diff -r 000000000000 -r 6474c204b198 js/src/jit/Safepoints.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit/Safepoints.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,123 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_Safepoints_h
+#define jit_Safepoints_h
+
+#include "jit/CompactBuffer.h"
+#include "jit/shared/Assembler-shared.h"
+
+namespace js {
+namespace jit {
+
+class BitSet;
+struct SafepointNunboxEntry;
+class LAllocation;
+class LSafepoint;
+
+static const uint32_t INVALID_SAFEPOINT_OFFSET = uint32_t(-1);
+
+class SafepointWriter
+{
+    CompactBufferWriter stream_;
+    BitSet *frameSlots_;
+
+  public:
+    bool init(TempAllocator &alloc, uint32_t slotCount);
+
+  private:
+    // A safepoint entry is written in the order these functions appear.
+    uint32_t startEntry();
+
+    void writeOsiCallPointOffset(uint32_t osiPointOffset);
+    void writeGcRegs(LSafepoint *safepoint);
+    void writeGcSlots(LSafepoint *safepoint);
+    void writeValueSlots(LSafepoint *safepoint);
+
+    void writeSlotsOrElementsSlots(LSafepoint *safepoint);
+
+#ifdef JS_NUNBOX32
+    void writeNunboxParts(LSafepoint *safepoint);
+#endif
+
+    void endEntry();
+
+  public:
+    void encode(LSafepoint *safepoint);
+
+    size_t size() const {
+        return stream_.length();
+    }
+    const uint8_t *buffer() const {
+        return stream_.buffer();
+    }
+};
+
+class SafepointReader
+{
+    CompactBufferReader stream_;
+    uint32_t frameSlots_;
+    uint32_t currentSlotChunk_;
+    uint32_t nextSlotChunkNumber_;
+    uint32_t osiCallPointOffset_;
+    GeneralRegisterSet gcSpills_;
+    GeneralRegisterSet valueSpills_;
+    GeneralRegisterSet slotsOrElementsSpills_;
+    GeneralRegisterSet allGprSpills_;
+    FloatRegisterSet allFloatSpills_;
+    uint32_t nunboxSlotsRemaining_;
+    uint32_t slotsOrElementsSlotsRemaining_;
+
+  private:
+    void advanceFromGcRegs();
+    void advanceFromGcSlots();
+    void advanceFromValueSlots();
+    void advanceFromNunboxSlots();
+    bool getSlotFromBitmap(uint32_t *slot);
+
+  public:
+    SafepointReader(IonScript *script, const SafepointIndex *si);
+
+    static CodeLocationLabel InvalidationPatchPoint(IonScript *script, const SafepointIndex *si);
+
+    uint32_t osiCallPointOffset() const {
+        return osiCallPointOffset_;
+    }
+    GeneralRegisterSet gcSpills() const {
+        return gcSpills_;
+    }
+    GeneralRegisterSet slotsOrElementsSpills() const {
+        return slotsOrElementsSpills_;
+    }
+    GeneralRegisterSet valueSpills() const {
+        return valueSpills_;
+    }
+    GeneralRegisterSet allGprSpills() const {
+        return allGprSpills_;
+    }
+    FloatRegisterSet allFloatSpills() const {
+        return allFloatSpills_;
+    }
+    uint32_t osiReturnPointOffset() const;
+
+    // Returns true if a slot was read, false if there are no more slots.
+    bool getGcSlot(uint32_t *slot);
+
+    // Returns true if a slot was read, false if there are no more value slots.
+    bool getValueSlot(uint32_t *slot);
+
+    // Returns true if a nunbox slot was read, false if there are no more
+    // nunbox slots.
+    bool getNunboxSlot(LAllocation *type, LAllocation *payload);
+
+    // Returns true if a slot was read, false if there are no more slots.
+    bool getSlotsOrElementsSlot(uint32_t *slot);
+};
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_Safepoints_h */