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      1 /*
      2  * Copyright (C) 2009 Apple Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #ifndef CodeLocation_h
     27 #define CodeLocation_h
     28 
     29 #include <wtf/Platform.h>
     30 
     31 #include <MacroAssemblerCodeRef.h>
     32 
     33 #if ENABLE(ASSEMBLER)
     34 
     35 namespace JSC {
     36 
     37 class CodeLocationInstruction;
     38 class CodeLocationLabel;
     39 class CodeLocationJump;
     40 class CodeLocationCall;
     41 class CodeLocationNearCall;
     42 class CodeLocationDataLabel32;
     43 class CodeLocationDataLabelPtr;
     44 
     45 // The CodeLocation* types are all pretty much do-nothing wrappers around
     46 // CodePtr (or MacroAssemblerCodePtr, to give it its full name).  These
     47 // classes only exist to provide type-safety when linking and patching code.
     48 //
     49 // The one new piece of functionallity introduced by these classes is the
     50 // ability to create (or put another way, to re-discover) another CodeLocation
     51 // at an offset from one you already know.  When patching code to optimize it
     52 // we often want to patch a number of instructions that are short, fixed
     53 // offsets apart.  To reduce memory overhead we will only retain a pointer to
     54 // one of the instructions, and we will use the *AtOffset methods provided by
     55 // CodeLocationCommon to find the other points in the code to modify.
     56 class CodeLocationCommon : public MacroAssemblerCodePtr {
     57 public:
     58     CodeLocationInstruction instructionAtOffset(int offset);
     59     CodeLocationLabel labelAtOffset(int offset);
     60     CodeLocationJump jumpAtOffset(int offset);
     61     CodeLocationCall callAtOffset(int offset);
     62     CodeLocationNearCall nearCallAtOffset(int offset);
     63     CodeLocationDataLabelPtr dataLabelPtrAtOffset(int offset);
     64     CodeLocationDataLabel32 dataLabel32AtOffset(int offset);
     65 
     66 protected:
     67     CodeLocationCommon()
     68     {
     69     }
     70 
     71     CodeLocationCommon(MacroAssemblerCodePtr location)
     72         : MacroAssemblerCodePtr(location)
     73     {
     74     }
     75 };
     76 
     77 class CodeLocationInstruction : public CodeLocationCommon {
     78 public:
     79     CodeLocationInstruction() {}
     80     explicit CodeLocationInstruction(MacroAssemblerCodePtr location)
     81         : CodeLocationCommon(location) {}
     82     explicit CodeLocationInstruction(void* location)
     83         : CodeLocationCommon(MacroAssemblerCodePtr(location)) {}
     84 };
     85 
     86 class CodeLocationLabel : public CodeLocationCommon {
     87 public:
     88     CodeLocationLabel() {}
     89     explicit CodeLocationLabel(MacroAssemblerCodePtr location)
     90         : CodeLocationCommon(location) {}
     91     explicit CodeLocationLabel(void* location)
     92         : CodeLocationCommon(MacroAssemblerCodePtr(location)) {}
     93 };
     94 
     95 class CodeLocationJump : public CodeLocationCommon {
     96 public:
     97     CodeLocationJump() {}
     98     explicit CodeLocationJump(MacroAssemblerCodePtr location)
     99         : CodeLocationCommon(location) {}
    100     explicit CodeLocationJump(void* location)
    101         : CodeLocationCommon(MacroAssemblerCodePtr(location)) {}
    102 };
    103 
    104 class CodeLocationCall : public CodeLocationCommon {
    105 public:
    106     CodeLocationCall() {}
    107     explicit CodeLocationCall(MacroAssemblerCodePtr location)
    108         : CodeLocationCommon(location) {}
    109     explicit CodeLocationCall(void* location)
    110         : CodeLocationCommon(MacroAssemblerCodePtr(location)) {}
    111 };
    112 
    113 class CodeLocationNearCall : public CodeLocationCommon {
    114 public:
    115     CodeLocationNearCall() {}
    116     explicit CodeLocationNearCall(MacroAssemblerCodePtr location)
    117         : CodeLocationCommon(location) {}
    118     explicit CodeLocationNearCall(void* location)
    119         : CodeLocationCommon(MacroAssemblerCodePtr(location)) {}
    120 };
    121 
    122 class CodeLocationDataLabel32 : public CodeLocationCommon {
    123 public:
    124     CodeLocationDataLabel32() {}
    125     explicit CodeLocationDataLabel32(MacroAssemblerCodePtr location)
    126         : CodeLocationCommon(location) {}
    127     explicit CodeLocationDataLabel32(void* location)
    128         : CodeLocationCommon(MacroAssemblerCodePtr(location)) {}
    129 };
    130 
    131 class CodeLocationDataLabelPtr : public CodeLocationCommon {
    132 public:
    133     CodeLocationDataLabelPtr() {}
    134     explicit CodeLocationDataLabelPtr(MacroAssemblerCodePtr location)
    135         : CodeLocationCommon(location) {}
    136     explicit CodeLocationDataLabelPtr(void* location)
    137         : CodeLocationCommon(MacroAssemblerCodePtr(location)) {}
    138 };
    139 
    140 inline CodeLocationInstruction CodeLocationCommon::instructionAtOffset(int offset)
    141 {
    142     ASSERT_VALID_CODE_OFFSET(offset);
    143     return CodeLocationInstruction(reinterpret_cast<char*>(dataLocation()) + offset);
    144 }
    145 
    146 inline CodeLocationLabel CodeLocationCommon::labelAtOffset(int offset)
    147 {
    148     ASSERT_VALID_CODE_OFFSET(offset);
    149     return CodeLocationLabel(reinterpret_cast<char*>(dataLocation()) + offset);
    150 }
    151 
    152 inline CodeLocationJump CodeLocationCommon::jumpAtOffset(int offset)
    153 {
    154     ASSERT_VALID_CODE_OFFSET(offset);
    155     return CodeLocationJump(reinterpret_cast<char*>(dataLocation()) + offset);
    156 }
    157 
    158 inline CodeLocationCall CodeLocationCommon::callAtOffset(int offset)
    159 {
    160     ASSERT_VALID_CODE_OFFSET(offset);
    161     return CodeLocationCall(reinterpret_cast<char*>(dataLocation()) + offset);
    162 }
    163 
    164 inline CodeLocationNearCall CodeLocationCommon::nearCallAtOffset(int offset)
    165 {
    166     ASSERT_VALID_CODE_OFFSET(offset);
    167     return CodeLocationNearCall(reinterpret_cast<char*>(dataLocation()) + offset);
    168 }
    169 
    170 inline CodeLocationDataLabelPtr CodeLocationCommon::dataLabelPtrAtOffset(int offset)
    171 {
    172     ASSERT_VALID_CODE_OFFSET(offset);
    173     return CodeLocationDataLabelPtr(reinterpret_cast<char*>(dataLocation()) + offset);
    174 }
    175 
    176 inline CodeLocationDataLabel32 CodeLocationCommon::dataLabel32AtOffset(int offset)
    177 {
    178     ASSERT_VALID_CODE_OFFSET(offset);
    179     return CodeLocationDataLabel32(reinterpret_cast<char*>(dataLocation()) + offset);
    180 }
    181 
    182 } // namespace JSC
    183 
    184 #endif // ENABLE(ASSEMBLER)
    185 
    186 #endif // CodeLocation_h
    187