BytecodeRewriter.cpp [plain text]
#include "config.h"
#include "BytecodeRewriter.h"
#include "HeapInlines.h"
#include "PreciseJumpTargetsInlines.h"
#include <wtf/BubbleSort.h>
namespace JSC {
void BytecodeRewriter::applyModification()
{
for (size_t insertionIndex = m_insertions.size(); insertionIndex--;) {
Insertion& insertion = m_insertions[insertionIndex];
if (insertion.type == Insertion::Type::Remove)
m_graph.instructions().remove(insertion.index.bytecodeOffset, insertion.length());
else {
if (insertion.includeBranch == IncludeBranch::Yes) {
int finalOffset = insertion.index.bytecodeOffset + calculateDifference(m_insertions.begin(), m_insertions.begin() + insertionIndex);
adjustJumpTargetsInFragment(finalOffset, insertion);
}
m_graph.instructions().insertVector(insertion.index.bytecodeOffset, insertion.instructions);
}
}
m_insertions.clear();
}
void BytecodeRewriter::execute()
{
WTF::bubbleSort(m_insertions.begin(), m_insertions.end(), [] (const Insertion& lhs, const Insertion& rhs) {
return lhs.index < rhs.index;
});
UnlinkedCodeBlock* codeBlock = m_graph.codeBlock();
codeBlock->applyModification(*this);
}
void BytecodeRewriter::adjustJumpTargetsInFragment(unsigned finalOffset, Insertion& insertion)
{
auto& fragment = insertion.instructions;
UnlinkedInstruction* instructionsBegin = fragment.data();
for (unsigned fragmentOffset = 0, fragmentCount = fragment.size(); fragmentOffset < fragmentCount;) {
UnlinkedInstruction& instruction = fragment[fragmentOffset];
OpcodeID opcodeID = instruction.u.opcode;
if (isBranch(opcodeID)) {
unsigned bytecodeOffset = finalOffset + fragmentOffset;
UnlinkedCodeBlock* codeBlock = m_graph.codeBlock();
extractStoredJumpTargetsForBytecodeOffset(codeBlock, instructionsBegin, fragmentOffset, [&](int32_t& label) {
int absoluteOffset = adjustAbsoluteOffset(label);
label = absoluteOffset - static_cast<int>(bytecodeOffset);
});
}
fragmentOffset += opcodeLength(opcodeID);
}
}
void BytecodeRewriter::insertImpl(InsertionPoint insertionPoint, IncludeBranch includeBranch, Vector<UnlinkedInstruction>&& fragment)
{
ASSERT(insertionPoint.position == Position::Before || insertionPoint.position == Position::After);
m_insertions.append(Insertion {
insertionPoint,
Insertion::Type::Insert,
includeBranch,
0,
WTFMove(fragment)
});
}
int BytecodeRewriter::adjustJumpTarget(InsertionPoint startPoint, InsertionPoint jumpTargetPoint)
{
if (startPoint < jumpTargetPoint) {
int jumpTarget = jumpTargetPoint.bytecodeOffset;
auto start = std::lower_bound(m_insertions.begin(), m_insertions.end(), startPoint, [&] (const Insertion& insertion, InsertionPoint startPoint) {
return insertion.index < startPoint;
});
if (start != m_insertions.end()) {
auto end = std::lower_bound(m_insertions.begin(), m_insertions.end(), jumpTargetPoint, [&] (const Insertion& insertion, InsertionPoint jumpTargetPoint) {
return insertion.index < jumpTargetPoint;
});
jumpTarget += calculateDifference(start, end);
}
return jumpTarget - startPoint.bytecodeOffset;
}
if (startPoint == jumpTargetPoint)
return 0;
return -adjustJumpTarget(jumpTargetPoint, startPoint);
}
}