Merge WebKit at r75315: Initial merge by git.

Change-Id: I570314b346ce101c935ed22a626b48c2af266b84

1 files changed, 2100 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/assembler/X86Assembler.h b/Source/JavaScriptCore/assembler/X86Assembler.h
new file mode 100644
index 0000000..b352ad4
--- /dev/null
+++ b/Source/JavaScriptCore/assembler/X86Assembler.h
@@ -0,0 +1,2100 @@
+/*
+ * Copyright (C) 2008 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 INC. OR
+ * 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 X86Assembler_h
+#define X86Assembler_h
+
+#if ENABLE(ASSEMBLER) && (CPU(X86) || CPU(X86_64))
+
+#include "AssemblerBuffer.h"
+#include <stdint.h>
+#include <wtf/Assertions.h>
+#include <wtf/Vector.h>
+
+namespace JSC {
+
+inline bool CAN_SIGN_EXTEND_8_32(int32_t value) { return value == (int32_t)(signed char)value; }
+
+namespace X86Registers {
+    typedef enum {
+        eax,
+        ecx,
+        edx,
+        ebx,
+        esp,
+        ebp,
+        esi,
+        edi,
+
+#if CPU(X86_64)
+        r8,
+        r9,
+        r10,
+        r11,
+        r12,
+        r13,
+        r14,
+        r15,
+#endif
+    } RegisterID;
+
+    typedef enum {
+        xmm0,
+        xmm1,
+        xmm2,
+        xmm3,
+        xmm4,
+        xmm5,
+        xmm6,
+        xmm7,
+    } XMMRegisterID;
+}
+
+class X86Assembler {
+public:
+    typedef X86Registers::RegisterID RegisterID;
+    typedef X86Registers::XMMRegisterID XMMRegisterID;
+    typedef XMMRegisterID FPRegisterID;
+
+    typedef enum {
+        ConditionO,
+        ConditionNO,
+        ConditionB,
+        ConditionAE,
+        ConditionE,
+        ConditionNE,
+        ConditionBE,
+        ConditionA,
+        ConditionS,
+        ConditionNS,
+        ConditionP,
+        ConditionNP,
+        ConditionL,
+        ConditionGE,
+        ConditionLE,
+        ConditionG,
+
+        ConditionC  = ConditionB,
+        ConditionNC = ConditionAE,
+    } Condition;
+
+private:
+    typedef enum {
+        OP_ADD_EvGv                     = 0x01,
+        OP_ADD_GvEv                     = 0x03,
+        OP_OR_EvGv                      = 0x09,
+        OP_OR_GvEv                      = 0x0B,
+        OP_2BYTE_ESCAPE                 = 0x0F,
+        OP_AND_EvGv                     = 0x21,
+        OP_AND_GvEv                     = 0x23,
+        OP_SUB_EvGv                     = 0x29,
+        OP_SUB_GvEv                     = 0x2B,
+        PRE_PREDICT_BRANCH_NOT_TAKEN    = 0x2E,
+        OP_XOR_EvGv                     = 0x31,
+        OP_XOR_GvEv                     = 0x33,
+        OP_CMP_EvGv                     = 0x39,
+        OP_CMP_GvEv                     = 0x3B,
+#if CPU(X86_64)
+        PRE_REX                         = 0x40,
+#endif
+        OP_PUSH_EAX                     = 0x50,
+        OP_POP_EAX                      = 0x58,
+#if CPU(X86_64)
+        OP_MOVSXD_GvEv                  = 0x63,
+#endif
+        PRE_OPERAND_SIZE                = 0x66,
+        PRE_SSE_66                      = 0x66,
+        OP_PUSH_Iz                      = 0x68,
+        OP_IMUL_GvEvIz                  = 0x69,
+        OP_GROUP1_EbIb                  = 0x80,
+        OP_GROUP1_EvIz                  = 0x81,
+        OP_GROUP1_EvIb                  = 0x83,
+        OP_TEST_EvGv                    = 0x85,
+        OP_XCHG_EvGv                    = 0x87,
+        OP_MOV_EvGv                     = 0x89,
+        OP_MOV_GvEv                     = 0x8B,
+        OP_LEA                          = 0x8D,
+        OP_GROUP1A_Ev                   = 0x8F,
+        OP_CDQ                          = 0x99,
+        OP_MOV_EAXOv                    = 0xA1,
+        OP_MOV_OvEAX                    = 0xA3,
+        OP_MOV_EAXIv                    = 0xB8,
+        OP_GROUP2_EvIb                  = 0xC1,
+        OP_RET                          = 0xC3,
+        OP_GROUP11_EvIz                 = 0xC7,
+        OP_INT3                         = 0xCC,
+        OP_GROUP2_Ev1                   = 0xD1,
+        OP_GROUP2_EvCL                  = 0xD3,
+        OP_CALL_rel32                   = 0xE8,
+        OP_JMP_rel32                    = 0xE9,
+        PRE_SSE_F2                      = 0xF2,
+        OP_HLT                          = 0xF4,
+        OP_GROUP3_EbIb                  = 0xF6,
+        OP_GROUP3_Ev                    = 0xF7,
+        OP_GROUP3_EvIz                  = 0xF7, // OP_GROUP3_Ev has an immediate, when instruction is a test. 
+        OP_GROUP5_Ev                    = 0xFF,
+    } OneByteOpcodeID;
+
+    typedef enum {
+        OP2_MOVSD_VsdWsd    = 0x10,
+        OP2_MOVSD_WsdVsd    = 0x11,
+        OP2_CVTSI2SD_VsdEd  = 0x2A,
+        OP2_CVTTSD2SI_GdWsd = 0x2C,
+        OP2_UCOMISD_VsdWsd  = 0x2E,
+        OP2_ADDSD_VsdWsd    = 0x58,
+        OP2_MULSD_VsdWsd    = 0x59,
+        OP2_SUBSD_VsdWsd    = 0x5C,
+        OP2_DIVSD_VsdWsd    = 0x5E,
+        OP2_SQRTSD_VsdWsd   = 0x51,
+        OP2_XORPD_VpdWpd    = 0x57,
+        OP2_MOVD_VdEd       = 0x6E,
+        OP2_MOVD_EdVd       = 0x7E,
+        OP2_JCC_rel32       = 0x80,
+        OP_SETCC            = 0x90,
+        OP2_IMUL_GvEv       = 0xAF,
+        OP2_MOVZX_GvEb      = 0xB6,
+        OP2_MOVZX_GvEw      = 0xB7,
+        OP2_PEXTRW_GdUdIb   = 0xC5,
+    } TwoByteOpcodeID;
+
+    TwoByteOpcodeID jccRel32(Condition cond)
+    {
+        return (TwoByteOpcodeID)(OP2_JCC_rel32 + cond);
+    }
+
+    TwoByteOpcodeID setccOpcode(Condition cond)
+    {
+        return (TwoByteOpcodeID)(OP_SETCC + cond);
+    }
+
+    typedef enum {
+        GROUP1_OP_ADD = 0,
+        GROUP1_OP_OR  = 1,
+        GROUP1_OP_ADC = 2,
+        GROUP1_OP_AND = 4,
+        GROUP1_OP_SUB = 5,
+        GROUP1_OP_XOR = 6,
+        GROUP1_OP_CMP = 7,
+
+        GROUP1A_OP_POP = 0,
+
+        GROUP2_OP_SHL = 4,
+        GROUP2_OP_SHR = 5,
+        GROUP2_OP_SAR = 7,
+
+        GROUP3_OP_TEST = 0,
+        GROUP3_OP_NOT  = 2,
+        GROUP3_OP_NEG  = 3,
+        GROUP3_OP_IDIV = 7,
+
+        GROUP5_OP_CALLN = 2,
+        GROUP5_OP_JMPN  = 4,
+        GROUP5_OP_PUSH  = 6,
+
+        GROUP11_MOV = 0,
+    } GroupOpcodeID;
+    
+    class X86InstructionFormatter;
+public:
+
+    class JmpSrc {
+        friend class X86Assembler;
+        friend class X86InstructionFormatter;
+    public:
+        JmpSrc()
+            : m_offset(-1)
+        {
+        }
+
+    private:
+        JmpSrc(int offset)
+            : m_offset(offset)
+        {
+        }
+
+        int m_offset;
+    };
+    
+    class JmpDst {
+        friend class X86Assembler;
+        friend class X86InstructionFormatter;
+    public:
+        JmpDst()
+            : m_offset(-1)
+            , m_used(false)
+        {
+        }
+
+        bool isUsed() const { return m_used; }
+        bool isSet() const { return (m_offset != -1); }
+        void used() { m_used = true; }
+    private:
+        JmpDst(int offset)
+            : m_offset(offset)
+            , m_used(false)
+        {
+            ASSERT(m_offset == offset);
+        }
+
+        int m_offset : 31;
+        bool m_used : 1;
+    };
+
+    X86Assembler()
+    {
+    }
+
+    size_t size() const { return m_formatter.size(); }
+
+    // Stack operations:
+
+    void push_r(RegisterID reg)
+    {
+        m_formatter.oneByteOp(OP_PUSH_EAX, reg);
+    }
+
+    void pop_r(RegisterID reg)
+    {
+        m_formatter.oneByteOp(OP_POP_EAX, reg);
+    }
+
+    void push_i32(int imm)
+    {
+        m_formatter.oneByteOp(OP_PUSH_Iz);
+        m_formatter.immediate32(imm);
+    }
+
+    void push_m(int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_GROUP5_Ev, GROUP5_OP_PUSH, base, offset);
+    }
+
+    void pop_m(int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_GROUP1A_Ev, GROUP1A_OP_POP, base, offset);
+    }
+
+    // Arithmetic operations:
+
+#if !CPU(X86_64)
+    void adcl_im(int imm, void* addr)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_ADC, addr);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_ADC, addr);
+            m_formatter.immediate32(imm);
+        }
+    }
+#endif
+
+    void addl_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_ADD_EvGv, src, dst);
+    }
+
+    void addl_mr(int offset, RegisterID base, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_ADD_GvEv, dst, base, offset);
+    }
+
+    void addl_rm(RegisterID src, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_ADD_EvGv, src, base, offset);
+    }
+
+    void addl_ir(int imm, RegisterID dst)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_ADD, dst);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_ADD, dst);
+            m_formatter.immediate32(imm);
+        }
+    }
+
+    void addl_im(int imm, int offset, RegisterID base)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_ADD, base, offset);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_ADD, base, offset);
+            m_formatter.immediate32(imm);
+        }
+    }
+
+#if CPU(X86_64)
+    void addq_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_ADD_EvGv, src, dst);
+    }
+
+    void addq_ir(int imm, RegisterID dst)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIb, GROUP1_OP_ADD, dst);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIz, GROUP1_OP_ADD, dst);
+            m_formatter.immediate32(imm);
+        }
+    }
+
+    void addq_im(int imm, int offset, RegisterID base)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIb, GROUP1_OP_ADD, base, offset);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIz, GROUP1_OP_ADD, base, offset);
+            m_formatter.immediate32(imm);
+        }
+    }
+#else
+    void addl_im(int imm, void* addr)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_ADD, addr);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_ADD, addr);
+            m_formatter.immediate32(imm);
+        }
+    }
+#endif
+
+    void andl_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_AND_EvGv, src, dst);
+    }
+
+    void andl_mr(int offset, RegisterID base, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_AND_GvEv, dst, base, offset);
+    }
+
+    void andl_rm(RegisterID src, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_AND_EvGv, src, base, offset);
+    }
+
+    void andl_ir(int imm, RegisterID dst)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_AND, dst);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_AND, dst);
+            m_formatter.immediate32(imm);
+        }
+    }
+
+    void andl_im(int imm, int offset, RegisterID base)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_AND, base, offset);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_AND, base, offset);
+            m_formatter.immediate32(imm);
+        }
+    }
+
+#if CPU(X86_64)
+    void andq_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_AND_EvGv, src, dst);
+    }
+
+    void andq_ir(int imm, RegisterID dst)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIb, GROUP1_OP_AND, dst);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIz, GROUP1_OP_AND, dst);
+            m_formatter.immediate32(imm);
+        }
+    }
+#else
+    void andl_im(int imm, void* addr)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_AND, addr);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_AND, addr);
+            m_formatter.immediate32(imm);
+        }
+    }
+#endif
+
+    void negl_r(RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_GROUP3_Ev, GROUP3_OP_NEG, dst);
+    }
+
+    void negl_m(int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_GROUP3_Ev, GROUP3_OP_NEG, base, offset);
+    }
+
+    void notl_r(RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_GROUP3_Ev, GROUP3_OP_NOT, dst);
+    }
+
+    void notl_m(int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_GROUP3_Ev, GROUP3_OP_NOT, base, offset);
+    }
+
+    void orl_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_OR_EvGv, src, dst);
+    }
+
+    void orl_mr(int offset, RegisterID base, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_OR_GvEv, dst, base, offset);
+    }
+
+    void orl_rm(RegisterID src, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_OR_EvGv, src, base, offset);
+    }
+
+    void orl_ir(int imm, RegisterID dst)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_OR, dst);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_OR, dst);
+            m_formatter.immediate32(imm);
+        }
+    }
+
+    void orl_im(int imm, int offset, RegisterID base)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_OR, base, offset);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_OR, base, offset);
+            m_formatter.immediate32(imm);
+        }
+    }
+
+#if CPU(X86_64)
+    void orq_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_OR_EvGv, src, dst);
+    }
+
+    void orq_ir(int imm, RegisterID dst)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIb, GROUP1_OP_OR, dst);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIz, GROUP1_OP_OR, dst);
+            m_formatter.immediate32(imm);
+        }
+    }
+#else
+    void orl_im(int imm, void* addr)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_OR, addr);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_OR, addr);
+            m_formatter.immediate32(imm);
+        }
+    }
+#endif
+
+    void subl_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_SUB_EvGv, src, dst);
+    }
+
+    void subl_mr(int offset, RegisterID base, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_SUB_GvEv, dst, base, offset);
+    }
+
+    void subl_rm(RegisterID src, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_SUB_EvGv, src, base, offset);
+    }
+
+    void subl_ir(int imm, RegisterID dst)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_SUB, dst);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_SUB, dst);
+            m_formatter.immediate32(imm);
+        }
+    }
+    
+    void subl_im(int imm, int offset, RegisterID base)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_SUB, base, offset);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_SUB, base, offset);
+            m_formatter.immediate32(imm);
+        }
+    }
+
+#if CPU(X86_64)
+    void subq_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_SUB_EvGv, src, dst);
+    }
+
+    void subq_ir(int imm, RegisterID dst)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIb, GROUP1_OP_SUB, dst);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIz, GROUP1_OP_SUB, dst);
+            m_formatter.immediate32(imm);
+        }
+    }
+#else
+    void subl_im(int imm, void* addr)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_SUB, addr);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_SUB, addr);
+            m_formatter.immediate32(imm);
+        }
+    }
+#endif
+
+    void xorl_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_XOR_EvGv, src, dst);
+    }
+
+    void xorl_mr(int offset, RegisterID base, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_XOR_GvEv, dst, base, offset);
+    }
+
+    void xorl_rm(RegisterID src, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_XOR_EvGv, src, base, offset);
+    }
+
+    void xorl_im(int imm, int offset, RegisterID base)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_XOR, base, offset);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_XOR, base, offset);
+            m_formatter.immediate32(imm);
+        }
+    }
+
+    void xorl_ir(int imm, RegisterID dst)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_XOR, dst);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_XOR, dst);
+            m_formatter.immediate32(imm);
+        }
+    }
+
+#if CPU(X86_64)
+    void xorq_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_XOR_EvGv, src, dst);
+    }
+
+    void xorq_ir(int imm, RegisterID dst)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIb, GROUP1_OP_XOR, dst);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIz, GROUP1_OP_XOR, dst);
+            m_formatter.immediate32(imm);
+        }
+    }
+#endif
+
+    void sarl_i8r(int imm, RegisterID dst)
+    {
+        if (imm == 1)
+            m_formatter.oneByteOp(OP_GROUP2_Ev1, GROUP2_OP_SAR, dst);
+        else {
+            m_formatter.oneByteOp(OP_GROUP2_EvIb, GROUP2_OP_SAR, dst);
+            m_formatter.immediate8(imm);
+        }
+    }
+
+    void sarl_CLr(RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_GROUP2_EvCL, GROUP2_OP_SAR, dst);
+    }
+    
+    void shrl_i8r(int imm, RegisterID dst)
+    {
+        if (imm == 1)
+            m_formatter.oneByteOp(OP_GROUP2_Ev1, GROUP2_OP_SHR, dst);
+        else {
+            m_formatter.oneByteOp(OP_GROUP2_EvIb, GROUP2_OP_SHR, dst);
+            m_formatter.immediate8(imm);
+        }
+    }
+    
+    void shrl_CLr(RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_GROUP2_EvCL, GROUP2_OP_SHR, dst);
+    }
+
+    void shll_i8r(int imm, RegisterID dst)
+    {
+        if (imm == 1)
+            m_formatter.oneByteOp(OP_GROUP2_Ev1, GROUP2_OP_SHL, dst);
+        else {
+            m_formatter.oneByteOp(OP_GROUP2_EvIb, GROUP2_OP_SHL, dst);
+            m_formatter.immediate8(imm);
+        }
+    }
+
+    void shll_CLr(RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_GROUP2_EvCL, GROUP2_OP_SHL, dst);
+    }
+
+#if CPU(X86_64)
+    void sarq_CLr(RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_GROUP2_EvCL, GROUP2_OP_SAR, dst);
+    }
+
+    void sarq_i8r(int imm, RegisterID dst)
+    {
+        if (imm == 1)
+            m_formatter.oneByteOp64(OP_GROUP2_Ev1, GROUP2_OP_SAR, dst);
+        else {
+            m_formatter.oneByteOp64(OP_GROUP2_EvIb, GROUP2_OP_SAR, dst);
+            m_formatter.immediate8(imm);
+        }
+    }
+#endif
+
+    void imull_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.twoByteOp(OP2_IMUL_GvEv, dst, src);
+    }
+
+    void imull_mr(int offset, RegisterID base, RegisterID dst)
+    {
+        m_formatter.twoByteOp(OP2_IMUL_GvEv, dst, base, offset);
+    }
+
+    void imull_i32r(RegisterID src, int32_t value, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_IMUL_GvEvIz, dst, src);
+        m_formatter.immediate32(value);
+    }
+
+    void idivl_r(RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_GROUP3_Ev, GROUP3_OP_IDIV, dst);
+    }
+
+    // Comparisons:
+
+    void cmpl_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_CMP_EvGv, src, dst);
+    }
+
+    void cmpl_rm(RegisterID src, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_CMP_EvGv, src, base, offset);
+    }
+
+    void cmpl_mr(int offset, RegisterID base, RegisterID src)
+    {
+        m_formatter.oneByteOp(OP_CMP_GvEv, src, base, offset);
+    }
+
+    void cmpl_ir(int imm, RegisterID dst)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_CMP, dst);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_CMP, dst);
+            m_formatter.immediate32(imm);
+        }
+    }
+
+    void cmpl_ir_force32(int imm, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_CMP, dst);
+        m_formatter.immediate32(imm);
+    }
+    
+    void cmpl_im(int imm, int offset, RegisterID base)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_CMP, base, offset);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_CMP, base, offset);
+            m_formatter.immediate32(imm);
+        }
+    }
+    
+    void cmpb_im(int imm, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_GROUP1_EbIb, GROUP1_OP_CMP, base, offset);
+        m_formatter.immediate8(imm);
+    }
+    
+    void cmpb_im(int imm, int offset, RegisterID base, RegisterID index, int scale)
+    {
+        m_formatter.oneByteOp(OP_GROUP1_EbIb, GROUP1_OP_CMP, base, index, scale, offset);
+        m_formatter.immediate8(imm);
+    }
+
+    void cmpl_im(int imm, int offset, RegisterID base, RegisterID index, int scale)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_CMP, base, index, scale, offset);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_CMP, base, index, scale, offset);
+            m_formatter.immediate32(imm);
+        }
+    }
+
+    void cmpl_im_force32(int imm, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_CMP, base, offset);
+        m_formatter.immediate32(imm);
+    }
+
+#if CPU(X86_64)
+    void cmpq_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_CMP_EvGv, src, dst);
+    }
+
+    void cmpq_rm(RegisterID src, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp64(OP_CMP_EvGv, src, base, offset);
+    }
+
+    void cmpq_mr(int offset, RegisterID base, RegisterID src)
+    {
+        m_formatter.oneByteOp64(OP_CMP_GvEv, src, base, offset);
+    }
+
+    void cmpq_ir(int imm, RegisterID dst)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIb, GROUP1_OP_CMP, dst);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIz, GROUP1_OP_CMP, dst);
+            m_formatter.immediate32(imm);
+        }
+    }
+
+    void cmpq_im(int imm, int offset, RegisterID base)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIb, GROUP1_OP_CMP, base, offset);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIz, GROUP1_OP_CMP, base, offset);
+            m_formatter.immediate32(imm);
+        }
+    }
+
+    void cmpq_im(int imm, int offset, RegisterID base, RegisterID index, int scale)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIb, GROUP1_OP_CMP, base, index, scale, offset);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp64(OP_GROUP1_EvIz, GROUP1_OP_CMP, base, index, scale, offset);
+            m_formatter.immediate32(imm);
+        }
+    }
+#else
+    void cmpl_rm(RegisterID reg, void* addr)
+    {
+        m_formatter.oneByteOp(OP_CMP_EvGv, reg, addr);
+    }
+
+    void cmpl_im(int imm, void* addr)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_CMP, addr);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_CMP, addr);
+            m_formatter.immediate32(imm);
+        }
+    }
+#endif
+
+    void cmpw_rm(RegisterID src, int offset, RegisterID base, RegisterID index, int scale)
+    {
+        m_formatter.prefix(PRE_OPERAND_SIZE);
+        m_formatter.oneByteOp(OP_CMP_EvGv, src, base, index, scale, offset);
+    }
+
+    void cmpw_im(int imm, int offset, RegisterID base, RegisterID index, int scale)
+    {
+        if (CAN_SIGN_EXTEND_8_32(imm)) {
+            m_formatter.prefix(PRE_OPERAND_SIZE);
+            m_formatter.oneByteOp(OP_GROUP1_EvIb, GROUP1_OP_CMP, base, index, scale, offset);
+            m_formatter.immediate8(imm);
+        } else {
+            m_formatter.prefix(PRE_OPERAND_SIZE);
+            m_formatter.oneByteOp(OP_GROUP1_EvIz, GROUP1_OP_CMP, base, index, scale, offset);
+            m_formatter.immediate16(imm);
+        }
+    }
+
+    void testl_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_TEST_EvGv, src, dst);
+    }
+    
+    void testl_i32r(int imm, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_GROUP3_EvIz, GROUP3_OP_TEST, dst);
+        m_formatter.immediate32(imm);
+    }
+
+    void testl_i32m(int imm, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_GROUP3_EvIz, GROUP3_OP_TEST, base, offset);
+        m_formatter.immediate32(imm);
+    }
+    
+    void testb_im(int imm, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_GROUP3_EbIb, GROUP3_OP_TEST, base, offset);
+        m_formatter.immediate8(imm);
+    }
+    
+    void testb_im(int imm, int offset, RegisterID base, RegisterID index, int scale)
+    {
+        m_formatter.oneByteOp(OP_GROUP3_EbIb, GROUP3_OP_TEST, base, index, scale, offset);
+        m_formatter.immediate8(imm);
+    }
+
+    void testl_i32m(int imm, int offset, RegisterID base, RegisterID index, int scale)
+    {
+        m_formatter.oneByteOp(OP_GROUP3_EvIz, GROUP3_OP_TEST, base, index, scale, offset);
+        m_formatter.immediate32(imm);
+    }
+
+#if CPU(X86_64)
+    void testq_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_TEST_EvGv, src, dst);
+    }
+
+    void testq_i32r(int imm, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_GROUP3_EvIz, GROUP3_OP_TEST, dst);
+        m_formatter.immediate32(imm);
+    }
+
+    void testq_i32m(int imm, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp64(OP_GROUP3_EvIz, GROUP3_OP_TEST, base, offset);
+        m_formatter.immediate32(imm);
+    }
+
+    void testq_i32m(int imm, int offset, RegisterID base, RegisterID index, int scale)
+    {
+        m_formatter.oneByteOp64(OP_GROUP3_EvIz, GROUP3_OP_TEST, base, index, scale, offset);
+        m_formatter.immediate32(imm);
+    }
+#endif 
+
+    void testw_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.prefix(PRE_OPERAND_SIZE);
+        m_formatter.oneByteOp(OP_TEST_EvGv, src, dst);
+    }
+    
+    void testb_i8r(int imm, RegisterID dst)
+    {
+        m_formatter.oneByteOp8(OP_GROUP3_EbIb, GROUP3_OP_TEST, dst);
+        m_formatter.immediate8(imm);
+    }
+
+    void setCC_r(Condition cond, RegisterID dst)
+    {
+        m_formatter.twoByteOp8(setccOpcode(cond), (GroupOpcodeID)0, dst);
+    }
+
+    void sete_r(RegisterID dst)
+    {
+        m_formatter.twoByteOp8(setccOpcode(ConditionE), (GroupOpcodeID)0, dst);
+    }
+
+    void setz_r(RegisterID dst)
+    {
+        sete_r(dst);
+    }
+
+    void setne_r(RegisterID dst)
+    {
+        m_formatter.twoByteOp8(setccOpcode(ConditionNE), (GroupOpcodeID)0, dst);
+    }
+
+    void setnz_r(RegisterID dst)
+    {
+        setne_r(dst);
+    }
+
+    // Various move ops:
+
+    void cdq()
+    {
+        m_formatter.oneByteOp(OP_CDQ);
+    }
+
+    void xchgl_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_XCHG_EvGv, src, dst);
+    }
+
+#if CPU(X86_64)
+    void xchgq_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_XCHG_EvGv, src, dst);
+    }
+#endif
+
+    void movl_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_MOV_EvGv, src, dst);
+    }
+    
+    void movl_rm(RegisterID src, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_MOV_EvGv, src, base, offset);
+    }
+
+    void movl_rm_disp32(RegisterID src, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp_disp32(OP_MOV_EvGv, src, base, offset);
+    }
+
+    void movl_rm(RegisterID src, int offset, RegisterID base, RegisterID index, int scale)
+    {
+        m_formatter.oneByteOp(OP_MOV_EvGv, src, base, index, scale, offset);
+    }
+    
+    void movl_mEAX(void* addr)
+    {
+        m_formatter.oneByteOp(OP_MOV_EAXOv);
+#if CPU(X86_64)
+        m_formatter.immediate64(reinterpret_cast<int64_t>(addr));
+#else
+        m_formatter.immediate32(reinterpret_cast<int>(addr));
+#endif
+    }
+
+    void movl_mr(int offset, RegisterID base, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_MOV_GvEv, dst, base, offset);
+    }
+
+    void movl_mr_disp32(int offset, RegisterID base, RegisterID dst)
+    {
+        m_formatter.oneByteOp_disp32(OP_MOV_GvEv, dst, base, offset);
+    }
+
+    void movl_mr(int offset, RegisterID base, RegisterID index, int scale, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_MOV_GvEv, dst, base, index, scale, offset);
+    }
+
+    void movl_i32r(int imm, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_MOV_EAXIv, dst);
+        m_formatter.immediate32(imm);
+    }
+
+    void movl_i32m(int imm, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_GROUP11_EvIz, GROUP11_MOV, base, offset);
+        m_formatter.immediate32(imm);
+    }
+
+    void movl_EAXm(void* addr)
+    {
+        m_formatter.oneByteOp(OP_MOV_OvEAX);
+#if CPU(X86_64)
+        m_formatter.immediate64(reinterpret_cast<int64_t>(addr));
+#else
+        m_formatter.immediate32(reinterpret_cast<int>(addr));
+#endif
+    }
+
+#if CPU(X86_64)
+    void movq_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_MOV_EvGv, src, dst);
+    }
+
+    void movq_rm(RegisterID src, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp64(OP_MOV_EvGv, src, base, offset);
+    }
+
+    void movq_rm_disp32(RegisterID src, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp64_disp32(OP_MOV_EvGv, src, base, offset);
+    }
+
+    void movq_rm(RegisterID src, int offset, RegisterID base, RegisterID index, int scale)
+    {
+        m_formatter.oneByteOp64(OP_MOV_EvGv, src, base, index, scale, offset);
+    }
+
+    void movq_mEAX(void* addr)
+    {
+        m_formatter.oneByteOp64(OP_MOV_EAXOv);
+        m_formatter.immediate64(reinterpret_cast<int64_t>(addr));
+    }
+
+    void movq_EAXm(void* addr)
+    {
+        m_formatter.oneByteOp64(OP_MOV_OvEAX);
+        m_formatter.immediate64(reinterpret_cast<int64_t>(addr));
+    }
+
+    void movq_mr(int offset, RegisterID base, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_MOV_GvEv, dst, base, offset);
+    }
+
+    void movq_mr_disp32(int offset, RegisterID base, RegisterID dst)
+    {
+        m_formatter.oneByteOp64_disp32(OP_MOV_GvEv, dst, base, offset);
+    }
+
+    void movq_mr(int offset, RegisterID base, RegisterID index, int scale, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_MOV_GvEv, dst, base, index, scale, offset);
+    }
+
+    void movq_i32m(int imm, int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp64(OP_GROUP11_EvIz, GROUP11_MOV, base, offset);
+        m_formatter.immediate32(imm);
+    }
+
+    void movq_i64r(int64_t imm, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_MOV_EAXIv, dst);
+        m_formatter.immediate64(imm);
+    }
+    
+    void movsxd_rr(RegisterID src, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_MOVSXD_GvEv, dst, src);
+    }
+    
+    
+#else
+    void movl_rm(RegisterID src, void* addr)
+    {
+        if (src == X86Registers::eax)
+            movl_EAXm(addr);
+        else 
+            m_formatter.oneByteOp(OP_MOV_EvGv, src, addr);
+    }
+    
+    void movl_mr(void* addr, RegisterID dst)
+    {
+        if (dst == X86Registers::eax)
+            movl_mEAX(addr);
+        else
+            m_formatter.oneByteOp(OP_MOV_GvEv, dst, addr);
+    }
+
+    void movl_i32m(int imm, void* addr)
+    {
+        m_formatter.oneByteOp(OP_GROUP11_EvIz, GROUP11_MOV, addr);
+        m_formatter.immediate32(imm);
+    }
+#endif
+
+    void movzwl_mr(int offset, RegisterID base, RegisterID dst)
+    {
+        m_formatter.twoByteOp(OP2_MOVZX_GvEw, dst, base, offset);
+    }
+
+    void movzwl_mr(int offset, RegisterID base, RegisterID index, int scale, RegisterID dst)
+    {
+        m_formatter.twoByteOp(OP2_MOVZX_GvEw, dst, base, index, scale, offset);
+    }
+
+    void movzbl_rr(RegisterID src, RegisterID dst)
+    {
+        // In 64-bit, this may cause an unnecessary REX to be planted (if the dst register
+        // is in the range ESP-EDI, and the src would not have required a REX).  Unneeded
+        // REX prefixes are defined to be silently ignored by the processor.
+        m_formatter.twoByteOp8(OP2_MOVZX_GvEb, dst, src);
+    }
+
+    void leal_mr(int offset, RegisterID base, RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_LEA, dst, base, offset);
+    }
+#if CPU(X86_64)
+    void leaq_mr(int offset, RegisterID base, RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_LEA, dst, base, offset);
+    }
+#endif
+
+    // Flow control:
+
+    JmpSrc call()
+    {
+        m_formatter.oneByteOp(OP_CALL_rel32);
+        return m_formatter.immediateRel32();
+    }
+    
+    JmpSrc call(RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_GROUP5_Ev, GROUP5_OP_CALLN, dst);
+        return JmpSrc(m_formatter.size());
+    }
+    
+    void call_m(int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_GROUP5_Ev, GROUP5_OP_CALLN, base, offset);
+    }
+
+    JmpSrc jmp()
+    {
+        m_formatter.oneByteOp(OP_JMP_rel32);
+        return m_formatter.immediateRel32();
+    }
+    
+    // Return a JmpSrc so we have a label to the jump, so we can use this
+    // To make a tail recursive call on x86-64.  The MacroAssembler
+    // really shouldn't wrap this as a Jump, since it can't be linked. :-/
+    JmpSrc jmp_r(RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_GROUP5_Ev, GROUP5_OP_JMPN, dst);
+        return JmpSrc(m_formatter.size());
+    }
+    
+    void jmp_m(int offset, RegisterID base)
+    {
+        m_formatter.oneByteOp(OP_GROUP5_Ev, GROUP5_OP_JMPN, base, offset);
+    }
+
+    JmpSrc jne()
+    {
+        m_formatter.twoByteOp(jccRel32(ConditionNE));
+        return m_formatter.immediateRel32();
+    }
+    
+    JmpSrc jnz()
+    {
+        return jne();
+    }
+
+    JmpSrc je()
+    {
+        m_formatter.twoByteOp(jccRel32(ConditionE));
+        return m_formatter.immediateRel32();
+    }
+    
+    JmpSrc jz()
+    {
+        return je();
+    }
+
+    JmpSrc jl()
+    {
+        m_formatter.twoByteOp(jccRel32(ConditionL));
+        return m_formatter.immediateRel32();
+    }
+    
+    JmpSrc jb()
+    {
+        m_formatter.twoByteOp(jccRel32(ConditionB));
+        return m_formatter.immediateRel32();
+    }
+    
+    JmpSrc jle()
+    {
+        m_formatter.twoByteOp(jccRel32(ConditionLE));
+        return m_formatter.immediateRel32();
+    }
+    
+    JmpSrc jbe()
+    {
+        m_formatter.twoByteOp(jccRel32(ConditionBE));
+        return m_formatter.immediateRel32();
+    }
+    
+    JmpSrc jge()
+    {
+        m_formatter.twoByteOp(jccRel32(ConditionGE));
+        return m_formatter.immediateRel32();
+    }
+
+    JmpSrc jg()
+    {
+        m_formatter.twoByteOp(jccRel32(ConditionG));
+        return m_formatter.immediateRel32();
+    }
+
+    JmpSrc ja()
+    {
+        m_formatter.twoByteOp(jccRel32(ConditionA));
+        return m_formatter.immediateRel32();
+    }
+    
+    JmpSrc jae()
+    {
+        m_formatter.twoByteOp(jccRel32(ConditionAE));
+        return m_formatter.immediateRel32();
+    }
+    
+    JmpSrc jo()
+    {
+        m_formatter.twoByteOp(jccRel32(ConditionO));
+        return m_formatter.immediateRel32();
+    }
+
+    JmpSrc jp()
+    {
+        m_formatter.twoByteOp(jccRel32(ConditionP));
+        return m_formatter.immediateRel32();
+    }
+    
+    JmpSrc js()
+    {
+        m_formatter.twoByteOp(jccRel32(ConditionS));
+        return m_formatter.immediateRel32();
+    }
+
+    JmpSrc jCC(Condition cond)
+    {
+        m_formatter.twoByteOp(jccRel32(cond));
+        return m_formatter.immediateRel32();
+    }
+
+    // SSE operations:
+
+    void addsd_rr(XMMRegisterID src, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_ADDSD_VsdWsd, (RegisterID)dst, (RegisterID)src);
+    }
+
+    void addsd_mr(int offset, RegisterID base, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_ADDSD_VsdWsd, (RegisterID)dst, base, offset);
+    }
+
+    void cvtsi2sd_rr(RegisterID src, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_CVTSI2SD_VsdEd, (RegisterID)dst, src);
+    }
+
+    void cvtsi2sd_mr(int offset, RegisterID base, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_CVTSI2SD_VsdEd, (RegisterID)dst, base, offset);
+    }
+
+#if !CPU(X86_64)
+    void cvtsi2sd_mr(void* address, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_CVTSI2SD_VsdEd, (RegisterID)dst, address);
+    }
+#endif
+
+    void cvttsd2si_rr(XMMRegisterID src, RegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_CVTTSD2SI_GdWsd, dst, (RegisterID)src);
+    }
+
+    void movd_rr(XMMRegisterID src, RegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_66);
+        m_formatter.twoByteOp(OP2_MOVD_EdVd, (RegisterID)src, dst);
+    }
+
+#if CPU(X86_64)
+    void movq_rr(XMMRegisterID src, RegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_66);
+        m_formatter.twoByteOp64(OP2_MOVD_EdVd, (RegisterID)src, dst);
+    }
+
+    void movq_rr(RegisterID src, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_66);
+        m_formatter.twoByteOp64(OP2_MOVD_VdEd, (RegisterID)dst, src);
+    }
+#endif
+
+    void movsd_rm(XMMRegisterID src, int offset, RegisterID base)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_MOVSD_WsdVsd, (RegisterID)src, base, offset);
+    }
+
+    void movsd_mr(int offset, RegisterID base, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_MOVSD_VsdWsd, (RegisterID)dst, base, offset);
+    }
+
+#if !CPU(X86_64)
+    void movsd_mr(const void* address, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_MOVSD_VsdWsd, (RegisterID)dst, address);
+    }
+#endif
+
+    void mulsd_rr(XMMRegisterID src, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_MULSD_VsdWsd, (RegisterID)dst, (RegisterID)src);
+    }
+
+    void mulsd_mr(int offset, RegisterID base, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_MULSD_VsdWsd, (RegisterID)dst, base, offset);
+    }
+
+    void pextrw_irr(int whichWord, XMMRegisterID src, RegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_66);
+        m_formatter.twoByteOp(OP2_PEXTRW_GdUdIb, (RegisterID)dst, (RegisterID)src);
+        m_formatter.immediate8(whichWord);
+    }
+
+    void subsd_rr(XMMRegisterID src, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_SUBSD_VsdWsd, (RegisterID)dst, (RegisterID)src);
+    }
+
+    void subsd_mr(int offset, RegisterID base, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_SUBSD_VsdWsd, (RegisterID)dst, base, offset);
+    }
+
+    void ucomisd_rr(XMMRegisterID src, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_66);
+        m_formatter.twoByteOp(OP2_UCOMISD_VsdWsd, (RegisterID)dst, (RegisterID)src);
+    }
+
+    void ucomisd_mr(int offset, RegisterID base, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_66);
+        m_formatter.twoByteOp(OP2_UCOMISD_VsdWsd, (RegisterID)dst, base, offset);
+    }
+
+    void divsd_rr(XMMRegisterID src, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_DIVSD_VsdWsd, (RegisterID)dst, (RegisterID)src);
+    }
+
+    void divsd_mr(int offset, RegisterID base, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_DIVSD_VsdWsd, (RegisterID)dst, base, offset);
+    }
+
+    void xorpd_rr(XMMRegisterID src, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_66);
+        m_formatter.twoByteOp(OP2_XORPD_VpdWpd, (RegisterID)dst, (RegisterID)src);
+    }
+
+    void sqrtsd_rr(XMMRegisterID src, XMMRegisterID dst)
+    {
+        m_formatter.prefix(PRE_SSE_F2);
+        m_formatter.twoByteOp(OP2_SQRTSD_VsdWsd, (RegisterID)dst, (RegisterID)src);
+    }
+
+    // Misc instructions:
+
+    void int3()
+    {
+        m_formatter.oneByteOp(OP_INT3);
+    }
+    
+    void ret()
+    {
+        m_formatter.oneByteOp(OP_RET);
+    }
+
+    void predictNotTaken()
+    {
+        m_formatter.prefix(PRE_PREDICT_BRANCH_NOT_TAKEN);
+    }
+
+    // Assembler admin methods:
+
+    JmpDst label()
+    {
+        return JmpDst(m_formatter.size());
+    }
+    
+    static JmpDst labelFor(JmpSrc jump, intptr_t offset = 0)
+    {
+        return JmpDst(jump.m_offset + offset);
+    }
+    
+    JmpDst align(int alignment)
+    {
+        while (!m_formatter.isAligned(alignment))
+            m_formatter.oneByteOp(OP_HLT);
+
+        return label();
+    }
+
+    // Linking & patching:
+    //
+    // 'link' and 'patch' methods are for use on unprotected code - such as the code
+    // within the AssemblerBuffer, and code being patched by the patch buffer.  Once
+    // code has been finalized it is (platform support permitting) within a non-
+    // writable region of memory; to modify the code in an execute-only execuable
+    // pool the 'repatch' and 'relink' methods should be used.
+
+    void linkJump(JmpSrc from, JmpDst to)
+    {
+        ASSERT(from.m_offset != -1);
+        ASSERT(to.m_offset != -1);
+
+        char* code = reinterpret_cast<char*>(m_formatter.data());
+        setRel32(code + from.m_offset, code + to.m_offset);
+    }
+    
+    static void linkJump(void* code, JmpSrc from, void* to)
+    {
+        ASSERT(from.m_offset != -1);
+
+        setRel32(reinterpret_cast<char*>(code) + from.m_offset, to);
+    }
+
+    static void linkCall(void* code, JmpSrc from, void* to)
+    {
+        ASSERT(from.m_offset != -1);
+
+        setRel32(reinterpret_cast<char*>(code) + from.m_offset, to);
+    }
+
+    static void linkPointer(void* code, JmpDst where, void* value)
+    {
+        ASSERT(where.m_offset != -1);
+
+        setPointer(reinterpret_cast<char*>(code) + where.m_offset, value);
+    }
+
+    static void relinkJump(void* from, void* to)
+    {
+        setRel32(from, to);
+    }
+    
+    static void relinkCall(void* from, void* to)
+    {
+        setRel32(from, to);
+    }
+
+    static void repatchInt32(void* where, int32_t value)
+    {
+        setInt32(where, value);
+    }
+
+    static void repatchPointer(void* where, void* value)
+    {
+        setPointer(where, value);
+    }
+
+    static void repatchLoadPtrToLEA(void* where)
+    {
+#if CPU(X86_64)
+        // On x86-64 pointer memory accesses require a 64-bit operand, and as such a REX prefix.
+        // Skip over the prefix byte.
+        where = reinterpret_cast<char*>(where) + 1;
+#endif
+        *reinterpret_cast<unsigned char*>(where) = static_cast<unsigned char>(OP_LEA);
+    }
+    
+    static unsigned getCallReturnOffset(JmpSrc call)
+    {
+        ASSERT(call.m_offset >= 0);
+        return call.m_offset;
+    }
+
+    static void* getRelocatedAddress(void* code, JmpSrc jump)
+    {
+        ASSERT(jump.m_offset != -1);
+
+        return reinterpret_cast<void*>(reinterpret_cast<ptrdiff_t>(code) + jump.m_offset);
+    }
+    
+    static void* getRelocatedAddress(void* code, JmpDst destination)
+    {
+        ASSERT(destination.m_offset != -1);
+
+        return reinterpret_cast<void*>(reinterpret_cast<ptrdiff_t>(code) + destination.m_offset);
+    }
+    
+    static int getDifferenceBetweenLabels(JmpDst src, JmpDst dst)
+    {
+        return dst.m_offset - src.m_offset;
+    }
+    
+    static int getDifferenceBetweenLabels(JmpDst src, JmpSrc dst)
+    {
+        return dst.m_offset - src.m_offset;
+    }
+    
+    static int getDifferenceBetweenLabels(JmpSrc src, JmpDst dst)
+    {
+        return dst.m_offset - src.m_offset;
+    }
+    
+    void* executableCopy(ExecutablePool* allocator)
+    {
+        void* copy = m_formatter.executableCopy(allocator);
+        ASSERT(copy);
+        return copy;
+    }
+
+private:
+
+    static void setPointer(void* where, void* value)
+    {
+        reinterpret_cast<void**>(where)[-1] = value;
+    }
+
+    static void setInt32(void* where, int32_t value)
+    {
+        reinterpret_cast<int32_t*>(where)[-1] = value;
+    }
+
+    static void setRel32(void* from, void* to)
+    {
+        intptr_t offset = reinterpret_cast<intptr_t>(to) - reinterpret_cast<intptr_t>(from);
+        ASSERT(offset == static_cast<int32_t>(offset));
+
+        setInt32(from, offset);
+    }
+
+    class X86InstructionFormatter {
+
+        static const int maxInstructionSize = 16;
+
+    public:
+
+        // Legacy prefix bytes:
+        //
+        // These are emmitted prior to the instruction.
+
+        void prefix(OneByteOpcodeID pre)
+        {
+            m_buffer.putByte(pre);
+        }
+
+        // Word-sized operands / no operand instruction formatters.
+        //
+        // In addition to the opcode, the following operand permutations are supported:
+        //   * None - instruction takes no operands.
+        //   * One register - the low three bits of the RegisterID are added into the opcode.
+        //   * Two registers - encode a register form ModRm (for all ModRm formats, the reg field is passed first, and a GroupOpcodeID may be passed in its place).
+        //   * Three argument ModRM - a register, and a register and an offset describing a memory operand.
+        //   * Five argument ModRM - a register, and a base register, an index, scale, and offset describing a memory operand.
+        //
+        // For 32-bit x86 targets, the address operand may also be provided as a void*.
+        // On 64-bit targets REX prefixes will be planted as necessary, where high numbered registers are used.
+        //
+        // The twoByteOp methods plant two-byte Intel instructions sequences (first opcode byte 0x0F).
+
+        void oneByteOp(OneByteOpcodeID opcode)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            m_buffer.putByteUnchecked(opcode);
+        }
+
+        void oneByteOp(OneByteOpcodeID opcode, RegisterID reg)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexIfNeeded(0, 0, reg);
+            m_buffer.putByteUnchecked(opcode + (reg & 7));
+        }
+
+        void oneByteOp(OneByteOpcodeID opcode, int reg, RegisterID rm)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexIfNeeded(reg, 0, rm);
+            m_buffer.putByteUnchecked(opcode);
+            registerModRM(reg, rm);
+        }
+
+        void oneByteOp(OneByteOpcodeID opcode, int reg, RegisterID base, int offset)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexIfNeeded(reg, 0, base);
+            m_buffer.putByteUnchecked(opcode);
+            memoryModRM(reg, base, offset);
+        }
+
+        void oneByteOp_disp32(OneByteOpcodeID opcode, int reg, RegisterID base, int offset)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexIfNeeded(reg, 0, base);
+            m_buffer.putByteUnchecked(opcode);
+            memoryModRM_disp32(reg, base, offset);
+        }
+
+        void oneByteOp(OneByteOpcodeID opcode, int reg, RegisterID base, RegisterID index, int scale, int offset)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexIfNeeded(reg, index, base);
+            m_buffer.putByteUnchecked(opcode);
+            memoryModRM(reg, base, index, scale, offset);
+        }
+
+#if !CPU(X86_64)
+        void oneByteOp(OneByteOpcodeID opcode, int reg, void* address)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            m_buffer.putByteUnchecked(opcode);
+            memoryModRM(reg, address);
+        }
+#endif
+
+        void twoByteOp(TwoByteOpcodeID opcode)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            m_buffer.putByteUnchecked(OP_2BYTE_ESCAPE);
+            m_buffer.putByteUnchecked(opcode);
+        }
+
+        void twoByteOp(TwoByteOpcodeID opcode, int reg, RegisterID rm)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexIfNeeded(reg, 0, rm);
+            m_buffer.putByteUnchecked(OP_2BYTE_ESCAPE);
+            m_buffer.putByteUnchecked(opcode);
+            registerModRM(reg, rm);
+        }
+
+        void twoByteOp(TwoByteOpcodeID opcode, int reg, RegisterID base, int offset)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexIfNeeded(reg, 0, base);
+            m_buffer.putByteUnchecked(OP_2BYTE_ESCAPE);
+            m_buffer.putByteUnchecked(opcode);
+            memoryModRM(reg, base, offset);
+        }
+
+        void twoByteOp(TwoByteOpcodeID opcode, int reg, RegisterID base, RegisterID index, int scale, int offset)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexIfNeeded(reg, index, base);
+            m_buffer.putByteUnchecked(OP_2BYTE_ESCAPE);
+            m_buffer.putByteUnchecked(opcode);
+            memoryModRM(reg, base, index, scale, offset);
+        }
+
+#if !CPU(X86_64)
+        void twoByteOp(TwoByteOpcodeID opcode, int reg, const void* address)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            m_buffer.putByteUnchecked(OP_2BYTE_ESCAPE);
+            m_buffer.putByteUnchecked(opcode);
+            memoryModRM(reg, address);
+        }
+#endif
+
+#if CPU(X86_64)
+        // Quad-word-sized operands:
+        //
+        // Used to format 64-bit operantions, planting a REX.w prefix.
+        // When planting d64 or f64 instructions, not requiring a REX.w prefix,
+        // the normal (non-'64'-postfixed) formatters should be used.
+
+        void oneByteOp64(OneByteOpcodeID opcode)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexW(0, 0, 0);
+            m_buffer.putByteUnchecked(opcode);
+        }
+
+        void oneByteOp64(OneByteOpcodeID opcode, RegisterID reg)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexW(0, 0, reg);
+            m_buffer.putByteUnchecked(opcode + (reg & 7));
+        }
+
+        void oneByteOp64(OneByteOpcodeID opcode, int reg, RegisterID rm)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexW(reg, 0, rm);
+            m_buffer.putByteUnchecked(opcode);
+            registerModRM(reg, rm);
+        }
+
+        void oneByteOp64(OneByteOpcodeID opcode, int reg, RegisterID base, int offset)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexW(reg, 0, base);
+            m_buffer.putByteUnchecked(opcode);
+            memoryModRM(reg, base, offset);
+        }
+
+        void oneByteOp64_disp32(OneByteOpcodeID opcode, int reg, RegisterID base, int offset)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexW(reg, 0, base);
+            m_buffer.putByteUnchecked(opcode);
+            memoryModRM_disp32(reg, base, offset);
+        }
+
+        void oneByteOp64(OneByteOpcodeID opcode, int reg, RegisterID base, RegisterID index, int scale, int offset)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexW(reg, index, base);
+            m_buffer.putByteUnchecked(opcode);
+            memoryModRM(reg, base, index, scale, offset);
+        }
+
+        void twoByteOp64(TwoByteOpcodeID opcode, int reg, RegisterID rm)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexW(reg, 0, rm);
+            m_buffer.putByteUnchecked(OP_2BYTE_ESCAPE);
+            m_buffer.putByteUnchecked(opcode);
+            registerModRM(reg, rm);
+        }
+#endif
+
+        // Byte-operands:
+        //
+        // These methods format byte operations.  Byte operations differ from the normal
+        // formatters in the circumstances under which they will decide to emit REX prefixes.
+        // These should be used where any register operand signifies a byte register.
+        //
+        // The disctinction is due to the handling of register numbers in the range 4..7 on
+        // x86-64.  These register numbers may either represent the second byte of the first
+        // four registers (ah..bh) or the first byte of the second four registers (spl..dil).
+        //
+        // Since ah..bh cannot be used in all permutations of operands (specifically cannot
+        // be accessed where a REX prefix is present), these are likely best treated as
+        // deprecated.  In order to ensure the correct registers spl..dil are selected a
+        // REX prefix will be emitted for any byte register operand in the range 4..15.
+        //
+        // These formatters may be used in instructions where a mix of operand sizes, in which
+        // case an unnecessary REX will be emitted, for example:
+        //     movzbl %al, %edi
+        // In this case a REX will be planted since edi is 7 (and were this a byte operand
+        // a REX would be required to specify dil instead of bh).  Unneeded REX prefixes will
+        // be silently ignored by the processor.
+        //
+        // Address operands should still be checked using regRequiresRex(), while byteRegRequiresRex()
+        // is provided to check byte register operands.
+
+        void oneByteOp8(OneByteOpcodeID opcode, GroupOpcodeID groupOp, RegisterID rm)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexIf(byteRegRequiresRex(rm), 0, 0, rm);
+            m_buffer.putByteUnchecked(opcode);
+            registerModRM(groupOp, rm);
+        }
+
+        void twoByteOp8(TwoByteOpcodeID opcode, RegisterID reg, RegisterID rm)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexIf(byteRegRequiresRex(reg)|byteRegRequiresRex(rm), reg, 0, rm);
+            m_buffer.putByteUnchecked(OP_2BYTE_ESCAPE);
+            m_buffer.putByteUnchecked(opcode);
+            registerModRM(reg, rm);
+        }
+
+        void twoByteOp8(TwoByteOpcodeID opcode, GroupOpcodeID groupOp, RegisterID rm)
+        {
+            m_buffer.ensureSpace(maxInstructionSize);
+            emitRexIf(byteRegRequiresRex(rm), 0, 0, rm);
+            m_buffer.putByteUnchecked(OP_2BYTE_ESCAPE);
+            m_buffer.putByteUnchecked(opcode);
+            registerModRM(groupOp, rm);
+        }
+
+        // Immediates:
+        //
+        // An immedaite should be appended where appropriate after an op has been emitted.
+        // The writes are unchecked since the opcode formatters above will have ensured space.
+
+        void immediate8(int imm)
+        {
+            m_buffer.putByteUnchecked(imm);
+        }
+
+        void immediate16(int imm)
+        {
+            m_buffer.putShortUnchecked(imm);
+        }
+
+        void immediate32(int imm)
+        {
+            m_buffer.putIntUnchecked(imm);
+        }
+
+        void immediate64(int64_t imm)
+        {
+            m_buffer.putInt64Unchecked(imm);
+        }
+
+        JmpSrc immediateRel32()
+        {
+            m_buffer.putIntUnchecked(0);
+            return JmpSrc(m_buffer.size());
+        }
+
+        // Administrative methods:
+
+        size_t size() const { return m_buffer.size(); }
+        bool isAligned(int alignment) const { return m_buffer.isAligned(alignment); }
+        void* data() const { return m_buffer.data(); }
+        void* executableCopy(ExecutablePool* allocator) { return m_buffer.executableCopy(allocator); }
+
+    private:
+
+        // Internals; ModRm and REX formatters.
+
+        static const RegisterID noBase = X86Registers::ebp;
+        static const RegisterID hasSib = X86Registers::esp;
+        static const RegisterID noIndex = X86Registers::esp;
+#if CPU(X86_64)
+        static const RegisterID noBase2 = X86Registers::r13;
+        static const RegisterID hasSib2 = X86Registers::r12;
+
+        // Registers r8 & above require a REX prefixe.
+        inline bool regRequiresRex(int reg)
+        {
+            return (reg >= X86Registers::r8);
+        }
+
+        // Byte operand register spl & above require a REX prefix (to prevent the 'H' registers be accessed).
+        inline bool byteRegRequiresRex(int reg)
+        {
+            return (reg >= X86Registers::esp);
+        }
+
+        // Format a REX prefix byte.
+        inline void emitRex(bool w, int r, int x, int b)
+        {
+            m_buffer.putByteUnchecked(PRE_REX | ((int)w << 3) | ((r>>3)<<2) | ((x>>3)<<1) | (b>>3));
+        }
+
+        // Used to plant a REX byte with REX.w set (for 64-bit operations).
+        inline void emitRexW(int r, int x, int b)
+        {
+            emitRex(true, r, x, b);
+        }
+
+        // Used for operations with byte operands - use byteRegRequiresRex() to check register operands,
+        // regRequiresRex() to check other registers (i.e. address base & index).
+        inline void emitRexIf(bool condition, int r, int x, int b)
+        {
+            if (condition) emitRex(false, r, x, b);
+        }
+
+        // Used for word sized operations, will plant a REX prefix if necessary (if any register is r8 or above).
+        inline void emitRexIfNeeded(int r, int x, int b)
+        {
+            emitRexIf(regRequiresRex(r) || regRequiresRex(x) || regRequiresRex(b), r, x, b);
+        }
+#else
+        // No REX prefix bytes on 32-bit x86.
+        inline bool regRequiresRex(int) { return false; }
+        inline bool byteRegRequiresRex(int) { return false; }
+        inline void emitRexIf(bool, int, int, int) {}
+        inline void emitRexIfNeeded(int, int, int) {}
+#endif
+
+        enum ModRmMode {
+            ModRmMemoryNoDisp,
+            ModRmMemoryDisp8,
+            ModRmMemoryDisp32,
+            ModRmRegister,
+        };
+
+        void putModRm(ModRmMode mode, int reg, RegisterID rm)
+        {
+            m_buffer.putByteUnchecked((mode << 6) | ((reg & 7) << 3) | (rm & 7));
+        }
+
+        void putModRmSib(ModRmMode mode, int reg, RegisterID base, RegisterID index, int scale)
+        {
+            ASSERT(mode != ModRmRegister);
+
+            putModRm(mode, reg, hasSib);
+            m_buffer.putByteUnchecked((scale << 6) | ((index & 7) << 3) | (base & 7));
+        }
+
+        void registerModRM(int reg, RegisterID rm)
+        {
+            putModRm(ModRmRegister, reg, rm);
+        }
+
+        void memoryModRM(int reg, RegisterID base, int offset)
+        {
+            // A base of esp or r12 would be interpreted as a sib, so force a sib with no index & put the base in there.
+#if CPU(X86_64)
+            if ((base == hasSib) || (base == hasSib2)) {
+#else
+            if (base == hasSib) {
+#endif
+                if (!offset) // No need to check if the base is noBase, since we know it is hasSib!
+                    putModRmSib(ModRmMemoryNoDisp, reg, base, noIndex, 0);
+                else if (CAN_SIGN_EXTEND_8_32(offset)) {
+                    putModRmSib(ModRmMemoryDisp8, reg, base, noIndex, 0);
+                    m_buffer.putByteUnchecked(offset);
+                } else {
+                    putModRmSib(ModRmMemoryDisp32, reg, base, noIndex, 0);
+                    m_buffer.putIntUnchecked(offset);
+                }
+            } else {
+#if CPU(X86_64)
+                if (!offset && (base != noBase) && (base != noBase2))
+#else
+                if (!offset && (base != noBase))
+#endif
+                    putModRm(ModRmMemoryNoDisp, reg, base);
+                else if (CAN_SIGN_EXTEND_8_32(offset)) {
+                    putModRm(ModRmMemoryDisp8, reg, base);
+                    m_buffer.putByteUnchecked(offset);
+                } else {
+                    putModRm(ModRmMemoryDisp32, reg, base);
+                    m_buffer.putIntUnchecked(offset);
+                }
+            }
+        }
+    
+        void memoryModRM_disp32(int reg, RegisterID base, int offset)
+        {
+            // A base of esp or r12 would be interpreted as a sib, so force a sib with no index & put the base in there.
+#if CPU(X86_64)
+            if ((base == hasSib) || (base == hasSib2)) {
+#else
+            if (base == hasSib) {
+#endif
+                putModRmSib(ModRmMemoryDisp32, reg, base, noIndex, 0);
+                m_buffer.putIntUnchecked(offset);
+            } else {
+                putModRm(ModRmMemoryDisp32, reg, base);
+                m_buffer.putIntUnchecked(offset);
+            }
+        }
+    
+        void memoryModRM(int reg, RegisterID base, RegisterID index, int scale, int offset)
+        {
+            ASSERT(index != noIndex);
+
+#if CPU(X86_64)
+            if (!offset && (base != noBase) && (base != noBase2))
+#else
+            if (!offset && (base != noBase))
+#endif
+                putModRmSib(ModRmMemoryNoDisp, reg, base, index, scale);
+            else if (CAN_SIGN_EXTEND_8_32(offset)) {
+                putModRmSib(ModRmMemoryDisp8, reg, base, index, scale);
+                m_buffer.putByteUnchecked(offset);
+            } else {
+                putModRmSib(ModRmMemoryDisp32, reg, base, index, scale);
+                m_buffer.putIntUnchecked(offset);
+            }
+        }
+
+#if !CPU(X86_64)
+        void memoryModRM(int reg, const void* address)
+        {
+            // noBase + ModRmMemoryNoDisp means noBase + ModRmMemoryDisp32!
+            putModRm(ModRmMemoryNoDisp, reg, noBase);
+            m_buffer.putIntUnchecked(reinterpret_cast<int32_t>(address));
+        }
+#endif
+
+        AssemblerBuffer m_buffer;
+    } m_formatter;
+};
+
+} // namespace JSC
+
+#endif // ENABLE(ASSEMBLER) && CPU(X86)
+
+#endif // X86Assembler_h