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rustc_resolve: Make macro_rules scope chain compression lazy

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This commit is contained in:
Vadim Petrochenkov 2020-11-14 00:05:05 +03:00
parent 89bce3e908
commit ac4c1f58b9
3 changed files with 21 additions and 36 deletions
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26
compiler/rustc_resolve/src/macros.rs
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@ -62,8 +62,8 @@ pub enum MacroRulesScope<'a> {
}
/// `macro_rules!` scopes are always kept by reference and inside a cell.
/// The reason is that we update all scopes with value `MacroRulesScope::Invocation(invoc_id)`
/// in-place immediately after `invoc_id` gets expanded.
/// The reason is that we update scopes with value `MacroRulesScope::Invocation(invoc_id)`
/// in-place after `invoc_id` gets expanded.
/// This helps to avoid uncontrollable growth of `macro_rules!` scope chains,
/// which usually grow lineraly with the number of macro invocations
/// in a module (including derives) and hurt performance.
@ -173,22 +173,6 @@ impl<'a> ResolverExpand for Resolver<'a> {
let output_macro_rules_scope = self.build_reduced_graph(fragment, parent_scope);
self.output_macro_rules_scopes.insert(expansion, output_macro_rules_scope);
// Update all `macro_rules` scopes referring to this invocation. This is an optimization
// used to avoid long scope chains, see the comments on `MacroRulesScopeRef`.
if let Some(invocation_scopes) = self.invocation_macro_rules_scopes.remove(&expansion) {
for invocation_scope in &invocation_scopes {
invocation_scope.set(output_macro_rules_scope.get());
}
// All `macro_rules` scopes that previously referred to `expansion`
// are now rerouted to its output scope, if it's also an invocation.
if let MacroRulesScope::Invocation(invoc_id) = output_macro_rules_scope.get() {
self.invocation_macro_rules_scopes
.entry(invoc_id)
.or_default()
.extend(invocation_scopes);
}
}
parent_scope.module.unexpanded_invocations.borrow_mut().remove(&expansion);
}
@ -687,11 +671,7 @@ impl<'a> Resolver<'a> {
{
Ok((macro_rules_binding.binding, Flags::MACRO_RULES))
}
MacroRulesScope::Invocation(invoc_id)
if !this.output_macro_rules_scopes.contains_key(&invoc_id) =>
{
Err(Determinacy::Undetermined)
}
MacroRulesScope::Invocation(_) => Err(Determinacy::Undetermined),
_ => Err(Determinacy::Determined),
},
Scope::CrateRoot => {