bool
MBasicBlock::inherit(MBasicBlock *pred, uint32_t popped)
{
if (pred) {
stackPosition_ = pred->stackPosition_;
JS_ASSERT(stackPosition_ >= popped);
stackPosition_ -= popped;
if (kind_ != PENDING_LOOP_HEADER)
copySlots(pred);
} else if (pc()) {
uint32_t stackDepth = info().script()->analysis()->getCode(pc()).stackDepth;
stackPosition_ = info().firstStackSlot() + stackDepth;
JS_ASSERT(stackPosition_ >= popped);
stackPosition_ -= popped;
} else {
stackPosition_ = info().firstStackSlot();
}
JS_ASSERT(info_.nslots() >= stackPosition_);
JS_ASSERT(!entryResumePoint_);
if (pc()) {
// Propagate the caller resume point from the inherited block.
MResumePoint *callerResumePoint = pred ? pred->callerResumePoint() : NULL;
// Create a resume point using our initial stack state.
entryResumePoint_ = new MResumePoint(this, pc(), callerResumePoint, MResumePoint::ResumeAt);
if (!entryResumePoint_->init())
return false;
}
if (pred) {
if (!predecessors_.append(pred))
return false;
if (kind_ == PENDING_LOOP_HEADER) {
for (size_t i = 0; i < stackDepth(); i++) {
MPhi *phi = MPhi::New(i);
if (!phi->initLength(1))
return false;
phi->setOperand(0, pred->getSlot(i));
addPhi(phi);
setSlot(i, phi);
if (entryResumePoint())
entryResumePoint()->setOperand(i, phi);
}
} else if (entryResumePoint()) {
for (size_t i = 0; i < stackDepth(); i++)
entryResumePoint()->setOperand(i, getSlot(i));
}
}
return true;
}
bool
MBasicBlock::addPredecessorPopN(MBasicBlock *pred, uint32_t popped)
{
JS_ASSERT(pred);
JS_ASSERT(predecessors_.length() > 0);
// Predecessors must be finished, and at the correct stack depth.
JS_ASSERT(pred->lastIns_);
JS_ASSERT(pred->stackPosition_ == stackPosition_ + popped);
for (uint32_t i = 0; i < stackPosition_; i++) {
MDefinition *mine = getSlot(i);
MDefinition *other = pred->getSlot(i);
if (mine != other) {
// If the current instruction is a phi, and it was created in this
// basic block, then we have already placed this phi and should
// instead append to its operands.
if (mine->isPhi() && mine->block() == this) {
JS_ASSERT(predecessors_.length());
if (!mine->toPhi()->addInputSlow(other))
return false;
} else {
// Otherwise, create a new phi node.
MPhi *phi = MPhi::New(i);
addPhi(phi);
// Prime the phi for each predecessor, so input(x) comes from
// predecessor(x).
if (!phi->initLength(predecessors_.length() + 1))
return false;
for (size_t j = 0; j < predecessors_.length(); j++) {
JS_ASSERT(predecessors_[j]->getSlot(i) == mine);
phi->setOperand(j, mine);
}
phi->setOperand(predecessors_.length(), other);
setSlot(i, phi);
if (entryResumePoint())
entryResumePoint()->replaceOperand(i, phi);
}
}
}
return predecessors_.append(pred);
}