bytecode/PreciseJumpTargets.cpp

   1 /*
   2  * Copyright (C) 2013 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 #include "config.h"
  27 #include "PreciseJumpTargets.h"
  28
  29 #include "JSCInlines.h"
  30
  31 namespace JSC {
  32
  33 template <size_t vectorSize>
  34 static void getJumpTargetsForBytecodeOffset(CodeBlock* codeBlock, Interpreter* interpreter, Instruction* instructionsBegin, unsigned bytecodeOffset, Vector<unsigned, vectorSize>& out)
  35 {
  36     OpcodeID opcodeID = interpreter->getOpcodeID(instructionsBegin[bytecodeOffset].u.opcode);
  37     Instruction* current = instructionsBegin + bytecodeOffset;
  38     switch (opcodeID) {
  39     case op_jmp:
  40         out.append(bytecodeOffset + current[1].u.operand);
  41         break;
  42     case op_jtrue:
  43     case op_jfalse:
  44     case op_jeq_null:
  45     case op_jneq_null:
  46         out.append(bytecodeOffset + current[2].u.operand);
  47         break;
  48     case op_jneq_ptr:
  49     case op_jless:
  50     case op_jlesseq:
  51     case op_jgreater:
  52     case op_jgreatereq:
  53     case op_jnless:
  54     case op_jnlesseq:
  55     case op_jngreater:
  56     case op_jngreatereq:
  57         out.append(bytecodeOffset + current[3].u.operand);
  58         break;
  59     case op_switch_imm:
  60     case op_switch_char: {
  61         SimpleJumpTable& table = codeBlock->switchJumpTable(current[1].u.operand);
  62         for (unsigned i = table.branchOffsets.size(); i--;)
  63             out.append(bytecodeOffset + table.branchOffsets[i]);
  64         out.append(bytecodeOffset + current[2].u.operand);
  65         break;
  66     }
  67     case op_switch_string: {
  68         StringJumpTable& table = codeBlock->stringSwitchJumpTable(current[1].u.operand);
  69         StringJumpTable::StringOffsetTable::iterator iter = table.offsetTable.begin();
  70         StringJumpTable::StringOffsetTable::iterator end = table.offsetTable.end();
  71         for (; iter != end; ++iter)
  72             out.append(bytecodeOffset + iter->value.branchOffset);
  73         out.append(bytecodeOffset + current[2].u.operand);
  74         break;
  75     }
  76     case op_get_pnames:
  77         out.append(bytecodeOffset + current[5].u.operand);
  78         break;
  79     case op_next_pname:
  80         out.append(bytecodeOffset + current[6].u.operand);
  81         break;
  82     case op_check_has_instance:
  83         out.append(bytecodeOffset + current[4].u.operand);
  84         break;
  85     case op_loop_hint:
  86         out.append(bytecodeOffset);
  87         break;
  88     default:
  89         break;
  90     }
  91 }
  92
  93 void computePreciseJumpTargets(CodeBlock* codeBlock, Vector<unsigned, 32>& out)
  94 {
  95     ASSERT(out.isEmpty());
  96
  97     // We will derive a superset of the jump targets that the code block thinks it has.
  98     // So, if the code block claims there are none, then we are done.
  99     if (!codeBlock->numberOfJumpTargets())
 100         return;
 101
 102     for (unsigned i = codeBlock->numberOfExceptionHandlers(); i--;)
 103         out.append(codeBlock->exceptionHandler(i).target);
 104
 105     Interpreter* interpreter = codeBlock->vm()->interpreter;
 106     Instruction* instructionsBegin = codeBlock->instructions().begin();
 107     unsigned instructionCount = codeBlock->instructions().size();
 108     for (unsigned bytecodeOffset = 0; bytecodeOffset < instructionCount;) {
 109         OpcodeID opcodeID = interpreter->getOpcodeID(instructionsBegin[bytecodeOffset].u.opcode);
 110         getJumpTargetsForBytecodeOffset(codeBlock, interpreter, instructionsBegin, bytecodeOffset, out);
 111         bytecodeOffset += opcodeLengths[opcodeID];
 112     }
 113
 114     std::sort(out.begin(), out.end());
 115
 116     // We will have duplicates, and we must remove them.
 117     unsigned toIndex = 0;
 118     unsigned fromIndex = 0;
 119     unsigned lastValue = UINT_MAX;
 120     while (fromIndex < out.size()) {
 121         unsigned value = out[fromIndex++];
 122         if (value == lastValue)
 123             continue;
 124         out[toIndex++] = value;
 125         lastValue = value;
 126     }
 127     out.resize(toIndex);
 128 }
 129
 130 void findJumpTargetsForBytecodeOffset(CodeBlock* codeBlock, unsigned bytecodeOffset, Vector<unsigned, 1>& out)
 131 {
 132     Interpreter* interpreter = codeBlock->vm()->interpreter;
 133     Instruction* instructionsBegin = codeBlock->instructions().begin();
 134     getJumpTargetsForBytecodeOffset(codeBlock, interpreter, instructionsBegin, bytecodeOffset, out);
 135 }
 136
 137 } // namespace JSC
 138