From 4851cc938023d8eac9b9e36a0f8e6e8abc6d9b0e Mon Sep 17 00:00:00 2001 From: Michael Howell Date: Fri, 20 Oct 2023 18:26:20 -0700 Subject: [PATCH] rustdoc: avoid allocating strings primitive link printing This is aimed at hitting the allocator less in a function that gets called a lot. --- src/librustdoc/html/format.rs | 77 +++++++++++++++++++++++------------ 1 file changed, 51 insertions(+), 26 deletions(-) diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs index aa3f7184b4e..29fd880af50 100644 --- a/src/librustdoc/html/format.rs +++ b/src/librustdoc/html/format.rs @@ -847,7 +847,7 @@ fn resolved_path<'cx>( fn primitive_link( f: &mut fmt::Formatter<'_>, prim: clean::PrimitiveType, - name: &str, + name: fmt::Arguments<'_>, cx: &Context<'_>, ) -> fmt::Result { primitive_link_fragment(f, prim, name, "", cx) @@ -856,7 +856,7 @@ fn primitive_link( fn primitive_link_fragment( f: &mut fmt::Formatter<'_>, prim: clean::PrimitiveType, - name: &str, + name: fmt::Arguments<'_>, fragment: &str, cx: &Context<'_>, ) -> fmt::Result { @@ -907,7 +907,7 @@ fn primitive_link_fragment( None => {} } } - f.write_str(name)?; + std::fmt::Display::fmt(&name, f)?; if needs_termination { write!(f, "")?; } @@ -977,9 +977,11 @@ fn fmt_type<'cx>( } clean::Infer => write!(f, "_"), clean::Primitive(clean::PrimitiveType::Never) => { - primitive_link(f, PrimitiveType::Never, "!", cx) + primitive_link(f, PrimitiveType::Never, format_args!("!"), cx) + } + clean::Primitive(prim) => { + primitive_link(f, prim, format_args!("{}", prim.as_sym().as_str()), cx) } - clean::Primitive(prim) => primitive_link(f, prim, prim.as_sym().as_str(), cx), clean::BareFunction(ref decl) => { if f.alternate() { write!( @@ -998,16 +1000,16 @@ fn fmt_type<'cx>( decl.unsafety.print_with_space(), print_abi_with_space(decl.abi) )?; - primitive_link(f, PrimitiveType::Fn, "fn", cx)?; + primitive_link(f, PrimitiveType::Fn, format_args!("fn"), cx)?; write!(f, "{}", decl.decl.print(cx)) } } clean::Tuple(ref typs) => { match &typs[..] { - &[] => primitive_link(f, PrimitiveType::Unit, "()", cx), + &[] => primitive_link(f, PrimitiveType::Unit, format_args!("()"), cx), [one] => { if let clean::Generic(name) = one { - primitive_link(f, PrimitiveType::Tuple, &format!("({name},)"), cx) + primitive_link(f, PrimitiveType::Tuple, format_args!("({name},)"), cx) } else { write!(f, "(")?; // Carry `f.alternate()` into this display w/o branching manually. @@ -1028,7 +1030,10 @@ fn fmt_type<'cx>( primitive_link( f, PrimitiveType::Tuple, - &format!("({})", generic_names.iter().map(|s| s.as_str()).join(", ")), + format_args!( + "({})", + generic_names.iter().map(|s| s.as_str()).join(", ") + ), cx, ) } else { @@ -1047,7 +1052,7 @@ fn fmt_type<'cx>( } clean::Slice(ref t) => match **t { clean::Generic(name) => { - primitive_link(f, PrimitiveType::Slice, &format!("[{name}]"), cx) + primitive_link(f, PrimitiveType::Slice, format_args!("[{name}]"), cx) } _ => { write!(f, "[")?; @@ -1059,7 +1064,7 @@ fn fmt_type<'cx>( clean::Generic(name) if !f.alternate() => primitive_link( f, PrimitiveType::Array, - &format!("[{name}; {n}]", n = Escape(n)), + format_args!("[{name}; {n}]", n = Escape(n)), cx, ), _ => { @@ -1069,7 +1074,12 @@ fn fmt_type<'cx>( write!(f, "; {n}")?; } else { write!(f, "; ")?; - primitive_link(f, PrimitiveType::Array, &format!("{n}", n = Escape(n)), cx)?; + primitive_link( + f, + PrimitiveType::Array, + format_args!("{n}", n = Escape(n)), + cx, + )?; } write!(f, "]") } @@ -1081,22 +1091,32 @@ fn fmt_type<'cx>( }; if matches!(**t, clean::Generic(_)) || t.is_assoc_ty() { - let text = if f.alternate() { - format!("*{m} {ty:#}", ty = t.print(cx)) + let ty = t.print(cx); + if f.alternate() { + primitive_link( + f, + clean::PrimitiveType::RawPointer, + format_args!("*{m} {ty:#}"), + cx, + ) } else { - format!("*{m} {ty}", ty = t.print(cx)) - }; - primitive_link(f, clean::PrimitiveType::RawPointer, &text, cx) + primitive_link( + f, + clean::PrimitiveType::RawPointer, + format_args!("*{m} {ty}"), + cx, + ) + } } else { - primitive_link(f, clean::PrimitiveType::RawPointer, &format!("*{m} "), cx)?; + primitive_link(f, clean::PrimitiveType::RawPointer, format_args!("*{m} "), cx)?; fmt::Display::fmt(&t.print(cx), f) } } clean::BorrowedRef { lifetime: ref l, mutability, type_: ref ty } => { - let lt = match l { - Some(l) => format!("{} ", l.print()), - _ => String::new(), - }; + let lt = display_fn(|f| match l { + Some(l) => write!(f, "{} ", l.print()), + _ => Ok(()), + }); let m = mutability.print_with_space(); let amp = if f.alternate() { "&" } else { "&" }; @@ -1104,7 +1124,7 @@ fn fmt_type<'cx>( return primitive_link( f, PrimitiveType::Reference, - &format!("{amp}{lt}{m}{name}"), + format_args!("{amp}{lt}{m}{name}"), cx, ); } @@ -1254,7 +1274,7 @@ pub(crate) fn print<'a, 'tcx: 'a>( { // Hardcoded anchor library/core/src/primitive_docs.rs // Link should match `# Trait implementations` - primitive_link_fragment(f, PrimitiveType::Tuple, &format!("({name}₁, {name}₂, …, {name}ₙ)"), "#trait-implementations-1", cx)?; + primitive_link_fragment(f, PrimitiveType::Tuple, format_args!("({name}₁, {name}₂, …, {name}ₙ)"), "#trait-implementations-1", cx)?; } else if let clean::BareFunction(bare_fn) = &self.for_ && let [clean::Argument { type_: clean::Type::Generic(name), .. }] = &bare_fn.decl.inputs.values[..] && (self.kind.is_fake_variadic() || self.kind.is_auto()) @@ -1281,7 +1301,7 @@ pub(crate) fn print<'a, 'tcx: 'a>( } else { "" }; - primitive_link_fragment(f, PrimitiveType::Tuple, &format!("fn ({name}₁, {name}₂, …, {name}ₙ{ellipsis})"), "#trait-implementations-1", cx)?; + primitive_link_fragment(f, PrimitiveType::Tuple, format_args!("fn ({name}₁, {name}₂, …, {name}ₙ{ellipsis})"), "#trait-implementations-1", cx)?; // Write output. if !bare_fn.decl.output.is_unit() { write!(f, " -> ")?; @@ -1665,7 +1685,12 @@ pub(crate) fn print<'a, 'tcx: 'a>( } let name = self.path.last(); if let hir::def::Res::PrimTy(p) = self.path.res { - primitive_link(f, PrimitiveType::from(p), name.as_str(), cx)?; + primitive_link( + f, + PrimitiveType::from(p), + format_args!("{}", name.as_str()), + cx, + )?; } else { f.write_str(name.as_str())?; }