// Test whether there are any phis in |header| which are newly optimizable, as a
// result of optimizations done inside the loop. This is not a sparse approach,
// but restarting is rare enough in practice. Termination is ensured by
// discarding the phi triggering the iteration.
bool
ValueNumberer::loopHasOptimizablePhi(MBasicBlock* header) const
{
// If the header is unreachable, don't bother re-optimizing it.
if (header->isMarked())
return false;
// Rescan the phis for any that can be simplified, since they may be reading
// values from backedges.
for (MPhiIterator iter(header->phisBegin()), end(header->phisEnd()); iter != end; ++iter) {
MPhi* phi = *iter;
MOZ_ASSERT(phi->hasUses(), "Missed an unused phi");
if (phi->operandIfRedundant() || hasLeader(phi, header))
return true; // Phi can be simplified.
}
return false;
}
