diff -r 000000000000 -r 6474c204b198 js/src/jit/x64/Lowering-x64.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit/x64/Lowering-x64.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,71 @@
+/* -*- 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_x64_Lowering_x64_h
+#define jit_x64_Lowering_x64_h
+
+#include "jit/shared/Lowering-x86-shared.h"
+
+namespace js {
+namespace jit {
+
+class LIRGeneratorX64 : public LIRGeneratorX86Shared
+{
+  public:
+    LIRGeneratorX64(MIRGenerator *gen, MIRGraph &graph, LIRGraph &lirGraph)
+      : LIRGeneratorX86Shared(gen, graph, lirGraph)
+    { }
+
+  protected:
+    void lowerUntypedPhiInput(MPhi *phi, uint32_t inputPosition, LBlock *block, size_t lirIndex);
+    bool defineUntypedPhi(MPhi *phi, size_t lirIndex);
+
+    // Adds a use at operand |n| of a value-typed insturction.
+    bool useBox(LInstruction *lir, size_t n, MDefinition *mir,
+                LUse::Policy policy = LUse::REGISTER, bool useAtStart = false);
+    bool useBoxFixed(LInstruction *lir, size_t n, MDefinition *mir, Register reg1, Register);
+
+    // x86 has constraints on what registers can be formatted for 1-byte
+    // stores and loads; on x64 all registers are okay.
+    LAllocation useByteOpRegister(MDefinition *mir);
+    LAllocation useByteOpRegisterOrNonDoubleConstant(MDefinition *mir);
+
+    LDefinition tempToUnbox();
+
+    bool needTempForPostBarrier() { return false; }
+
+    // x64 has a scratch register, so no need for another temp for dispatch
+    // ICs.
+    LDefinition tempForDispatchCache(MIRType outputType = MIRType_None) {
+        return LDefinition::BogusTemp();
+    }
+
+  public:
+    bool visitBox(MBox *box);
+    bool visitUnbox(MUnbox *unbox);
+    bool visitReturn(MReturn *ret);
+    bool visitAsmJSUnsignedToDouble(MAsmJSUnsignedToDouble *ins);
+    bool visitAsmJSUnsignedToFloat32(MAsmJSUnsignedToFloat32 *ins);
+    bool visitAsmJSLoadHeap(MAsmJSLoadHeap *ins);
+    bool visitAsmJSStoreHeap(MAsmJSStoreHeap *ins);
+    bool visitAsmJSLoadFuncPtr(MAsmJSLoadFuncPtr *ins);
+    bool visitStoreTypedArrayElementStatic(MStoreTypedArrayElementStatic *ins);
+
+    static bool allowFloat32Optimizations() {
+        return true;
+    }
+
+    static bool allowInlineForkJoinGetSlice() {
+        return true;
+    }
+};
+
+typedef LIRGeneratorX64 LIRGeneratorSpecific;
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_x64_Lowering_x64_h */