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Optimize find_path choice selection

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This commit is contained in:
Lukas Wirth 2024-07-21 10:53:33 +02:00
parent 40bbc684ad
commit a6e4ac705c
1 changed files with 145 additions and 122 deletions
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267
crates/hir-def/src/find_path.rs
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@ -2,12 +2,12 @@
use std::{cell::Cell, cmp::Ordering, iter, ops::BitOr};
use base_db::CrateId;
use base_db::{CrateId, CrateOrigin, LangCrateOrigin};
use hir_expand::{
name::{AsName, Name},
Lookup,
};
use intern::{sym, Symbol};
use intern::sym;
use rustc_hash::FxHashSet;
use crate::{
@ -60,7 +60,7 @@ pub fn find_path(
)
}
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
enum Stability {
Unstable,
Stable,
@ -117,7 +117,7 @@ fn find_path_inner(ctx: &FindPathCtx<'_>, item: ItemInNs, max_len: usize) -> Opt
if let ItemInNs::Types(ModuleDefId::ModuleId(module_id)) = item {
let mut visited_modules = FxHashSet::default();
return find_path_for_module(ctx, &mut visited_modules, module_id, max_len)
.map(|(item, _)| item);
.map(|choice| choice.path);
}
let may_be_in_scope = match ctx.prefix {
@ -135,7 +135,7 @@ fn find_path_inner(ctx: &FindPathCtx<'_>, item: ItemInNs, max_len: usize) -> Opt
// - if the item is in the prelude, return the name from there
if let Some(value) = find_in_prelude(ctx.db, ctx.from_def_map, item, ctx.from) {
return Some(value);
return Some(value.path);
}
if let Some(ModuleDefId::EnumVariantId(variant)) = item.as_module_def_id() {
@ -153,7 +153,7 @@ fn find_path_inner(ctx: &FindPathCtx<'_>, item: ItemInNs, max_len: usize) -> Opt
let mut visited_modules = FxHashSet::default();
calculate_best_path(ctx, &mut visited_modules, item, max_len).map(|(item, _)| item)
calculate_best_path(ctx, &mut visited_modules, item, max_len).map(|choice| choice.path)
}
#[tracing::instrument(skip_all)]
@ -162,11 +162,17 @@ fn find_path_for_module(
visited_modules: &mut FxHashSet<ModuleId>,
module_id: ModuleId,
max_len: usize,
) -> Option<(ModPath, Stability)> {
) -> Option<Choice> {
if let Some(crate_root) = module_id.as_crate_root() {
if crate_root == ctx.from.derive_crate_root() {
// - if the item is the crate root, return `crate`
return Some((ModPath::from_segments(PathKind::Crate, None), Stable));
return Some(Choice {
path: ModPath::from_segments(PathKind::Crate, None),
path_len: 5,
stability: Stable,
prefer_due_to_prelude: false,
sysroot_score: 0,
});
}
// - otherwise if the item is the crate root of a dependency crate, return the name from the extern prelude
@ -193,7 +199,7 @@ fn find_path_for_module(
} else {
PathKind::Plain
};
return Some((ModPath::from_segments(kind, iter::once(name.clone())), Stable));
return Some(Choice::new(ctx.cfg.prefer_prelude, kind, name.clone(), Stable));
}
}
@ -211,25 +217,33 @@ fn find_path_for_module(
);
if let Some(scope_name) = scope_name {
// - if the item is already in scope, return the name under which it is
return Some((
ModPath::from_segments(ctx.prefix.path_kind(), iter::once(scope_name)),
return Some(Choice::new(
ctx.cfg.prefer_prelude,
ctx.prefix.path_kind(),
scope_name,
Stable,
));
}
}
// - if the module can be referenced as self, super or crate, do that
if let Some(mod_path) = is_kw_kind_relative_to_from(ctx.from_def_map, module_id, ctx.from) {
if ctx.prefix != PrefixKind::ByCrate || mod_path.kind == PathKind::Crate {
return Some((mod_path, Stable));
if let Some(kind) = is_kw_kind_relative_to_from(ctx.from_def_map, module_id, ctx.from) {
if ctx.prefix != PrefixKind::ByCrate || kind == PathKind::Crate {
return Some(Choice {
path: ModPath::from_segments(kind, None),
path_len: path_kind_len(kind),
stability: Stable,
prefer_due_to_prelude: false,
sysroot_score: 0,
});
}
}
// - if the module is in the prelude, return it by that path
if let Some(mod_path) =
if let Some(choice) =
find_in_prelude(ctx.db, ctx.from_def_map, ItemInNs::Types(module_id.into()), ctx.from)
{
return Some((mod_path, Stable));
return Some(choice);
}
calculate_best_path(ctx, visited_modules, ItemInNs::Types(module_id.into()), max_len)
}
@ -256,7 +270,7 @@ fn find_in_prelude(
local_def_map: &DefMap,
item: ItemInNs,
from: ModuleId,
) -> Option<ModPath> {
) -> Option<Choice> {
let (prelude_module, _) = local_def_map.prelude()?;
let prelude_def_map = prelude_module.def_map(db);
let prelude_scope = &prelude_def_map[prelude_module.local_id].scope;
@ -278,7 +292,7 @@ fn find_in_prelude(
});
if found_and_same_def.unwrap_or(true) {
Some(ModPath::from_segments(PathKind::Plain, iter::once(name.clone())))
Some(Choice::new(false, PathKind::Plain, name.clone(), Stable))
} else {
None
}
@ -288,7 +302,7 @@ fn is_kw_kind_relative_to_from(
def_map: &DefMap,
item: ModuleId,
from: ModuleId,
) -> Option<ModPath> {
) -> Option<PathKind> {
if item.krate != from.krate || item.is_within_block() || from.is_within_block() {
return None;
}
@ -296,14 +310,11 @@ fn is_kw_kind_relative_to_from(
let from = from.local_id;
if item == from {
// - if the item is the module we're in, use `self`
Some(ModPath::from_segments(PathKind::SELF, None))
Some(PathKind::SELF)
} else if let Some(parent_id) = def_map[from].parent {
if item == parent_id {
// - if the item is the parent module, use `super` (this is not used recursively, since `super::super` is ugly)
Some(ModPath::from_segments(
if parent_id == DefMap::ROOT { PathKind::Crate } else { PathKind::Super(1) },
None,
))
Some(if parent_id == DefMap::ROOT { PathKind::Crate } else { PathKind::Super(1) })
} else {
None
}
@ -318,7 +329,7 @@ fn calculate_best_path(
visited_modules: &mut FxHashSet<ModuleId>,
item: ItemInNs,
max_len: usize,
) -> Option<(ModPath, Stability)> {
) -> Option<Choice> {
if max_len <= 1 {
// recursive base case, we can't find a path prefix of length 0, one segment is occupied by
// the item's name itself.
@ -336,25 +347,7 @@ fn calculate_best_path(
}
ctx.fuel.set(fuel - 1);
let mut best_path = None;
let mut best_path_len = max_len;
let mut process = |mut path: (ModPath, Stability), name, best_path_len: &mut _| {
path.0.push_segment(name);
let new_path = match best_path.take() {
Some(best_path) => select_best_path(best_path, path, ctx.cfg),
None => path,
};
if new_path.1 == Stable {
*best_path_len = new_path.0.len();
}
match &mut best_path {
Some((old_path, old_stability)) => {
*old_path = new_path.0;
*old_stability = zip_stability(*old_stability, new_path.1);
}
None => best_path = Some(new_path),
}
};
let mut best_choice = None::<Choice>;
let db = ctx.db;
if item.krate(db) == Some(ctx.from.krate) {
// Item was defined in the same crate that wants to import it. It cannot be found in any
@ -366,10 +359,16 @@ fn calculate_best_path(
}
// we are looking for paths of length up to best_path_len, any longer will make it be
// less optimal. The -1 is due to us pushing name onto it afterwards.
if let Some(path) =
find_path_for_module(ctx, visited_modules, module_id, best_path_len - 1)
{
process(path, name.clone(), &mut best_path_len);
if let Some(path) = find_path_for_module(
ctx,
visited_modules,
module_id,
best_choice.as_ref().map_or(max_len, |it| it.path_len) - 1,
) {
best_choice = Some(match best_choice.take() {
Some(best_choice) => best_choice.select(path, name.clone()),
None => path.push(ctx.cfg.prefer_prelude, name.clone()),
});
}
})
} else {
@ -377,7 +376,7 @@ fn calculate_best_path(
// too (unless we can't name it at all). It could *also* be (re)exported by the same crate
// that wants to import it here, but we always prefer to use the external path here.
let mut process_dep = |dep: CrateId| {
let mut process_dep = |dep: CrateId, score| {
let import_map = db.import_map(dep);
let Some(import_info_for) = import_map.import_info_for(item) else {
return false;
@ -391,24 +390,33 @@ fn calculate_best_path(
// Determine best path for containing module and append last segment from `info`.
// FIXME: we should guide this to look up the path locally, or from the same crate again?
let path =
find_path_for_module(ctx, visited_modules, info.container, best_path_len - 1);
let Some((path, path_stability)) = path else {
let choice = find_path_for_module(
ctx,
visited_modules,
info.container,
best_choice.as_ref().map_or(max_len, |it| it.path_len) - 1,
);
let Some(mut choice) = choice else {
continue;
};
choice.sysroot_score = score;
cov_mark::hit!(partially_imported);
let path = (
path,
zip_stability(path_stability, if info.is_unstable { Unstable } else { Stable }),
choice.stability = zip_stability(
choice.stability,
if info.is_unstable { Unstable } else { Stable },
);
process(path, info.name.clone(), &mut best_path_len);
best_choice = Some(match best_choice.take() {
Some(best_choice) => best_choice.select(choice, info.name.clone()),
None => choice.push(ctx.cfg.prefer_prelude, info.name.clone()),
});
processed_something = true;
}
processed_something
};
let dependencies = &db.crate_graph()[ctx.from.krate].dependencies;
let crate_graph = db.crate_graph();
let dependencies = &crate_graph[ctx.from.krate].dependencies;
if ctx.is_std_item {
// The item we are searching for comes from the sysroot libraries, so skip prefer looking in
// the sysroot libraries directly.
@ -417,89 +425,104 @@ fn calculate_best_path(
let processed = dependencies
.iter()
.filter(|it| it.is_sysroot())
.map(|dep| process_dep(dep.crate_id))
.map(|dep| {
(
match crate_graph[dep.crate_id].origin {
CrateOrigin::Lang(LangCrateOrigin::Std) if ctx.cfg.prefer_no_std => 4,
CrateOrigin::Lang(LangCrateOrigin::Std) => 1,
CrateOrigin::Lang(LangCrateOrigin::Alloc) => 3,
CrateOrigin::Lang(LangCrateOrigin::ProcMacro) => 3,
CrateOrigin::Lang(LangCrateOrigin::Test) => 3,
CrateOrigin::Lang(LangCrateOrigin::Core) => 2,
CrateOrigin::Lang(LangCrateOrigin::Other) => 1,
_ => 0,
},
dep.crate_id,
)
})
.map(|(score, crate_id)| process_dep(crate_id, score))
.reduce(BitOr::bitor)
.unwrap_or(false);
if processed {
// Found a path in a sysroot crate, so return it.
return best_path;
return best_choice;
}
}
dependencies
.iter()
.filter(|it| !ctx.is_std_item || !it.is_sysroot())
.for_each(|dep| _ = process_dep(dep.crate_id));
.for_each(|dep| _ = process_dep(dep.crate_id, 0));
}
best_path
best_choice
}
/// Select the best (most relevant) path between two paths.
/// This accounts for stability, path length whether, std should be chosen over alloc/core paths as
/// well as ignoring prelude like paths or not.
fn select_best_path(
old_path @ (_, old_stability): (ModPath, Stability),
new_path @ (_, new_stability): (ModPath, Stability),
cfg: ImportPathConfig,
) -> (ModPath, Stability) {
match (old_stability, new_stability) {
(Stable, Unstable) => return old_path,
(Unstable, Stable) => return new_path,
_ => {}
}
let std_crates: [Symbol; 3] = [sym::std.clone(), sym::core.clone(), sym::alloc.clone()];
struct Choice {
path: ModPath,
/// The length in characters of the path
path_len: usize,
/// The stability of the path
stability: Stability,
/// Whether this path contains a prelude segment and preference for it has been signaled
prefer_due_to_prelude: bool,
/// non-zero if this is a path in a sysroot crate, we want to choose the highest ranked std crate
sysroot_score: u8,
}
let choose = |new: (ModPath, _), old: (ModPath, _)| {
let (new_path, _) = &new;
let (old_path, _) = &old;
let new_has_prelude = new_path.segments().iter().any(|seg| *seg == sym::prelude.clone());
let old_has_prelude = old_path.segments().iter().any(|seg| *seg == sym::prelude.clone());
match (new_has_prelude, old_has_prelude, cfg.prefer_prelude) {
(true, false, true) | (false, true, false) => new,
(true, false, false) | (false, true, true) => old,
// no prelude difference in the paths, so pick the shorter one
(true, true, _) | (false, false, _) => {
let new_path_is_shorter = new_path
.len()
.cmp(&old_path.len())
.then_with(|| new_path.textual_len().cmp(&old_path.textual_len()))
.is_lt();
if new_path_is_shorter {
new
} else {
old
impl Choice {
fn new(prefer_prelude: bool, kind: PathKind, name: Name, stability: Stability) -> Self {
Self {
path_len: path_kind_len(kind) + name.as_str().len(),
stability,
prefer_due_to_prelude: prefer_prelude && name == sym::prelude,
sysroot_score: 0,
path: ModPath::from_segments(kind, iter::once(name)),
}
}
fn push(mut self, prefer_prelude: bool, name: Name) -> Self {
self.path_len += name.as_str().len();
self.prefer_due_to_prelude |= prefer_prelude && name == sym::prelude;
self.path.push_segment(name);
self
}
fn select(self, mut other: Choice, name: Name) -> Self {
match other
.stability
.cmp(&self.stability)
.then_with(|| other.prefer_due_to_prelude.cmp(&self.prefer_due_to_prelude))
.then_with(|| self.sysroot_score.cmp(&other.sysroot_score))
.then_with(|| (self.path.len()).cmp(&(other.path.len() + 1)))
{
Ordering::Less => self,
Ordering::Equal => {
other.path_len += name.as_str().len();
match self.path_len.cmp(&other.path_len) {
Ordering::Less | Ordering::Equal => self,
Ordering::Greater => {
other.path.push_segment(name);
other
}
}
}
}
};
match (old_path.0.segments().first(), new_path.0.segments().first()) {
(Some(old), Some(new))
if std_crates.contains(old.symbol()) && std_crates.contains(new.symbol()) =>
{
let rank = match cfg.prefer_no_std {
false => |name: &Name| match name {
name if *name == sym::core.clone() => 0,
name if *name == sym::alloc.clone() => 1,
name if *name == sym::std.clone() => 2,
_ => unreachable!(),
},
true => |name: &Name| match name {
name if *name == sym::core.clone() => 2,
name if *name == sym::alloc.clone() => 1,
name if *name == sym::std.clone() => 0,
_ => unreachable!(),
},
};
let nrank = rank(new);
let orank = rank(old);
match nrank.cmp(&orank) {
Ordering::Less => old_path,
Ordering::Equal => choose(new_path, old_path),
Ordering::Greater => new_path,
Ordering::Greater => {
other.path.push_segment(name);
other
}
}
_ => choose(new_path, old_path),
}
}
fn path_kind_len(kind: PathKind) -> usize {
match kind {
PathKind::Plain => 0,
PathKind::Super(0) => 4,
PathKind::Super(s) => s as usize * 5,
PathKind::Crate => 5,
PathKind::Abs => 2,
PathKind::DollarCrate(_) => 0,
}
}