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Rollup merge of #45973 - arielb1:fast-path, r=estebank

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avoid the pprust infrastructure in macro expansion

This changes macro expansion to format the path of a macro directly
instead of usng the pprust infrastructure. The pprust infrastructure
tries to perform line-breaking in a slow fashion, which is undesired
when formatting the path of a macro.

This should to speed up expansion by a fair amount (I saw 20% on a
profiler on `rustc_mir`, and 50% of the time marked as "expansion" in
the profiler/time-passes is actually spent loading dependencies).

r? @jseyfried
This commit is contained in:
Guillaume Gomez 2017-11-16 10:05:03 +01:00 committed by GitHub
commit 3c1ea047da
1 changed files with 24 additions and 3 deletions
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27
src/libsyntax/ext/expand.rs
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@ -29,6 +29,7 @@
use symbol::Symbol;
use symbol::keywords;
use syntax_pos::{Span, DUMMY_SP};
use syntax_pos::hygiene::ExpnFormat;
use tokenstream::{TokenStream, TokenTree};
use util::small_vector::SmallVector;
use visit::Visitor;
@ -151,6 +152,26 @@ fn expect_from_annotatables<I: IntoIterator<Item = Annotatable>>(self, items: I)
}
}
fn macro_bang_format(path: &ast::Path) -> ExpnFormat {
// We don't want to format a path using pretty-printing,
// `format!("{}", path)`, because that tries to insert
// line-breaks and is slow.
let mut path_str = String::with_capacity(64);
for (i, segment) in path.segments.iter().enumerate() {
if i != 0 {
path_str.push_str("::");
}
if segment.identifier.name != keywords::CrateRoot.name() &&
segment.identifier.name != keywords::DollarCrate.name()
{
path_str.push_str(&segment.identifier.name.as_str())
}
}
MacroBang(Symbol::intern(&path_str))
}
pub struct Invocation {
pub kind: InvocationKind,
expansion_kind: ExpansionKind,
@ -517,7 +538,7 @@ fn expand_bang_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) ->
mark.set_expn_info(ExpnInfo {
call_site: span,
callee: NameAndSpan {
format: MacroBang(Symbol::intern(&format!("{}", path))),
format: macro_bang_format(path),
span: def_site_span,
allow_internal_unstable,
allow_internal_unsafe,
@ -564,7 +585,7 @@ fn expand_bang_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) ->
invoc.expansion_data.mark.set_expn_info(ExpnInfo {
call_site: span,
callee: NameAndSpan {
format: MacroBang(Symbol::intern(&format!("{}", path))),
format: macro_bang_format(path),
span: tt_span,
allow_internal_unstable,
allow_internal_unsafe: false,
@ -600,7 +621,7 @@ fn expand_bang_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) ->
invoc.expansion_data.mark.set_expn_info(ExpnInfo {
call_site: span,
callee: NameAndSpan {
format: MacroBang(Symbol::intern(&format!("{}", path))),
format: macro_bang_format(path),
// FIXME procedural macros do not have proper span info
// yet, when they do, we should use it here.
span: None,