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

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.h (modified) (2 diffs)

trunk/Source/JavaScriptCore/assembler/AbstractMacroAssembler.h

@@ -75 +75 @@
         return Success;
     }
+
+protected:
+    uint32_t random()
+    {
+        if (!m_randomSource)
+            initializeRandom();
+        return m_randomSource->getUint32();
+    }
+
+private:
+    JS_EXPORT_PRIVATE void initializeRandom();
+
+    std::optional<WeakRandom> m_randomSource;
 };
 
@@ -1008 +1021 @@
 protected:
     AbstractMacroAssembler()
-        : m_randomSource(0)
-        , m_assembler()
+        : m_assembler()
     {
         invalidateAllTempRegisters();
     }
 
-    uint32_t random()
-    {
-        if (!m_randomSourceIsInitialized) {
-            m_randomSourceIsInitialized = true;
-            m_randomSource.setSeed(cryptographicallyRandomNumber());
-        }
-        return m_randomSource.getUint32();
-    }
-
-    bool m_randomSourceIsInitialized { false };
-    WeakRandom m_randomSource;
 public:
     AssemblerType m_assembler;