/**
* Return true if this instruction is independent of the specified instruction. If instructions
* are independent, than one instruction can be moved before or after the other instruction
* without changing the semantics of the program.
*
* @param inst is the specified instruction
*/
public boolean independent(Instruction inst, RegisterSet registers) {
if (inst.defs(rs1, registers)) return false;
if (inst.uses(rd, registers)) return false;
if (!(inst instanceof SparcInstruction)) return true;
return independentCC((SparcInstruction) inst);
}
protected void peepholeBeforeRegisterAllocation(Instruction first) {
Instruction inst = first;
while (inst != null) {
Instruction next = inst.getNext();
int opcode = inst.getOpcode();
// Recognize patterns, if any, here.
inst = next;
}
}
/** Remove all the predicates which are not defined in the hyperblock. */
private BitVect removePredicates(PredicateBlock start) {
BitVect predicates = new BitVect();
Stack<Node> wl = new Stack<Node>();
// Determine all the predicates defined outside this hyperblock.
start.nextVisit();
start.setVisited();
wl.add(start);
while (!wl.isEmpty()) {
PredicateBlock block = (PredicateBlock) wl.pop();
block.pushOutEdges(wl);
for (Instruction inst = block.getFirstInstruction(); inst != null; inst = inst.getNext()) {
if (inst.isMarker()) {
continue;
}
if (inst.isBranch()) {
continue;
}
if (((TripsInstruction) inst).definesPredicate()) {
predicates.set(inst.getDestRegister());
}
}
}
// Remove the predicates.
start.nextVisit();
start.setVisited();
wl.add(start);
while (!wl.isEmpty()) {
PredicateBlock block = (PredicateBlock) wl.pop();
block.pushOutEdges(wl);
if (!block.isPredicated()) {
continue;
}
int rp = block.getPredicate();
if (predicates.get(rp)) {
continue;
}
block.removePredicates();
for (Instruction inst = block.getFirstInstruction(); inst != null; inst = inst.getNext()) {
inst.removePredicates();
}
}
return predicates;
}
/**
* Find a split point for a block with spills. <br>
* We know the hyperblock was legal before the insertion of spill code. Return the "deepest" split
* point in the predicate flow graph, or if there are no split points, the block with the most
* instructions.
*/
private PredicateBlock findSplitPointSpills(Hyperblock hb) {
Vector<PredicateBlock> wl = new Vector<PredicateBlock>();
PredicateBlock start = hb.getFirstBlock();
PredicateBlock last = hb.getLastBlock();
PredicateBlock biggest = null;
PredicateBlock splitPoint = null;
int biggestSize = 0;
if (start.numOutEdges() == 0) {
return start;
}
start.nextVisit();
start.setVisited();
wl.add(start);
// Find the block with the most "real" instructions.
// We do not include fanout, nulls, or spill code.
while (!wl.isEmpty()) {
int sl = wl.size();
for (int i = 0; i < sl; i++) {
PredicateBlock block = wl.get(i);
int size = 0;
for (Instruction inst = block.getFirstInstruction(); inst != null; inst = inst.getNext()) {
size++; // TODO? Should we use the real size of the instruction?
}
if (size >= biggestSize) {
if (block != last) {
biggestSize = size;
biggest = block;
}
}
if (block.isSplitPoint() && (block != start)) {
splitPoint = block;
}
}
wl = hb.getNextPFGLevel(wl);
}
return (splitPoint != null) ? splitPoint : biggest;
}
/**
* Return the location in the block to split. Use the last spill store point found as the location
* to split. If no spill store is found, use the last instruction that does not cause a violation.
* This method will throw an exception if not split location is found.
*/
private final Instruction findSplitLocation(Hyperblock hb, PredicateBlock block, int chunkSize) {
int cLSID = 0;
int cSize = 0;
Instruction splitLocation = null;
boolean foundSpillPoint = false;
BitVect mov3 = new BitVect();
Stack<Node> wl = new Stack<Node>();
IntMap<Integer> uses = new IntMap<Integer>(37);
IntMap<Vector<Integer>> targets = hb.computeTargets(wl, mov3);
for (Instruction inst = block.getFirstInstruction(); inst != null; inst = inst.getNext()) {
if (inst.isMarker()) {
continue;
}
if (inst.isLoad() || inst.isStore()) {
int id =
(inst.isLoad()
? ((LoadInstruction) inst).getLSQid()
: ((StoreInstruction) inst).getLSQid());
if (id > cLSID) {
cLSID = id;
}
}
cSize += block.estimateNumInstructions(inst);
cSize += block.estimateFanout(inst, targets, uses, mov3);
if ((cLSID >= Trips2Machine.maxLSQEntries) || (cSize >= chunkSize)) {
if (splitLocation == null) {
splitLocation = inst; // Possible when splitting because of spills.
}
assert (splitLocation != block.getLastInstruction())
: "How is the last instruction the split location?";
return splitLocation;
}
if (inst.isSpillStorePoint()) {
splitLocation = inst;
foundSpillPoint = true;
}
if (!foundSpillPoint) {
splitLocation = inst;
}
}
throw new scale.common.InternalError("Could not find a location to split the predicate block.");
}
/**
* Return true if this instruction is independent of the specified instruction. If instructions
* are independent, than one instruction can be moved before or after the other instruction
* without changing the semantics of the program.
*
* @param inst is the specified instruction
*/
public boolean independent(Instruction inst, RegisterSet registers) {
return !inst.defs(rb, registers);
}
/**
* Return true if this instruction is independent of the specified instruction. If instructions
* are independent, than one instruction can be moved before or after the other instruction
* without changing the semantics of the program.
*
* @param inst is the specified instruction
*/
public boolean independent(Instruction inst, RegisterSet registers) {
if (inst.uses(ra, registers)) {
return false;
}
return !inst.defs(rb, registers);
}