Auto merge of #37373 - nnethercote:html5ever-more-more, r=nrc

Avoid more allocations when compiling html5ever

These three commits reduce the number of allocations performed when compiling html5ever from 13.2M to 10.8M, which speeds up compilation by about 2%.

r? @nrc

2 files changed, 10 insertions, 11 deletions

diff --git a/src/libsyntax/ext/tt/macro_parser.rs b/src/libsyntax/ext/tt/macro_parser.rs
index 74def68b185..91675065eb8 100644
--- a/src/libsyntax/ext/tt/macro_parser.rs
+++ b/src/libsyntax/ext/tt/macro_parser.rs
@@ -92,6 +92,7 @@ use parse::token;
 use print::pprust;
 use ptr::P;
 use tokenstream::{self, TokenTree};
+use util::small_vector::SmallVector;
 
 use std::mem;
 use std::rc::Rc;
@@ -104,7 +105,7 @@ use std::collections::hash_map::Entry::{Vacant, Occupied};
 #[derive(Clone)]
 enum TokenTreeOrTokenTreeVec {
     Tt(tokenstream::TokenTree),
-    TtSeq(Rc<Vec<tokenstream::TokenTree>>),
+    TtSeq(Vec<tokenstream::TokenTree>),
 }
 
 impl TokenTreeOrTokenTreeVec {
@@ -161,7 +162,7 @@ pub fn count_names(ms: &[TokenTree]) -> usize {
     })
 }
 
-pub fn initial_matcher_pos(ms: Rc<Vec<TokenTree>>, sep: Option<Token>, lo: BytePos)
+pub fn initial_matcher_pos(ms: Vec<TokenTree>, sep: Option<Token>, lo: BytePos)
                            -> Box<MatcherPos> {
     let match_idx_hi = count_names(&ms[..]);
     let matches: Vec<_> = (0..match_idx_hi).map(|_| Vec::new()).collect();
@@ -284,12 +285,9 @@ pub fn parse(sess: &ParseSess,
              mut rdr: TtReader,
              ms: &[TokenTree])
              -> NamedParseResult {
-    let mut cur_eis = Vec::new();
-    cur_eis.push(initial_matcher_pos(Rc::new(ms.iter()
-                                                .cloned()
-                                                .collect()),
-                                     None,
-                                     rdr.peek().sp.lo));
+    let mut cur_eis = SmallVector::one(initial_matcher_pos(ms.to_owned(),
+                                                           None,
+                                                           rdr.peek().sp.lo));
 
     loop {
         let mut bb_eis = Vec::new(); // black-box parsed by parser.rs
diff --git a/src/libsyntax/ext/tt/transcribe.rs b/src/libsyntax/ext/tt/transcribe.rs
index 38a926b6e87..8a6a8e53a3e 100644
--- a/src/libsyntax/ext/tt/transcribe.rs
+++ b/src/libsyntax/ext/tt/transcribe.rs
@@ -10,14 +10,15 @@
 use self::LockstepIterSize::*;
 
 use ast::Ident;
-use syntax_pos::{Span, DUMMY_SP};
 use errors::{Handler, DiagnosticBuilder};
 use ext::tt::macro_parser::{NamedMatch, MatchedSeq, MatchedNonterminal};
 use parse::token::{DocComment, MatchNt, SubstNt};
 use parse::token::{Token, Interpolated, NtIdent, NtTT};
 use parse::token;
 use parse::lexer::TokenAndSpan;
+use syntax_pos::{Span, DUMMY_SP};
 use tokenstream::{self, TokenTree};
+use util::small_vector::SmallVector;
 
 use std::rc::Rc;
 use std::ops::Add;
@@ -36,7 +37,7 @@ struct TtFrame {
 pub struct TtReader<'a> {
     pub sp_diag: &'a Handler,
     /// the unzipped tree:
-    stack: Vec<TtFrame>,
+    stack: SmallVector<TtFrame>,
     /* for MBE-style macro transcription */
     interpolations: HashMap<Ident, Rc<NamedMatch>>,
 
@@ -74,7 +75,7 @@ pub fn new_tt_reader_with_doc_flag(sp_diag: &Handler,
                                    -> TtReader {
     let mut r = TtReader {
         sp_diag: sp_diag,
-        stack: vec!(TtFrame {
+        stack: SmallVector::one(TtFrame {
             forest: TokenTree::Sequence(DUMMY_SP, Rc::new(tokenstream::SequenceRepetition {
                 tts: src,
                 // doesn't matter. This merely holds the root unzipping.