//===- DataStructure.cpp - Implement the core data structure analysis -----===// // // This file implements the core data structure functionality. // //===----------------------------------------------------------------------===// #include "llvm/Module.h" #include "llvm/DerivedTypes.h" #include "Support/STLExtras.h" #include "Support/StatisticReporter.h" #include "Support/STLExtras.h" #include #include #include "llvm/Analysis/DataStructure.h" using std::vector; //===----------------------------------------------------------------------===// // DSNode Implementation //===----------------------------------------------------------------------===// DSNode::DSNode(enum NodeTy NT, const Type *T) : Ty(T), NodeType(NT) { // If this node has any fields, allocate them now, but leave them null. switch (T->getPrimitiveID()) { case Type::PointerTyID: Links.resize(1); break; case Type::ArrayTyID: Links.resize(1); break; case Type::StructTyID: Links.resize(cast(T)->getNumContainedTypes()); break; default: break; } } // DSNode copy constructor... do not copy over the referrers list! DSNode::DSNode(const DSNode &N) : Ty(N.Ty), Links(N.Links), Globals(N.Globals), NodeType(N.NodeType) { } void DSNode::removeReferrer(DSNodeHandle *H) { // Search backwards, because we depopulate the list from the back for // efficiency (because it's a vector). vector::reverse_iterator I = std::find(Referrers.rbegin(), Referrers.rend(), H); assert(I != Referrers.rend() && "Referrer not pointing to node!"); Referrers.erase(I.base()-1); } // addGlobal - Add an entry for a global value to the Globals list. This also // marks the node with the 'G' flag if it does not already have it. // void DSNode::addGlobal(GlobalValue *GV) { // Keep the list sorted. vector::iterator I = std::lower_bound(Globals.begin(), Globals.end(), GV); if (I == Globals.end() || *I != GV) { assert(GV->getType()->getElementType() == Ty); Globals.insert(I, GV); NodeType |= GlobalNode; } } // addEdgeTo - Add an edge from the current node to the specified node. This // can cause merging of nodes in the graph. // void DSNode::addEdgeTo(unsigned LinkNo, DSNode *N) { assert(LinkNo < Links.size() && "LinkNo out of range!"); if (N == 0 || Links[LinkNo] == N) return; // Nothing to do if (Links[LinkNo] == 0) { // No merging to perform Links[LinkNo] = N; return; } // Merge the two nodes... Links[LinkNo]->mergeWith(N); } // mergeWith - Merge this node into the specified node, moving all links to and // from the argument node into the current node. The specified node may be a // null pointer (in which case, nothing happens). // void DSNode::mergeWith(DSNode *N) { if (N == 0 || N == this) return; // Noop assert(N->Ty == Ty && N->Links.size() == Links.size() && "Cannot merge nodes of two different types!"); // Remove all edges pointing at N, causing them to point to 'this' instead. while (!N->Referrers.empty()) *N->Referrers.back() = this; // Make all of the outgoing links of N now be outgoing links of this. This // can cause recursive merging! // for (unsigned i = 0, e = Links.size(); i != e; ++i) { addEdgeTo(i, N->Links[i]); N->Links[i] = 0; // Reduce unneccesary edges in graph. N is dead } // Merge the node types NodeType |= N->NodeType; N->NodeType = 0; // N is now a dead node. // Merge the globals list... if (!N->Globals.empty()) { // Save the current globals off to the side... vector OldGlobals(Globals); // Resize the globals vector to be big enough to hold both of them... Globals.resize(Globals.size()+N->Globals.size()); // Merge the two sorted globals lists together... std::merge(OldGlobals.begin(), OldGlobals.end(), N->Globals.begin(), N->Globals.end(), Globals.begin()); // Erase duplicate entries from the globals list... Globals.erase(std::unique(Globals.begin(), Globals.end()), Globals.end()); // Delete the globals from the old node... N->Globals.clear(); } } //===----------------------------------------------------------------------===// // DSGraph Implementation //===----------------------------------------------------------------------===// DSGraph::DSGraph(const DSGraph &G) : Func(G.Func) { std::map NodeMap; // ignored RetNode = cloneInto(G, ValueMap, NodeMap, false); } DSGraph::~DSGraph() { FunctionCalls.clear(); OrigFunctionCalls.clear(); ValueMap.clear(); RetNode = 0; #ifndef NDEBUG // Drop all intra-node references, so that assertions don't fail... std::for_each(Nodes.begin(), Nodes.end(), std::mem_fun(&DSNode::dropAllReferences)); #endif // Delete all of the nodes themselves... std::for_each(Nodes.begin(), Nodes.end(), deleter); } // dump - Allow inspection of graph in a debugger. void DSGraph::dump() const { print(std::cerr); } // cloneInto - Clone the specified DSGraph into the current graph, returning the // Return node of the graph. The translated ValueMap for the old function is // filled into the OldValMap member. If StripLocals is set to true, Scalar and // Alloca markers are removed from the graph, as the graph is being cloned into // a calling function's graph. // DSNode *DSGraph::cloneInto(const DSGraph &G, std::map &OldValMap, std::map &OldNodeMap, bool StripLocals) { assert(OldNodeMap.size()==0 && "Return argument OldNodeMap should be empty"); OldNodeMap[0] = 0; // Null pointer maps to null unsigned FN = Nodes.size(); // FirstNode... // Duplicate all of the nodes, populating the node map... Nodes.reserve(FN+G.Nodes.size()); for (unsigned i = 0, e = G.Nodes.size(); i != e; ++i) { DSNode *Old = G.Nodes[i], *New = new DSNode(*Old); Nodes.push_back(New); OldNodeMap[Old] = New; } // Rewrite the links in the nodes to point into the current graph now. for (unsigned i = FN, e = Nodes.size(); i != e; ++i) for (unsigned j = 0, e = Nodes[i]->getNumLinks(); j != e; ++j) Nodes[i]->setLink(j, OldNodeMap[Nodes[i]->getLink(j)]); // If we are inlining this graph into the called function graph, remove local // markers. if (StripLocals) for (unsigned i = FN, e = Nodes.size(); i != e; ++i) Nodes[i]->NodeType &= ~(DSNode::AllocaNode | DSNode::ScalarNode); // Copy the value map... for (std::map::const_iterator I = G.ValueMap.begin(), E = G.ValueMap.end(); I != E; ++I) OldValMap[I->first] = OldNodeMap[I->second]; // Copy the function calls list... unsigned FC = FunctionCalls.size(); // FirstCall FunctionCalls.reserve(FC+G.FunctionCalls.size()); for (unsigned i = 0, e = G.FunctionCalls.size(); i != e; ++i) { FunctionCalls.push_back(std::vector()); FunctionCalls[FC+i].reserve(G.FunctionCalls[i].size()); for (unsigned j = 0, e = G.FunctionCalls[i].size(); j != e; ++j) FunctionCalls[FC+i].push_back(OldNodeMap[G.FunctionCalls[i][j]]); } // Copy the list of unresolved callers PendingCallers.insert(PendingCallers.end(), G.PendingCallers.begin(), G.PendingCallers.end()); // Return the returned node pointer... return OldNodeMap[G.RetNode]; } // markIncompleteNodes - Mark the specified node as having contents that are not // known with the current analysis we have performed. Because a node makes all // of the nodes it can reach imcomplete if the node itself is incomplete, we // must recursively traverse the data structure graph, marking all reachable // nodes as incomplete. // static void markIncompleteNode(DSNode *N) { // Stop recursion if no node, or if node already marked... if (N == 0 || (N->NodeType & DSNode::Incomplete)) return; // Actually mark the node N->NodeType |= DSNode::Incomplete; // Recusively process children... for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i) markIncompleteNode(N->getLink(i)); } // markIncompleteNodes - Traverse the graph, identifying nodes that may be // modified by other functions that have not been resolved yet. This marks // nodes that are reachable through three sources of "unknownness": // // Global Variables, Function Calls, and Incoming Arguments // // For any node that may have unknown components (because something outside the // scope of current analysis may have modified it), the 'Incomplete' flag is // added to the NodeType. // void DSGraph::markIncompleteNodes() { // Mark any incoming arguments as incomplete... for (Function::aiterator I = Func.abegin(), E = Func.aend(); I != E; ++I) if (isa(I->getType())) markIncompleteNode(ValueMap[I]->getLink(0)); // Mark stuff passed into functions calls as being incomplete... for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i) { vector &Args = FunctionCalls[i]; // Then the return value is certainly incomplete! markIncompleteNode(Args[0]); // The call does not make the function argument incomplete... // All arguments to the function call are incomplete though! for (unsigned i = 2, e = Args.size(); i != e; ++i) markIncompleteNode(Args[i]); } // Mark all of the nodes pointed to by global or cast nodes as incomplete... for (unsigned i = 0, e = Nodes.size(); i != e; ++i) if (Nodes[i]->NodeType & (DSNode::GlobalNode | DSNode::CastNode)) { DSNode *N = Nodes[i]; for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i) markIncompleteNode(N->getLink(i)); } } // isNodeDead - This method checks to see if a node is dead, and if it isn't, it // checks to see if there are simple transformations that it can do to make it // dead. // bool DSGraph::isNodeDead(DSNode *N) { // Is it a trivially dead shadow node... if (N->getReferrers().empty() && N->NodeType == 0) return true; // Is it a function node or some other trivially unused global? if ((N->NodeType & ~DSNode::GlobalNode) == 0 && N->getNumLinks() == 0 && N->getReferrers().size() == N->getGlobals().size()) { // Remove the globals from the valuemap, so that the referrer count will go // down to zero. while (!N->getGlobals().empty()) { GlobalValue *GV = N->getGlobals().back(); N->getGlobals().pop_back(); ValueMap.erase(GV); } assert(N->getReferrers().empty() && "Referrers should all be gone now!"); return true; } return false; } // removeTriviallyDeadNodes - After the graph has been constructed, this method // removes all unreachable nodes that are created because they got merged with // other nodes in the graph. These nodes will all be trivially unreachable, so // we don't have to perform any non-trivial analysis here. // void DSGraph::removeTriviallyDeadNodes() { for (unsigned i = 0; i != Nodes.size(); ++i) if (isNodeDead(Nodes[i])) { // This node is dead! delete Nodes[i]; // Free memory... Nodes.erase(Nodes.begin()+i--); // Remove from node list... } // Remove trivially identical function calls unsigned NumFns = FunctionCalls.size(); std::sort(FunctionCalls.begin(), FunctionCalls.end()); FunctionCalls.erase(std::unique(FunctionCalls.begin(), FunctionCalls.end()), FunctionCalls.end()); DEBUG(if (NumFns != FunctionCalls.size()) std::cerr << "Merged " << (NumFns-FunctionCalls.size()) << " call nodes in " << Func.getName() << "\n";); } // markAlive - Simple graph traverser that recursively walks the graph marking // stuff to be alive. // static void markAlive(DSNode *N, std::set &Alive) { if (N == 0 || Alive.count(N)) return; Alive.insert(N); for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i) markAlive(N->getLink(i), Alive); } // removeDeadNodes - Use a more powerful reachability analysis to eliminate // subgraphs that are unreachable. This often occurs because the data // structure doesn't "escape" into it's caller, and thus should be eliminated // from the caller's graph entirely. This is only appropriate to use when // inlining graphs. // void DSGraph::removeDeadNodes() { // Reduce the amount of work we have to do... removeTriviallyDeadNodes(); // FIXME: Merge nontrivially identical call nodes... // Alive - a set that holds all nodes found to be reachable/alive. std::set Alive; // Mark all nodes reachable by call nodes as alive... for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i) for (unsigned j = 0, e = FunctionCalls[i].size(); j != e; ++j) markAlive(FunctionCalls[i][j], Alive); for (unsigned i = 0, e = OrigFunctionCalls.size(); i != e; ++i) for (unsigned j = 0, e = OrigFunctionCalls[i].size(); j != e; ++j) markAlive(OrigFunctionCalls[i][j], Alive); // Mark all nodes reachable by scalar, global, or incomplete nodes as // reachable... for (unsigned i = 0, e = Nodes.size(); i != e; ++i) if (Nodes[i]->NodeType & (DSNode::ScalarNode | DSNode::GlobalNode)) markAlive(Nodes[i], Alive); // Loop over all unreachable nodes, dropping their references... std::vector DeadNodes; DeadNodes.reserve(Nodes.size()); // Only one allocation is allowed. for (unsigned i = 0; i != Nodes.size(); ++i) if (!Alive.count(Nodes[i])) { DSNode *N = Nodes[i]; Nodes.erase(Nodes.begin()+i--); // Erase node from alive list. DeadNodes.push_back(N); // Add node to our list of dead nodes N->dropAllReferences(); // Drop all outgoing edges } // The return value is alive as well... markAlive(RetNode, Alive); // Delete all dead nodes... std::for_each(DeadNodes.begin(), DeadNodes.end(), deleter); } // maskNodeTypes - Apply a mask to all of the node types in the graph. This // is useful for clearing out markers like Scalar or Incomplete. // void DSGraph::maskNodeTypes(unsigned char Mask) { for (unsigned i = 0, e = Nodes.size(); i != e; ++i) Nodes[i]->NodeType &= Mask; } //===----------------------------------------------------------------------===// // LocalDataStructures Implementation //===----------------------------------------------------------------------===// // releaseMemory - If the pass pipeline is done with this pass, we can release // our memory... here... // void LocalDataStructures::releaseMemory() { for (std::map::iterator I = DSInfo.begin(), E = DSInfo.end(); I != E; ++I) delete I->second; // Empty map so next time memory is released, data structures are not // re-deleted. DSInfo.clear(); } bool LocalDataStructures::run(Module &M) { // Calculate all of the graphs... for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) if (!I->isExternal()) DSInfo.insert(std::make_pair(&*I, new DSGraph(*I))); return false; }