bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

Auto merge of #34652 - jseyfried:fix_expansion_perf, r=nrc

Browse source 
Fix expansion performance regression

**syntax-[breaking-change] cc #31645**

This fixes #34630 by reverting commit 5bf7970 of PR #33943, which landed in #34424.

By removing the `Rc<_>` wrapping around `Delimited` and `SequenceRepetition` in `TokenTree`, 5bf7970 made cloning `TokenTree`s more expensive. While this had no measurable performance impact on the compiler's crates, it caused an order of magnitude performance regression on some macro-heavy code in the wild. I believe this is due to clones of `TokenTree`s in `macro_parser.rs` and/or `macro_rules.rs`.

r? @nrc
This commit is contained in:
bors 2016-07-06 20:04:11 -07:00 • committed by GitHub
commit de78655bca
8 changed files with 72 additions and 53 deletions
Download patch file Download diff file Expand all files Collapse all files

17
src/libsyntax/parse/parser.rs
View file

@ -2688,12 +2688,13 @@ impl<'a> Parser<'a> {
)?;
let (sep, repeat) = self.parse_sep_and_kleene_op()?;
let name_num = macro_parser::count_names(&seq);
return Ok(TokenTree::Sequence(mk_sp(sp.lo, seq_span.hi), SequenceRepetition {
tts: seq,
separator: sep,
op: repeat,
num_captures: name_num
}));
return Ok(TokenTree::Sequence(mk_sp(sp.lo, seq_span.hi),
Rc::new(SequenceRepetition {
tts: seq,
separator: sep,
op: repeat,
num_captures: name_num
})));
} else if self.token.is_keyword(keywords::Crate) {
self.bump();
return Ok(TokenTree::Token(sp, SpecialVarNt(SpecialMacroVar::CrateMacroVar)));
@ -2848,12 +2849,12 @@ impl<'a> Parser<'a> {
_ => {}
}
Ok(TokenTree::Delimited(span, Delimited {
Ok(TokenTree::Delimited(span, Rc::new(Delimited {
delim: delim,
open_span: open_span,
tts: tts,
close_span: close_span,
}))
})))
},
_ => {
// invariants: the current token is not a left-delimiter,