JavaScriptCore-1218.tar.gz

[apple/javascriptcore.git] / interpreter / JSStack.h

diff --git a/interpreter/JSStack.h b/interpreter/JSStack.h
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+/*
+ * Copyright (C) 2008, 2009 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1.  Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ * 2.  Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
+ *     its contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef JSStack_h
+#define JSStack_h
+
+#include "ExecutableAllocator.h"
+#include "Register.h"
+#include <wtf/Noncopyable.h>
+#include <wtf/PageReservation.h>
+#include <wtf/VMTags.h>
+
+#if !defined(NDEBUG) && !defined(ENABLE_DEBUG_JSSTACK)
+#define ENABLE_DEBUG_JSSTACK 1
+#endif
+
+namespace JSC {
+
+    class ConservativeRoots;
+    class DFGCodeBlocks;
+    class ExecState;
+    class JITStubRoutineSet;
+    class VM;
+    class LLIntOffsetsExtractor;
+
+    class JSStack {
+        WTF_MAKE_NONCOPYABLE(JSStack);
+    public:
+        enum CallFrameHeaderEntry {
+            CallFrameHeaderSize = 6,
+
+            ArgumentCount = -6,
+            CallerFrame = -5,
+            Callee = -4,
+            ScopeChain = -3,
+            ReturnPC = -2, // This is either an Instruction* or a pointer into JIT generated code stored as an Instruction*.
+            CodeBlock = -1,
+        };
+
+        static const size_t defaultCapacity = 512 * 1024;
+        static const size_t commitSize = 16 * 1024;
+        // Allow 8k of excess registers before we start trying to reap the stack
+        static const ptrdiff_t maxExcessCapacity = 8 * 1024;
+
+        JSStack(VM&, size_t capacity = defaultCapacity);
+        ~JSStack();
+        
+        void gatherConservativeRoots(ConservativeRoots&);
+        void gatherConservativeRoots(ConservativeRoots&, JITStubRoutineSet&, DFGCodeBlocks&);
+
+        Register* begin() const { return static_cast<Register*>(m_reservation.base()); }
+        Register* end() const { return m_end; }
+        size_t size() const { return end() - begin(); }
+
+        bool grow(Register*);
+        
+        static size_t committedByteCount();
+        static void initializeThreading();
+
+        Register* const * addressOfEnd() const
+        {
+            return &m_end;
+        }
+
+        Register* getTopOfFrame(CallFrame*);
+        Register* getStartOfFrame(CallFrame*);
+        Register* getTopOfStack();
+
+        CallFrame* pushFrame(CallFrame* callerFrame, class CodeBlock*,
+            JSScope*, int argsCount, JSObject* callee);
+
+        void popFrame(CallFrame*);
+
+        void enableErrorStackReserve();
+        void disableErrorStackReserve();
+
+#if ENABLE(DEBUG_JSSTACK)
+        void installFence(CallFrame*, const char *function = "", int lineNo = 0);
+        void validateFence(CallFrame*, const char *function = "", int lineNo = 0);
+        static const int FenceSize = 4;
+#else // !ENABLE(DEBUG_JSSTACK)
+        void installFence(CallFrame*, const char* = "", int = 0) { }
+        void validateFence(CallFrame*, const char* = "", int = 0) { }
+#endif // !ENABLE(DEBUG_JSSTACK)
+
+    private:
+        Register* reservationEnd() const
+        {
+            char* base = static_cast<char*>(m_reservation.base());
+            char* reservationEnd = base + m_reservation.size();
+            return reinterpret_cast_ptr<Register*>(reservationEnd);
+        }
+
+#if ENABLE(DEBUG_JSSTACK)
+        static JSValue generateFenceValue(size_t argIndex);
+        void installTrapsAfterFrame(CallFrame*);
+#else
+        void installTrapsAfterFrame(CallFrame*) { }
+#endif
+
+        bool growSlowCase(Register*);
+        void shrink(Register*);
+        void releaseExcessCapacity();
+        void addToCommittedByteCount(long);
+
+        Register* m_end;
+        Register* m_commitEnd;
+        Register* m_useableEnd;
+        PageReservation m_reservation;
+        CallFrame*& m_topCallFrame;
+
+        friend class LLIntOffsetsExtractor;
+    };
+
+    inline void JSStack::shrink(Register* newEnd)
+    {
+        if (newEnd >= m_end)
+            return;
+        m_end = newEnd;
+        if (m_end == m_reservation.base() && (m_commitEnd - begin()) >= maxExcessCapacity)
+            releaseExcessCapacity();
+    }
+
+    inline bool JSStack::grow(Register* newEnd)
+    {
+        if (newEnd <= m_end)
+            return true;
+        return growSlowCase(newEnd);
+    }
+
+} // namespace JSC
+
+#endif // JSStack_h