1 //===- DSSupport.h - Support for datastructure graphs -----------*- C++ -*-===//
3 // Support for graph nodes, call sites, and types.
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 NewNode = 1 << 1, // This node was allocated with malloc
67 GlobalNode = 1 << 2, // This node was allocated by a global var decl
68 Incomplete = 1 << 3, // This node may not be complete
69 Modified = 1 << 4, // This node is modified in this context
70 Read = 1 << 5, // This node is read in this context
73 /// NodeType - A union of the above bits. "Shadow" nodes do not add any flags
74 /// to the nodes in the data structure graph, so it is possible to have nodes
75 /// with a value of 0 for their NodeType. Scalar and Alloca markers go away
76 /// when function graphs are inlined.
78 unsigned char NodeType;
80 DSNode(enum NodeTy NT, const Type *T);
81 DSNode(const DSNode &);
85 dropAllReferences(); // Only needed to satisfy assertion checks...
86 assert(Referrers.empty() && "Referrers to dead node exist!");
90 // Iterator for graph interface...
91 typedef DSNodeIterator iterator;
92 typedef DSNodeIterator const_iterator;
93 inline iterator begin() const; // Defined in DSGraphTraits.h
94 inline iterator end() const;
96 //===--------------------------------------------------
99 /// getSize - Return the maximum number of bytes occupied by this object...
101 unsigned getSize() const { return MergeMap.size(); }
103 // getTypeEntries - Return the possible types and their offsets in this object
104 const std::vector<DSTypeRec> &getTypeEntries() const { return TypeEntries; }
106 /// getReferrers - Return a list of the pointers to this node...
108 const std::vector<DSNodeHandle*> &getReferrers() const { return Referrers; }
110 /// isModified - Return true if this node may be modified in this context
112 bool isModified() const { return (NodeType & Modified) != 0; }
114 /// isRead - Return true if this node may be read in this context
116 bool isRead() const { return (NodeType & Read) != 0; }
119 /// hasLink - Return true if this memory object has a link at the specified
122 bool hasLink(unsigned i) const {
123 assert(i < getSize() && "Field Link index is out of range!");
124 return MergeMap[i] >= 0;
127 DSNodeHandle *getLink(unsigned i) {
129 return &Links[MergeMap[i]];
132 const DSNodeHandle *getLink(unsigned i) const {
134 return &Links[MergeMap[i]];
138 /// getMergeMapLabel - Return the merge map entry specified, to allow printing
139 /// out of DSNodes nicely for DOT graphs.
141 int getMergeMapLabel(unsigned i) const {
142 assert(i < MergeMap.size() && "MergeMap index out of range!");
146 /// getTypeRec - This method returns the specified type record if it exists.
147 /// If it does not yet exist, the method checks to see whether or not the
148 /// request would result in an untrackable state. If adding it would cause
149 /// untrackable state, we foldNodeCompletely the node and return the void
150 /// record, otherwise we add an new TypeEntry and return it.
152 DSTypeRec &getTypeRec(const Type *Ty, unsigned Offset);
154 /// foldNodeCompletely - If we determine that this node has some funny
155 /// behavior happening to it that we cannot represent, we fold it down to a
156 /// single, completely pessimistic, node. This node is represented as a
157 /// single byte with a single TypeEntry of "void".
159 void foldNodeCompletely();
161 /// isNodeCompletelyFolded - Return true if this node has been completely
162 /// folded down to something that can never be expanded, effectively losing
163 /// all of the field sensitivity that may be present in the node.
165 bool isNodeCompletelyFolded() const;
167 /// setLink - Set the link at the specified offset to the specified
168 /// NodeHandle, replacing what was there. It is uncommon to use this method,
169 /// instead one of the higher level methods should be used, below.
171 void setLink(unsigned i, const DSNodeHandle &NH);
173 /// addEdgeTo - Add an edge from the current node to the specified node. This
174 /// can cause merging of nodes in the graph.
176 void addEdgeTo(unsigned Offset, const DSNodeHandle &NH);
178 /// mergeWith - Merge this node and the specified node, moving all links to
179 /// and from the argument node into the current node, deleting the node
180 /// argument. Offset indicates what offset the specified node is to be merged
181 /// into the current node.
183 /// The specified node may be a null pointer (in which case, nothing happens).
185 void mergeWith(const DSNodeHandle &NH, unsigned Offset);
187 /// mergeIndexes - If we discover that two indexes are equivalent and must be
188 /// merged, this function is used to do the dirty work.
190 void mergeIndexes(unsigned idx1, unsigned idx2) {
191 assert(idx1 < getSize() && idx2 < getSize() && "Indexes out of range!");
192 signed char MV1 = MergeMap[idx1];
193 signed char MV2 = MergeMap[idx2];
195 mergeMappedValues(MV1, MV2);
199 /// addGlobal - Add an entry for a global value to the Globals list. This
200 /// also marks the node with the 'G' flag if it does not already have it.
202 void addGlobal(GlobalValue *GV);
203 const std::vector<GlobalValue*> &getGlobals() const { return Globals; }
204 std::vector<GlobalValue*> &getGlobals() { return Globals; }
206 void print(std::ostream &O, const DSGraph *G) const;
209 void dropAllReferences() {
213 /// remapLinks - Change all of the Links in the current node according to the
214 /// specified mapping.
215 void remapLinks(std::map<const DSNode*, DSNode*> &OldNodeMap);
218 friend class DSNodeHandle;
219 // addReferrer - Keep the referrer set up to date...
220 void addReferrer(DSNodeHandle *H) { Referrers.push_back(H); }
221 void removeReferrer(DSNodeHandle *H);
223 /// rewriteMergeMap - Loop over the mergemap, replacing any references to the
224 /// index From to be references to the index To.
226 void rewriteMergeMap(signed char From, signed char To) {
227 assert(From != To && "Cannot change something into itself!");
228 for (unsigned i = 0, e = MergeMap.size(); i != e; ++i)
229 if (MergeMap[i] == From)
233 /// mergeMappedValues - This is the higher level form of rewriteMergeMap. It
234 /// is fully capable of merging links together if neccesary as well as simply
235 /// rewriting the map entries.
237 void mergeMappedValues(signed char V1, signed char V2);
239 /// growNode - Attempt to grow the node to the specified size. This may do
240 /// one of three things:
241 /// 1. Grow the node, return false
242 /// 2. Refuse to grow the node, but maintain a trackable situation, return
244 /// 3. Be unable to track if node was that size, so collapse the node and
247 bool growNode(unsigned RequestedSize);
251 //===----------------------------------------------------------------------===//
252 // Define inline DSNodeHandle functions that depend on the definition of DSNode
255 inline void DSNodeHandle::setNode(DSNode *n) {
256 if (N) N->removeReferrer(this);
258 if (N) N->addReferrer(this);
261 inline bool DSNodeHandle::hasLink(unsigned Num) const {
262 assert(N && "DSNodeHandle does not point to a node yet!");
263 return N->hasLink(Num+Offset);
267 /// getLink - Treat this current node pointer as a pointer to a structure of
268 /// some sort. This method will return the pointer a mem[this+Num]
270 inline const DSNodeHandle *DSNodeHandle::getLink(unsigned Num) const {
271 assert(N && "DSNodeHandle does not point to a node yet!");
272 return N->getLink(Num+Offset);
274 inline DSNodeHandle *DSNodeHandle::getLink(unsigned Num) {
275 assert(N && "DSNodeHandle does not point to a node yet!");
276 return N->getLink(Num+Offset);
279 inline void DSNodeHandle::setLink(unsigned Num, const DSNodeHandle &NH) {
280 assert(N && "DSNodeHandle does not point to a node yet!");
281 N->setLink(Num+Offset, NH);
284 /// addEdgeTo - Add an edge from the current node to the specified node. This
285 /// can cause merging of nodes in the graph.
287 inline void DSNodeHandle::addEdgeTo(unsigned LinkNo, const DSNodeHandle &Node) {
288 assert(N && "DSNodeHandle does not point to a node yet!");
289 N->addEdgeTo(LinkNo+Offset, Node);
292 /// mergeWith - Merge the logical node pointed to by 'this' with the node
293 /// pointed to by 'N'.
295 inline void DSNodeHandle::mergeWith(const DSNodeHandle &Node) {
297 N->mergeWith(Node, Offset);
298 else { // No node to merge with, so just point to Node