Merge r181828 - Make UnlinkedFunctionExecutable fit in a 128-byte cell.

<https://webkit.org/b/142939> Reviewed by Mark Hahnenberg. Re-arrange the members of UnlinkedFunctionExecutable so it can fit inside a 128-byte heap cell instead of requiring a 256-byte one. Threw in a static_assert to catch anyone pushing it over the limit again. * bytecode/UnlinkedCodeBlock.cpp: (JSC::UnlinkedFunctionExecutable::UnlinkedFunctionExecutable): * bytecode/UnlinkedCodeBlock.h: (JSC::UnlinkedFunctionExecutable::functionMode):
WebKit · Mar 25, 2015 · dcda522 · dcda522
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Showing 3 changed files with 27 additions and 9 deletions.
diff --git a/Source/JavaScriptCore/ChangeLog b/Source/JavaScriptCore/ChangeLog
@@ -1,3 +1,20 @@
+2015-03-21  Andreas Kling  <akling@apple.com>
+
+        Make UnlinkedFunctionExecutable fit in a 128-byte cell.
+        <https://webkit.org/b/142939>
+
+        Reviewed by Mark Hahnenberg.
+
+        Re-arrange the members of UnlinkedFunctionExecutable so it can fit inside
+        a 128-byte heap cell instead of requiring a 256-byte one.
+
+        Threw in a static_assert to catch anyone pushing it over the limit again.
+
+        * bytecode/UnlinkedCodeBlock.cpp:
+        (JSC::UnlinkedFunctionExecutable::UnlinkedFunctionExecutable):
+        * bytecode/UnlinkedCodeBlock.h:
+        (JSC::UnlinkedFunctionExecutable::functionMode):
+
 2015-03-20  Yusuke Suzuki  <utatane.tea@gmail.com>
 
         REGRESSION (r179429): Potential Use after free in JavaScriptCore`WTF::StringImpl::ref + 83

diff --git a/Source/JavaScriptCore/bytecode/UnlinkedCodeBlock.cpp b/Source/JavaScriptCore/bytecode/UnlinkedCodeBlock.cpp
@@ -42,6 +42,8 @@
 
 namespace JSC {
 
+static_assert(sizeof(UnlinkedFunctionExecutable) <= 128, "UnlinkedFunctionExecutable should fit in a 128-byte cell.");
+
 const ClassInfo UnlinkedFunctionExecutable::s_info = { "UnlinkedFunctionExecutable", 0, 0, CREATE_METHOD_TABLE(UnlinkedFunctionExecutable) };
 const ClassInfo UnlinkedCodeBlock::s_info = { "UnlinkedCodeBlock", 0, 0, CREATE_METHOD_TABLE(UnlinkedCodeBlock) };
 const ClassInfo UnlinkedGlobalCodeBlock::s_info = { "UnlinkedGlobalCodeBlock", &Base::s_info, 0, CREATE_METHOD_TABLE(UnlinkedGlobalCodeBlock) };
@@ -81,9 +83,6 @@ unsigned UnlinkedCodeBlock::addOrFindConstant(JSValue v)
 
 UnlinkedFunctionExecutable::UnlinkedFunctionExecutable(VM* vm, Structure* structure, const SourceCode& source, FunctionBodyNode* node, UnlinkedFunctionKind kind)
     : Base(*vm, structure)
-    , m_isInStrictContext(node->isInStrictContext())
-    , m_hasCapturedVariables(false)
-    , m_isBuiltinFunction(kind == UnlinkedBuiltinFunction)
     , m_name(node->ident())
     , m_inferredName(node->inferredName())
     , m_parameters(node->parameters())
@@ -97,6 +96,9 @@ UnlinkedFunctionExecutable::UnlinkedFunctionExecutable(VM* vm, Structure* struct
     , m_typeProfilingStartOffset(node->functionKeywordStart())
     , m_typeProfilingEndOffset(node->startStartOffset() + node->source().length() - 1)
     , m_features(0)
+    , m_isInStrictContext(node->isInStrictContext())
+    , m_hasCapturedVariables(false)
+    , m_isBuiltinFunction(kind == UnlinkedBuiltinFunction)
     , m_functionMode(node->functionMode())
 {
 }

diff --git a/Source/JavaScriptCore/bytecode/UnlinkedCodeBlock.h b/Source/JavaScriptCore/bytecode/UnlinkedCodeBlock.h
@@ -108,7 +108,7 @@ class UnlinkedFunctionExecutable : public JSCell {
     }
     size_t parameterCount() const;
     bool isInStrictContext() const { return m_isInStrictContext; }
-    FunctionMode functionMode() const { return m_functionMode; }
+    FunctionMode functionMode() const { return static_cast<FunctionMode>(m_functionMode); }
     JSParserStrictness toStrictness() const
     {
         if (m_isBuiltinFunction)
@@ -166,10 +166,6 @@ class UnlinkedFunctionExecutable : public JSCell {
     WriteBarrier<UnlinkedFunctionCodeBlock> m_codeBlockForCall;
     WriteBarrier<UnlinkedFunctionCodeBlock> m_codeBlockForConstruct;
 
-    bool m_isInStrictContext : 1;
-    bool m_hasCapturedVariables : 1;
-    bool m_isBuiltinFunction : 1;
-
     Identifier m_name;
     Identifier m_inferredName;
     WriteBarrier<JSString> m_nameValue;
@@ -188,7 +184,10 @@ class UnlinkedFunctionExecutable : public JSCell {
 
     CodeFeatures m_features;
 
-    FunctionMode m_functionMode;
+    unsigned m_isInStrictContext : 1;
+    unsigned m_hasCapturedVariables : 1;
+    unsigned m_isBuiltinFunction : 1;
+    unsigned m_functionMode : 1; // FunctionMode
 
 protected:
     void finishCreation(VM& vm)