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JavaScriptCore-7601.1.46.3.tar.gz
[apple/javascriptcore.git] / assembler / ARMv7Assembler.h
index a8b55d182d669766041249f19d4d067276956cc9..1d731f98b6a0f9d051684f69b90ba6c4460f393c 100644 (file)
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
+ * Copyright (C) 2009, 2010, 2012, 2013, 2014 Apple Inc. All rights reserved.
  * Copyright (C) 2010 University of Szeged
  *
  * Redistribution and use in source and binary forms, with or without
@@ -30,6 +30,7 @@
 #if ENABLE(ASSEMBLER) && CPU(ARM_THUMB2)
 
 #include "AssemblerBuffer.h"
+#include <limits.h>
 #include <wtf/Assertions.h>
 #include <wtf/Vector.h>
 #include <stdint.h>
 namespace JSC {
 
 namespace ARMRegisters {
+
+    #define FOR_EACH_CPU_REGISTER(V) \
+        FOR_EACH_CPU_GPREGISTER(V) \
+        FOR_EACH_CPU_SPECIAL_REGISTER(V) \
+        FOR_EACH_CPU_FPREGISTER(V)
+
+    // The following are defined as pairs of the following value:
+    // 1. type of the storage needed to save the register value by the JIT probe.
+    // 2. name of the register.
+    #define FOR_EACH_CPU_GPREGISTER(V) \
+        V(void*, r0) \
+        V(void*, r1) \
+        V(void*, r2) \
+        V(void*, r3) \
+        V(void*, r4) \
+        V(void*, r5) \
+        V(void*, r6) \
+        V(void*, r7) \
+        V(void*, r8) \
+        V(void*, r9) \
+        V(void*, r10) \
+        V(void*, r11) \
+        V(void*, ip) \
+        V(void*, sp) \
+        V(void*, lr) \
+        V(void*, pc)
+
+    #define FOR_EACH_CPU_SPECIAL_REGISTER(V) \
+        V(void*, apsr) \
+        V(void*, fpscr) \
+
+    #define FOR_EACH_CPU_FPREGISTER(V) \
+        V(double, d0) \
+        V(double, d1) \
+        V(double, d2) \
+        V(double, d3) \
+        V(double, d4) \
+        V(double, d5) \
+        V(double, d6) \
+        V(double, d7) \
+        V(double, d8) \
+        V(double, d9) \
+        V(double, d10) \
+        V(double, d11) \
+        V(double, d12) \
+        V(double, d13) \
+        V(double, d14) \
+        V(double, d15) \
+        V(double, d16) \
+        V(double, d17) \
+        V(double, d18) \
+        V(double, d19) \
+        V(double, d20) \
+        V(double, d21) \
+        V(double, d22) \
+        V(double, d23) \
+        V(double, d24) \
+        V(double, d25) \
+        V(double, d26) \
+        V(double, d27) \
+        V(double, d28) \
+        V(double, d29) \
+        V(double, d30) \
+        V(double, d31)
+
     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,
+        #define DECLARE_REGISTER(_type, _regName) _regName,
+        FOR_EACH_CPU_GPREGISTER(DECLARE_REGISTER)
+        #undef DECLARE_REGISTER
+
+        fp = r7,   // frame pointer
+        sb = r9,   // static base
+        sl = r10,  // stack limit
+        r12 = ip,
+        r13 = sp,
+        r14 = lr,
+        r15 = pc
     } RegisterID;
 
     typedef enum {
@@ -92,38 +153,9 @@ namespace ARMRegisters {
     } 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,
+        #define DECLARE_REGISTER(_type, _regName) _regName,
+        FOR_EACH_CPU_FPREGISTER(DECLARE_REGISTER)
+        #undef DECLARE_REGISTER
     } FPDoubleRegisterID;
 
     typedef enum {
@@ -172,7 +204,8 @@ namespace ARMRegisters {
         ASSERT(!(reg & 1));
         return (FPDoubleRegisterID)(reg >> 1);
     }
-}
+
+} // namespace ARMRegisters
 
 class ARMv7Assembler;
 class ARMThumbImmediate {
@@ -418,25 +451,32 @@ public:
     typedef ARMRegisters::FPSingleRegisterID FPSingleRegisterID;
     typedef ARMRegisters::FPDoubleRegisterID FPDoubleRegisterID;
     typedef ARMRegisters::FPQuadRegisterID FPQuadRegisterID;
+    typedef FPDoubleRegisterID FPRegisterID;
+    
+    static RegisterID firstRegister() { return ARMRegisters::r0; }
+    static RegisterID lastRegister() { return ARMRegisters::r13; }
+    
+    static FPRegisterID firstFPRegister() { return ARMRegisters::d0; }
+    static FPRegisterID lastFPRegister() { return ARMRegisters::d31; }
 
     // (HS, LO, HI, LS) -> (AE, B, A, BE)
     // (VS, VC) -> (O, NO)
     typedef enum {
-        ConditionEQ,
-        ConditionNE,
-        ConditionHS, ConditionCS = ConditionHS,
-        ConditionLO, ConditionCC = ConditionLO,
-        ConditionMI,
-        ConditionPL,
-        ConditionVS,
-        ConditionVC,
-        ConditionHI,
-        ConditionLS,
-        ConditionGE,
-        ConditionLT,
-        ConditionGT,
-        ConditionLE,
-        ConditionAL,
+        ConditionEQ, // Zero / Equal.
+        ConditionNE, // Non-zero / Not equal.
+        ConditionHS, ConditionCS = ConditionHS, // Unsigned higher or same.
+        ConditionLO, ConditionCC = ConditionLO, // Unsigned lower.
+        ConditionMI, // Negative.
+        ConditionPL, // Positive or zero.
+        ConditionVS, // Overflowed.
+        ConditionVC, // Not overflowed.
+        ConditionHI, // Unsigned higher.
+        ConditionLS, // Unsigned lower or same.
+        ConditionGE, // Signed greater than or equal.
+        ConditionLT, // Signed less than.
+        ConditionGT, // Signed greater than.
+        ConditionLE, // Signed less than or equal.
+        ConditionAL, // Unconditional / Always execute.
         ConditionInvalid
     } Condition;
 
@@ -498,10 +538,18 @@ public:
         } data;
     };
 
+    ARMv7Assembler()
+        : m_indexOfLastWatchpoint(INT_MIN)
+        , m_indexOfTailOfLastWatchpoint(INT_MIN)
+    {
+    }
+
+    AssemblerBuffer& buffer() { return m_formatter.m_buffer; }
+
 private:
 
     // ARMv7, Appx-A.6.3
-    bool BadReg(RegisterID reg)
+    static bool BadReg(RegisterID reg)
     {
         return (reg == ARMRegisters::sp) || (reg == ARMRegisters::pc);
     }
@@ -561,6 +609,8 @@ private:
         OP_ADD_SP_imm_T1    = 0xA800,
         OP_ADD_SP_imm_T2    = 0xB000,
         OP_SUB_SP_imm_T1    = 0xB080,
+        OP_PUSH_T1          = 0xB400,
+        OP_POP_T1           = 0xBC00,
         OP_BKPT             = 0xBE00,
         OP_IT               = 0xBF00,
         OP_NOP_T1           = 0xBF00,
@@ -569,6 +619,8 @@ private:
     typedef enum {
         OP_B_T1         = 0xD000,
         OP_B_T2         = 0xE000,
+        OP_POP_T2       = 0xE8BD,
+        OP_PUSH_T2      = 0xE92D,
         OP_AND_reg_T2   = 0xEA00,
         OP_TST_reg_T2   = 0xEA10,
         OP_ORR_reg_T2   = 0xEA40,
@@ -629,6 +681,7 @@ private:
         OP_MOVT         = 0xF2C0,
         OP_UBFX_T1      = 0xF3C0,
         OP_NOP_T2a      = 0xF3AF,
+        OP_DMB_SY_T2a   = 0xF3BF,
         OP_STRB_imm_T3  = 0xF800,
         OP_STRB_reg_T2  = 0xF800,
         OP_LDRB_imm_T3  = 0xF810,
@@ -655,6 +708,10 @@ private:
         OP_ROR_reg_T2   = 0xFA60,
         OP_CLZ          = 0xFAB0,
         OP_SMULL_T1     = 0xFB80,
+#if HAVE(ARM_IDIV_INSTRUCTIONS)
+        OP_SDIV_T1      = 0xFB90,
+        OP_UDIV_T1      = 0xFBB0,
+#endif
     } OpcodeID1;
 
     typedef enum {
@@ -681,6 +738,7 @@ private:
         OP_VCVTSD_T1b   = 0x0A40,
         OP_VCVTDS_T1b   = 0x0A40,
         OP_NOP_T2b      = 0x8000,
+        OP_DMB_SY_T2b   = 0x8F5F,
         OP_B_T3b        = 0x8000,
         OP_B_T4b        = 0x9000,
     } OpcodeID2;
@@ -708,11 +766,11 @@ private:
     class ARMInstructionFormatter;
 
     // false means else!
-    bool ifThenElseConditionBit(Condition condition, bool isIf)
+    static bool ifThenElseConditionBit(Condition condition, bool isIf)
     {
         return isIf ? (condition & 1) : !(condition & 1);
     }
-    uint8_t ifThenElse(Condition condition, bool inst2if, bool inst3if, bool inst4if)
+    static uint8_t ifThenElse(Condition condition, bool inst2if, bool inst3if, bool inst4if)
     {
         int mask = (ifThenElseConditionBit(condition, inst2if) << 3)
             | (ifThenElseConditionBit(condition, inst3if) << 2)
@@ -721,7 +779,7 @@ private:
         ASSERT((condition != ConditionAL) || !(mask & (mask - 1)));
         return (condition << 4) | mask;
     }
-    uint8_t ifThenElse(Condition condition, bool inst2if, bool inst3if)
+    static uint8_t ifThenElse(Condition condition, bool inst2if, bool inst3if)
     {
         int mask = (ifThenElseConditionBit(condition, inst2if) << 3)
             | (ifThenElseConditionBit(condition, inst3if) << 2)
@@ -729,7 +787,7 @@ private:
         ASSERT((condition != ConditionAL) || !(mask & (mask - 1)));
         return (condition << 4) | mask;
     }
-    uint8_t ifThenElse(Condition condition, bool inst2if)
+    static uint8_t ifThenElse(Condition condition, bool inst2if)
     {
         int mask = (ifThenElseConditionBit(condition, inst2if) << 3)
             | 4;
@@ -737,7 +795,7 @@ private:
         return (condition << 4) | mask;
     }
 
-    uint8_t ifThenElse(Condition condition)
+    static uint8_t ifThenElse(Condition condition)
     {
         int mask = 8;
         return (condition << 4) | mask;
@@ -764,7 +822,7 @@ public:
         ASSERT(rn != ARMRegisters::pc);
         ASSERT(imm.isValid());
 
-        if (rn == ARMRegisters::sp) {
+        if (rn == ARMRegisters::sp && imm.isUInt16()) {
             ASSERT(!(imm.getUInt16() & 3));
             if (!(rd & 8) && imm.isUInt10()) {
                 m_formatter.oneWordOp5Reg3Imm8(OP_ADD_SP_imm_T1, rd, static_cast<uint8_t>(imm.getUInt10() >> 2));
@@ -803,6 +861,11 @@ public:
     // NOTE: In an IT block, add doesn't modify the flags register.
     ALWAYS_INLINE void add(RegisterID rd, RegisterID rn, RegisterID rm)
     {
+        if (rd == ARMRegisters::sp) {
+            mov(rd, rn);
+            rn = rd;
+        }
+
         if (rd == rn)
             m_formatter.oneWordOp8RegReg143(OP_ADD_reg_T2, rm, rd);
         else if (rd == rm)
@@ -1026,6 +1089,12 @@ public:
         else
             m_formatter.twoWordOp12Reg4Reg4Imm12(OP_LDR_imm_T3, rn, rt, imm.getUInt12());
     }
+    
+    ALWAYS_INLINE void ldrWide8BitImmediate(RegisterID rt, RegisterID rn, uint8_t immediate)
+    {
+        ASSERT(rn != ARMRegisters::pc);
+        m_formatter.twoWordOp12Reg4Reg4Imm12(OP_LDR_imm_T3, rn, rt, immediate);
+    }
 
     ALWAYS_INLINE void ldrCompact(RegisterID rt, RegisterID rn, ARMThumbImmediate imm)
     {
@@ -1086,9 +1155,10 @@ public:
     {
         ASSERT(rn != ARMRegisters::pc); // LDR (literal)
         ASSERT(imm.isUInt12());
+        ASSERT(!(imm.getUInt12() & 1));
 
         if (!((rt | rn) & 8) && imm.isUInt6())
-            m_formatter.oneWordOp5Imm5Reg3Reg3(OP_LDRH_imm_T1, imm.getUInt6() >> 2, rn, rt);
+            m_formatter.oneWordOp5Imm5Reg3Reg3(OP_LDRH_imm_T1, imm.getUInt6() >> 1, rn, rt);
         else
             m_formatter.twoWordOp12Reg4Reg4Imm12(OP_LDRH_imm_T2, rn, rt, imm.getUInt12());
     }
@@ -1249,6 +1319,33 @@ public:
         
         m_formatter.twoWordOp5i6Imm4Reg4EncodedImm(OP_MOV_imm_T3, imm.m_value.imm4, rd, imm);
     }
+    
+#if OS(LINUX)
+    static void revertJumpTo_movT3movtcmpT2(void* instructionStart, RegisterID left, RegisterID right, uintptr_t imm)
+    {
+        uint16_t* address = static_cast<uint16_t*>(instructionStart);
+        ARMThumbImmediate lo16 = ARMThumbImmediate::makeUInt16(static_cast<uint16_t>(imm));
+        ARMThumbImmediate hi16 = ARMThumbImmediate::makeUInt16(static_cast<uint16_t>(imm >> 16));
+        address[0] = twoWordOp5i6Imm4Reg4EncodedImmFirst(OP_MOV_imm_T3, lo16);
+        address[1] = twoWordOp5i6Imm4Reg4EncodedImmSecond(right, lo16);
+        address[2] = twoWordOp5i6Imm4Reg4EncodedImmFirst(OP_MOVT, hi16);
+        address[3] = twoWordOp5i6Imm4Reg4EncodedImmSecond(right, hi16);
+        address[4] = OP_CMP_reg_T2 | left;
+        cacheFlush(address, sizeof(uint16_t) * 5);
+    }
+#else
+    static void revertJumpTo_movT3(void* instructionStart, RegisterID rd, ARMThumbImmediate imm)
+    {
+        ASSERT(imm.isValid());
+        ASSERT(!imm.isEncodedImm());
+        ASSERT(!BadReg(rd));
+        
+        uint16_t* address = static_cast<uint16_t*>(instructionStart);
+        address[0] = twoWordOp5i6Imm4Reg4EncodedImmFirst(OP_MOV_imm_T3, imm);
+        address[1] = twoWordOp5i6Imm4Reg4EncodedImmSecond(rd, imm);
+        cacheFlush(address, sizeof(uint16_t) * 2);
+    }
+#endif
 
     ALWAYS_INLINE void mov(RegisterID rd, ARMThumbImmediate imm)
     {
@@ -1364,6 +1461,56 @@ public:
         m_formatter.twoWordOp12Reg4FourFours(OP_ROR_reg_T2, rn, FourFours(0xf, rd, 0, rm));
     }
 
+    ALWAYS_INLINE void pop(RegisterID dest)
+    {
+        if (dest < ARMRegisters::r8)
+            m_formatter.oneWordOp7Imm9(OP_POP_T1, 1 << dest);
+        else {
+            // Load postindexed with writeback.
+            ldr(dest, ARMRegisters::sp, sizeof(void*), false, true);
+        }
+    }
+
+    ALWAYS_INLINE void pop(uint32_t registerList)
+    {
+        ASSERT(WTF::bitCount(registerList) > 1);
+        ASSERT(!((1 << ARMRegisters::pc) & registerList) || !((1 << ARMRegisters::lr) & registerList));
+        ASSERT(!((1 << ARMRegisters::sp) & registerList));
+        m_formatter.twoWordOp16Imm16(OP_POP_T2, registerList);
+    }
+
+    ALWAYS_INLINE void push(RegisterID src)
+    {
+        if (src < ARMRegisters::r8)
+            m_formatter.oneWordOp7Imm9(OP_PUSH_T1, 1 << src);
+        else if (src == ARMRegisters::lr)
+            m_formatter.oneWordOp7Imm9(OP_PUSH_T1, 0x100);
+        else {
+            // Store preindexed with writeback.
+            str(src, ARMRegisters::sp, -sizeof(void*), true, true);
+        }
+    }
+
+    ALWAYS_INLINE void push(uint32_t registerList)
+    {
+        ASSERT(WTF::bitCount(registerList) > 1);
+        ASSERT(!((1 << ARMRegisters::pc) & registerList));
+        ASSERT(!((1 << ARMRegisters::sp) & registerList));
+        m_formatter.twoWordOp16Imm16(OP_PUSH_T2, registerList);
+    }
+
+#if HAVE(ARM_IDIV_INSTRUCTIONS)
+    template<int datasize>
+    ALWAYS_INLINE void sdiv(RegisterID rd, RegisterID rn, RegisterID rm)
+    {
+        static_assert(datasize == 32, "sdiv datasize must be 32 for armv7s");        
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rn));
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_SDIV_T1, rn, FourFours(0xf, rd, 0xf, rm));
+    }
+#endif
+
     ALWAYS_INLINE void smull(RegisterID rdLo, RegisterID rdHi, RegisterID rn, RegisterID rm)
     {
         ASSERT(!BadReg(rdLo));
@@ -1501,8 +1648,8 @@ public:
         ASSERT(rn != ARMRegisters::pc);
         ASSERT(imm.isUInt12());
         
-        if (!((rt | rn) & 8) && imm.isUInt7())
-            m_formatter.oneWordOp5Imm5Reg3Reg3(OP_STRH_imm_T1, imm.getUInt7() >> 2, rn, rt);
+        if (!((rt | rn) & 8) && imm.isUInt6())
+            m_formatter.oneWordOp5Imm5Reg3Reg3(OP_STRH_imm_T1, imm.getUInt6() >> 1, rn, rt);
         else
             m_formatter.twoWordOp12Reg4Reg4Imm12(OP_STRH_imm_T2, rn, rt, imm.getUInt12());
     }
@@ -1700,6 +1847,16 @@ public:
         m_formatter.twoWordOp12Reg40Imm3Reg4Imm20Imm5(OP_UBFX_T1, rd, rn, (lsb & 0x1c) << 10, (lsb & 0x3) << 6, (width - 1) & 0x1f);
     }
 
+#if HAVE(ARM_IDIV_INSTRUCTIONS)
+    ALWAYS_INLINE void udiv(RegisterID rd, RegisterID rn, RegisterID rm)
+    {
+        ASSERT(!BadReg(rd));
+        ASSERT(!BadReg(rn));
+        ASSERT(!BadReg(rm));
+        m_formatter.twoWordOp12Reg4FourFours(OP_UDIV_T1, rn, FourFours(0xf, rd, 0xf, rm));
+    }
+#endif
+
     void vadd(FPDoubleRegisterID rd, FPDoubleRegisterID rn, FPDoubleRegisterID rm)
     {
         m_formatter.vfpOp(OP_VADD_T2, OP_VADD_T2b, true, rn, rd, rm);
@@ -1835,10 +1992,43 @@ public:
         m_formatter.oneWordOp8Imm8(OP_NOP_T1, 0);
     }
 
-    AssemblerLabel label()
+    void nopw()
+    {
+        m_formatter.twoWordOp16Op16(OP_NOP_T2a, OP_NOP_T2b);
+    }
+    
+    void dmbSY()
+    {
+        m_formatter.twoWordOp16Op16(OP_DMB_SY_T2a, OP_DMB_SY_T2b);
+    }
+
+    AssemblerLabel labelIgnoringWatchpoints()
     {
         return m_formatter.label();
     }
+
+    AssemblerLabel labelForWatchpoint()
+    {
+        AssemblerLabel result = m_formatter.label();
+        if (static_cast<int>(result.m_offset) != m_indexOfLastWatchpoint)
+            result = label();
+        m_indexOfLastWatchpoint = result.m_offset;
+        m_indexOfTailOfLastWatchpoint = result.m_offset + maxJumpReplacementSize();
+        return result;
+    }
+
+    AssemblerLabel label()
+    {
+        AssemblerLabel result = m_formatter.label();
+        while (UNLIKELY(static_cast<int>(result.m_offset) < m_indexOfTailOfLastWatchpoint)) {
+            if (UNLIKELY(static_cast<int>(result.m_offset) + 4 <= m_indexOfTailOfLastWatchpoint))
+                nopw();
+            else
+                nop();
+            result = m_formatter.label();
+        }
+        return result;
+    }
     
     AssemblerLabel align(int alignment)
     {
@@ -1859,14 +2049,7 @@ public:
         return b.m_offset - a.m_offset;
     }
 
-    int executableOffsetFor(int location)
-    {
-        if (!location)
-            return 0;
-        return static_cast<int32_t*>(m_formatter.data())[location / sizeof(int32_t) - 1];
-    }
-    
-    int jumpSizeDelta(JumpType jumpType, JumpLinkType jumpLinkType) { return JUMP_ENUM_SIZE(jumpType) - JUMP_ENUM_SIZE(jumpLinkType); }
+    static int jumpSizeDelta(JumpType jumpType, JumpLinkType jumpLinkType) { return JUMP_ENUM_SIZE(jumpType) - JUMP_ENUM_SIZE(jumpLinkType); }
     
     // Assembler admin methods:
 
@@ -1875,7 +2058,7 @@ public:
         return a.from() < b.from();
     }
 
-    bool canCompact(JumpType jumpType)
+    static bool canCompact(JumpType jumpType)
     {
         // The following cannot be compacted:
         //   JumpFixed: represents custom jump sequence
@@ -1884,7 +2067,7 @@ public:
         return (jumpType == JumpNoCondition) || (jumpType == JumpCondition);
     }
     
-    JumpLinkType computeJumpType(JumpType jumpType, const uint8_t* from, const uint8_t* to)
+    static JumpLinkType computeJumpType(JumpType jumpType, const uint8_t* from, const uint8_t* to)
     {
         if (jumpType == JumpFixed)
             return LinkInvalid;
@@ -1896,7 +2079,6 @@ public:
             return LinkConditionalBX;
         
         const int paddingSize = JUMP_ENUM_SIZE(jumpType);
-        bool mayTriggerErrata = false;
         
         if (jumpType == JumpCondition) {
             // 2-byte conditional T1
@@ -1905,17 +2087,13 @@ public:
                 return LinkJumpT1;
             // 4-byte conditional T3
             const uint16_t* jumpT3Location = reinterpret_cast_ptr<const uint16_t*>(from - (paddingSize - JUMP_ENUM_SIZE(LinkJumpT3)));
-            if (canBeJumpT3(jumpT3Location, to, mayTriggerErrata)) {
-                if (!mayTriggerErrata)
-                    return LinkJumpT3;
-            }
+            if (canBeJumpT3(jumpT3Location, to))
+                return LinkJumpT3;
             // 4-byte conditional T4 with IT
             const uint16_t* conditionalJumpT4Location = 
             reinterpret_cast_ptr<const uint16_t*>(from - (paddingSize - JUMP_ENUM_SIZE(LinkConditionalJumpT4)));
-            if (canBeJumpT4(conditionalJumpT4Location, to, mayTriggerErrata)) {
-                if (!mayTriggerErrata)
-                    return LinkConditionalJumpT4;
-            }
+            if (canBeJumpT4(conditionalJumpT4Location, to))
+                return LinkConditionalJumpT4;
         } else {
             // 2-byte unconditional T2
             const uint16_t* jumpT2Location = reinterpret_cast_ptr<const uint16_t*>(from - (paddingSize - JUMP_ENUM_SIZE(LinkJumpT2)));
@@ -1923,10 +2101,8 @@ public:
                 return LinkJumpT2;
             // 4-byte unconditional T4
             const uint16_t* jumpT4Location = reinterpret_cast_ptr<const uint16_t*>(from - (paddingSize - JUMP_ENUM_SIZE(LinkJumpT4)));
-            if (canBeJumpT4(jumpT4Location, to, mayTriggerErrata)) {
-                if (!mayTriggerErrata)
-                    return LinkJumpT4;
-            }
+            if (canBeJumpT4(jumpT4Location, to))
+                return LinkJumpT4;
             // use long jump sequence
             return LinkBX;
         }
@@ -1935,29 +2111,20 @@ public:
         return LinkConditionalBX;
     }
     
-    JumpLinkType computeJumpType(LinkRecord& record, const uint8_t* from, const uint8_t* to)
+    static JumpLinkType computeJumpType(LinkRecord& record, const uint8_t* from, const uint8_t* to)
     {
         JumpLinkType linkType = computeJumpType(record.type(), from, to);
         record.setLinkType(linkType);
         return linkType;
     }
     
-    void recordLinkOffsets(int32_t regionStart, int32_t regionEnd, int32_t offset)
-    {
-        int32_t ptr = regionStart / sizeof(int32_t);
-        const int32_t end = regionEnd / sizeof(int32_t);
-        int32_t* offsets = static_cast<int32_t*>(m_formatter.data());
-        while (ptr < end)
-            offsets[ptr++] = offset;
-    }
-    
-    Vector<LinkRecord>& jumpsToLink()
+    Vector<LinkRecord, 0, UnsafeVectorOverflow>& jumpsToLink()
     {
         std::sort(m_jumpsToLink.begin(), m_jumpsToLink.end(), linkRecordSourceComparator);
         return m_jumpsToLink;
     }
 
-    void ALWAYS_INLINE link(LinkRecord& record, uint8_t* from, uint8_t* to)
+    static void ALWAYS_INLINE link(LinkRecord& record, uint8_t* from, uint8_t* to)
     {
         switch (record.linkType()) {
         case LinkJumpT1:
@@ -1982,7 +2149,7 @@ public:
             linkBX(reinterpret_cast_ptr<uint16_t*>(from), to);
             break;
         default:
-            ASSERT_NOT_REACHED();
+            RELEASE_ASSERT_NOT_REACHED();
             break;
         }
     }
@@ -2023,14 +2190,13 @@ public:
     {
         ASSERT(!(reinterpret_cast<intptr_t>(code) & 1));
         ASSERT(from.isSet());
-        ASSERT(reinterpret_cast<intptr_t>(to) & 1);
 
-        setPointer(reinterpret_cast<uint16_t*>(reinterpret_cast<intptr_t>(code) + from.m_offset) - 1, to);
+        setPointer(reinterpret_cast<uint16_t*>(reinterpret_cast<intptr_t>(code) + from.m_offset) - 1, to, false);
     }
 
     static void linkPointer(void* code, AssemblerLabel where, void* value)
     {
-        setPointer(reinterpret_cast<char*>(code) + where.m_offset, value);
+        setPointer(reinterpret_cast<char*>(code) + where.m_offset, value, false);
     }
 
     static void relinkJump(void* from, void* to)
@@ -2046,9 +2212,8 @@ public:
     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);
+        setPointer(reinterpret_cast<uint16_t*>(from) - 1, to, true);
     }
     
     static void* readCallTarget(void* from)
@@ -2060,35 +2225,117 @@ public:
     {
         ASSERT(!(reinterpret_cast<intptr_t>(where) & 1));
         
-        setInt32(where, value);
+        setInt32(where, value, true);
     }
     
-    static void repatchCompact(void* where, int32_t value)
+    static void repatchCompact(void* where, int32_t offset)
     {
-        ASSERT(value >= 0);
-        ASSERT(ARMThumbImmediate::makeUInt12(value).isUInt7());
-        setUInt7ForLoad(where, ARMThumbImmediate::makeUInt12(value));
+        ASSERT(offset >= -255 && offset <= 255);
+
+        bool add = true;
+        if (offset < 0) {
+            add = false;
+            offset = -offset;
+        }
+        
+        offset |= (add << 9);
+        offset |= (1 << 10);
+        offset |= (1 << 11);
+
+        uint16_t* location = reinterpret_cast<uint16_t*>(where);
+        location[1] &= ~((1 << 12) - 1);
+        location[1] |= offset;
+        cacheFlush(location, sizeof(uint16_t) * 2);
     }
 
     static void repatchPointer(void* where, void* value)
     {
         ASSERT(!(reinterpret_cast<intptr_t>(where) & 1));
         
-        setPointer(where, value);
+        setPointer(where, value, true);
     }
 
     static void* readPointer(void* where)
     {
         return reinterpret_cast<void*>(readInt32(where));
     }
+    
+    static void replaceWithJump(void* instructionStart, void* to)
+    {
+        ASSERT(!(bitwise_cast<uintptr_t>(instructionStart) & 1));
+        ASSERT(!(bitwise_cast<uintptr_t>(to) & 1));
+
+#if OS(LINUX)
+        if (canBeJumpT4(reinterpret_cast<uint16_t*>(instructionStart), to)) {
+            uint16_t* ptr = reinterpret_cast<uint16_t*>(instructionStart) + 2;
+            linkJumpT4(ptr, to);
+            cacheFlush(ptr - 2, sizeof(uint16_t) * 2);
+        } else {
+            uint16_t* ptr = reinterpret_cast<uint16_t*>(instructionStart) + 5;
+            linkBX(ptr, to);
+            cacheFlush(ptr - 5, sizeof(uint16_t) * 5);
+        }
+#else
+        uint16_t* ptr = reinterpret_cast<uint16_t*>(instructionStart) + 2;
+        linkJumpT4(ptr, to);
+        cacheFlush(ptr - 2, sizeof(uint16_t) * 2);
+#endif
+    }
+    
+    static ptrdiff_t maxJumpReplacementSize()
+    {
+#if OS(LINUX)
+        return 10;
+#else
+        return 4;
+#endif
+    }
+    
+    static void replaceWithLoad(void* instructionStart)
+    {
+        ASSERT(!(bitwise_cast<uintptr_t>(instructionStart) & 1));
+        uint16_t* ptr = reinterpret_cast<uint16_t*>(instructionStart);
+        switch (ptr[0] & 0xFFF0) {
+        case OP_LDR_imm_T3:
+            break;
+        case OP_ADD_imm_T3:
+            ASSERT(!(ptr[1] & 0xF000));
+            ptr[0] &= 0x000F;
+            ptr[0] |= OP_LDR_imm_T3;
+            ptr[1] |= (ptr[1] & 0x0F00) << 4;
+            ptr[1] &= 0xF0FF;
+            cacheFlush(ptr, sizeof(uint16_t) * 2);
+            break;
+        default:
+            RELEASE_ASSERT_NOT_REACHED();
+        }
+    }
+
+    static void replaceWithAddressComputation(void* instructionStart)
+    {
+        ASSERT(!(bitwise_cast<uintptr_t>(instructionStart) & 1));
+        uint16_t* ptr = reinterpret_cast<uint16_t*>(instructionStart);
+        switch (ptr[0] & 0xFFF0) {
+        case OP_LDR_imm_T3:
+            ASSERT(!(ptr[1] & 0x0F00));
+            ptr[0] &= 0x000F;
+            ptr[0] |= OP_ADD_imm_T3;
+            ptr[1] |= (ptr[1] & 0xF000) >> 4;
+            ptr[1] &= 0x0FFF;
+            cacheFlush(ptr, sizeof(uint16_t) * 2);
+            break;
+        case OP_ADD_imm_T3:
+            break;
+        default:
+            RELEASE_ASSERT_NOT_REACHED();
+        }
+    }
 
     unsigned debugOffset() { return m_formatter.debugOffset(); }
 
-    static void cacheFlush(void* code, size_t size)
+#if OS(LINUX)
+    static inline void linuxPageFlush(uintptr_t begin, uintptr_t end)
     {
-#if OS(IOS)
-        sys_cache_control(kCacheFunctionPrepareForExecution, code, size);
-#elif OS(LINUX)
         asm volatile(
             "push    {r7}\n"
             "mov     r0, %0\n"
@@ -2099,17 +2346,32 @@ public:
             "svc     0x0\n"
             "pop     {r7}\n"
             :
-            : "r" (code), "r" (reinterpret_cast<char*>(code) + size)
+            : "r" (begin), "r" (end)
             : "r0", "r1", "r2");
-#elif OS(WINCE)
-        CacheRangeFlush(code, size, CACHE_SYNC_ALL);
-#elif OS(QNX)
-#if !ENABLE(ASSEMBLER_WX_EXCLUSIVE)
-        msync(code, size, MS_INVALIDATE_ICACHE);
-#else
-        UNUSED_PARAM(code);
-        UNUSED_PARAM(size);
+    }
 #endif
+
+    static void cacheFlush(void* code, size_t size)
+    {
+#if OS(IOS)
+        sys_cache_control(kCacheFunctionPrepareForExecution, code, size);
+#elif OS(LINUX)
+        size_t page = pageSize();
+        uintptr_t current = reinterpret_cast<uintptr_t>(code);
+        uintptr_t end = current + size;
+        uintptr_t firstPageEnd = (current & ~(page - 1)) + page;
+
+        if (end <= firstPageEnd) {
+            linuxPageFlush(current, end);
+            return;
+        }
+
+        linuxPageFlush(current, firstPageEnd);
+
+        for (current = firstPageEnd; current + page < end; current += page)
+            linuxPageFlush(current, current + page);
+
+        linuxPageFlush(current, end);
 #else
 #error "The cacheFlush support is missing on this platform."
 #endif
@@ -2182,7 +2444,7 @@ private:
         return VFPOperand(op);
     }
 
-    static void setInt32(void* code, uint32_t value)
+    static void setInt32(void* code, uint32_t value, bool flush)
     {
         uint16_t* location = reinterpret_cast<uint16_t*>(code);
         ASSERT(isMOV_imm_T3(location - 4) && isMOVT(location - 2));
@@ -2194,7 +2456,8 @@ private:
         location[-2] = twoWordOp5i6Imm4Reg4EncodedImmFirst(OP_MOVT, hi16);
         location[-1] = twoWordOp5i6Imm4Reg4EncodedImmSecond((location[-1] >> 8) & 0xf, hi16);
 
-        cacheFlush(location - 4, 4 * sizeof(uint16_t));
+        if (flush)
+            cacheFlush(location - 4, 4 * sizeof(uint16_t));
     }
     
     static int32_t readInt32(void* code)
@@ -2225,9 +2488,9 @@ private:
         cacheFlush(location, sizeof(uint16_t));
     }
 
-    static void setPointer(void* code, void* value)
+    static void setPointer(void* code, void* value, bool flush)
     {
-        setInt32(code, reinterpret_cast<uint32_t>(value));
+        setInt32(code, reinterpret_cast<uint32_t>(value), flush);
     }
 
     static bool isB(void* address)
@@ -2292,49 +2555,25 @@ private:
         return ((relative << 20) >> 20) == relative;
     }
     
-    static bool canBeJumpT3(const uint16_t* instruction, const void* target, bool& mayTriggerErrata)
+    static bool canBeJumpT3(const uint16_t* instruction, const void* target)
     {
         ASSERT(!(reinterpret_cast<intptr_t>(instruction) & 1));
         ASSERT(!(reinterpret_cast<intptr_t>(target) & 1));
         
         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);
-        mayTriggerErrata = spansTwo4K;
-        // 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;
-        return ((relative << 11) >> 11) == relative && !wouldTriggerA8Errata;
+        return ((relative << 11) >> 11) == relative;
     }
     
-    static bool canBeJumpT4(const uint16_t* instruction, const void* target, bool& mayTriggerErrata)
+    static bool canBeJumpT4(const uint16_t* instruction, const void* target)
     {
         ASSERT(!(reinterpret_cast<intptr_t>(instruction) & 1));
         ASSERT(!(reinterpret_cast<intptr_t>(target) & 1));
         
         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);
-        mayTriggerErrata = spansTwo4K;
-        // 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;
-        return ((relative << 7) >> 7) == relative && !wouldTriggerA8Errata;
+        return ((relative << 7) >> 7) == relative;
     }
     
-    void linkJumpT1(Condition cond, uint16_t* instruction, void* target)
+    static void linkJumpT1(Condition cond, uint16_t* instruction, void* target)
     {
         // FIMXE: this should be up in the MacroAssembler layer. :-(        
         ASSERT(!(reinterpret_cast<intptr_t>(instruction) & 1));
@@ -2370,14 +2609,12 @@ private:
         instruction[-1] = OP_B_T2 | ((relative & 0xffe) >> 1);
     }
     
-    void linkJumpT3(Condition cond, uint16_t* instruction, void* target)
+    static void linkJumpT3(Condition cond, uint16_t* instruction, void* target)
     {
         // FIMXE: this should be up in the MacroAssembler layer. :-(
         ASSERT(!(reinterpret_cast<intptr_t>(instruction) & 1));
         ASSERT(!(reinterpret_cast<intptr_t>(target) & 1));
-        bool scratch;
-        UNUSED_PARAM(scratch);
-        ASSERT(canBeJumpT3(instruction, target, scratch));
+        ASSERT(canBeJumpT3(instruction, target));
         
         intptr_t relative = reinterpret_cast<intptr_t>(target) - (reinterpret_cast<intptr_t>(instruction));
         
@@ -2392,9 +2629,7 @@ private:
         // FIMXE: this should be up in the MacroAssembler layer. :-(        
         ASSERT(!(reinterpret_cast<intptr_t>(instruction) & 1));
         ASSERT(!(reinterpret_cast<intptr_t>(target) & 1));
-        bool scratch;
-        UNUSED_PARAM(scratch);
-        ASSERT(canBeJumpT4(instruction, target, scratch));
+        ASSERT(canBeJumpT4(instruction, target));
         
         intptr_t relative = reinterpret_cast<intptr_t>(target) - (reinterpret_cast<intptr_t>(instruction));
         // ARM encoding for the top two bits below the sign bit is 'peculiar'.
@@ -2407,7 +2642,7 @@ private:
         instruction[-1] = OP_B_T4b | ((relative & 0x800000) >> 10) | ((relative & 0x400000) >> 11) | ((relative & 0xffe) >> 1);
     }
     
-    void linkConditionalJumpT4(Condition cond, uint16_t* instruction, void* target)
+    static void linkConditionalJumpT4(Condition cond, uint16_t* instruction, void* target)
     {
         // FIMXE: this should be up in the MacroAssembler layer. :-(        
         ASSERT(!(reinterpret_cast<intptr_t>(instruction) & 1));
@@ -2433,7 +2668,7 @@ private:
         instruction[-1] = OP_BX | (JUMP_TEMPORARY_REGISTER << 3);
     }
     
-    void linkConditionalBX(Condition cond, uint16_t* instruction, void* target)
+    static void linkConditionalBX(Condition cond, uint16_t* instruction, void* target)
     {
         // FIMXE: this should be up in the MacroAssembler layer. :-(        
         ASSERT(!(reinterpret_cast<intptr_t>(instruction) & 1));
@@ -2452,8 +2687,7 @@ private:
         ASSERT((isMOV_imm_T3(instruction - 5) && isMOVT(instruction - 3) && isBX(instruction - 1))
                || (isNOP_T1(instruction - 5) && isNOP_T2(instruction - 4) && isB(instruction - 2)));
         
-        bool scratch;
-        if (canBeJumpT4(instruction, target, scratch)) {
+        if (canBeJumpT4(instruction, target)) {
             // 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
@@ -2514,6 +2748,11 @@ private:
             m_buffer.putShort(op | (reg1 << 6) | (reg2 << 3) | reg3);
         }
 
+        ALWAYS_INLINE void oneWordOp7Imm9(OpcodeID op, uint16_t imm)
+        {
+            m_buffer.putShort(op | imm);
+        }
+
         ALWAYS_INLINE void oneWordOp8Imm8(OpcodeID op, uint8_t imm)
         {
             m_buffer.putShort(op | imm);
@@ -2552,6 +2791,12 @@ private:
             m_buffer.putShort(op2);
         }
 
+        ALWAYS_INLINE void twoWordOp16Imm16(OpcodeID1 op1, uint16_t imm)
+        {
+            m_buffer.putShort(op1);
+            m_buffer.putShort(imm);
+        }
+        
         ALWAYS_INLINE void twoWordOp5i6Imm4Reg4EncodedImm(OpcodeID1 op, int imm4, RegisterID rd, ARMThumbImmediate imm)
         {
             ARMThumbImmediate newImm = imm;
@@ -2612,12 +2857,12 @@ private:
 
         unsigned debugOffset() { return m_buffer.debugOffset(); }
 
-    private:
         AssemblerBuffer m_buffer;
     } m_formatter;
 
-    Vector<LinkRecord> m_jumpsToLink;
-    Vector<int32_t> m_offsets;
+    Vector<LinkRecord, 0, UnsafeVectorOverflow> m_jumpsToLink;
+    int m_indexOfLastWatchpoint;
+    int m_indexOfTailOfLastWatchpoint;
 };
 
 } // namespace JSC