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DataStructure.cpp

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00001 //===- DataStructure.cpp - Implement the core data structure analysis -----===//
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 file implements the core data structure functionality.
00011 //
00012 //===----------------------------------------------------------------------===//
00013 
00014 #include "llvm/Analysis/DataStructure/DSGraphTraits.h"
00015 #include "llvm/Constants.h"
00016 #include "llvm/Function.h"
00017 #include "llvm/GlobalVariable.h"
00018 #include "llvm/Instructions.h"
00019 #include "llvm/DerivedTypes.h"
00020 #include "llvm/Target/TargetData.h"
00021 #include "llvm/Assembly/Writer.h"
00022 #include "llvm/Support/CommandLine.h"
00023 #include "llvm/Support/Debug.h"
00024 #include "llvm/ADT/DepthFirstIterator.h"
00025 #include "llvm/ADT/STLExtras.h"
00026 #include "llvm/ADT/SCCIterator.h"
00027 #include "llvm/ADT/Statistic.h"
00028 #include "llvm/Support/Timer.h"
00029 #include <iostream>
00030 #include <algorithm>
00031 using namespace llvm;
00032 
00033 #define COLLAPSE_ARRAYS_AGGRESSIVELY 0
00034 
00035 namespace {
00036   Statistic<> NumFolds          ("dsa", "Number of nodes completely folded");
00037   Statistic<> NumCallNodesMerged("dsa", "Number of call nodes merged");
00038   Statistic<> NumNodeAllocated  ("dsa", "Number of nodes allocated");
00039   Statistic<> NumDNE            ("dsa", "Number of nodes removed by reachability");
00040   Statistic<> NumTrivialDNE     ("dsa", "Number of nodes trivially removed");
00041   Statistic<> NumTrivialGlobalDNE("dsa", "Number of globals trivially removed");
00042   static cl::opt<unsigned>
00043   DSAFieldLimit("dsa-field-limit", cl::Hidden,
00044                 cl::desc("Number of fields to track before collapsing a node"),
00045                 cl::init(256));
00046 }
00047 
00048 #if 0
00049 #define TIME_REGION(VARNAME, DESC) \
00050    NamedRegionTimer VARNAME(DESC)
00051 #else
00052 #define TIME_REGION(VARNAME, DESC)
00053 #endif
00054 
00055 using namespace DS;
00056 
00057 /// isForwarding - Return true if this NodeHandle is forwarding to another
00058 /// one.
00059 bool DSNodeHandle::isForwarding() const {
00060   return N && N->isForwarding();
00061 }
00062 
00063 DSNode *DSNodeHandle::HandleForwarding() const {
00064   assert(N->isForwarding() && "Can only be invoked if forwarding!");
00065 
00066   // Handle node forwarding here!
00067   DSNode *Next = N->ForwardNH.getNode();  // Cause recursive shrinkage
00068   Offset += N->ForwardNH.getOffset();
00069 
00070   if (--N->NumReferrers == 0) {
00071     // Removing the last referrer to the node, sever the forwarding link
00072     N->stopForwarding();
00073   }
00074 
00075   N = Next;
00076   N->NumReferrers++;
00077   if (N->Size <= Offset) {
00078     assert(N->Size <= 1 && "Forwarded to shrunk but not collapsed node?");
00079     Offset = 0;
00080   }
00081   return N;
00082 }
00083 
00084 //===----------------------------------------------------------------------===//
00085 // DSScalarMap Implementation
00086 //===----------------------------------------------------------------------===//
00087 
00088 DSNodeHandle &DSScalarMap::AddGlobal(GlobalValue *GV) {
00089   assert(ValueMap.count(GV) == 0 && "GV already exists!");
00090 
00091   // If the node doesn't exist, check to see if it's a global that is
00092   // equated to another global in the program.
00093   EquivalenceClasses<GlobalValue*>::iterator ECI = GlobalECs.findValue(GV);
00094   if (ECI != GlobalECs.end()) {
00095     GlobalValue *Leader = *GlobalECs.findLeader(ECI);
00096     if (Leader != GV) {
00097       GV = Leader;
00098       iterator I = ValueMap.find(GV);
00099       if (I != ValueMap.end())
00100         return I->second;
00101     }
00102   }
00103 
00104   // Okay, this is either not an equivalenced global or it is the leader, it
00105   // will be inserted into the scalar map now.
00106   GlobalSet.insert(GV);
00107 
00108   return ValueMap.insert(std::make_pair(GV, DSNodeHandle())).first->second;
00109 }
00110 
00111 
00112 //===----------------------------------------------------------------------===//
00113 // DSNode Implementation
00114 //===----------------------------------------------------------------------===//
00115 
00116 DSNode::DSNode(const Type *T, DSGraph *G)
00117   : NumReferrers(0), Size(0), ParentGraph(G), Ty(Type::VoidTy), NodeType(0) {
00118   // Add the type entry if it is specified...
00119   if (T) mergeTypeInfo(T, 0);
00120   if (G) G->addNode(this);
00121   ++NumNodeAllocated;
00122 }
00123 
00124 // DSNode copy constructor... do not copy over the referrers list!
00125 DSNode::DSNode(const DSNode &N, DSGraph *G, bool NullLinks)
00126   : NumReferrers(0), Size(N.Size), ParentGraph(G),
00127     Ty(N.Ty), Globals(N.Globals), NodeType(N.NodeType) {
00128   if (!NullLinks) {
00129     Links = N.Links;
00130   } else
00131     Links.resize(N.Links.size()); // Create the appropriate number of null links
00132   G->addNode(this);
00133   ++NumNodeAllocated;
00134 }
00135 
00136 /// getTargetData - Get the target data object used to construct this node.
00137 ///
00138 const TargetData &DSNode::getTargetData() const {
00139   return ParentGraph->getTargetData();
00140 }
00141 
00142 void DSNode::assertOK() const {
00143   assert((Ty != Type::VoidTy ||
00144           Ty == Type::VoidTy && (Size == 0 ||
00145                                  (NodeType & DSNode::Array))) &&
00146          "Node not OK!");
00147 
00148   assert(ParentGraph && "Node has no parent?");
00149   const DSScalarMap &SM = ParentGraph->getScalarMap();
00150   for (unsigned i = 0, e = Globals.size(); i != e; ++i) {
00151     assert(SM.global_count(Globals[i]));
00152     assert(SM.find(Globals[i])->second.getNode() == this);
00153   }
00154 }
00155 
00156 /// forwardNode - Mark this node as being obsolete, and all references to it
00157 /// should be forwarded to the specified node and offset.
00158 ///
00159 void DSNode::forwardNode(DSNode *To, unsigned Offset) {
00160   assert(this != To && "Cannot forward a node to itself!");
00161   assert(ForwardNH.isNull() && "Already forwarding from this node!");
00162   if (To->Size <= 1) Offset = 0;
00163   assert((Offset < To->Size || (Offset == To->Size && Offset == 0)) &&
00164          "Forwarded offset is wrong!");
00165   ForwardNH.setTo(To, Offset);
00166   NodeType = DEAD;
00167   Size = 0;
00168   Ty = Type::VoidTy;
00169 
00170   // Remove this node from the parent graph's Nodes list.
00171   ParentGraph->unlinkNode(this);
00172   ParentGraph = 0;
00173 }
00174 
00175 // addGlobal - Add an entry for a global value to the Globals list.  This also
00176 // marks the node with the 'G' flag if it does not already have it.
00177 //
00178 void DSNode::addGlobal(GlobalValue *GV) {
00179   // First, check to make sure this is the leader if the global is in an
00180   // equivalence class.
00181   GV = getParentGraph()->getScalarMap().getLeaderForGlobal(GV);
00182 
00183   // Keep the list sorted.
00184   std::vector<GlobalValue*>::iterator I =
00185     std::lower_bound(Globals.begin(), Globals.end(), GV);
00186 
00187   if (I == Globals.end() || *I != GV) {
00188     Globals.insert(I, GV);
00189     NodeType |= GlobalNode;
00190   }
00191 }
00192 
00193 // removeGlobal - Remove the specified global that is explicitly in the globals
00194 // list.
00195 void DSNode::removeGlobal(GlobalValue *GV) {
00196   std::vector<GlobalValue*>::iterator I =
00197     std::lower_bound(Globals.begin(), Globals.end(), GV);
00198   assert(I != Globals.end() && *I == GV && "Global not in node!");
00199   Globals.erase(I);
00200 }
00201 
00202 /// foldNodeCompletely - If we determine that this node has some funny
00203 /// behavior happening to it that we cannot represent, we fold it down to a
00204 /// single, completely pessimistic, node.  This node is represented as a
00205 /// single byte with a single TypeEntry of "void".
00206 ///
00207 void DSNode::foldNodeCompletely() {
00208   if (isNodeCompletelyFolded()) return;  // If this node is already folded...
00209 
00210   ++NumFolds;
00211 
00212   // If this node has a size that is <= 1, we don't need to create a forwarding
00213   // node.
00214   if (getSize() <= 1) {
00215     NodeType |= DSNode::Array;
00216     Ty = Type::VoidTy;
00217     Size = 1;
00218     assert(Links.size() <= 1 && "Size is 1, but has more links?");
00219     Links.resize(1);
00220   } else {
00221     // Create the node we are going to forward to.  This is required because
00222     // some referrers may have an offset that is > 0.  By forcing them to
00223     // forward, the forwarder has the opportunity to correct the offset.
00224     DSNode *DestNode = new DSNode(0, ParentGraph);
00225     DestNode->NodeType = NodeType|DSNode::Array;
00226     DestNode->Ty = Type::VoidTy;
00227     DestNode->Size = 1;
00228     DestNode->Globals.swap(Globals);
00229 
00230     // Start forwarding to the destination node...
00231     forwardNode(DestNode, 0);
00232 
00233     if (!Links.empty()) {
00234       DestNode->Links.reserve(1);
00235 
00236       DSNodeHandle NH(DestNode);
00237       DestNode->Links.push_back(Links[0]);
00238 
00239       // If we have links, merge all of our outgoing links together...
00240       for (unsigned i = Links.size()-1; i != 0; --i)
00241         NH.getNode()->Links[0].mergeWith(Links[i]);
00242       Links.clear();
00243     } else {
00244       DestNode->Links.resize(1);
00245     }
00246   }
00247 }
00248 
00249 /// isNodeCompletelyFolded - Return true if this node has been completely
00250 /// folded down to something that can never be expanded, effectively losing
00251 /// all of the field sensitivity that may be present in the node.
00252 ///
00253 bool DSNode::isNodeCompletelyFolded() const {
00254   return getSize() == 1 && Ty == Type::VoidTy && isArray();
00255 }
00256 
00257 /// addFullGlobalsList - Compute the full set of global values that are
00258 /// represented by this node.  Unlike getGlobalsList(), this requires fair
00259 /// amount of work to compute, so don't treat this method call as free.
00260 void DSNode::addFullGlobalsList(std::vector<GlobalValue*> &List) const {
00261   if (globals_begin() == globals_end()) return;
00262 
00263   EquivalenceClasses<GlobalValue*> &EC = getParentGraph()->getGlobalECs();
00264 
00265   for (globals_iterator I = globals_begin(), E = globals_end(); I != E; ++I) {
00266     EquivalenceClasses<GlobalValue*>::iterator ECI = EC.findValue(*I);
00267     if (ECI == EC.end())
00268       List.push_back(*I);
00269     else
00270       List.insert(List.end(), EC.member_begin(ECI), EC.member_end());
00271   }
00272 }
00273 
00274 /// addFullFunctionList - Identical to addFullGlobalsList, but only return the
00275 /// functions in the full list.
00276 void DSNode::addFullFunctionList(std::vector<Function*> &List) const {
00277   if (globals_begin() == globals_end()) return;
00278 
00279   EquivalenceClasses<GlobalValue*> &EC = getParentGraph()->getGlobalECs();
00280 
00281   for (globals_iterator I = globals_begin(), E = globals_end(); I != E; ++I) {
00282     EquivalenceClasses<GlobalValue*>::iterator ECI = EC.findValue(*I);
00283     if (ECI == EC.end()) {
00284       if (Function *F = dyn_cast<Function>(*I))
00285         List.push_back(F);
00286     } else {
00287       for (EquivalenceClasses<GlobalValue*>::member_iterator MI =
00288              EC.member_begin(ECI), E = EC.member_end(); MI != E; ++MI)
00289         if (Function *F = dyn_cast<Function>(*MI))
00290           List.push_back(F);
00291     }
00292   }
00293 }
00294 
00295 namespace {
00296   /// TypeElementWalker Class - Used for implementation of physical subtyping...
00297   ///
00298   class TypeElementWalker {
00299     struct StackState {
00300       const Type *Ty;
00301       unsigned Offset;
00302       unsigned Idx;
00303       StackState(const Type *T, unsigned Off = 0)
00304         : Ty(T), Offset(Off), Idx(0) {}
00305     };
00306 
00307     std::vector<StackState> Stack;
00308     const TargetData &TD;
00309   public:
00310     TypeElementWalker(const Type *T, const TargetData &td) : TD(td) {
00311       Stack.push_back(T);
00312       StepToLeaf();
00313     }
00314 
00315     bool isDone() const { return Stack.empty(); }
00316     const Type *getCurrentType()   const { return Stack.back().Ty;     }
00317     unsigned    getCurrentOffset() const { return Stack.back().Offset; }
00318 
00319     void StepToNextType() {
00320       PopStackAndAdvance();
00321       StepToLeaf();
00322     }
00323 
00324   private:
00325     /// PopStackAndAdvance - Pop the current element off of the stack and
00326     /// advance the underlying element to the next contained member.
00327     void PopStackAndAdvance() {
00328       assert(!Stack.empty() && "Cannot pop an empty stack!");
00329       Stack.pop_back();
00330       while (!Stack.empty()) {
00331         StackState &SS = Stack.back();
00332         if (const StructType *ST = dyn_cast<StructType>(SS.Ty)) {
00333           ++SS.Idx;
00334           if (SS.Idx != ST->getNumElements()) {
00335             const StructLayout *SL = TD.getStructLayout(ST);
00336             SS.Offset +=
00337                unsigned(SL->MemberOffsets[SS.Idx]-SL->MemberOffsets[SS.Idx-1]);
00338             return;
00339           }
00340           Stack.pop_back();  // At the end of the structure
00341         } else {
00342           const ArrayType *AT = cast<ArrayType>(SS.Ty);
00343           ++SS.Idx;
00344           if (SS.Idx != AT->getNumElements()) {
00345             SS.Offset += unsigned(TD.getTypeSize(AT->getElementType()));
00346             return;
00347           }
00348           Stack.pop_back();  // At the end of the array
00349         }
00350       }
00351     }
00352 
00353     /// StepToLeaf - Used by physical subtyping to move to the first leaf node
00354     /// on the type stack.
00355     void StepToLeaf() {
00356       if (Stack.empty()) return;
00357       while (!Stack.empty() && !Stack.back().Ty->isFirstClassType()) {
00358         StackState &SS = Stack.back();
00359         if (const StructType *ST = dyn_cast<StructType>(SS.Ty)) {
00360           if (ST->getNumElements() == 0) {
00361             assert(SS.Idx == 0);
00362             PopStackAndAdvance();
00363           } else {
00364             // Step into the structure...
00365             assert(SS.Idx < ST->getNumElements());
00366             const StructLayout *SL = TD.getStructLayout(ST);
00367             Stack.push_back(StackState(ST->getElementType(SS.Idx),
00368                             SS.Offset+unsigned(SL->MemberOffsets[SS.Idx])));
00369           }
00370         } else {
00371           const ArrayType *AT = cast<ArrayType>(SS.Ty);
00372           if (AT->getNumElements() == 0) {
00373             assert(SS.Idx == 0);
00374             PopStackAndAdvance();
00375           } else {
00376             // Step into the array...
00377             assert(SS.Idx < AT->getNumElements());
00378             Stack.push_back(StackState(AT->getElementType(),
00379                                        SS.Offset+SS.Idx*
00380                              unsigned(TD.getTypeSize(AT->getElementType()))));
00381           }
00382         }
00383       }
00384     }
00385   };
00386 } // end anonymous namespace
00387 
00388 /// ElementTypesAreCompatible - Check to see if the specified types are
00389 /// "physically" compatible.  If so, return true, else return false.  We only
00390 /// have to check the fields in T1: T2 may be larger than T1.  If AllowLargerT1
00391 /// is true, then we also allow a larger T1.
00392 ///
00393 static bool ElementTypesAreCompatible(const Type *T1, const Type *T2,
00394                                       bool AllowLargerT1, const TargetData &TD){
00395   TypeElementWalker T1W(T1, TD), T2W(T2, TD);
00396 
00397   while (!T1W.isDone() && !T2W.isDone()) {
00398     if (T1W.getCurrentOffset() != T2W.getCurrentOffset())
00399       return false;
00400 
00401     const Type *T1 = T1W.getCurrentType();
00402     const Type *T2 = T2W.getCurrentType();
00403     if (T1 != T2 && !T1->isLosslesslyConvertibleTo(T2))
00404       return false;
00405 
00406     T1W.StepToNextType();
00407     T2W.StepToNextType();
00408   }
00409 
00410   return AllowLargerT1 || T1W.isDone();
00411 }
00412 
00413 
00414 /// mergeTypeInfo - This method merges the specified type into the current node
00415 /// at the specified offset.  This may update the current node's type record if
00416 /// this gives more information to the node, it may do nothing to the node if
00417 /// this information is already known, or it may merge the node completely (and
00418 /// return true) if the information is incompatible with what is already known.
00419 ///
00420 /// This method returns true if the node is completely folded, otherwise false.
00421 ///
00422 bool DSNode::mergeTypeInfo(const Type *NewTy, unsigned Offset,
00423                            bool FoldIfIncompatible) {
00424   const TargetData &TD = getTargetData();
00425   // Check to make sure the Size member is up-to-date.  Size can be one of the
00426   // following:
00427   //  Size = 0, Ty = Void: Nothing is known about this node.
00428   //  Size = 0, Ty = FnTy: FunctionPtr doesn't have a size, so we use zero
00429   //  Size = 1, Ty = Void, Array = 1: The node is collapsed
00430   //  Otherwise, sizeof(Ty) = Size
00431   //
00432   assert(((Size == 0 && Ty == Type::VoidTy && !isArray()) ||
00433           (Size == 0 && !Ty->isSized() && !isArray()) ||
00434           (Size == 1 && Ty == Type::VoidTy && isArray()) ||
00435           (Size == 0 && !Ty->isSized() && !isArray()) ||
00436           (TD.getTypeSize(Ty) == Size)) &&
00437          "Size member of DSNode doesn't match the type structure!");
00438   assert(NewTy != Type::VoidTy && "Cannot merge void type into DSNode!");
00439 
00440   if (Offset == 0 && NewTy == Ty)
00441     return false;  // This should be a common case, handle it efficiently
00442 
00443   // Return true immediately if the node is completely folded.
00444   if (isNodeCompletelyFolded()) return true;
00445 
00446   // If this is an array type, eliminate the outside arrays because they won't
00447   // be used anyway.  This greatly reduces the size of large static arrays used
00448   // as global variables, for example.
00449   //
00450   bool WillBeArray = false;
00451   while (const ArrayType *AT = dyn_cast<ArrayType>(NewTy)) {
00452     // FIXME: we might want to keep small arrays, but must be careful about
00453     // things like: [2 x [10000 x int*]]
00454     NewTy = AT->getElementType();
00455     WillBeArray = true;
00456   }
00457 
00458   // Figure out how big the new type we're merging in is...
00459   unsigned NewTySize = NewTy->isSized() ? (unsigned)TD.getTypeSize(NewTy) : 0;
00460 
00461   // Otherwise check to see if we can fold this type into the current node.  If
00462   // we can't, we fold the node completely, if we can, we potentially update our
00463   // internal state.
00464   //
00465   if (Ty == Type::VoidTy) {
00466     // If this is the first type that this node has seen, just accept it without
00467     // question....
00468     assert(Offset == 0 && !isArray() &&
00469            "Cannot have an offset into a void node!");
00470 
00471     // If this node would have to have an unreasonable number of fields, just
00472     // collapse it.  This can occur for fortran common blocks, which have stupid
00473     // things like { [100000000 x double], [1000000 x double] }.
00474     unsigned NumFields = (NewTySize+DS::PointerSize-1) >> DS::PointerShift;
00475     if (NumFields > DSAFieldLimit) {
00476       foldNodeCompletely();
00477       return true;
00478     }
00479 
00480     Ty = NewTy;
00481     NodeType &= ~Array;
00482     if (WillBeArray) NodeType |= Array;
00483     Size = NewTySize;
00484 
00485     // Calculate the number of outgoing links from this node.
00486     Links.resize(NumFields);
00487     return false;
00488   }
00489 
00490   // Handle node expansion case here...
00491   if (Offset+NewTySize > Size) {
00492     // It is illegal to grow this node if we have treated it as an array of
00493     // objects...
00494     if (isArray()) {
00495       if (FoldIfIncompatible) foldNodeCompletely();
00496       return true;
00497     }
00498 
00499     // If this node would have to have an unreasonable number of fields, just
00500     // collapse it.  This can occur for fortran common blocks, which have stupid
00501     // things like { [100000000 x double], [1000000 x double] }.
00502     unsigned NumFields = (NewTySize+Offset+DS::PointerSize-1) >> DS::PointerShift;
00503     if (NumFields > DSAFieldLimit) {
00504       foldNodeCompletely();
00505       return true;
00506     }
00507 
00508     if (Offset) {
00509       //handle some common cases:
00510       // Ty:    struct { t1, t2, t3, t4, ..., tn}
00511       // NewTy: struct { offset, stuff...}
00512       // try merge with NewTy: struct {t1, t2, stuff...} if offset lands exactly on a field in Ty
00513       if (isa<StructType>(NewTy) && isa<StructType>(Ty)) {
00514         DEBUG(std::cerr << "Ty: " << *Ty << "\nNewTy: " << *NewTy << "@" << Offset << "\n");
00515         unsigned O = 0;
00516         const StructType *STy = cast<StructType>(Ty);
00517         const StructLayout &SL = *TD.getStructLayout(STy);
00518         unsigned i = SL.getElementContainingOffset(Offset);
00519         //Either we hit it exactly or give up
00520         if (SL.MemberOffsets[i] != Offset) {
00521           if (FoldIfIncompatible) foldNodeCompletely();
00522           return true;
00523         }
00524         std::vector<const Type*> nt;
00525         for (unsigned x = 0; x < i; ++x)
00526           nt.push_back(STy->getElementType(x));
00527         STy = cast<StructType>(NewTy);
00528         nt.insert(nt.end(), STy->element_begin(), STy->element_end());
00529         //and merge
00530         STy = StructType::get(nt);
00531         DEBUG(std::cerr << "Trying with: " << *STy << "\n");
00532         return mergeTypeInfo(STy, 0);
00533       }
00534 
00535       //Ty: struct { t1, t2, t3 ... tn}
00536       //NewTy T offset x
00537       //try merge with NewTy: struct : {t1, t2, T} if offset lands on a field in Ty
00538       if (isa<StructType>(Ty)) {
00539         DEBUG(std::cerr << "Ty: " << *Ty << "\nNewTy: " << *NewTy << "@" << Offset << "\n");
00540         unsigned O = 0;
00541         const StructType *STy = cast<StructType>(Ty);
00542         const StructLayout &SL = *TD.getStructLayout(STy);
00543         unsigned i = SL.getElementContainingOffset(Offset);
00544         //Either we hit it exactly or give up
00545         if (SL.MemberOffsets[i] != Offset) {
00546           if (FoldIfIncompatible) foldNodeCompletely();
00547           return true;
00548         }
00549         std::vector<const Type*> nt;
00550         for (unsigned x = 0; x < i; ++x)
00551           nt.push_back(STy->getElementType(x));
00552         nt.push_back(NewTy);
00553         //and merge
00554         STy = StructType::get(nt);
00555         DEBUG(std::cerr << "Trying with: " << *STy << "\n");
00556         return mergeTypeInfo(STy, 0);
00557       }
00558 
00559       std::cerr << "UNIMP: Trying to merge a growth type into "
00560                 << "offset != 0: Collapsing!\n";
00561       abort();
00562       if (FoldIfIncompatible) foldNodeCompletely();
00563       return true;
00564 
00565     }
00566 
00567 
00568     // Okay, the situation is nice and simple, we are trying to merge a type in
00569     // at offset 0 that is bigger than our current type.  Implement this by
00570     // switching to the new type and then merge in the smaller one, which should
00571     // hit the other code path here.  If the other code path decides it's not
00572     // ok, it will collapse the node as appropriate.
00573     //
00574 
00575     const Type *OldTy = Ty;
00576     Ty = NewTy;
00577     NodeType &= ~Array;
00578     if (WillBeArray) NodeType |= Array;
00579     Size = NewTySize;
00580 
00581     // Must grow links to be the appropriate size...
00582     Links.resize(NumFields);
00583 
00584     // Merge in the old type now... which is guaranteed to be smaller than the
00585     // "current" type.
00586     return mergeTypeInfo(OldTy, 0);
00587   }
00588 
00589   assert(Offset <= Size &&
00590          "Cannot merge something into a part of our type that doesn't exist!");
00591 
00592   // Find the section of Ty that NewTy overlaps with... first we find the
00593   // type that starts at offset Offset.
00594   //
00595   unsigned O = 0;
00596   const Type *SubType = Ty;
00597   while (O < Offset) {
00598     assert(Offset-O < TD.getTypeSize(SubType) && "Offset out of range!");
00599 
00600     switch (SubType->getTypeID()) {
00601     case Type::StructTyID: {
00602       const StructType *STy = cast<StructType>(SubType);
00603       const StructLayout &SL = *TD.getStructLayout(STy);
00604       unsigned i = SL.getElementContainingOffset(Offset-O);
00605 
00606       // The offset we are looking for must be in the i'th element...
00607       SubType = STy->getElementType(i);
00608       O += (unsigned)SL.MemberOffsets[i];
00609       break;
00610     }
00611     case Type::ArrayTyID: {
00612       SubType = cast<ArrayType>(SubType)->getElementType();
00613       unsigned ElSize = (unsigned)TD.getTypeSize(SubType);
00614       unsigned Remainder = (Offset-O) % ElSize;
00615       O = Offset-Remainder;
00616       break;
00617     }
00618     default:
00619       if (FoldIfIncompatible) foldNodeCompletely();
00620       return true;
00621     }
00622   }
00623 
00624   assert(O == Offset && "Could not achieve the correct offset!");
00625 
00626   // If we found our type exactly, early exit
00627   if (SubType == NewTy) return false;
00628 
00629   // Differing function types don't require us to merge.  They are not values
00630   // anyway.
00631   if (isa<FunctionType>(SubType) &&
00632       isa<FunctionType>(NewTy)) return false;
00633 
00634   unsigned SubTypeSize = SubType->isSized() ?
00635        (unsigned)TD.getTypeSize(SubType) : 0;
00636 
00637   // Ok, we are getting desperate now.  Check for physical subtyping, where we
00638   // just require each element in the node to be compatible.
00639   if (NewTySize <= SubTypeSize && NewTySize && NewTySize < 256 &&
00640       SubTypeSize && SubTypeSize < 256 &&
00641       ElementTypesAreCompatible(NewTy, SubType, !isArray(), TD))
00642     return false;
00643 
00644   // Okay, so we found the leader type at the offset requested.  Search the list
00645   // of types that starts at this offset.  If SubType is currently an array or
00646   // structure, the type desired may actually be the first element of the
00647   // composite type...
00648   //
00649   unsigned PadSize = SubTypeSize; // Size, including pad memory which is ignored
00650   while (SubType != NewTy) {
00651     const Type *NextSubType = 0;
00652     unsigned NextSubTypeSize = 0;
00653     unsigned NextPadSize = 0;
00654     switch (SubType->getTypeID()) {
00655     case Type::StructTyID: {
00656       const StructType *STy = cast<StructType>(SubType);
00657       const StructLayout &SL = *TD.getStructLayout(STy);
00658       if (SL.MemberOffsets.size() > 1)
00659         NextPadSize = (unsigned)SL.MemberOffsets[1];
00660       else
00661         NextPadSize = SubTypeSize;
00662       NextSubType = STy->getElementType(0);
00663       NextSubTypeSize = (unsigned)TD.getTypeSize(NextSubType);
00664       break;
00665     }
00666     case Type::ArrayTyID:
00667       NextSubType = cast<ArrayType>(SubType)->getElementType();
00668       NextSubTypeSize = (unsigned)TD.getTypeSize(NextSubType);
00669       NextPadSize = NextSubTypeSize;
00670       break;
00671     default: ;
00672       // fall out
00673     }
00674 
00675     if (NextSubType == 0)
00676       break;   // In the default case, break out of the loop
00677 
00678     if (NextPadSize < NewTySize)
00679       break;   // Don't allow shrinking to a smaller type than NewTySize
00680     SubType = NextSubType;
00681     SubTypeSize = NextSubTypeSize;
00682     PadSize = NextPadSize;
00683   }
00684 
00685   // If we found the type exactly, return it...
00686   if (SubType == NewTy)
00687     return false;
00688 
00689   // Check to see if we have a compatible, but different type...
00690   if (NewTySize == SubTypeSize) {
00691     // Check to see if this type is obviously convertible... int -> uint f.e.
00692     if (NewTy->isLosslesslyConvertibleTo(SubType))
00693       return false;
00694 
00695     // Check to see if we have a pointer & integer mismatch going on here,
00696     // loading a pointer as a long, for example.
00697     //
00698     if (SubType->isInteger() && isa<PointerType>(NewTy) ||
00699         NewTy->isInteger() && isa<PointerType>(SubType))
00700       return false;
00701   } else if (NewTySize > SubTypeSize && NewTySize <= PadSize) {
00702     // We are accessing the field, plus some structure padding.  Ignore the
00703     // structure padding.
00704     return false;
00705   }
00706 
00707   Module *M = 0;
00708   if (getParentGraph()->retnodes_begin() != getParentGraph()->retnodes_end())
00709     M = getParentGraph()->retnodes_begin()->first->getParent();
00710   DEBUG(std::cerr << "MergeTypeInfo Folding OrigTy: ";
00711         WriteTypeSymbolic(std::cerr, Ty, M) << "\n due to:";
00712         WriteTypeSymbolic(std::cerr, NewTy, M) << " @ " << Offset << "!\n"
00713                   << "SubType: ";
00714         WriteTypeSymbolic(std::cerr, SubType, M) << "\n\n");
00715 
00716   if (FoldIfIncompatible) foldNodeCompletely();
00717   return true;
00718 }
00719 
00720 
00721 
00722 /// addEdgeTo - Add an edge from the current node to the specified node.  This
00723 /// can cause merging of nodes in the graph.
00724 ///
00725 void DSNode::addEdgeTo(unsigned Offset, const DSNodeHandle &NH) {
00726   if (NH.isNull()) return;       // Nothing to do
00727 
00728   if (isNodeCompletelyFolded())
00729     Offset = 0;
00730 
00731   DSNodeHandle &ExistingEdge = getLink(Offset);
00732   if (!ExistingEdge.isNull()) {
00733     // Merge the two nodes...
00734     ExistingEdge.mergeWith(NH);
00735   } else {                             // No merging to perform...
00736     setLink(Offset, NH);               // Just force a link in there...
00737   }
00738 }
00739 
00740 
00741 /// MergeSortedVectors - Efficiently merge a vector into another vector where
00742 /// duplicates are not allowed and both are sorted.  This assumes that 'T's are
00743 /// efficiently copyable and have sane comparison semantics.
00744 ///
00745 static void MergeSortedVectors(std::vector<GlobalValue*> &Dest,
00746                                const std::vector<GlobalValue*> &Src) {
00747   // By far, the most common cases will be the simple ones.  In these cases,
00748   // avoid having to allocate a temporary vector...
00749   //
00750   if (Src.empty()) {             // Nothing to merge in...
00751     return;
00752   } else if (Dest.empty()) {     // Just copy the result in...
00753     Dest = Src;
00754   } else if (Src.size() == 1) {  // Insert a single element...
00755     const GlobalValue *V = Src[0];
00756     std::vector<GlobalValue*>::iterator I =
00757       std::lower_bound(Dest.begin(), Dest.end(), V);
00758     if (I == Dest.end() || *I != Src[0])  // If not already contained...
00759       Dest.insert(I, Src[0]);
00760   } else if (Dest.size() == 1) {
00761     GlobalValue *Tmp = Dest[0];           // Save value in temporary...
00762     Dest = Src;                           // Copy over list...
00763     std::vector<GlobalValue*>::iterator I =
00764       std::lower_bound(Dest.begin(), Dest.end(), Tmp);
00765     if (I == Dest.end() || *I != Tmp)     // If not already contained...
00766       Dest.insert(I, Tmp);
00767 
00768   } else {
00769     // Make a copy to the side of Dest...
00770     std::vector<GlobalValue*> Old(Dest);
00771 
00772     // Make space for all of the type entries now...
00773     Dest.resize(Dest.size()+Src.size());
00774 
00775     // Merge the two sorted ranges together... into Dest.
00776     std::merge(Old.begin(), Old.end(), Src.begin(), Src.end(), Dest.begin());
00777 
00778     // Now erase any duplicate entries that may have accumulated into the
00779     // vectors (because they were in both of the input sets)
00780     Dest.erase(std::unique(Dest.begin(), Dest.end()), Dest.end());
00781   }
00782 }
00783 
00784 void DSNode::mergeGlobals(const std::vector<GlobalValue*> &RHS) {
00785   MergeSortedVectors(Globals, RHS);
00786 }
00787 
00788 // MergeNodes - Helper function for DSNode::mergeWith().
00789 // This function does the hard work of merging two nodes, CurNodeH
00790 // and NH after filtering out trivial cases and making sure that
00791 // CurNodeH.offset >= NH.offset.
00792 //
00793 // ***WARNING***
00794 // Since merging may cause either node to go away, we must always
00795 // use the node-handles to refer to the nodes.  These node handles are
00796 // automatically updated during merging, so will always provide access
00797 // to the correct node after a merge.
00798 //
00799 void DSNode::MergeNodes(DSNodeHandle& CurNodeH, DSNodeHandle& NH) {
00800   assert(CurNodeH.getOffset() >= NH.getOffset() &&
00801          "This should have been enforced in the caller.");
00802   assert(CurNodeH.getNode()->getParentGraph()==NH.getNode()->getParentGraph() &&
00803          "Cannot merge two nodes that are not in the same graph!");
00804 
00805   // Now we know that Offset >= NH.Offset, so convert it so our "Offset" (with
00806   // respect to NH.Offset) is now zero.  NOffset is the distance from the base
00807   // of our object that N starts from.
00808   //
00809   unsigned NOffset = CurNodeH.getOffset()-NH.getOffset();
00810   unsigned NSize = NH.getNode()->getSize();
00811 
00812   // If the two nodes are of different size, and the smaller node has the array
00813   // bit set, collapse!
00814   if (NSize != CurNodeH.getNode()->getSize()) {
00815 #if COLLAPSE_ARRAYS_AGGRESSIVELY
00816     if (NSize < CurNodeH.getNode()->getSize()) {
00817       if (NH.getNode()->isArray())
00818         NH.getNode()->foldNodeCompletely();
00819     } else if (CurNodeH.getNode()->isArray()) {
00820       NH.getNode()->foldNodeCompletely();
00821     }
00822 #endif
00823   }
00824 
00825   // Merge the type entries of the two nodes together...
00826   if (NH.getNode()->Ty != Type::VoidTy)
00827     CurNodeH.getNode()->mergeTypeInfo(NH.getNode()->Ty, NOffset);
00828   assert(!CurNodeH.getNode()->isDeadNode());
00829 
00830   // If we are merging a node with a completely folded node, then both nodes are
00831   // now completely folded.
00832   //
00833   if (CurNodeH.getNode()->isNodeCompletelyFolded()) {
00834     if (!NH.getNode()->isNodeCompletelyFolded()) {
00835       NH.getNode()->foldNodeCompletely();
00836       assert(NH.getNode() && NH.getOffset() == 0 &&
00837              "folding did not make offset 0?");
00838       NOffset = NH.getOffset();
00839       NSize = NH.getNode()->getSize();
00840       assert(NOffset == 0 && NSize == 1);
00841     }
00842   } else if (NH.getNode()->isNodeCompletelyFolded()) {
00843     CurNodeH.getNode()->foldNodeCompletely();
00844     assert(CurNodeH.getNode() && CurNodeH.getOffset() == 0 &&
00845            "folding did not make offset 0?");
00846     NSize = NH.getNode()->getSize();
00847     NOffset = NH.getOffset();
00848     assert(NOffset == 0 && NSize == 1);
00849   }
00850 
00851   DSNode *N = NH.getNode();
00852   if (CurNodeH.getNode() == N || N == 0) return;
00853   assert(!CurNodeH.getNode()->isDeadNode());
00854 
00855   // Merge the NodeType information.
00856   CurNodeH.getNode()->NodeType |= N->NodeType;
00857 
00858   // Start forwarding to the new node!
00859   N->forwardNode(CurNodeH.getNode(), NOffset);
00860   assert(!CurNodeH.getNode()->isDeadNode());
00861 
00862   // Make all of the outgoing links of N now be outgoing links of CurNodeH.
00863   //
00864   for (unsigned i = 0; i < N->getNumLinks(); ++i) {
00865     DSNodeHandle &Link = N->getLink(i << DS::PointerShift);
00866     if (Link.getNode()) {
00867       // Compute the offset into the current node at which to
00868       // merge this link.  In the common case, this is a linear
00869       // relation to the offset in the original node (with
00870       // wrapping), but if the current node gets collapsed due to
00871       // recursive merging, we must make sure to merge in all remaining
00872       // links at offset zero.
00873       unsigned MergeOffset = 0;
00874       DSNode *CN = CurNodeH.getNode();
00875       if (CN->Size != 1)
00876         MergeOffset = ((i << DS::PointerShift)+NOffset) % CN->getSize();
00877       CN->addEdgeTo(MergeOffset, Link);
00878     }
00879   }
00880 
00881   // Now that there are no outgoing edges, all of the Links are dead.
00882   N->Links.clear();
00883 
00884   // Merge the globals list...
00885   if (!N->Globals.empty()) {
00886     CurNodeH.getNode()->mergeGlobals(N->Globals);
00887 
00888     // Delete the globals from the old node...
00889     std::vector<GlobalValue*>().swap(N->Globals);
00890   }
00891 }
00892 
00893 
00894 /// mergeWith - Merge this node and the specified node, moving all links to and
00895 /// from the argument node into the current node, deleting the node argument.
00896 /// Offset indicates what offset the specified node is to be merged into the
00897 /// current node.
00898 ///
00899 /// The specified node may be a null pointer (in which case, we update it to
00900 /// point to this node).
00901 ///
00902 void DSNode::mergeWith(const DSNodeHandle &NH, unsigned Offset) {
00903   DSNode *N = NH.getNode();
00904   if (N == this && NH.getOffset() == Offset)
00905     return;  // Noop
00906 
00907   // If the RHS is a null node, make it point to this node!
00908   if (N == 0) {
00909     NH.mergeWith(DSNodeHandle(this, Offset));
00910     return;
00911   }
00912 
00913   assert(!N->isDeadNode() && !isDeadNode());
00914   assert(!hasNoReferrers() && "Should not try to fold a useless node!");
00915 
00916   if (N == this) {
00917     // We cannot merge two pieces of the same node together, collapse the node
00918     // completely.
00919     DEBUG(std::cerr << "Attempting to merge two chunks of"
00920                     << " the same node together!\n");
00921     foldNodeCompletely();
00922     return;
00923   }
00924 
00925   // If both nodes are not at offset 0, make sure that we are merging the node
00926   // at an later offset into the node with the zero offset.
00927   //
00928   if (Offset < NH.getOffset()) {
00929     N->mergeWith(DSNodeHandle(this, Offset), NH.getOffset());
00930     return;
00931   } else if (Offset == NH.getOffset() && getSize() < N->getSize()) {
00932     // If the offsets are the same, merge the smaller node into the bigger node
00933     N->mergeWith(DSNodeHandle(this, Offset), NH.getOffset());
00934     return;
00935   }
00936 
00937   // Ok, now we can merge the two nodes.  Use a static helper that works with
00938   // two node handles, since "this" may get merged away at intermediate steps.
00939   DSNodeHandle CurNodeH(this, Offset);
00940   DSNodeHandle NHCopy(NH);
00941   if (CurNodeH.getOffset() >= NHCopy.getOffset())
00942     DSNode::MergeNodes(CurNodeH, NHCopy);
00943   else
00944     DSNode::MergeNodes(NHCopy, CurNodeH);
00945 }
00946 
00947 
00948 //===----------------------------------------------------------------------===//
00949 // ReachabilityCloner Implementation
00950 //===----------------------------------------------------------------------===//
00951 
00952 DSNodeHandle ReachabilityCloner::getClonedNH(const DSNodeHandle &SrcNH) {
00953   if (SrcNH.isNull()) return DSNodeHandle();
00954   const DSNode *SN = SrcNH.getNode();
00955 
00956   DSNodeHandle &NH = NodeMap[SN];
00957   if (!NH.isNull()) {   // Node already mapped?
00958     DSNode *NHN = NH.getNode();
00959     return DSNodeHandle(NHN, NH.getOffset()+SrcNH.getOffset());
00960   }
00961 
00962   // If SrcNH has globals and the destination graph has one of the same globals,
00963   // merge this node with the destination node, which is much more efficient.
00964   if (SN->globals_begin() != SN->globals_end()) {
00965     DSScalarMap &DestSM = Dest.getScalarMap();
00966     for (DSNode::globals_iterator I = SN->globals_begin(),E = SN->globals_end();
00967          I != E; ++I) {
00968       GlobalValue *GV = *I;
00969       DSScalarMap::iterator GI = DestSM.find(GV);
00970       if (GI != DestSM.end() && !GI->second.isNull()) {
00971         // We found one, use merge instead!
00972         merge(GI->second, Src.getNodeForValue(GV));
00973         assert(!NH.isNull() && "Didn't merge node!");
00974         DSNode *NHN = NH.getNode();
00975         return DSNodeHandle(NHN, NH.getOffset()+SrcNH.getOffset());
00976       }
00977     }
00978   }
00979 
00980   DSNode *DN = new DSNode(*SN, &Dest, true /* Null out all links */);
00981   DN->maskNodeTypes(BitsToKeep);
00982   NH = DN;
00983 
00984   // Next, recursively clone all outgoing links as necessary.  Note that
00985   // adding these links can cause the node to collapse itself at any time, and
00986   // the current node may be merged with arbitrary other nodes.  For this
00987   // reason, we must always go through NH.
00988   DN = 0;
00989   for (unsigned i = 0, e = SN->getNumLinks(); i != e; ++i) {
00990     const DSNodeHandle &SrcEdge = SN->getLink(i << DS::PointerShift);
00991     if (!SrcEdge.isNull()) {
00992       const DSNodeHandle &DestEdge = getClonedNH(SrcEdge);
00993       // Compute the offset into the current node at which to
00994       // merge this link.  In the common case, this is a linear
00995       // relation to the offset in the original node (with
00996       // wrapping), but if the current node gets collapsed due to
00997       // recursive merging, we must make sure to merge in all remaining
00998       // links at offset zero.
00999       unsigned MergeOffset = 0;
01000       DSNode *CN = NH.getNode();
01001       if (CN->getSize() != 1)
01002         MergeOffset = ((i << DS::PointerShift)+NH.getOffset()) % CN->getSize();
01003       CN->addEdgeTo(MergeOffset, DestEdge);
01004     }
01005   }
01006 
01007   // If this node contains any globals, make sure they end up in the scalar
01008   // map with the correct offset.
01009   for (DSNode::globals_iterator I = SN->globals_begin(), E = SN->globals_end();
01010        I != E; ++I) {
01011     GlobalValue *GV = *I;
01012     const DSNodeHandle &SrcGNH = Src.getNodeForValue(GV);
01013     DSNodeHandle &DestGNH = NodeMap[SrcGNH.getNode()];
01014     assert(DestGNH.getNode() == NH.getNode() &&"Global mapping inconsistent");
01015     Dest.getNodeForValue(GV).mergeWith(DSNodeHandle(DestGNH.getNode(),
01016                                        DestGNH.getOffset()+SrcGNH.getOffset()));
01017   }
01018   NH.getNode()->mergeGlobals(SN->getGlobalsList());
01019 
01020   return DSNodeHandle(NH.getNode(), NH.getOffset()+SrcNH.getOffset());
01021 }
01022 
01023 void ReachabilityCloner::merge(const DSNodeHandle &NH,
01024                                const DSNodeHandle &SrcNH) {
01025   if (SrcNH.isNull()) return;  // Noop
01026   if (NH.isNull()) {
01027     // If there is no destination node, just clone the source and assign the
01028     // destination node to be it.
01029     NH.mergeWith(getClonedNH(SrcNH));
01030     return;
01031   }
01032 
01033   // Okay, at this point, we know that we have both a destination and a source
01034   // node that need to be merged.  Check to see if the source node has already
01035   // been cloned.
01036   const DSNode *SN = SrcNH.getNode();
01037   DSNodeHandle &SCNH = NodeMap[SN];  // SourceClonedNodeHandle
01038   if (!SCNH.isNull()) {   // Node already cloned?
01039     DSNode *SCNHN = SCNH.getNode();
01040     NH.mergeWith(DSNodeHandle(SCNHN,
01041                               SCNH.getOffset()+SrcNH.getOffset()));
01042     return;  // Nothing to do!
01043   }
01044 
01045   // Okay, so the source node has not already been cloned.  Instead of creating
01046   // a new DSNode, only to merge it into the one we already have, try to perform
01047   // the merge in-place.  The only case we cannot handle here is when the offset
01048   // into the existing node is less than the offset into the virtual node we are
01049   // merging in.  In this case, we have to extend the existing node, which
01050   // requires an allocation anyway.
01051   DSNode *DN = NH.getNode();   // Make sure the Offset is up-to-date
01052   if (NH.getOffset() >= SrcNH.getOffset()) {
01053     if (!DN->isNodeCompletelyFolded()) {
01054       // Make sure the destination node is folded if the source node is folded.
01055       if (SN->isNodeCompletelyFolded()) {
01056         DN->foldNodeCompletely();
01057         DN = NH.getNode();
01058       } else if (SN->getSize() != DN->getSize()) {
01059         // If the two nodes are of different size, and the smaller node has the
01060         // array bit set, collapse!
01061 #if COLLAPSE_ARRAYS_AGGRESSIVELY
01062         if (SN->getSize() < DN->getSize()) {
01063           if (SN->isArray()) {
01064             DN->foldNodeCompletely();
01065             DN = NH.getNode();
01066           }
01067         } else if (DN->isArray()) {
01068           DN->foldNodeCompletely();
01069           DN = NH.getNode();
01070         }
01071 #endif
01072       }
01073 
01074       // Merge the type entries of the two nodes together...
01075       if (SN->getType() != Type::VoidTy && !DN->isNodeCompletelyFolded()) {
01076         DN->mergeTypeInfo(SN->getType(), NH.getOffset()-SrcNH.getOffset());
01077         DN = NH.getNode();
01078       }
01079     }
01080 
01081     assert(!DN->isDeadNode());
01082 
01083     // Merge the NodeType information.
01084     DN->mergeNodeFlags(SN->getNodeFlags() & BitsToKeep);
01085 
01086     // Before we start merging outgoing links and updating the scalar map, make
01087     // sure it is known that this is the representative node for the src node.
01088     SCNH = DSNodeHandle(DN, NH.getOffset()-SrcNH.getOffset());
01089 
01090     // If the source node contains any globals, make sure they end up in the
01091     // scalar map with the correct offset.
01092     if (SN->globals_begin() != SN->globals_end()) {
01093       // Update the globals in the destination node itself.
01094       DN->mergeGlobals(SN->getGlobalsList());
01095 
01096       // Update the scalar map for the graph we are merging the source node
01097       // into.
01098       for (DSNode::globals_iterator I = SN->globals_begin(),
01099              E = SN->globals_end(); I != E; ++I) {
01100         GlobalValue *GV = *I;
01101         const DSNodeHandle &SrcGNH = Src.getNodeForValue(GV);
01102         DSNodeHandle &DestGNH = NodeMap[SrcGNH.getNode()];
01103         assert(DestGNH.getNode()==NH.getNode() &&"Global mapping inconsistent");
01104         Dest.getNodeForValue(GV).mergeWith(DSNodeHandle(DestGNH.getNode(),
01105                                       DestGNH.getOffset()+SrcGNH.getOffset()));
01106       }
01107       NH.getNode()->mergeGlobals(SN->getGlobalsList());
01108     }
01109   } else {
01110     // We cannot handle this case without allocating a temporary node.  Fall
01111     // back on being simple.
01112     DSNode *NewDN = new DSNode(*SN, &Dest, true /* Null out all links */);
01113     NewDN->maskNodeTypes(BitsToKeep);
01114 
01115     unsigned NHOffset = NH.getOffset();
01116     NH.mergeWith(DSNodeHandle(NewDN, SrcNH.getOffset()));
01117 
01118     assert(NH.getNode() &&
01119            (NH.getOffset() > NHOffset ||
01120             (NH.getOffset() == 0 && NH.getNode()->isNodeCompletelyFolded())) &&
01121            "Merging did not adjust the offset!");
01122 
01123     // Before we start merging outgoing links and updating the scalar map, make
01124     // sure it is known that this is the representative node for the src node.
01125     SCNH = DSNodeHandle(NH.getNode(), NH.getOffset()-SrcNH.getOffset());
01126 
01127     // If the source node contained any globals, make sure to create entries
01128     // in the scalar map for them!
01129     for (DSNode::globals_iterator I = SN->globals_begin(),
01130            E = SN->globals_end(); I != E; ++I) {
01131       GlobalValue *GV = *I;
01132       const DSNodeHandle &SrcGNH = Src.getNodeForValue(GV);
01133       DSNodeHandle &DestGNH = NodeMap[SrcGNH.getNode()];
01134       assert(DestGNH.getNode()==NH.getNode() &&"Global mapping inconsistent");
01135       assert(SrcGNH.getNode() == SN && "Global mapping inconsistent");
01136       Dest.getNodeForValue(GV).mergeWith(DSNodeHandle(DestGNH.getNode(),
01137                                     DestGNH.getOffset()+SrcGNH.getOffset()));
01138     }
01139   }
01140 
01141 
01142   // Next, recursively merge all outgoing links as necessary.  Note that
01143   // adding these links can cause the destination node to collapse itself at
01144   // any time, and the current node may be merged with arbitrary other nodes.
01145   // For this reason, we must always go through NH.
01146   DN = 0;
01147   for (unsigned i = 0, e = SN->getNumLinks(); i != e; ++i) {
01148     const DSNodeHandle &SrcEdge = SN->getLink(i << DS::PointerShift);
01149     if (!SrcEdge.isNull()) {
01150       // Compute the offset into the current node at which to
01151       // merge this link.  In the common case, this is a linear
01152       // relation to the offset in the original node (with
01153       // wrapping), but if the current node gets collapsed due to
01154       // recursive merging, we must make sure to merge in all remaining
01155       // links at offset zero.
01156       DSNode *CN = SCNH.getNode();
01157       unsigned MergeOffset =
01158         ((i << DS::PointerShift)+SCNH.getOffset()) % CN->getSize();
01159 
01160       DSNodeHandle Tmp = CN->getLink(MergeOffset);
01161       if (!Tmp.isNull()) {
01162         // Perform the recursive merging.  Make sure to create a temporary NH,
01163         // because the Link can disappear in the process of recursive merging.
01164         merge(Tmp, SrcEdge);
01165       } else {
01166         Tmp.mergeWith(getClonedNH(SrcEdge));
01167         // Merging this could cause all kinds of recursive things to happen,
01168         // culminating in the current node being eliminated.  Since this is
01169         // possible, make sure to reaquire the link from 'CN'.
01170 
01171         unsigned MergeOffset = 0;
01172         CN = SCNH.getNode();
01173         MergeOffset = ((i << DS::PointerShift)+SCNH.getOffset()) %CN->getSize();
01174         CN->getLink(MergeOffset).mergeWith(Tmp);
01175       }
01176     }
01177   }
01178 }
01179 
01180 /// mergeCallSite - Merge the nodes reachable from the specified src call
01181 /// site into the nodes reachable from DestCS.
01182 void ReachabilityCloner::mergeCallSite(DSCallSite &DestCS,
01183                                        const DSCallSite &SrcCS) {
01184   merge(DestCS.getRetVal(), SrcCS.getRetVal());
01185   unsigned MinArgs = DestCS.getNumPtrArgs();
01186   if (SrcCS.getNumPtrArgs() < MinArgs) MinArgs = SrcCS.getNumPtrArgs();
01187 
01188   for (unsigned a = 0; a != MinArgs; ++a)
01189     merge(DestCS.getPtrArg(a), SrcCS.getPtrArg(a));
01190 
01191   for (unsigned a = MinArgs, e = SrcCS.getNumPtrArgs(); a != e; ++a)
01192     DestCS.addPtrArg(getClonedNH(SrcCS.getPtrArg(a)));
01193 }
01194 
01195 
01196 //===----------------------------------------------------------------------===//
01197 // DSCallSite Implementation
01198 //===----------------------------------------------------------------------===//
01199 
01200 // Define here to avoid including iOther.h and BasicBlock.h in DSGraph.h
01201 Function &DSCallSite::getCaller() const {
01202   return *Site.getInstruction()->getParent()->getParent();
01203 }
01204 
01205 void DSCallSite::InitNH(DSNodeHandle &NH, const DSNodeHandle &Src,
01206                         ReachabilityCloner &RC) {
01207   NH = RC.getClonedNH(Src);
01208 }
01209 
01210 //===----------------------------------------------------------------------===//
01211 // DSGraph Implementation
01212 //===----------------------------------------------------------------------===//
01213 
01214 /// getFunctionNames - Return a space separated list of the name of the
01215 /// functions in this graph (if any)
01216 std::string DSGraph::getFunctionNames() const {
01217   switch (getReturnNodes().size()) {
01218   case 0: return "Globals graph";
01219   case 1: return retnodes_begin()->first->getName();
01220   default:
01221     std::string Return;
01222     for (DSGraph::retnodes_iterator I = retnodes_begin();
01223          I != retnodes_end(); ++I)
01224       Return += I->first->getName() + " ";
01225     Return.erase(Return.end()-1, Return.end());   // Remove last space character
01226     return Return;
01227   }
01228 }
01229 
01230 
01231 DSGraph::DSGraph(const DSGraph &G, EquivalenceClasses<GlobalValue*> &ECs,
01232                  unsigned CloneFlags)
01233   : GlobalsGraph(0), ScalarMap(ECs), TD(G.TD) {
01234   PrintAuxCalls = false;
01235   cloneInto(G, CloneFlags);
01236 }
01237 
01238 DSGraph::~DSGraph() {
01239   FunctionCalls.clear();
01240   AuxFunctionCalls.clear();
01241   ScalarMap.clear();
01242   ReturnNodes.clear();
01243 
01244   // Drop all intra-node references, so that assertions don't fail...
01245   for (node_iterator NI = node_begin(), E = node_end(); NI != E; ++NI)
01246     NI->dropAllReferences();
01247 
01248   // Free all of the nodes.
01249   Nodes.clear();
01250 }
01251 
01252 // dump - Allow inspection of graph in a debugger.
01253 void DSGraph::dump() const { print(std::cerr); }
01254 
01255 
01256 /// remapLinks - Change all of the Links in the current node according to the
01257 /// specified mapping.
01258 ///
01259 void DSNode::remapLinks(DSGraph::NodeMapTy &OldNodeMap) {
01260   for (unsigned i = 0, e = Links.size(); i != e; ++i)
01261     if (DSNode *N = Links[i].getNode()) {
01262       DSGraph::NodeMapTy::const_iterator ONMI = OldNodeMap.find(N);
01263       if (ONMI != OldNodeMap.end()) {
01264         DSNode *ONMIN = ONMI->second.getNode();
01265         Links[i].setTo(ONMIN, Links[i].getOffset()+ONMI->second.getOffset());
01266       }
01267     }
01268 }
01269 
01270 /// addObjectToGraph - This method can be used to add global, stack, and heap
01271 /// objects to the graph.  This can be used when updating DSGraphs due to the
01272 /// introduction of new temporary objects.  The new object is not pointed to
01273 /// and does not point to any other objects in the graph.
01274 DSNode *DSGraph::addObjectToGraph(Value *Ptr, bool UseDeclaredType) {
01275   assert(isa<PointerType>(Ptr->getType()) && "Ptr is not a pointer!");
01276   const Type *Ty = cast<PointerType>(Ptr->getType())->getElementType();
01277   DSNode *N = new DSNode(UseDeclaredType ? Ty : 0, this);
01278   assert(ScalarMap[Ptr].isNull() && "Object already in this graph!");
01279   ScalarMap[Ptr] = N;
01280 
01281   if (GlobalValue *GV = dyn_cast<GlobalValue>(Ptr)) {
01282     N->addGlobal(GV);
01283   } else if (MallocInst *MI = dyn_cast<MallocInst>(Ptr)) {
01284     N->setHeapNodeMarker();
01285   } else if (AllocaInst *AI = dyn_cast<AllocaInst>(Ptr)) {
01286     N->setAllocaNodeMarker();
01287   } else {
01288     assert(0 && "Illegal memory object input!");
01289   }
01290   return N;
01291 }
01292 
01293 
01294 /// cloneInto - Clone the specified DSGraph into the current graph.  The
01295 /// translated ScalarMap for the old function is filled into the ScalarMap
01296 /// for the graph, and the translated ReturnNodes map is returned into
01297 /// ReturnNodes.
01298 ///
01299 /// The CloneFlags member controls various aspects of the cloning process.
01300 ///
01301 void DSGraph::cloneInto(const DSGraph &G, unsigned CloneFlags) {
01302   TIME_REGION(X, "cloneInto");
01303   assert(&G != this && "Cannot clone graph into itself!");
01304 
01305   NodeMapTy OldNodeMap;
01306 
01307   // Remove alloca or mod/ref bits as specified...
01308   unsigned BitsToClear = ((CloneFlags & StripAllocaBit)? DSNode::AllocaNode : 0)
01309     | ((CloneFlags & StripModRefBits)? (DSNode::Modified | DSNode::Read) : 0)
01310     | ((CloneFlags & StripIncompleteBit)? DSNode::Incomplete : 0);
01311   BitsToClear |= DSNode::DEAD;  // Clear dead flag...
01312 
01313   for (node_const_iterator I = G.node_begin(), E = G.node_end(); I != E; ++I) {
01314     assert(!I->isForwarding() &&
01315            "Forward nodes shouldn't be in node list!");
01316     DSNode *New = new DSNode(*I, this);
01317     New->maskNodeTypes(~BitsToClear);
01318     OldNodeMap[I] = New;
01319   }
01320 
01321 #ifndef NDEBUG
01322   Timer::addPeakMemoryMeasurement();
01323 #endif
01324 
01325   // Rewrite the links in the new nodes to point into the current graph now.
01326   // Note that we don't loop over the node's list to do this.  The problem is
01327   // that remaping links can cause recursive merging to happen, which means
01328   // that node_iterator's can get easily invalidated!  Because of this, we
01329   // loop over the OldNodeMap, which contains all of the new nodes as the
01330   // .second element of the map elements.  Also note that if we remap a node
01331   // more than once, we won't break anything.
01332   for (NodeMapTy::iterator I = OldNodeMap.begin(), E = OldNodeMap.end();
01333        I != E; ++I)
01334     I->second.getNode()->remapLinks(OldNodeMap);
01335 
01336   // Copy the scalar map... merging all of the global nodes...
01337   for (DSScalarMap::const_iterator I = G.ScalarMap.begin(),
01338          E = G.ScalarMap.end(); I != E; ++I) {
01339     DSNodeHandle &MappedNode = OldNodeMap[I->second.getNode()];
01340     DSNodeHandle &H = ScalarMap.getRawEntryRef(I->first);
01341     DSNode *MappedNodeN = MappedNode.getNode();
01342     H.mergeWith(DSNodeHandle(MappedNodeN,
01343                              I->second.getOffset()+MappedNode.getOffset()));
01344   }
01345 
01346   if (!(CloneFlags & DontCloneCallNodes)) {
01347     // Copy the function calls list.
01348     for (fc_iterator I = G.fc_begin(), E = G.fc_end(); I != E; ++I)
01349       FunctionCalls.push_back(DSCallSite(*I, OldNodeMap));
01350   }
01351 
01352   if (!(CloneFlags & DontCloneAuxCallNodes)) {
01353     // Copy the auxiliary function calls list.
01354     for (afc_iterator I = G.afc_begin(), E = G.afc_end(); I != E; ++I)
01355       AuxFunctionCalls.push_back(DSCallSite(*I, OldNodeMap));
01356   }
01357 
01358   // Map the return node pointers over...
01359   for (retnodes_iterator I = G.retnodes_begin(),
01360          E = G.retnodes_end(); I != E; ++I) {
01361     const DSNodeHandle &Ret = I->second;
01362     DSNodeHandle &MappedRet = OldNodeMap[Ret.getNode()];
01363     DSNode *MappedRetN = MappedRet.getNode();
01364     ReturnNodes.insert(std::make_pair(I->first,
01365                                       DSNodeHandle(MappedRetN,
01366                                      MappedRet.getOffset()+Ret.getOffset())));
01367   }
01368 }
01369 
01370 /// spliceFrom - Logically perform the operation of cloning the RHS graph into
01371 /// this graph, then clearing the RHS graph.  Instead of performing this as
01372 /// two seperate operations, do it as a single, much faster, one.
01373 ///
01374 void DSGraph::spliceFrom(DSGraph &RHS) {
01375   // Change all of the nodes in RHS to think we are their parent.
01376   for (NodeListTy::iterator I = RHS.Nodes.begin(), E = RHS.Nodes.end();
01377        I != E; ++I)
01378     I->setParentGraph(this);
01379   // Take all of the nodes.
01380   Nodes.splice(Nodes.end(), RHS.Nodes);
01381 
01382   // Take all of the calls.
01383   FunctionCalls.splice(FunctionCalls.end(), RHS.FunctionCalls);
01384   AuxFunctionCalls.splice(AuxFunctionCalls.end(), RHS.AuxFunctionCalls);
01385 
01386   // Take all of the return nodes.
01387   if (ReturnNodes.empty()) {
01388     ReturnNodes.swap(RHS.ReturnNodes);
01389   } else {
01390     ReturnNodes.insert(RHS.ReturnNodes.begin(), RHS.ReturnNodes.end());
01391     RHS.ReturnNodes.clear();
01392   }
01393 
01394   // Merge the scalar map in.
01395   ScalarMap.spliceFrom(RHS.ScalarMap);
01396 }
01397 
01398 /// spliceFrom - Copy all entries from RHS, then clear RHS.
01399 ///
01400 void DSScalarMap::spliceFrom(DSScalarMap &RHS) {
01401   // Special case if this is empty.
01402   if (ValueMap.empty()) {
01403     ValueMap.swap(RHS.ValueMap);
01404     GlobalSet.swap(RHS.GlobalSet);
01405   } else {
01406     GlobalSet.insert(RHS.GlobalSet.begin(), RHS.GlobalSet.end());
01407     for (ValueMapTy::iterator I = RHS.ValueMap.begin(), E = RHS.ValueMap.end();
01408          I != E; ++I)
01409       ValueMap[I->first].mergeWith(I->second);
01410     RHS.ValueMap.clear();
01411   }
01412 }
01413 
01414 
01415 /// getFunctionArgumentsForCall - Given a function that is currently in this
01416 /// graph, return the DSNodeHandles that correspond to the pointer-compatible
01417 /// function arguments.  The vector is filled in with the return value (or
01418 /// null if it is not pointer compatible), followed by all of the
01419 /// pointer-compatible arguments.
01420 void DSGraph::getFunctionArgumentsForCall(Function *F,
01421                                        std::vector<DSNodeHandle> &Args) const {
01422   Args.push_back(getReturnNodeFor(*F));
01423   for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
01424        AI != E; ++AI)
01425     if (isPointerType(AI->getType())) {
01426       Args.push_back(getNodeForValue(AI));
01427       assert(!Args.back().isNull() && "Pointer argument w/o scalarmap entry!?");
01428     }
01429 }
01430 
01431 namespace {
01432   // HackedGraphSCCFinder - This is used to find nodes that have a path from the
01433   // node to a node cloned by the ReachabilityCloner object contained.  To be
01434   // extra obnoxious it ignores edges from nodes that are globals, and truncates
01435   // search at RC marked nodes.  This is designed as an object so that
01436   // intermediate results can be memoized across invocations of
01437   // PathExistsToClonedNode.
01438   struct HackedGraphSCCFinder {
01439     ReachabilityCloner &RC;
01440     unsigned CurNodeId;
01441     std::vector<const DSNode*> SCCStack;
01442     std::map<const DSNode*, std::pair<unsigned, bool> > NodeInfo;
01443 
01444     HackedGraphSCCFinder(ReachabilityCloner &rc) : RC(rc), CurNodeId(1) {
01445       // Remove null pointer as a special case.
01446       NodeInfo[0] = std::make_pair(0, false);
01447     }
01448 
01449     std::pair<unsigned, bool> &VisitForSCCs(const DSNode *N);
01450 
01451     bool PathExistsToClonedNode(const DSNode *N) {
01452       return VisitForSCCs(N).second;
01453     }
01454 
01455     bool PathExistsToClonedNode(const DSCallSite &CS) {
01456       if (PathExistsToClonedNode(CS.getRetVal().getNode()))
01457         return true;
01458       for (unsigned i = 0, e = CS.getNumPtrArgs(); i != e; ++i)
01459         if (PathExistsToClonedNode(CS.getPtrArg(i).getNode()))
01460           return true;
01461       return false;
01462     }
01463   };
01464 }
01465 
01466 std::pair<unsigned, bool> &HackedGraphSCCFinder::
01467 VisitForSCCs(const DSNode *N) {
01468   std::map<const DSNode*, std::pair<unsigned, bool> >::iterator
01469     NodeInfoIt = NodeInfo.lower_bound(N);
01470   if (NodeInfoIt != NodeInfo.end() && NodeInfoIt->first == N)
01471     return NodeInfoIt->second;
01472 
01473   unsigned Min = CurNodeId++;
01474   unsigned MyId = Min;
01475   std::pair<unsigned, bool> &ThisNodeInfo =
01476     NodeInfo.insert(NodeInfoIt,
01477                     std::make_pair(N, std::make_pair(MyId, false)))->second;
01478 
01479   // Base case: if we find a global, this doesn't reach the cloned graph
01480   // portion.
01481   if (N->isGlobalNode()) {
01482     ThisNodeInfo.second = false;
01483     return ThisNodeInfo;
01484   }
01485 
01486   // Base case: if this does reach the cloned graph portion... it does. :)
01487   if (RC.hasClonedNode(N)) {
01488     ThisNodeInfo.second = true;
01489     return ThisNodeInfo;
01490   }
01491 
01492   SCCStack.push_back(N);
01493 
01494   // Otherwise, check all successors.
01495   bool AnyDirectSuccessorsReachClonedNodes = false;
01496   for (DSNode::const_edge_iterator EI = N->edge_begin(), EE = N->edge_end();
01497        EI != EE; ++EI)
01498     if (DSNode *Succ = EI->getNode()) {
01499       std::pair<unsigned, bool> &SuccInfo = VisitForSCCs(Succ);
01500       if (SuccInfo.first < Min) Min = SuccInfo.first;
01501       AnyDirectSuccessorsReachClonedNodes |= SuccInfo.second;
01502     }
01503 
01504   if (Min != MyId)
01505     return ThisNodeInfo;  // Part of a large SCC.  Leave self on stack.
01506 
01507   if (SCCStack.back() == N) {  // Special case single node SCC.
01508     SCCStack.pop_back();
01509     ThisNodeInfo.second = AnyDirectSuccessorsReachClonedNodes;
01510     return ThisNodeInfo;
01511   }
01512 
01513   // Find out if any direct successors of any node reach cloned nodes.
01514   if (!AnyDirectSuccessorsReachClonedNodes)
01515     for (unsigned i = SCCStack.size()-1; SCCStack[i] != N; --i)
01516       for (DSNode::const_edge_iterator EI = N->edge_begin(), EE = N->edge_end();
01517            EI != EE; ++EI)
01518         if (DSNode *N = EI->getNode())
01519           if (NodeInfo[N].second) {
01520             AnyDirectSuccessorsReachClonedNodes = true;
01521             goto OutOfLoop;
01522           }
01523 OutOfLoop:
01524   // If any successor reaches a cloned node, mark all nodes in this SCC as
01525   // reaching the cloned node.
01526   if (AnyDirectSuccessorsReachClonedNodes)
01527     while (SCCStack.back() != N) {
01528       NodeInfo[SCCStack.back()].second = true;
01529       SCCStack.pop_back();
01530     }
01531   SCCStack.pop_back();
01532   ThisNodeInfo.second = true;
01533   return ThisNodeInfo;
01534 }
01535 
01536 /// mergeInCallFromOtherGraph - This graph merges in the minimal number of
01537 /// nodes from G2 into 'this' graph, merging the bindings specified by the
01538 /// call site (in this graph) with the bindings specified by the vector in G2.
01539 /// The two DSGraphs must be different.
01540 ///
01541 void DSGraph::mergeInGraph(const DSCallSite &CS,
01542                            std::vector<DSNodeHandle> &Args,
01543                            const DSGraph &Graph, unsigned CloneFlags) {
01544   TIME_REGION(X, "mergeInGraph");
01545 
01546   assert((CloneFlags & DontCloneCallNodes) &&
01547          "Doesn't support copying of call nodes!");
01548 
01549   // If this is not a recursive call, clone the graph into this graph...
01550   if (&Graph == this) {
01551     // Merge the return value with the return value of the context.
01552     Args[0].mergeWith(CS.getRetVal());
01553 
01554     // Resolve all of the function arguments.
01555     for (unsigned i = 0, e = CS.getNumPtrArgs(); i != e; ++i) {
01556       if (i == Args.size()-1)
01557         break;
01558 
01559       // Add the link from the argument scalar to the provided value.
01560       Args[i+1].mergeWith(CS.getPtrArg(i));
01561     }
01562     return;
01563   }
01564 
01565   // Clone the callee's graph into the current graph, keeping track of where
01566   // scalars in the old graph _used_ to point, and of the new nodes matching
01567   // nodes of the old graph.
01568   ReachabilityCloner RC(*this, Graph, CloneFlags);
01569 
01570   // Map the return node pointer over.
01571   if (!CS.getRetVal().isNull())
01572     RC.merge(CS.getRetVal(), Args[0]);
01573 
01574   // Map over all of the arguments.
01575   for (unsigned i = 0, e = CS.getNumPtrArgs(); i != e; ++i) {
01576     if (i == Args.size()-1)
01577       break;
01578 
01579     // Add the link from the argument scalar to the provided value.
01580     RC.merge(CS.getPtrArg(i), Args[i+1]);
01581   }
01582 
01583   // We generally don't want to copy global nodes or aux calls from the callee
01584   // graph to the caller graph.  However, we have to copy them if there is a
01585   // path from the node to a node we have already copied which does not go
01586   // through another global.  Compute the set of node that can reach globals and
01587   // aux call nodes to copy over, then do it.
01588   std::vector<const DSCallSite*> AuxCallToCopy;
01589   std::vector<GlobalValue*> GlobalsToCopy;
01590 
01591   // NodesReachCopiedNodes - Memoize results for efficiency.  Contains a
01592   // true/false value for every visited node that reaches a copied node without
01593   // going through a global.
01594   HackedGraphSCCFinder SCCFinder(RC);
01595 
01596   if (!(CloneFlags & DontCloneAuxCallNodes))
01597     for (afc_iterator I = Graph.afc_begin(), E = Graph.afc_end(); I!=E; ++I)
01598       if (SCCFinder.PathExistsToClonedNode(*I))
01599         AuxCallToCopy.push_back(&*I);
01600       else if (I->isIndirectCall()){
01601   //If the call node doesn't have any callees, clone it
01602   std::vector< Function *> List;
01603   I->getCalleeNode()->addFullFunctionList(List);
01604   if (!List.size())
01605     AuxCallToCopy.push_back(&*I);
01606        }
01607 
01608   const DSScalarMap &GSM = Graph.getScalarMap();
01609   for (DSScalarMap::global_iterator GI = GSM.global_begin(),
01610          E = GSM.global_end(); GI != E; ++GI) {
01611     DSNode *GlobalNode = Graph.getNodeForValue(*GI).getNode();
01612     for (DSNode::edge_iterator EI = GlobalNode->edge_begin(),
01613            EE = GlobalNode->edge_end(); EI != EE; ++EI)
01614       if (SCCFinder.PathExistsToClonedNode(EI->getNode())) {
01615         GlobalsToCopy.push_back(*GI);
01616         break;
01617       }
01618   }
01619 
01620   // Copy aux calls that are needed.
01621   for (unsigned i = 0, e = AuxCallToCopy.size(); i != e; ++i)
01622     AuxFunctionCalls.push_back(DSCallSite(*AuxCallToCopy[i], RC));
01623 
01624   // Copy globals that are needed.
01625   for (unsigned i = 0, e = GlobalsToCopy.size(); i != e; ++i)
01626     RC.getClonedNH(Graph.getNodeForValue(GlobalsToCopy[i]));
01627 }
01628 
01629 
01630 
01631 /// mergeInGraph - The method is used for merging graphs together.  If the
01632 /// argument graph is not *this, it makes a clone of the specified graph, then
01633 /// merges the nodes specified in the call site with the formal arguments in the
01634 /// graph.
01635 ///
01636 void DSGraph::mergeInGraph(const DSCallSite &CS, Function &F,
01637                            const DSGraph &Graph, unsigned CloneFlags) {
01638   // Set up argument bindings.
01639   std::vector<DSNodeHandle> Args;
01640   Graph.getFunctionArgumentsForCall(&F, Args);
01641 
01642   mergeInGraph(CS, Args, Graph, CloneFlags);
01643 }
01644 
01645 /// getCallSiteForArguments - Get the arguments and return value bindings for
01646 /// the specified function in the current graph.
01647 ///
01648 DSCallSite DSGraph::getCallSiteForArguments(Function &F) const {
01649   std::vector<DSNodeHandle> Args;
01650 
01651   for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
01652     if (isPointerType(I->getType()))
01653       Args.push_back(getNodeForValue(I));
01654 
01655   return DSCallSite(CallSite(), getReturnNodeFor(F), &F, Args);
01656 }
01657 
01658 /// getDSCallSiteForCallSite - Given an LLVM CallSite object that is live in
01659 /// the context of this graph, return the DSCallSite for it.
01660 DSCallSite DSGraph::getDSCallSiteForCallSite(CallSite CS) const {
01661   DSNodeHandle RetVal;
01662   Instruction *I = CS.getInstruction();
01663   if (isPointerType(I->getType()))
01664     RetVal = getNodeForValue(I);
01665 
01666   std::vector<DSNodeHandle> Args;
01667   Args.reserve(CS.arg_end()-CS.arg_begin());
01668 
01669   // Calculate the arguments vector...
01670   for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); I != E; ++I)
01671     if (isPointerType((*I)->getType()))
01672       if (isa<ConstantPointerNull>(*I))
01673         Args.push_back(DSNodeHandle());
01674       else
01675         Args.push_back(getNodeForValue(*I));
01676 
01677   // Add a new function call entry...
01678   if (Function *F = CS.getCalledFunction())
01679     return DSCallSite(CS, RetVal, F, Args);
01680   else
01681     return DSCallSite(CS, RetVal,
01682                       getNodeForValue(CS.getCalledValue()).getNode(), Args);
01683 }
01684 
01685 
01686 
01687 // markIncompleteNodes - Mark the specified node as having contents that are not
01688 // known with the current analysis we have performed.  Because a node makes all
01689 // of the nodes it can reach incomplete if the node itself is incomplete, we
01690 // must recursively traverse the data structure graph, marking all reachable
01691 // nodes as incomplete.
01692 //
01693 static void markIncompleteNode(DSNode *N) {
01694   // Stop recursion if no node, or if node already marked...
01695   if (N == 0 || N->isIncomplete()) return;
01696 
01697   // Actually mark the node
01698   N->setIncompleteMarker();
01699 
01700   // Recursively process children...
01701   for (DSNode::edge_iterator I = N->edge_begin(),E = N->edge_end(); I != E; ++I)
01702     if (DSNode *DSN = I->getNode())
01703       markIncompleteNode(DSN);
01704 }
01705 
01706 static void markIncomplete(DSCallSite &Call) {
01707   // Then the return value is certainly incomplete!
01708   markIncompleteNode(Call.getRetVal().getNode());
01709 
01710   // All objects pointed to by function arguments are incomplete!
01711   for (unsigned i = 0, e = Call.getNumPtrArgs(); i != e; ++i)
01712     markIncompleteNode(Call.getPtrArg(i).getNode());
01713 }
01714 
01715 // markIncompleteNodes - Traverse the graph, identifying nodes that may be
01716 // modified by other functions that have not been resolved yet.  This marks
01717 // nodes that are reachable through three sources of "unknownness":
01718 //
01719 //  Global Variables, Function Calls, and Incoming Arguments
01720 //
01721 // For any node that may have unknown components (because something outside the
01722 // scope of current analysis may have modified it), the 'Incomplete' flag is
01723 // added to the NodeType.
01724 //
01725 void DSGraph::markIncompleteNodes(unsigned Flags) {
01726   // Mark any incoming arguments as incomplete.
01727   if (Flags & DSGraph::MarkFormalArgs)
01728     for (ReturnNodesTy::iterator FI = ReturnNodes.begin(), E =ReturnNodes.end();
01729          FI != E; ++FI) {
01730       Function &F = *FI->first;
01731       for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end();
01732            I != E; ++I)
01733         if (isPointerType(I->getType()))
01734           markIncompleteNode(getNodeForValue(I).getNode());
01735       markIncompleteNode(FI->second.getNode());
01736     }
01737 
01738   // Mark stuff passed into functions calls as being incomplete.
01739   if (!shouldPrintAuxCalls())
01740     for (std::list<DSCallSite>::iterator I = FunctionCalls.begin(),
01741            E = FunctionCalls.end(); I != E; ++I)
01742       markIncomplete(*I);
01743   else
01744     for (std::list<DSCallSite>::iterator I = AuxFunctionCalls.begin(),
01745            E = AuxFunctionCalls.end(); I != E; ++I)
01746       markIncomplete(*I);
01747 
01748   // Mark all global nodes as incomplete.
01749   for (DSScalarMap::global_iterator I = ScalarMap.global_begin(),
01750          E = ScalarMap.global_end(); I != E; ++I)
01751     if (GlobalVariable *GV = dyn_cast<GlobalVariable>(*I))
01752       if (!GV->hasInitializer() ||    // Always mark external globals incomp.
01753           (!GV->isConstant() && (Flags & DSGraph::IgnoreGlobals) == 0))
01754         markIncompleteNode(ScalarMap[GV].getNode());
01755 }
01756 
01757 static inline void killIfUselessEdge(DSNodeHandle &Edge) {
01758   if (DSNode *N = Edge.getNode())  // Is there an edge?
01759     if (N->getNumReferrers() == 1)  // Does it point to a lonely node?
01760       // No interesting info?
01761       if ((N->getNodeFlags() & ~DSNode::Incomplete) == 0 &&
01762           N->getType() == Type::VoidTy && !N->isNodeCompletelyFolded())
01763         Edge.setTo(0, 0);  // Kill the edge!
01764 }
01765 
01766 static inline bool nodeContainsExternalFunction(const DSNode *N) {
01767   std::vector<Function*> Funcs;
01768   N->addFullFunctionList(Funcs);
01769   for (unsigned i = 0, e = Funcs.size(); i != e; ++i)
01770     if (Funcs[i]->isExternal()) return true;
01771   return false;
01772 }
01773 
01774 static void removeIdenticalCalls(std::list<DSCallSite> &Calls) {
01775   // Remove trivially identical function calls
01776   Calls.sort();  // Sort by callee as primary key!
01777 
01778   // Scan the call list cleaning it up as necessary...
01779   DSNodeHandle LastCalleeNode;
01780   Function *LastCalleeFunc = 0;
01781   unsigned NumDuplicateCalls = 0;
01782   bool LastCalleeContainsExternalFunction = false;
01783 
01784   unsigned NumDeleted = 0;
01785   for (std::list<DSCallSite>::iterator I = Calls.begin(), E = Calls.end();
01786        I != E;) {
01787     DSCallSite &CS = *I;
01788     std::list<DSCallSite>::iterator OldIt = I++;
01789 
01790     if (!CS.isIndirectCall()) {
01791       LastCalleeNode = 0;
01792     } else {
01793       DSNode *Callee = CS.getCalleeNode();
01794 
01795       // If the Callee is a useless edge, this must be an unreachable call site,
01796       // eliminate it.
01797       if (Callee->getNumReferrers() == 1 && Callee->isComplete() &&
01798           Callee->getGlobalsList().empty()) {  // No useful info?
01799 #ifndef NDEBUG
01800         std::cerr << "WARNING: Useless call site found.\n";
01801 #endif
01802         Calls.erase(OldIt);
01803         ++NumDeleted;
01804         continue;
01805       }
01806 
01807       // If the last call site in the list has the same callee as this one, and
01808       // if the callee contains an external function, it will never be
01809       // resolvable, just merge the call sites.
01810       if (!LastCalleeNode.isNull() && LastCalleeNode.getNode() == Callee) {
01811         LastCalleeContainsExternalFunction =
01812           nodeContainsExternalFunction(Callee);
01813 
01814         std::list<DSCallSite>::iterator PrevIt = OldIt;
01815         --PrevIt;
01816         PrevIt->mergeWith(CS);
01817 
01818         // No need to keep this call anymore.
01819         Calls.erase(OldIt);
01820         ++NumDeleted;
01821         continue;
01822       } else {
01823         LastCalleeNode = Callee;
01824       }
01825     }
01826 
01827     // If the return value or any arguments point to a void node with no
01828     // information at all in it, and the call node is the only node to point
01829     // to it, remove the edge to the node (killing the node).
01830     //
01831     killIfUselessEdge(CS.getRetVal());
01832     for (unsigned a = 0, e = CS.getNumPtrArgs(); a != e; ++a)
01833       killIfUselessEdge(CS.getPtrArg(a));
01834 
01835 #if 0
01836     // If this call site calls the same function as the last call site, and if
01837     // the function pointer contains an external function, this node will
01838     // never be resolved.  Merge the arguments of the call node because no
01839     // information will be lost.
01840     //
01841     if ((CS.isDirectCall()   && CS.getCalleeFunc() == LastCalleeFunc) ||
01842         (CS.isIndirectCall() && CS.getCalleeNode() == LastCalleeNode)) {
01843       ++NumDuplicateCalls;
01844       if (NumDuplicateCalls == 1) {
01845         if (LastCalleeNode)
01846           LastCalleeContainsExternalFunction =
01847             nodeContainsExternalFunction(LastCalleeNode);
01848         else
01849           LastCalleeContainsExternalFunction = LastCalleeFunc->isExternal();
01850       }
01851 
01852       // It is not clear why, but enabling this code makes DSA really
01853       // sensitive to node forwarding.  Basically, with this enabled, DSA
01854       // performs different number of inlinings based on which nodes are
01855       // forwarding or not.  This is clearly a problem, so this code is
01856       // disabled until this can be resolved.
01857 #if 1
01858       if (LastCalleeContainsExternalFunction
01859 #if 0
01860           ||
01861           // This should be more than enough context sensitivity!
01862           // FIXME: Evaluate how many times this is tripped!
01863           NumDuplicateCalls > 20
01864 #endif
01865           ) {
01866 
01867         std::list<DSCallSite>::iterator PrevIt = OldIt;
01868         --PrevIt;
01869         PrevIt->mergeWith(CS);
01870 
01871         // No need to keep this call anymore.
01872         Calls.erase(OldIt);
01873         ++NumDeleted;
01874         continue;
01875       }
01876 #endif
01877     } else {
01878       if (CS.isDirectCall()) {
01879         LastCalleeFunc = CS.getCalleeFunc();
01880         LastCalleeNode = 0;
01881       } else {
01882         LastCalleeNode = CS.getCalleeNode();
01883         LastCalleeFunc = 0;
01884       }
01885       NumDuplicateCalls = 0;
01886     }
01887 #endif
01888 
01889     if (I != Calls.end() && CS == *I) {
01890       LastCalleeNode = 0;
01891       Calls.erase(OldIt);
01892       ++NumDeleted;
01893       continue;
01894     }
01895   }
01896 
01897   // Resort now that we simplified things.
01898   Calls.sort();
01899 
01900   // Now that we are in sorted order, eliminate duplicates.
01901   std::list<DSCallSite>::iterator CI = Calls.begin(), CE = Calls.end();
01902   if (CI != CE)
01903     while (1) {
01904       std::list<DSCallSite>::iterator OldIt = CI++;
01905       if (CI == CE) break;
01906 
01907       // If this call site is now the same as the previous one, we can delete it
01908       // as a duplicate.
01909       if (*OldIt == *CI) {
01910         Calls.erase(CI);
01911         CI = OldIt;
01912         ++NumDeleted;
01913       }
01914     }
01915 
01916   //Calls.erase(std::unique(Calls.begin(), Calls.end()), Calls.end());
01917 
01918   // Track the number of call nodes merged away...
01919   NumCallNodesMerged += NumDeleted;
01920 
01921   DEBUG(if (NumDeleted)
01922           std::cerr << "Merged " << NumDeleted << " call nodes.\n";);
01923 }
01924 
01925 
01926 // removeTriviallyDeadNodes - After the graph has been constructed, this method
01927 // removes all unreachable nodes that are created because they got merged with
01928 // other nodes in the graph.  These nodes will all be trivially unreachable, so
01929 // we don't have to perform any non-trivial analysis here.
01930 //
01931 void DSGraph::removeTriviallyDeadNodes() {
01932   TIME_REGION(X, "removeTriviallyDeadNodes");
01933 
01934 #if 0
01935   /// NOTE: This code is disabled.  This slows down DSA on 177.mesa
01936   /// substantially!
01937 
01938   // Loop over all of the nodes in the graph, calling getNode on each field.
01939   // This will cause all nodes to update their forwarding edges, causing
01940   // forwarded nodes to be delete-able.
01941   { TIME_REGION(X, "removeTriviallyDeadNodes:node_iterate");
01942   for (node_iterator NI = node_begin(), E = node_end(); NI != E; ++NI) {
01943     DSNode &N = *NI;
01944     for (unsigned l = 0, e = N.getNumLinks(); l != e; ++l)
01945       N.getLink(l*N.getPointerSize()).getNode();
01946   }
01947   }
01948 
01949   // NOTE: This code is disabled.  Though it should, in theory, allow us to
01950   // remove more nodes down below, the scan of the scalar map is incredibly
01951   // expensive for certain programs (with large SCCs).  In the future, if we can
01952   // make the scalar map scan more efficient, then we can reenable this.
01953   { TIME_REGION(X, "removeTriviallyDeadNodes:scalarmap");
01954 
01955   // Likewise, forward any edges from the scalar nodes.  While we are at it,
01956   // clean house a bit.
01957   for (DSScalarMap::iterator I = ScalarMap.begin(),E = ScalarMap.end();I != E;){
01958     I->second.getNode();
01959     ++I;
01960   }
01961   }
01962 #endif
01963   bool isGlobalsGraph = !GlobalsGraph;
01964 
01965   for (NodeListTy::iterator NI = Nodes.begin(), E = Nodes.end(); NI != E; ) {
01966     DSNode &Node = *NI;
01967 
01968     // Do not remove *any* global nodes in the globals graph.
01969     // This is a special case because such nodes may not have I, M, R flags set.
01970     if (Node.isGlobalNode() && isGlobalsGraph) {
01971       ++NI;
01972       continue;
01973     }
01974 
01975     if (Node.isComplete() && !Node.isModified() && !Node.isRead()) {
01976       // This is a useless node if it has no mod/ref info (checked above),
01977       // outgoing edges (which it cannot, as it is not modified in this
01978       // context), and it has no incoming edges.  If it is a global node it may
01979       // have all of these properties and still have incoming edges, due to the
01980       // scalar map, so we check those now.
01981       //
01982       if (Node.getNumReferrers() == Node.getGlobalsList().size()) {
01983         const std::vector<GlobalValue*> &Globals = Node.getGlobalsList();
01984 
01985         // Loop through and make sure all of the globals are referring directly
01986         // to the node...
01987         for (unsigned j = 0, e = Globals.size(); j != e; ++j) {
01988           DSNode *N = getNodeForValue(Globals[j]).getNode();
01989           assert(N == &Node && "ScalarMap doesn't match globals list!");
01990         }
01991 
01992         // Make sure NumReferrers still agrees, if so, the node is truly dead.
01993         if (Node.getNumReferrers() == Globals.size()) {
01994           for (unsigned j = 0, e = Globals.size(); j != e; ++j)
01995             ScalarMap.erase(Globals[j]);
01996           Node.makeNodeDead();
01997           ++NumTrivialGlobalDNE;
01998         }
01999       }
02000     }
02001 
02002     if (Node.getNodeFlags() == 0 && Node.hasNoReferrers()) {
02003       // This node is dead!
02004       NI = Nodes.erase(NI);    // Erase & remove from node list.
02005       ++NumTrivialDNE;
02006     } else {
02007       ++NI;
02008     }
02009   }
02010 
02011   removeIdenticalCalls(FunctionCalls);
02012   removeIdenticalCalls(AuxFunctionCalls);
02013 }
02014 
02015 
02016 /// markReachableNodes - This method recursively traverses the specified
02017 /// DSNodes, marking any nodes which are reachable.  All reachable nodes it adds
02018 /// to the set, which allows it to only traverse visited nodes once.
02019 ///
02020 void DSNode::markReachableNodes(hash_set<const DSNode*> &ReachableNodes) const {
02021   if (this == 0) return;
02022   assert(getForwardNode() == 0 && "Cannot mark a forwarded node!");
02023   if (ReachableNodes.insert(this).second)        // Is newly reachable?
02024     for (DSNode::const_edge_iterator I = edge_begin(), E = edge_end();
02025          I != E; ++I)
02026       I->getNode()->markReachableNodes(ReachableNodes);
02027 }
02028 
02029 void DSCallSite::markReachableNodes(hash_set<const DSNode*> &Nodes) const {
02030   getRetVal().getNode()->markReachableNodes(Nodes);
02031   if (isIndirectCall()) getCalleeNode()->markReachableNodes(Nodes);
02032 
02033   for (unsigned i = 0, e = getNumPtrArgs(); i != e; ++i)
02034     getPtrArg(i).getNode()->markReachableNodes(Nodes);
02035 }
02036 
02037 // CanReachAliveNodes - Simple graph walker that recursively traverses the graph
02038 // looking for a node that is marked alive.  If an alive node is found, return
02039 // true, otherwise return false.  If an alive node is reachable, this node is
02040 // marked as alive...
02041 //
02042 static bool CanReachAliveNodes(DSNode *N, hash_set<const DSNode*> &Alive,
02043                                hash_set<const DSNode*> &Visited,
02044                                bool IgnoreGlobals) {
02045   if (N == 0) return false;
02046   assert(N->getForwardNode() == 0 && "Cannot mark a forwarded node!");
02047 
02048   // If this is a global node, it will end up in the globals graph anyway, so we
02049   // don't need to worry about it.
02050   if (IgnoreGlobals && N->isGlobalNode()) return false;
02051 
02052   // If we know that this node is alive, return so!
02053   if (Alive.count(N)) return true;
02054 
02055   // Otherwise, we don't think the node is alive yet, check for infinite
02056   // recursion.
02057   if (Visited.count(N)) return false;  // Found a cycle
02058   Visited.insert(N);   // No recursion, insert into Visited...
02059 
02060   for (DSNode::edge_iterator I = N->edge_begin(),E = N->edge_end(); I != E; ++I)
02061     if (CanReachAliveNodes(I->getNode(), Alive, Visited, IgnoreGlobals)) {
02062       N->markReachableNodes(Alive);
02063       return true;
02064     }
02065   return false;
02066 }
02067 
02068 // CallSiteUsesAliveArgs - Return true if the specified call site can reach any
02069 // alive nodes.
02070 //
02071 static bool CallSiteUsesAliveArgs(const DSCallSite &CS,
02072                                   hash_set<const DSNode*> &Alive,
02073                                   hash_set<const DSNode*> &Visited,
02074                                   bool IgnoreGlobals) {
02075   if (CanReachAliveNodes(CS.getRetVal().getNode(), Alive, Visited,
02076                          IgnoreGlobals))
02077     return true;
02078   if (CS.isIndirectCall() &&
02079       CanReachAliveNodes(CS.getCalleeNode(), Alive, Visited, IgnoreGlobals))
02080     return true;
02081   for (unsigned i = 0, e = CS.getNumPtrArgs(); i != e; ++i)
02082     if (CanReachAliveNodes(CS.getPtrArg(i).getNode(), Alive, Visited,
02083                            IgnoreGlobals))
02084       return true;
02085   return false;
02086 }
02087 
02088 // removeDeadNodes - Use a more powerful reachability analysis to eliminate
02089 // subgraphs that are unreachable.  This often occurs because the data
02090 // structure doesn't "escape" into it's caller, and thus should be eliminated
02091 // from the caller's graph entirely.  This is only appropriate to use when
02092 // inlining graphs.
02093 //
02094 void DSGraph::removeDeadNodes(unsigned Flags) {
02095   DEBUG(AssertGraphOK(); if (GlobalsGraph) GlobalsGraph->AssertGraphOK());
02096 
02097   // Reduce the amount of work we have to do... remove dummy nodes left over by
02098   // merging...
02099   removeTriviallyDeadNodes();
02100 
02101   TIME_REGION(X, "removeDeadNodes");
02102 
02103   // FIXME: Merge non-trivially identical call nodes...
02104 
02105   // Alive - a set that holds all nodes found to be reachable/alive.
02106   hash_set<const DSNode*> Alive;
02107   std::vector<std::pair<Value*, DSNode*> > GlobalNodes;
02108 
02109   // Copy and merge all information about globals to the GlobalsGraph if this is
02110   // not a final pass (where unreachable globals are removed).
02111   //
02112   // Strip all alloca bits since the current function is only for the BU pass.
02113   // Strip all incomplete bits since they are short-lived properties and they
02114   // will be correctly computed when rematerializing nodes into the functions.
02115   //
02116   ReachabilityCloner GGCloner(*GlobalsGraph, *this, DSGraph::StripAllocaBit |
02117                               DSGraph::StripIncompleteBit);
02118 
02119   // Mark all nodes reachable by (non-global) scalar nodes as alive...
02120 { TIME_REGION(Y, "removeDeadNodes:scalarscan");
02121   for (DSScalarMap::iterator I = ScalarMap.begin(), E = ScalarMap.end();
02122        I != E; ++I)
02123     if (isa<GlobalValue>(I->first)) {             // Keep track of global nodes
02124       assert(!I->second.isNull() && "Null global node?");
02125       assert(I->second.getNode()->isGlobalNode() && "Should be a global node!");
02126       GlobalNodes.push_back(std::make_pair(I->first, I->second.getNode()));
02127 
02128       // Make sure that all globals are cloned over as roots.
02129       if (!(Flags & DSGraph::RemoveUnreachableGlobals) && GlobalsGraph) {
02130         DSGraph::ScalarMapTy::iterator SMI =
02131           GlobalsGraph->getScalarMap().find(I->first);
02132         if (SMI != GlobalsGraph->getScalarMap().end())
02133           GGCloner.merge(SMI->second, I->second);
02134         else
02135           GGCloner.getClonedNH(I->second);
02136       }
02137     } else {
02138       I->second.getNode()->markReachableNodes(Alive);
02139     }
02140 }
02141 
02142   // The return values are alive as well.
02143   for (ReturnNodesTy::iterator I = ReturnNodes.begin(), E = ReturnNodes.end();
02144        I != E; ++I)
02145     I->second.getNode()->markReachableNodes(Alive);
02146 
02147   // Mark any nodes reachable by primary calls as alive...
02148   for (fc_iterator I = fc_begin(), E = fc_end(); I != E; ++I)
02149     I->markReachableNodes(Alive);
02150 
02151 
02152   // Now find globals and aux call nodes that are already live or reach a live
02153   // value (which makes them live in turn), and continue till no more are found.
02154   //
02155   bool Iterate;
02156   hash_set<const DSNode*> Visited;
02157   hash_set<const DSCallSite*> AuxFCallsAlive;
02158   do {
02159     Visited.clear();
02160     // If any global node points to a non-global that is "alive", the global is
02161     // "alive" as well...  Remove it from the GlobalNodes list so we only have
02162     // unreachable globals in the list.
02163     //
02164     Iterate = false;
02165     if (!(Flags & DSGraph::RemoveUnreachableGlobals))
02166       for (unsigned i = 0; i != GlobalNodes.size(); ++i)
02167         if (CanReachAliveNodes(GlobalNodes[i].second, Alive, Visited,
02168                                Flags & DSGraph::RemoveUnreachableGlobals)) {
02169           std::swap(GlobalNodes[i--], GlobalNodes.back()); // Move to end to...
02170           GlobalNodes.pop_back();                          // erase efficiently
02171           Iterate = true;
02172         }
02173 
02174     // Mark only unresolvable call nodes for moving to the GlobalsGraph since
02175     // call nodes that get resolved will be difficult to remove from that graph.
02176     // The final unresolved call nodes must be handled specially at the end of
02177     // the BU pass (i.e., in main or other roots of the call graph).
02178     for (afc_iterator CI = afc_begin(), E = afc_end(); CI != E; ++CI)
02179       if (!AuxFCallsAlive.count(&*CI) &&
02180           (CI->isIndirectCall()
02181            || CallSiteUsesAliveArgs(*CI, Alive, Visited,
02182                                   Flags & DSGraph::RemoveUnreachableGlobals))) {
02183         CI->markReachableNodes(Alive);
02184         AuxFCallsAlive.insert(&*CI);
02185         Iterate = true;
02186       }
02187   } while (Iterate);
02188 
02189   // Move dead aux function calls to the end of the list
02190   unsigned CurIdx = 0;
02191   for (std::list<DSCallSite>::iterator CI = AuxFunctionCalls.begin(),
02192          E = AuxFunctionCalls.end(); CI != E; )
02193     if (AuxFCallsAlive.count(&*CI))
02194       ++CI;
02195     else {
02196       // Copy and merge global nodes and dead aux call nodes into the
02197       // GlobalsGraph, and all nodes reachable from those nodes.  Update their
02198       // target pointers using the GGCloner.
02199       //
02200       if (!(Flags & DSGraph::RemoveUnreachableGlobals))
02201         GlobalsGraph->AuxFunctionCalls.push_back(DSCallSite(*CI, GGCloner));
02202 
02203       AuxFunctionCalls.erase(CI++);
02204     }
02205 
02206   // We are finally done with the GGCloner so we can destroy it.
02207   GGCloner.destroy();
02208 
02209   // At this point, any nodes which are visited, but not alive, are nodes
02210   // which can be removed.  Loop over all nodes, eliminating completely
02211   // unreachable nodes.
02212   //
02213   std::vector<DSNode*> DeadNodes;
02214   DeadNodes.reserve(Nodes.size());
02215   for (NodeListTy::iterator NI = Nodes.begin(), E = Nodes.end(); NI != E;) {
02216     DSNode *N = NI++;
02217     assert(!N->isForwarding() && "Forwarded node in nodes list?");
02218 
02219     if (!Alive.count(N)) {
02220       Nodes.remove(N);
02221       assert(!N->isForwarding() && "Cannot remove a forwarding node!");
02222       DeadNodes.push_back(N);
02223       N->dropAllReferences();
02224       ++NumDNE;
02225     }
02226   }
02227 
02228   // Remove all unreachable globals from the ScalarMap.
02229   // If flag RemoveUnreachableGlobals is set, GlobalNodes has only dead nodes.
02230   // In either case, the dead nodes will not be in the set Alive.
02231   for (unsigned i = 0, e = GlobalNodes.size(); i != e; ++i)
02232     if (!Alive.count(GlobalNodes[i].second))
02233       ScalarMap.erase(GlobalNodes[i].first);
02234     else
02235       assert((Flags & DSGraph::RemoveUnreachableGlobals) && "non-dead global");
02236 
02237   // Delete all dead nodes now since their referrer counts are zero.
02238   for (unsigned i = 0, e = DeadNodes.size(); i != e; ++i)
02239     delete DeadNodes[i];
02240 
02241   DEBUG(AssertGraphOK(); GlobalsGraph->AssertGraphOK());
02242 }
02243 
02244 void DSGraph::AssertNodeContainsGlobal(const DSNode *N, GlobalValue *GV) const {
02245   assert(std::find(N->globals_begin(),N->globals_end(), GV) !=
02246          N->globals_end() && "Global value not in node!");
02247 }
02248 
02249 void DSGraph::AssertCallSiteInGraph(const DSCallSite &CS) const {
02250   if (CS.isIndirectCall()) {
02251     AssertNodeInGraph(CS.getCalleeNode());
02252 #if 0
02253     if (CS.getNumPtrArgs() && CS.getCalleeNode() == CS.getPtrArg(0).getNode() &&
02254         CS.getCalleeNode() && CS.getCalleeNode()->getGlobals().empty())
02255       std::cerr << "WARNING: WEIRD CALL SITE FOUND!\n";
02256 #endif
02257   }
02258   AssertNodeInGraph(CS.getRetVal().getNode());
02259   for (unsigned j = 0, e = CS.getNumPtrArgs(); j != e; ++j)
02260     AssertNodeInGraph(CS.getPtrArg(j).getNode());
02261 }
02262 
02263 void DSGraph::AssertCallNodesInGraph() const {
02264   for (fc_iterator I = fc_begin(), E = fc_end(); I != E; ++I)
02265     AssertCallSiteInGraph(*I);
02266 }
02267 void DSGraph::AssertAuxCallNodesInGraph() const {
02268   for (afc_iterator I = afc_begin(), E = afc_end(); I != E; ++I)
02269     AssertCallSiteInGraph(*I);
02270 }
02271 
02272 void DSGraph::AssertGraphOK() const {
02273   for (node_const_iterator NI = node_begin(), E = node_end(); NI != E; ++NI)
02274     NI->assertOK();
02275 
02276   for (ScalarMapTy::const_iterator I = ScalarMap.begin(),
02277          E = ScalarMap.end(); I != E; ++I) {
02278     assert(!I->second.isNull() && "Null node in scalarmap!");
02279     AssertNodeInGraph(I->second.getNode());
02280     if (GlobalValue *GV = dyn_cast<GlobalValue>(I->first)) {
02281       assert(I->second.getNode()->isGlobalNode() &&
02282              "Global points to node, but node isn't global?");
02283       AssertNodeContainsGlobal(I->second.getNode(), GV);
02284     }
02285   }
02286   AssertCallNodesInGraph();
02287   AssertAuxCallNodesInGraph();
02288 
02289   // Check that all pointer arguments to any functions in this graph have
02290   // destinations.
02291   for (ReturnNodesTy::const_iterator RI = ReturnNodes.begin(),
02292          E = ReturnNodes.end();
02293        RI != E; ++RI) {
02294     Function &F = *RI->first;
02295     for (Function::arg_iterator AI = F.arg_begin(); AI != F.arg_end(); ++AI)
02296       if (isPointerType(AI->getType()))
02297         assert(!getNodeForValue(AI).isNull() &&
02298                "Pointer argument must be in the scalar map!");
02299   }
02300 }
02301 
02302 /// computeNodeMapping - Given roots in two different DSGraphs, traverse the
02303 /// nodes reachable from the two graphs, computing the mapping of nodes from the
02304 /// first to the second graph.  This mapping may be many-to-one (i.e. the first
02305 /// graph may have multiple nodes representing one node in the second graph),
02306 /// but it will not work if there is a one-to-many or many-to-many mapping.
02307 ///
02308 void DSGraph::computeNodeMapping(const DSNodeHandle &NH1,
02309                                  const DSNodeHandle &NH2, NodeMapTy &NodeMap,
02310                                  bool StrictChecking) {
02311   DSNode *N1 = NH1.getNode(), *N2 = NH2.getNode();
02312   if (N1 == 0 || N2 == 0) return;
02313 
02314   DSNodeHandle &Entry = NodeMap[N1];
02315   if (!Entry.isNull()) {
02316     // Termination of recursion!
02317     if (StrictChecking) {
02318       assert(Entry.getNode() == N2 && "Inconsistent mapping detected!");
02319       assert((Entry.getOffset() == (NH2.getOffset()-NH1.getOffset()) ||
02320               Entry.getNode()->isNodeCompletelyFolded()) &&
02321              "Inconsistent mapping detected!");
02322     }
02323     return;
02324   }
02325 
02326   Entry.setTo(N2, NH2.getOffset()-NH1.getOffset());
02327 
02328   // Loop over all of the fields that N1 and N2 have in common, recursively
02329   // mapping the edges together now.
02330   int N2Idx = NH2.getOffset()-NH1.getOffset();
02331   unsigned N2Size = N2->getSize();
02332   if (N2Size == 0) return;   // No edges to map to.
02333 
02334   for (unsigned i = 0, e = N1->getSize(); i < e; i += DS::PointerSize) {
02335     const DSNodeHandle &N1NH = N1->getLink(i);
02336     // Don't call N2->getLink if not needed (avoiding crash if N2Idx is not
02337     // aligned right).
02338     if (!N1NH.isNull()) {
02339       if (unsigned(N2Idx)+i < N2Size)
02340         computeNodeMapping(N1NH, N2->getLink(N2Idx+i), NodeMap);
02341       else
02342         computeNodeMapping(N1NH,
02343                            N2->getLink(unsigned(N2Idx+i) % N2Size), NodeMap);
02344     }
02345   }
02346 }
02347 
02348 
02349 /// computeGToGGMapping - Compute the mapping of nodes in the global graph to
02350 /// nodes in this graph.
02351 void DSGraph::computeGToGGMapping(NodeMapTy &NodeMap) {
02352   DSGraph &GG = *getGlobalsGraph();
02353 
02354   DSScalarMap &SM = getScalarMap();
02355   for (DSScalarMap::global_iterator I = SM.global_begin(),
02356          E = SM.global_end(); I != E; ++I)
02357     DSGraph::computeNodeMapping(SM[*I], GG.getNodeForValue(*I), NodeMap);
02358 }
02359 
02360 /// computeGGToGMapping - Compute the mapping of nodes in the global graph to
02361 /// nodes in this graph.  Note that any uses of this method are probably bugs,
02362 /// unless it is known that the globals graph has been merged into this graph!
02363 void DSGraph::computeGGToGMapping(InvNodeMapTy &InvNodeMap) {
02364   NodeMapTy NodeMap;
02365   computeGToGGMapping(NodeMap);
02366 
02367   while (!NodeMap.empty()) {
02368     InvNodeMap.insert(std::make_pair(NodeMap.begin()->second,
02369                                      NodeMap.begin()->first));
02370     NodeMap.erase(NodeMap.begin());
02371   }
02372 }
02373 
02374 
02375 /// computeCalleeCallerMapping - Given a call from a function in the current
02376 /// graph to the 'Callee' function (which lives in 'CalleeGraph'), compute the
02377 /// mapping of nodes from the callee to nodes in the caller.
02378 void DSGraph::computeCalleeCallerMapping(DSCallSite CS, const Function &Callee,
02379                                          DSGraph &CalleeGraph,
02380                                          NodeMapTy &NodeMap) {
02381 
02382   DSCallSite CalleeArgs =
02383     CalleeGraph.getCallSiteForArguments(const_cast<Function&>(Callee));
02384 
02385   computeNodeMapping(CalleeArgs.getRetVal(), CS.getRetVal(), NodeMap);
02386 
02387   unsigned NumArgs = CS.getNumPtrArgs();
02388   if (NumArgs > CalleeArgs.getNumPtrArgs())
02389     NumArgs = CalleeArgs.getNumPtrArgs();
02390 
02391   for (unsigned i = 0; i != NumArgs; ++i)
02392     computeNodeMapping(CalleeArgs.getPtrArg(i), CS.getPtrArg(i), NodeMap);
02393 
02394   // Map the nodes that are pointed to by globals.
02395   DSScalarMap &CalleeSM = CalleeGraph.getScalarMap();
02396   DSScalarMap &CallerSM = getScalarMap();
02397 
02398   if (CalleeSM.global_size() >= CallerSM.global_size()) {
02399     for (DSScalarMap::global_iterator GI = CallerSM.global_begin(),
02400            E = CallerSM.global_end(); GI != E; ++GI)
02401       if (CalleeSM.global_count(*GI))
02402         computeNodeMapping(CalleeSM[*GI], CallerSM[*GI], NodeMap);
02403   } else {
02404     for (DSScalarMap::global_iterator GI = CalleeSM.global_begin(),
02405            E = CalleeSM.global_end(); GI != E; ++GI)
02406       if (CallerSM.global_count(*GI))
02407         computeNodeMapping(CalleeSM[*GI], CallerSM[*GI], NodeMap);
02408   }
02409 }
02410 
02411 /// updateFromGlobalGraph - This function rematerializes global nodes and
02412 /// nodes reachable from them from the globals graph into the current graph.
02413 ///
02414 void DSGraph::updateFromGlobalGraph() {
02415   TIME_REGION(X, "updateFromGlobalGraph");
02416   ReachabilityCloner RC(*this, *GlobalsGraph, 0);
02417 
02418   // Clone the non-up-to-date global nodes into this graph.
02419   for (DSScalarMap::global_iterator I = getScalarMap().global_begin(),
02420          E = getScalarMap().global_end(); I != E; ++I) {
02421     DSScalarMap::iterator It = GlobalsGraph->ScalarMap.find(*I);
02422     if (It != GlobalsGraph->ScalarMap.end())
02423       RC.merge(getNodeForValue(*I), It->second);
02424   }
02425 }