diff --git a/compiler/rustc_expand/src/mbe/transcribe.rs b/compiler/rustc_expand/src/mbe/transcribe.rs index c969ca7ef89..434891ebc76 100644 --- a/compiler/rustc_expand/src/mbe/transcribe.rs +++ b/compiler/rustc_expand/src/mbe/transcribe.rs @@ -13,19 +13,28 @@ use rustc_errors::DiagnosticBuilder; use rustc_errors::{pluralize, PResult}; use rustc_span::hygiene::{LocalExpnId, Transparency}; use rustc_span::symbol::{sym, Ident, MacroRulesNormalizedIdent}; -use rustc_span::Span; +use rustc_span::{Span, SyntaxContext}; use smallvec::{smallvec, SmallVec}; use std::mem; // A Marker adds the given mark to the syntax context. -struct Marker(LocalExpnId, Transparency); +struct Marker(LocalExpnId, Transparency, FxHashMap); impl MutVisitor for Marker { const VISIT_TOKENS: bool = true; fn visit_span(&mut self, span: &mut Span) { - *span = span.apply_mark(self.0.to_expn_id(), self.1) + // `apply_mark` is a relatively expensive operation, both due to taking hygiene lock, and + // by itself. All tokens in a macro body typically have the same syntactic context, unless + // it's some advanced case with macro-generated macros. So if we cache the marked version + // of that context once, we'll typically have a 100% cache hit rate after that. + let Marker(expn_id, transparency, ref mut cache) = *self; + let data = span.data(); + let marked_ctxt = *cache + .entry(data.ctxt) + .or_insert_with(|| data.ctxt.apply_mark(expn_id.to_expn_id(), transparency)); + *span = data.with_ctxt(marked_ctxt); } } @@ -123,7 +132,7 @@ pub(super) fn transcribe<'a>( // again, and we are done transcribing. let mut result: Vec = Vec::new(); let mut result_stack = Vec::new(); - let mut marker = Marker(cx.current_expansion.id, transparency); + let mut marker = Marker(cx.current_expansion.id, transparency, Default::default()); loop { // Look at the last frame on the stack. diff --git a/compiler/rustc_span/src/hygiene.rs b/compiler/rustc_span/src/hygiene.rs index 08fb1d1345d..6a15961ee20 100644 --- a/compiler/rustc_span/src/hygiene.rs +++ b/compiler/rustc_span/src/hygiene.rs @@ -658,7 +658,7 @@ impl SyntaxContext { } /// Extend a syntax context with a given expansion and transparency. - pub(crate) fn apply_mark(self, expn_id: ExpnId, transparency: Transparency) -> SyntaxContext { + pub fn apply_mark(self, expn_id: ExpnId, transparency: Transparency) -> SyntaxContext { HygieneData::with(|data| data.apply_mark(self, expn_id, transparency)) }