/**
* Build a BURS Tree for each OPT_Instruction. Complete BURS trees by adding leaf nodes as needed,
* and creating tree edges by calling insertChild1() or insertChild2() This step is also where we
* introduce intermediate tree nodes for any LIR instruction that has > 2 "real" operands e.g., a
* CALL.
*
* @param s The instruction for which a tree must be built
*/
private OPT_BURS_TreeNode buildTree(OPT_Instruction s) {
OPT_BURS_TreeNode root = new OPT_BURS_TreeNode(new OPT_DepGraphNode(s));
OPT_BURS_TreeNode cur = root;
for (OPT_OperandEnumeration uses = s.getUses(); uses.hasMoreElements(); ) {
OPT_Operand op = uses.next();
if (op == null) continue;
op.clear();
// Set child = OPT_BURS_TreeNode for operand op
OPT_BURS_TreeNode child;
if (op instanceof OPT_RegisterOperand) {
if (op.asRegister().register.isValidation()) continue;
child = Register;
} else if (op instanceof OPT_IntConstantOperand) {
child = new OPT_BURS_IntConstantTreeNode(((OPT_IntConstantOperand) op).value);
} else if (op instanceof OPT_LongConstantOperand) {
child = LongConstant;
} else if (op instanceof OPT_AddressConstantOperand) {
child = AddressConstant;
} else if (op instanceof OPT_BranchOperand && s.isCall()) {
child = BranchTarget;
// -#if RVM_WITH_OSR
} else if (op instanceof OPT_InlinedOsrTypeInfoOperand && s.isYieldPoint()) {
child = NullTreeNode;
// -#endif
} else {
continue;
}
// Attach child as child of cur_parent in correct position
if (cur.child1 == null) {
cur.child1 = child;
} else if (cur.child2 == null) {
cur.child2 = child;
} else {
// Create auxiliary node so as to represent
// a instruction with arity > 2 in a binary tree.
OPT_BURS_TreeNode child1 = cur.child2;
OPT_BURS_TreeNode aux = new OPT_BURS_TreeNode(OTHER_OPERAND_opcode);
cur.child2 = aux;
cur = aux;
cur.child1 = child1;
cur.child2 = child;
}
}
// patch for calls & return
switch (s.getOpcode()) {
case CALL_opcode:
case SYSCALL_opcode:
// -#if RVM_WITH_OSR
case YIELDPOINT_OSR_opcode:
// -#endif
if (cur.child2 == null) cur.child2 = NullTreeNode;
// fall through
case RETURN_opcode:
if (cur.child1 == null) cur.child1 = NullTreeNode;
}
return root;
}