From 7a431946c199efadb9b0a0a998fd90c0bbf7c647 Mon Sep 17 00:00:00 2001
From: Patrick Walton <pcwalton@mimiga.net>
Date: Thu, 11 Jun 2015 15:10:49 -0700
Subject: [PATCH] Make the static arrays of style-affecting attributes
 thread-local instead of regenerating and dropping them on the stack over and
 over.

Reduces I-cache footprint and memory barrier traffic on ARM.
---
 src/matching.rs | 74 ++++++++++++++++++++++++++-----------------------
 1 file changed, 39 insertions(+), 35 deletions(-)

diff --git a/src/matching.rs b/src/matching.rs
index c5c5f05..b863884 100644
--- a/src/matching.rs
+++ b/src/matching.rs
@@ -533,37 +533,35 @@ pub enum CommonStyleAffectingAttributeMode {
 
 // NB: This must match the order in `layout::css::matching::CommonStyleAffectingAttributes`.
 #[inline]
-pub fn common_style_affecting_attributes() -> [CommonStyleAffectingAttributeInfo; 5] {
-    [
-        CommonStyleAffectingAttributeInfo {
-            atom: atom!("hidden"),
-            mode: CommonStyleAffectingAttributeMode::IsPresent(HIDDEN_ATTRIBUTE),
-        },
-        CommonStyleAffectingAttributeInfo {
-            atom: atom!("nowrap"),
-            mode: CommonStyleAffectingAttributeMode::IsPresent(NO_WRAP_ATTRIBUTE),
-        },
-        CommonStyleAffectingAttributeInfo {
-            atom: atom!("align"),
-            mode: CommonStyleAffectingAttributeMode::IsEqual("left", ALIGN_LEFT_ATTRIBUTE),
-        },
-        CommonStyleAffectingAttributeInfo {
-            atom: atom!("align"),
-            mode: CommonStyleAffectingAttributeMode::IsEqual("center", ALIGN_CENTER_ATTRIBUTE),
-        },
-        CommonStyleAffectingAttributeInfo {
-            atom: atom!("align"),
-            mode: CommonStyleAffectingAttributeMode::IsEqual("right", ALIGN_RIGHT_ATTRIBUTE),
-        }
-    ]
-}
+thread_local!(pub static COMMON_STYLE_AFFECTING_ATTRIBUTES: [CommonStyleAffectingAttributeInfo; 5] = [
+    CommonStyleAffectingAttributeInfo {
+        atom: atom!("hidden"),
+        mode: CommonStyleAffectingAttributeMode::IsPresent(HIDDEN_ATTRIBUTE),
+    },
+    CommonStyleAffectingAttributeInfo {
+        atom: atom!("nowrap"),
+        mode: CommonStyleAffectingAttributeMode::IsPresent(NO_WRAP_ATTRIBUTE),
+    },
+    CommonStyleAffectingAttributeInfo {
+        atom: atom!("align"),
+        mode: CommonStyleAffectingAttributeMode::IsEqual("left", ALIGN_LEFT_ATTRIBUTE),
+    },
+    CommonStyleAffectingAttributeInfo {
+        atom: atom!("align"),
+        mode: CommonStyleAffectingAttributeMode::IsEqual("center", ALIGN_CENTER_ATTRIBUTE),
+    },
+    CommonStyleAffectingAttributeInfo {
+        atom: atom!("align"),
+        mode: CommonStyleAffectingAttributeMode::IsEqual("right", ALIGN_RIGHT_ATTRIBUTE),
+    }
+]);
 
 /// Attributes that, if present, disable style sharing. All legacy HTML attributes must be in
 /// either this list or `common_style_affecting_attributes`. See the comment in
 /// `synthesize_presentational_hints_for_legacy_attributes`.
-pub fn rare_style_affecting_attributes() -> [Atom; 3] {
-    [ atom!("bgcolor"), atom!("border"), atom!("colspan") ]
-}
+thread_local!(pub static RARE_STYLE_AFFECTING_ATTRIBUTES: [Atom; 3] = [
+    atom!("bgcolor"), atom!("border"), atom!("colspan")
+]);
 
 /// Determines whether the given element matches the given single selector.
 ///
@@ -604,10 +602,12 @@ pub fn matches_simple_selector<'a,N>(selector: &SimpleSelector,
         SimpleSelector::AttrExists(ref attr) => {
             // NB(pcwalton): If you update this, remember to update the corresponding list in
             // `can_share_style_with()` as well.
-            if common_style_affecting_attributes().iter().all(|common_attr_info| {
-                !(common_attr_info.atom == attr.name && match common_attr_info.mode {
-                    CommonStyleAffectingAttributeMode::IsPresent(_) => true,
-                    CommonStyleAffectingAttributeMode::IsEqual(..) => false,
+            if COMMON_STYLE_AFFECTING_ATTRIBUTES.with(|common_style_affecting_attributes| {
+                common_style_affecting_attributes.iter().all(|common_attr_info| {
+                    !(common_attr_info.atom == attr.name && match common_attr_info.mode {
+                        CommonStyleAffectingAttributeMode::IsPresent(_) => true,
+                        CommonStyleAffectingAttributeMode::IsEqual(..) => false,
+                    })
                 })
             }) {
                 *shareable = false;
@@ -616,10 +616,14 @@ pub fn matches_simple_selector<'a,N>(selector: &SimpleSelector,
         }
         SimpleSelector::AttrEqual(ref attr, ref value, case_sensitivity) => {
             if *value != "DIR" &&
-                    common_style_affecting_attributes().iter().all(|common_attr_info| {
-                        !(common_attr_info.atom == attr.name && match common_attr_info.mode {
-                            CommonStyleAffectingAttributeMode::IsEqual(target_value, _) => *value == target_value,
-                            CommonStyleAffectingAttributeMode::IsPresent(_) => false,
+                    COMMON_STYLE_AFFECTING_ATTRIBUTES.with(|common_style_affecting_attributes| {
+                        common_style_affecting_attributes.iter().all(|common_attr_info| {
+                            !(common_attr_info.atom == attr.name && match common_attr_info.mode {
+                                CommonStyleAffectingAttributeMode::IsEqual(target_value, _) => {
+                                    *value == target_value
+                                }
+                                CommonStyleAffectingAttributeMode::IsPresent(_) => false,
+                            })
                         })
                     }) {
                 // FIXME(pcwalton): Remove once we start actually supporting RTL text. This is in