Changeset 292714 in webkit for trunk/Source/JavaScriptCore/assembler/AbstractMacroAssembler.cpp

Timestamp:

Apr 11, 2022, 1:10:44 PM (3 years ago)

Author:

[email protected]

Message:

[JSC] Reduce use of unnecessary cryptographicallyRandom numbers
​https://bugs.webkit.org/show_bug.cgi?id=239026

Reviewed by Saam Barati.

Source/JavaScriptCore:

This patch removes cryptographically random calls in some of super hot critical path.
MarkedBlock's use is very hot and it appears on Speedometer2 artrace. But this is just
a random shuffling of freelist, and WeakRandom is enough for that. This patch replaces
them with WeakRandom. It offers 0.3% improvement in Speedometer2.

• assembler/AbstractMacroAssembler.cpp:

(JSC::AbstractMacroAssemblerBase::initializeRandom):
(WTF::printInternal):

• assembler/AbstractMacroAssembler.h:

(JSC::AbstractMacroAssemblerBase::random):
(JSC::AbstractMacroAssembler::AbstractMacroAssembler):
(JSC::AbstractMacroAssembler::random): Deleted.

• b3/air/AirCode.cpp:

(JSC::B3::Air::Code::Code):

• b3/air/AirCode.h:

(JSC::B3::Air::Code::weakRandom): Deleted.

• heap/MarkedBlockInlines.h:

(JSC::MarkedBlock::Handle::specializedSweep):

• runtime/VM.cpp:

(JSC::VM::VM):

• runtime/VM.h:

(JSC::VM::heapRandom):

Source/WebCore:

We use createVersion4UUIDStringWeak since there is no need to use cryptographically random numbers for KeyframeEffect names.

• animation/KeyframeEffect.cpp:

(WebCore::KeyframeEffect::copyPropertiesFromSource):
(WebCore::KeyframeEffect::updateBlendingKeyframes):
(WebCore::KeyframeEffect::computeCSSTransitionBlendingKeyframes):

Source/WTF:

We add createVersion4UUIDStringWeak, which can generate UUID with WeakRandom numbers.

• wtf/UUID.cpp:

(WTF::convertRandomUInt128ToUUIDVersion4):
(WTF::generateCryptographicallyRandomUUIDVersion4):
(WTF::generateWeakRandomUUIDVersion4):
(WTF::UUID::UUID):
(WTF::createVersion4UUIDStringWeak):

• wtf/UUID.h:
• wtf/WeakRandom.h:

File:

• trunk/Source/JavaScriptCore/assembler/AbstractMacroAssembler.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/assembler/AbstractMacroAssembler.cpp

@@ -31 +31 @@
 #include <wtf/PrintStream.h>
 
+namespace JSC {
+
+void AbstractMacroAssemblerBase::initializeRandom()
+{
+    // No strong cryptographic characteristics are necessary.
+    static std::once_flag onceKey;
+    static uint32_t globalCounter;
+    std::call_once(onceKey, [&] {
+        globalCounter = cryptographicallyRandomNumber();
+    });
+    ASSERT(!m_randomSource);
+    m_randomSource.emplace(globalCounter++);
+}
+
+}
+
 namespace WTF {
 
-using namespace JSC;
-
-void printInternal(PrintStream& out, AbstractMacroAssemblerBase::StatusCondition condition)
+void printInternal(PrintStream& out, JSC::AbstractMacroAssemblerBase::StatusCondition condition)
 {
     switch (condition) {
-    case AbstractMacroAssemblerBase::Success:
+    case JSC::AbstractMacroAssemblerBase::Success:
         out.print("Success");
         return;
-    case AbstractMacroAssemblerBase::Failure:
+    case JSC::AbstractMacroAssemblerBase::Failure:
         out.print("Failure");
         return;