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Auto merge of rust-lang#105485 - nnethercote:fix-lint-perf-regression…
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…s, r=cjgillot

Fix lint perf regressions

rust-lang#104863 caused small but widespread regressions in lint performance. I tried to improve things in rust-lang#105291 and rust-lang#105416 with minimal success, before fully understanding what caused the regression. This PR effectively reverts all of rust-lang#105291 and part of rust-lang#104863 to fix the perf regression.

r? `@cjgillot`
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bors committed Dec 12, 2022
2 parents ee6533d + 4ff5a36 commit b397bc0
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Showing 4 changed files with 182 additions and 72 deletions.
149 changes: 97 additions & 52 deletions compiler/rustc_lint/src/early.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,23 +20,23 @@ use rustc_ast::ptr::P;
use rustc_ast::visit::{self as ast_visit, Visitor};
use rustc_ast::{self as ast, walk_list, HasAttrs};
use rustc_middle::ty::RegisteredTools;
use rustc_session::lint::{BufferedEarlyLint, LintBuffer};
use rustc_session::lint::{BufferedEarlyLint, LintBuffer, LintPass};
use rustc_session::Session;
use rustc_span::symbol::Ident;
use rustc_span::Span;

macro_rules! run_early_passes { ($cx:expr, $f:ident, $($args:expr),*) => ({
for pass in $cx.passes.iter_mut() {
pass.$f(&$cx.context, $($args),*);
}
macro_rules! lint_callback { ($cx:expr, $f:ident, $($args:expr),*) => ({
$cx.pass.$f(&$cx.context, $($args),*);
}) }

pub struct EarlyContextAndPasses<'a> {
/// Implements the AST traversal for early lint passes. `T` provides the the
/// `check_*` methods.
pub struct EarlyContextAndPass<'a, T: EarlyLintPass> {
context: EarlyContext<'a>,
passes: Vec<EarlyLintPassObject>,
pass: T,
}

impl<'a> EarlyContextAndPasses<'a> {
impl<'a, T: EarlyLintPass> EarlyContextAndPass<'a, T> {
// This always-inlined function is for the hot call site.
#[inline(always)]
fn inlined_check_id(&mut self, id: ast::NodeId) {
Expand Down Expand Up @@ -70,27 +70,27 @@ impl<'a> EarlyContextAndPasses<'a> {

self.inlined_check_id(id);
debug!("early context: enter_attrs({:?})", attrs);
run_early_passes!(self, enter_lint_attrs, attrs);
lint_callback!(self, enter_lint_attrs, attrs);
f(self);
debug!("early context: exit_attrs({:?})", attrs);
run_early_passes!(self, exit_lint_attrs, attrs);
lint_callback!(self, exit_lint_attrs, attrs);
self.context.builder.pop(push);
}
}

impl<'a> ast_visit::Visitor<'a> for EarlyContextAndPasses<'a> {
impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T> {
fn visit_param(&mut self, param: &'a ast::Param) {
self.with_lint_attrs(param.id, &param.attrs, |cx| {
run_early_passes!(cx, check_param, param);
lint_callback!(cx, check_param, param);
ast_visit::walk_param(cx, param);
});
}

fn visit_item(&mut self, it: &'a ast::Item) {
self.with_lint_attrs(it.id, &it.attrs, |cx| {
run_early_passes!(cx, check_item, it);
lint_callback!(cx, check_item, it);
ast_visit::walk_item(cx, it);
run_early_passes!(cx, check_item_post, it);
lint_callback!(cx, check_item_post, it);
})
}

Expand All @@ -101,10 +101,10 @@ impl<'a> ast_visit::Visitor<'a> for EarlyContextAndPasses<'a> {
}

fn visit_pat(&mut self, p: &'a ast::Pat) {
run_early_passes!(self, check_pat, p);
lint_callback!(self, check_pat, p);
self.check_id(p.id);
ast_visit::walk_pat(self, p);
run_early_passes!(self, check_pat_post, p);
lint_callback!(self, check_pat_post, p);
}

fn visit_pat_field(&mut self, field: &'a ast::PatField) {
Expand All @@ -120,7 +120,7 @@ impl<'a> ast_visit::Visitor<'a> for EarlyContextAndPasses<'a> {

fn visit_expr(&mut self, e: &'a ast::Expr) {
self.with_lint_attrs(e.id, &e.attrs, |cx| {
run_early_passes!(cx, check_expr, e);
lint_callback!(cx, check_expr, e);
ast_visit::walk_expr(cx, e);
})
}
Expand All @@ -141,7 +141,7 @@ impl<'a> ast_visit::Visitor<'a> for EarlyContextAndPasses<'a> {
// Note that statements get their attributes from
// the AST struct that they wrap (e.g. an item)
self.with_lint_attrs(s.id, s.attrs(), |cx| {
run_early_passes!(cx, check_stmt, s);
lint_callback!(cx, check_stmt, s);
cx.check_id(s.id);
});
// The visitor for the AST struct wrapped
Expand All @@ -152,7 +152,7 @@ impl<'a> ast_visit::Visitor<'a> for EarlyContextAndPasses<'a> {
}

fn visit_fn(&mut self, fk: ast_visit::FnKind<'a>, span: Span, id: ast::NodeId) {
run_early_passes!(self, check_fn, fk, span, id);
lint_callback!(self, check_fn, fk, span, id);
self.check_id(id);
ast_visit::walk_fn(self, fk);

Expand Down Expand Up @@ -180,37 +180,37 @@ impl<'a> ast_visit::Visitor<'a> for EarlyContextAndPasses<'a> {

fn visit_variant(&mut self, v: &'a ast::Variant) {
self.with_lint_attrs(v.id, &v.attrs, |cx| {
run_early_passes!(cx, check_variant, v);
lint_callback!(cx, check_variant, v);
ast_visit::walk_variant(cx, v);
})
}

fn visit_ty(&mut self, t: &'a ast::Ty) {
run_early_passes!(self, check_ty, t);
lint_callback!(self, check_ty, t);
self.check_id(t.id);
ast_visit::walk_ty(self, t);
}

fn visit_ident(&mut self, ident: Ident) {
run_early_passes!(self, check_ident, ident);
lint_callback!(self, check_ident, ident);
}

fn visit_local(&mut self, l: &'a ast::Local) {
self.with_lint_attrs(l.id, &l.attrs, |cx| {
run_early_passes!(cx, check_local, l);
lint_callback!(cx, check_local, l);
ast_visit::walk_local(cx, l);
})
}

fn visit_block(&mut self, b: &'a ast::Block) {
run_early_passes!(self, check_block, b);
lint_callback!(self, check_block, b);
self.check_id(b.id);
ast_visit::walk_block(self, b);
}

fn visit_arm(&mut self, a: &'a ast::Arm) {
self.with_lint_attrs(a.id, &a.attrs, |cx| {
run_early_passes!(cx, check_arm, a);
lint_callback!(cx, check_arm, a);
ast_visit::walk_arm(cx, a);
})
}
Expand All @@ -229,19 +229,19 @@ impl<'a> ast_visit::Visitor<'a> for EarlyContextAndPasses<'a> {
}

fn visit_generic_arg(&mut self, arg: &'a ast::GenericArg) {
run_early_passes!(self, check_generic_arg, arg);
lint_callback!(self, check_generic_arg, arg);
ast_visit::walk_generic_arg(self, arg);
}

fn visit_generic_param(&mut self, param: &'a ast::GenericParam) {
self.with_lint_attrs(param.id, &param.attrs, |cx| {
run_early_passes!(cx, check_generic_param, param);
lint_callback!(cx, check_generic_param, param);
ast_visit::walk_generic_param(cx, param);
});
}

fn visit_generics(&mut self, g: &'a ast::Generics) {
run_early_passes!(self, check_generics, g);
lint_callback!(self, check_generics, g);
ast_visit::walk_generics(self, g);
}

Expand All @@ -250,18 +250,18 @@ impl<'a> ast_visit::Visitor<'a> for EarlyContextAndPasses<'a> {
}

fn visit_poly_trait_ref(&mut self, t: &'a ast::PolyTraitRef) {
run_early_passes!(self, check_poly_trait_ref, t);
lint_callback!(self, check_poly_trait_ref, t);
ast_visit::walk_poly_trait_ref(self, t);
}

fn visit_assoc_item(&mut self, item: &'a ast::AssocItem, ctxt: ast_visit::AssocCtxt) {
self.with_lint_attrs(item.id, &item.attrs, |cx| match ctxt {
ast_visit::AssocCtxt::Trait => {
run_early_passes!(cx, check_trait_item, item);
lint_callback!(cx, check_trait_item, item);
ast_visit::walk_assoc_item(cx, item, ctxt);
}
ast_visit::AssocCtxt::Impl => {
run_early_passes!(cx, check_impl_item, item);
lint_callback!(cx, check_impl_item, item);
ast_visit::walk_assoc_item(cx, item, ctxt);
}
});
Expand All @@ -282,28 +282,57 @@ impl<'a> ast_visit::Visitor<'a> for EarlyContextAndPasses<'a> {
}

fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
run_early_passes!(self, check_attribute, attr);
lint_callback!(self, check_attribute, attr);
}

fn visit_mac_def(&mut self, mac: &'a ast::MacroDef, id: ast::NodeId) {
run_early_passes!(self, check_mac_def, mac);
lint_callback!(self, check_mac_def, mac);
self.check_id(id);
}

fn visit_mac_call(&mut self, mac: &'a ast::MacCall) {
run_early_passes!(self, check_mac, mac);
lint_callback!(self, check_mac, mac);
ast_visit::walk_mac(self, mac);
}
}

// Combines multiple lint passes into a single pass, at runtime. Each
// `check_foo` method in `$methods` within this pass simply calls `check_foo`
// once per `$pass`. Compare with `declare_combined_early_lint_pass`, which is
// similar, but combines lint passes at compile time.
struct RuntimeCombinedEarlyLintPass<'a> {
passes: &'a mut [EarlyLintPassObject],
}

#[allow(rustc::lint_pass_impl_without_macro)]
impl LintPass for RuntimeCombinedEarlyLintPass<'_> {
fn name(&self) -> &'static str {
panic!()
}
}

macro_rules! impl_early_lint_pass {
([], [$($(#[$attr:meta])* fn $f:ident($($param:ident: $arg:ty),*);)*]) => (
impl EarlyLintPass for RuntimeCombinedEarlyLintPass<'_> {
$(fn $f(&mut self, context: &EarlyContext<'_>, $($param: $arg),*) {
for pass in self.passes.iter_mut() {
pass.$f(context, $($param),*);
}
})*
}
)
}

crate::early_lint_methods!(impl_early_lint_pass, []);

/// Early lints work on different nodes - either on the crate root, or on freshly loaded modules.
/// This trait generalizes over those nodes.
pub trait EarlyCheckNode<'a>: Copy {
fn id(self) -> ast::NodeId;
fn attrs<'b>(self) -> &'b [ast::Attribute]
where
'a: 'b;
fn check<'b>(self, cx: &mut EarlyContextAndPasses<'b>)
fn check<'b, T: EarlyLintPass>(self, cx: &mut EarlyContextAndPass<'b, T>)
where
'a: 'b;
}
Expand All @@ -318,13 +347,13 @@ impl<'a> EarlyCheckNode<'a> for &'a ast::Crate {
{
&self.attrs
}
fn check<'b>(self, cx: &mut EarlyContextAndPasses<'b>)
fn check<'b, T: EarlyLintPass>(self, cx: &mut EarlyContextAndPass<'b, T>)
where
'a: 'b,
{
run_early_passes!(cx, check_crate, self);
lint_callback!(cx, check_crate, self);
ast_visit::walk_crate(cx, self);
run_early_passes!(cx, check_crate_post, self);
lint_callback!(cx, check_crate_post, self);
}
}

Expand All @@ -338,7 +367,7 @@ impl<'a> EarlyCheckNode<'a> for (ast::NodeId, &'a [ast::Attribute], &'a [P<ast::
{
self.1
}
fn check<'b>(self, cx: &mut EarlyContextAndPasses<'b>)
fn check<'b, T: EarlyLintPass>(self, cx: &mut EarlyContextAndPass<'b, T>)
where
'a: 'b,
{
Expand All @@ -356,21 +385,37 @@ pub fn check_ast_node<'a>(
builtin_lints: impl EarlyLintPass + 'static,
check_node: impl EarlyCheckNode<'a>,
) {
let context = EarlyContext::new(
sess,
!pre_expansion,
lint_store,
registered_tools,
lint_buffer.unwrap_or_default(),
);

// Note: `passes` is often empty. In that case, it's faster to run
// `builtin_lints` directly rather than bundling it up into the
// `RuntimeCombinedEarlyLintPass`.
let passes =
if pre_expansion { &lint_store.pre_expansion_passes } else { &lint_store.early_passes };
let mut passes: Vec<EarlyLintPassObject> = passes.iter().map(|p| (p)()).collect();
passes.push(Box::new(builtin_lints));

let mut cx = EarlyContextAndPasses {
context: EarlyContext::new(
sess,
!pre_expansion,
lint_store,
registered_tools,
lint_buffer.unwrap_or_default(),
),
passes,
};
if passes.is_empty() {
check_ast_node_inner(sess, check_node, context, builtin_lints);
} else {
let mut passes: Vec<_> = passes.iter().map(|mk_pass| (mk_pass)()).collect();
passes.push(Box::new(builtin_lints));
let pass = RuntimeCombinedEarlyLintPass { passes: &mut passes[..] };
check_ast_node_inner(sess, check_node, context, pass);
}
}

pub fn check_ast_node_inner<'a, T: EarlyLintPass>(
sess: &Session,
check_node: impl EarlyCheckNode<'a>,
context: EarlyContext<'_>,
pass: T,
) {
let mut cx = EarlyContextAndPass { context, pass };

cx.with_lint_attrs(check_node.id(), check_node.attrs(), |cx| check_node.check(cx));

// All of the buffered lints should have been emitted at this point.
Expand Down
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