forked from OSchip/llvm-project
This file implements the top-down propagation pass for data structure graphs.
Also, we now use a separate globals graph to hold externally visible nodes. This changes both the bottom-up and top-down propagation so that globals and other external objects do not have to appear in every function, but only in functions in which they are referenced or they can be used to access something else that is referenced. llvm-svn: 3171
This commit is contained in:
Vikram S. Adve
parent
0d66177bc8
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90c8892b4e
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//===- TopDownClosure.cpp - Compute the top-down interprocedure closure ---===//
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//
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// This file implements the TDDataStructures class, which represents the
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// Top-down Interprocedural closure of the data structure graph over the
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// program. This is useful (but not strictly necessary?) for applications
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// like pointer analysis.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/DataStructure.h"
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#include "llvm/Module.h"
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#include "llvm/DerivedTypes.h"
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#include "Support/StatisticReporter.h"
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using std::map;
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static RegisterAnalysis<TDDataStructures>
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Y("tddatastructure", "Top-down Data Structure Analysis Closure");
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AnalysisID TDDataStructures::ID = Y;
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// releaseMemory - If the pass pipeline is done with this pass, we can release
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// our memory... here...
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//
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void TDDataStructures::releaseMemory() {
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for (map<const Function*, DSGraph*>::iterator I = DSInfo.begin(),
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E = DSInfo.end(); I != E; ++I)
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delete I->second;
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// Empty map so next time memory is released, data structures are not
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// re-deleted.
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DSInfo.clear();
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}
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// run - Calculate the top down data structure graphs for each function in the
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// program.
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//
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bool TDDataStructures::run(Module &M) {
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// Simply calculate the graphs for each function...
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for (Module::reverse_iterator I = M.rbegin(), E = M.rend(); I != E; ++I)
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if (!I->isExternal())
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calculateGraph(*I);
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return false;
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}
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// ResolveArguments - Resolve the formal and actual arguments for a function
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// call by merging the nodes for the actual arguments at the call site Call[]
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// (these were copied over from the caller's graph into the callee's graph
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// by cloneInto, and the nodes can be found from OldNodeMap) with the
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// corresponding nodes for the formal arguments in the callee.
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//
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static void ResolveArguments(std::vector<DSNodeHandle> &Call,
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Function &callee,
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std::map<Value*, DSNodeHandle> &CalleeValueMap,
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std::map<const DSNode*, DSNode*> OldNodeMap,
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bool ignoreNodeMap) {
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// Resolve all of the function formal arguments...
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Function::aiterator AI = callee.abegin();
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for (unsigned i = 2, e = Call.size(); i != e; ++i) {
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// Advance the argument iterator to the first pointer argument...
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while (!isa<PointerType>(AI->getType())) ++AI;
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// TD ...Merge the formal arg scalar with the actual arg node
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DSNode* actualArg = Call[i];
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DSNode *nodeForActual = ignoreNodeMap? actualArg : OldNodeMap[actualArg];
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assert(nodeForActual && "No node found for actual arg in callee graph!");
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DSNode *nodeForFormal = CalleeValueMap[AI]->getLink(0);
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if (nodeForFormal)
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nodeForFormal->mergeWith(nodeForActual);
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++AI;
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}
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}
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// MergeGlobalNodes - Merge all existing global nodes with globals
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// inlined from the callee or with globals from the GlobalsGraph.
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//
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static void MergeGlobalNodes(DSGraph& Graph,
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map<Value*, DSNodeHandle> &OldValMap) {
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map<Value*, DSNodeHandle> &ValMap = Graph.getValueMap();
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for (map<Value*, DSNodeHandle>::iterator I = ValMap.begin(), E = ValMap.end();
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I != E; ++I)
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if (GlobalValue* GV = dyn_cast<GlobalValue>(I->first)) {
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map<Value*, DSNodeHandle>:: iterator NHI = OldValMap.find(GV);
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if (NHI != OldValMap.end()) // was it inlined from the callee?
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I->second->mergeWith(NHI->second);
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else // get it from the GlobalsGraph
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I->second->mergeWith(Graph.cloneGlobalInto(GV));
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}
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// Add unused inlined global nodes into the value map
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for (map<Value*, DSNodeHandle>::iterator I = OldValMap.begin(),
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E = OldValMap.end(); I != E; ++I)
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if (isa<GlobalValue>(I->first)) {
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DSNodeHandle &NH = ValMap[I->first]; // If global is not in ValMap...
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if (NH == 0)
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NH = I->second; // Add the one just inlined.
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}
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}
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// Helper function to push a caller's graph into the calleeGraph,
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// once per call between the caller and the callee.
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// Remove each such resolved call from the OrigFunctionCalls vector.
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// NOTE: This may produce O(N^2) behavior because it uses linear search
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// through the vector OrigFunctionCalls to find all calls to this callee.
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//
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void TDDataStructures::pushGraphIntoCallee(DSGraph &callerGraph,
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DSGraph &calleeGraph,
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std::map<Value*, DSNodeHandle> &OldValMap,
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std::map<const DSNode*, DSNode*> &OldNodeMap) {
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Function& caller = callerGraph.getFunction();
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// Loop over all function calls in the caller to find those to this callee
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std::vector<std::vector<DSNodeHandle> >& FunctionCalls =
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callerGraph.getOrigFunctionCalls();
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for (unsigned i = 0, ei = FunctionCalls.size(); i != ei; ++i) {
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std::vector<DSNodeHandle>& Call = FunctionCalls[i];
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assert(Call.size() >= 2 && "No function pointer in Call?");
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DSNodeHandle& callee = Call[1];
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std::vector<GlobalValue*> funcPtrs(callee->getGlobals());
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// Loop over the function pointers in the call, looking for the callee
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for (unsigned f = 0; f != funcPtrs.size(); ++f) {
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// Must be a function type, so this cast MUST succeed.
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Function &callee = cast<Function>(*funcPtrs[f]);
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if (&callee != &calleeGraph.getFunction())
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continue;
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// Found a call to the callee. Inline its graph
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// copy caller pointer because inlining may modify the callers vector
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// Merge actual arguments from the caller with formals in the callee.
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// Don't use the old->new node map if this is a self-recursive call.
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ResolveArguments(Call, callee, calleeGraph.getValueMap(), OldNodeMap,
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/*ignoreNodeMap*/ &caller == &callee);
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// If its not a self-recursive call, merge global nodes in the inlined
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// graph with the corresponding global nodes in the current graph
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if (&caller != &callee)
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MergeGlobalNodes(calleeGraph, OldValMap);
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// Merge returned node in the caller with the "return" node in callee
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if (Call[0])
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calleeGraph.getRetNode()->mergeWith(OldNodeMap[Call[0]]);
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// Erase the entry in the globals vector
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funcPtrs.erase(funcPtrs.begin()+f--);
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} // for each function pointer in the call node
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} // for each original call node
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}
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DSGraph &TDDataStructures::calculateGraph(Function &F) {
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// Make sure this graph has not already been calculated, or that we don't get
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// into an infinite loop with mutually recursive functions.
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//
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DSGraph *&Graph = DSInfo[&F];
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if (Graph) return *Graph;
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// Copy the local version into DSInfo...
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DSGraph& BUGraph = getAnalysis<BUDataStructures>().getDSGraph(F);
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Graph = new DSGraph(BUGraph);
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// Find the callers of this function recorded during the BU pass
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std::set<Function*> &PendingCallers = BUGraph.getPendingCallers();
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DEBUG(cerr << " [TD] Inlining callers for: " << F.getName() << "\n");
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for (std::set<Function*>::iterator I=PendingCallers.begin(),
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E=PendingCallers.end(); I != E; ++I) {
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Function& caller = **I;
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assert(! caller.isExternal() && "Externals unexpected in callers list");
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DEBUG(std::cerr << "\t [TD] Inlining " << caller.getName()
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<< " into callee: " << F.getName() << "\n");
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// These two maps keep track of where scalars in the old graph _used_
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// to point to, and of new nodes matching nodes of the old graph.
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// These remain empty if no other graph is inlined (i.e., self-recursive).
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std::map<const DSNode*, DSNode*> OldNodeMap;
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std::map<Value*, DSNodeHandle> OldValMap;
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if (&caller == &F) {
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// Self-recursive call: this can happen after a cycle of calls is inlined.
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pushGraphIntoCallee(*Graph, *Graph, OldValMap, OldNodeMap);
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}
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else {
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// Recursively compute the graph for the caller. That should
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// be fully resolved except if there is mutual recursion...
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//
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DSGraph &callerGraph = calculateGraph(caller); // Graph to inline
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DEBUG(cerr << "\t\t[TD] Got graph for " << caller.getName() << " in: "
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<< F.getName() << "\n");
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// Clone the caller's graph into the current graph, keeping
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// track of where scalars in the old graph _used_ to point...
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// Do this here because it only needs to happens once for each caller!
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// Strip scalars but not allocas since they are visible in callee.
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//
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DSNode *RetVal = Graph->cloneInto(callerGraph, OldValMap, OldNodeMap,
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/*StripScalars*/ true,
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/*StripAllocas*/ false,
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/*CopyCallers*/ true,
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/*CopyOrigCalls*/ false);
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pushGraphIntoCallee(callerGraph, *Graph, OldValMap, OldNodeMap);
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}
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}
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// Recompute the Incomplete markers and eliminate unreachable nodes.
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Graph->maskIncompleteMarkers();
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Graph->markIncompleteNodes(/*markFormals*/ ! F.hasInternalLinkage()
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/*&& FIXME: NEED TO CHECK IF ALL CALLERS FOUND!*/);
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Graph->removeDeadNodes(/*KeepAllGlobals*/ false, /*KeepCalls*/ false);
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DEBUG(cerr << " [TD] Done inlining callers for: " << F.getName() << "\n");
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return *Graph;
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}
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