BuiltinExecutables keeps finalized Weaks around, pinning WeakBlocks.

<https://webkit.org/b/142460>

Reviewed by Geoffrey Garen.

Make BuiltinExecutables a WeakHandleOwner so it can clear out its respective Weak members
if and when their pointees get garbage collected.

This fixes an issue I've seen locally where a WeakBlock is pinned down by a single one of
these Weak<BuiltinExecutables>.

* builtins/BuiltinExecutables.h: Make BuiltinExecutables inherit from WeakHandleOwner.

* builtins/BuiltinExecutables.cpp:
(JSC::BuiltinExecutables::finalize): Clear out the relevant member pointer when it's been
garbage collected. We use the WeakImpl's "context" field to pass the address of the member.


Canonical link: https://commits.webkit.org/160506@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@181248 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/JavaScriptCore/ChangeLog

@@ -1,3 +1,22 @@
+2015-03-08  Andreas Kling  <akling@apple.com>
+
+        BuiltinExecutables keeps finalized Weaks around, pinning WeakBlocks.
+        <https://webkit.org/b/142460>
+
+        Reviewed by Geoffrey Garen.
+
+        Make BuiltinExecutables a WeakHandleOwner so it can clear out its respective Weak members
+        if and when their pointees get garbage collected.
+
+        This fixes an issue I've seen locally where a WeakBlock is pinned down by a single one of
+        these Weak<BuiltinExecutables>.
+
+        * builtins/BuiltinExecutables.h: Make BuiltinExecutables inherit from WeakHandleOwner.
+
+        * builtins/BuiltinExecutables.cpp:
+        (JSC::BuiltinExecutables::finalize): Clear out the relevant member pointer when it's been
+        garbage collected. We use the WeakImpl's "context" field to pass the address of the member.
+
 2015-03-07  Geoffrey Garen  <ggaren@apple.com>
 
         Use FastMalloc (bmalloc) instead of BlockAllocator for GC pages

Source/JavaScriptCore/builtins/BuiltinExecutables.cpp

@@ -83,11 +83,16 @@ UnlinkedFunctionExecutable* BuiltinExecutables::createBuiltinExecutable(const So
     return functionExecutable;
 }
 
+void BuiltinExecutables::finalize(Handle<Unknown>, void* context)
+{
+    static_cast<Weak<UnlinkedFunctionExecutable>*>(context)->clear();
+}
+
 #define DEFINE_BUILTIN_EXECUTABLES(name, functionName, length) \
 UnlinkedFunctionExecutable* BuiltinExecutables::name##Executable() \
 {\
     if (!m_##name##Executable)\
-        m_##name##Executable = createBuiltinExecutable(m_##name##Source, m_vm.propertyNames->builtinNames().functionName##PublicName());\
+        m_##name##Executable = Weak<UnlinkedFunctionExecutable>(createBuiltinExecutable(m_##name##Source, m_vm.propertyNames->builtinNames().functionName##PublicName()), this, &m_##name##Executable);\
     return m_##name##Executable.get();\
 }
 JSC_FOREACH_BUILTIN(DEFINE_BUILTIN_EXECUTABLES)

Source/JavaScriptCore/builtins/BuiltinExecutables.h

@@ -29,14 +29,15 @@
 #include "JSCBuiltins.h"
 #include "SourceCode.h"
 #include "Weak.h"
+#include "WeakHandleOwner.h"
 
 namespace JSC {
 
 class UnlinkedFunctionExecutable;
 class Identifier;
 class VM;
 
-class BuiltinExecutables {
+class BuiltinExecutables final: private WeakHandleOwner {
     WTF_MAKE_FAST_ALLOCATED;
 public:
     explicit BuiltinExecutables(VM&);
@@ -49,6 +50,8 @@ const SourceCode& name##Source() { return m_##name##Source; }
 #undef EXPOSE_BUILTIN_SOURCES
 
 private:
+    void finalize(Handle<Unknown>, void* context) override;
+
     VM& m_vm;
     UnlinkedFunctionExecutable* createBuiltinExecutable(const SourceCode&, const Identifier&);
 #define DECLARE_BUILTIN_SOURCE_MEMBERS(name, functionName, length)\