webkitgtk-2.4.11webkitgtk-2.4.11

1 files changed, 40 insertions, 26 deletions

diff --git a/Source/JavaScriptCore/runtime/VMEntryScope.cpp b/Source/JavaScriptCore/runtime/VMEntryScope.cpp
index 8241dece2..47782ce3b 100644
--- a/Source/JavaScriptCore/runtime/VMEntryScope.cpp
+++ b/Source/JavaScriptCore/runtime/VMEntryScope.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2013-2015 Apple Inc. All rights reserved.
+ * Copyright (C) 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -27,55 +27,69 @@
 #include "VMEntryScope.h"
 
 #include "Debugger.h"
-#include "Options.h"
-#include "SamplingProfiler.h"
 #include "VM.h"
-#include "Watchdog.h"
 #include <wtf/StackBounds.h>
 
 namespace JSC {
 
 VMEntryScope::VMEntryScope(VM& vm, JSGlobalObject* globalObject)
     : m_vm(vm)
+    , m_stack(wtfThreadData().stack())
     , m_globalObject(globalObject)
+    , m_prev(vm.entryScope)
+    , m_prevStackLimit(vm.stackLimit())
+    , m_recompilationNeeded(false)
 {
-    ASSERT(wtfThreadData().stack().isGrowingDownward());
     if (!vm.entryScope) {
+#if ENABLE(ASSEMBLER)
+        if (ExecutableAllocator::underMemoryPressure())
+            vm.heap.deleteAllCompiledCode();
+#endif
         vm.entryScope = this;
 
         // Reset the date cache between JS invocations to force the VM to
-        // observe time zone changes.
+        // observe time xone changes.
         vm.resetDateCache();
-
-        if (vm.watchdog())
-            vm.watchdog()->enteredVM();
-
-#if ENABLE(SAMPLING_PROFILER)
-        if (SamplingProfiler* samplingProfiler = vm.samplingProfiler())
-            samplingProfiler->noticeVMEntry();
-#endif
     }
+    // Clear the exception stack between entries
+    vm.clearExceptionStack();
 
-    vm.clearLastException();
+    void* limit = m_stack.recursionLimit(requiredCapacity());
+    vm.setStackLimit(limit);
 }
 
-void VMEntryScope::addDidPopListener(std::function<void ()> listener)
+VMEntryScope::~VMEntryScope()
 {
-    m_didPopListeners.append(listener);
+    m_vm.entryScope = m_prev;
+    m_vm.setStackLimit(m_prevStackLimit);
+
+    if (m_recompilationNeeded) {
+        if (m_vm.entryScope)
+            m_vm.entryScope->setRecompilationNeeded(true);
+        else {
+            if (Debugger* debugger = m_globalObject->debugger())
+                debugger->recompileAllJSFunctions(&m_vm);
+        }
+    }
 }
 
-VMEntryScope::~VMEntryScope()
+size_t VMEntryScope::requiredCapacity() const
 {
-    if (m_vm.entryScope != this)
-        return;
-
-    if (m_vm.watchdog())
-        m_vm.watchdog()->exitedVM();
+    Interpreter* interpreter = m_vm.interpreter;
 
-    m_vm.entryScope = nullptr;
+    // We require a smaller stack budget for the error stack. This is to allow
+    // some minimal JS execution to proceed and do the work of throwing a stack
+    // overflow error if needed. In contrast, arbitrary JS code will require the
+    // more generous stack budget in order to proceed.
+    //
+    // These sizes were derived from the stack usage of a number of sites when
+    // layout occurs when we've already consumed most of the C stack.
+    const size_t requiredStack = 128 * KB;
+    const size_t errorModeRequiredStack = 64 * KB;
 
-    for (auto& listener : m_didPopListeners)
-        listener();
+    size_t requiredCapacity = interpreter->isInErrorHandlingMode() ? errorModeRequiredStack : requiredStack;
+    RELEASE_ASSERT(m_stack.size() >= requiredCapacity);
+    return requiredCapacity;
 }
 
 } // namespace JSC