Title: [292310] trunk/Source/WebCore
- Revision
- 292310
- Author
- cdu...@apple.com
- Date
- 2022-04-04 12:25:09 -0700 (Mon, 04 Apr 2022)
Log Message
Simplify / Optimize the whitespace cache implementation
https://bugs.webkit.org/show_bug.cgi?id=238736
Reviewed by Sam Weinig.
Instead of using 2 C arrays of size maximumCachedStringLength + 1 Vector with an inline
buffer of size maximumCachedStringLength, we now used a single FixedVector of size
maximumCachedStringLength.
Because the Vector has an inline buffer whose size is the max size of the cache, using
a FixedVector is just more efficient. It also means we don't need to store indexes in
that Vector in a separate C array. Finally, I used a struct named AtomStringWithCode to
store { AtomString, uint64 code } so we don't need separate containers for the AtomString
and the code.
Note that I added VectorTraits for the new AtomStringWithCode struct to make sure it can
get initialized via a simple memset.
This is a 0.25-0.3% progression on Speedometer according to A/B bots.
* html/parser/HTMLConstructionSite.cpp:
(WebCore::WhitespaceCache::lookup):
* html/parser/HTMLConstructionSite.h:
(WebCore::WhitespaceCache::WhitespaceCache):
Modified Paths
Diff
Modified: trunk/Source/WebCore/ChangeLog (292309 => 292310)
--- trunk/Source/WebCore/ChangeLog 2022-04-04 19:06:56 UTC (rev 292309)
+++ trunk/Source/WebCore/ChangeLog 2022-04-04 19:25:09 UTC (rev 292310)
@@ -1,3 +1,30 @@
+2022-04-04 Chris Dumez <cdu...@apple.com>
+
+ Simplify / Optimize the whitespace cache implementation
+ https://bugs.webkit.org/show_bug.cgi?id=238736
+
+ Reviewed by Sam Weinig.
+
+ Instead of using 2 C arrays of size maximumCachedStringLength + 1 Vector with an inline
+ buffer of size maximumCachedStringLength, we now used a single FixedVector of size
+ maximumCachedStringLength.
+
+ Because the Vector has an inline buffer whose size is the max size of the cache, using
+ a FixedVector is just more efficient. It also means we don't need to store indexes in
+ that Vector in a separate C array. Finally, I used a struct named AtomStringWithCode to
+ store { AtomString, uint64 code } so we don't need separate containers for the AtomString
+ and the code.
+
+ Note that I added VectorTraits for the new AtomStringWithCode struct to make sure it can
+ get initialized via a simple memset.
+
+ This is a 0.25-0.3% progression on Speedometer according to A/B bots.
+
+ * html/parser/HTMLConstructionSite.cpp:
+ (WebCore::WhitespaceCache::lookup):
+ * html/parser/HTMLConstructionSite.h:
+ (WebCore::WhitespaceCache::WhitespaceCache):
+
2022-04-04 Tim Nguyen <n...@apple.com>
Conditionally inject <attachment> styles based on runtime flag
Modified: trunk/Source/WebCore/html/parser/HTMLConstructionSite.cpp (292309 => 292310)
--- trunk/Source/WebCore/html/parser/HTMLConstructionSite.cpp 2022-04-04 19:06:56 UTC (rev 292309)
+++ trunk/Source/WebCore/html/parser/HTMLConstructionSite.cpp 2022-04-04 19:25:09 UTC (rev 292310)
@@ -887,35 +887,26 @@
return whitespaceMode == AllWhitespace || isAllWhitespace(string) ? AtomString(string) : AtomString();
uint64_t code;
- if (whitespaceMode == AllWhitespace)
+ if (whitespaceMode == AllWhitespace) {
code = codeForString<AllWhitespace>(string);
- else
+ ASSERT(code);
+ } else {
code = codeForString<WhitespaceUnknown>(string);
+ if (!code)
+ return AtomString();
+ }
- if (!code)
- return AtomString();
-
- size_t lengthIndex = length - 1;
- if (m_codes[lengthIndex] == code) {
- ASSERT(m_atoms[m_indexes[lengthIndex]] == string);
- return m_atoms[m_indexes[lengthIndex]];
+ auto& existingAtom = m_atoms[length - 1];
+ if (existingAtom.code == code) {
+ ASSERT(existingAtom.string == string);
+ return existingAtom.string;
}
if (code == overflowWhitespaceCode)
return AtomString(string);
- if (m_codes[lengthIndex]) {
- AtomString whitespaceAtom(string);
- m_codes[lengthIndex] = code;
- m_atoms[m_indexes[lengthIndex]] = whitespaceAtom;
- return whitespaceAtom;
- }
-
- AtomString whitespaceAtom(string);
- m_codes[lengthIndex] = code;
- m_indexes[lengthIndex] = m_atoms.size();
- m_atoms.append(whitespaceAtom);
- return whitespaceAtom;
+ existingAtom = { AtomString { string }, code };
+ return existingAtom.string;
}
}
Modified: trunk/Source/WebCore/html/parser/HTMLConstructionSite.h (292309 => 292310)
--- trunk/Source/WebCore/html/parser/HTMLConstructionSite.h 2022-04-04 19:06:56 UTC (rev 292309)
+++ trunk/Source/WebCore/html/parser/HTMLConstructionSite.h 2022-04-04 19:25:09 UTC (rev 292310)
@@ -30,6 +30,7 @@
#include "FragmentScriptingPermission.h"
#include "HTMLElementStack.h"
#include "HTMLFormattingElementList.h"
+#include <wtf/FixedVector.h>
#include <wtf/Noncopyable.h>
#include <wtf/RefPtr.h>
#include <wtf/SetForScope.h>
@@ -37,6 +38,17 @@
namespace WebCore {
+struct AtomStringWithCode {
+ AtomString string;
+ uint64_t code { 0 };
+};
+}
+
+namespace WTF {
+template<> struct VectorTraits<WebCore::AtomStringWithCode> : SimpleClassVectorTraits { };
+}
+
+namespace WebCore {
struct HTMLConstructionSiteTask {
enum Operation {
Insert,
@@ -228,7 +240,10 @@
class WhitespaceCache {
WTF_MAKE_FAST_ALLOCATED;
public:
- WhitespaceCache() = default;
+ WhitespaceCache()
+ : m_atoms(maximumCachedStringLength)
+ {
+ }
AtomString lookup(const String&, WhitespaceMode);
@@ -238,14 +253,7 @@
constexpr static uint64_t overflowWhitespaceCode = static_cast<uint64_t>(-1);
constexpr static size_t maximumCachedStringLength = 128;
- // Parallel arrays storing a 64 bit code and an index into m_atoms for the
- // most recently atomized whitespace-only string of a given length. The
- // indices into these two arrays are the string length minus 1, so the code
- // for a whitespace-only string of length 2 is stored at m_codes[1], etc.
- uint64_t m_codes[maximumCachedStringLength] { 0 };
- uint8_t m_indexes[maximumCachedStringLength] { 0 };
-
- Vector<AtomString, maximumCachedStringLength> m_atoms;
+ FixedVector<AtomStringWithCode> m_atoms;
};
} // namespace WebCore
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