1 //===- TopDownClosure.cpp - Compute the top-down interprocedure closure ---===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the TDDataStructures class, which represents the
11 // Top-down Interprocedural closure of the data structure graph over the
12 // program. This is useful (but not strictly necessary?) for applications
13 // like pointer analysis.
15 //===----------------------------------------------------------------------===//
17 #include "llvm/Analysis/DataStructure.h"
18 #include "llvm/Module.h"
19 #include "llvm/DerivedTypes.h"
20 #include "llvm/Analysis/DSGraph.h"
21 #include "Support/Debug.h"
22 #include "Support/Statistic.h"
26 RegisterAnalysis<TDDataStructures> // Register the pass
27 Y("tddatastructure", "Top-down Data Structure Analysis");
29 Statistic<> NumTDInlines("tddatastructures", "Number of graphs inlined");
32 void TDDataStructures::markReachableFunctionsExternallyAccessible(DSNode *N,
33 hash_set<DSNode*> &Visited) {
34 if (!N || Visited.count(N)) return;
37 for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i) {
38 DSNodeHandle &NH = N->getLink(i*N->getPointerSize());
39 if (DSNode *NN = NH.getNode()) {
40 const std::vector<GlobalValue*> &Globals = NN->getGlobals();
41 for (unsigned G = 0, e = Globals.size(); G != e; ++G)
42 if (Function *F = dyn_cast<Function>(Globals[G]))
43 ArgsRemainIncomplete.insert(F);
45 markReachableFunctionsExternallyAccessible(NN, Visited);
51 // run - Calculate the top down data structure graphs for each function in the
54 bool TDDataStructures::run(Module &M) {
55 BUDataStructures &BU = getAnalysis<BUDataStructures>();
56 GlobalsGraph = new DSGraph(BU.getGlobalsGraph());
57 GlobalsGraph->setPrintAuxCalls();
59 // Figure out which functions must not mark their arguments complete because
60 // they are accessible outside this compilation unit. Currently, these
61 // arguments are functions which are reachable by global variables in the
63 const DSGraph::ScalarMapTy &GGSM = GlobalsGraph->getScalarMap();
64 hash_set<DSNode*> Visited;
65 for (DSGraph::ScalarMapTy::const_iterator I = GGSM.begin(), E = GGSM.end();
67 if (isa<GlobalValue>(I->first))
68 markReachableFunctionsExternallyAccessible(I->second.getNode(), Visited);
70 // Loop over unresolved call nodes. Any functions passed into (but not
71 // returned!) from unresolvable call nodes may be invoked outside of the
73 const std::vector<DSCallSite> &Calls = GlobalsGraph->getAuxFunctionCalls();
74 for (unsigned i = 0, e = Calls.size(); i != e; ++i) {
75 const DSCallSite &CS = Calls[i];
76 for (unsigned arg = 0, e = CS.getNumPtrArgs(); arg != e; ++arg)
77 markReachableFunctionsExternallyAccessible(CS.getPtrArg(arg).getNode(),
82 // Functions without internal linkage also have unknown incoming arguments!
83 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
84 if (!I->isExternal() && !I->hasInternalLinkage())
85 ArgsRemainIncomplete.insert(I);
87 // We want to traverse the call graph in reverse post-order. To do this, we
88 // calculate a post-order traversal, then reverse it.
89 hash_set<DSGraph*> VisitedGraph;
90 std::vector<DSGraph*> PostOrder;
91 const BUDataStructures::ActualCalleesTy &ActualCallees =
92 getAnalysis<BUDataStructures>().getActualCallees();
94 // Calculate top-down from main...
95 if (Function *F = M.getMainFunction())
96 ComputePostOrder(*F, VisitedGraph, PostOrder, ActualCallees);
98 // Next calculate the graphs for each unreachable function...
99 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
100 ComputePostOrder(*I, VisitedGraph, PostOrder, ActualCallees);
102 VisitedGraph.clear(); // Release memory!
104 // Visit each of the graphs in reverse post-order now!
105 while (!PostOrder.empty()) {
106 inlineGraphIntoCallees(*PostOrder.back());
107 PostOrder.pop_back();
110 ArgsRemainIncomplete.clear();
115 DSGraph &TDDataStructures::getOrCreateDSGraph(Function &F) {
116 DSGraph *&G = DSInfo[&F];
117 if (G == 0) { // Not created yet? Clone BU graph...
118 G = new DSGraph(getAnalysis<BUDataStructures>().getDSGraph(F));
119 G->getAuxFunctionCalls().clear();
120 G->setPrintAuxCalls();
121 G->setGlobalsGraph(GlobalsGraph);
127 void TDDataStructures::ComputePostOrder(Function &F,hash_set<DSGraph*> &Visited,
128 std::vector<DSGraph*> &PostOrder,
129 const BUDataStructures::ActualCalleesTy &ActualCallees) {
130 if (F.isExternal()) return;
131 DSGraph &G = getOrCreateDSGraph(F);
132 if (Visited.count(&G)) return;
135 // Recursively traverse all of the callee graphs.
136 const std::vector<DSCallSite> &FunctionCalls = G.getFunctionCalls();
138 for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i) {
139 Instruction *CallI = FunctionCalls[i].getCallSite().getInstruction();
140 std::pair<BUDataStructures::ActualCalleesTy::const_iterator,
141 BUDataStructures::ActualCalleesTy::const_iterator>
142 IP = ActualCallees.equal_range(CallI);
144 for (BUDataStructures::ActualCalleesTy::const_iterator I = IP.first;
146 ComputePostOrder(*I->second, Visited, PostOrder, ActualCallees);
149 PostOrder.push_back(&G);
156 // releaseMemory - If the pass pipeline is done with this pass, we can release
157 // our memory... here...
159 // FIXME: This should be releaseMemory and will work fine, except that LoadVN
160 // has no way to extend the lifetime of the pass, which screws up ds-aa.
162 void TDDataStructures::releaseMyMemory() {
163 for (hash_map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
164 E = DSInfo.end(); I != E; ++I) {
165 I->second->getReturnNodes().erase(I->first);
166 if (I->second->getReturnNodes().empty())
170 // Empty map so next time memory is released, data structures are not
177 void TDDataStructures::inlineGraphIntoCallees(DSGraph &Graph) {
178 // Recompute the Incomplete markers and eliminate unreachable nodes.
179 Graph.removeTriviallyDeadNodes();
180 Graph.maskIncompleteMarkers();
182 // If any of the functions has incomplete incoming arguments, don't mark any
183 // of them as complete.
184 bool HasIncompleteArgs = false;
185 const DSGraph::ReturnNodesTy &GraphReturnNodes = Graph.getReturnNodes();
186 for (DSGraph::ReturnNodesTy::const_iterator I = GraphReturnNodes.begin(),
187 E = GraphReturnNodes.end(); I != E; ++I)
188 if (ArgsRemainIncomplete.count(I->first)) {
189 HasIncompleteArgs = true;
193 // Now fold in the necessary globals from the GlobalsGraph. A global G
194 // must be folded in if it exists in the current graph (i.e., is not dead)
195 // and it was not inlined from any of my callers. If it was inlined from
196 // a caller, it would have been fully consistent with the GlobalsGraph
197 // in the caller so folding in is not necessary. Otherwise, this node came
198 // solely from this function's BU graph and so has to be made consistent.
200 Graph.updateFromGlobalGraph();
202 // Recompute the Incomplete markers. Depends on whether args are complete
204 = HasIncompleteArgs ? DSGraph::MarkFormalArgs : DSGraph::IgnoreFormalArgs;
205 Graph.markIncompleteNodes(Flags | DSGraph::IgnoreGlobals);
207 // Delete dead nodes. Treat globals that are unreachable as dead also.
208 Graph.removeDeadNodes(DSGraph::RemoveUnreachableGlobals);
210 // We are done with computing the current TD Graph! Now move on to
211 // inlining the current graph into the graphs for its callees, if any.
213 const std::vector<DSCallSite> &FunctionCalls = Graph.getFunctionCalls();
214 if (FunctionCalls.empty()) {
215 DEBUG(std::cerr << " [TD] No callees for: " << Graph.getFunctionNames()
220 // Now that we have information about all of the callees, propagate the
221 // current graph into the callees. Clone only the reachable subgraph at
222 // each call-site, not the entire graph (even though the entire graph
223 // would be cloned only once, this should still be better on average).
225 DEBUG(std::cerr << " [TD] Inlining '" << Graph.getFunctionNames() <<"' into "
226 << FunctionCalls.size() << " call nodes.\n");
228 const BUDataStructures::ActualCalleesTy &ActualCallees =
229 getAnalysis<BUDataStructures>().getActualCallees();
231 // Loop over all the call sites and all the callees at each call site. Build
232 // a mapping from called DSGraph's to the call sites in this function that
233 // invoke them. This is useful because we can be more efficient if there are
234 // multiple call sites to the callees in the graph from this caller.
235 std::multimap<DSGraph*, std::pair<Function*, const DSCallSite*> > CallSites;
237 for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i) {
238 Instruction *CallI = FunctionCalls[i].getCallSite().getInstruction();
239 // For each function in the invoked function list at this call site...
240 std::pair<BUDataStructures::ActualCalleesTy::const_iterator,
241 BUDataStructures::ActualCalleesTy::const_iterator>
242 IP = ActualCallees.equal_range(CallI);
243 // Loop over each actual callee at this call site
244 for (BUDataStructures::ActualCalleesTy::const_iterator I = IP.first;
245 I != IP.second; ++I) {
246 DSGraph& CalleeGraph = getDSGraph(*I->second);
247 assert(&CalleeGraph != &Graph && "TD need not inline graph into self!");
249 CallSites.insert(std::make_pair(&CalleeGraph,
250 std::make_pair(I->second, &FunctionCalls[i])));
254 // Now that we built the mapping, actually perform the inlining a callee graph
256 std::multimap<DSGraph*,std::pair<Function*,const DSCallSite*> >::iterator CSI;
257 for (CSI = CallSites.begin(); CSI != CallSites.end(); ) {
258 DSGraph &CalleeGraph = *CSI->first;
259 // Iterate through all of the call sites of this graph, cloning and merging
260 // any nodes required by the call.
261 ReachabilityCloner RC(CalleeGraph, Graph, DSGraph::StripModRefBits);
263 // Clone over any global nodes that appear in both graphs.
264 for (DSGraph::ScalarMapTy::const_iterator
265 SI = CalleeGraph.getScalarMap().begin(),
266 SE = CalleeGraph.getScalarMap().end(); SI != SE; ++SI)
267 if (GlobalValue *GV = dyn_cast<GlobalValue>(SI->first)) {
268 DSGraph::ScalarMapTy::const_iterator GI = Graph.getScalarMap().find(GV);
269 if (GI != Graph.getScalarMap().end())
270 RC.merge(SI->second, GI->second);
273 // Loop over all of the distinct call sites in the caller of the callee.
274 for (; CSI != CallSites.end() && CSI->first == &CalleeGraph; ++CSI) {
275 Function &CF = *CSI->second.first;
276 const DSCallSite &CS = *CSI->second.second;
277 DEBUG(std::cerr << " [TD] Resolving arguments for callee graph '"
278 << CalleeGraph.getFunctionNames()
279 << "': " << CF.getFunctionType()->getNumParams()
280 << " args\n at call site (DSCallSite*) 0x" << &CS << "\n");
282 // Get the formal argument and return nodes for the called function and
283 // merge them with the cloned subgraph.
284 RC.mergeCallSite(CalleeGraph.getCallSiteForArguments(CF), CS);
289 DEBUG(std::cerr << " [TD] Done inlining into callees for: "
290 << Graph.getFunctionNames() << " [" << Graph.getGraphSize() << "+"
291 << Graph.getFunctionCalls().size() << "]\n");