293 lines
12 KiB
C++
293 lines
12 KiB
C++
//===- TopDownClosure.cpp - Compute the top-down interprocedure closure ---===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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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/DataStructure.h"
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#include "llvm/Module.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Analysis/DataStructure/DSGraph.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/ADT/Statistic.h"
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using namespace llvm;
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namespace {
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RegisterAnalysis<TDDataStructures> // Register the pass
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Y("tddatastructure", "Top-down Data Structure Analysis");
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Statistic<> NumTDInlines("tddatastructures", "Number of graphs inlined");
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}
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void TDDataStructures::markReachableFunctionsExternallyAccessible(DSNode *N,
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hash_set<DSNode*> &Visited) {
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if (!N || Visited.count(N)) return;
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Visited.insert(N);
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for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i) {
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DSNodeHandle &NH = N->getLink(i*N->getPointerSize());
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if (DSNode *NN = NH.getNode()) {
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const std::vector<GlobalValue*> &Globals = NN->getGlobals();
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for (unsigned G = 0, e = Globals.size(); G != e; ++G)
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if (Function *F = dyn_cast<Function>(Globals[G]))
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ArgsRemainIncomplete.insert(F);
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markReachableFunctionsExternallyAccessible(NN, Visited);
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}
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}
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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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BUDataStructures &BU = getAnalysis<BUDataStructures>();
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GlobalsGraph = new DSGraph(BU.getGlobalsGraph());
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GlobalsGraph->setPrintAuxCalls();
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// Figure out which functions must not mark their arguments complete because
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// they are accessible outside this compilation unit. Currently, these
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// arguments are functions which are reachable by global variables in the
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// globals graph.
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const DSScalarMap &GGSM = GlobalsGraph->getScalarMap();
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hash_set<DSNode*> Visited;
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for (DSScalarMap::global_iterator I=GGSM.global_begin(), E=GGSM.global_end();
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I != E; ++I)
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markReachableFunctionsExternallyAccessible(GGSM.find(*I)->second.getNode(),
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Visited);
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// Loop over unresolved call nodes. Any functions passed into (but not
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// returned!) from unresolvable call nodes may be invoked outside of the
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// current module.
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const std::vector<DSCallSite> &Calls = GlobalsGraph->getAuxFunctionCalls();
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for (unsigned i = 0, e = Calls.size(); i != e; ++i) {
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const DSCallSite &CS = Calls[i];
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for (unsigned arg = 0, e = CS.getNumPtrArgs(); arg != e; ++arg)
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markReachableFunctionsExternallyAccessible(CS.getPtrArg(arg).getNode(),
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Visited);
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}
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Visited.clear();
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// Functions without internal linkage also have unknown incoming arguments!
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for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
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if (!I->isExternal() && !I->hasInternalLinkage())
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ArgsRemainIncomplete.insert(I);
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// We want to traverse the call graph in reverse post-order. To do this, we
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// calculate a post-order traversal, then reverse it.
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hash_set<DSGraph*> VisitedGraph;
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std::vector<DSGraph*> PostOrder;
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const BUDataStructures::ActualCalleesTy &ActualCallees =
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getAnalysis<BUDataStructures>().getActualCallees();
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// Calculate top-down from main...
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if (Function *F = M.getMainFunction())
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ComputePostOrder(*F, VisitedGraph, PostOrder, ActualCallees);
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// Next calculate the graphs for each unreachable function...
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for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
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ComputePostOrder(*I, VisitedGraph, PostOrder, ActualCallees);
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VisitedGraph.clear(); // Release memory!
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// Visit each of the graphs in reverse post-order now!
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while (!PostOrder.empty()) {
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inlineGraphIntoCallees(*PostOrder.back());
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PostOrder.pop_back();
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}
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ArgsRemainIncomplete.clear();
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GlobalsGraph->removeTriviallyDeadNodes();
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return false;
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}
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DSGraph &TDDataStructures::getOrCreateDSGraph(Function &F) {
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DSGraph *&G = DSInfo[&F];
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if (G == 0) { // Not created yet? Clone BU graph...
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G = new DSGraph(getAnalysis<BUDataStructures>().getDSGraph(F));
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G->getAuxFunctionCalls().clear();
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G->setPrintAuxCalls();
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G->setGlobalsGraph(GlobalsGraph);
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}
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return *G;
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}
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void TDDataStructures::ComputePostOrder(Function &F,hash_set<DSGraph*> &Visited,
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std::vector<DSGraph*> &PostOrder,
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const BUDataStructures::ActualCalleesTy &ActualCallees) {
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if (F.isExternal()) return;
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DSGraph &G = getOrCreateDSGraph(F);
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if (Visited.count(&G)) return;
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Visited.insert(&G);
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// Recursively traverse all of the callee graphs.
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const std::vector<DSCallSite> &FunctionCalls = G.getFunctionCalls();
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for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i) {
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Instruction *CallI = FunctionCalls[i].getCallSite().getInstruction();
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std::pair<BUDataStructures::ActualCalleesTy::const_iterator,
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BUDataStructures::ActualCalleesTy::const_iterator>
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IP = ActualCallees.equal_range(CallI);
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for (BUDataStructures::ActualCalleesTy::const_iterator I = IP.first;
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I != IP.second; ++I)
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ComputePostOrder(*I->second, Visited, PostOrder, ActualCallees);
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}
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PostOrder.push_back(&G);
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}
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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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// FIXME: This should be releaseMemory and will work fine, except that LoadVN
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// has no way to extend the lifetime of the pass, which screws up ds-aa.
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//
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void TDDataStructures::releaseMyMemory() {
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for (hash_map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
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E = DSInfo.end(); I != E; ++I) {
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I->second->getReturnNodes().erase(I->first);
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if (I->second->getReturnNodes().empty())
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delete I->second;
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}
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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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delete GlobalsGraph;
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GlobalsGraph = 0;
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}
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void TDDataStructures::inlineGraphIntoCallees(DSGraph &Graph) {
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// Recompute the Incomplete markers and eliminate unreachable nodes.
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Graph.maskIncompleteMarkers();
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// If any of the functions has incomplete incoming arguments, don't mark any
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// of them as complete.
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bool HasIncompleteArgs = false;
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const DSGraph::ReturnNodesTy &GraphReturnNodes = Graph.getReturnNodes();
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for (DSGraph::ReturnNodesTy::const_iterator I = GraphReturnNodes.begin(),
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E = GraphReturnNodes.end(); I != E; ++I)
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if (ArgsRemainIncomplete.count(I->first)) {
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HasIncompleteArgs = true;
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break;
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}
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// Now fold in the necessary globals from the GlobalsGraph. A global G
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// must be folded in if it exists in the current graph (i.e., is not dead)
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// and it was not inlined from any of my callers. If it was inlined from
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// a caller, it would have been fully consistent with the GlobalsGraph
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// in the caller so folding in is not necessary. Otherwise, this node came
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// solely from this function's BU graph and so has to be made consistent.
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//
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Graph.updateFromGlobalGraph();
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// Recompute the Incomplete markers. Depends on whether args are complete
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unsigned Flags
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= HasIncompleteArgs ? DSGraph::MarkFormalArgs : DSGraph::IgnoreFormalArgs;
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Graph.markIncompleteNodes(Flags | DSGraph::IgnoreGlobals);
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// Delete dead nodes. Treat globals that are unreachable as dead also.
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Graph.removeDeadNodes(DSGraph::RemoveUnreachableGlobals);
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// We are done with computing the current TD Graph! Now move on to
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// inlining the current graph into the graphs for its callees, if any.
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//
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const std::vector<DSCallSite> &FunctionCalls = Graph.getFunctionCalls();
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if (FunctionCalls.empty()) {
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DEBUG(std::cerr << " [TD] No callees for: " << Graph.getFunctionNames()
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<< "\n");
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return;
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}
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// Now that we have information about all of the callees, propagate the
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// current graph into the callees. Clone only the reachable subgraph at
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// each call-site, not the entire graph (even though the entire graph
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// would be cloned only once, this should still be better on average).
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//
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DEBUG(std::cerr << " [TD] Inlining '" << Graph.getFunctionNames() <<"' into "
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<< FunctionCalls.size() << " call nodes.\n");
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const BUDataStructures::ActualCalleesTy &ActualCallees =
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getAnalysis<BUDataStructures>().getActualCallees();
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// Loop over all the call sites and all the callees at each call site. Build
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// a mapping from called DSGraph's to the call sites in this function that
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// invoke them. This is useful because we can be more efficient if there are
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// multiple call sites to the callees in the graph from this caller.
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std::multimap<DSGraph*, std::pair<Function*, const DSCallSite*> > CallSites;
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for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i) {
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Instruction *CallI = FunctionCalls[i].getCallSite().getInstruction();
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// For each function in the invoked function list at this call site...
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std::pair<BUDataStructures::ActualCalleesTy::const_iterator,
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BUDataStructures::ActualCalleesTy::const_iterator>
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IP = ActualCallees.equal_range(CallI);
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// Loop over each actual callee at this call site
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for (BUDataStructures::ActualCalleesTy::const_iterator I = IP.first;
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I != IP.second; ++I) {
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DSGraph& CalleeGraph = getDSGraph(*I->second);
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assert(&CalleeGraph != &Graph && "TD need not inline graph into self!");
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CallSites.insert(std::make_pair(&CalleeGraph,
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std::make_pair(I->second, &FunctionCalls[i])));
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}
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}
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// Now that we built the mapping, actually perform the inlining a callee graph
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// at a time.
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std::multimap<DSGraph*,std::pair<Function*,const DSCallSite*> >::iterator CSI;
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for (CSI = CallSites.begin(); CSI != CallSites.end(); ) {
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DSGraph &CalleeGraph = *CSI->first;
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// Iterate through all of the call sites of this graph, cloning and merging
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// any nodes required by the call.
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ReachabilityCloner RC(CalleeGraph, Graph, DSGraph::StripModRefBits);
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// Clone over any global nodes that appear in both graphs.
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for (DSScalarMap::global_iterator
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SI = CalleeGraph.getScalarMap().global_begin(),
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SE = CalleeGraph.getScalarMap().global_end(); SI != SE; ++SI) {
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DSScalarMap::const_iterator GI = Graph.getScalarMap().find(*SI);
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if (GI != Graph.getScalarMap().end())
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RC.merge(CalleeGraph.getNodeForValue(*SI), GI->second);
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}
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// Loop over all of the distinct call sites in the caller of the callee.
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for (; CSI != CallSites.end() && CSI->first == &CalleeGraph; ++CSI) {
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Function &CF = *CSI->second.first;
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const DSCallSite &CS = *CSI->second.second;
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DEBUG(std::cerr << " [TD] Resolving arguments for callee graph '"
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<< CalleeGraph.getFunctionNames()
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<< "': " << CF.getFunctionType()->getNumParams()
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<< " args\n at call site (DSCallSite*) 0x" << &CS << "\n");
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// Get the formal argument and return nodes for the called function and
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// merge them with the cloned subgraph.
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RC.mergeCallSite(CalleeGraph.getCallSiteForArguments(CF), CS);
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++NumTDInlines;
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}
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}
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DEBUG(std::cerr << " [TD] Done inlining into callees for: "
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<< Graph.getFunctionNames() << " [" << Graph.getGraphSize() << "+"
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<< Graph.getFunctionCalls().size() << "]\n");
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}
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