1 //===- DSNode.h - Node definition for datastructure graphs ------*- C++ -*-===//
3 // Data structure graph nodes and some implementation of DSNodeHandle.
5 //===----------------------------------------------------------------------===//
7 #ifndef LLVM_ANALYSIS_DSNODE_H
8 #define LLVM_ANALYSIS_DSNODE_H
10 #include "llvm/Analysis/DSSupport.h"
12 //===----------------------------------------------------------------------===//
13 /// DSNode - Data structure node class
15 /// This class represents an untyped memory object of Size bytes. It keeps
16 /// track of any pointers that have been stored into the object as well as the
17 /// different types represented in this object.
20 /// Links - Contains one entry for every _distinct_ pointer field in the
21 /// memory block. These are demand allocated and indexed by the MergeMap
24 std::vector<DSNodeHandle> Links;
26 /// MergeMap - Maps from every byte in the object to a signed byte number.
27 /// This map is neccesary due to the merging that is possible as part of the
28 /// unification algorithm. To merge two distinct bytes of the object together
29 /// into a single logical byte, the indexes for the two bytes are set to the
30 /// same value. This fully general merging is capable of representing all
31 /// manners of array merging if neccesary.
33 /// This map is also used to map outgoing pointers to various byte offsets in
34 /// this data structure node. If this value is >= 0, then it indicates that
35 /// the numbered entry in the Links vector contains the outgoing edge for this
36 /// byte offset. In this way, the Links vector can be demand allocated and
37 /// byte elements of the node may be merged without needing a Link allocated
40 /// Initially, each each element of the MergeMap is assigned a unique negative
41 /// number, which are then merged as the unification occurs.
43 std::vector<signed char> MergeMap;
45 /// Referrers - Keep track of all of the node handles that point to this
46 /// DSNode. These pointers may need to be updated to point to a different
47 /// node if this node gets merged with it.
49 std::vector<DSNodeHandle*> Referrers;
51 /// TypeEntries - As part of the merging process of this algorithm, nodes of
52 /// different types can be represented by this single DSNode. This vector is
55 std::vector<DSTypeRec> TypeEntries;
57 /// Globals - The list of global values that are merged into this node.
59 std::vector<GlobalValue*> Globals;
61 void operator=(const DSNode &); // DO NOT IMPLEMENT
64 ShadowNode = 0, // Nothing is known about this node...
65 AllocaNode = 1 << 0, // This node was allocated with alloca
66 HeapNode = 1 << 1, // This node was allocated with malloc
67 GlobalNode = 1 << 2, // This node was allocated by a global var decl
68 UnknownNode = 1 << 3, // This node points to unknown allocated memory
69 Incomplete = 1 << 4, // This node may not be complete
70 Modified = 1 << 5, // This node is modified in this context
71 Read = 1 << 6, // This node is read in this context
74 /// NodeType - A union of the above bits. "Shadow" nodes do not add any flags
75 /// to the nodes in the data structure graph, so it is possible to have nodes
76 /// with a value of 0 for their NodeType. Scalar and Alloca markers go away
77 /// when function graphs are inlined.
79 unsigned char NodeType;
81 DSNode(enum NodeTy NT, const Type *T);
82 DSNode(const DSNode &);
86 dropAllReferences(); // Only needed to satisfy assertion checks...
87 assert(Referrers.empty() && "Referrers to dead node exist!");
91 // Iterator for graph interface...
92 typedef DSNodeIterator iterator;
93 typedef DSNodeIterator const_iterator;
94 inline iterator begin() const; // Defined in DSGraphTraits.h
95 inline iterator end() const;
97 //===--------------------------------------------------
100 /// getSize - Return the maximum number of bytes occupied by this object...
102 unsigned getSize() const { return MergeMap.size(); }
104 // getTypeEntries - Return the possible types and their offsets in this object
105 const std::vector<DSTypeRec> &getTypeEntries() const { return TypeEntries; }
107 /// getReferrers - Return a list of the pointers to this node...
109 const std::vector<DSNodeHandle*> &getReferrers() const { return Referrers; }
111 /// isModified - Return true if this node may be modified in this context
113 bool isModified() const { return (NodeType & Modified) != 0; }
115 /// isRead - Return true if this node may be read in this context
117 bool isRead() const { return (NodeType & Read) != 0; }
120 /// hasLink - Return true if this memory object has a link at the specified
123 bool hasLink(unsigned i) const {
124 assert(i < getSize() && "Field Link index is out of range!");
125 return MergeMap[i] >= 0;
128 DSNodeHandle *getLink(unsigned i) {
130 assert((unsigned)MergeMap[i] < Links.size() &&
131 "MergeMap references Link that doesn't exist!");
132 return &Links[MergeMap[i]];
136 const DSNodeHandle *getLink(unsigned i) const {
138 assert((unsigned)MergeMap[i] < Links.size() &&
139 "MergeMap references Link that doesn't exist!");
140 return &Links[MergeMap[i]];
145 /// getMergeMapLabel - Return the merge map entry specified, to allow printing
146 /// out of DSNodes nicely for DOT graphs.
148 int getMergeMapLabel(unsigned i) const {
149 assert(i < MergeMap.size() && "MergeMap index out of range!");
153 /// getTypeRec - This method returns the specified type record if it exists.
154 /// If it does not yet exist, the method checks to see whether or not the
155 /// request would result in an untrackable state. If adding it would cause
156 /// untrackable state, we foldNodeCompletely the node and return the void
157 /// record, otherwise we add an new TypeEntry and return it.
159 DSTypeRec &getTypeRec(const Type *Ty, unsigned Offset);
161 /// foldNodeCompletely - If we determine that this node has some funny
162 /// behavior happening to it that we cannot represent, we fold it down to a
163 /// single, completely pessimistic, node. This node is represented as a
164 /// single byte with a single TypeEntry of "void".
166 void foldNodeCompletely();
168 /// isNodeCompletelyFolded - Return true if this node has been completely
169 /// folded down to something that can never be expanded, effectively losing
170 /// all of the field sensitivity that may be present in the node.
172 bool isNodeCompletelyFolded() const;
174 /// setLink - Set the link at the specified offset to the specified
175 /// NodeHandle, replacing what was there. It is uncommon to use this method,
176 /// instead one of the higher level methods should be used, below.
178 void setLink(unsigned i, const DSNodeHandle &NH);
180 /// addEdgeTo - Add an edge from the current node to the specified node. This
181 /// can cause merging of nodes in the graph.
183 void addEdgeTo(unsigned Offset, const DSNodeHandle &NH);
185 /// mergeWith - Merge this node and the specified node, moving all links to
186 /// and from the argument node into the current node, deleting the node
187 /// argument. Offset indicates what offset the specified node is to be merged
188 /// into the current node.
190 /// The specified node may be a null pointer (in which case, nothing happens).
192 void mergeWith(const DSNodeHandle &NH, unsigned Offset);
194 /// mergeIndexes - If we discover that two indexes are equivalent and must be
195 /// merged, this function is used to do the dirty work.
197 void mergeIndexes(unsigned idx1, unsigned idx2) {
198 assert(idx1 < getSize() && idx2 < getSize() && "Indexes out of range!");
199 signed char MV1 = MergeMap[idx1];
200 signed char MV2 = MergeMap[idx2];
202 mergeMappedValues(MV1, MV2);
206 /// addGlobal - Add an entry for a global value to the Globals list. This
207 /// also marks the node with the 'G' flag if it does not already have it.
209 void addGlobal(GlobalValue *GV);
210 const std::vector<GlobalValue*> &getGlobals() const { return Globals; }
211 std::vector<GlobalValue*> &getGlobals() { return Globals; }
213 void print(std::ostream &O, const DSGraph *G) const;
216 void dropAllReferences() {
220 /// remapLinks - Change all of the Links in the current node according to the
221 /// specified mapping.
222 void remapLinks(std::map<const DSNode*, DSNode*> &OldNodeMap);
225 friend class DSNodeHandle;
226 // addReferrer - Keep the referrer set up to date...
227 void addReferrer(DSNodeHandle *H) { Referrers.push_back(H); }
228 void removeReferrer(DSNodeHandle *H);
230 /// rewriteMergeMap - Loop over the mergemap, replacing any references to the
231 /// index From to be references to the index To.
233 void rewriteMergeMap(signed char From, signed char To) {
234 assert(From != To && "Cannot change something into itself!");
235 assert(To < (int)Links.size() &&
236 "Changing MergeMap entry to an illegal entry!");
237 for (unsigned i = 0, e = MergeMap.size(); i != e; ++i)
238 if (MergeMap[i] == From)
242 /// mergeMappedValues - This is the higher level form of rewriteMergeMap. It
243 /// is fully capable of merging links together if neccesary as well as simply
244 /// rewriting the map entries.
246 void mergeMappedValues(signed char V1, signed char V2);
248 /// growNode - Attempt to grow the node to the specified size. This may do
249 /// one of three things:
250 /// 1. Grow the node, return false
251 /// 2. Refuse to grow the node, but maintain a trackable situation, return
253 /// 3. Be unable to track if node was that size, so collapse the node and
256 bool growNode(unsigned RequestedSize);
260 //===----------------------------------------------------------------------===//
261 // Define inline DSNodeHandle functions that depend on the definition of DSNode
264 inline void DSNodeHandle::setNode(DSNode *n) {
265 if (N) N->removeReferrer(this);
267 if (N) N->addReferrer(this);
270 inline bool DSNodeHandle::hasLink(unsigned Num) const {
271 assert(N && "DSNodeHandle does not point to a node yet!");
272 return N->hasLink(Num+Offset);
276 /// getLink - Treat this current node pointer as a pointer to a structure of
277 /// some sort. This method will return the pointer a mem[this+Num]
279 inline const DSNodeHandle *DSNodeHandle::getLink(unsigned Num) const {
280 assert(N && "DSNodeHandle does not point to a node yet!");
281 return N->getLink(Num+Offset);
283 inline DSNodeHandle *DSNodeHandle::getLink(unsigned Num) {
284 assert(N && "DSNodeHandle does not point to a node yet!");
285 return N->getLink(Num+Offset);
288 inline void DSNodeHandle::setLink(unsigned Num, const DSNodeHandle &NH) {
289 assert(N && "DSNodeHandle does not point to a node yet!");
290 N->setLink(Num+Offset, NH);
293 /// addEdgeTo - Add an edge from the current node to the specified node. This
294 /// can cause merging of nodes in the graph.
296 inline void DSNodeHandle::addEdgeTo(unsigned LinkNo, const DSNodeHandle &Node) {
297 assert(N && "DSNodeHandle does not point to a node yet!");
298 N->addEdgeTo(LinkNo+Offset, Node);
301 /// mergeWith - Merge the logical node pointed to by 'this' with the node
302 /// pointed to by 'N'.
304 inline void DSNodeHandle::mergeWith(const DSNodeHandle &Node) {
306 N->mergeWith(Node, Offset);
307 else { // No node to merge with, so just point to Node