bjoernager/rust
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Auto merge of #50855 - nnethercote:fewer-macro_parser-allocs, r=petrochenkov

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Speed up the macro parser

These three commits reduce the number of allocations done by the macro parser, in some cases dramatically. For example, for a clean check builds of html5ever, the number of allocations is reduced by 40%.

Here are the rustc-benchmarks that are sped up by at least 1%.
```
html5ever-check
        avg: -6.6%      min: -10.3%     max: -4.1%
html5ever
        avg: -5.2%      min: -9.5%      max: -2.8%
html5ever-opt
        avg: -4.3%      min: -9.3%      max: -1.6%
crates.io-check
        avg: -1.8%      min: -2.9%      max: -0.6%
crates.io-opt
        avg: -1.0%      min: -2.2%      max: -0.1%
crates.io
        avg: -1.1%      min: -2.2%      max: -0.2%
```
This commit is contained in:
bors 2018-05-20 08:55:50 +00:00
commit 4c26e2e3fb
5 changed files with 87 additions and 35 deletions
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17
src/libsyntax/parse/parser.rs
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@ -57,6 +57,7 @@ use tokenstream::{self, Delimited, ThinTokenStream, TokenTree, TokenStream};
use symbol::{Symbol, keywords};
use util::ThinVec;
use std::borrow::Cow;
use std::cmp;
use std::mem;
use std::path::{self, Path, PathBuf};
@ -228,7 +229,7 @@ pub struct Parser<'a> {
prev_token_kind: PrevTokenKind,
pub restrictions: Restrictions,
/// Used to determine the path to externally loaded source files
pub directory: Directory,
pub directory: Directory<'a>,
/// Whether to parse sub-modules in other files.
pub recurse_into_file_modules: bool,
/// Name of the root module this parser originated from. If `None`, then the
@ -535,7 +536,7 @@ enum TokenExpectType {
impl<'a> Parser<'a> {
pub fn new(sess: &'a ParseSess,
tokens: TokenStream,
directory: Option<Directory>,
directory: Option<Directory<'a>>,
recurse_into_file_modules: bool,
desugar_doc_comments: bool)
-> Self {
@ -549,7 +550,7 @@ impl<'a> Parser<'a> {
restrictions: Restrictions::empty(),
recurse_into_file_modules,
directory: Directory {
path: PathBuf::new(),
path: Cow::from(PathBuf::new()),
ownership: DirectoryOwnership::Owned { relative: None }
},
root_module_name: None,
@ -572,9 +573,9 @@ impl<'a> Parser<'a> {
if let Some(directory) = directory {
parser.directory = directory;
} else if !parser.span.source_equal(&DUMMY_SP) {
if let FileName::Real(path) = sess.codemap().span_to_unmapped_path(parser.span) {
parser.directory.path = path;
parser.directory.path.pop();
if let FileName::Real(mut path) = sess.codemap().span_to_unmapped_path(parser.span) {
path.pop();
parser.directory.path = Cow::from(path);
}
}
@ -6008,10 +6009,10 @@ impl<'a> Parser<'a> {
fn push_directory(&mut self, id: Ident, attrs: &[Attribute]) {
if let Some(path) = attr::first_attr_value_str_by_name(attrs, "path") {
self.directory.path.push(&path.as_str());
self.directory.path.to_mut().push(&path.as_str());
self.directory.ownership = DirectoryOwnership::Owned { relative: None };
} else {
self.directory.path.push(&id.name.as_str());
self.directory.path.to_mut().push(&id.name.as_str());
}
}