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29 /// graph from getting out of date.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 /// TypeRec - This structure is used to represent a single type that is held
125 const Type *Ty; // The type itself...
126 unsigned Offset; // The offset in the node
127 bool isArray; // Have we accessed an array of elements?
129 TypeRec() : Ty(0), Offset(0) {}
130 TypeRec(const Type *T, unsigned O) : Ty(T), Offset(O) {}
132 bool operator<(const TypeRec &TR) const {
133 // Sort first by offset!
134 return Offset < TR.Offset || (Offset == TR.Offset && Ty < TR.Ty);
136 bool operator==(const TypeRec &TR) const {
137 return Ty == TR.Ty && Offset == TR.Offset;
139 bool operator!=(const TypeRec &TR) const { return !operator==(TR); }
142 /// TypeEntries - As part of the merging process of this algorithm, nodes of
143 /// different types can be represented by this single DSNode. This vector is
146 std::vector<TypeRec> TypeEntries;
148 /// Globals - The list of global values that are merged into this node.
150 std::vector<GlobalValue*> Globals;
152 void operator=(const DSNode &); // DO NOT IMPLEMENT
155 ShadowNode = 0, // Nothing is known about this node...
156 ScalarNode = 1 << 0, // Scalar of the current function contains this value
157 AllocaNode = 1 << 1, // This node was allocated with alloca
158 NewNode = 1 << 2, // This node was allocated with malloc
159 GlobalNode = 1 << 3, // This node was allocated by a global var decl
160 Incomplete = 1 << 4, // This node may not be complete
161 Modified = 1 << 5, // This node is modified in this context
162 Read = 1 << 6, // This node is read in this context
165 /// NodeType - A union of the above bits. "Shadow" nodes do not add any flags
166 /// to the nodes in the data structure graph, so it is possible to have nodes
167 /// with a value of 0 for their NodeType. Scalar and Alloca markers go away
168 /// when function graphs are inlined.
170 unsigned char NodeType;
172 DSNode(enum NodeTy NT, const Type *T);
173 DSNode(const DSNode &);
177 dropAllReferences(); // Only needed to satisfy assertion checks...
178 assert(Referrers.empty() && "Referrers to dead node exist!");
182 // Iterator for graph interface...
183 typedef DSNodeIterator iterator;
184 typedef DSNodeIterator const_iterator;
185 inline iterator begin() const; // Defined in DSGraphTraits.h
186 inline iterator end() const;
188 //===--------------------------------------------------
191 /// getSize - Return the maximum number of bytes occupied by this object...
193 unsigned getSize() const { return MergeMap.size(); }
195 // getTypeEntries - Return the possible types and their offsets in this object
196 const std::vector<TypeRec> &getTypeEntries() const { return TypeEntries; }
198 /// getReferrers - Return a list of the pointers to this node...
200 const std::vector<DSNodeHandle*> &getReferrers() const { return Referrers; }
202 /// isModified - Return true if this node may be modified in this context
204 bool isModified() const { return (NodeType & Modified) != 0; }
206 /// isRead - Return true if this node may be read in this context
208 bool isRead() const { return (NodeType & Read) != 0; }
211 /// hasLink - Return true if this memory object has a link at the specified
214 bool hasLink(unsigned i) const {
215 assert(i < getSize() && "Field Link index is out of range!");
216 return MergeMap[i] >= 0;
219 DSNodeHandle *getLink(unsigned i) {
221 return &Links[MergeMap[i]];
224 const DSNodeHandle *getLink(unsigned i) const {
226 return &Links[MergeMap[i]];
230 int getMergeMapLabel(unsigned i) const {
231 assert(i < MergeMap.size() && "MergeMap index out of range!");
235 /// setLink - Set the link at the specified offset to the specified
236 /// NodeHandle, replacing what was there. It is uncommon to use this method,
237 /// instead one of the higher level methods should be used, below.
239 void setLink(unsigned i, const DSNodeHandle &NH);
241 /// addEdgeTo - Add an edge from the current node to the specified node. This
242 /// can cause merging of nodes in the graph.
244 void addEdgeTo(unsigned Offset, const DSNodeHandle &NH);
246 /// mergeWith - Merge this node and the specified node, moving all links to
247 /// and from the argument node into the current node, deleting the node
248 /// argument. Offset indicates what offset the specified node is to be merged
249 /// into the current node.
251 /// The specified node may be a null pointer (in which case, nothing happens).
253 void mergeWith(const DSNodeHandle &NH, unsigned Offset);
255 /// mergeIndexes - If we discover that two indexes are equivalent and must be
256 /// merged, this function is used to do the dirty work.
258 void mergeIndexes(unsigned idx1, unsigned idx2) {
259 assert(idx1 < getSize() && idx2 < getSize() && "Indexes out of range!");
260 signed char MV1 = MergeMap[idx1];
261 signed char MV2 = MergeMap[idx2];
263 mergeMappedValues(MV1, MV2);
267 /// addGlobal - Add an entry for a global value to the Globals list. This
268 /// also marks the node with the 'G' flag if it does not already have it.
270 void addGlobal(GlobalValue *GV);
271 const std::vector<GlobalValue*> &getGlobals() const { return Globals; }
272 std::vector<GlobalValue*> &getGlobals() { return Globals; }
274 void print(std::ostream &O, const DSGraph *G) const;
277 void dropAllReferences() {
281 /// remapLinks - Change all of the Links in the current node according to the
282 /// specified mapping.
283 void remapLinks(std::map<const DSNode*, DSNode*> &OldNodeMap);
286 friend class DSNodeHandle;
287 // addReferrer - Keep the referrer set up to date...
288 void addReferrer(DSNodeHandle *H) { Referrers.push_back(H); }
289 void removeReferrer(DSNodeHandle *H);
291 /// rewriteMergeMap - Loop over the mergemap, replacing any references to the
292 /// index From to be references to the index To.
294 void rewriteMergeMap(signed char From, signed char To) {
295 assert(From != To && "Cannot change something into itself!");
296 for (unsigned i = 0, e = MergeMap.size(); i != e; ++i)
297 if (MergeMap[i] == From)
301 /// mergeMappedValues - This is the higher level form of rewriteMergeMap. It
302 /// is fully capable of merging links together if neccesary as well as simply
303 /// rewriting the map entries.
305 void mergeMappedValues(signed char V1, signed char V2);
309 //===----------------------------------------------------------------------===//
310 // Define inline DSNodeHandle functions that depend on the definition of DSNode
313 inline void DSNodeHandle::setNode(DSNode *n) {
314 if (N) N->removeReferrer(this);
316 if (N) N->addReferrer(this);
319 inline bool DSNodeHandle::hasLink(unsigned Num) const {
320 assert(N && "DSNodeHandle does not point to a node yet!");
321 return N->hasLink(Num+Offset);
325 /// getLink - Treat this current node pointer as a pointer to a structure of
326 /// some sort. This method will return the pointer a mem[this+Num]
328 inline const DSNodeHandle *DSNodeHandle::getLink(unsigned Num) const {
329 assert(N && "DSNodeHandle does not point to a node yet!");
330 return N->getLink(Num+Offset);
332 inline DSNodeHandle *DSNodeHandle::getLink(unsigned Num) {
333 assert(N && "DSNodeHandle does not point to a node yet!");
334 return N->getLink(Num+Offset);
337 inline void DSNodeHandle::setLink(unsigned Num, const DSNodeHandle &NH) {
338 assert(N && "DSNodeHandle does not point to a node yet!");
339 N->setLink(Num+Offset, NH);
342 /// addEdgeTo - Add an edge from the current node to the specified node. This
343 /// can cause merging of nodes in the graph.
345 inline void DSNodeHandle::addEdgeTo(unsigned LinkNo, const DSNodeHandle &Node) {
346 assert(N && "DSNodeHandle does not point to a node yet!");
347 N->addEdgeTo(LinkNo+Offset, Node);
350 /// mergeWith - Merge the logical node pointed to by 'this' with the node
351 /// pointed to by 'N'.
353 inline void DSNodeHandle::mergeWith(const DSNodeHandle &Node) {
354 assert(N && "DSNodeHandle does not point to a node yet!");
355 N->mergeWith(Node, Offset);
359 //===----------------------------------------------------------------------===//
360 /// DSCallSite - Representation of a call site via its call instruction,
361 /// the DSNode handle for the callee function (or function pointer), and
362 /// the DSNode handles for the function arguments.
364 class DSCallSite: public std::vector<DSNodeHandle> {
366 DSCallSite(); // do not implement
369 DSCallSite(CallInst& _callInst) : callInst(&_callInst) { }
371 // Copy constructor with helper for cloning nodes. The helper should be a
372 // model of unary_function<const DSNodeHandle*, DSNodeHandle>, i.e., it
373 // should take a pointer to DSNodeHandle and return a fresh DSNodeHandle.
374 // If no helper is specified, this defaults to a simple copy constructor.
375 template<typename _CopierFunction>
376 DSCallSite(const DSCallSite& FromCall,
377 _CopierFunction nodeCopier = *(_CopierFunction*) 0);
379 Function& getCaller() const;
380 CallInst& getCallInst() const { return *callInst; }
381 DSNodeHandle getReturnValueNode() const { return (*this)[0]; }
382 DSNodeHandle getCalleeNode() const { return (*this)[1]; }
383 unsigned getNumPtrArgs() const { return (size() - 2); }
384 DSNodeHandle getPtrArgNode(unsigned i) const { assert(i < getNumPtrArgs());
385 return (*this)[i+2]; }
389 //===----------------------------------------------------------------------===//
390 /// DSGraph - The graph that represents a function.
394 std::vector<DSNode*> Nodes;
395 DSNodeHandle RetNode; // Node that gets returned...
396 std::map<Value*, DSNodeHandle> ValueMap;
399 // GlobalsGraph -- Reference to the common graph of globally visible objects.
400 // This includes GlobalValues, New nodes, Cast nodes, and Calls.
402 GlobalDSGraph* GlobalsGraph;
405 // FunctionCalls - This vector maintains a single entry for each call
406 // instruction in the current graph. Each call entry contains DSNodeHandles
407 // that refer to the arguments that are passed into the function call. The
408 // first entry in the vector is the scalar that holds the return value for the
409 // call, the second is the function scalar being invoked, and the rest are
410 // pointer arguments to the function.
412 std::vector<DSCallSite> FunctionCalls;
414 void operator=(const DSGraph &); // DO NOT IMPLEMENT
416 DSGraph() : Func(0) {} // Create a new, empty, DSGraph.
417 DSGraph(Function &F); // Compute the local DSGraph
418 DSGraph(const DSGraph &DSG); // Copy ctor
421 bool hasFunction() const { return Func != 0; }
422 Function &getFunction() const { return *Func; }
424 /// getNodes - Get a vector of all the nodes in the graph
426 const std::vector<DSNode*> &getNodes() const { return Nodes; }
427 std::vector<DSNode*> &getNodes() { return Nodes; }
429 /// addNode - Add a new node to the graph.
431 void addNode(DSNode *N) { Nodes.push_back(N); }
433 /// getValueMap - Get a map that describes what the nodes the scalars in this
434 /// function point to...
436 std::map<Value*, DSNodeHandle> &getValueMap() { return ValueMap; }
437 const std::map<Value*, DSNodeHandle> &getValueMap() const { return ValueMap;}
439 std::vector<DSCallSite> &getFunctionCalls() {
440 return FunctionCalls;
442 const std::vector<DSCallSite> &getFunctionCalls() const {
443 return FunctionCalls;
446 /// getNodeForValue - Given a value that is used or defined in the body of the
447 /// current function, return the DSNode that it points to.
449 DSNodeHandle &getNodeForValue(Value *V) { return ValueMap[V]; }
451 const DSNodeHandle &getRetNode() const { return RetNode; }
452 DSNodeHandle &getRetNode() { return RetNode; }
454 unsigned getGraphSize() const {
458 void print(std::ostream &O) const;
460 void writeGraphToFile(std::ostream &O, const std::string &GraphName) const;
462 // maskNodeTypes - Apply a mask to all of the node types in the graph. This
463 // is useful for clearing out markers like Scalar or Incomplete.
465 void maskNodeTypes(unsigned char Mask);
466 void maskIncompleteMarkers() { maskNodeTypes(~DSNode::Incomplete); }
468 // markIncompleteNodes - Traverse the graph, identifying nodes that may be
469 // modified by other functions that have not been resolved yet. This marks
470 // nodes that are reachable through three sources of "unknownness":
471 // Global Variables, Function Calls, and Incoming Arguments
473 // For any node that may have unknown components (because something outside
474 // the scope of current analysis may have modified it), the 'Incomplete' flag
475 // is added to the NodeType.
477 void markIncompleteNodes(bool markFormalArgs = true);
479 // removeTriviallyDeadNodes - After the graph has been constructed, this
480 // method removes all unreachable nodes that are created because they got
481 // merged with other nodes in the graph.
483 void removeTriviallyDeadNodes(bool KeepAllGlobals = false);
485 // removeDeadNodes - Use a more powerful reachability analysis to eliminate
486 // subgraphs that are unreachable. This often occurs because the data
487 // structure doesn't "escape" into it's caller, and thus should be eliminated
488 // from the caller's graph entirely. This is only appropriate to use when
491 void removeDeadNodes(bool KeepAllGlobals = false, bool KeepCalls = true);
493 // cloneInto - Clone the specified DSGraph into the current graph, returning
494 // the Return node of the graph. The translated ValueMap for the old function
495 // is filled into the OldValMap member.
496 // If StripScalars (StripAllocas) is set to true, Scalar (Alloca) markers
497 // are removed from the graph as the graph is being cloned.
498 // If CopyCallers is set to true, the PendingCallers list is copied.
499 // If CopyOrigCalls is set to true, the OrigFunctionCalls list is copied.
501 DSNodeHandle cloneInto(const DSGraph &G,
502 std::map<Value*, DSNodeHandle> &OldValMap,
503 std::map<const DSNode*, DSNode*> &OldNodeMap,
504 bool StripScalars = false, bool StripAllocas = false,
505 bool CopyCallers = true, bool CopyOrigCalls = true);
508 // cloneGlobalInto - Clone the given global node (or the node for the given
509 // GlobalValue) from the GlobalsGraph and all its target links (recursively).
511 DSNode* cloneGlobalInto(const DSNode* GNode);
512 DSNode* cloneGlobalInto(GlobalValue* GV) {
513 assert(!GV || (((DSGraph*) GlobalsGraph)->ValueMap[GV] != 0));
514 return GV? cloneGlobalInto(((DSGraph*) GlobalsGraph)->ValueMap[GV]) : 0;
519 bool isNodeDead(DSNode *N);