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diff --git a/js/src/jit/StupidAllocator.h b/js/src/jit/StupidAllocator.h
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+++ b/js/src/jit/StupidAllocator.h
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+/* -*- 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_StupidAllocator_h
+#define jit_StupidAllocator_h
+
+#include "jit/RegisterAllocator.h"
+
+// Simple register allocator that only carries registers within basic blocks.
+
+namespace js {
+namespace jit {
+
+class StupidAllocator : public RegisterAllocator
+{
+    static const uint32_t MAX_REGISTERS = AnyRegister::Total;
+    static const uint32_t MISSING_ALLOCATION = UINT32_MAX;
+
+    struct AllocatedRegister {
+        AnyRegister reg;
+
+        // The type of the value in the register.
+        LDefinition::Type type;
+
+        // Virtual register this physical reg backs, or MISSING_ALLOCATION.
+        uint32_t vreg;
+
+        // id of the instruction which most recently used this register.
+        uint32_t age;
+
+        // Whether the physical register is not synced with the backing stack slot.
+        bool dirty;
+
+        void set(uint32_t vreg, LInstruction* ins = nullptr, bool dirty = false) {
+            this->vreg = vreg;
+            this->age = ins ? ins->id() : 0;
+            this->dirty = dirty;
+        }
+    };
+
+    // Active allocation for the current code position.
+    mozilla::Array<AllocatedRegister, MAX_REGISTERS> registers;
+    uint32_t registerCount;
+
+    // Type indicating an index into registers.
+    typedef uint32_t RegisterIndex;
+
+    // Information about each virtual register.
+    Vector<LDefinition*, 0, SystemAllocPolicy> virtualRegisters;
+
+  public:
+    StupidAllocator(MIRGenerator* mir, LIRGenerator* lir, LIRGraph& graph)
+      : RegisterAllocator(mir, lir, graph)
+    {
+    }
+
+    MOZ_MUST_USE bool go();
+
+  private:
+    MOZ_MUST_USE bool init();
+
+    void syncForBlockEnd(LBlock* block, LInstruction* ins);
+    void allocateForInstruction(LInstruction* ins);
+    void allocateForDefinition(LInstruction* ins, LDefinition* def);
+
+    LAllocation* stackLocation(uint32_t vreg);
+
+    RegisterIndex registerIndex(AnyRegister reg);
+
+    AnyRegister ensureHasRegister(LInstruction* ins, uint32_t vreg);
+    RegisterIndex allocateRegister(LInstruction* ins, uint32_t vreg);
+
+    void syncRegister(LInstruction* ins, RegisterIndex index);
+    void evictRegister(LInstruction* ins, RegisterIndex index);
+    void evictAliasedRegister(LInstruction* ins, RegisterIndex index);
+    void loadRegister(LInstruction* ins, uint32_t vreg, RegisterIndex index, LDefinition::Type type);
+
+    RegisterIndex findExistingRegister(uint32_t vreg);
+
+    bool allocationRequiresRegister(const LAllocation* alloc, AnyRegister reg);
+    bool registerIsReserved(LInstruction* ins, AnyRegister reg);
+};
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_StupidAllocator_h */