JavaScriptCore/assembler/ARMv7Assembler.h
changeset 0 4f2f89ce4247
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/JavaScriptCore/assembler/ARMv7Assembler.h	Fri Sep 17 09:02:29 2010 +0300
@@ -0,0 +1,2044 @@
+/*
+ * Copyright (C) 2009 Apple Inc. All rights reserved.
+ * Copyright (C) 2010 University of Szeged
+ *
+ * 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 ARMAssembler_h
+#define ARMAssembler_h
+
+#if ENABLE(ASSEMBLER) && CPU(ARM_THUMB2)
+
+#include "AssemblerBuffer.h"
+#include <wtf/Assertions.h>
+#include <wtf/Vector.h>
+#include <stdint.h>
+
+namespace JSC {
+
+namespace ARMRegisters {
+    typedef enum {
+        r0,
+        r1,
+        r2,
+        r3,
+        r4,
+        r5,
+        r6,
+        r7, wr = r7,   // thumb work register
+        r8,
+        r9, sb = r9,   // static base
+        r10, sl = r10, // stack limit
+        r11, fp = r11, // frame pointer
+        r12, ip = r12,
+        r13, sp = r13,
+        r14, lr = r14,
+        r15, pc = r15,
+    } RegisterID;
+
+    typedef enum {
+        s0,
+        s1,
+        s2,
+        s3,
+        s4,
+        s5,
+        s6,
+        s7,
+        s8,
+        s9,
+        s10,
+        s11,
+        s12,
+        s13,
+        s14,
+        s15,
+        s16,
+        s17,
+        s18,
+        s19,
+        s20,
+        s21,
+        s22,
+        s23,
+        s24,
+        s25,
+        s26,
+        s27,
+        s28,
+        s29,
+        s30,
+        s31,
+    } FPSingleRegisterID;
+
+    typedef enum {
+        d0,
+        d1,
+        d2,
+        d3,
+        d4,
+        d5,
+        d6,
+        d7,
+        d8,
+        d9,
+        d10,
+        d11,
+        d12,
+        d13,
+        d14,
+        d15,
+        d16,
+        d17,
+        d18,
+        d19,
+        d20,
+        d21,
+        d22,
+        d23,
+        d24,
+        d25,
+        d26,
+        d27,
+        d28,
+        d29,
+        d30,
+        d31,
+    } FPDoubleRegisterID;
+
+    typedef enum {
+        q0,
+        q1,
+        q2,
+        q3,
+        q4,
+        q5,
+        q6,
+        q7,
+        q8,
+        q9,
+        q10,
+        q11,
+        q12,
+        q13,
+        q14,
+        q15,
+        q16,
+        q17,
+        q18,
+        q19,
+        q20,
+        q21,
+        q22,
+        q23,
+        q24,
+        q25,
+        q26,
+        q27,
+        q28,
+        q29,
+        q30,
+        q31,
+    } FPQuadRegisterID;
+
+    inline FPSingleRegisterID asSingle(FPDoubleRegisterID reg)
+    {
+        ASSERT(reg < d16);
+        return (FPSingleRegisterID)(reg << 1);
+    }
+
+    inline FPDoubleRegisterID asDouble(FPSingleRegisterID reg)
+    {
+        ASSERT(!(reg & 1));
+        return (FPDoubleRegisterID)(reg >> 1);
+    }
+}
+
+class ARMv7Assembler;
+class ARMThumbImmediate {
+    friend class ARMv7Assembler;
+
+    typedef uint8_t ThumbImmediateType;
+    static const ThumbImmediateType TypeInvalid = 0;
+    static const ThumbImmediateType TypeEncoded = 1;
+    static const ThumbImmediateType TypeUInt16 = 2;
+
+    typedef union {
+        int16_t asInt;
+        struct {
+            unsigned imm8 : 8;
+            unsigned imm3 : 3;
+            unsigned i    : 1;
+            unsigned imm4 : 4;
+        };
+        // If this is an encoded immediate, then it may describe a shift, or a pattern.
+        struct {
+            unsigned shiftValue7 : 7;
+            unsigned shiftAmount : 5;
+        };
+        struct {
+            unsigned immediate   : 8;
+            unsigned pattern     : 4;
+        };
+    } ThumbImmediateValue;
+
+    // byte0 contains least significant bit; not using an array to make client code endian agnostic.
+    typedef union {
+        int32_t asInt;
+        struct {
+            uint8_t byte0;
+            uint8_t byte1;
+            uint8_t byte2;
+            uint8_t byte3;
+        };
+    } PatternBytes;
+
+    ALWAYS_INLINE static void countLeadingZerosPartial(uint32_t& value, int32_t& zeros, const int N)
+    {
+        if (value & ~((1 << N) - 1)) /* check for any of the top N bits (of 2N bits) are set */
+            value >>= N;             /* if any were set, lose the bottom N */
+        else                         /* if none of the top N bits are set, */
+            zeros += N;              /* then we have identified N leading zeros */
+    }
+
+    static int32_t countLeadingZeros(uint32_t value)
+    {
+        if (!value)
+            return 32;
+
+        int32_t zeros = 0;
+        countLeadingZerosPartial(value, zeros, 16);
+        countLeadingZerosPartial(value, zeros, 8);
+        countLeadingZerosPartial(value, zeros, 4);
+        countLeadingZerosPartial(value, zeros, 2);
+        countLeadingZerosPartial(value, zeros, 1);
+        return zeros;
+    }
+
+    ARMThumbImmediate()
+        : m_type(TypeInvalid)
+    {
+        m_value.asInt = 0;
+    }
+        
+    ARMThumbImmediate(ThumbImmediateType type, ThumbImmediateValue value)
+        : m_type(type)
+        , m_value(value)
+    {
+    }
+
+    ARMThumbImmediate(ThumbImmediateType type, uint16_t value)
+        : m_type(TypeUInt16)
+    {
+        // Make sure this constructor is only reached with type TypeUInt16;
+        // this extra parameter makes the code a little clearer by making it
+        // explicit at call sites which type is being constructed
+        ASSERT_UNUSED(type, type == TypeUInt16);
+
+        m_value.asInt = value;
+    }
+
+public:
+    static ARMThumbImmediate makeEncodedImm(uint32_t value)
+    {
+        ThumbImmediateValue encoding;
+        encoding.asInt = 0;
+
+        // okay, these are easy.
+        if (value < 256) {
+            encoding.immediate = value;
+            encoding.pattern = 0;
+            return ARMThumbImmediate(TypeEncoded, encoding);
+        }
+
+        int32_t leadingZeros = countLeadingZeros(value);
+        // if there were 24 or more leading zeros, then we'd have hit the (value < 256) case.
+        ASSERT(leadingZeros < 24);
+
+        // Given a number with bit fields Z:B:C, where count(Z)+count(B)+count(C) == 32,
+        // Z are the bits known zero, B is the 8-bit immediate, C are the bits to check for
+        // zero.  count(B) == 8, so the count of bits to be checked is 24 - count(Z).
+        int32_t rightShiftAmount = 24 - leadingZeros;
+        if (value == ((value >> rightShiftAmount) << rightShiftAmount)) {
+            // Shift the value down to the low byte position.  The assign to 
+            // shiftValue7 drops the implicit top bit.
+            encoding.shiftValue7 = value >> rightShiftAmount;
+            // The endoded shift amount is the magnitude of a right rotate.
+            encoding.shiftAmount = 8 + leadingZeros;
+            return ARMThumbImmediate(TypeEncoded, encoding);
+        }
+        
+        PatternBytes bytes;
+        bytes.asInt = value;
+
+        if ((bytes.byte0 == bytes.byte1) && (bytes.byte0 == bytes.byte2) && (bytes.byte0 == bytes.byte3)) {
+            encoding.immediate = bytes.byte0;
+            encoding.pattern = 3;
+            return ARMThumbImmediate(TypeEncoded, encoding);
+        }
+
+        if ((bytes.byte0 == bytes.byte2) && !(bytes.byte1 | bytes.byte3)) {
+            encoding.immediate = bytes.byte0;
+            encoding.pattern = 1;
+            return ARMThumbImmediate(TypeEncoded, encoding);
+        }
+
+        if ((bytes.byte1 == bytes.byte3) && !(bytes.byte0 | bytes.byte2)) {
+            encoding.immediate = bytes.byte0;
+            encoding.pattern = 2;
+            return ARMThumbImmediate(TypeEncoded, encoding);
+        }
+
+        return ARMThumbImmediate();
+    }
+
+    static ARMThumbImmediate makeUInt12(int32_t value)
+    {
+        return (!(value & 0xfffff000))
+            ? ARMThumbImmediate(TypeUInt16, (uint16_t)value)
+            : ARMThumbImmediate();
+    }
+
+    static ARMThumbImmediate makeUInt12OrEncodedImm(int32_t value)
+    {
+        // If this is not a 12-bit unsigned it, try making an encoded immediate.
+        return (!(value & 0xfffff000))
+            ? ARMThumbImmediate(TypeUInt16, (uint16_t)value)
+            : makeEncodedImm(value);
+    }
+
+    // The 'make' methods, above, return a !isValid() value if the argument
+    // cannot be represented as the requested type.  This methods  is called
+    // 'get' since the argument can always be represented.
+    static ARMThumbImmediate makeUInt16(uint16_t value)
+    {
+        return ARMThumbImmediate(TypeUInt16, value);
+    }
+    
+    bool isValid()
+    {
+        return m_type != TypeInvalid;
+    }
+
+    // These methods rely on the format of encoded byte values.
+    bool isUInt3() { return !(m_value.asInt & 0xfff8); }
+    bool isUInt4() { return !(m_value.asInt & 0xfff0); }
+    bool isUInt5() { return !(m_value.asInt & 0xffe0); }
+    bool isUInt6() { return !(m_value.asInt & 0xffc0); }
+    bool isUInt7() { return !(m_value.asInt & 0xff80); }
+    bool isUInt8() { return !(m_value.asInt & 0xff00); }
+    bool isUInt9() { return (m_type == TypeUInt16) && !(m_value.asInt & 0xfe00); }
+    bool isUInt10() { return (m_type == TypeUInt16) && !(m_value.asInt & 0xfc00); }
+    bool isUInt12() { return (m_type == TypeUInt16) && !(m_value.asInt & 0xf000); }
+    bool isUInt16() { return m_type == TypeUInt16; }
+    uint8_t getUInt3() { ASSERT(isUInt3()); return m_value.asInt; }
+    uint8_t getUInt4() { ASSERT(isUInt4()); return m_value.asInt; }
+    uint8_t getUInt5() { ASSERT(isUInt5()); return m_value.asInt; }
+    uint8_t getUInt6() { ASSERT(isUInt6()); return m_value.asInt; }
+    uint8_t getUInt7() { ASSERT(isUInt7()); return m_value.asInt; }
+    uint8_t getUInt8() { ASSERT(isUInt8()); return m_value.asInt; }
+    uint8_t getUInt9() { ASSERT(isUInt9()); return m_value.asInt; }
+    uint8_t getUInt10() { ASSERT(isUInt10()); return m_value.asInt; }
+    uint16_t getUInt12() { ASSERT(isUInt12()); return m_value.asInt; }
+    uint16_t getUInt16() { ASSERT(isUInt16()); return m_value.asInt; }
+
+    bool isEncodedImm() { return m_type == TypeEncoded; }
+
+private:
+    ThumbImmediateType m_type;
+    ThumbImmediateValue m_value;
+};
+
+class VFPImmediate {
+public:
+    VFPImmediate(double d)
+        : m_value(-1)
+    {
+        union {
+            uint64_t i;
+            double d;
+        } u;
+
+        u.d = d;
+
+        int sign = (u.i >> 63);
+        int exponent = (u.i >> 52) & 0x7ff;
+        uint64_t mantissa = u.i & 0x000fffffffffffffull;
+
+        if ((exponent >= 0x3fc) && (exponent <= 0x403) && !(mantissa & 0x0000ffffffffffffull))
+            m_value = (sign << 7) | ((exponent & 7) << 4) | (int)(mantissa >> 48);
+    }
+
+    bool isValid()
+    {
+        return m_value != -1;
+    }
+    
+    uint8_t value()
+    {
+        return (uint8_t)m_value;
+    }
+
+private:
+    int m_value;
+};
+
+typedef enum {
+    SRType_LSL,
+    SRType_LSR,
+    SRType_ASR,
+    SRType_ROR,
+
+    SRType_RRX = SRType_ROR
+} ARMShiftType;
+
+class ARMv7Assembler;
+class ShiftTypeAndAmount {
+    friend class ARMv7Assembler;
+
+public:
+    ShiftTypeAndAmount()
+    {
+        m_u.type = (ARMShiftType)0;
+        m_u.amount = 0;
+    }
+    
+    ShiftTypeAndAmount(ARMShiftType type, unsigned amount)
+    {
+        m_u.type = type;
+        m_u.amount = amount & 31;
+    }
+    
+    unsigned lo4() { return m_u.lo4; }
+    unsigned hi4() { return m_u.hi4; }
+    
+private:
+    union {
+        struct {
+            unsigned lo4 : 4;
+            unsigned hi4 : 4;
+        };
+        struct {
+            unsigned type   : 2;
+            unsigned amount : 5;
+        };
+    } m_u;
+};
+
+
+class ARMv7Assembler {
+public:
+    ~ARMv7Assembler()
+    {
+        ASSERT(m_jumpsToLink.isEmpty());
+    }
+
+    typedef ARMRegisters::RegisterID RegisterID;
+    typedef ARMRegisters::FPSingleRegisterID FPSingleRegisterID;
+    typedef ARMRegisters::FPDoubleRegisterID FPDoubleRegisterID;
+    typedef ARMRegisters::FPQuadRegisterID FPQuadRegisterID;
+
+    // (HS, LO, HI, LS) -> (AE, B, A, BE)
+    // (VS, VC) -> (O, NO)
+    typedef enum {
+        ConditionEQ,
+        ConditionNE,
+        ConditionHS,
+        ConditionLO,
+        ConditionMI,
+        ConditionPL,
+        ConditionVS,
+        ConditionVC,
+        ConditionHI,
+        ConditionLS,
+        ConditionGE,
+        ConditionLT,
+        ConditionGT,
+        ConditionLE,
+        ConditionAL,
+
+        ConditionCS = ConditionHS,
+        ConditionCC = ConditionLO,
+    } Condition;
+
+    class JmpSrc {
+        friend class ARMv7Assembler;
+        friend class ARMInstructionFormatter;
+    public:
+        JmpSrc()
+            : m_offset(-1)
+        {
+        }
+
+    private:
+        JmpSrc(int offset)
+            : m_offset(offset)
+        {
+        }
+
+        int m_offset;
+    };
+    
+    class JmpDst {
+        friend class ARMv7Assembler;
+        friend class ARMInstructionFormatter;
+    public:
+        JmpDst()
+            : m_offset(-1)
+            , m_used(false)
+        {
+        }
+
+        bool isUsed() const { return m_used; }
+        void used() { m_used = true; }
+    private:
+        JmpDst(int offset)
+            : m_offset(offset)
+            , m_used(false)
+        {
+            ASSERT(m_offset == offset);
+        }
+
+        int m_offset : 31;
+        int m_used : 1;
+    };
+
+private:
+
+    struct LinkRecord {
+        LinkRecord(intptr_t from, intptr_t to)
+            : from(from)
+            , to(to)
+        {
+        }
+
+        intptr_t from;
+        intptr_t to;
+    };
+
+    // ARMv7, Appx-A.6.3
+    bool BadReg(RegisterID reg)
+    {
+        return (reg == ARMRegisters::sp) || (reg == ARMRegisters::pc);
+    }
+
+    uint32_t singleRegisterMask(FPSingleRegisterID rdNum, int highBitsShift, int lowBitShift)
+    {
+        uint32_t rdMask = (rdNum >> 1) << highBitsShift;
+        if (rdNum & 1)
+            rdMask |= 1 << lowBitShift;
+        return rdMask;
+    }
+
+    uint32_t doubleRegisterMask(FPDoubleRegisterID rdNum, int highBitShift, int lowBitsShift)
+    {
+        uint32_t rdMask = (rdNum & 0xf) << lowBitsShift;
+        if (rdNum & 16)
+            rdMask |= 1 << highBitShift;
+        return rdMask;
+    }
+
+    typedef enum {
+        OP_ADD_reg_T1       = 0x1800,
+        OP_SUB_reg_T1       = 0x1A00,
+        OP_ADD_imm_T1       = 0x1C00,
+        OP_SUB_imm_T1       = 0x1E00,
+        OP_MOV_imm_T1       = 0x2000,
+        OP_CMP_imm_T1       = 0x2800,
+        OP_ADD_imm_T2       = 0x3000,
+        OP_SUB_imm_T2       = 0x3800,
+        OP_AND_reg_T1       = 0x4000,
+        OP_EOR_reg_T1       = 0x4040,
+        OP_TST_reg_T1       = 0x4200,
+        OP_RSB_imm_T1       = 0x4240,
+        OP_CMP_reg_T1       = 0x4280,
+        OP_ORR_reg_T1       = 0x4300,
+        OP_MVN_reg_T1       = 0x43C0,
+        OP_ADD_reg_T2       = 0x4400,
+        OP_MOV_reg_T1       = 0x4600,
+        OP_BLX              = 0x4700,
+        OP_BX               = 0x4700,
+        OP_STR_reg_T1       = 0x5000,
+        OP_LDR_reg_T1       = 0x5800,
+        OP_LDRH_reg_T1      = 0x5A00,
+        OP_LDRB_reg_T1      = 0x5C00,
+        OP_STR_imm_T1       = 0x6000,
+        OP_LDR_imm_T1       = 0x6800,
+        OP_LDRB_imm_T1      = 0x7800,
+        OP_LDRH_imm_T1      = 0x8800,
+        OP_STR_imm_T2       = 0x9000,
+        OP_LDR_imm_T2       = 0x9800,
+        OP_ADD_SP_imm_T1    = 0xA800,
+        OP_ADD_SP_imm_T2    = 0xB000,
+        OP_SUB_SP_imm_T1    = 0xB080,
+        OP_BKPT             = 0xBE00,
+        OP_IT               = 0xBF00,
+        OP_NOP_T1           = 0xBF00,
+    } OpcodeID;
+
+    typedef enum {
+        OP_AND_reg_T2   = 0xEA00,
+        OP_TST_reg_T2   = 0xEA10,
+        OP_ORR_reg_T2   = 0xEA40,
+        OP_ORR_S_reg_T2 = 0xEA50,
+        OP_ASR_imm_T1   = 0xEA4F,
+        OP_LSL_imm_T1   = 0xEA4F,
+        OP_LSR_imm_T1   = 0xEA4F,
+        OP_ROR_imm_T1   = 0xEA4F,
+        OP_MVN_reg_T2   = 0xEA6F,
+        OP_EOR_reg_T2   = 0xEA80,
+        OP_ADD_reg_T3   = 0xEB00,
+        OP_ADD_S_reg_T3 = 0xEB10,
+        OP_SUB_reg_T2   = 0xEBA0,
+        OP_SUB_S_reg_T2 = 0xEBB0,
+        OP_CMP_reg_T2   = 0xEBB0,
+        OP_VSTR         = 0xED00,
+        OP_VLDR         = 0xED10,
+        OP_VMOV_StoC    = 0xEE00,
+        OP_VMOV_CtoS    = 0xEE10,
+        OP_VMUL_T2      = 0xEE20,
+        OP_VADD_T2      = 0xEE30,
+        OP_VSUB_T2      = 0xEE30,
+        OP_VDIV         = 0xEE80,
+        OP_VCMP_T1      = 0xEEB0,
+        OP_VCVT_FPIVFP  = 0xEEB0,
+        OP_VMOV_IMM_T2  = 0xEEB0,
+        OP_VMRS         = 0xEEB0,
+        OP_B_T4a        = 0xF000,
+        OP_AND_imm_T1   = 0xF000,
+        OP_TST_imm      = 0xF010,
+        OP_ORR_imm_T1   = 0xF040,
+        OP_MOV_imm_T2   = 0xF040,
+        OP_MVN_imm      = 0xF060,
+        OP_EOR_imm_T1   = 0xF080,
+        OP_ADD_imm_T3   = 0xF100,
+        OP_ADD_S_imm_T3 = 0xF110,
+        OP_CMN_imm      = 0xF110,
+        OP_SUB_imm_T3   = 0xF1A0,
+        OP_SUB_S_imm_T3 = 0xF1B0,
+        OP_CMP_imm_T2   = 0xF1B0,
+        OP_RSB_imm_T2   = 0xF1C0,
+        OP_ADD_imm_T4   = 0xF200,
+        OP_MOV_imm_T3   = 0xF240,
+        OP_SUB_imm_T4   = 0xF2A0,
+        OP_MOVT         = 0xF2C0,
+        OP_NOP_T2a      = 0xF3AF,
+        OP_LDRB_imm_T3  = 0xF810,
+        OP_LDRB_reg_T2  = 0xF810,
+        OP_LDRH_reg_T2  = 0xF830,
+        OP_LDRH_imm_T3  = 0xF830,
+        OP_STR_imm_T4   = 0xF840,
+        OP_STR_reg_T2   = 0xF840,
+        OP_LDR_imm_T4   = 0xF850,
+        OP_LDR_reg_T2   = 0xF850,
+        OP_LDRB_imm_T2  = 0xF890,
+        OP_LDRH_imm_T2  = 0xF8B0,
+        OP_STR_imm_T3   = 0xF8C0,
+        OP_LDR_imm_T3   = 0xF8D0,
+        OP_LSL_reg_T2   = 0xFA00,
+        OP_LSR_reg_T2   = 0xFA20,
+        OP_ASR_reg_T2   = 0xFA40,
+        OP_ROR_reg_T2   = 0xFA60,
+        OP_SMULL_T1     = 0xFB80,
+    } OpcodeID1;
+
+    typedef enum {
+        OP_VADD_T2b     = 0x0A00,
+        OP_VDIVb        = 0x0A00,
+        OP_VLDRb        = 0x0A00,
+        OP_VMOV_IMM_T2b = 0x0A00,
+        OP_VMUL_T2b     = 0x0A00,
+        OP_VSTRb        = 0x0A00,
+        OP_VMOV_CtoSb   = 0x0A10,
+        OP_VMOV_StoCb   = 0x0A10,
+        OP_VMRSb        = 0x0A10,
+        OP_VCMP_T1b     = 0x0A40,
+        OP_VCVT_FPIVFPb = 0x0A40,
+        OP_VSUB_T2b     = 0x0A40,
+        OP_NOP_T2b      = 0x8000,
+        OP_B_T4b        = 0x9000,
+    } OpcodeID2;
+
+    struct FourFours {
+        FourFours(unsigned f3, unsigned f2, unsigned f1, unsigned f0)
+        {
+            m_u.f0 = f0;
+            m_u.f1 = f1;
+            m_u.f2 = f2;
+            m_u.f3 = f3;
+        }
+
+        union {
+            unsigned value;
+            struct {
+                unsigned f0 : 4;
+                unsigned f1 : 4;
+                unsigned f2 : 4;
+                unsigned f3 : 4;
+            };
+        } m_u;
+    };
+
+    class ARMInstructionFormatter;
+
+    // false means else!
+    bool ifThenElseConditionBit(Condition condition, bool isIf)
+    {
+        return isIf ? (condition & 1) : !(condition & 1);
+    }
+    uint8_t ifThenElse(Condition condition, bool inst2if, bool inst3if, bool inst4if)
+    {
+        int mask = (ifThenElseConditionBit(condition, inst2if) << 3)
+            | (ifThenElseConditionBit(condition, inst3if) << 2)
+            | (ifThenElseConditionBit(condition, inst4if) << 1)
+            | 1;
+        ASSERT((condition != ConditionAL) || (mask & (mask - 1)));
+        return (condition << 4) | mask;
+    }
+    uint8_t ifThenElse(Condition condition, bool inst2if, bool inst3if)
+    {
+        int mask = (ifThenElseConditionBit(condition, inst2if) << 3)
+            | (ifThenElseConditionBit(condition, inst3if) << 2)
+            | 2;
+        ASSERT((condition != ConditionAL) || (mask & (mask - 1)));
+        return (condition << 4) | mask;
+    }
+    uint8_t ifThenElse(Condition condition, bool inst2if)
+    {
+        int mask = (ifThenElseConditionBit(condition, inst2if) << 3)
+            | 4;
+        ASSERT((condition != ConditionAL) || (mask & (mask - 1)));
+        return (condition << 4) | mask;
+    }
+
+    uint8_t ifThenElse(Condition condition)
+    {
+        int mask = 8;
+        ASSERT((condition != ConditionAL) || (mask & (mask - 1)));
+        return (condition << 4) | mask;
+    }
+
+public:
+
+    void add(RegisterID rd, RegisterID rn, ARMThumbImmediate imm)
+    {
+        // Rd can only be SP if Rn is also SP.
+        ASSERT((rd != ARMRegisters::sp) || (rn == ARMRegisters::sp));
+        ASSERT(rd != ARMRegisters::pc);
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(imm.isValid());
+
+        if (rn == ARMRegisters::sp) {
+            if (!(rd & 8) && imm.isUInt10()) {
+                m_formatter.oneWordOp5Reg3Imm8(OP_ADD_SP_imm_T1, rd, imm.getUInt10() >> 2);
+                return;
+            } else if ((rd == ARMRegisters::sp) && imm.isUInt9()) {
+                m_formatter.oneWordOp9Imm7(OP_ADD_SP_imm_T2, imm.getUInt9() >> 2);
+                return;
+            }
+        } else if (!((rd | rn) & 8)) {
+            if (imm.isUInt3()) {
+                m_formatter.oneWordOp7Reg3Reg3Reg3(OP_ADD_imm_T1, (RegisterID)imm.getUInt3(), rn, rd);
+                return;
+            } else if ((rd == rn) && imm.isUInt8()) {
+                m_formatter.oneWordOp5Reg3Imm8(OP_ADD_imm_T2, rd, imm.getUInt8());
+                return;
+            }
+        }
+
+        if (imm.isEncodedImm())
+            m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_ADD_imm_T3, rn, rd, imm);
+        else {
+            ASSERT(imm.isUInt12());
+            m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_ADD_imm_T4, rn, rd, imm);
+        }
+    }
+
+    void add(RegisterID rd, RegisterID rn, RegisterID rm, ShiftTypeAndAmount shift)
+    {
+        ASSERT((rd != ARMRegisters::sp) || (rn == ARMRegisters::sp));
+        ASSERT(rd != ARMRegisters::pc);
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_ADD_reg_T3, rn, FourFours(shift.hi4(), rd, shift.lo4(), rm));
+    }
+
+    // NOTE: In an IT block, add doesn't modify the flags register.
+    void add(RegisterID rd, RegisterID rn, RegisterID rm)
+    {
+        if (rd == rn)
+            m_formatter.oneWordOp8RegReg143(OP_ADD_reg_T2, rm, rd);
+        else if (rd == rm)
+            m_formatter.oneWordOp8RegReg143(OP_ADD_reg_T2, rn, rd);
+        else if (!((rd | rn | rm) & 8))
+            m_formatter.oneWordOp7Reg3Reg3Reg3(OP_ADD_reg_T1, rm, rn, rd);
+        else
+            add(rd, rn, rm, ShiftTypeAndAmount());
+    }
+
+    // Not allowed in an IT (if then) block.
+    void add_S(RegisterID rd, RegisterID rn, ARMThumbImmediate imm)
+    {
+        // Rd can only be SP if Rn is also SP.
+        ASSERT((rd != ARMRegisters::sp) || (rn == ARMRegisters::sp));
+        ASSERT(rd != ARMRegisters::pc);
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(imm.isEncodedImm());
+
+        if (!((rd | rn) & 8)) {
+            if (imm.isUInt3()) {
+                m_formatter.oneWordOp7Reg3Reg3Reg3(OP_ADD_imm_T1, (RegisterID)imm.getUInt3(), rn, rd);
+                return;
+            } else if ((rd == rn) && imm.isUInt8()) {
+                m_formatter.oneWordOp5Reg3Imm8(OP_ADD_imm_T2, rd, imm.getUInt8());
+                return;
+            }
+        }
+
+        m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_ADD_S_imm_T3, rn, rd, imm);
+    }
+
+    // Not allowed in an IT (if then) block?
+    void add_S(RegisterID rd, RegisterID rn, RegisterID rm, ShiftTypeAndAmount shift)
+    {
+        ASSERT((rd != ARMRegisters::sp) || (rn == ARMRegisters::sp));
+        ASSERT(rd != ARMRegisters::pc);
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_ADD_S_reg_T3, rn, FourFours(shift.hi4(), rd, shift.lo4(), rm));
+    }
+
+    // Not allowed in an IT (if then) block.
+    void add_S(RegisterID rd, RegisterID rn, RegisterID rm)
+    {
+        if (!((rd | rn | rm) & 8))
+            m_formatter.oneWordOp7Reg3Reg3Reg3(OP_ADD_reg_T1, rm, rn, rd);
+        else
+            add_S(rd, rn, rm, ShiftTypeAndAmount());
+    }
+
+    void ARM_and(RegisterID rd, RegisterID rn, ARMThumbImmediate imm)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rn));
+        ASSERT(imm.isEncodedImm());
+        m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_AND_imm_T1, rn, rd, imm);
+    }
+
+    void ARM_and(RegisterID rd, RegisterID rn, RegisterID rm, ShiftTypeAndAmount shift)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rn));
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_AND_reg_T2, rn, FourFours(shift.hi4(), rd, shift.lo4(), rm));
+    }
+
+    void ARM_and(RegisterID rd, RegisterID rn, RegisterID rm)
+    {
+        if ((rd == rn) && !((rd | rm) & 8))
+            m_formatter.oneWordOp10Reg3Reg3(OP_AND_reg_T1, rm, rd);
+        else if ((rd == rm) && !((rd | rn) & 8))
+            m_formatter.oneWordOp10Reg3Reg3(OP_AND_reg_T1, rn, rd);
+        else
+            ARM_and(rd, rn, rm, ShiftTypeAndAmount());
+    }
+
+    void asr(RegisterID rd, RegisterID rm, int32_t shiftAmount)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rm));
+        ShiftTypeAndAmount shift(SRType_ASR, shiftAmount);
+        m_formatter.twoWordOp16FourFours(OP_ASR_imm_T1, FourFours(shift.hi4(), rd, shift.lo4(), rm));
+    }
+
+    void asr(RegisterID rd, RegisterID rn, RegisterID rm)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rn));
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_ASR_reg_T2, rn, FourFours(0xf, rd, 0, rm));
+    }
+
+    // Only allowed in IT (if then) block if last instruction.
+    JmpSrc b()
+    {
+        m_formatter.twoWordOp16Op16(OP_B_T4a, OP_B_T4b);
+        return JmpSrc(m_formatter.size());
+    }
+    
+    // Only allowed in IT (if then) block if last instruction.
+    JmpSrc blx(RegisterID rm)
+    {
+        ASSERT(rm != ARMRegisters::pc);
+        m_formatter.oneWordOp8RegReg143(OP_BLX, rm, (RegisterID)8);
+        return JmpSrc(m_formatter.size());
+    }
+
+    // Only allowed in IT (if then) block if last instruction.
+    JmpSrc bx(RegisterID rm)
+    {
+        m_formatter.oneWordOp8RegReg143(OP_BX, rm, (RegisterID)0);
+        return JmpSrc(m_formatter.size());
+    }
+
+    void bkpt(uint8_t imm=0)
+    {
+        m_formatter.oneWordOp8Imm8(OP_BKPT, imm);
+    }
+
+    void cmn(RegisterID rn, ARMThumbImmediate imm)
+    {
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(imm.isEncodedImm());
+
+        m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_CMN_imm, rn, (RegisterID)0xf, imm);
+    }
+
+    void cmp(RegisterID rn, ARMThumbImmediate imm)
+    {
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(imm.isEncodedImm());
+
+        if (!(rn & 8) && imm.isUInt8())
+            m_formatter.oneWordOp5Reg3Imm8(OP_CMP_imm_T1, rn, imm.getUInt8());
+        else
+            m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_CMP_imm_T2, rn, (RegisterID)0xf, imm);
+    }
+
+    void cmp(RegisterID rn, RegisterID rm, ShiftTypeAndAmount shift)
+    {
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_CMP_reg_T2, rn, FourFours(shift.hi4(), 0xf, shift.lo4(), rm));
+    }
+
+    void cmp(RegisterID rn, RegisterID rm)
+    {
+        if ((rn | rm) & 8)
+            cmp(rn, rm, ShiftTypeAndAmount());
+        else
+            m_formatter.oneWordOp10Reg3Reg3(OP_CMP_reg_T1, rm, rn);
+    }
+
+    // xor is not spelled with an 'e'. :-(
+    void eor(RegisterID rd, RegisterID rn, ARMThumbImmediate imm)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rn));
+        ASSERT(imm.isEncodedImm());
+        m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_EOR_imm_T1, rn, rd, imm);
+    }
+
+    // xor is not spelled with an 'e'. :-(
+    void eor(RegisterID rd, RegisterID rn, RegisterID rm, ShiftTypeAndAmount shift)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rn));
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_EOR_reg_T2, rn, FourFours(shift.hi4(), rd, shift.lo4(), rm));
+    }
+
+    // xor is not spelled with an 'e'. :-(
+    void eor(RegisterID rd, RegisterID rn, RegisterID rm)
+    {
+        if ((rd == rn) && !((rd | rm) & 8))
+            m_formatter.oneWordOp10Reg3Reg3(OP_EOR_reg_T1, rm, rd);
+        else if ((rd == rm) && !((rd | rn) & 8))
+            m_formatter.oneWordOp10Reg3Reg3(OP_EOR_reg_T1, rn, rd);
+        else
+            eor(rd, rn, rm, ShiftTypeAndAmount());
+    }
+
+    void it(Condition cond)
+    {
+        m_formatter.oneWordOp8Imm8(OP_IT, ifThenElse(cond));
+    }
+
+    void it(Condition cond, bool inst2if)
+    {
+        m_formatter.oneWordOp8Imm8(OP_IT, ifThenElse(cond, inst2if));
+    }
+
+    void it(Condition cond, bool inst2if, bool inst3if)
+    {
+        m_formatter.oneWordOp8Imm8(OP_IT, ifThenElse(cond, inst2if, inst3if));
+    }
+
+    void it(Condition cond, bool inst2if, bool inst3if, bool inst4if)
+    {
+        m_formatter.oneWordOp8Imm8(OP_IT, ifThenElse(cond, inst2if, inst3if, inst4if));
+    }
+
+    // rt == ARMRegisters::pc only allowed if last instruction in IT (if then) block.
+    void ldr(RegisterID rt, RegisterID rn, ARMThumbImmediate imm)
+    {
+        ASSERT(rn != ARMRegisters::pc); // LDR (literal)
+        ASSERT(imm.isUInt12());
+
+        if (!((rt | rn) & 8) && imm.isUInt7())
+            m_formatter.oneWordOp5Imm5Reg3Reg3(OP_LDR_imm_T1, imm.getUInt7() >> 2, rn, rt);
+        else if ((rn == ARMRegisters::sp) && !(rt & 8) && imm.isUInt10())
+            m_formatter.oneWordOp5Reg3Imm8(OP_LDR_imm_T2, rt, imm.getUInt10() >> 2);
+        else
+            m_formatter.twoWordOp12Reg4Reg4Imm12(OP_LDR_imm_T3, rn, rt, imm.getUInt12());
+    }
+
+    // If index is set, this is a regular offset or a pre-indexed load;
+    // if index is not set then is is a post-index load.
+    //
+    // If wback is set rn is updated - this is a pre or post index load,
+    // if wback is not set this is a regular offset memory access.
+    //
+    // (-255 <= offset <= 255)
+    // _reg = REG[rn]
+    // _tmp = _reg + offset
+    // MEM[index ? _tmp : _reg] = REG[rt]
+    // if (wback) REG[rn] = _tmp
+    void ldr(RegisterID rt, RegisterID rn, int offset, bool index, bool wback)
+    {
+        ASSERT(rt != ARMRegisters::pc);
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(index || wback);
+        ASSERT(!wback | (rt != rn));
+    
+        bool add = true;
+        if (offset < 0) {
+            add = false;
+            offset = -offset;
+        }
+        ASSERT((offset & ~0xff) == 0);
+        
+        offset |= (wback << 8);
+        offset |= (add   << 9);
+        offset |= (index << 10);
+        offset |= (1 << 11);
+        
+        m_formatter.twoWordOp12Reg4Reg4Imm12(OP_LDR_imm_T4, rn, rt, offset);
+    }
+
+    // rt == ARMRegisters::pc only allowed if last instruction in IT (if then) block.
+    void ldr(RegisterID rt, RegisterID rn, RegisterID rm, unsigned shift=0)
+    {
+        ASSERT(rn != ARMRegisters::pc); // LDR (literal)
+        ASSERT(!BadReg(rm));
+        ASSERT(shift <= 3);
+
+        if (!shift && !((rt | rn | rm) & 8))
+            m_formatter.oneWordOp7Reg3Reg3Reg3(OP_LDR_reg_T1, rm, rn, rt);
+        else
+            m_formatter.twoWordOp12Reg4FourFours(OP_LDR_reg_T2, rn, FourFours(rt, 0, shift, rm));
+    }
+
+    // rt == ARMRegisters::pc only allowed if last instruction in IT (if then) block.
+    void ldrh(RegisterID rt, RegisterID rn, ARMThumbImmediate imm)
+    {
+        ASSERT(rn != ARMRegisters::pc); // LDR (literal)
+        ASSERT(imm.isUInt12());
+
+        if (!((rt | rn) & 8) && imm.isUInt6())
+            m_formatter.oneWordOp5Imm5Reg3Reg3(OP_LDRH_imm_T1, imm.getUInt6() >> 2, rn, rt);
+        else
+            m_formatter.twoWordOp12Reg4Reg4Imm12(OP_LDRH_imm_T2, rn, rt, imm.getUInt12());
+    }
+
+    // If index is set, this is a regular offset or a pre-indexed load;
+    // if index is not set then is is a post-index load.
+    //
+    // If wback is set rn is updated - this is a pre or post index load,
+    // if wback is not set this is a regular offset memory access.
+    //
+    // (-255 <= offset <= 255)
+    // _reg = REG[rn]
+    // _tmp = _reg + offset
+    // MEM[index ? _tmp : _reg] = REG[rt]
+    // if (wback) REG[rn] = _tmp
+    void ldrh(RegisterID rt, RegisterID rn, int offset, bool index, bool wback)
+    {
+        ASSERT(rt != ARMRegisters::pc);
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(index || wback);
+        ASSERT(!wback | (rt != rn));
+    
+        bool add = true;
+        if (offset < 0) {
+            add = false;
+            offset = -offset;
+        }
+        ASSERT((offset & ~0xff) == 0);
+        
+        offset |= (wback << 8);
+        offset |= (add   << 9);
+        offset |= (index << 10);
+        offset |= (1 << 11);
+        
+        m_formatter.twoWordOp12Reg4Reg4Imm12(OP_LDRH_imm_T3, rn, rt, offset);
+    }
+
+    void ldrh(RegisterID rt, RegisterID rn, RegisterID rm, unsigned shift=0)
+    {
+        ASSERT(!BadReg(rt));   // Memory hint
+        ASSERT(rn != ARMRegisters::pc); // LDRH (literal)
+        ASSERT(!BadReg(rm));
+        ASSERT(shift <= 3);
+
+        if (!shift && !((rt | rn | rm) & 8))
+            m_formatter.oneWordOp7Reg3Reg3Reg3(OP_LDRH_reg_T1, rm, rn, rt);
+        else
+            m_formatter.twoWordOp12Reg4FourFours(OP_LDRH_reg_T2, rn, FourFours(rt, 0, shift, rm));
+    }
+
+    void ldrb(RegisterID rt, RegisterID rn, ARMThumbImmediate imm)
+    {
+        ASSERT(rn != ARMRegisters::pc); // LDR (literal)
+        ASSERT(imm.isUInt12());
+
+        if (!((rt | rn) & 8) && imm.isUInt5())
+            m_formatter.oneWordOp5Imm5Reg3Reg3(OP_LDRB_imm_T1, imm.getUInt5(), rn, rt);
+        else
+            m_formatter.twoWordOp12Reg4Reg4Imm12(OP_LDRB_imm_T2, rn, rt, imm.getUInt12());
+    }
+
+    void ldrb(RegisterID rt, RegisterID rn, int offset, bool index, bool wback)
+    {
+        ASSERT(rt != ARMRegisters::pc);
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(index || wback);
+        ASSERT(!wback | (rt != rn));
+
+        bool add = true;
+        if (offset < 0) {
+            add = false;
+            offset = -offset;
+        }
+
+        ASSERT(!(offset & ~0xff));
+
+        offset |= (wback << 8);
+        offset |= (add   << 9);
+        offset |= (index << 10);
+        offset |= (1 << 11);
+
+        m_formatter.twoWordOp12Reg4Reg4Imm12(OP_LDRB_imm_T3, rn, rt, offset);
+    }
+
+    void ldrb(RegisterID rt, RegisterID rn, RegisterID rm, unsigned shift = 0)
+    {
+        ASSERT(rn != ARMRegisters::pc); // LDR (literal)
+        ASSERT(!BadReg(rm));
+        ASSERT(shift <= 3);
+
+        if (!shift && !((rt | rn | rm) & 8))
+            m_formatter.oneWordOp7Reg3Reg3Reg3(OP_LDRB_reg_T1, rm, rn, rt);
+        else
+            m_formatter.twoWordOp12Reg4FourFours(OP_LDRB_reg_T2, rn, FourFours(rt, 0, shift, rm));
+    }
+
+    void lsl(RegisterID rd, RegisterID rm, int32_t shiftAmount)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rm));
+        ShiftTypeAndAmount shift(SRType_LSL, shiftAmount);
+        m_formatter.twoWordOp16FourFours(OP_LSL_imm_T1, FourFours(shift.hi4(), rd, shift.lo4(), rm));
+    }
+
+    void lsl(RegisterID rd, RegisterID rn, RegisterID rm)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rn));
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_LSL_reg_T2, rn, FourFours(0xf, rd, 0, rm));
+    }
+
+    void lsr(RegisterID rd, RegisterID rm, int32_t shiftAmount)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rm));
+        ShiftTypeAndAmount shift(SRType_LSR, shiftAmount);
+        m_formatter.twoWordOp16FourFours(OP_LSR_imm_T1, FourFours(shift.hi4(), rd, shift.lo4(), rm));
+    }
+
+    void lsr(RegisterID rd, RegisterID rn, RegisterID rm)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rn));
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_LSR_reg_T2, rn, FourFours(0xf, rd, 0, rm));
+    }
+
+    void movT3(RegisterID rd, ARMThumbImmediate imm)
+    {
+        ASSERT(imm.isValid());
+        ASSERT(!imm.isEncodedImm());
+        ASSERT(!BadReg(rd));
+        
+        m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_MOV_imm_T3, imm.m_value.imm4, rd, imm);
+    }
+
+     void mov(RegisterID rd, ARMThumbImmediate imm)
+    {
+        ASSERT(imm.isValid());
+        ASSERT(!BadReg(rd));
+        
+        if ((rd < 8) && imm.isUInt8())
+            m_formatter.oneWordOp5Reg3Imm8(OP_MOV_imm_T1, rd, imm.getUInt8());
+        else if (imm.isEncodedImm())
+            m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_MOV_imm_T2, 0xf, rd, imm);
+        else
+            movT3(rd, imm);
+    }
+
+   void mov(RegisterID rd, RegisterID rm)
+    {
+        m_formatter.oneWordOp8RegReg143(OP_MOV_reg_T1, rm, rd);
+    }
+
+    void movt(RegisterID rd, ARMThumbImmediate imm)
+    {
+        ASSERT(imm.isUInt16());
+        ASSERT(!BadReg(rd));
+        m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_MOVT, imm.m_value.imm4, rd, imm);
+    }
+
+    void mvn(RegisterID rd, ARMThumbImmediate imm)
+    {
+        ASSERT(imm.isEncodedImm());
+        ASSERT(!BadReg(rd));
+        
+        m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_MVN_imm, 0xf, rd, imm);
+    }
+
+    void mvn(RegisterID rd, RegisterID rm, ShiftTypeAndAmount shift)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp16FourFours(OP_MVN_reg_T2, FourFours(shift.hi4(), rd, shift.lo4(), rm));
+    }
+
+    void mvn(RegisterID rd, RegisterID rm)
+    {
+        if (!((rd | rm) & 8))
+            m_formatter.oneWordOp10Reg3Reg3(OP_MVN_reg_T1, rm, rd);
+        else
+            mvn(rd, rm, ShiftTypeAndAmount());
+    }
+
+    void neg(RegisterID rd, RegisterID rm)
+    {
+        ARMThumbImmediate zero = ARMThumbImmediate::makeUInt12(0);
+        sub(rd, zero, rm);
+    }
+
+    void orr(RegisterID rd, RegisterID rn, ARMThumbImmediate imm)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rn));
+        ASSERT(imm.isEncodedImm());
+        m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_ORR_imm_T1, rn, rd, imm);
+    }
+
+    void orr(RegisterID rd, RegisterID rn, RegisterID rm, ShiftTypeAndAmount shift)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rn));
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_ORR_reg_T2, rn, FourFours(shift.hi4(), rd, shift.lo4(), rm));
+    }
+
+    void orr(RegisterID rd, RegisterID rn, RegisterID rm)
+    {
+        if ((rd == rn) && !((rd | rm) & 8))
+            m_formatter.oneWordOp10Reg3Reg3(OP_ORR_reg_T1, rm, rd);
+        else if ((rd == rm) && !((rd | rn) & 8))
+            m_formatter.oneWordOp10Reg3Reg3(OP_ORR_reg_T1, rn, rd);
+        else
+            orr(rd, rn, rm, ShiftTypeAndAmount());
+    }
+
+    void orr_S(RegisterID rd, RegisterID rn, RegisterID rm, ShiftTypeAndAmount shift)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rn));
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_ORR_S_reg_T2, rn, FourFours(shift.hi4(), rd, shift.lo4(), rm));
+    }
+
+    void orr_S(RegisterID rd, RegisterID rn, RegisterID rm)
+    {
+        if ((rd == rn) && !((rd | rm) & 8))
+            m_formatter.oneWordOp10Reg3Reg3(OP_ORR_reg_T1, rm, rd);
+        else if ((rd == rm) && !((rd | rn) & 8))
+            m_formatter.oneWordOp10Reg3Reg3(OP_ORR_reg_T1, rn, rd);
+        else
+            orr_S(rd, rn, rm, ShiftTypeAndAmount());
+    }
+
+    void ror(RegisterID rd, RegisterID rm, int32_t shiftAmount)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rm));
+        ShiftTypeAndAmount shift(SRType_ROR, shiftAmount);
+        m_formatter.twoWordOp16FourFours(OP_ROR_imm_T1, FourFours(shift.hi4(), rd, shift.lo4(), rm));
+    }
+
+    void ror(RegisterID rd, RegisterID rn, RegisterID rm)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rn));
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_ROR_reg_T2, rn, FourFours(0xf, rd, 0, rm));
+    }
+
+    void smull(RegisterID rdLo, RegisterID rdHi, RegisterID rn, RegisterID rm)
+    {
+        ASSERT(!BadReg(rdLo));
+        ASSERT(!BadReg(rdHi));
+        ASSERT(!BadReg(rn));
+        ASSERT(!BadReg(rm));
+        ASSERT(rdLo != rdHi);
+        m_formatter.twoWordOp12Reg4FourFours(OP_SMULL_T1, rn, FourFours(rdLo, rdHi, 0, rm));
+    }
+
+    // rt == ARMRegisters::pc only allowed if last instruction in IT (if then) block.
+    void str(RegisterID rt, RegisterID rn, ARMThumbImmediate imm)
+    {
+        ASSERT(rt != ARMRegisters::pc);
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(imm.isUInt12());
+
+        if (!((rt | rn) & 8) && imm.isUInt7())
+            m_formatter.oneWordOp5Imm5Reg3Reg3(OP_STR_imm_T1, imm.getUInt7() >> 2, rn, rt);
+        else if ((rn == ARMRegisters::sp) && !(rt & 8) && imm.isUInt10())
+            m_formatter.oneWordOp5Reg3Imm8(OP_STR_imm_T2, rt, imm.getUInt10() >> 2);
+        else
+            m_formatter.twoWordOp12Reg4Reg4Imm12(OP_STR_imm_T3, rn, rt, imm.getUInt12());
+    }
+
+    // If index is set, this is a regular offset or a pre-indexed store;
+    // if index is not set then is is a post-index store.
+    //
+    // If wback is set rn is updated - this is a pre or post index store,
+    // if wback is not set this is a regular offset memory access.
+    //
+    // (-255 <= offset <= 255)
+    // _reg = REG[rn]
+    // _tmp = _reg + offset
+    // MEM[index ? _tmp : _reg] = REG[rt]
+    // if (wback) REG[rn] = _tmp
+    void str(RegisterID rt, RegisterID rn, int offset, bool index, bool wback)
+    {
+        ASSERT(rt != ARMRegisters::pc);
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(index || wback);
+        ASSERT(!wback | (rt != rn));
+    
+        bool add = true;
+        if (offset < 0) {
+            add = false;
+            offset = -offset;
+        }
+        ASSERT((offset & ~0xff) == 0);
+        
+        offset |= (wback << 8);
+        offset |= (add   << 9);
+        offset |= (index << 10);
+        offset |= (1 << 11);
+        
+        m_formatter.twoWordOp12Reg4Reg4Imm12(OP_STR_imm_T4, rn, rt, offset);
+    }
+
+    // rt == ARMRegisters::pc only allowed if last instruction in IT (if then) block.
+    void str(RegisterID rt, RegisterID rn, RegisterID rm, unsigned shift=0)
+    {
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(!BadReg(rm));
+        ASSERT(shift <= 3);
+
+        if (!shift && !((rt | rn | rm) & 8))
+            m_formatter.oneWordOp7Reg3Reg3Reg3(OP_STR_reg_T1, rm, rn, rt);
+        else
+            m_formatter.twoWordOp12Reg4FourFours(OP_STR_reg_T2, rn, FourFours(rt, 0, shift, rm));
+    }
+
+    void sub(RegisterID rd, RegisterID rn, ARMThumbImmediate imm)
+    {
+        // Rd can only be SP if Rn is also SP.
+        ASSERT((rd != ARMRegisters::sp) || (rn == ARMRegisters::sp));
+        ASSERT(rd != ARMRegisters::pc);
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(imm.isValid());
+
+        if ((rn == ARMRegisters::sp) && (rd == ARMRegisters::sp) && imm.isUInt9()) {
+            m_formatter.oneWordOp9Imm7(OP_SUB_SP_imm_T1, imm.getUInt9() >> 2);
+            return;
+        } else if (!((rd | rn) & 8)) {
+            if (imm.isUInt3()) {
+                m_formatter.oneWordOp7Reg3Reg3Reg3(OP_SUB_imm_T1, (RegisterID)imm.getUInt3(), rn, rd);
+                return;
+            } else if ((rd == rn) && imm.isUInt8()) {
+                m_formatter.oneWordOp5Reg3Imm8(OP_SUB_imm_T2, rd, imm.getUInt8());
+                return;
+            }
+        }
+
+        if (imm.isEncodedImm())
+            m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_SUB_imm_T3, rn, rd, imm);
+        else {
+            ASSERT(imm.isUInt12());
+            m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_SUB_imm_T4, rn, rd, imm);
+        }
+    }
+
+    void sub(RegisterID rd, ARMThumbImmediate imm, RegisterID rn)
+    {
+        ASSERT(rd != ARMRegisters::pc);
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(imm.isValid());
+        ASSERT(imm.isUInt12());
+
+        if (!((rd | rn) & 8) && !imm.getUInt12())
+            m_formatter.oneWordOp10Reg3Reg3(OP_RSB_imm_T1, rn, rd);
+        else
+            m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_RSB_imm_T2, rn, rd, imm);
+    }
+
+    void sub(RegisterID rd, RegisterID rn, RegisterID rm, ShiftTypeAndAmount shift)
+    {
+        ASSERT((rd != ARMRegisters::sp) || (rn == ARMRegisters::sp));
+        ASSERT(rd != ARMRegisters::pc);
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_SUB_reg_T2, rn, FourFours(shift.hi4(), rd, shift.lo4(), rm));
+    }
+
+    // NOTE: In an IT block, add doesn't modify the flags register.
+    void sub(RegisterID rd, RegisterID rn, RegisterID rm)
+    {
+        if (!((rd | rn | rm) & 8))
+            m_formatter.oneWordOp7Reg3Reg3Reg3(OP_SUB_reg_T1, rm, rn, rd);
+        else
+            sub(rd, rn, rm, ShiftTypeAndAmount());
+    }
+
+    // Not allowed in an IT (if then) block.
+    void sub_S(RegisterID rd, RegisterID rn, ARMThumbImmediate imm)
+    {
+        // Rd can only be SP if Rn is also SP.
+        ASSERT((rd != ARMRegisters::sp) || (rn == ARMRegisters::sp));
+        ASSERT(rd != ARMRegisters::pc);
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(imm.isValid());
+
+        if ((rn == ARMRegisters::sp) && (rd == ARMRegisters::sp) && imm.isUInt9()) {
+            m_formatter.oneWordOp9Imm7(OP_SUB_SP_imm_T1, imm.getUInt9() >> 2);
+            return;
+        } else if (!((rd | rn) & 8)) {
+            if (imm.isUInt3()) {
+                m_formatter.oneWordOp7Reg3Reg3Reg3(OP_SUB_imm_T1, (RegisterID)imm.getUInt3(), rn, rd);
+                return;
+            } else if ((rd == rn) && imm.isUInt8()) {
+                m_formatter.oneWordOp5Reg3Imm8(OP_SUB_imm_T2, rd, imm.getUInt8());
+                return;
+            }
+        }
+
+        m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_SUB_S_imm_T3, rn, rd, imm);
+    }
+
+    // Not allowed in an IT (if then) block?
+    void sub_S(RegisterID rd, RegisterID rn, RegisterID rm, ShiftTypeAndAmount shift)
+    {
+        ASSERT((rd != ARMRegisters::sp) || (rn == ARMRegisters::sp));
+        ASSERT(rd != ARMRegisters::pc);
+        ASSERT(rn != ARMRegisters::pc);
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_SUB_S_reg_T2, rn, FourFours(shift.hi4(), rd, shift.lo4(), rm));
+    }
+
+    // Not allowed in an IT (if then) block.
+    void sub_S(RegisterID rd, RegisterID rn, RegisterID rm)
+    {
+        if (!((rd | rn | rm) & 8))
+            m_formatter.oneWordOp7Reg3Reg3Reg3(OP_SUB_reg_T1, rm, rn, rd);
+        else
+            sub_S(rd, rn, rm, ShiftTypeAndAmount());
+    }
+
+    void tst(RegisterID rn, ARMThumbImmediate imm)
+    {
+        ASSERT(!BadReg(rn));
+        ASSERT(imm.isEncodedImm());
+
+        m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_TST_imm, rn, (RegisterID)0xf, imm);
+    }
+
+    void tst(RegisterID rn, RegisterID rm, ShiftTypeAndAmount shift)
+    {
+        ASSERT(!BadReg(rn));
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_TST_reg_T2, rn, FourFours(shift.hi4(), 0xf, shift.lo4(), rm));
+    }
+
+    void tst(RegisterID rn, RegisterID rm)
+    {
+        if ((rn | rm) & 8)
+            tst(rn, rm, ShiftTypeAndAmount());
+        else
+            m_formatter.oneWordOp10Reg3Reg3(OP_TST_reg_T1, rm, rn);
+    }
+
+    void vadd_F64(FPDoubleRegisterID rd, FPDoubleRegisterID rn, FPDoubleRegisterID rm)
+    {
+        m_formatter.vfpOp(OP_VADD_T2, OP_VADD_T2b, true, rn, rd, rm);
+    }
+
+    void vcmp_F64(FPDoubleRegisterID rd, FPDoubleRegisterID rm)
+    {
+        m_formatter.vfpOp(OP_VCMP_T1, OP_VCMP_T1b, true, VFPOperand(4), rd, rm);
+    }
+
+    void vcvt_F64_S32(FPDoubleRegisterID rd, FPSingleRegisterID rm)
+    {
+        // boolean values are 64bit (toInt, unsigned, roundZero)
+        m_formatter.vfpOp(OP_VCVT_FPIVFP, OP_VCVT_FPIVFPb, true, vcvtOp(false, false, false), rd, rm);
+    }
+
+    void vcvtr_S32_F64(FPSingleRegisterID rd, FPDoubleRegisterID rm)
+    {
+        // boolean values are 64bit (toInt, unsigned, roundZero)
+        m_formatter.vfpOp(OP_VCVT_FPIVFP, OP_VCVT_FPIVFPb, true, vcvtOp(true, false, true), rd, rm);
+    }
+
+    void vdiv_F64(FPDoubleRegisterID rd, FPDoubleRegisterID rn, FPDoubleRegisterID rm)
+    {
+        m_formatter.vfpOp(OP_VDIV, OP_VDIVb, true, rn, rd, rm);
+    }
+
+    void vldr(FPDoubleRegisterID rd, RegisterID rn, int32_t imm)
+    {
+        m_formatter.vfpMemOp(OP_VLDR, OP_VLDRb, true, rn, rd, imm);
+    }
+
+    void vmov_F64_0(FPDoubleRegisterID rd)
+    {
+        m_formatter.vfpOp(OP_VMOV_IMM_T2, OP_VMOV_IMM_T2b, true, VFPOperand(0), rd, VFPOperand(0));
+    }
+
+    void vmov(RegisterID rd, FPSingleRegisterID rn)
+    {
+        ASSERT(!BadReg(rd));
+        m_formatter.vfpOp(OP_VMOV_CtoS, OP_VMOV_CtoSb, false, rn, rd, VFPOperand(0));
+    }
+
+    void vmov(FPSingleRegisterID rd, RegisterID rn)
+    {
+        ASSERT(!BadReg(rn));
+        m_formatter.vfpOp(OP_VMOV_StoC, OP_VMOV_StoCb, false, rd, rn, VFPOperand(0));
+    }
+
+    void vmrs(RegisterID reg = ARMRegisters::pc)
+    {
+        ASSERT(reg != ARMRegisters::sp);
+        m_formatter.vfpOp(OP_VMRS, OP_VMRSb, false, VFPOperand(1), VFPOperand(0x10 | reg), VFPOperand(0));
+    }
+
+    void vmul_F64(FPDoubleRegisterID rd, FPDoubleRegisterID rn, FPDoubleRegisterID rm)
+    {
+        m_formatter.vfpOp(OP_VMUL_T2, OP_VMUL_T2b, true, rn, rd, rm);
+    }
+
+    void vstr(FPDoubleRegisterID rd, RegisterID rn, int32_t imm)
+    {
+        m_formatter.vfpMemOp(OP_VSTR, OP_VSTRb, true, rn, rd, imm);
+    }
+
+    void vsub_F64(FPDoubleRegisterID rd, FPDoubleRegisterID rn, FPDoubleRegisterID rm)
+    {
+        m_formatter.vfpOp(OP_VSUB_T2, OP_VSUB_T2b, true, rn, rd, rm);
+    }
+
+    JmpDst label()
+    {
+        return JmpDst(m_formatter.size());
+    }
+    
+    JmpDst align(int alignment)
+    {
+        while (!m_formatter.isAligned(alignment))
+            bkpt();
+
+        return label();
+    }
+    
+    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;
+    }
+    
+    // Assembler admin methods:
+
+    size_t size() const
+    {
+        return m_formatter.size();
+    }
+
+    void* executableCopy(ExecutablePool* allocator)
+    {
+        void* copy = m_formatter.executableCopy(allocator);
+
+        unsigned jumpCount = m_jumpsToLink.size();
+        for (unsigned i = 0; i < jumpCount; ++i) {
+            uint16_t* location = reinterpret_cast<uint16_t*>(reinterpret_cast<intptr_t>(copy) + m_jumpsToLink[i].from);
+            uint16_t* target = reinterpret_cast<uint16_t*>(reinterpret_cast<intptr_t>(copy) + m_jumpsToLink[i].to);
+            linkJumpAbsolute(location, target);
+        }
+        m_jumpsToLink.clear();
+
+        ASSERT(copy);
+        return copy;
+    }
+
+    static unsigned getCallReturnOffset(JmpSrc call)
+    {
+        ASSERT(call.m_offset >= 0);
+        return call.m_offset;
+    }
+
+    // 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(to.m_offset != -1);
+        ASSERT(from.m_offset != -1);
+        m_jumpsToLink.append(LinkRecord(from.m_offset, to.m_offset));
+    }
+
+    static void linkJump(void* code, JmpSrc from, void* to)
+    {
+        ASSERT(from.m_offset != -1);
+        
+        uint16_t* location = reinterpret_cast<uint16_t*>(reinterpret_cast<intptr_t>(code) + from.m_offset);
+        linkJumpAbsolute(location, to);
+    }
+
+    // bah, this mathod should really be static, since it is used by the LinkBuffer.
+    // return a bool saying whether the link was successful?
+    static void linkCall(void* code, JmpSrc from, void* to)
+    {
+        ASSERT(!(reinterpret_cast<intptr_t>(code) & 1));
+        ASSERT(from.m_offset != -1);
+        ASSERT(reinterpret_cast<intptr_t>(to) & 1);
+
+        setPointer(reinterpret_cast<uint16_t*>(reinterpret_cast<intptr_t>(code) + from.m_offset) - 1, to);
+    }
+
+    static void linkPointer(void* code, JmpDst where, void* value)
+    {
+        setPointer(reinterpret_cast<char*>(code) + where.m_offset, value);
+    }
+
+    static void relinkJump(void* from, void* to)
+    {
+        ASSERT(!(reinterpret_cast<intptr_t>(from) & 1));
+        ASSERT(!(reinterpret_cast<intptr_t>(to) & 1));
+
+        linkJumpAbsolute(reinterpret_cast<uint16_t*>(from), to);
+
+        ExecutableAllocator::cacheFlush(reinterpret_cast<uint16_t*>(from) - 5, 5 * sizeof(uint16_t));
+    }
+    
+    static void relinkCall(void* from, void* to)
+    {
+        ASSERT(!(reinterpret_cast<intptr_t>(from) & 1));
+        ASSERT(reinterpret_cast<intptr_t>(to) & 1);
+
+        setPointer(reinterpret_cast<uint16_t*>(from) - 1, to);
+
+        ExecutableAllocator::cacheFlush(reinterpret_cast<uint16_t*>(from) - 5, 4 * sizeof(uint16_t));
+    }
+
+    static void repatchInt32(void* where, int32_t value)
+    {
+        ASSERT(!(reinterpret_cast<intptr_t>(where) & 1));
+        
+        setInt32(where, value);
+
+        ExecutableAllocator::cacheFlush(reinterpret_cast<uint16_t*>(where) - 4, 4 * sizeof(uint16_t));
+    }
+
+    static void repatchPointer(void* where, void* value)
+    {
+        ASSERT(!(reinterpret_cast<intptr_t>(where) & 1));
+        
+        setPointer(where, value);
+
+        ExecutableAllocator::cacheFlush(reinterpret_cast<uint16_t*>(where) - 4, 4 * sizeof(uint16_t));
+    }
+
+    static void repatchLoadPtrToLEA(void* where)
+    {
+        ASSERT(!(reinterpret_cast<intptr_t>(where) & 1));
+        uint16_t* loadOp = reinterpret_cast<uint16_t*>(where) + 4;
+
+        ASSERT((loadOp[0] & 0xfff0) == OP_LDR_reg_T2);
+        ASSERT((loadOp[1] & 0x0ff0) == 0);
+        int rn = loadOp[0] & 0xf;
+        int rt = loadOp[1] >> 12;
+        int rm = loadOp[1] & 0xf;
+
+        loadOp[0] = OP_ADD_reg_T3 | rn;
+        loadOp[1] = rt << 8 | rm;
+        ExecutableAllocator::cacheFlush(loadOp, sizeof(uint32_t));
+    }
+
+private:
+    // VFP operations commonly take one or more 5-bit operands, typically representing a
+    // floating point register number.  This will commonly be encoded in the instruction
+    // in two parts, with one single bit field, and one 4-bit field.  In the case of
+    // double precision operands the high bit of the register number will be encoded
+    // separately, and for single precision operands the high bit of the register number
+    // will be encoded individually.
+    // VFPOperand encapsulates a 5-bit VFP operand, with bits 0..3 containing the 4-bit
+    // field to be encoded together in the instruction (the low 4-bits of a double
+    // register number, or the high 4-bits of a single register number), and bit 4
+    // contains the bit value to be encoded individually.
+    struct VFPOperand {
+        explicit VFPOperand(uint32_t value)
+            : m_value(value)
+        {
+            ASSERT(!(m_value & ~0x1f));
+        }
+
+        VFPOperand(FPDoubleRegisterID reg)
+            : m_value(reg)
+        {
+        }
+
+        VFPOperand(RegisterID reg)
+            : m_value(reg)
+        {
+        }
+
+        VFPOperand(FPSingleRegisterID reg)
+            : m_value(((reg & 1) << 4) | (reg >> 1)) // rotate the lowest bit of 'reg' to the top.
+        {
+        }
+
+        uint32_t bits1()
+        {
+            return m_value >> 4;
+        }
+
+        uint32_t bits4()
+        {
+            return m_value & 0xf;
+        }
+
+        uint32_t m_value;
+    };
+
+    VFPOperand vcvtOp(bool toInteger, bool isUnsigned, bool isRoundZero)
+    {
+        // Cannot specify rounding when converting to float.
+        ASSERT(toInteger || !isRoundZero);
+
+        uint32_t op = 0x8;
+        if (toInteger) {
+            // opc2 indicates both toInteger & isUnsigned.
+            op |= isUnsigned ? 0x4 : 0x5;
+            // 'op' field in instruction is isRoundZero
+            if (isRoundZero)
+                op |= 0x10;
+        } else {
+            // 'op' field in instruction is isUnsigned
+            if (!isUnsigned)
+                op |= 0x10;
+        }
+        return VFPOperand(op);
+    }
+
+    static void setInt32(void* code, uint32_t value)
+    {
+        uint16_t* location = reinterpret_cast<uint16_t*>(code);
+        ASSERT(isMOV_imm_T3(location - 4) && isMOVT(location - 2));
+
+        ARMThumbImmediate lo16 = ARMThumbImmediate::makeUInt16(static_cast<uint16_t>(value));
+        ARMThumbImmediate hi16 = ARMThumbImmediate::makeUInt16(static_cast<uint16_t>(value >> 16));
+        location[-4] = twoWordOp5i6Imm4Reg4EncodedImmFirst(OP_MOV_imm_T3, lo16);
+        location[-3] = twoWordOp5i6Imm4Reg4EncodedImmSecond((location[-3] >> 8) & 0xf, lo16);
+        location[-2] = twoWordOp5i6Imm4Reg4EncodedImmFirst(OP_MOVT, hi16);
+        location[-1] = twoWordOp5i6Imm4Reg4EncodedImmSecond((location[-1] >> 8) & 0xf, hi16);
+
+        ExecutableAllocator::cacheFlush(location - 4, 4 * sizeof(uint16_t));
+    }
+
+    static void setPointer(void* code, void* value)
+    {
+        setInt32(code, reinterpret_cast<uint32_t>(value));
+    }
+
+    static bool isB(void* address)
+    {
+        uint16_t* instruction = static_cast<uint16_t*>(address);
+        return ((instruction[0] & 0xf800) == OP_B_T4a) && ((instruction[1] & 0xd000) == OP_B_T4b);
+    }
+
+    static bool isBX(void* address)
+    {
+        uint16_t* instruction = static_cast<uint16_t*>(address);
+        return (instruction[0] & 0xff87) == OP_BX;
+    }
+
+    static bool isMOV_imm_T3(void* address)
+    {
+        uint16_t* instruction = static_cast<uint16_t*>(address);
+        return ((instruction[0] & 0xFBF0) == OP_MOV_imm_T3) && ((instruction[1] & 0x8000) == 0);
+    }
+
+    static bool isMOVT(void* address)
+    {
+        uint16_t* instruction = static_cast<uint16_t*>(address);
+        return ((instruction[0] & 0xFBF0) == OP_MOVT) && ((instruction[1] & 0x8000) == 0);
+    }
+
+    static bool isNOP_T1(void* address)
+    {
+        uint16_t* instruction = static_cast<uint16_t*>(address);
+        return instruction[0] == OP_NOP_T1;
+    }
+
+    static bool isNOP_T2(void* address)
+    {
+        uint16_t* instruction = static_cast<uint16_t*>(address);
+        return (instruction[0] == OP_NOP_T2a) && (instruction[1] == OP_NOP_T2b);
+    }
+
+    static void linkJumpAbsolute(uint16_t* instruction, void* target)
+    {
+        // FIMXE: this should be up in the MacroAssembler layer. :-(
+        const uint16_t JUMP_TEMPORARY_REGISTER = ARMRegisters::ip;
+
+        ASSERT(!(reinterpret_cast<intptr_t>(instruction) & 1));
+        ASSERT(!(reinterpret_cast<intptr_t>(target) & 1));
+
+        ASSERT( (isMOV_imm_T3(instruction - 5) && isMOVT(instruction - 3) && isBX(instruction - 1))
+            || (isNOP_T1(instruction - 5) && isNOP_T2(instruction - 4) && isB(instruction - 2)) );
+
+        intptr_t relative = reinterpret_cast<intptr_t>(target) - (reinterpret_cast<intptr_t>(instruction));
+
+        // From Cortex-A8 errata:
+        // If the 32-bit Thumb-2 branch instruction spans two 4KiB regions and
+        // the target of the branch falls within the first region it is
+        // possible for the processor to incorrectly determine the branch
+        // instruction, and it is also possible in some cases for the processor
+        // to enter a deadlock state.
+        // The instruction is spanning two pages if it ends at an address ending 0x002
+        bool spansTwo4K = ((reinterpret_cast<intptr_t>(instruction) & 0xfff) == 0x002);
+        // The target is in the first page if the jump branch back by [3..0x1002] bytes
+        bool targetInFirstPage = (relative >= -0x1002) && (relative < -2);
+        bool wouldTriggerA8Errata = spansTwo4K && targetInFirstPage;
+
+        if (((relative << 7) >> 7) == relative && !wouldTriggerA8Errata) {
+            // ARM encoding for the top two bits below the sign bit is 'peculiar'.
+            if (relative >= 0)
+                relative ^= 0xC00000;
+
+            // All branch offsets should be an even distance.
+            ASSERT(!(relative & 1));
+            // There may be a better way to fix this, but right now put the NOPs first, since in the
+            // case of an conditional branch this will be coming after an ITTT predicating *three*
+            // instructions!  Looking backwards to modify the ITTT to an IT is not easy, due to
+            // variable wdith encoding - the previous instruction might *look* like an ITTT but
+            // actually be the second half of a 2-word op.
+            instruction[-5] = OP_NOP_T1;
+            instruction[-4] = OP_NOP_T2a;
+            instruction[-3] = OP_NOP_T2b;
+            instruction[-2] = OP_B_T4a | ((relative & 0x1000000) >> 14) | ((relative & 0x3ff000) >> 12);
+            instruction[-1] = OP_B_T4b | ((relative & 0x800000) >> 10) | ((relative & 0x400000) >> 11) | ((relative & 0xffe) >> 1);
+        } else {
+            ARMThumbImmediate lo16 = ARMThumbImmediate::makeUInt16(static_cast<uint16_t>(reinterpret_cast<uint32_t>(target) + 1));
+            ARMThumbImmediate hi16 = ARMThumbImmediate::makeUInt16(static_cast<uint16_t>(reinterpret_cast<uint32_t>(target) >> 16));
+            instruction[-5] = twoWordOp5i6Imm4Reg4EncodedImmFirst(OP_MOV_imm_T3, lo16);
+            instruction[-4] = twoWordOp5i6Imm4Reg4EncodedImmSecond(JUMP_TEMPORARY_REGISTER, lo16);
+            instruction[-3] = twoWordOp5i6Imm4Reg4EncodedImmFirst(OP_MOVT, hi16);
+            instruction[-2] = twoWordOp5i6Imm4Reg4EncodedImmSecond(JUMP_TEMPORARY_REGISTER, hi16);
+            instruction[-1] = OP_BX | (JUMP_TEMPORARY_REGISTER << 3);
+        }
+    }
+
+    static uint16_t twoWordOp5i6Imm4Reg4EncodedImmFirst(uint16_t op, ARMThumbImmediate imm)
+    {
+        return op | (imm.m_value.i << 10) | imm.m_value.imm4;
+    }
+    static uint16_t twoWordOp5i6Imm4Reg4EncodedImmSecond(uint16_t rd, ARMThumbImmediate imm)
+    {
+        return (imm.m_value.imm3 << 12) | (rd << 8) | imm.m_value.imm8;
+    }
+
+    class ARMInstructionFormatter {
+    public:
+        void oneWordOp5Reg3Imm8(OpcodeID op, RegisterID rd, uint8_t imm)
+        {
+            m_buffer.putShort(op | (rd << 8) | imm);
+        }
+        
+        void oneWordOp5Imm5Reg3Reg3(OpcodeID op, uint8_t imm, RegisterID reg1, RegisterID reg2)
+        {
+            m_buffer.putShort(op | (imm << 6) | (reg1 << 3) | reg2);
+        }
+
+        void oneWordOp7Reg3Reg3Reg3(OpcodeID op, RegisterID reg1, RegisterID reg2, RegisterID reg3)
+        {
+            m_buffer.putShort(op | (reg1 << 6) | (reg2 << 3) | reg3);
+        }
+
+        void oneWordOp8Imm8(OpcodeID op, uint8_t imm)
+        {
+            m_buffer.putShort(op | imm);
+        }
+
+        void oneWordOp8RegReg143(OpcodeID op, RegisterID reg1, RegisterID reg2)
+        {
+            m_buffer.putShort(op | ((reg2 & 8) << 4) | (reg1 << 3) | (reg2 & 7));
+        }
+        void oneWordOp9Imm7(OpcodeID op, uint8_t imm)
+        {
+            m_buffer.putShort(op | imm);
+        }
+
+        void oneWordOp10Reg3Reg3(OpcodeID op, RegisterID reg1, RegisterID reg2)
+        {
+            m_buffer.putShort(op | (reg1 << 3) | reg2);
+        }
+
+        void twoWordOp12Reg4FourFours(OpcodeID1 op, RegisterID reg, FourFours ff)
+        {
+            m_buffer.putShort(op | reg);
+            m_buffer.putShort(ff.m_u.value);
+        }
+        
+        void twoWordOp16FourFours(OpcodeID1 op, FourFours ff)
+        {
+            m_buffer.putShort(op);
+            m_buffer.putShort(ff.m_u.value);
+        }
+        
+        void twoWordOp16Op16(OpcodeID1 op1, OpcodeID2 op2)
+        {
+            m_buffer.putShort(op1);
+            m_buffer.putShort(op2);
+        }
+
+        void twoWordOp5i6Imm4Reg4EncodedImm(OpcodeID1 op, int imm4, RegisterID rd, ARMThumbImmediate imm)
+        {
+            ARMThumbImmediate newImm = imm;
+            newImm.m_value.imm4 = imm4;
+
+            m_buffer.putShort(ARMv7Assembler::twoWordOp5i6Imm4Reg4EncodedImmFirst(op, newImm));
+            m_buffer.putShort(ARMv7Assembler::twoWordOp5i6Imm4Reg4EncodedImmSecond(rd, newImm));
+        }
+
+        void twoWordOp12Reg4Reg4Imm12(OpcodeID1 op, RegisterID reg1, RegisterID reg2, uint16_t imm)
+        {
+            m_buffer.putShort(op | reg1);
+            m_buffer.putShort((reg2 << 12) | imm);
+        }
+
+        // Formats up instructions of the pattern:
+        //    111111111B11aaaa:bbbb222SA2C2cccc
+        // Where 1s in the pattern come from op1, 2s in the pattern come from op2, S is the provided size bit.
+        // Operands provide 5 bit values of the form Aaaaa, Bbbbb, Ccccc.
+        void vfpOp(OpcodeID1 op1, OpcodeID2 op2, bool size, VFPOperand a, VFPOperand b, VFPOperand c)
+        {
+            ASSERT(!(op1 & 0x004f));
+            ASSERT(!(op2 & 0xf1af));
+            m_buffer.putShort(op1 | b.bits1() << 6 | a.bits4());
+            m_buffer.putShort(op2 | b.bits4() << 12 | size << 8 | a.bits1() << 7 | c.bits1() << 5 | c.bits4());
+        }
+
+        // Arm vfp addresses can be offset by a 9-bit ones-comp immediate, left shifted by 2.
+        // (i.e. +/-(0..255) 32-bit words)
+        void vfpMemOp(OpcodeID1 op1, OpcodeID2 op2, bool size, RegisterID rn, VFPOperand rd, int32_t imm)
+        {
+            bool up = true;
+            if (imm < 0) {
+                imm = -imm;
+                up = false;
+            }
+            
+            uint32_t offset = imm;
+            ASSERT(!(offset & ~0x3fc));
+            offset >>= 2;
+
+            m_buffer.putShort(op1 | (up << 7) | rd.bits1() << 6 | rn);
+            m_buffer.putShort(op2 | rd.bits4() << 12 | size << 8 | offset);
+        }
+
+        // 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:
+        AssemblerBuffer m_buffer;
+    } m_formatter;
+
+    Vector<LinkRecord> m_jumpsToLink;
+};
+
+} // namespace JSC
+
+#endif // ENABLE(ASSEMBLER) && CPU(ARM_THUMB2)
+
+#endif // ARMAssembler_h