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
19 class DSNode; // Each node in the graph
20 class DSGraph; // A graph for a function
21 class DSNodeIterator; // Data structure graph traversal iterator
23 //===----------------------------------------------------------------------===//
24 /// DSNodeHandle - Implement a "handle" to a data structure node that takes care
25 /// of all of the add/un'refing of the node to prevent the backpointers in the
26 /// graph from getting out of date. This class represents a "pointer" in the
27 /// graph, whose destination is an indexed offset into a node.
33 // Allow construction, destruction, and assignment...
34 DSNodeHandle(DSNode *n = 0, unsigned offs = 0) : N(0), Offset(offs) {
37 DSNodeHandle(const DSNodeHandle &H) : N(0), Offset(H.Offset) { setNode(H.N); }
38 ~DSNodeHandle() { setNode((DSNode*)0); }
39 DSNodeHandle &operator=(const DSNodeHandle &H) {
40 setNode(H.N); Offset = H.Offset;
44 bool operator<(const DSNodeHandle &H) const { // Allow sorting
45 return N < H.N || (N == H.N && Offset < H.Offset);
47 bool operator==(const DSNodeHandle &H) const { // Allow comparison
48 return N == H.N && Offset == H.Offset;
50 bool operator!=(const DSNodeHandle &H) const { return !operator==(H); }
52 // Allow explicit conversion to DSNode...
53 DSNode *getNode() const { return N; }
54 unsigned getOffset() const { return Offset; }
56 inline void setNode(DSNode *N); // Defined inline later...
57 void setOffset(unsigned O) { Offset = O; }
59 void addEdgeTo(unsigned LinkNo, const DSNodeHandle &N);
60 void addEdgeTo(const DSNodeHandle &N) { addEdgeTo(0, N); }
62 /// mergeWith - Merge the logical node pointed to by 'this' with the node
63 /// pointed to by 'N'.
65 void mergeWith(const DSNodeHandle &N);
67 // hasLink - Return true if there is a link at the specified offset...
68 inline bool hasLink(unsigned Num) const;
70 /// getLink - Treat this current node pointer as a pointer to a structure of
71 /// some sort. This method will return the pointer a mem[this+Num]
73 inline const DSNodeHandle *getLink(unsigned Num) const;
74 inline DSNodeHandle *getLink(unsigned Num);
76 inline void setLink(unsigned Num, const DSNodeHandle &NH);
80 //===----------------------------------------------------------------------===//
81 /// DSNode - Data structure node class
83 /// This class represents an untyped memory object of Size bytes. It keeps
84 /// track of any pointers that have been stored into the object as well as the
85 /// different types represented in this object.
88 /// Links - Contains one entry for every _distinct_ pointer field in the
89 /// memory block. These are demand allocated and indexed by the MergeMap
92 std::vector<DSNodeHandle> Links;
94 /// MergeMap - Maps from every byte in the object to a signed byte number.
95 /// This map is neccesary due to the merging that is possible as part of the
96 /// unification algorithm. To merge two distinct bytes of the object together
97 /// into a single logical byte, the indexes for the two bytes are set to the
98 /// same value. This fully general merging is capable of representing all
99 /// manners of array merging if neccesary.
101 /// This map is also used to map outgoing pointers to various byte offsets in
102 /// this data structure node. If this value is >= 0, then it indicates that
103 /// the numbered entry in the Links vector contains the outgoing edge for this
104 /// byte offset. In this way, the Links vector can be demand allocated and
105 /// byte elements of the node may be merged without needing a Link allocated
108 /// Initially, each each element of the MergeMap is assigned a unique negative
109 /// number, which are then merged as the unification occurs.
111 std::vector<signed char> MergeMap;
113 /// Referrers - Keep track of all of the node handles that point to this
114 /// DSNode. These pointers may need to be updated to point to a different
115 /// node if this node gets merged with it.
117 std::vector<DSNodeHandle*> Referrers;
119 /// TypeEntries - As part of the merging process of this algorithm, nodes of
120 /// different types can be represented by this single DSNode. This vector is
123 typedef std::pair<const Type *, unsigned> TypeRec;
124 std::vector<TypeRec> TypeEntries;
126 /// Globals - The list of global values that are merged into this node.
128 std::vector<GlobalValue*> Globals;
130 void operator=(const DSNode &); // DO NOT IMPLEMENT
133 ShadowNode = 0, // Nothing is known about this node...
134 ScalarNode = 1 << 0, // Scalar of the current function contains this value
135 AllocaNode = 1 << 1, // This node was allocated with alloca
136 NewNode = 1 << 2, // This node was allocated with malloc
137 GlobalNode = 1 << 3, // This node was allocated by a global var decl
138 Incomplete = 1 << 4, // This node may not be complete
141 /// NodeType - A union of the above bits. "Shadow" nodes do not add any flags
142 /// to the nodes in the data structure graph, so it is possible to have nodes
143 /// with a value of 0 for their NodeType. Scalar and Alloca markers go away
144 /// when function graphs are inlined.
146 unsigned char NodeType;
148 DSNode(enum NodeTy NT, const Type *T);
149 DSNode(const DSNode &);
153 dropAllReferences(); // Only needed to satisfy assertion checks...
154 assert(Referrers.empty() && "Referrers to dead node exist!");
158 // Iterator for graph interface...
159 typedef DSNodeIterator iterator;
160 typedef DSNodeIterator const_iterator;
161 inline iterator begin() const; // Defined in DSGraphTraits.h
162 inline iterator end() const;
164 //===--------------------------------------------------
167 // getSize - Return the maximum number of bytes occupied by this object...
168 unsigned getSize() const { return MergeMap.size(); }
170 // getTypeEntries - Return the possible types and their offsets in this object
171 const std::vector<TypeRec> &getTypeEntries() const { return TypeEntries; }
173 // getReferrers - Return a list of the pointers to this node...
174 const std::vector<DSNodeHandle*> &getReferrers() const { return Referrers; }
177 /// hasLink - Return true if this memory object has a link at the specified
180 bool hasLink(unsigned i) const {
181 assert(i < getSize() && "Field Link index is out of range!");
182 return MergeMap[i] >= 0;
185 DSNodeHandle *getLink(unsigned i) {
187 return &Links[MergeMap[i]];
190 const DSNodeHandle *getLink(unsigned i) const {
192 return &Links[MergeMap[i]];
196 int getMergeMapLabel(unsigned i) const {
197 assert(i < MergeMap.size() && "MergeMap index out of range!");
201 /// setLink - Set the link at the specified offset to the specified
202 /// NodeHandle, replacing what was there. It is uncommon to use this method,
203 /// instead one of the higher level methods should be used, below.
205 void setLink(unsigned i, const DSNodeHandle &NH);
207 /// addEdgeTo - Add an edge from the current node to the specified node. This
208 /// can cause merging of nodes in the graph.
210 void addEdgeTo(unsigned Offset, const DSNodeHandle &NH);
212 /// mergeWith - Merge this node and the specified node, moving all links to
213 /// and from the argument node into the current node, deleting the node
214 /// argument. Offset indicates what offset the specified node is to be merged
215 /// into the current node.
217 /// The specified node may be a null pointer (in which case, nothing happens).
219 void mergeWith(const DSNodeHandle &NH, unsigned Offset);
221 /// mergeIndexes - If we discover that two indexes are equivalent and must be
222 /// merged, this function is used to do the dirty work.
224 void mergeIndexes(unsigned idx1, unsigned idx2) {
225 assert(idx1 < getSize() && idx2 < getSize() && "Indexes out of range!");
226 signed char MV1 = MergeMap[idx1];
227 signed char MV2 = MergeMap[idx2];
229 mergeMappedValues(MV1, MV2);
233 /// addGlobal - Add an entry for a global value to the Globals list. This
234 /// also marks the node with the 'G' flag if it does not already have it.
236 void addGlobal(GlobalValue *GV);
237 const std::vector<GlobalValue*> &getGlobals() const { return Globals; }
238 std::vector<GlobalValue*> &getGlobals() { return Globals; }
240 void print(std::ostream &O, const DSGraph *G) const;
243 void dropAllReferences() {
247 /// remapLinks - Change all of the Links in the current node according to the
248 /// specified mapping.
249 void remapLinks(std::map<const DSNode*, DSNode*> &OldNodeMap);
252 friend class DSNodeHandle;
253 // addReferrer - Keep the referrer set up to date...
254 void addReferrer(DSNodeHandle *H) { Referrers.push_back(H); }
255 void removeReferrer(DSNodeHandle *H);
257 /// rewriteMergeMap - Loop over the mergemap, replacing any references to the
258 /// index From to be references to the index To.
260 void rewriteMergeMap(signed char From, signed char To) {
261 assert(From != To && "Cannot change something into itself!");
262 for (unsigned i = 0, e = MergeMap.size(); i != e; ++i)
263 if (MergeMap[i] == From)
267 /// mergeMappedValues - This is the higher level form of rewriteMergeMap. It
268 /// is fully capable of merging links together if neccesary as well as simply
269 /// rewriting the map entries.
271 void mergeMappedValues(signed char V1, signed char V2);
275 //===----------------------------------------------------------------------===//
276 // Define inline DSNodeHandle functions that depend on the definition of DSNode
279 inline void DSNodeHandle::setNode(DSNode *n) {
280 if (N) N->removeReferrer(this);
282 if (N) N->addReferrer(this);
285 inline bool DSNodeHandle::hasLink(unsigned Num) const {
286 assert(N && "DSNodeHandle does not point to a node yet!");
287 return N->hasLink(Num+Offset);
291 /// getLink - Treat this current node pointer as a pointer to a structure of
292 /// some sort. This method will return the pointer a mem[this+Num]
294 inline const DSNodeHandle *DSNodeHandle::getLink(unsigned Num) const {
295 assert(N && "DSNodeHandle does not point to a node yet!");
296 return N->getLink(Num+Offset);
298 inline DSNodeHandle *DSNodeHandle::getLink(unsigned Num) {
299 assert(N && "DSNodeHandle does not point to a node yet!");
300 return N->getLink(Num+Offset);
303 inline void DSNodeHandle::setLink(unsigned Num, const DSNodeHandle &NH) {
304 assert(N && "DSNodeHandle does not point to a node yet!");
305 N->setLink(Num+Offset, NH);
308 /// addEdgeTo - Add an edge from the current node to the specified node. This
309 /// can cause merging of nodes in the graph.
311 inline void DSNodeHandle::addEdgeTo(unsigned LinkNo, const DSNodeHandle &Node) {
312 assert(N && "DSNodeHandle does not point to a node yet!");
313 N->addEdgeTo(LinkNo+Offset, Node);
316 /// mergeWith - Merge the logical node pointed to by 'this' with the node
317 /// pointed to by 'N'.
319 inline void DSNodeHandle::mergeWith(const DSNodeHandle &Node) {
320 assert(N && "DSNodeHandle does not point to a node yet!");
321 N->mergeWith(Node, Offset);
325 //===----------------------------------------------------------------------===//
326 /// DSGraph - The graph that represents a function.
330 std::vector<DSNode*> Nodes;
331 DSNodeHandle RetNode; // Node that gets returned...
332 std::map<Value*, DSNodeHandle> ValueMap;
335 // GlobalsGraph -- Reference to the common graph of globally visible objects.
336 // This includes GlobalValues, New nodes, Cast nodes, and Calls.
338 GlobalDSGraph* GlobalsGraph;
341 // FunctionCalls - This vector maintains a single entry for each call
342 // instruction in the current graph. Each call entry contains DSNodeHandles
343 // that refer to the arguments that are passed into the function call. The
344 // first entry in the vector is the scalar that holds the return value for the
345 // call, the second is the function scalar being invoked, and the rest are
346 // pointer arguments to the function.
348 std::vector<std::vector<DSNodeHandle> > FunctionCalls;
350 void operator=(const DSGraph &); // DO NOT IMPLEMENT
352 DSGraph() : Func(0) {} // Create a new, empty, DSGraph.
353 DSGraph(Function &F); // Compute the local DSGraph
354 DSGraph(const DSGraph &DSG); // Copy ctor
357 bool hasFunction() const { return Func != 0; }
358 Function &getFunction() const { return *Func; }
360 /// getNodes - Get a vector of all the nodes in the graph
362 const std::vector<DSNode*> &getNodes() const { return Nodes; }
363 std::vector<DSNode*> &getNodes() { return Nodes; }
365 /// addNode - Add a new node to the graph.
367 void addNode(DSNode *N) { Nodes.push_back(N); }
369 /// getValueMap - Get a map that describes what the nodes the scalars in this
370 /// function point to...
372 std::map<Value*, DSNodeHandle> &getValueMap() { return ValueMap; }
373 const std::map<Value*, DSNodeHandle> &getValueMap() const { return ValueMap;}
375 std::vector<std::vector<DSNodeHandle> > &getFunctionCalls() {
376 return FunctionCalls;
378 const std::vector<std::vector<DSNodeHandle> > &getFunctionCalls() const {
379 return FunctionCalls;
382 /// getNodeForValue - Given a value that is used or defined in the body of the
383 /// current function, return the DSNode that it points to.
385 DSNodeHandle &getNodeForValue(Value *V) { return ValueMap[V]; }
387 const DSNodeHandle &getRetNode() const { return RetNode; }
388 DSNodeHandle &getRetNode() { return RetNode; }
390 unsigned getGraphSize() const {
394 void print(std::ostream &O) const;
396 void writeGraphToFile(std::ostream &O, const std::string &GraphName) const;
398 // maskNodeTypes - Apply a mask to all of the node types in the graph. This
399 // is useful for clearing out markers like Scalar or Incomplete.
401 void maskNodeTypes(unsigned char Mask);
402 void maskIncompleteMarkers() { maskNodeTypes(~DSNode::Incomplete); }
404 // markIncompleteNodes - Traverse the graph, identifying nodes that may be
405 // modified by other functions that have not been resolved yet. This marks
406 // nodes that are reachable through three sources of "unknownness":
407 // Global Variables, Function Calls, and Incoming Arguments
409 // For any node that may have unknown components (because something outside
410 // the scope of current analysis may have modified it), the 'Incomplete' flag
411 // is added to the NodeType.
413 void markIncompleteNodes(bool markFormalArgs = true);
415 // removeTriviallyDeadNodes - After the graph has been constructed, this
416 // method removes all unreachable nodes that are created because they got
417 // merged with other nodes in the graph.
419 void removeTriviallyDeadNodes(bool KeepAllGlobals = false);
421 // removeDeadNodes - Use a more powerful reachability analysis to eliminate
422 // subgraphs that are unreachable. This often occurs because the data
423 // structure doesn't "escape" into it's caller, and thus should be eliminated
424 // from the caller's graph entirely. This is only appropriate to use when
427 void removeDeadNodes(bool KeepAllGlobals = false, bool KeepCalls = true);
429 // cloneInto - Clone the specified DSGraph into the current graph, returning
430 // the Return node of the graph. The translated ValueMap for the old function
431 // is filled into the OldValMap member.
432 // If StripScalars (StripAllocas) is set to true, Scalar (Alloca) markers
433 // are removed from the graph as the graph is being cloned.
434 // If CopyCallers is set to true, the PendingCallers list is copied.
435 // If CopyOrigCalls is set to true, the OrigFunctionCalls list is copied.
437 DSNodeHandle cloneInto(const DSGraph &G,
438 std::map<Value*, DSNodeHandle> &OldValMap,
439 std::map<const DSNode*, DSNode*> &OldNodeMap,
440 bool StripScalars = false, bool StripAllocas = false,
441 bool CopyCallers = true, bool CopyOrigCalls = true);
444 // cloneGlobalInto - Clone the given global node (or the node for the given
445 // GlobalValue) from the GlobalsGraph and all its target links (recursively).
447 DSNode* cloneGlobalInto(const DSNode* GNode);
448 DSNode* cloneGlobalInto(GlobalValue* GV) {
449 assert(!GV || (((DSGraph*) GlobalsGraph)->ValueMap[GV] != 0));
450 return GV? cloneGlobalInto(((DSGraph*) GlobalsGraph)->ValueMap[GV]) : 0;
455 bool isNodeDead(DSNode *N);