Changeset 256423 in webkit

Timestamp:

Feb 11, 2020 8:11:04 PM (4 years ago)

Author:

ysuzuki@apple.com

Message:

Compress ImmutableStyleProperties by using PackedPtr
​https://bugs.webkit.org/show_bug.cgi?id=207604

Reviewed by Mark Lam.

ImmutableStyleProperties is kept so long and consumes enough memory.
We already attempted to compact it by storing CSSProperty's members separately.
But we can compact further by using PackedPtr. This patch makes,

1. Use PackedPtr for CSSValue* in ImmutableStyleProperties so that we can cut some bytes
2. Reorder CSSValue* and StylePropertyMetadata arrays since StylePropertyMetadata requires alignment while PackedPtr<CSSValue> is not.

No behavior change.

• css/StyleProperties.cpp:

(WebCore::sizeForImmutableStylePropertiesWithPropertyCount):
(WebCore::ImmutableStyleProperties::ImmutableStyleProperties):
(WebCore::ImmutableStyleProperties::~ImmutableStyleProperties):
(WebCore::ImmutableStyleProperties::findCustomPropertyIndex const):

• css/StyleProperties.h:

(WebCore::ImmutableStyleProperties::valueArray const):
(WebCore::ImmutableStyleProperties::metadataArray const):
(WebCore::ImmutableStyleProperties::propertyAt const):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• css/StyleProperties.cpp (modified) (4 diffs)
• css/StyleProperties.h (modified) (3 diffs)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2020-02-11  Yusuke Suzuki  <ysuzuki@apple.com>
+
+        Compress ImmutableStyleProperties by using PackedPtr
+        https://bugs.webkit.org/show_bug.cgi?id=207604
+
+        Reviewed by Mark Lam.
+
+        ImmutableStyleProperties is kept so long and consumes enough memory.
+        We already attempted to compact it by storing CSSProperty's members separately.
+        But we can compact further by using PackedPtr. This patch makes,
+
+            1. Use PackedPtr for CSSValue* in ImmutableStyleProperties so that we can cut some bytes
+            2. Reorder CSSValue* and StylePropertyMetadata arrays since StylePropertyMetadata requires alignment while PackedPtr<CSSValue> is not.
+
+        No behavior change.
+
+        * css/StyleProperties.cpp:
+        (WebCore::sizeForImmutableStylePropertiesWithPropertyCount):
+        (WebCore::ImmutableStyleProperties::ImmutableStyleProperties):
+        (WebCore::ImmutableStyleProperties::~ImmutableStyleProperties):
+        (WebCore::ImmutableStyleProperties::findCustomPropertyIndex const):
+        * css/StyleProperties.h:
+        (WebCore::ImmutableStyleProperties::valueArray const):
+        (WebCore::ImmutableStyleProperties::metadataArray const):
+        (WebCore::ImmutableStyleProperties::propertyAt const):
+
 2020-02-11  Carlos Alberto Lopez Perez  <clopez@igalia.com>
 

trunk/Source/WebCore/css/StyleProperties.cpp

@@ -56 +56 @@
 static size_t sizeForImmutableStylePropertiesWithPropertyCount(unsigned count)
 {
-    return sizeof(ImmutableStyleProperties) - sizeof(void*) + sizeof(CSSValue*) * count + sizeof(StylePropertyMetadata) * count;
+    return sizeof(ImmutableStyleProperties) - sizeof(void*) + sizeof(StylePropertyMetadata) * count + sizeof(PackedPtr<const CSSValue>) * count;
 }
 
@@ -95 +95 @@
 {
     StylePropertyMetadata* metadataArray = const_cast<StylePropertyMetadata*>(this->metadataArray());
-    CSSValue** valueArray = const_cast<CSSValue**>(this->valueArray());
+    PackedPtr<CSSValue>* valueArray = bitwise_cast<PackedPtr<CSSValue>*>(this->valueArray());
     for (unsigned i = 0; i < length; ++i) {
         metadataArray[i] = properties[i].metadata();
-        valueArray[i] = properties[i].value();
-        valueArray[i]->ref();
+        auto* value = properties[i].value();
+        valueArray[i] = value;
+        value->ref();
     }
 }
@@ -105 +106 @@
 ImmutableStyleProperties::~ImmutableStyleProperties()
 {
-    CSSValue** valueArray = const_cast<CSSValue**>(this->valueArray());
+    PackedPtr<CSSValue>* valueArray = bitwise_cast<PackedPtr<CSSValue>*>(this->valueArray());
     for (unsigned i = 0; i < m_arraySize; ++i)
         valueArray[i]->deref();
@@ -1472 +1473 @@
         if (metadataArray()[n].m_propertyID == CSSPropertyCustom) {
             // We found a custom property. See if the name matches.
-            if (!valueArray()[n])
+            auto* value = valueArray()[n].get();
+            if (!value)
                 continue;
-            if (downcast<CSSCustomPropertyValue>(*valueArray()[n]).name() == propertyName)
+            if (downcast<CSSCustomPropertyValue>(*value).name() == propertyName)
                 return n;
         }

trunk/Source/WebCore/css/StyleProperties.h

@@ -191 +191 @@
     PropertyReference propertyAt(unsigned index) const;
 
-    const CSSValue** valueArray() const;
-    const StylePropertyMetadata* metadataArray() const;
     int findPropertyIndex(CSSPropertyID) const;
     int findCustomPropertyIndex(const String& propertyName) const;
@@ -199 +197 @@
 
 private:
+    PackedPtr<const CSSValue>* valueArray() const;
+    const StylePropertyMetadata* metadataArray() const;
     ImmutableStyleProperties(const CSSProperty*, unsigned count, CSSParserMode);
 };
 
-inline const CSSValue** ImmutableStyleProperties::valueArray() const
-{
-    return reinterpret_cast<const CSSValue**>(const_cast<const void**>((&(this->m_storage))));
+inline PackedPtr<const CSSValue>* ImmutableStyleProperties::valueArray() const
+{
+    return bitwise_cast<PackedPtr<const CSSValue>*>(bitwise_cast<const uint8_t*>(metadataArray()) + (m_arraySize * sizeof(StylePropertyMetadata)));
 }
 
 inline const StylePropertyMetadata* ImmutableStyleProperties::metadataArray() const
 {
-    return reinterpret_cast_ptr<const StylePropertyMetadata*>(&reinterpret_cast_ptr<const char*>(&(this->m_storage))[m_arraySize * sizeof(CSSValue*)]);
+    return reinterpret_cast<const StylePropertyMetadata*>(const_cast<const void**>((&(this->m_storage))));
 }
 
@@ -290 +290 @@
 inline ImmutableStyleProperties::PropertyReference ImmutableStyleProperties::propertyAt(unsigned index) const
 {
-    return PropertyReference(metadataArray()[index], valueArray()[index]);
+    return PropertyReference(metadataArray()[index], valueArray()[index].get());
 }