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DSGraph.h

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00001 //===- DSGraph.h - Represent a collection of data structures ----*- C++ -*-===//
00002 // 
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by the LLVM research group and is distributed under
00006 // the University of Illinois Open Source License. See LICENSE.TXT for details.
00007 // 
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This header defines the data structure graph (DSGraph) and the
00011 // ReachabilityCloner class.
00012 //
00013 //===----------------------------------------------------------------------===//
00014 
00015 #ifndef LLVM_ANALYSIS_DSGRAPH_H
00016 #define LLVM_ANALYSIS_DSGRAPH_H
00017 
00018 #include "llvm/Analysis/DataStructure/DSNode.h"
00019 
00020 namespace llvm {
00021 
00022 class GlobalValue;
00023 
00024 //===----------------------------------------------------------------------===//
00025 /// DSScalarMap - An instance of this class is used to keep track of all of 
00026 /// which DSNode each scalar in a function points to.  This is specialized to
00027 /// keep track of globals with nodes in the function, and to keep track of the 
00028 /// unique DSNodeHandle being used by the scalar map.
00029 ///
00030 /// This class is crucial to the efficiency of DSA with some large SCC's.  In 
00031 /// these cases, the cost of iterating over the scalar map dominates the cost
00032 /// of DSA.  In all of these cases, the DSA phase is really trying to identify 
00033 /// globals or unique node handles active in the function.
00034 ///
00035 class DSScalarMap {
00036   typedef hash_map<Value*, DSNodeHandle> ValueMapTy;
00037   ValueMapTy ValueMap;
00038 
00039   typedef hash_set<GlobalValue*> GlobalSetTy;
00040   GlobalSetTy GlobalSet;
00041 public:
00042 
00043   // Compatibility methods: provide an interface compatible with a map of 
00044   // Value* to DSNodeHandle's.
00045   typedef ValueMapTy::const_iterator const_iterator;
00046   typedef ValueMapTy::iterator iterator;
00047   iterator begin() { return ValueMap.begin(); }
00048   iterator end()   { return ValueMap.end(); }
00049   const_iterator begin() const { return ValueMap.begin(); }
00050   const_iterator end() const { return ValueMap.end(); }
00051   iterator find(Value *V) { return ValueMap.find(V); }
00052   const_iterator find(Value *V) const { return ValueMap.find(V); }
00053   unsigned count(Value *V) const { return ValueMap.count(V); }
00054 
00055   void erase(Value *V) { erase(find(V)); }
00056 
00057   /// replaceScalar - When an instruction needs to be modified, this method can
00058   /// be used to update the scalar map to remove the old and insert the new.
00059   ///
00060   void replaceScalar(Value *Old, Value *New) {
00061     iterator I = find(Old);
00062     assert(I != end() && "Old value is not in the map!");
00063     ValueMap.insert(std::make_pair(New, I->second));
00064     erase(I);
00065   }
00066 
00067   DSNodeHandle &operator[](Value *V) {
00068     std::pair<iterator,bool> IP = 
00069       ValueMap.insert(std::make_pair(V, DSNodeHandle()));
00070     if (IP.second) {  // Inserted the new entry into the map.
00071       if (GlobalValue *GV = dyn_cast<GlobalValue>(V))
00072         GlobalSet.insert(GV);
00073     }
00074     return IP.first->second;
00075   }
00076 
00077   void erase(iterator I) { 
00078     assert(I != ValueMap.end() && "Cannot erase end!");
00079     if (GlobalValue *GV = dyn_cast<GlobalValue>(I->first))
00080       GlobalSet.erase(GV);
00081     ValueMap.erase(I); 
00082   }
00083 
00084   void clear() {
00085     ValueMap.clear();
00086     GlobalSet.clear();
00087   }
00088 
00089   // Access to the global set: the set of all globals currently in the
00090   // scalar map.
00091   typedef GlobalSetTy::const_iterator global_iterator;
00092   global_iterator global_begin() const { return GlobalSet.begin(); }
00093   global_iterator global_end() const { return GlobalSet.end(); }
00094 };
00095 
00096 
00097 //===----------------------------------------------------------------------===//
00098 /// DSGraph - The graph that represents a function.
00099 ///
00100 struct DSGraph {
00101   // Public data-type declarations...
00102   typedef DSScalarMap ScalarMapTy;
00103   typedef hash_map<Function*, DSNodeHandle> ReturnNodesTy;
00104   typedef hash_set<GlobalValue*> GlobalSetTy;
00105   typedef ilist<DSNode> NodeListTy;
00106 
00107   /// NodeMapTy - This data type is used when cloning one graph into another to
00108   /// keep track of the correspondence between the nodes in the old and new
00109   /// graphs.
00110   typedef hash_map<const DSNode*, DSNodeHandle> NodeMapTy;
00111 private:
00112   DSGraph *GlobalsGraph;   // Pointer to the common graph of global objects
00113   bool PrintAuxCalls;      // Should this graph print the Aux calls vector?
00114 
00115   NodeListTy Nodes;
00116   ScalarMapTy ScalarMap;
00117 
00118   // ReturnNodes - A return value for every function merged into this graph.
00119   // Each DSGraph may have multiple functions merged into it at any time, which
00120   // is used for representing SCCs.
00121   //
00122   ReturnNodesTy ReturnNodes;
00123 
00124   // FunctionCalls - This vector maintains a single entry for each call
00125   // instruction in the current graph.  The first entry in the vector is the
00126   // scalar that holds the return value for the call, the second is the function
00127   // scalar being invoked, and the rest are pointer arguments to the function.
00128   // This vector is built by the Local graph and is never modified after that.
00129   //
00130   std::vector<DSCallSite> FunctionCalls;
00131 
00132   // AuxFunctionCalls - This vector contains call sites that have been processed
00133   // by some mechanism.  In pratice, the BU Analysis uses this vector to hold
00134   // the _unresolved_ call sites, because it cannot modify FunctionCalls.
00135   //
00136   std::vector<DSCallSite> AuxFunctionCalls;
00137 
00138   // InlinedGlobals - This set records which globals have been inlined from
00139   // other graphs (callers or callees, depending on the pass) into this one.
00140   // 
00141   GlobalSetTy InlinedGlobals;
00142 
00143   /// TD - This is the target data object for the machine this graph is
00144   /// constructed for.
00145   const TargetData &TD;
00146 
00147   void operator=(const DSGraph &); // DO NOT IMPLEMENT
00148 
00149 public:
00150   // Create a new, empty, DSGraph.
00151   DSGraph(const TargetData &td)
00152     : GlobalsGraph(0), PrintAuxCalls(false), TD(td) {}
00153 
00154   // Compute the local DSGraph
00155   DSGraph(const TargetData &td, Function &F, DSGraph *GlobalsGraph);
00156 
00157   // Copy ctor - If you want to capture the node mapping between the source and
00158   // destination graph, you may optionally do this by specifying a map to record
00159   // this into.
00160   //
00161   // Note that a copied graph does not retain the GlobalsGraph pointer of the
00162   // source.  You need to set a new GlobalsGraph with the setGlobalsGraph
00163   // method.
00164   //
00165   DSGraph(const DSGraph &DSG);
00166   DSGraph(const DSGraph &DSG, NodeMapTy &NodeMap);
00167   ~DSGraph();
00168 
00169   DSGraph *getGlobalsGraph() const { return GlobalsGraph; }
00170   void setGlobalsGraph(DSGraph *G) { GlobalsGraph = G; }
00171 
00172   /// getTargetData - Return the TargetData object for the current target.
00173   ///
00174   const TargetData &getTargetData() const { return TD; }
00175 
00176   /// setPrintAuxCalls - If you call this method, the auxillary call vector will
00177   /// be printed instead of the standard call vector to the dot file.
00178   ///
00179   void setPrintAuxCalls() { PrintAuxCalls = true; }
00180   bool shouldPrintAuxCalls() const { return PrintAuxCalls; }
00181 
00182   /// node_iterator/begin/end - Iterate over all of the nodes in the graph.  Be
00183   /// extremely careful with these methods because any merging of nodes could
00184   /// cause the node to be removed from this list.  This means that if you are
00185   /// iterating over nodes and doing something that could cause _any_ node to
00186   /// merge, your node_iterators into this graph can be invalidated.
00187   typedef NodeListTy::compat_iterator node_iterator;
00188   node_iterator node_begin() const { return Nodes.compat_begin(); }
00189   node_iterator node_end()   const { return Nodes.compat_end(); }
00190 
00191   /// getFunctionNames - Return a space separated list of the name of the
00192   /// functions in this graph (if any)
00193   ///
00194   std::string getFunctionNames() const;
00195 
00196   /// addNode - Add a new node to the graph.
00197   ///
00198   void addNode(DSNode *N) { Nodes.push_back(N); }
00199   void unlinkNode(DSNode *N) { Nodes.remove(N); }
00200 
00201   /// getScalarMap - Get a map that describes what the nodes the scalars in this
00202   /// function point to...
00203   ///
00204   ScalarMapTy &getScalarMap() { return ScalarMap; }
00205   const ScalarMapTy &getScalarMap() const { return ScalarMap; }
00206 
00207   /// getFunctionCalls - Return the list of call sites in the original local
00208   /// graph...
00209   ///
00210   const std::vector<DSCallSite> &getFunctionCalls() const {
00211     return FunctionCalls;
00212   }
00213 
00214   /// getAuxFunctionCalls - Get the call sites as modified by whatever passes
00215   /// have been run.
00216   ///
00217   std::vector<DSCallSite> &getAuxFunctionCalls() {
00218     return AuxFunctionCalls;
00219   }
00220   const std::vector<DSCallSite> &getAuxFunctionCalls() const {
00221     return AuxFunctionCalls;
00222   }
00223 
00224   /// getInlinedGlobals - Get the set of globals that are have been inlined
00225   /// (from callees in BU or from callers in TD) into the current graph.
00226   ///
00227   GlobalSetTy& getInlinedGlobals() {
00228     return InlinedGlobals;
00229   }
00230 
00231   /// getNodeForValue - Given a value that is used or defined in the body of the
00232   /// current function, return the DSNode that it points to.
00233   ///
00234   DSNodeHandle &getNodeForValue(Value *V) { return ScalarMap[V]; }
00235 
00236   const DSNodeHandle &getNodeForValue(Value *V) const {
00237     ScalarMapTy::const_iterator I = ScalarMap.find(V);
00238     assert(I != ScalarMap.end() &&
00239            "Use non-const lookup function if node may not be in the map");
00240     return I->second;
00241   }
00242 
00243   /// getReturnNodes - Return the mapping of functions to their return nodes for
00244   /// this graph.
00245   ///
00246   const ReturnNodesTy &getReturnNodes() const { return ReturnNodes; }
00247         ReturnNodesTy &getReturnNodes()       { return ReturnNodes; }
00248 
00249   /// getReturnNodeFor - Return the return node for the specified function.
00250   ///
00251   DSNodeHandle &getReturnNodeFor(Function &F) {
00252     ReturnNodesTy::iterator I = ReturnNodes.find(&F);
00253     assert(I != ReturnNodes.end() && "F not in this DSGraph!");
00254     return I->second;
00255   }
00256 
00257   const DSNodeHandle &getReturnNodeFor(Function &F) const {
00258     ReturnNodesTy::const_iterator I = ReturnNodes.find(&F);
00259     assert(I != ReturnNodes.end() && "F not in this DSGraph!");
00260     return I->second;
00261   }
00262 
00263   /// getGraphSize - Return the number of nodes in this graph.
00264   ///
00265   unsigned getGraphSize() const {
00266     return Nodes.size();
00267   }
00268 
00269   /// print - Print a dot graph to the specified ostream...
00270   ///
00271   void print(std::ostream &O) const;
00272 
00273   /// dump - call print(std::cerr), for use from the debugger...
00274   ///
00275   void dump() const;
00276 
00277   /// viewGraph - Emit a dot graph, run 'dot', run gv on the postscript file,
00278   /// then cleanup.  For use from the debugger.
00279   ///
00280   void viewGraph() const;
00281 
00282   void writeGraphToFile(std::ostream &O, const std::string &GraphName) const;
00283 
00284   /// maskNodeTypes - Apply a mask to all of the node types in the graph.  This
00285   /// is useful for clearing out markers like Incomplete.
00286   ///
00287   void maskNodeTypes(unsigned Mask) {
00288     for (node_iterator I = node_begin(), E = node_end(); I != E; ++I)
00289       (*I)->maskNodeTypes(Mask);
00290   }
00291   void maskIncompleteMarkers() { maskNodeTypes(~DSNode::Incomplete); }
00292 
00293   // markIncompleteNodes - Traverse the graph, identifying nodes that may be
00294   // modified by other functions that have not been resolved yet.  This marks
00295   // nodes that are reachable through three sources of "unknownness":
00296   //   Global Variables, Function Calls, and Incoming Arguments
00297   //
00298   // For any node that may have unknown components (because something outside
00299   // the scope of current analysis may have modified it), the 'Incomplete' flag
00300   // is added to the NodeType.
00301   //
00302   enum MarkIncompleteFlags {
00303     MarkFormalArgs = 1, IgnoreFormalArgs = 0,
00304     IgnoreGlobals = 2, MarkGlobalsIncomplete = 0,
00305   };
00306   void markIncompleteNodes(unsigned Flags);
00307 
00308   // removeDeadNodes - Use a reachability analysis to eliminate subgraphs that
00309   // are unreachable.  This often occurs because the data structure doesn't
00310   // "escape" into it's caller, and thus should be eliminated from the caller's
00311   // graph entirely.  This is only appropriate to use when inlining graphs.
00312   //
00313   enum RemoveDeadNodesFlags {
00314     RemoveUnreachableGlobals = 1, KeepUnreachableGlobals = 0,
00315   };
00316   void removeDeadNodes(unsigned Flags);
00317 
00318   /// CloneFlags enum - Bits that may be passed into the cloneInto method to
00319   /// specify how to clone the function graph.
00320   enum CloneFlags {
00321     StripAllocaBit        = 1 << 0, KeepAllocaBit     = 0,
00322     DontCloneCallNodes    = 1 << 1, CloneCallNodes    = 0,
00323     DontCloneAuxCallNodes = 1 << 2, CloneAuxCallNodes = 0,
00324     StripModRefBits       = 1 << 3, KeepModRefBits    = 0,
00325     StripIncompleteBit    = 1 << 4, KeepIncompleteBit = 0,
00326     UpdateInlinedGlobals  = 1 << 5, DontUpdateInlinedGlobals = 0,
00327   };
00328 
00329   void updateFromGlobalGraph();
00330 
00331   /// computeNodeMapping - Given roots in two different DSGraphs, traverse the
00332   /// nodes reachable from the two graphs, computing the mapping of nodes from
00333   /// the first to the second graph.
00334   ///
00335   static void computeNodeMapping(const DSNodeHandle &NH1,
00336                                  const DSNodeHandle &NH2, NodeMapTy &NodeMap,
00337                                  bool StrictChecking = true);
00338 
00339 
00340   /// cloneInto - Clone the specified DSGraph into the current graph.  The
00341   /// translated ScalarMap for the old function is filled into the OldValMap
00342   /// member, and the translated ReturnNodes map is returned into ReturnNodes.
00343   /// OldNodeMap contains a mapping from the original nodes to the newly cloned
00344   /// nodes.
00345   ///
00346   /// The CloneFlags member controls various aspects of the cloning process.
00347   ///
00348   void cloneInto(const DSGraph &G, ScalarMapTy &OldValMap,
00349                  ReturnNodesTy &OldReturnNodes, NodeMapTy &OldNodeMap,
00350                  unsigned CloneFlags = 0);
00351 
00352   /// mergeInGraph - The method is used for merging graphs together.  If the
00353   /// argument graph is not *this, it makes a clone of the specified graph, then
00354   /// merges the nodes specified in the call site with the formal arguments in
00355   /// the graph.  If the StripAlloca's argument is 'StripAllocaBit' then Alloca
00356   /// markers are removed from nodes.
00357   ///
00358   void mergeInGraph(const DSCallSite &CS, Function &F, const DSGraph &Graph,
00359                     unsigned CloneFlags);
00360 
00361   /// getCallSiteForArguments - Get the arguments and return value bindings for
00362   /// the specified function in the current graph.
00363   ///
00364   DSCallSite getCallSiteForArguments(Function &F) const;
00365 
00366   /// getDSCallSiteForCallSite - Given an LLVM CallSite object that is live in
00367   /// the context of this graph, return the DSCallSite for it.
00368   DSCallSite getDSCallSiteForCallSite(CallSite CS) const;
00369 
00370   // Methods for checking to make sure graphs are well formed...
00371   void AssertNodeInGraph(const DSNode *N) const {
00372     assert((!N || N->getParentGraph() == this) &&
00373            "AssertNodeInGraph: Node is not in graph!");
00374   }
00375   void AssertNodeContainsGlobal(const DSNode *N, GlobalValue *GV) const {
00376     assert(std::find(N->getGlobals().begin(), N->getGlobals().end(), GV) !=
00377            N->getGlobals().end() && "Global value not in node!");
00378   }
00379 
00380   void AssertCallSiteInGraph(const DSCallSite &CS) const;
00381   void AssertCallNodesInGraph() const;
00382   void AssertAuxCallNodesInGraph() const;
00383 
00384   void AssertGraphOK() const;
00385 
00386   /// removeTriviallyDeadNodes - After the graph has been constructed, this
00387   /// method removes all unreachable nodes that are created because they got
00388   /// merged with other nodes in the graph.  This is used as the first step of
00389   /// removeDeadNodes.
00390   ///
00391   void removeTriviallyDeadNodes();
00392 };
00393 
00394 
00395 /// ReachabilityCloner - This class is used to incrementally clone and merge
00396 /// nodes from a non-changing source graph into a potentially mutating
00397 /// destination graph.  Nodes are only cloned over on demand, either in
00398 /// responds to a merge() or getClonedNH() call.  When a node is cloned over,
00399 /// all of the nodes reachable from it are automatically brought over as well.
00400 ///
00401 class ReachabilityCloner {
00402   DSGraph &Dest;
00403   const DSGraph &Src;
00404 
00405   /// BitsToKeep - These bits are retained from the source node when the
00406   /// source nodes are merged into the destination graph.
00407   unsigned BitsToKeep;
00408   unsigned CloneFlags;
00409 
00410   // NodeMap - A mapping from nodes in the source graph to the nodes that
00411   // represent them in the destination graph.
00412   DSGraph::NodeMapTy NodeMap;
00413 public:
00414   ReachabilityCloner(DSGraph &dest, const DSGraph &src, unsigned cloneFlags)
00415     : Dest(dest), Src(src), CloneFlags(cloneFlags) {
00416     assert(&Dest != &Src && "Cannot clone from graph to same graph!");
00417     BitsToKeep = ~DSNode::DEAD;
00418     if (CloneFlags & DSGraph::StripAllocaBit)
00419       BitsToKeep &= ~DSNode::AllocaNode;
00420     if (CloneFlags & DSGraph::StripModRefBits)
00421       BitsToKeep &= ~(DSNode::Modified | DSNode::Read);
00422     if (CloneFlags & DSGraph::StripIncompleteBit)
00423       BitsToKeep &= ~DSNode::Incomplete;
00424   }
00425   
00426   DSNodeHandle getClonedNH(const DSNodeHandle &SrcNH);
00427 
00428   void merge(const DSNodeHandle &NH, const DSNodeHandle &SrcNH);
00429 
00430   /// mergeCallSite - Merge the nodes reachable from the specified src call
00431   /// site into the nodes reachable from DestCS.
00432   ///
00433   void mergeCallSite(const DSCallSite &DestCS, const DSCallSite &SrcCS);
00434 
00435   bool clonedAnyNodes() const { return !NodeMap.empty(); }
00436 
00437   /// hasClonedNode - Return true if the specified node has been cloned from
00438   /// the source graph into the destination graph.
00439   bool hasClonedNode(const DSNode *N) {
00440     return NodeMap.count(N);
00441   }
00442 
00443   void destroy() { NodeMap.clear(); }
00444 };
00445 
00446 } // End llvm namespace
00447 
00448 #endif