style: Avoid some allocations in selector serialization.

The allocations in display_to_css_identifier show up in the profiles of
bug 1675628.

Differential Revision: https://phabricator.services.mozilla.com/D97856

1 files changed, 13 insertions, 11 deletions

diff --git a/components/style/gecko/snapshot_helpers.rs b/components/style/gecko/snapshot_helpers.rs
index bd905870353..ee8d7dfd704 100644
--- a/components/style/gecko/snapshot_helpers.rs
+++ b/components/style/gecko/snapshot_helpers.rs
@@ -6,7 +6,9 @@
 
 use crate::gecko_bindings::bindings;
 use crate::gecko_bindings::structs::{self, nsAtom};
-use crate::string_cache::{Atom, WeakAtom};
+use crate::string_cache::WeakAtom;
+use crate::values::AtomIdent;
+use crate::Atom;
 use crate::CaseSensitivityExt;
 use selectors::attr::CaseSensitivity;
 
@@ -85,8 +87,8 @@ pub fn get_id(attrs: &[structs::AttrArray_InternalAttr]) -> Option<&WeakAtom> {
 #[inline(always)]
 pub(super) fn each_exported_part(
     attrs: &[structs::AttrArray_InternalAttr],
-    name: &Atom,
-    mut callback: impl FnMut(&Atom),
+    name: &AtomIdent,
+    mut callback: impl FnMut(&AtomIdent),
 ) {
     let attr = match find_attr(attrs, &atom!("exportparts")) {
         Some(attr) => attr,
@@ -100,7 +102,7 @@ pub(super) fn each_exported_part(
 
     unsafe {
         for atom in std::slice::from_raw_parts(atoms, length) {
-            Atom::with(*atom, &mut callback)
+            AtomIdent::with(*atom, &mut callback)
         }
     }
 }
@@ -108,21 +110,21 @@ pub(super) fn each_exported_part(
 #[inline(always)]
 pub(super) fn imported_part(
     attrs: &[structs::AttrArray_InternalAttr],
-    name: &Atom,
-) -> Option<Atom> {
+    name: &AtomIdent,
+) -> Option<AtomIdent> {
     let attr = find_attr(attrs, &atom!("exportparts"))?;
     let atom = unsafe { bindings::Gecko_Element_ImportedPart(attr, name.as_ptr()) };
     if atom.is_null() {
         return None;
     }
-    Some(unsafe { Atom::from_raw(atom) })
+    Some(AtomIdent(unsafe { Atom::from_raw(atom) }))
 }
 
 /// Given a class or part name, a case sensitivity, and an array of attributes,
 /// returns whether the attribute has that name.
 #[inline(always)]
 pub fn has_class_or_part(
-    name: &Atom,
+    name: &AtomIdent,
     case_sensitivity: CaseSensitivity,
     attr: &structs::nsAttrValue,
 ) -> bool {
@@ -147,15 +149,15 @@ pub fn has_class_or_part(
 #[inline(always)]
 pub fn each_class_or_part<F>(attr: &structs::nsAttrValue, mut callback: F)
 where
-    F: FnMut(&Atom),
+    F: FnMut(&AtomIdent),
 {
     unsafe {
         match get_class_or_part_from_attr(attr) {
             Class::None => {},
-            Class::One(atom) => Atom::with(atom, callback),
+            Class::One(atom) => AtomIdent::with(atom, callback),
             Class::More(atoms) => {
                 for atom in atoms {
-                    Atom::with(atom.mRawPtr, &mut callback)
+                    AtomIdent::with(atom.mRawPtr, &mut callback)
                 }
             },
         }