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