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Shrink Path to 16 bytes

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Thanks to the observation (supported by counting) that the vast majority paths have neither generics no type anchors, and thanks to a new datastructure `ThinVecWithHeader` that is essentially `(T, Box<[U]>)` but with the size of a single pointer, we are able to reach this feat.

This (together with `ThinVecWithHeader`) makes the possibility to shrink `TypeRef`, because most types are paths.
This commit is contained in:
Chayim Refael Friedman 2024-10-20 00:50:18 +03:00
parent bccf0062b7
commit 061e5d7f71
13 changed files with 596 additions and 107 deletions
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12
crates/hir-def/src/body/lower.rs
View file

@ -720,12 +720,8 @@ impl ExprCollector<'_> {
fn collect_expr_path(&mut self, e: ast::PathExpr) -> Option<(Path, HygieneId)> {
e.path().and_then(|path| {
let path = self.parse_path(path)?;
let Path::Normal { type_anchor, mod_path, generic_args } = &path else {
panic!("path parsing produced a non-normal path");
};
// Need to enable `mod_path.len() < 1` for `self`.
let may_be_variable =
type_anchor.is_none() && mod_path.len() <= 1 && generic_args.is_none();
let may_be_variable = matches!(&path, Path::BarePath(mod_path) if mod_path.len() <= 1);
let hygiene = if may_be_variable {
self.hygiene_id_for(e.syntax().text_range().start())
} else {
@ -797,7 +793,7 @@ impl ExprCollector<'_> {
ast::Expr::PathExpr(e) => {
let (path, hygiene) = self
.collect_expr_path(e.clone())
.map(|(path, hygiene)| (Pat::Path(Box::new(path)), hygiene))
.map(|(path, hygiene)| (Pat::Path(path), hygiene))
.unwrap_or((Pat::Missing, HygieneId::ROOT));
let pat_id = self.alloc_pat_from_expr(path, syntax_ptr);
if !hygiene.is_root() {
@ -1059,7 +1055,7 @@ impl ExprCollector<'_> {
syntax_ptr,
);
let none_arm = MatchArm {
pat: self.alloc_pat_desugared(Pat::Path(Box::new(option_none))),
pat: self.alloc_pat_desugared(Pat::Path(option_none)),
guard: None,
expr: self.alloc_expr(Expr::Break { expr: None, label: None }, syntax_ptr),
};
@ -1561,7 +1557,7 @@ impl ExprCollector<'_> {
Pat::Ref { pat, mutability }
}
ast::Pat::PathPat(p) => {
let path = p.path().and_then(|path| self.parse_path(path)).map(Box::new);
let path = p.path().and_then(|path| self.parse_path(path));
path.map(Pat::Path).unwrap_or(Pat::Missing)
}
ast::Pat::OrPat(p) => 'b: {

21
crates/hir-def/src/generics.rs
View file

@ -21,7 +21,7 @@ use crate::{
item_tree::{AttrOwner, FileItemTreeId, GenericModItem, GenericsItemTreeNode, ItemTree},
lower::LowerCtx,
nameres::{DefMap, MacroSubNs},
path::{AssociatedTypeBinding, GenericArg, GenericArgs, Path},
path::{AssociatedTypeBinding, GenericArg, GenericArgs, NormalPath, Path},
type_ref::{ConstRef, LifetimeRef, TypeBound, TypeRef, TypeRefId, TypesMap, TypesSourceMap},
AdtId, ConstParamId, GenericDefId, HasModule, ItemTreeLoc, LifetimeParamId,
LocalLifetimeParamId, LocalTypeOrConstParamId, Lookup, TypeOrConstParamId, TypeParamId,
@ -788,19 +788,16 @@ fn copy_path(
to_source_map: &mut TypesSourceMap,
) -> Path {
match path {
Path::Normal { type_anchor, mod_path, generic_args } => {
let type_anchor = type_anchor
Path::BarePath(mod_path) => Path::BarePath(mod_path.clone()),
Path::Normal(path) => {
let type_anchor = path
.type_anchor()
.map(|type_ref| copy_type_ref(type_ref, from, from_source_map, to, to_source_map));
let mod_path = mod_path.clone();
let generic_args = generic_args.as_ref().map(|generic_args| {
generic_args
.iter()
.map(|generic_args| {
copy_generic_args(generic_args, from, from_source_map, to, to_source_map)
})
.collect()
let mod_path = path.mod_path().clone();
let generic_args = path.generic_args().iter().map(|generic_args| {
copy_generic_args(generic_args, from, from_source_map, to, to_source_map)
});
Path::Normal { type_anchor, mod_path, generic_args }
Path::Normal(NormalPath::new(type_anchor, mod_path, generic_args))
}
Path::LangItem(lang_item, name) => Path::LangItem(*lang_item, name.clone()),
}

2
crates/hir-def/src/hir.rs
View file

@ -583,7 +583,7 @@ pub enum Pat {
suffix: Box<[PatId]>,
},
/// This might refer to a variable if a single segment path (specifically, on destructuring assignment).
Path(Box<Path>),
Path(Path),
Lit(ExprId),
Bind {
id: BindingId,

2
crates/hir-def/src/hir/type_ref.rs
View file

@ -201,7 +201,7 @@ pub enum TypeBound {
}
#[cfg(target_pointer_width = "64")]
const _: [(); 48] = [(); ::std::mem::size_of::<TypeBound>()];
const _: [(); 32] = [(); ::std::mem::size_of::<TypeBound>()];
#[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub enum UseArgRef {

150
crates/hir-def/src/path.rs
View file

@ -14,6 +14,7 @@ use crate::{
use hir_expand::name::Name;
use intern::Interned;
use span::Edition;
use stdx::thin_vec::thin_vec_with_header_struct;
use syntax::ast;
pub use hir_expand::mod_path::{path, ModPath, PathKind};
@ -47,20 +48,33 @@ impl Display for ImportAliasDisplay<'_> {
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub enum Path {
/// A normal path
Normal {
/// Type based path like `<T>::foo`.
/// Note that paths like `<Type as Trait>::foo` are desugared to `Trait::<Self=Type>::foo`.
type_anchor: Option<TypeRefId>,
mod_path: Interned<ModPath>,
/// Invariant: the same len as `self.mod_path.segments` or `None` if all segments are `None`.
generic_args: Option<Box<[Option<GenericArgs>]>>,
},
/// `BarePath` is used when the path has neither generics nor type anchor, since the vast majority of paths
/// are in this category, and splitting `Path` this way allows it to be more thin. When the path has either generics
/// or type anchor, it is `Path::Normal` with the generics filled with `None` even if there are none (practically
/// this is not a problem since many more paths have generics than a type anchor).
BarePath(Interned<ModPath>),
/// `Path::Normal` may have empty generics and type anchor (but generic args will be filled with `None`).
Normal(NormalPath),
/// A link to a lang item. It is used in desugaring of things like `it?`. We can show these
/// links via a normal path since they might be private and not accessible in the usage place.
LangItem(LangItemTarget, Option<Name>),
}
// This type is being used a lot, make sure it doesn't grow unintentionally.
#[cfg(target_arch = "x86_64")]
const _: () = {
assert!(size_of::<Path>() == 16);
assert!(size_of::<Option<Path>>() == 16);
};
thin_vec_with_header_struct! {
pub new(pub(crate)) struct NormalPath, NormalPathHeader {
pub generic_args: [Option<GenericArgs>],
pub type_anchor: Option<TypeRefId>,
pub mod_path: Interned<ModPath>; ref,
}
}
/// Generic arguments to a path segment (e.g. the `i32` in `Option<i32>`). This
/// also includes bindings of associated types, like in `Iterator<Item = Foo>`.
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
@ -112,50 +126,49 @@ impl Path {
}
/// Converts a known mod path to `Path`.
pub fn from_known_path(
path: ModPath,
generic_args: impl Into<Box<[Option<GenericArgs>]>>,
) -> Path {
let generic_args = generic_args.into();
assert_eq!(path.len(), generic_args.len());
Path::Normal {
type_anchor: None,
mod_path: Interned::new(path),
generic_args: Some(generic_args),
}
pub fn from_known_path(path: ModPath, generic_args: Vec<Option<GenericArgs>>) -> Path {
Path::Normal(NormalPath::new(None, Interned::new(path), generic_args))
}
/// Converts a known mod path to `Path`.
pub fn from_known_path_with_no_generic(path: ModPath) -> Path {
Path::Normal { type_anchor: None, mod_path: Interned::new(path), generic_args: None }
Path::BarePath(Interned::new(path))
}
#[inline]
pub fn kind(&self) -> &PathKind {
match self {
Path::Normal { mod_path, .. } => &mod_path.kind,
Path::BarePath(mod_path) => &mod_path.kind,
Path::Normal(path) => &path.mod_path().kind,
Path::LangItem(..) => &PathKind::Abs,
}
}
#[inline]
pub fn type_anchor(&self) -> Option<TypeRefId> {
match self {
Path::Normal { type_anchor, .. } => *type_anchor,
Path::LangItem(..) => None,
Path::Normal(path) => path.type_anchor(),
Path::LangItem(..) | Path::BarePath(_) => None,
}
}
#[inline]
pub fn generic_args(&self) -> Option<&[Option<GenericArgs>]> {
match self {
Path::Normal(path) => Some(path.generic_args()),
Path::LangItem(..) | Path::BarePath(_) => None,
}
}
pub fn segments(&self) -> PathSegments<'_> {
match self {
Path::Normal { mod_path, generic_args, .. } => {
let s = PathSegments {
segments: mod_path.segments(),
generic_args: generic_args.as_deref(),
};
if let Some(generic_args) = s.generic_args {
assert_eq!(s.segments.len(), generic_args.len());
}
s
Path::BarePath(mod_path) => {
PathSegments { segments: mod_path.segments(), generic_args: None }
}
Path::Normal(path) => PathSegments {
segments: path.mod_path().segments(),
generic_args: Some(path.generic_args()),
},
Path::LangItem(_, seg) => PathSegments {
segments: seg.as_ref().map_or(&[], |seg| std::slice::from_ref(seg)),
generic_args: None,
@ -165,34 +178,55 @@ impl Path {
pub fn mod_path(&self) -> Option<&ModPath> {
match self {
Path::Normal { mod_path, .. } => Some(mod_path),
Path::BarePath(mod_path) => Some(mod_path),
Path::Normal(path) => Some(path.mod_path()),
Path::LangItem(..) => None,
}
}
pub fn qualifier(&self) -> Option<Path> {
let Path::Normal { mod_path, generic_args, type_anchor } = self else {
return None;
};
if mod_path.is_ident() {
return None;
match self {
Path::BarePath(mod_path) => {
if mod_path.is_ident() {
return None;
}
Some(Path::BarePath(Interned::new(ModPath::from_segments(
mod_path.kind,
mod_path.segments()[..mod_path.segments().len() - 1].iter().cloned(),
))))
}
Path::Normal(path) => {
let mod_path = path.mod_path();
if mod_path.is_ident() {
return None;
}
let type_anchor = path.type_anchor();
let generic_args = path.generic_args();
let qualifier_mod_path = Interned::new(ModPath::from_segments(
mod_path.kind,
mod_path.segments()[..mod_path.segments().len() - 1].iter().cloned(),
));
let qualifier_generic_args = &generic_args[..generic_args.len() - 1];
Some(Path::Normal(NormalPath::new(
type_anchor,
qualifier_mod_path,
qualifier_generic_args.iter().cloned(),
)))
}
Path::LangItem(..) => None,
}
let res = Path::Normal {
type_anchor: *type_anchor,
mod_path: Interned::new(ModPath::from_segments(
mod_path.kind,
mod_path.segments()[..mod_path.segments().len() - 1].iter().cloned(),
)),
generic_args: generic_args.as_ref().map(|it| it[..it.len() - 1].to_vec().into()),
};
Some(res)
}
pub fn is_self_type(&self) -> bool {
let Path::Normal { mod_path, generic_args, type_anchor } = self else {
return false;
};
type_anchor.is_none() && generic_args.as_deref().is_none() && mod_path.is_Self()
match self {
Path::BarePath(mod_path) => mod_path.is_Self(),
Path::Normal(path) => {
path.type_anchor().is_none()
&& path.mod_path().is_Self()
&& path.generic_args().iter().all(|args| args.is_none())
}
Path::LangItem(..) => false,
}
}
}
@ -268,16 +302,6 @@ impl GenericArgs {
impl From<Name> for Path {
fn from(name: Name) -> Path {
Path::Normal {
type_anchor: None,
mod_path: Interned::new(ModPath::from_segments(PathKind::Plain, iter::once(name))),
generic_args: None,
}
}
}
impl From<Name> for Box<Path> {
fn from(name: Name) -> Box<Path> {
Box::new(Path::from(name))
Path::BarePath(Interned::new(ModPath::from_segments(PathKind::Plain, iter::once(name))))
}
}

22
crates/hir-def/src/path/lower.rs
View file

@ -2,7 +2,7 @@
use std::iter;
use crate::{lower::LowerCtx, type_ref::ConstRef};
use crate::{lower::LowerCtx, path::NormalPath, type_ref::ConstRef};
use hir_expand::{
mod_path::resolve_crate_root,
@ -74,11 +74,9 @@ pub(super) fn lower_path(ctx: &LowerCtx<'_>, mut path: ast::Path) -> Option<Path
}
// <T as Trait<A>>::Foo desugars to Trait<Self=T, A>::Foo
Some(trait_ref) => {
let Path::Normal { mod_path, generic_args: path_generic_args, .. } =
Path::from_src(ctx, trait_ref.path()?)?
else {
return None;
};
let path = Path::from_src(ctx, trait_ref.path()?)?;
let mod_path = path.mod_path()?;
let path_generic_args = path.generic_args();
let num_segments = mod_path.segments().len();
kind = mod_path.kind;
@ -136,7 +134,7 @@ pub(super) fn lower_path(ctx: &LowerCtx<'_>, mut path: ast::Path) -> Option<Path
};
}
segments.reverse();
if !generic_args.is_empty() {
if !generic_args.is_empty() || type_anchor.is_some() {
generic_args.resize(segments.len(), None);
generic_args.reverse();
}
@ -165,11 +163,11 @@ pub(super) fn lower_path(ctx: &LowerCtx<'_>, mut path: ast::Path) -> Option<Path
}
let mod_path = Interned::new(ModPath::from_segments(kind, segments));
return Some(Path::Normal {
type_anchor,
mod_path,
generic_args: if generic_args.is_empty() { None } else { Some(generic_args.into()) },
});
if type_anchor.is_none() && generic_args.is_empty() {
return Some(Path::BarePath(mod_path));
} else {
return Some(Path::Normal(NormalPath::new(type_anchor, mod_path, generic_args)));
}
fn qualifier(path: &ast::Path) -> Option<ast::Path> {
if let Some(q) = path.qualifier() {

6
crates/hir-def/src/resolver.rs
View file

@ -167,7 +167,8 @@ impl Resolver {
path: &Path,
) -> Option<(TypeNs, Option<usize>, Option<ImportOrExternCrate>)> {
let path = match path {
Path::Normal { mod_path, .. } => mod_path,
Path::BarePath(mod_path) => mod_path,
Path::Normal(it) => it.mod_path(),
Path::LangItem(l, seg) => {
let type_ns = match *l {
LangItemTarget::Union(it) => TypeNs::AdtId(it.into()),
@ -265,7 +266,8 @@ impl Resolver {
mut hygiene_id: HygieneId,
) -> Option<ResolveValueResult> {
let path = match path {
Path::Normal { mod_path, .. } => mod_path,
Path::BarePath(mod_path) => mod_path,
Path::Normal(it) => it.mod_path(),
Path::LangItem(l, None) => {
return Some(ResolveValueResult::ValueNs(
match *l {