/**
* Remove unreachable code
*
* @param ir the IR to optimize
*/
private void removeUnreachableCode(IR ir) {
boolean removedCode = false;
BasicBlock entry = ir.cfg.entry();
ir.cfg.clearDFS();
entry.sortDFS();
for (BasicBlock node = entry; node != null; ) {
// save it now before removeFromCFGAndCodeOrder nulls it out!!!
BasicBlock nextNode = (BasicBlock) node.getNext();
if (!node.dfsVisited()) {
for (BasicBlockEnumeration e = node.getOut(); e.hasMoreElements(); ) {
BasicBlock target = e.next();
if (target != node && !target.isExit() && target.dfsVisited()) {
SSA.purgeBlockFromPHIs(node, target);
}
}
ir.cfg.removeFromCFGAndCodeOrder(node);
removedCode = true;
}
node = nextNode;
}
if (removedCode) {
ir.cfg.compactNodeNumbering();
ir.HIRInfo.dominatorTree = null;
ir.HIRInfo.dominatorsAreComputed = false;
}
}
/**
* Returns an enumeration of the "prev" nodes (either in or out) for the passed block depending on
* which way we are viewing the graph
*
* @param block the basic block of interest
*/
private BasicBlockEnumeration getPrevNodes(BasicBlock block) {
BasicBlockEnumeration bbEnum;
if (forward) {
bbEnum = block.getIn();
} else {
bbEnum = block.getOut();
}
return bbEnum;
}