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"
25 RegisterAnalysis<TDDataStructures> // Register the pass
26 Y("tddatastructure", "Top-down Data Structure Analysis");
28 Statistic<> NumTDInlines("tddatastructures", "Number of graphs inlined");
31 void TDDataStructures::markReachableFunctionsExternallyAccessible(DSNode *N,
32 hash_set<DSNode*> &Visited) {
33 if (!N || Visited.count(N)) return;
36 for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i) {
37 DSNodeHandle &NH = N->getLink(i*N->getPointerSize());
38 if (DSNode *NN = NH.getNode()) {
39 const std::vector<GlobalValue*> &Globals = NN->getGlobals();
40 for (unsigned G = 0, e = Globals.size(); G != e; ++G)
41 if (Function *F = dyn_cast<Function>(Globals[G]))
42 ArgsRemainIncomplete.insert(F);
44 markReachableFunctionsExternallyAccessible(NN, Visited);
50 // run - Calculate the top down data structure graphs for each function in the
53 bool TDDataStructures::run(Module &M) {
54 BUDataStructures &BU = getAnalysis<BUDataStructures>();
55 GlobalsGraph = new DSGraph(BU.getGlobalsGraph());
56 GlobalsGraph->setPrintAuxCalls();
58 // Figure out which functions must not mark their arguments complete because
59 // they are accessible outside this compilation unit. Currently, these
60 // arguments are functions which are reachable by global variables in the
62 const DSGraph::ScalarMapTy &GGSM = GlobalsGraph->getScalarMap();
63 hash_set<DSNode*> Visited;
64 for (DSGraph::ScalarMapTy::const_iterator I = GGSM.begin(), E = GGSM.end();
66 if (isa<GlobalValue>(I->first))
67 markReachableFunctionsExternallyAccessible(I->second.getNode(), Visited);
69 // Loop over unresolved call nodes. Any functions passed into (but not
70 // returned!?) from unresolvable call nodes may be invoked outside of the
72 const std::vector<DSCallSite> &Calls = GlobalsGraph->getAuxFunctionCalls();
73 for (unsigned i = 0, e = Calls.size(); i != e; ++i) {
74 const DSCallSite &CS = Calls[i];
75 for (unsigned arg = 0, e = CS.getNumPtrArgs(); arg != e; ++arg)
76 markReachableFunctionsExternallyAccessible(CS.getPtrArg(arg).getNode(),
81 // Functions without internal linkage also have unknown incoming arguments!
82 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
83 if (!I->isExternal() && !I->hasInternalLinkage())
84 ArgsRemainIncomplete.insert(I);
86 // We want to traverse the call graph in reverse post-order. To do this, we
87 // calculate a post-order traversal, then reverse it.
88 hash_set<DSGraph*> VisitedGraph;
89 std::vector<DSGraph*> PostOrder;
90 const BUDataStructures::ActualCalleesTy &ActualCallees =
91 getAnalysis<BUDataStructures>().getActualCallees();
93 // Calculate top-down from main...
94 if (Function *F = M.getMainFunction())
95 ComputePostOrder(*F, VisitedGraph, PostOrder, ActualCallees);
97 // Next calculate the graphs for each unreachable function...
98 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
99 ComputePostOrder(*I, VisitedGraph, PostOrder, ActualCallees);
101 VisitedGraph.clear(); // Release memory!
103 // Visit each of the graphs in reverse post-order now!
104 while (!PostOrder.empty()) {
105 inlineGraphIntoCallees(*PostOrder.back());
106 PostOrder.pop_back();
109 ArgsRemainIncomplete.clear();
114 DSGraph &TDDataStructures::getOrCreateDSGraph(Function &F) {
115 DSGraph *&G = DSInfo[&F];
116 if (G == 0) { // Not created yet? Clone BU graph...
117 G = new DSGraph(getAnalysis<BUDataStructures>().getDSGraph(F));
118 G->getAuxFunctionCalls().clear();
119 G->setPrintAuxCalls();
120 G->setGlobalsGraph(GlobalsGraph);
126 void TDDataStructures::ComputePostOrder(Function &F,hash_set<DSGraph*> &Visited,
127 std::vector<DSGraph*> &PostOrder,
128 const BUDataStructures::ActualCalleesTy &ActualCallees) {
129 if (F.isExternal()) return;
130 DSGraph &G = getOrCreateDSGraph(F);
131 if (Visited.count(&G)) return;
134 // Recursively traverse all of the callee graphs.
135 const std::vector<DSCallSite> &FunctionCalls = G.getFunctionCalls();
137 for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i) {
138 Instruction *CallI = FunctionCalls[i].getCallSite().getInstruction();
139 std::pair<BUDataStructures::ActualCalleesTy::const_iterator,
140 BUDataStructures::ActualCalleesTy::const_iterator>
141 IP = ActualCallees.equal_range(CallI);
143 for (BUDataStructures::ActualCalleesTy::const_iterator I = IP.first;
145 ComputePostOrder(*I->second, Visited, PostOrder, ActualCallees);
148 PostOrder.push_back(&G);
155 // releaseMemory - If the pass pipeline is done with this pass, we can release
156 // our memory... here...
158 // FIXME: This should be releaseMemory and will work fine, except that LoadVN
159 // has no way to extend the lifetime of the pass, which screws up ds-aa.
161 void TDDataStructures::releaseMyMemory() {
162 for (hash_map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
163 E = DSInfo.end(); I != E; ++I) {
164 I->second->getReturnNodes().erase(I->first);
165 if (I->second->getReturnNodes().empty())
169 // Empty map so next time memory is released, data structures are not
176 void TDDataStructures::inlineGraphIntoCallees(DSGraph &Graph) {
177 // Recompute the Incomplete markers and eliminate unreachable nodes.
178 Graph.removeTriviallyDeadNodes();
179 Graph.maskIncompleteMarkers();
181 // If any of the functions has incomplete incoming arguments, don't mark any
182 // of them as complete.
183 bool HasIncompleteArgs = false;
184 const DSGraph::ReturnNodesTy &GraphReturnNodes = Graph.getReturnNodes();
185 for (DSGraph::ReturnNodesTy::const_iterator I = GraphReturnNodes.begin(),
186 E = GraphReturnNodes.end(); I != E; ++I)
187 if (ArgsRemainIncomplete.count(I->first)) {
188 HasIncompleteArgs = true;
192 // Now fold in the necessary globals from the GlobalsGraph. A global G
193 // must be folded in if it exists in the current graph (i.e., is not dead)
194 // and it was not inlined from any of my callers. If it was inlined from
195 // a caller, it would have been fully consistent with the GlobalsGraph
196 // in the caller so folding in is not necessary. Otherwise, this node came
197 // solely from this function's BU graph and so has to be made consistent.
199 Graph.updateFromGlobalGraph();
201 // Recompute the Incomplete markers. Depends on whether args are complete
203 = HasIncompleteArgs ? DSGraph::MarkFormalArgs : DSGraph::IgnoreFormalArgs;
204 Graph.markIncompleteNodes(Flags | DSGraph::IgnoreGlobals);
206 // Delete dead nodes. Treat globals that are unreachable as dead also.
207 Graph.removeDeadNodes(DSGraph::RemoveUnreachableGlobals);
209 // We are done with computing the current TD Graph! Now move on to
210 // inlining the current graph into the graphs for its callees, if any.
212 const std::vector<DSCallSite> &FunctionCalls = Graph.getFunctionCalls();
213 if (FunctionCalls.empty()) {
214 DEBUG(std::cerr << " [TD] No callees for: " << Graph.getFunctionNames()
219 // Now that we have information about all of the callees, propagate the
220 // current graph into the callees. Clone only the reachable subgraph at
221 // each call-site, not the entire graph (even though the entire graph
222 // would be cloned only once, this should still be better on average).
224 DEBUG(std::cerr << " [TD] Inlining '" << Graph.getFunctionNames() <<"' into "
225 << FunctionCalls.size() << " call nodes.\n");
227 const BUDataStructures::ActualCalleesTy &ActualCallees =
228 getAnalysis<BUDataStructures>().getActualCallees();
230 // Loop over all the call sites and all the callees at each call site.
231 // Clone and merge the reachable subgraph from the call into callee's graph.
233 for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i) {
234 Instruction *CallI = FunctionCalls[i].getCallSite().getInstruction();
235 // For each function in the invoked function list at this call site...
236 std::pair<BUDataStructures::ActualCalleesTy::const_iterator,
237 BUDataStructures::ActualCalleesTy::const_iterator>
238 IP = ActualCallees.equal_range(CallI);
240 // Multiple callees may have the same graph, so try to inline and merge
241 // only once for each <callSite,calleeGraph> pair, not once for each
242 // <callSite,calleeFunction> pair; the latter will be correct but slower.
243 hash_set<DSGraph*> GraphsSeen;
245 // Loop over each actual callee at this call site
246 for (BUDataStructures::ActualCalleesTy::const_iterator I = IP.first;
247 I != IP.second; ++I) {
248 DSGraph& CalleeGraph = getDSGraph(*I->second);
249 assert(&CalleeGraph != &Graph && "TD need not inline graph into self!");
251 // if this callee graph is already done at this site, skip this callee
252 if (GraphsSeen.find(&CalleeGraph) != GraphsSeen.end())
254 GraphsSeen.insert(&CalleeGraph);
256 // Get the root nodes for cloning the reachable subgraph into each callee:
257 // -- all global nodes that appear in both the caller and the callee
258 // -- return value at this call site, if any
259 // -- actual arguments passed at this call site
260 // -- callee node at this call site, if this is an indirect call (this may
261 // not be needed for merging, but allows us to create CS and therefore
262 // simplify the merging below).
263 hash_set<const DSNode*> RootNodeSet;
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 RootNodeSet.insert(GI->second.getNode());
273 if (const DSNode* RetNode = FunctionCalls[i].getRetVal().getNode())
274 RootNodeSet.insert(RetNode);
276 for (unsigned j=0, N=FunctionCalls[i].getNumPtrArgs(); j < N; ++j)
277 if (const DSNode* ArgTarget = FunctionCalls[i].getPtrArg(j).getNode())
278 RootNodeSet.insert(ArgTarget);
280 if (FunctionCalls[i].isIndirectCall())
281 RootNodeSet.insert(FunctionCalls[i].getCalleeNode());
283 DEBUG(std::cerr << " [TD] Resolving arguments for callee graph '"
284 << CalleeGraph.getFunctionNames()
285 << "': " << I->second->getFunctionType()->getNumParams()
286 << " args\n at call site (DSCallSite*) 0x"
287 << &FunctionCalls[i] << "\n");
289 DSGraph::NodeMapTy NodeMapInCallee; // map from nodes to clones in callee
290 DSGraph::NodeMapTy CompletedMap; // unused map for nodes not to do
291 CalleeGraph.cloneReachableSubgraph(Graph, RootNodeSet,
292 NodeMapInCallee, CompletedMap,
293 DSGraph::StripModRefBits |
294 DSGraph::KeepAllocaBit);
296 // Transform our call site info into the cloned version for CalleeGraph
297 DSCallSite CS(FunctionCalls[i], NodeMapInCallee);
299 // Get the formal argument and return nodes for the called function
300 // and merge them with the cloned subgraph. Global nodes were merged
301 // already by cloneReachableSubgraph() above.
302 CalleeGraph.getCallSiteForArguments(*I->second).mergeWith(CS);
308 DEBUG(std::cerr << " [TD] Done inlining into callees for: "
309 << Graph.getFunctionNames() << " [" << Graph.getGraphSize() << "+"
310 << Graph.getFunctionCalls().size() << "]\n");