[JSC] Reduce sizeof(CodeBlock) from 232 to 224

https://bugs.webkit.org/show_bug.cgi?id=265508
rdar://118917365

Reviewed by Mark Lam.

This patch reduces sizeof(CodeBlock) by using float for m_previousCounter.
This is OK since BaselineExecutableCounter is anyway keeping m_totalCount as float,
so it is aligned to that precision.

* Source/JavaScriptCore/bytecode/CodeBlock.cpp:
(JSC::CodeBlock::finalizeUnconditionally):
* Source/JavaScriptCore/bytecode/CodeBlock.h:

Canonical link: https://commits.webkit.org/271273@main

Source/JavaScriptCore/bytecode/CodeBlock.cpp

@@ -1622,7 +1622,7 @@ void CodeBlock::finalizeUnconditionally(VM& vm, CollectionScope)
         if (!VM::useUnlinkedCodeBlockJettisoning())
             return;
         JITCode* jitCode = m_jitCode.get();
-        double count = 0;
+        float count = 0;
         bool alwaysActive = false;
         switch (JITCode::jitTypeFor(jitCode)) {
         case JITType::None:

Source/JavaScriptCore/bytecode/CodeBlock.h

@@ -953,6 +953,8 @@ class CodeBlock : public JSCell {
 
     const void* const m_instructionsRawPointer { nullptr };
     SentinelLinkedList<CallLinkInfoBase, PackedRawSentinelNode<CallLinkInfoBase>> m_incomingCalls;
+    uint16_t m_optimizationDelayCounter { 0 };
+    uint16_t m_reoptimizationRetryCounter { 0 };
     StructureWatchpointMap m_llintGetByIdWatchpointMap;
     RefPtr<JITCode> m_jitCode;
 #if ENABLE(JIT)
@@ -980,11 +982,9 @@ class CodeBlock : public JSCell {
 
     BaselineExecutionCounter m_jitExecuteCounter;
 
-    uint16_t m_optimizationDelayCounter { 0 };
-    uint16_t m_reoptimizationRetryCounter { 0 };
+    float m_previousCounter { 0 };
 
     ApproximateTime m_creationTime;
-    double m_previousCounter { 0 };
 
     std::unique_ptr<RareData> m_rareData;
 
@@ -995,7 +995,7 @@ class CodeBlock : public JSCell {
 };
 /* This check is for normal Release builds; ASSERT_ENABLED changes the size. */
 #if defined(NDEBUG) && !defined(ASSERT_ENABLED) && COMPILER(GCC_COMPATIBLE)
-static_assert(sizeof(CodeBlock) <= 240, "Keep it small for memory saving");
+static_assert(sizeof(CodeBlock) <= 224, "Keep it small for memory saving");
 #endif
 
 template <typename ExecutableType>