1 //===- DSGraph.h - Represent a collection of data structures ----*- C++ -*-===//
3 // This header defines the primative classes that make up a data structure
6 //===----------------------------------------------------------------------===//
8 #ifndef LLVM_ANALYSIS_DSGRAPH_H
9 #define LLVM_ANALYSIS_DSGRAPH_H
21 class DSNode; // Each node in the graph
22 class DSGraph; // A graph for a function
23 class DSNodeIterator; // Data structure graph traversal iterator
26 //===----------------------------------------------------------------------===//
27 /// DSNodeHandle - Implement a "handle" to a data structure node that takes care
28 /// of all of the add/un'refing of the node to prevent the backpointers in the
29 /// graph from getting out of date. This class represents a "pointer" in the
30 /// graph, whose destination is an indexed offset into a node.
36 // Allow construction, destruction, and assignment...
37 DSNodeHandle(DSNode *n = 0, unsigned offs = 0) : N(0), Offset(offs) {
40 DSNodeHandle(const DSNodeHandle &H) : N(0), Offset(H.Offset) { setNode(H.N); }
41 ~DSNodeHandle() { setNode((DSNode*)0); }
42 DSNodeHandle &operator=(const DSNodeHandle &H) {
43 setNode(H.N); Offset = H.Offset;
47 bool operator<(const DSNodeHandle &H) const { // Allow sorting
48 return N < H.N || (N == H.N && Offset < H.Offset);
50 bool operator==(const DSNodeHandle &H) const { // Allow comparison
51 return N == H.N && Offset == H.Offset;
53 bool operator!=(const DSNodeHandle &H) const { return !operator==(H); }
55 // Allow explicit conversion to DSNode...
56 DSNode *getNode() const { return N; }
57 unsigned getOffset() const { return Offset; }
59 inline void setNode(DSNode *N); // Defined inline later...
60 void setOffset(unsigned O) { Offset = O; }
62 void addEdgeTo(unsigned LinkNo, const DSNodeHandle &N);
63 void addEdgeTo(const DSNodeHandle &N) { addEdgeTo(0, N); }
65 /// mergeWith - Merge the logical node pointed to by 'this' with the node
66 /// pointed to by 'N'.
68 void mergeWith(const DSNodeHandle &N);
70 // hasLink - Return true if there is a link at the specified offset...
71 inline bool hasLink(unsigned Num) const;
73 /// getLink - Treat this current node pointer as a pointer to a structure of
74 /// some sort. This method will return the pointer a mem[this+Num]
76 inline const DSNodeHandle *getLink(unsigned Num) const;
77 inline DSNodeHandle *getLink(unsigned Num);
79 inline void setLink(unsigned Num, const DSNodeHandle &NH);
83 //===----------------------------------------------------------------------===//
84 /// DSNode - Data structure node class
86 /// This class represents an untyped memory object of Size bytes. It keeps
87 /// track of any pointers that have been stored into the object as well as the
88 /// different types represented in this object.
91 /// Links - Contains one entry for every _distinct_ pointer field in the
92 /// memory block. These are demand allocated and indexed by the MergeMap
95 std::vector<DSNodeHandle> Links;
97 /// MergeMap - Maps from every byte in the object to a signed byte number.
98 /// This map is neccesary due to the merging that is possible as part of the
99 /// unification algorithm. To merge two distinct bytes of the object together
100 /// into a single logical byte, the indexes for the two bytes are set to the
101 /// same value. This fully general merging is capable of representing all
102 /// manners of array merging if neccesary.
104 /// This map is also used to map outgoing pointers to various byte offsets in
105 /// this data structure node. If this value is >= 0, then it indicates that
106 /// the numbered entry in the Links vector contains the outgoing edge for this
107 /// byte offset. In this way, the Links vector can be demand allocated and
108 /// byte elements of the node may be merged without needing a Link allocated
111 /// Initially, each each element of the MergeMap is assigned a unique negative
112 /// number, which are then merged as the unification occurs.
114 std::vector<signed char> MergeMap;
116 /// Referrers - Keep track of all of the node handles that point to this
117 /// DSNode. These pointers may need to be updated to point to a different
118 /// node if this node gets merged with it.
120 std::vector<DSNodeHandle*> Referrers;
122 /// TypeEntries - As part of the merging process of this algorithm, nodes of
123 /// different types can be represented by this single DSNode. This vector is
130 TypeRec() : Ty(0), Offset(0) {}
131 TypeRec(const Type *T, unsigned O) : Ty(T), Offset(O) {}
133 bool operator<(const TypeRec &TR) const {
134 // Sort first by offset!
135 return Offset < TR.Offset || (Offset == TR.Offset && Ty < TR.Ty);
137 bool operator==(const TypeRec &TR) const {
138 return Ty == TR.Ty && Offset == TR.Offset;
140 bool operator!=(const TypeRec &TR) const { return !operator==(TR); }
143 std::vector<TypeRec> TypeEntries;
145 /// Globals - The list of global values that are merged into this node.
147 std::vector<GlobalValue*> Globals;
149 void operator=(const DSNode &); // DO NOT IMPLEMENT
152 ShadowNode = 0, // Nothing is known about this node...
153 ScalarNode = 1 << 0, // Scalar of the current function contains this value
154 AllocaNode = 1 << 1, // This node was allocated with alloca
155 NewNode = 1 << 2, // This node was allocated with malloc
156 GlobalNode = 1 << 3, // This node was allocated by a global var decl
157 Incomplete = 1 << 4, // This node may not be complete
158 Modified = 1 << 5, // This node is modified in this context
159 Read = 1 << 6, // This node is read in this context
162 /// NodeType - A union of the above bits. "Shadow" nodes do not add any flags
163 /// to the nodes in the data structure graph, so it is possible to have nodes
164 /// with a value of 0 for their NodeType. Scalar and Alloca markers go away
165 /// when function graphs are inlined.
167 unsigned char NodeType;
169 DSNode(enum NodeTy NT, const Type *T);
170 DSNode(const DSNode &);
174 dropAllReferences(); // Only needed to satisfy assertion checks...
175 assert(Referrers.empty() && "Referrers to dead node exist!");
179 // Iterator for graph interface...
180 typedef DSNodeIterator iterator;
181 typedef DSNodeIterator const_iterator;
182 inline iterator begin() const; // Defined in DSGraphTraits.h
183 inline iterator end() const;
185 //===--------------------------------------------------
188 /// getSize - Return the maximum number of bytes occupied by this object...
190 unsigned getSize() const { return MergeMap.size(); }
192 // getTypeEntries - Return the possible types and their offsets in this object
193 const std::vector<TypeRec> &getTypeEntries() const { return TypeEntries; }
195 /// getReferrers - Return a list of the pointers to this node...
197 const std::vector<DSNodeHandle*> &getReferrers() const { return Referrers; }
199 /// isModified - Return true if this node may be modified in this context
201 bool isModified() const { return (NodeType & Modified) != 0; }
203 /// isRead - Return true if this node may be read in this context
205 bool isRead() const { return (NodeType & Read) != 0; }
208 /// hasLink - Return true if this memory object has a link at the specified
211 bool hasLink(unsigned i) const {
212 assert(i < getSize() && "Field Link index is out of range!");
213 return MergeMap[i] >= 0;
216 DSNodeHandle *getLink(unsigned i) {
218 return &Links[MergeMap[i]];
221 const DSNodeHandle *getLink(unsigned i) const {
223 return &Links[MergeMap[i]];
227 int getMergeMapLabel(unsigned i) const {
228 assert(i < MergeMap.size() && "MergeMap index out of range!");
232 /// setLink - Set the link at the specified offset to the specified
233 /// NodeHandle, replacing what was there. It is uncommon to use this method,
234 /// instead one of the higher level methods should be used, below.
236 void setLink(unsigned i, const DSNodeHandle &NH);
238 /// addEdgeTo - Add an edge from the current node to the specified node. This
239 /// can cause merging of nodes in the graph.
241 void addEdgeTo(unsigned Offset, const DSNodeHandle &NH);
243 /// mergeWith - Merge this node and the specified node, moving all links to
244 /// and from the argument node into the current node, deleting the node
245 /// argument. Offset indicates what offset the specified node is to be merged
246 /// into the current node.
248 /// The specified node may be a null pointer (in which case, nothing happens).
250 void mergeWith(const DSNodeHandle &NH, unsigned Offset);
252 /// mergeIndexes - If we discover that two indexes are equivalent and must be
253 /// merged, this function is used to do the dirty work.
255 void mergeIndexes(unsigned idx1, unsigned idx2) {
256 assert(idx1 < getSize() && idx2 < getSize() && "Indexes out of range!");
257 signed char MV1 = MergeMap[idx1];
258 signed char MV2 = MergeMap[idx2];
260 mergeMappedValues(MV1, MV2);
264 /// addGlobal - Add an entry for a global value to the Globals list. This
265 /// also marks the node with the 'G' flag if it does not already have it.
267 void addGlobal(GlobalValue *GV);
268 const std::vector<GlobalValue*> &getGlobals() const { return Globals; }
269 std::vector<GlobalValue*> &getGlobals() { return Globals; }
271 void print(std::ostream &O, const DSGraph *G) const;
274 void dropAllReferences() {
278 /// remapLinks - Change all of the Links in the current node according to the
279 /// specified mapping.
280 void remapLinks(std::map<const DSNode*, DSNode*> &OldNodeMap);
283 friend class DSNodeHandle;
284 // addReferrer - Keep the referrer set up to date...
285 void addReferrer(DSNodeHandle *H) { Referrers.push_back(H); }
286 void removeReferrer(DSNodeHandle *H);
288 /// rewriteMergeMap - Loop over the mergemap, replacing any references to the
289 /// index From to be references to the index To.
291 void rewriteMergeMap(signed char From, signed char To) {
292 assert(From != To && "Cannot change something into itself!");
293 for (unsigned i = 0, e = MergeMap.size(); i != e; ++i)
294 if (MergeMap[i] == From)
298 /// mergeMappedValues - This is the higher level form of rewriteMergeMap. It
299 /// is fully capable of merging links together if neccesary as well as simply
300 /// rewriting the map entries.
302 void mergeMappedValues(signed char V1, signed char V2);
306 //===----------------------------------------------------------------------===//
307 // Define inline DSNodeHandle functions that depend on the definition of DSNode
310 inline void DSNodeHandle::setNode(DSNode *n) {
311 if (N) N->removeReferrer(this);
313 if (N) N->addReferrer(this);
316 inline bool DSNodeHandle::hasLink(unsigned Num) const {
317 assert(N && "DSNodeHandle does not point to a node yet!");
318 return N->hasLink(Num+Offset);
322 /// getLink - Treat this current node pointer as a pointer to a structure of
323 /// some sort. This method will return the pointer a mem[this+Num]
325 inline const DSNodeHandle *DSNodeHandle::getLink(unsigned Num) const {
326 assert(N && "DSNodeHandle does not point to a node yet!");
327 return N->getLink(Num+Offset);
329 inline DSNodeHandle *DSNodeHandle::getLink(unsigned Num) {
330 assert(N && "DSNodeHandle does not point to a node yet!");
331 return N->getLink(Num+Offset);
334 inline void DSNodeHandle::setLink(unsigned Num, const DSNodeHandle &NH) {
335 assert(N && "DSNodeHandle does not point to a node yet!");
336 N->setLink(Num+Offset, NH);
339 /// addEdgeTo - Add an edge from the current node to the specified node. This
340 /// can cause merging of nodes in the graph.
342 inline void DSNodeHandle::addEdgeTo(unsigned LinkNo, const DSNodeHandle &Node) {
343 assert(N && "DSNodeHandle does not point to a node yet!");
344 N->addEdgeTo(LinkNo+Offset, Node);
347 /// mergeWith - Merge the logical node pointed to by 'this' with the node
348 /// pointed to by 'N'.
350 inline void DSNodeHandle::mergeWith(const DSNodeHandle &Node) {
351 assert(N && "DSNodeHandle does not point to a node yet!");
352 N->mergeWith(Node, Offset);
356 //===----------------------------------------------------------------------===//
357 /// DSCallSite - Representation of a call site via its call instruction,
358 /// the DSNode handle for the callee function (or function pointer), and
359 /// the DSNode handles for the function arguments.
361 class DSCallSite: public std::vector<DSNodeHandle> {
364 DSCallSite(); // do not implement
367 DSCallSite(Function& _caller, CallInst& _callInst)
368 : caller(&_caller), callInst(&_callInst) { }
370 // Copy constructor with helper for cloning nodes. The helper should be a
371 // model of unary_function<const DSNodeHandle*, DSNodeHandle>, i.e., it
372 // should take a pointer to DSNodeHandle and return a fresh DSNodeHandle.
373 // If no helper is specified, this defaults to a simple copy constructor.
374 template<typename _CopierFunction>
375 DSCallSite::DSCallSite(const DSCallSite& FromCall,
376 _CopierFunction nodeCopier = *(_CopierFunction*) 0);
378 Function& getCaller() const { return *caller; }
379 CallInst& getCallInst() const { return *callInst; }
380 DSNodeHandle getReturnValueNode() const { return (*this)[0]; }
381 DSNodeHandle getCalleeNode() const { return (*this)[1]; }
385 //===----------------------------------------------------------------------===//
386 /// DSGraph - The graph that represents a function.
390 std::vector<DSNode*> Nodes;
391 DSNodeHandle RetNode; // Node that gets returned...
392 std::map<Value*, DSNodeHandle> ValueMap;
395 // GlobalsGraph -- Reference to the common graph of globally visible objects.
396 // This includes GlobalValues, New nodes, Cast nodes, and Calls.
398 GlobalDSGraph* GlobalsGraph;
401 // FunctionCalls - This vector maintains a single entry for each call
402 // instruction in the current graph. Each call entry contains DSNodeHandles
403 // that refer to the arguments that are passed into the function call. The
404 // first entry in the vector is the scalar that holds the return value for the
405 // call, the second is the function scalar being invoked, and the rest are
406 // pointer arguments to the function.
408 std::vector<DSCallSite> FunctionCalls;
410 void operator=(const DSGraph &); // DO NOT IMPLEMENT
412 DSGraph() : Func(0) {} // Create a new, empty, DSGraph.
413 DSGraph(Function &F); // Compute the local DSGraph
414 DSGraph(const DSGraph &DSG); // Copy ctor
417 bool hasFunction() const { return Func != 0; }
418 Function &getFunction() const { return *Func; }
420 /// getNodes - Get a vector of all the nodes in the graph
422 const std::vector<DSNode*> &getNodes() const { return Nodes; }
423 std::vector<DSNode*> &getNodes() { return Nodes; }
425 /// addNode - Add a new node to the graph.
427 void addNode(DSNode *N) { Nodes.push_back(N); }
429 /// getValueMap - Get a map that describes what the nodes the scalars in this
430 /// function point to...
432 std::map<Value*, DSNodeHandle> &getValueMap() { return ValueMap; }
433 const std::map<Value*, DSNodeHandle> &getValueMap() const { return ValueMap;}
435 std::vector<DSCallSite> &getFunctionCalls() {
436 return FunctionCalls;
438 const std::vector<DSCallSite> &getFunctionCalls() const {
439 return FunctionCalls;
442 /// getNodeForValue - Given a value that is used or defined in the body of the
443 /// current function, return the DSNode that it points to.
445 DSNodeHandle &getNodeForValue(Value *V) { return ValueMap[V]; }
447 const DSNodeHandle &getRetNode() const { return RetNode; }
448 DSNodeHandle &getRetNode() { return RetNode; }
450 unsigned getGraphSize() const {
454 void print(std::ostream &O) const;
456 void writeGraphToFile(std::ostream &O, const std::string &GraphName) const;
458 // maskNodeTypes - Apply a mask to all of the node types in the graph. This
459 // is useful for clearing out markers like Scalar or Incomplete.
461 void maskNodeTypes(unsigned char Mask);
462 void maskIncompleteMarkers() { maskNodeTypes(~DSNode::Incomplete); }
464 // markIncompleteNodes - Traverse the graph, identifying nodes that may be
465 // modified by other functions that have not been resolved yet. This marks
466 // nodes that are reachable through three sources of "unknownness":
467 // Global Variables, Function Calls, and Incoming Arguments
469 // For any node that may have unknown components (because something outside
470 // the scope of current analysis may have modified it), the 'Incomplete' flag
471 // is added to the NodeType.
473 void markIncompleteNodes(bool markFormalArgs = true);
475 // removeTriviallyDeadNodes - After the graph has been constructed, this
476 // method removes all unreachable nodes that are created because they got
477 // merged with other nodes in the graph.
479 void removeTriviallyDeadNodes(bool KeepAllGlobals = false);
481 // removeDeadNodes - Use a more powerful reachability analysis to eliminate
482 // subgraphs that are unreachable. This often occurs because the data
483 // structure doesn't "escape" into it's caller, and thus should be eliminated
484 // from the caller's graph entirely. This is only appropriate to use when
487 void removeDeadNodes(bool KeepAllGlobals = false, bool KeepCalls = true);
489 // cloneInto - Clone the specified DSGraph into the current graph, returning
490 // the Return node of the graph. The translated ValueMap for the old function
491 // is filled into the OldValMap member.
492 // If StripScalars (StripAllocas) is set to true, Scalar (Alloca) markers
493 // are removed from the graph as the graph is being cloned.
494 // If CopyCallers is set to true, the PendingCallers list is copied.
495 // If CopyOrigCalls is set to true, the OrigFunctionCalls list is copied.
497 DSNodeHandle cloneInto(const DSGraph &G,
498 std::map<Value*, DSNodeHandle> &OldValMap,
499 std::map<const DSNode*, DSNode*> &OldNodeMap,
500 bool StripScalars = false, bool StripAllocas = false,
501 bool CopyCallers = true, bool CopyOrigCalls = true);
504 // cloneGlobalInto - Clone the given global node (or the node for the given
505 // GlobalValue) from the GlobalsGraph and all its target links (recursively).
507 DSNode* cloneGlobalInto(const DSNode* GNode);
508 DSNode* cloneGlobalInto(GlobalValue* GV) {
509 assert(!GV || (((DSGraph*) GlobalsGraph)->ValueMap[GV] != 0));
510 return GV? cloneGlobalInto(((DSGraph*) GlobalsGraph)->ValueMap[GV]) : 0;
515 bool isNodeDead(DSNode *N);