public String toString() {
StringBuffer buf = new StringBuffer("{RG ");
int len = refs.size();
if (len > 3) len = 3;
for (int i = 0; i < len; i++) {
if (i > 0) buf.append(',');
buf.append(refs.elementAt(i));
}
if (len < refs.size()) buf.append(", ...");
buf.append('}');
return buf.toString();
}
private Cost computeRefCostSum(LoopHeaderChord loop, Vector<RefGroup> refGroups) {
Cost lc = new Cost();
int l = refGroups.size();
for (int i = 0; i < l; i++) {
RefGroup rg = refGroups.elementAt(i);
SubscriptExpr se = rg.getRepresentative();
Cost cost = computeRefCost(loop, se);
if (cost == null) continue;
lc.add(cost);
}
return lc;
}
public void perform() {
if (trace) System.out.println("** LP " + scribble.getRoutineDecl().getName());
LoopHeaderChord lt = scribble.getLoopTree();
Vector<LoopHeaderChord> innerLoops = lt.getInnerLoops();
for (int li = 0; li < innerLoops.size(); li++) {
LoopHeaderChord loop = innerLoops.elementAt(li);
InductionVar ivar = loop.getPrimaryInductionVar();
if (trace) System.out.println(" lp " + loop.nestedLevel() + " " + loop);
if ((ivar == null) || !loop.isPerfectlyNested()) {
innerLoops.addVectors(loop.getInnerLoops());
continue;
}
if (loop.nestedLevel() < 2) // no need to check permutation for a simple nest
continue;
tryPermute(loop);
}
}
private void tryPermute(LoopHeaderChord topLoop) {
Vector<LoopHeaderChord> loopNest = topLoop.getTightlyNestedLoops();
if (loopNest == null) return;
int loopDepth = loopNest.size();
LoopHeaderChord bottom = loopNest.get(loopDepth - 1);
if (!unsafe && !legalLoop(bottom)) return;
// Set the loop costs for the loops in a loop nest. The cost for a loop is
// the cost of executing the nest with that loop in the innermost nesting.
Table<Declaration, SubscriptExpr> arrayRefs = new Table<Declaration, SubscriptExpr>();
if (!topLoop.getSubscriptsRecursive(arrayRefs)) return;
graph = topLoop.getDDGraph(false);
if (graph == null) return;
if (trace) System.out.println(" " + graph);
int[] loopIndex = new int[loopDepth];
Cost[] loopCostList = new Cost[loopDepth];
Vector<RefGroup> refGroups = new Vector<RefGroup>(20);
for (int i = 0; i < loopDepth; i++) {
LoopHeaderChord loop = loopNest.elementAt(i);
if (trace) System.out.println(" " + i + " " + loop);
computeRefGroups(loop.getNestedLevel(), 2, 2, arrayRefs, refGroups);
Cost lc = computeRefCostSum(loop, refGroups);
if (trace) System.out.println(" " + i + " " + lc);
loopCostList[i] = lc;
loopIndex[i] = i; // the outtermost loop is at position 0
Cost tp = tripProduct(loopNest, loop);
if (trace) System.out.println(" " + i + " " + tp);
lc.multiply(tp);
if (trace) System.out.println(" " + i + " " + lc);
}
boolean permuted = sortByCost(loopCostList, loopIndex);
if (!permuted) return;
if (trace) {
System.out.print(" permute " + loopDepth);
System.out.print(":");
for (int i = 0; i < loopIndex.length; i++) System.out.print(" " + loopIndex[i]);
System.out.println("");
}
int[][] ddVec = getDDVec(arrayRefs, loopDepth);
if (trace) printDDInfo(ddVec, loopDepth);
if (!isLegal(loopIndex, ddVec)) return;
if (trace) System.out.println(" permute " + loopDepth);
int[] rank = new int[loopDepth];
// We will do sorting on the rank vector, which corresponds to the interchange we need.
for (int i = 0; i < loopDepth; i++) {
int loopNum = loopIndex[i];
rank[loopNum] = i;
}
if (trace) printOrder(rank);
boolean changed = true;
while (changed) {
changed = false;
for (int i = 0; i < loopDepth - 1; i++) {
int j = i + 1;
int outerRank = rank[i];
int innerRank = rank[j];
if (innerRank >= outerRank) continue;
LoopHeaderChord innerLoop = loopNest.elementAt(j);
LoopHeaderChord outerLoop = loopNest.elementAt(i);
if (!outerLoop.isDDComplete() || outerLoop.inhibitLoopPermute()) continue;
if (!innerLoop.isDDComplete() || innerLoop.inhibitLoopPermute()) continue;
changed = true;
rank[i] = innerRank;
rank[j] = outerRank;
loopNest.setElementAt(innerLoop, i);
loopNest.setElementAt(outerLoop, j);
performLoopInterchange(innerLoop, outerLoop);
}
}
}
/**
* Compute the reference groups for this loop. Two array references are in the same group with
* respect to this loop if - there is a loop-independent dependence between them, or - the
* dependence distance(dependence vector entry dl) for this loop is less than some constant
* *dist*, and all other dependence vector entries are 0. - the two array refer to the same array
* and differ by at most *dist2* in the first subscript dimension, where d is less than or equal
* to the cache line size in terms of array elements. All other subscripts must be identical.
* Notes: Here we assume dist1 = dist2 = 2
*/
private void computeRefGroups(
int level,
int dist1,
int dist2,
Table<Declaration, SubscriptExpr> arrayRefs,
Vector<RefGroup> refGroups) {
if (arrayRefs == null) return;
Enumeration<Declaration> ek = arrayRefs.keys();
while (ek.hasMoreElements()) {
VariableDecl vd = (VariableDecl) ek.nextElement();
String s = vd.getName(); // array name
Object[] v = arrayRefs.getRowArray(vd); // vector of SubscriptExpr's
int vi = v.length;
for (int j = vi - 1; j >= 0; j--) {
SubscriptExpr sr = (SubscriptExpr) v[j];
Vector<LoopHeaderChord> allRelatedLoops =
sr.allRelatedLoops(); // ** Incorrect when something like a[(j+i][j]
int arls = allRelatedLoops.size();
int firstsub = arls - 1; // ** Making an invalid assumption here
// Process the list of references r' with which r has a data
// dependence, and r is the source(data flows from r to r').
RefGroup rg = new RefGroup(s, sr);
Object[] edges = graph.getEdges(sr);
int len = edges.length;
for (int i = 0; i < len; i++) {
DDEdge edge = (DDEdge) edges[i];
if (edge.isSpatial()) continue;
// Condition(1)-(a) in McKinley's paper
if (edge.isLoopIndependentDependency()) { // add rP to the RefGroup of r:
rg.add(edge);
continue;
}
// Condition(1)-(b) in McKinley's paper
computeEdgeRefs(edge, rg, level, dist1);
if (arls <= 0) continue;
// Condition(2) in McKinley's paper
// rlevel is the level of the loop related to the first subscript.
int rlevel = allRelatedLoops.elementAt(firstsub).getNestedLevel();
computeEdgeRefs(edge, rg, rlevel, dist2);
}
boolean isInExistingRefGroups = false;
int rgl = refGroups.size();
for (int i = 0; i < rgl; i++) {
RefGroup rg2 = refGroups.elementAt(i);
if (!rg2.getName().equals(s)) continue;
isInExistingRefGroups = rg2.contains(rg);
if (isInExistingRefGroups) {
rg2.add(rg);
break;
}
}
if (!isInExistingRefGroups) refGroups.addElement(rg);
}
}
}
private void printRefGroups(Vector<RefGroup> refGroups) {
for (int i = 0; i < refGroups.size(); i++) {
RefGroup rg = refGroups.elementAt(i);
System.out.println(rg);
}
}
public SubscriptExpr getRepresentative() {
if (refs.size() > 0) return (SubscriptExpr) refs.elementAt(0);
return null;
}