1 package Analysis.OwnershipAnalysis;
3 import Analysis.CallGraph.*;
6 import IR.Tree.Modifiers;
11 public class OwnershipAnalysis {
14 ///////////////////////////////////////////
16 // Public interface to discover possible
17 // aliases in the program under analysis
19 ///////////////////////////////////////////
21 public HashSet<AllocationSite>
22 getFlaggedAllocationSitesReachableFromTask(TaskDescriptor td) {
23 return getFlaggedAllocationSitesReachableFromTaskPRIVATE(td);
26 public AllocationSite getAllocationSiteFromFlatNew(FlatNew fn) {
27 return getAllocationSiteFromFlatNewPRIVATE(fn);
30 public boolean createsPotentialAliases(Descriptor taskOrMethod,
34 OwnershipGraph og = mapDescriptorToCompleteOwnershipGraph.get(taskOrMethod);
36 return og.hasPotentialAlias(paramIndex1, paramIndex2);
39 public boolean createsPotentialAliases(Descriptor taskOrMethod,
41 AllocationSite alloc) {
43 OwnershipGraph og = mapDescriptorToCompleteOwnershipGraph.get(taskOrMethod);
45 return og.hasPotentialAlias(paramIndex, alloc);
48 public boolean createsPotentialAliases(Descriptor taskOrMethod,
52 OwnershipGraph og = mapDescriptorToCompleteOwnershipGraph.get(taskOrMethod);
54 return og.hasPotentialAlias(paramIndex, alloc);
57 public boolean createsPotentialAliases(Descriptor taskOrMethod,
58 AllocationSite alloc1,
59 AllocationSite alloc2) {
61 OwnershipGraph og = mapDescriptorToCompleteOwnershipGraph.get(taskOrMethod);
63 return og.hasPotentialAlias(alloc1, alloc2);
66 // use the methods given above to check every possible alias
67 // between task parameters and flagged allocation sites reachable
69 public void writeAllAliases(String outputFile) throws java.io.IOException {
71 BufferedWriter bw = new BufferedWriter(new FileWriter(outputFile) );
73 bw.write("Conducting ownership analysis with allocation depth = "+allocationDepth);
75 // look through every task for potential aliases
76 Iterator taskItr = state.getTaskSymbolTable().getDescriptorsIterator();
77 while( taskItr.hasNext() ) {
78 TaskDescriptor td = (TaskDescriptor) taskItr.next();
80 bw.write("\n---------"+td+"--------\n");
82 HashSet<AllocationSite> allocSites = getFlaggedAllocationSitesReachableFromTask(td);
84 // for each task parameter, check for aliases with
85 // other task parameters and every allocation site
86 // reachable from this task
87 boolean foundSomeAlias = false;
89 FlatMethod fm = state.getMethodFlat(td);
90 for( int i = 0; i < fm.numParameters(); ++i ) {
92 // for the ith parameter check for aliases to all
93 // higher numbered parameters
94 for( int j = i + 1; j < fm.numParameters(); ++j ) {
95 if( createsPotentialAliases(td, i, j) ) {
96 foundSomeAlias = true;
97 bw.write("Potential alias between parameters "+i+" and "+j+".\n");
101 // for the ith parameter, check for aliases against
102 // the set of allocation sites reachable from this
104 Iterator allocItr = allocSites.iterator();
105 while( allocItr.hasNext() ) {
106 AllocationSite as = (AllocationSite) allocItr.next();
107 if( createsPotentialAliases(td, i, as) ) {
108 foundSomeAlias = true;
109 bw.write("Potential alias between parameter "+i+" and "+as+".\n");
114 // for each allocation site check for aliases with
115 // other allocation sites in the context of execution
117 HashSet<AllocationSite> outerChecked = new HashSet<AllocationSite>();
118 Iterator allocItr1 = allocSites.iterator();
119 while( allocItr1.hasNext() ) {
120 AllocationSite as1 = (AllocationSite) allocItr1.next();
122 Iterator allocItr2 = allocSites.iterator();
123 while( allocItr2.hasNext() ) {
124 AllocationSite as2 = (AllocationSite) allocItr2.next();
126 if( !outerChecked.contains(as2) &&
127 createsPotentialAliases(td, as1, as2) ) {
128 foundSomeAlias = true;
129 bw.write("Potential alias between "+as1+" and "+as2+".\n");
133 outerChecked.add(as1);
136 if( !foundSomeAlias ) {
137 bw.write("Task "+td+" contains no aliases between flagged objects.\n");
144 ///////////////////////////////////////////
146 // end public interface
148 ///////////////////////////////////////////
157 // data from the compiler
159 private TypeUtil typeUtil;
160 private CallGraph callGraph;
161 private int allocationDepth;
163 // used to identify HeapRegionNode objects
164 // A unique ID equates an object in one
165 // ownership graph with an object in another
166 // graph that logically represents the same
168 // start at 10 and incerement to leave some
169 // reserved IDs for special purposes
170 static private int uniqueIDcount = 10;
173 // Use these data structures to track progress of
174 // processing all methods in the program, and by methods
175 // TaskDescriptor and MethodDescriptor are combined
176 // together, with a common parent class Descriptor
177 private Hashtable<FlatMethod, OwnershipGraph> mapFlatMethodToInitialParamAllocGraph;
178 private Hashtable<Descriptor, OwnershipGraph> mapDescriptorToCompleteOwnershipGraph;
179 private Hashtable<FlatNew, AllocationSite> mapFlatNewToAllocationSite;
180 private Hashtable<Descriptor, HashSet<AllocationSite> > mapDescriptorToAllocationSiteSet;
181 private Hashtable<Descriptor, Integer> mapDescriptorToNumUpdates;
183 // Use these data structures to track progress of one pass of
184 // processing the FlatNodes of a particular method
185 private HashSet <FlatNode> flatNodesToVisit;
186 private Hashtable<FlatNode, OwnershipGraph> mapFlatNodeToOwnershipGraph;
187 private HashSet <FlatReturnNode> returnNodesToCombineForCompleteOwnershipGraph;
189 // descriptorsToAnalyze identifies the set of tasks and methods
190 // that are reachable from the program tasks, this set is initialized
191 // and then remains static
192 private HashSet<Descriptor> descriptorsToAnalyze;
194 // descriptorsToVisit is initialized to descriptorsToAnalyze and is
195 // reduced by visiting a descriptor during analysis. When dependents
196 // must be scheduled, only those contained in descriptorsToAnalyze
197 // should be re-added to this set
198 private HashSet<Descriptor> descriptorsToVisit;
200 // a special field descriptor for all array elements
201 private static FieldDescriptor fdElement = new FieldDescriptor(new Modifiers(Modifiers.PUBLIC),
202 new TypeDescriptor("Array[]"),
206 // for controlling DOT file output
207 private boolean writeDOTs;
208 private boolean writeAllDOTs;
212 // this analysis generates an ownership graph for every task
214 public OwnershipAnalysis(State state,
219 boolean writeAllDOTs,
220 String aliasFile) throws java.io.IOException {
224 this.callGraph = callGraph;
225 this.allocationDepth = allocationDepth;
226 this.writeDOTs = writeDOTs;
227 this.writeAllDOTs = writeAllDOTs;
229 descriptorsToAnalyze = new HashSet<Descriptor>();
231 mapFlatMethodToInitialParamAllocGraph =
232 new Hashtable<FlatMethod, OwnershipGraph>();
234 mapDescriptorToCompleteOwnershipGraph =
235 new Hashtable<Descriptor, OwnershipGraph>();
237 mapFlatNewToAllocationSite =
238 new Hashtable<FlatNew, AllocationSite>();
240 mapDescriptorToAllocationSiteSet =
241 new Hashtable<Descriptor, HashSet<AllocationSite> >();
244 mapDescriptorToNumUpdates = new Hashtable<Descriptor, Integer>();
247 // initialize methods to visit as the set of all tasks in the
248 // program and then any method that could be called starting
250 Iterator taskItr = state.getTaskSymbolTable().getDescriptorsIterator();
251 while( taskItr.hasNext() ) {
252 Descriptor d = (Descriptor) taskItr.next();
253 scheduleAllCallees(d);
256 // before beginning analysis, initialize every scheduled method
257 // with an ownership graph that has populated parameter index tables
258 // by analyzing the first node which is always a FlatMethod node
259 Iterator<Descriptor> dItr = descriptorsToAnalyze.iterator();
260 while( dItr.hasNext() ) {
261 Descriptor d = dItr.next();
262 OwnershipGraph og = new OwnershipGraph(allocationDepth, typeUtil);
265 if( d instanceof MethodDescriptor ) {
266 fm = state.getMethodFlat( (MethodDescriptor) d);
268 assert d instanceof TaskDescriptor;
269 fm = state.getMethodFlat( (TaskDescriptor) d);
272 System.out.println("Previsiting " + d);
274 og = analyzeFlatNode(d, fm, null, og);
275 setGraphForDescriptor(d, og);
278 System.out.println("");
280 // as mentioned above, analyze methods one-by-one, possibly revisiting
281 // a method if the methods that it calls are updated
284 System.out.println("");
286 if( aliasFile != null ) {
287 writeAllAliases(aliasFile);
291 // called from the constructor to help initialize the set
292 // of methods that needs to be analyzed by ownership analysis
293 private void scheduleAllCallees(Descriptor d) {
294 if( descriptorsToAnalyze.contains(d) ) {
297 descriptorsToAnalyze.add(d);
299 // start with all method calls to further schedule
300 Set moreMethodsToCheck = moreMethodsToCheck = callGraph.getMethodCalls(d);
302 if( d instanceof MethodDescriptor ) {
303 // see if this method has virtual dispatch
304 Set virtualMethods = callGraph.getMethods( (MethodDescriptor)d);
305 moreMethodsToCheck.addAll(virtualMethods);
308 // keep following any further methods identified in
310 Iterator methItr = moreMethodsToCheck.iterator();
311 while( methItr.hasNext() ) {
312 Descriptor m = (Descriptor) methItr.next();
313 scheduleAllCallees(m);
318 // manage the set of tasks and methods to be analyzed
319 // and be sure to reschedule tasks/methods when the methods
320 // they call are updated
321 private void analyzeMethods() throws java.io.IOException {
323 descriptorsToVisit = (HashSet<Descriptor>)descriptorsToAnalyze.clone();
325 while( !descriptorsToVisit.isEmpty() ) {
326 Descriptor d = (Descriptor) descriptorsToVisit.iterator().next();
327 descriptorsToVisit.remove(d);
329 // because the task or method descriptor just extracted
330 // was in the "to visit" set it either hasn't been analyzed
331 // yet, or some method that it depends on has been
332 // updated. Recompute a complete ownership graph for
333 // this task/method and compare it to any previous result.
334 // If there is a change detected, add any methods/tasks
335 // that depend on this one to the "to visit" set.
337 System.out.println("Analyzing " + d);
340 if( d instanceof MethodDescriptor ) {
341 fm = state.getMethodFlat( (MethodDescriptor) d);
343 assert d instanceof TaskDescriptor;
344 fm = state.getMethodFlat( (TaskDescriptor) d);
347 OwnershipGraph og = analyzeFlatMethod(d, fm);
348 OwnershipGraph ogPrev = mapDescriptorToCompleteOwnershipGraph.get(d);
349 if( !og.equals(ogPrev) ) {
351 setGraphForDescriptor(d, og);
353 // only methods have dependents, tasks cannot
354 // be invoked by any user program calls
355 if( d instanceof MethodDescriptor ) {
356 MethodDescriptor md = (MethodDescriptor) d;
357 Set dependents = callGraph.getCallerSet(md);
358 if( dependents != null ) {
359 Iterator depItr = dependents.iterator();
360 while( depItr.hasNext() ) {
361 Descriptor dependent = (Descriptor) depItr.next();
362 if( descriptorsToAnalyze.contains(dependent) ) {
363 descriptorsToVisit.add(dependent);
374 // keep passing the Descriptor of the method along for debugging
375 // and dot file writing
376 private OwnershipGraph
377 analyzeFlatMethod(Descriptor mDesc,
378 FlatMethod flatm) throws java.io.IOException {
380 // initialize flat nodes to visit as the flat method
381 // because all other nodes in this flat method are
382 // decendents of the flat method itself
384 flatNodesToVisit = new HashSet<FlatNode>();
385 flatNodesToVisit.add(flatm);
387 // initilize the mapping of flat nodes in this flat method to
388 // ownership graph results to an empty mapping
389 mapFlatNodeToOwnershipGraph = new Hashtable<FlatNode, OwnershipGraph>();
391 // initialize the set of return nodes that will be combined as
392 // the final ownership graph result to return as an empty set
393 returnNodesToCombineForCompleteOwnershipGraph = new HashSet<FlatReturnNode>();
396 while( !flatNodesToVisit.isEmpty() ) {
397 FlatNode fn = (FlatNode) flatNodesToVisit.iterator().next();
398 flatNodesToVisit.remove(fn);
400 // perform this node's contributions to the ownership
401 // graph on a new copy, then compare it to the old graph
402 // at this node to see if anything was updated.
403 OwnershipGraph og = new OwnershipGraph(allocationDepth, typeUtil);
405 // start by merging all node's parents' graphs
406 for( int i = 0; i < fn.numPrev(); ++i ) {
407 FlatNode pn = fn.getPrev(i);
408 OwnershipGraph ogParent = getGraphFromFlatNode(pn);
412 // apply the analysis of the flat node to the
413 // ownership graph made from the merge of the
415 og = analyzeFlatNode(mDesc,
417 returnNodesToCombineForCompleteOwnershipGraph,
420 // if the results of the new graph are different from
421 // the current graph at this node, replace the graph
422 // with the update and enqueue the children for
424 OwnershipGraph ogPrev = getGraphFromFlatNode(fn);
426 if( !og.equals(ogPrev) ) {
427 setGraphForFlatNode(fn, og);
429 for( int i = 0; i < fn.numNext(); i++ ) {
430 FlatNode nn = fn.getNext(i);
431 flatNodesToVisit.add(nn);
436 // end by merging all return nodes into a complete
437 // ownership graph that represents all possible heap
438 // states after the flat method returns
439 OwnershipGraph completeGraph = new OwnershipGraph(allocationDepth, typeUtil);
440 Iterator retItr = returnNodesToCombineForCompleteOwnershipGraph.iterator();
441 while( retItr.hasNext() ) {
442 FlatReturnNode frn = (FlatReturnNode) retItr.next();
443 OwnershipGraph ogr = getGraphFromFlatNode(frn);
444 completeGraph.merge(ogr);
446 return completeGraph;
450 private OwnershipGraph
451 analyzeFlatNode(Descriptor methodDesc,
453 HashSet<FlatReturnNode> setRetNodes,
454 OwnershipGraph og) throws java.io.IOException {
460 //System.out.println(" "+fn.kind());
462 // use node type to decide what alterations to make
463 // to the ownership graph
464 switch( fn.kind() ) {
466 case FKind.FlatMethod:
467 FlatMethod fm = (FlatMethod) fn;
469 // there should only be one FlatMethod node as the
470 // parent of all other FlatNode objects, so take
471 // the opportunity to construct the initial graph by
472 // adding parameters labels to new heap regions
473 // AND this should be done once globally so that the
474 // parameter IDs are consistent between analysis
475 // iterations, so if this step has been done already
476 // just merge in the cached version
477 OwnershipGraph ogInitParamAlloc = mapFlatMethodToInitialParamAllocGraph.get(fm);
478 if( ogInitParamAlloc == null ) {
480 // analyze this node one time globally
481 for( int i = 0; i < fm.numParameters(); ++i ) {
482 TempDescriptor tdParam = fm.getParameter(i);
483 og.assignTempEqualToParamAlloc(tdParam,
484 methodDesc instanceof TaskDescriptor,
489 OwnershipGraph ogResult = new OwnershipGraph(allocationDepth, typeUtil);
491 mapFlatMethodToInitialParamAllocGraph.put(fm, ogResult);
494 // or just leverage the cached copy
495 og.merge(ogInitParamAlloc);
499 case FKind.FlatOpNode:
500 FlatOpNode fon = (FlatOpNode) fn;
501 if( fon.getOp().getOp() == Operation.ASSIGN ) {
504 og.assignTempXEqualToTempY(lhs, rhs);
508 case FKind.FlatFieldNode:
509 FlatFieldNode ffn = (FlatFieldNode) fn;
512 fld = ffn.getField();
513 if( !fld.getType().isPrimitive() ) {
514 og.assignTempXEqualToTempYFieldF(lhs, rhs, fld);
518 case FKind.FlatSetFieldNode:
519 FlatSetFieldNode fsfn = (FlatSetFieldNode) fn;
521 fld = fsfn.getField();
523 og.assignTempXFieldFEqualToTempY(lhs, fld, rhs);
526 case FKind.FlatElementNode:
527 FlatElementNode fen = (FlatElementNode) fn;
530 if( !lhs.getType().isPrimitive() ) {
531 og.assignTempXEqualToTempYFieldF(lhs, rhs, fdElement);
535 case FKind.FlatSetElementNode:
536 FlatSetElementNode fsen = (FlatSetElementNode) fn;
539 if( !rhs.getType().isPrimitive() ) {
540 og.assignTempXFieldFEqualToTempY(lhs, fdElement, rhs);
545 FlatNew fnn = (FlatNew) fn;
547 AllocationSite as = getAllocationSiteFromFlatNewPRIVATE(fnn);
549 og.assignTempEqualToNewAlloc(lhs, as);
553 FlatCall fc = (FlatCall) fn;
554 MethodDescriptor md = fc.getMethod();
555 FlatMethod flatm = state.getMethodFlat(md);
556 OwnershipGraph ogMergeOfAllPossibleCalleeResults = new OwnershipGraph(allocationDepth, typeUtil);
558 if( md.isStatic() ) {
559 // a static method is simply always the same, makes life easy
560 OwnershipGraph onlyPossibleCallee = mapDescriptorToCompleteOwnershipGraph.get(md);
561 ogMergeOfAllPossibleCalleeResults = og;
562 ogMergeOfAllPossibleCalleeResults.resolveMethodCall(fc, md.isStatic(), flatm, onlyPossibleCallee);
564 // if the method descriptor is virtual, then there could be a
565 // set of possible methods that will actually be invoked, so
566 // find all of them and merge all of their results together
567 TypeDescriptor typeDesc = fc.getThis().getType();
568 Set possibleCallees = callGraph.getMethods(md, typeDesc);
570 Iterator i = possibleCallees.iterator();
571 while( i.hasNext() ) {
572 MethodDescriptor possibleMd = (MethodDescriptor) i.next();
574 // don't alter the working graph (og) until we compute a result for every
575 // possible callee, merge them all together, then set og to that
576 OwnershipGraph ogCopy = new OwnershipGraph(allocationDepth, typeUtil);
579 OwnershipGraph ogPotentialCallee = mapDescriptorToCompleteOwnershipGraph.get(possibleMd);
580 ogCopy.resolveMethodCall(fc, md.isStatic(), flatm, ogPotentialCallee);
581 ogMergeOfAllPossibleCalleeResults.merge(ogCopy);
585 og = ogMergeOfAllPossibleCalleeResults;
588 case FKind.FlatReturnNode:
589 FlatReturnNode frn = (FlatReturnNode) fn;
590 rhs = frn.getReturnTemp();
593 og.assignReturnEqualToTemp(rhs);
596 setRetNodes.add(frn);
604 og.writeGraph( String.format("test%04d",x-10000)+fn, true, true, true, false );
620 // this method should generate integers strictly greater than zero!
621 // special "shadow" regions are made from a heap region by negating
623 static public Integer generateUniqueHeapRegionNodeID() {
625 return new Integer(uniqueIDcount);
629 private void setGraphForDescriptor(Descriptor d, OwnershipGraph og)
632 mapDescriptorToCompleteOwnershipGraph.put(d, og);
634 // arguments to writeGraph are:
635 // boolean writeLabels,
636 // boolean labelSelect,
637 // boolean pruneGarbage,
638 // boolean writeReferencers
642 if( !writeAllDOTs ) {
643 og.writeGraph(d, true, true, true, false);
646 if( !mapDescriptorToNumUpdates.containsKey(d) ) {
647 mapDescriptorToNumUpdates.put(d, new Integer(0) );
649 Integer n = mapDescriptorToNumUpdates.get(d);
650 og.writeGraph(d, n, true, true, true, false);
651 mapDescriptorToNumUpdates.put(d, n + 1);
657 private OwnershipGraph getGraphFromFlatNode(FlatNode fn) {
658 if( !mapFlatNodeToOwnershipGraph.containsKey(fn) ) {
659 mapFlatNodeToOwnershipGraph.put(fn, new OwnershipGraph(allocationDepth, typeUtil) );
662 return mapFlatNodeToOwnershipGraph.get(fn);
665 private void setGraphForFlatNode(FlatNode fn, OwnershipGraph og) {
666 mapFlatNodeToOwnershipGraph.put(fn, og);
670 // return just the allocation site associated with one FlatNew node
671 private AllocationSite getAllocationSiteFromFlatNewPRIVATE(FlatNew fn) {
673 if( !mapFlatNewToAllocationSite.containsKey(fn) ) {
674 AllocationSite as = new AllocationSite(allocationDepth, fn.getType() );
676 // the newest nodes are single objects
677 for( int i = 0; i < allocationDepth; ++i ) {
678 Integer id = generateUniqueHeapRegionNodeID();
679 as.setIthOldest(i, id);
682 // the oldest node is a summary node
683 Integer idSummary = generateUniqueHeapRegionNodeID();
684 as.setSummary(idSummary);
686 mapFlatNewToAllocationSite.put(fn, as);
689 return mapFlatNewToAllocationSite.get(fn);
693 // return all allocation sites in the method (there is one allocation
694 // site per FlatNew node in a method)
695 private HashSet<AllocationSite> getAllocationSiteSet(Descriptor d) {
696 if( !mapDescriptorToAllocationSiteSet.containsKey(d) ) {
697 buildAllocationSiteSet(d);
700 return mapDescriptorToAllocationSiteSet.get(d);
704 private void buildAllocationSiteSet(Descriptor d) {
705 HashSet<AllocationSite> s = new HashSet<AllocationSite>();
708 if( d instanceof MethodDescriptor ) {
709 fm = state.getMethodFlat( (MethodDescriptor) d);
711 assert d instanceof TaskDescriptor;
712 fm = state.getMethodFlat( (TaskDescriptor) d);
715 // visit every node in this FlatMethod's IR graph
716 // and make a set of the allocation sites from the
717 // FlatNew node's visited
718 HashSet<FlatNode> visited = new HashSet<FlatNode>();
719 HashSet<FlatNode> toVisit = new HashSet<FlatNode>();
722 while( !toVisit.isEmpty() ) {
723 FlatNode n = toVisit.iterator().next();
725 if( n instanceof FlatNew ) {
726 s.add(getAllocationSiteFromFlatNewPRIVATE( (FlatNew) n) );
732 for( int i = 0; i < n.numNext(); ++i ) {
733 FlatNode child = n.getNext(i);
734 if( !visited.contains(child) ) {
740 mapDescriptorToAllocationSiteSet.put(d, s);
744 private HashSet<AllocationSite>
745 getFlaggedAllocationSitesReachableFromTaskPRIVATE(TaskDescriptor td) {
747 HashSet<AllocationSite> asSetTotal = new HashSet<AllocationSite>();
748 HashSet<Descriptor> toVisit = new HashSet<Descriptor>();
749 HashSet<Descriptor> visited = new HashSet<Descriptor>();
753 // traverse this task and all methods reachable from this task
754 while( !toVisit.isEmpty() ) {
755 Descriptor d = toVisit.iterator().next();
759 HashSet<AllocationSite> asSet = getAllocationSiteSet(d);
760 Iterator asItr = asSet.iterator();
761 while( asItr.hasNext() ) {
762 AllocationSite as = (AllocationSite) asItr.next();
763 TypeDescriptor typed = as.getType();
764 if( typed != null ) {
765 ClassDescriptor cd = typed.getClassDesc();
766 if( cd != null && cd.hasFlags() ) {
772 // enqueue callees of this method to be searched for
773 // allocation sites also
774 Set callees = callGraph.getCalleeSet(d);
775 if( callees != null ) {
776 Iterator methItr = callees.iterator();
777 while( methItr.hasNext() ) {
778 MethodDescriptor md = (MethodDescriptor) methItr.next();
780 if( !visited.contains(md) ) {