1 //===- DataStructure.cpp - Implement the core data structure analysis -----===//
3 // This file implements the core data structure functionality.
5 //===----------------------------------------------------------------------===//
7 #include "llvm/Analysis/DSGraph.h"
8 #include "llvm/Function.h"
9 #include "llvm/iOther.h"
10 #include "llvm/DerivedTypes.h"
11 #include "llvm/Target/TargetData.h"
12 #include "Support/STLExtras.h"
13 #include "Support/Statistic.h"
14 #include "Support/Timer.h"
18 Statistic<> NumFolds ("dsnode", "Number of nodes completely folded");
19 Statistic<> NumCallNodesMerged("dsnode", "Number of call nodes merged");
22 namespace DS { // TODO: FIXME
27 DSNode *DSNodeHandle::HandleForwarding() const {
28 assert(!N->ForwardNH.isNull() && "Can only be invoked if forwarding!");
30 // Handle node forwarding here!
31 DSNode *Next = N->ForwardNH.getNode(); // Cause recursive shrinkage
32 Offset += N->ForwardNH.getOffset();
34 if (--N->NumReferrers == 0) {
35 // Removing the last referrer to the node, sever the forwarding link
41 if (N->Size <= Offset) {
42 assert(N->Size <= 1 && "Forwarded to shrunk but not collapsed node?");
48 //===----------------------------------------------------------------------===//
49 // DSNode Implementation
50 //===----------------------------------------------------------------------===//
52 DSNode::DSNode(unsigned NT, const Type *T, DSGraph *G)
53 : NumReferrers(0), Size(0), ParentGraph(G), Ty(Type::VoidTy), NodeType(NT) {
54 // Add the type entry if it is specified...
55 if (T) mergeTypeInfo(T, 0);
56 G->getNodes().push_back(this);
59 // DSNode copy constructor... do not copy over the referrers list!
60 DSNode::DSNode(const DSNode &N, DSGraph *G)
61 : NumReferrers(0), Size(N.Size), ParentGraph(G), Ty(N.Ty),
62 Links(N.Links), Globals(N.Globals), NodeType(N.NodeType) {
63 G->getNodes().push_back(this);
66 void DSNode::assertOK() const {
67 assert((Ty != Type::VoidTy ||
68 Ty == Type::VoidTy && (Size == 0 ||
69 (NodeType & DSNode::Array))) &&
73 /// forwardNode - Mark this node as being obsolete, and all references to it
74 /// should be forwarded to the specified node and offset.
76 void DSNode::forwardNode(DSNode *To, unsigned Offset) {
77 assert(this != To && "Cannot forward a node to itself!");
78 assert(ForwardNH.isNull() && "Already forwarding from this node!");
79 if (To->Size <= 1) Offset = 0;
80 assert((Offset < To->Size || (Offset == To->Size && Offset == 0)) &&
81 "Forwarded offset is wrong!");
82 ForwardNH.setNode(To);
83 ForwardNH.setOffset(Offset);
89 // addGlobal - Add an entry for a global value to the Globals list. This also
90 // marks the node with the 'G' flag if it does not already have it.
92 void DSNode::addGlobal(GlobalValue *GV) {
93 // Keep the list sorted.
94 std::vector<GlobalValue*>::iterator I =
95 std::lower_bound(Globals.begin(), Globals.end(), GV);
97 if (I == Globals.end() || *I != GV) {
98 //assert(GV->getType()->getElementType() == Ty);
99 Globals.insert(I, GV);
100 NodeType |= GlobalNode;
104 /// foldNodeCompletely - If we determine that this node has some funny
105 /// behavior happening to it that we cannot represent, we fold it down to a
106 /// single, completely pessimistic, node. This node is represented as a
107 /// single byte with a single TypeEntry of "void".
109 void DSNode::foldNodeCompletely() {
110 assert(!hasNoReferrers() &&
111 "Why would we collapse a node with no referrers?");
112 if (isNodeCompletelyFolded()) return; // If this node is already folded...
116 // Create the node we are going to forward to...
117 DSNode *DestNode = new DSNode(NodeType|DSNode::Array, 0, ParentGraph);
118 DestNode->Ty = Type::VoidTy;
120 DestNode->Globals.swap(Globals);
122 // Start forwarding to the destination node...
123 forwardNode(DestNode, 0);
126 DestNode->Links.push_back(Links[0]);
127 DSNodeHandle NH(DestNode);
129 // If we have links, merge all of our outgoing links together...
130 for (unsigned i = Links.size()-1; i != 0; --i)
131 NH.getNode()->Links[0].mergeWith(Links[i]);
134 DestNode->Links.resize(1);
138 /// isNodeCompletelyFolded - Return true if this node has been completely
139 /// folded down to something that can never be expanded, effectively losing
140 /// all of the field sensitivity that may be present in the node.
142 bool DSNode::isNodeCompletelyFolded() const {
143 return getSize() == 1 && Ty == Type::VoidTy && isArray();
147 /// mergeTypeInfo - This method merges the specified type into the current node
148 /// at the specified offset. This may update the current node's type record if
149 /// this gives more information to the node, it may do nothing to the node if
150 /// this information is already known, or it may merge the node completely (and
151 /// return true) if the information is incompatible with what is already known.
153 /// This method returns true if the node is completely folded, otherwise false.
155 bool DSNode::mergeTypeInfo(const Type *NewTy, unsigned Offset) {
156 // Check to make sure the Size member is up-to-date. Size can be one of the
158 // Size = 0, Ty = Void: Nothing is known about this node.
159 // Size = 0, Ty = FnTy: FunctionPtr doesn't have a size, so we use zero
160 // Size = 1, Ty = Void, Array = 1: The node is collapsed
161 // Otherwise, sizeof(Ty) = Size
163 assert(((Size == 0 && Ty == Type::VoidTy && !isArray()) ||
164 (Size == 0 && !Ty->isSized() && !isArray()) ||
165 (Size == 1 && Ty == Type::VoidTy && isArray()) ||
166 (Size == 0 && !Ty->isSized() && !isArray()) ||
167 (TD.getTypeSize(Ty) == Size)) &&
168 "Size member of DSNode doesn't match the type structure!");
169 assert(NewTy != Type::VoidTy && "Cannot merge void type into DSNode!");
171 if (Offset == 0 && NewTy == Ty)
172 return false; // This should be a common case, handle it efficiently
174 // Return true immediately if the node is completely folded.
175 if (isNodeCompletelyFolded()) return true;
177 // If this is an array type, eliminate the outside arrays because they won't
178 // be used anyway. This greatly reduces the size of large static arrays used
179 // as global variables, for example.
181 bool WillBeArray = false;
182 while (const ArrayType *AT = dyn_cast<ArrayType>(NewTy)) {
183 // FIXME: we might want to keep small arrays, but must be careful about
184 // things like: [2 x [10000 x int*]]
185 NewTy = AT->getElementType();
189 // Figure out how big the new type we're merging in is...
190 unsigned NewTySize = NewTy->isSized() ? TD.getTypeSize(NewTy) : 0;
192 // Otherwise check to see if we can fold this type into the current node. If
193 // we can't, we fold the node completely, if we can, we potentially update our
196 if (Ty == Type::VoidTy) {
197 // If this is the first type that this node has seen, just accept it without
199 assert(Offset == 0 && "Cannot have an offset into a void node!");
200 assert(!isArray() && "This shouldn't happen!");
203 if (WillBeArray) NodeType |= Array;
206 // Calculate the number of outgoing links from this node.
207 Links.resize((Size+DS::PointerSize-1) >> DS::PointerShift);
211 // Handle node expansion case here...
212 if (Offset+NewTySize > Size) {
213 // It is illegal to grow this node if we have treated it as an array of
216 foldNodeCompletely();
220 if (Offset) { // We could handle this case, but we don't for now...
221 DEBUG(std::cerr << "UNIMP: Trying to merge a growth type into "
222 << "offset != 0: Collapsing!\n");
223 foldNodeCompletely();
227 // Okay, the situation is nice and simple, we are trying to merge a type in
228 // at offset 0 that is bigger than our current type. Implement this by
229 // switching to the new type and then merge in the smaller one, which should
230 // hit the other code path here. If the other code path decides it's not
231 // ok, it will collapse the node as appropriate.
233 const Type *OldTy = Ty;
236 if (WillBeArray) NodeType |= Array;
239 // Must grow links to be the appropriate size...
240 Links.resize((Size+DS::PointerSize-1) >> DS::PointerShift);
242 // Merge in the old type now... which is guaranteed to be smaller than the
244 return mergeTypeInfo(OldTy, 0);
247 assert(Offset <= Size &&
248 "Cannot merge something into a part of our type that doesn't exist!");
250 // Find the section of Ty that NewTy overlaps with... first we find the
251 // type that starts at offset Offset.
254 const Type *SubType = Ty;
256 assert(Offset-O < TD.getTypeSize(SubType) && "Offset out of range!");
258 switch (SubType->getPrimitiveID()) {
259 case Type::StructTyID: {
260 const StructType *STy = cast<StructType>(SubType);
261 const StructLayout &SL = *TD.getStructLayout(STy);
263 unsigned i = 0, e = SL.MemberOffsets.size();
264 for (; i+1 < e && SL.MemberOffsets[i+1] <= Offset-O; ++i)
267 // The offset we are looking for must be in the i'th element...
268 SubType = STy->getElementTypes()[i];
269 O += SL.MemberOffsets[i];
272 case Type::ArrayTyID: {
273 SubType = cast<ArrayType>(SubType)->getElementType();
274 unsigned ElSize = TD.getTypeSize(SubType);
275 unsigned Remainder = (Offset-O) % ElSize;
276 O = Offset-Remainder;
280 foldNodeCompletely();
285 assert(O == Offset && "Could not achieve the correct offset!");
287 // If we found our type exactly, early exit
288 if (SubType == NewTy) return false;
290 // Okay, so we found the leader type at the offset requested. Search the list
291 // of types that starts at this offset. If SubType is currently an array or
292 // structure, the type desired may actually be the first element of the
295 unsigned SubTypeSize = SubType->isSized() ? TD.getTypeSize(SubType) : 0;
296 unsigned PadSize = SubTypeSize; // Size, including pad memory which is ignored
297 while (SubType != NewTy) {
298 const Type *NextSubType = 0;
299 unsigned NextSubTypeSize = 0;
300 unsigned NextPadSize = 0;
301 switch (SubType->getPrimitiveID()) {
302 case Type::StructTyID: {
303 const StructType *STy = cast<StructType>(SubType);
304 const StructLayout &SL = *TD.getStructLayout(STy);
305 if (SL.MemberOffsets.size() > 1)
306 NextPadSize = SL.MemberOffsets[1];
308 NextPadSize = SubTypeSize;
309 NextSubType = STy->getElementTypes()[0];
310 NextSubTypeSize = TD.getTypeSize(NextSubType);
313 case Type::ArrayTyID:
314 NextSubType = cast<ArrayType>(SubType)->getElementType();
315 NextSubTypeSize = TD.getTypeSize(NextSubType);
316 NextPadSize = NextSubTypeSize;
322 if (NextSubType == 0)
323 break; // In the default case, break out of the loop
325 if (NextPadSize < NewTySize)
326 break; // Don't allow shrinking to a smaller type than NewTySize
327 SubType = NextSubType;
328 SubTypeSize = NextSubTypeSize;
329 PadSize = NextPadSize;
332 // If we found the type exactly, return it...
333 if (SubType == NewTy)
336 // Check to see if we have a compatible, but different type...
337 if (NewTySize == SubTypeSize) {
338 // Check to see if this type is obviously convertable... int -> uint f.e.
339 if (NewTy->isLosslesslyConvertableTo(SubType))
342 // Check to see if we have a pointer & integer mismatch going on here,
343 // loading a pointer as a long, for example.
345 if (SubType->isInteger() && isa<PointerType>(NewTy) ||
346 NewTy->isInteger() && isa<PointerType>(SubType))
348 } else if (NewTySize > SubTypeSize && NewTySize <= PadSize) {
349 // We are accessing the field, plus some structure padding. Ignore the
350 // structure padding.
355 DEBUG(std::cerr << "MergeTypeInfo Folding OrigTy: " << Ty
356 << "\n due to:" << NewTy << " @ " << Offset << "!\n"
357 << "SubType: " << SubType << "\n\n");
359 foldNodeCompletely();
365 // addEdgeTo - Add an edge from the current node to the specified node. This
366 // can cause merging of nodes in the graph.
368 void DSNode::addEdgeTo(unsigned Offset, const DSNodeHandle &NH) {
369 if (NH.getNode() == 0) return; // Nothing to do
371 DSNodeHandle &ExistingEdge = getLink(Offset);
372 if (ExistingEdge.getNode()) {
373 // Merge the two nodes...
374 ExistingEdge.mergeWith(NH);
375 } else { // No merging to perform...
376 setLink(Offset, NH); // Just force a link in there...
381 // MergeSortedVectors - Efficiently merge a vector into another vector where
382 // duplicates are not allowed and both are sorted. This assumes that 'T's are
383 // efficiently copyable and have sane comparison semantics.
385 static void MergeSortedVectors(std::vector<GlobalValue*> &Dest,
386 const std::vector<GlobalValue*> &Src) {
387 // By far, the most common cases will be the simple ones. In these cases,
388 // avoid having to allocate a temporary vector...
390 if (Src.empty()) { // Nothing to merge in...
392 } else if (Dest.empty()) { // Just copy the result in...
394 } else if (Src.size() == 1) { // Insert a single element...
395 const GlobalValue *V = Src[0];
396 std::vector<GlobalValue*>::iterator I =
397 std::lower_bound(Dest.begin(), Dest.end(), V);
398 if (I == Dest.end() || *I != Src[0]) // If not already contained...
399 Dest.insert(I, Src[0]);
400 } else if (Dest.size() == 1) {
401 GlobalValue *Tmp = Dest[0]; // Save value in temporary...
402 Dest = Src; // Copy over list...
403 std::vector<GlobalValue*>::iterator I =
404 std::lower_bound(Dest.begin(), Dest.end(), Tmp);
405 if (I == Dest.end() || *I != Tmp) // If not already contained...
409 // Make a copy to the side of Dest...
410 std::vector<GlobalValue*> Old(Dest);
412 // Make space for all of the type entries now...
413 Dest.resize(Dest.size()+Src.size());
415 // Merge the two sorted ranges together... into Dest.
416 std::merge(Old.begin(), Old.end(), Src.begin(), Src.end(), Dest.begin());
418 // Now erase any duplicate entries that may have accumulated into the
419 // vectors (because they were in both of the input sets)
420 Dest.erase(std::unique(Dest.begin(), Dest.end()), Dest.end());
425 // MergeNodes() - Helper function for DSNode::mergeWith().
426 // This function does the hard work of merging two nodes, CurNodeH
427 // and NH after filtering out trivial cases and making sure that
428 // CurNodeH.offset >= NH.offset.
431 // Since merging may cause either node to go away, we must always
432 // use the node-handles to refer to the nodes. These node handles are
433 // automatically updated during merging, so will always provide access
434 // to the correct node after a merge.
436 void DSNode::MergeNodes(DSNodeHandle& CurNodeH, DSNodeHandle& NH) {
437 assert(CurNodeH.getOffset() >= NH.getOffset() &&
438 "This should have been enforced in the caller.");
440 // Now we know that Offset >= NH.Offset, so convert it so our "Offset" (with
441 // respect to NH.Offset) is now zero. NOffset is the distance from the base
442 // of our object that N starts from.
444 unsigned NOffset = CurNodeH.getOffset()-NH.getOffset();
445 unsigned NSize = NH.getNode()->getSize();
447 // Merge the type entries of the two nodes together...
448 if (NH.getNode()->Ty != Type::VoidTy)
449 CurNodeH.getNode()->mergeTypeInfo(NH.getNode()->Ty, NOffset);
450 assert((CurNodeH.getNode()->NodeType & DSNode::DEAD) == 0);
452 // If we are merging a node with a completely folded node, then both nodes are
453 // now completely folded.
455 if (CurNodeH.getNode()->isNodeCompletelyFolded()) {
456 if (!NH.getNode()->isNodeCompletelyFolded()) {
457 NH.getNode()->foldNodeCompletely();
458 assert(NH.getNode() && NH.getOffset() == 0 &&
459 "folding did not make offset 0?");
460 NOffset = NH.getOffset();
461 NSize = NH.getNode()->getSize();
462 assert(NOffset == 0 && NSize == 1);
464 } else if (NH.getNode()->isNodeCompletelyFolded()) {
465 CurNodeH.getNode()->foldNodeCompletely();
466 assert(CurNodeH.getNode() && CurNodeH.getOffset() == 0 &&
467 "folding did not make offset 0?");
468 NOffset = NH.getOffset();
469 NSize = NH.getNode()->getSize();
470 assert(NOffset == 0 && NSize == 1);
473 DSNode *N = NH.getNode();
474 if (CurNodeH.getNode() == N || N == 0) return;
475 assert((CurNodeH.getNode()->NodeType & DSNode::DEAD) == 0);
477 // Start forwarding to the new node!
478 CurNodeH.getNode()->NodeType |= N->NodeType;
479 N->forwardNode(CurNodeH.getNode(), NOffset);
480 assert((CurNodeH.getNode()->NodeType & DSNode::DEAD) == 0);
482 // Make all of the outgoing links of N now be outgoing links of CurNodeH.
484 for (unsigned i = 0; i < N->getNumLinks(); ++i) {
485 DSNodeHandle &Link = N->getLink(i << DS::PointerShift);
486 if (Link.getNode()) {
487 // Compute the offset into the current node at which to
488 // merge this link. In the common case, this is a linear
489 // relation to the offset in the original node (with
490 // wrapping), but if the current node gets collapsed due to
491 // recursive merging, we must make sure to merge in all remaining
492 // links at offset zero.
493 unsigned MergeOffset = 0;
494 DSNode *CN = CurNodeH.getNode();
496 MergeOffset = ((i << DS::PointerShift)+NOffset) % CN->getSize();
497 CN->addEdgeTo(MergeOffset, Link);
501 // Now that there are no outgoing edges, all of the Links are dead.
504 // Merge the globals list...
505 if (!N->Globals.empty()) {
506 MergeSortedVectors(CurNodeH.getNode()->Globals, N->Globals);
508 // Delete the globals from the old node...
509 std::vector<GlobalValue*>().swap(N->Globals);
514 // mergeWith - Merge this node and the specified node, moving all links to and
515 // from the argument node into the current node, deleting the node argument.
516 // Offset indicates what offset the specified node is to be merged into the
519 // The specified node may be a null pointer (in which case, nothing happens).
521 void DSNode::mergeWith(const DSNodeHandle &NH, unsigned Offset) {
522 DSNode *N = NH.getNode();
523 if (N == 0 || (N == this && NH.getOffset() == Offset))
526 assert((N->NodeType & DSNode::DEAD) == 0);
527 assert((NodeType & DSNode::DEAD) == 0);
528 assert(!hasNoReferrers() && "Should not try to fold a useless node!");
531 // We cannot merge two pieces of the same node together, collapse the node
533 DEBUG(std::cerr << "Attempting to merge two chunks of"
534 << " the same node together!\n");
535 foldNodeCompletely();
539 // If both nodes are not at offset 0, make sure that we are merging the node
540 // at an later offset into the node with the zero offset.
542 if (Offset < NH.getOffset()) {
543 N->mergeWith(DSNodeHandle(this, Offset), NH.getOffset());
545 } else if (Offset == NH.getOffset() && getSize() < N->getSize()) {
546 // If the offsets are the same, merge the smaller node into the bigger node
547 N->mergeWith(DSNodeHandle(this, Offset), NH.getOffset());
551 // Ok, now we can merge the two nodes. Use a static helper that works with
552 // two node handles, since "this" may get merged away at intermediate steps.
553 DSNodeHandle CurNodeH(this, Offset);
554 DSNodeHandle NHCopy(NH);
555 DSNode::MergeNodes(CurNodeH, NHCopy);
558 //===----------------------------------------------------------------------===//
559 // DSCallSite Implementation
560 //===----------------------------------------------------------------------===//
562 // Define here to avoid including iOther.h and BasicBlock.h in DSGraph.h
563 Function &DSCallSite::getCaller() const {
564 return *Inst->getParent()->getParent();
568 //===----------------------------------------------------------------------===//
569 // DSGraph Implementation
570 //===----------------------------------------------------------------------===//
572 DSGraph::DSGraph(const DSGraph &G) : Func(G.Func), GlobalsGraph(0) {
573 PrintAuxCalls = false;
574 hash_map<const DSNode*, DSNodeHandle> NodeMap;
575 RetNode = cloneInto(G, ScalarMap, NodeMap);
578 DSGraph::DSGraph(const DSGraph &G,
579 hash_map<const DSNode*, DSNodeHandle> &NodeMap)
580 : Func(G.Func), GlobalsGraph(0) {
581 PrintAuxCalls = false;
582 RetNode = cloneInto(G, ScalarMap, NodeMap);
585 DSGraph::~DSGraph() {
586 FunctionCalls.clear();
587 AuxFunctionCalls.clear();
591 // Drop all intra-node references, so that assertions don't fail...
592 std::for_each(Nodes.begin(), Nodes.end(),
593 std::mem_fun(&DSNode::dropAllReferences));
595 // Delete all of the nodes themselves...
596 std::for_each(Nodes.begin(), Nodes.end(), deleter<DSNode>);
599 // dump - Allow inspection of graph in a debugger.
600 void DSGraph::dump() const { print(std::cerr); }
603 /// remapLinks - Change all of the Links in the current node according to the
604 /// specified mapping.
606 void DSNode::remapLinks(hash_map<const DSNode*, DSNodeHandle> &OldNodeMap) {
607 for (unsigned i = 0, e = Links.size(); i != e; ++i) {
608 DSNodeHandle &H = OldNodeMap[Links[i].getNode()];
609 Links[i].setNode(H.getNode());
610 Links[i].setOffset(Links[i].getOffset()+H.getOffset());
615 // cloneInto - Clone the specified DSGraph into the current graph, returning the
616 // Return node of the graph. The translated ScalarMap for the old function is
617 // filled into the OldValMap member. If StripAllocas is set to true, Alloca
618 // markers are removed from the graph, as the graph is being cloned into a
619 // calling function's graph.
621 DSNodeHandle DSGraph::cloneInto(const DSGraph &G,
622 hash_map<Value*, DSNodeHandle> &OldValMap,
623 hash_map<const DSNode*, DSNodeHandle> &OldNodeMap,
624 unsigned CloneFlags) {
625 assert(OldNodeMap.empty() && "Returned OldNodeMap should be empty!");
626 assert(&G != this && "Cannot clone graph into itself!");
628 unsigned FN = Nodes.size(); // First new node...
630 // Duplicate all of the nodes, populating the node map...
631 Nodes.reserve(FN+G.Nodes.size());
633 // Remove alloca or mod/ref bits as specified...
634 unsigned clearBits = (CloneFlags & StripAllocaBit ? DSNode::AllocaNode : 0)
635 | (CloneFlags & StripModRefBits ? (DSNode::Modified | DSNode::Read) : 0);
636 clearBits |= DSNode::DEAD; // Clear dead flag...
637 for (unsigned i = 0, e = G.Nodes.size(); i != e; ++i) {
638 DSNode *Old = G.Nodes[i];
639 DSNode *New = new DSNode(*Old, this);
640 New->NodeType &= ~clearBits;
641 OldNodeMap[Old] = New;
645 Timer::addPeakMemoryMeasurement();
648 // Rewrite the links in the new nodes to point into the current graph now.
649 for (unsigned i = FN, e = Nodes.size(); i != e; ++i)
650 Nodes[i]->remapLinks(OldNodeMap);
652 // Copy the scalar map... merging all of the global nodes...
653 for (hash_map<Value*, DSNodeHandle>::const_iterator I = G.ScalarMap.begin(),
654 E = G.ScalarMap.end(); I != E; ++I) {
655 DSNodeHandle &H = OldValMap[I->first];
656 DSNodeHandle &MappedNode = OldNodeMap[I->second.getNode()];
657 H.setOffset(I->second.getOffset()+MappedNode.getOffset());
658 H.setNode(MappedNode.getNode());
660 if (isa<GlobalValue>(I->first)) { // Is this a global?
661 hash_map<Value*, DSNodeHandle>::iterator GVI = ScalarMap.find(I->first);
662 if (GVI != ScalarMap.end()) // Is the global value in this fn already?
663 GVI->second.mergeWith(H);
665 ScalarMap[I->first] = H; // Add global pointer to this graph
669 if (!(CloneFlags & DontCloneCallNodes)) {
670 // Copy the function calls list...
671 unsigned FC = FunctionCalls.size(); // FirstCall
672 FunctionCalls.reserve(FC+G.FunctionCalls.size());
673 for (unsigned i = 0, ei = G.FunctionCalls.size(); i != ei; ++i)
674 FunctionCalls.push_back(DSCallSite(G.FunctionCalls[i], OldNodeMap));
677 if (!(CloneFlags & DontCloneAuxCallNodes)) {
678 // Copy the auxillary function calls list...
679 unsigned FC = AuxFunctionCalls.size(); // FirstCall
680 AuxFunctionCalls.reserve(FC+G.AuxFunctionCalls.size());
681 for (unsigned i = 0, ei = G.AuxFunctionCalls.size(); i != ei; ++i)
682 AuxFunctionCalls.push_back(DSCallSite(G.AuxFunctionCalls[i], OldNodeMap));
685 // Return the returned node pointer...
686 DSNodeHandle &MappedRet = OldNodeMap[G.RetNode.getNode()];
687 return DSNodeHandle(MappedRet.getNode(),
688 MappedRet.getOffset()+G.RetNode.getOffset());
691 /// mergeInGraph - The method is used for merging graphs together. If the
692 /// argument graph is not *this, it makes a clone of the specified graph, then
693 /// merges the nodes specified in the call site with the formal arguments in the
696 void DSGraph::mergeInGraph(DSCallSite &CS, const DSGraph &Graph,
697 unsigned CloneFlags) {
698 hash_map<Value*, DSNodeHandle> OldValMap;
700 hash_map<Value*, DSNodeHandle> *ScalarMap = &OldValMap;
702 // If this is not a recursive call, clone the graph into this graph...
703 if (&Graph != this) {
704 // Clone the callee's graph into the current graph, keeping
705 // track of where scalars in the old graph _used_ to point,
706 // and of the new nodes matching nodes of the old graph.
707 hash_map<const DSNode*, DSNodeHandle> OldNodeMap;
709 // The clone call may invalidate any of the vectors in the data
710 // structure graph. Strip locals and don't copy the list of callers
711 RetVal = cloneInto(Graph, OldValMap, OldNodeMap, CloneFlags);
712 ScalarMap = &OldValMap;
714 RetVal = getRetNode();
715 ScalarMap = &getScalarMap();
718 // Merge the return value with the return value of the context...
719 RetVal.mergeWith(CS.getRetVal());
721 // Resolve all of the function arguments...
722 Function &F = Graph.getFunction();
723 Function::aiterator AI = F.abegin();
725 for (unsigned i = 0, e = CS.getNumPtrArgs(); i != e; ++i, ++AI) {
726 // Advance the argument iterator to the first pointer argument...
727 while (AI != F.aend() && !isPointerType(AI->getType())) {
731 std::cerr << "Bad call to Function: " << F.getName() << "\n";
734 if (AI == F.aend()) break;
736 // Add the link from the argument scalar to the provided value
737 assert(ScalarMap->count(AI) && "Argument not in scalar map?");
738 DSNodeHandle &NH = (*ScalarMap)[AI];
739 assert(NH.getNode() && "Pointer argument without scalarmap entry?");
740 NH.mergeWith(CS.getPtrArg(i));
745 // markIncompleteNodes - Mark the specified node as having contents that are not
746 // known with the current analysis we have performed. Because a node makes all
747 // of the nodes it can reach imcomplete if the node itself is incomplete, we
748 // must recursively traverse the data structure graph, marking all reachable
749 // nodes as incomplete.
751 static void markIncompleteNode(DSNode *N) {
752 // Stop recursion if no node, or if node already marked...
753 if (N == 0 || (N->NodeType & DSNode::Incomplete)) return;
755 // Actually mark the node
756 N->NodeType |= DSNode::Incomplete;
758 // Recusively process children...
759 for (unsigned i = 0, e = N->getSize(); i < e; i += DS::PointerSize)
760 if (DSNode *DSN = N->getLink(i).getNode())
761 markIncompleteNode(DSN);
764 static void markIncomplete(DSCallSite &Call) {
765 // Then the return value is certainly incomplete!
766 markIncompleteNode(Call.getRetVal().getNode());
768 // All objects pointed to by function arguments are incomplete!
769 for (unsigned i = 0, e = Call.getNumPtrArgs(); i != e; ++i)
770 markIncompleteNode(Call.getPtrArg(i).getNode());
773 // markIncompleteNodes - Traverse the graph, identifying nodes that may be
774 // modified by other functions that have not been resolved yet. This marks
775 // nodes that are reachable through three sources of "unknownness":
777 // Global Variables, Function Calls, and Incoming Arguments
779 // For any node that may have unknown components (because something outside the
780 // scope of current analysis may have modified it), the 'Incomplete' flag is
781 // added to the NodeType.
783 void DSGraph::markIncompleteNodes(unsigned Flags) {
784 // Mark any incoming arguments as incomplete...
785 if ((Flags & DSGraph::MarkFormalArgs) && Func && Func->getName() != "main")
786 for (Function::aiterator I = Func->abegin(), E = Func->aend(); I != E; ++I)
787 if (isPointerType(I->getType()) && ScalarMap.find(I) != ScalarMap.end())
788 markIncompleteNode(ScalarMap[I].getNode());
790 // Mark stuff passed into functions calls as being incomplete...
791 if (!shouldPrintAuxCalls())
792 for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i)
793 markIncomplete(FunctionCalls[i]);
795 for (unsigned i = 0, e = AuxFunctionCalls.size(); i != e; ++i)
796 markIncomplete(AuxFunctionCalls[i]);
799 // Mark all global nodes as incomplete...
800 if ((Flags & DSGraph::IgnoreGlobals) == 0)
801 for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
802 if (Nodes[i]->NodeType & DSNode::GlobalNode)
803 markIncompleteNode(Nodes[i]);
806 static inline void killIfUselessEdge(DSNodeHandle &Edge) {
807 if (DSNode *N = Edge.getNode()) // Is there an edge?
808 if (N->getNumReferrers() == 1) // Does it point to a lonely node?
809 if ((N->NodeType & ~DSNode::Incomplete) == 0 && // No interesting info?
810 N->getType() == Type::VoidTy && !N->isNodeCompletelyFolded())
811 Edge.setNode(0); // Kill the edge!
814 static inline bool nodeContainsExternalFunction(const DSNode *N) {
815 const std::vector<GlobalValue*> &Globals = N->getGlobals();
816 for (unsigned i = 0, e = Globals.size(); i != e; ++i)
817 if (Globals[i]->isExternal())
822 static void removeIdenticalCalls(std::vector<DSCallSite> &Calls,
823 const std::string &where) {
824 // Remove trivially identical function calls
825 unsigned NumFns = Calls.size();
826 std::sort(Calls.begin(), Calls.end()); // Sort by callee as primary key!
828 // Scan the call list cleaning it up as necessary...
829 DSNode *LastCalleeNode = 0;
830 Function *LastCalleeFunc = 0;
831 unsigned NumDuplicateCalls = 0;
832 bool LastCalleeContainsExternalFunction = false;
833 for (unsigned i = 0; i != Calls.size(); ++i) {
834 DSCallSite &CS = Calls[i];
836 // If the Callee is a useless edge, this must be an unreachable call site,
838 if (CS.isIndirectCall() && CS.getCalleeNode()->getNumReferrers() == 1 &&
839 CS.getCalleeNode()->NodeType == 0) { // No useful info?
840 std::cerr << "WARNING: Useless call site found??\n";
841 CS.swap(Calls.back());
845 // If the return value or any arguments point to a void node with no
846 // information at all in it, and the call node is the only node to point
847 // to it, remove the edge to the node (killing the node).
849 killIfUselessEdge(CS.getRetVal());
850 for (unsigned a = 0, e = CS.getNumPtrArgs(); a != e; ++a)
851 killIfUselessEdge(CS.getPtrArg(a));
853 // If this call site calls the same function as the last call site, and if
854 // the function pointer contains an external function, this node will
855 // never be resolved. Merge the arguments of the call node because no
856 // information will be lost.
858 if ((CS.isDirectCall() && CS.getCalleeFunc() == LastCalleeFunc) ||
859 (CS.isIndirectCall() && CS.getCalleeNode() == LastCalleeNode)) {
861 if (NumDuplicateCalls == 1) {
863 LastCalleeContainsExternalFunction =
864 nodeContainsExternalFunction(LastCalleeNode);
866 LastCalleeContainsExternalFunction = LastCalleeFunc->isExternal();
869 if (LastCalleeContainsExternalFunction ||
870 // This should be more than enough context sensitivity!
871 // FIXME: Evaluate how many times this is tripped!
872 NumDuplicateCalls > 20) {
873 DSCallSite &OCS = Calls[i-1];
876 // The node will now be eliminated as a duplicate!
877 if (CS.getNumPtrArgs() < OCS.getNumPtrArgs())
879 else if (CS.getNumPtrArgs() > OCS.getNumPtrArgs())
883 if (CS.isDirectCall()) {
884 LastCalleeFunc = CS.getCalleeFunc();
887 LastCalleeNode = CS.getCalleeNode();
890 NumDuplicateCalls = 0;
895 Calls.erase(std::unique(Calls.begin(), Calls.end()),
898 // Track the number of call nodes merged away...
899 NumCallNodesMerged += NumFns-Calls.size();
901 DEBUG(if (NumFns != Calls.size())
902 std::cerr << "Merged " << (NumFns-Calls.size())
903 << " call nodes in " << where << "\n";);
907 // removeTriviallyDeadNodes - After the graph has been constructed, this method
908 // removes all unreachable nodes that are created because they got merged with
909 // other nodes in the graph. These nodes will all be trivially unreachable, so
910 // we don't have to perform any non-trivial analysis here.
912 void DSGraph::removeTriviallyDeadNodes() {
913 removeIdenticalCalls(FunctionCalls, Func ? Func->getName() : "");
914 removeIdenticalCalls(AuxFunctionCalls, Func ? Func->getName() : "");
916 for (unsigned i = 0; i != Nodes.size(); ++i) {
917 DSNode *Node = Nodes[i];
918 if (!(Node->NodeType & ~(DSNode::Composition | DSNode::Array |
920 // This is a useless node if it has no mod/ref info (checked above),
921 // outgoing edges (which it cannot, as it is not modified in this
922 // context), and it has no incoming edges. If it is a global node it may
923 // have all of these properties and still have incoming edges, due to the
924 // scalar map, so we check those now.
926 if (Node->getNumReferrers() == Node->getGlobals().size()) {
927 std::vector<GlobalValue*> &Globals = Node->getGlobals();
929 // Loop through and make sure all of the globals are referring directly
931 for (unsigned j = 0, e = Globals.size(); j != e; ++j) {
932 DSNode *N = ScalarMap.find(Globals[j])->second.getNode();
933 assert(N == Node && "ScalarMap doesn't match globals list!");
936 // Make sure numreferrers still agrees, if so, the node is truely dead.
937 if (Node->getNumReferrers() == Globals.size()) {
938 for (unsigned j = 0, e = Globals.size(); j != e; ++j)
939 ScalarMap.erase(Globals[j]);
942 assert(Node->hasNoReferrers() && "Shouldn't have refs now!");
944 Node->NodeType = DSNode::DEAD;
949 if ((Node->NodeType & ~DSNode::DEAD) == 0 && Node->hasNoReferrers()) {
950 // This node is dead!
951 delete Node; // Free memory...
952 Nodes[i--] = Nodes.back();
953 Nodes.pop_back(); // Remove from node list...
959 /// markReachableNodes - This method recursively traverses the specified
960 /// DSNodes, marking any nodes which are reachable. All reachable nodes it adds
961 /// to the set, which allows it to only traverse visited nodes once.
963 void DSNode::markReachableNodes(hash_set<DSNode*> &ReachableNodes) {
964 if (this == 0) return;
965 assert(getForwardNode() == 0 && "Cannot mark a forwarded node!");
966 if (ReachableNodes.count(this)) return; // Already marked reachable
967 ReachableNodes.insert(this); // Is reachable now
969 for (unsigned i = 0, e = getSize(); i < e; i += DS::PointerSize)
970 getLink(i).getNode()->markReachableNodes(ReachableNodes);
973 void DSCallSite::markReachableNodes(hash_set<DSNode*> &Nodes) {
974 getRetVal().getNode()->markReachableNodes(Nodes);
975 if (isIndirectCall()) getCalleeNode()->markReachableNodes(Nodes);
977 for (unsigned i = 0, e = getNumPtrArgs(); i != e; ++i)
978 getPtrArg(i).getNode()->markReachableNodes(Nodes);
981 // CanReachAliveNodes - Simple graph walker that recursively traverses the graph
982 // looking for a node that is marked alive. If an alive node is found, return
983 // true, otherwise return false. If an alive node is reachable, this node is
984 // marked as alive...
986 static bool CanReachAliveNodes(DSNode *N, hash_set<DSNode*> &Alive,
987 hash_set<DSNode*> &Visited) {
988 if (N == 0) return false;
989 assert(N->getForwardNode() == 0 && "Cannot mark a forwarded node!");
991 // If we know that this node is alive, return so!
992 if (Alive.count(N)) return true;
994 // Otherwise, we don't think the node is alive yet, check for infinite
996 if (Visited.count(N)) return false; // Found a cycle
997 Visited.insert(N); // No recursion, insert into Visited...
999 for (unsigned i = 0, e = N->getSize(); i < e; i += DS::PointerSize)
1000 if (CanReachAliveNodes(N->getLink(i).getNode(), Alive, Visited)) {
1001 N->markReachableNodes(Alive);
1007 // CallSiteUsesAliveArgs - Return true if the specified call site can reach any
1010 static bool CallSiteUsesAliveArgs(DSCallSite &CS, hash_set<DSNode*> &Alive,
1011 hash_set<DSNode*> &Visited) {
1012 if (CanReachAliveNodes(CS.getRetVal().getNode(), Alive, Visited))
1014 if (CS.isIndirectCall() &&
1015 CanReachAliveNodes(CS.getCalleeNode(), Alive, Visited))
1017 for (unsigned i = 0, e = CS.getNumPtrArgs(); i != e; ++i)
1018 if (CanReachAliveNodes(CS.getPtrArg(i).getNode(), Alive, Visited))
1023 // removeDeadNodes - Use a more powerful reachability analysis to eliminate
1024 // subgraphs that are unreachable. This often occurs because the data
1025 // structure doesn't "escape" into it's caller, and thus should be eliminated
1026 // from the caller's graph entirely. This is only appropriate to use when
1029 void DSGraph::removeDeadNodes(unsigned Flags) {
1030 // Reduce the amount of work we have to do... remove dummy nodes left over by
1032 removeTriviallyDeadNodes();
1034 // FIXME: Merge nontrivially identical call nodes...
1036 // Alive - a set that holds all nodes found to be reachable/alive.
1037 hash_set<DSNode*> Alive;
1038 std::vector<std::pair<Value*, DSNode*> > GlobalNodes;
1040 // Mark all nodes reachable by (non-global) scalar nodes as alive...
1041 for (hash_map<Value*, DSNodeHandle>::iterator I = ScalarMap.begin(),
1042 E = ScalarMap.end(); I != E; )
1043 if (isa<GlobalValue>(I->first)) { // Keep track of global nodes
1044 assert(I->second.getNode() && "Null global node?");
1045 GlobalNodes.push_back(std::make_pair(I->first, I->second.getNode()));
1048 // Check to see if this is a worthless node generated for non-pointer
1049 // values, such as integers. Consider an addition of long types: A+B.
1050 // Assuming we can track all uses of the value in this context, and it is
1051 // NOT used as a pointer, we can delete the node. We will be able to
1052 // detect this situation if the node pointed to ONLY has Unknown bit set
1053 // in the node. In this case, the node is not incomplete, does not point
1054 // to any other nodes (no mod/ref bits set), and is therefore
1055 // uninteresting for data structure analysis. If we run across one of
1056 // these, prune the scalar pointing to it.
1058 DSNode *N = I->second.getNode();
1059 if (N->NodeType == DSNode::UnknownNode && !isa<Argument>(I->first)) {
1060 ScalarMap.erase(I++);
1062 I->second.getNode()->markReachableNodes(Alive);
1067 // The return value is alive as well...
1068 RetNode.getNode()->markReachableNodes(Alive);
1070 // Mark any nodes reachable by primary calls as alive...
1071 for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i)
1072 FunctionCalls[i].markReachableNodes(Alive);
1075 hash_set<DSNode*> Visited;
1076 std::vector<unsigned char> AuxFCallsAlive(AuxFunctionCalls.size());
1079 // If any global nodes points to a non-global that is "alive", the global is
1080 // "alive" as well... Remove it from the GlobalNodes list so we only have
1081 // unreachable globals in the list.
1084 for (unsigned i = 0; i != GlobalNodes.size(); ++i)
1085 if (CanReachAliveNodes(GlobalNodes[i].second, Alive, Visited)) {
1086 std::swap(GlobalNodes[i--], GlobalNodes.back()); // Move to end to erase
1087 GlobalNodes.pop_back(); // Erase efficiently
1091 for (unsigned i = 0, e = AuxFunctionCalls.size(); i != e; ++i)
1092 if (!AuxFCallsAlive[i] &&
1093 CallSiteUsesAliveArgs(AuxFunctionCalls[i], Alive, Visited)) {
1094 AuxFunctionCalls[i].markReachableNodes(Alive);
1095 AuxFCallsAlive[i] = true;
1100 // Remove all dead aux function calls...
1101 unsigned CurIdx = 0;
1102 for (unsigned i = 0, e = AuxFunctionCalls.size(); i != e; ++i)
1103 if (AuxFCallsAlive[i])
1104 AuxFunctionCalls[CurIdx++].swap(AuxFunctionCalls[i]);
1105 if (!(Flags & DSGraph::RemoveUnreachableGlobals)) {
1106 assert(GlobalsGraph && "No globals graph available??");
1107 // Move the unreachable call nodes to the globals graph...
1108 GlobalsGraph->AuxFunctionCalls.insert(GlobalsGraph->AuxFunctionCalls.end(),
1109 AuxFunctionCalls.begin()+CurIdx,
1110 AuxFunctionCalls.end());
1112 // Crop all the useless ones out...
1113 AuxFunctionCalls.erase(AuxFunctionCalls.begin()+CurIdx,
1114 AuxFunctionCalls.end());
1116 // At this point, any nodes which are visited, but not alive, are nodes which
1117 // should be moved to the globals graph. Loop over all nodes, eliminating
1118 // completely unreachable nodes, and moving visited nodes to the globals graph
1120 std::vector<DSNode*> DeadNodes;
1121 DeadNodes.reserve(Nodes.size());
1122 for (unsigned i = 0; i != Nodes.size(); ++i)
1123 if (!Alive.count(Nodes[i])) {
1124 DSNode *N = Nodes[i];
1125 Nodes[i--] = Nodes.back(); // move node to end of vector
1126 Nodes.pop_back(); // Erase node from alive list.
1127 if (!(Flags & DSGraph::RemoveUnreachableGlobals) && // Not in TD pass
1128 Visited.count(N)) { // Visited but not alive?
1129 GlobalsGraph->Nodes.push_back(N); // Move node to globals graph
1130 N->setParentGraph(GlobalsGraph);
1131 } else { // Otherwise, delete the node
1132 assert(((N->NodeType & DSNode::GlobalNode) == 0 ||
1133 (Flags & DSGraph::RemoveUnreachableGlobals))
1134 && "Killing a global?");
1135 //std::cerr << "[" << i+1 << "/" << DeadNodes.size()
1136 // << "] Node is dead: "; N->dump();
1137 DeadNodes.push_back(N);
1138 N->dropAllReferences();
1141 assert(Nodes[i]->getForwardNode() == 0 && "Alive forwarded node?");
1144 // Now that the nodes have either been deleted or moved to the globals graph,
1145 // loop over the scalarmap, updating the entries for globals...
1147 if (!(Flags & DSGraph::RemoveUnreachableGlobals)) { // Not in the TD pass?
1148 // In this array we start the remapping, which can cause merging. Because
1149 // of this, the DSNode pointers in GlobalNodes may be invalidated, so we
1150 // must always go through the ScalarMap (which contains DSNodeHandles [which
1151 // cannot be invalidated by merging]).
1153 for (unsigned i = 0, e = GlobalNodes.size(); i != e; ++i) {
1154 Value *G = GlobalNodes[i].first;
1155 hash_map<Value*, DSNodeHandle>::iterator I = ScalarMap.find(G);
1156 assert(I != ScalarMap.end() && "Global not in scalar map anymore?");
1157 assert(I->second.getNode() && "Global not pointing to anything?");
1158 assert(!Alive.count(I->second.getNode()) && "Node is alive??");
1159 GlobalsGraph->ScalarMap[G].mergeWith(I->second);
1160 assert(GlobalsGraph->ScalarMap[G].getNode() &&
1161 "Global not pointing to anything?");
1165 // Merging leaves behind silly nodes, we remove them to avoid polluting the
1167 if (!GlobalNodes.empty())
1168 GlobalsGraph->removeTriviallyDeadNodes();
1170 // If we are in the top-down pass, remove all unreachable globals from the
1172 for (unsigned i = 0, e = GlobalNodes.size(); i != e; ++i)
1173 ScalarMap.erase(GlobalNodes[i].first);
1176 // Loop over all of the dead nodes now, deleting them since their referrer
1178 for (unsigned i = 0, e = DeadNodes.size(); i != e; ++i)
1179 delete DeadNodes[i];
1181 DEBUG(AssertGraphOK(); GlobalsGraph->AssertGraphOK());
1184 void DSGraph::AssertGraphOK() const {
1185 for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
1186 Nodes[i]->assertOK();
1187 return; // FIXME: remove
1188 for (hash_map<Value*, DSNodeHandle>::const_iterator I = ScalarMap.begin(),
1189 E = ScalarMap.end(); I != E; ++I) {
1190 assert(I->second.getNode() && "Null node in scalarmap!");
1191 AssertNodeInGraph(I->second.getNode());
1192 if (GlobalValue *GV = dyn_cast<GlobalValue>(I->first)) {
1193 assert((I->second.getNode()->NodeType & DSNode::GlobalNode) &&
1194 "Global points to node, but node isn't global?");
1195 AssertNodeContainsGlobal(I->second.getNode(), GV);
1198 AssertCallNodesInGraph();
1199 AssertAuxCallNodesInGraph();