void BytecodeLivenessAnalysis::runLivenessFixpoint()
{
UnlinkedCodeBlock* unlinkedCodeBlock = m_codeBlock->unlinkedCodeBlock();
unsigned numberOfVariables = unlinkedCodeBlock->m_numCalleeLocals;
for (unsigned i = 0; i < m_basicBlocks.size(); i++) {
BytecodeBasicBlock* block = m_basicBlocks[i].get();
block->in().resize(numberOfVariables);
block->out().resize(numberOfVariables);
}
bool changed;
m_basicBlocks.last()->in().clearAll();
m_basicBlocks.last()->out().clearAll();
FastBitVector newOut;
newOut.resize(m_basicBlocks.last()->out().numBits());
do {
changed = false;
for (unsigned i = m_basicBlocks.size() - 1; i--;) {
BytecodeBasicBlock* block = m_basicBlocks[i].get();
newOut.clearAll();
for (unsigned j = 0; j < block->successors().size(); j++)
newOut.merge(block->successors()[j]->in());
bool outDidChange = block->out().setAndCheck(newOut);
computeLocalLivenessForBlock(m_codeBlock, block, m_basicBlocks);
changed |= outDidChange;
}
} while (changed);
}
static void computeLocalLivenessForBytecodeOffset(CodeBlock* codeBlock, BytecodeBasicBlock* block, Vector<RefPtr<BytecodeBasicBlock> >& basicBlocks, unsigned targetOffset, FastBitVector& result)
{
ASSERT(!block->isExitBlock());
ASSERT(!block->isEntryBlock());
FastBitVector out = block->out();
HandlerInfo* handler = 0;
FastBitVector uses;
FastBitVector defs;
uses.resize(out.numBits());
defs.resize(out.numBits());
for (int i = block->bytecodeOffsets().size() - 1; i >= 0; i--) {
unsigned bytecodeOffset = block->bytecodeOffsets()[i];
if (targetOffset > bytecodeOffset)
break;
uses.clearAll();
defs.clearAll();
computeUsesForBytecodeOffset(codeBlock, bytecodeOffset, uses);
computeDefsForBytecodeOffset(codeBlock, bytecodeOffset, defs);
out.exclude(defs);
out.merge(uses);
// If we have an exception handler, we want the live-in variables of the
// exception handler block to be included in the live-in of this particular bytecode.
if ((handler = codeBlock->handlerForBytecodeOffset(bytecodeOffset))) {
BytecodeBasicBlock* handlerBlock = findBasicBlockWithLeaderOffset(basicBlocks, handler->target);
ASSERT(handlerBlock);
out.merge(handlerBlock->in());
}
}
result.set(out);
}
