scope<'_> {
pub(crate) fn remove_range(&mut self, start: usize, len: usize) {
self.values.drain(start..start + len).for_each(|_| {});
self.names.drain(start..start + len).for_each(|_| {});
self.aliases.drain(start..start + len).for_each(|_| {});
}
}