/**
* Build BURS trees for dependence graph <code>bb</code>, label the trees, and then generate MIR
* instructions based on the labeling.
*
* @param bb The dependence graph. XXX Is this correct?
*/
public void invoke(OPT_BasicBlock bb) {
OPT_BURS_STATE burs = new OPT_BURS_STATE(this);
for (OPT_InstructionEnumeration e = bb.forwardRealInstrEnumerator(); e.hasMoreElements(); ) {
OPT_Instruction s = e.next();
OPT_BURS_TreeNode tn = buildTree(s);
burs.label(tn);
burs.mark(tn, /* goalnt */ (byte) 1);
generateTree(tn, burs);
}
}
// Generate code for a single tree root.
private void generateTree(OPT_BURS_TreeNode k, OPT_BURS_STATE burs) {
OPT_BURS_TreeNode child1 = k.child1;
OPT_BURS_TreeNode child2 = k.child2;
if (child1 != null) {
if (child2 != null) {
// k has two children; use register labeling to
// determine order that minimizes register pressure
if (k.isSuperNodeRoot()) {
byte act = burs.action[k.rule(k.getNonTerminal())];
if ((act & burs.RIGHT_CHILD_FIRST) != 0) {
// rule selected forces order of evaluation
generateTree(child2, burs);
generateTree(child1, burs);
} else {
generateTree(child1, burs);
generateTree(child2, burs);
}
} else {
generateTree(child1, burs);
generateTree(child2, burs);
}
} else {
generateTree(child1, burs);
}
} else if (child2 != null) {
generateTree(child2, burs);
}
if (k.isSuperNodeRoot()) {
int nonterminal = k.getNonTerminal();
int rule = k.rule(nonterminal);
burs.code(k, nonterminal, rule);
if (DEBUG) VM.sysWrite(k + " " + OPT_BURS_Debug.string[rule] + "\n");
}
}