1 //===- DataStructure.cpp - Implement the core data structure analysis -----===//
3 // This file implements the core data structure functionality.
5 //===----------------------------------------------------------------------===//
7 #include "llvm/Module.h"
8 #include "llvm/DerivedTypes.h"
9 #include "Support/STLExtras.h"
10 #include "Support/StatisticReporter.h"
11 #include "Support/STLExtras.h"
14 #include "llvm/Analysis/DataStructure.h"
18 static RegisterAnalysis<LocalDataStructures>
19 X("datastructure", "Local Data Structure Analysis");
20 AnalysisID LocalDataStructures::ID(AnalysisID::create<LocalDataStructures>());
22 //===----------------------------------------------------------------------===//
23 // DSNode Implementation
24 //===----------------------------------------------------------------------===//
26 DSNode::DSNode(enum NodeTy NT, const Type *T) : Ty(T), NodeType(NT) {
27 // If this node has any fields, allocate them now, but leave them null.
28 switch (T->getPrimitiveID()) {
29 case Type::PointerTyID: Links.resize(1); break;
30 case Type::ArrayTyID: Links.resize(1); break;
31 case Type::StructTyID:
32 Links.resize(cast<StructType>(T)->getNumContainedTypes());
38 // DSNode copy constructor... do not copy over the referrers list!
39 DSNode::DSNode(const DSNode &N)
40 : Ty(N.Ty), Links(N.Links), Globals(N.Globals), NodeType(N.NodeType) {
43 void DSNode::removeReferrer(DSNodeHandle *H) {
44 // Search backwards, because we depopulate the list from the back for
45 // efficiency (because it's a vector).
46 vector<DSNodeHandle*>::reverse_iterator I =
47 std::find(Referrers.rbegin(), Referrers.rend(), H);
48 assert(I != Referrers.rend() && "Referrer not pointing to node!");
49 Referrers.erase(I.base()-1);
52 // addGlobal - Add an entry for a global value to the Globals list. This also
53 // marks the node with the 'G' flag if it does not already have it.
55 void DSNode::addGlobal(GlobalValue *GV) {
56 // Keep the list sorted.
57 vector<GlobalValue*>::iterator I =
58 std::lower_bound(Globals.begin(), Globals.end(), GV);
60 if (I == Globals.end() || *I != GV) {
61 assert(GV->getType()->getElementType() == Ty);
62 Globals.insert(I, GV);
63 NodeType |= GlobalNode;
68 // addEdgeTo - Add an edge from the current node to the specified node. This
69 // can cause merging of nodes in the graph.
71 void DSNode::addEdgeTo(unsigned LinkNo, DSNode *N) {
72 assert(LinkNo < Links.size() && "LinkNo out of range!");
73 if (N == 0 || Links[LinkNo] == N) return; // Nothing to do
74 if (Links[LinkNo] == 0) { // No merging to perform
79 // Merge the two nodes...
80 Links[LinkNo]->mergeWith(N);
84 // mergeWith - Merge this node into the specified node, moving all links to and
85 // from the argument node into the current node. The specified node may be a
86 // null pointer (in which case, nothing happens).
88 void DSNode::mergeWith(DSNode *N) {
89 if (N == 0 || N == this) return; // Noop
90 assert(N->Ty == Ty && N->Links.size() == Links.size() &&
91 "Cannot merge nodes of two different types!");
93 // Remove all edges pointing at N, causing them to point to 'this' instead.
94 while (!N->Referrers.empty())
95 *N->Referrers.back() = this;
97 // Make all of the outgoing links of N now be outgoing links of this. This
98 // can cause recursive merging!
100 for (unsigned i = 0, e = Links.size(); i != e; ++i) {
101 addEdgeTo(i, N->Links[i]);
102 N->Links[i] = 0; // Reduce unneccesary edges in graph. N is dead
105 // Merge the node types
106 NodeType |= N->NodeType;
107 N->NodeType = 0; // N is now a dead node.
109 // Merge the globals list...
110 if (!N->Globals.empty()) {
111 // Save the current globals off to the side...
112 vector<GlobalValue*> OldGlobals(Globals);
114 // Resize the globals vector to be big enough to hold both of them...
115 Globals.resize(Globals.size()+N->Globals.size());
117 // Merge the two sorted globals lists together...
118 std::merge(OldGlobals.begin(), OldGlobals.end(),
119 N->Globals.begin(), N->Globals.end(), Globals.begin());
121 // Erase duplicate entries from the globals list...
122 Globals.erase(std::unique(Globals.begin(), Globals.end()), Globals.end());
124 // Delete the globals from the old node...
129 //===----------------------------------------------------------------------===//
130 // DSGraph Implementation
131 //===----------------------------------------------------------------------===//
133 DSGraph::DSGraph(const DSGraph &G) : Func(G.Func) {
134 std::map<const DSNode*, DSNode*> NodeMap; // ignored
135 RetNode = cloneInto(G, ValueMap, NodeMap, false);
138 DSGraph::~DSGraph() {
139 FunctionCalls.clear();
140 OrigFunctionCalls.clear();
145 // Drop all intra-node references, so that assertions don't fail...
146 std::for_each(Nodes.begin(), Nodes.end(),
147 std::mem_fun(&DSNode::dropAllReferences));
150 // Delete all of the nodes themselves...
151 std::for_each(Nodes.begin(), Nodes.end(), deleter<DSNode>);
154 // dump - Allow inspection of graph in a debugger.
155 void DSGraph::dump() const { print(std::cerr); }
158 // cloneInto - Clone the specified DSGraph into the current graph, returning the
159 // Return node of the graph. The translated ValueMap for the old function is
160 // filled into the OldValMap member. If StripLocals is set to true, Scalar and
161 // Alloca markers are removed from the graph, as the graph is being cloned into
162 // a calling function's graph.
164 DSNode *DSGraph::cloneInto(const DSGraph &G,
165 std::map<Value*, DSNodeHandle> &OldValMap,
166 std::map<const DSNode*, DSNode*> &OldNodeMap,
169 assert(OldNodeMap.size()==0 && "Return argument OldNodeMap should be empty");
171 OldNodeMap[0] = 0; // Null pointer maps to null
173 unsigned FN = Nodes.size(); // FirstNode...
175 // Duplicate all of the nodes, populating the node map...
176 Nodes.reserve(FN+G.Nodes.size());
177 for (unsigned i = 0, e = G.Nodes.size(); i != e; ++i) {
178 DSNode *Old = G.Nodes[i], *New = new DSNode(*Old);
179 Nodes.push_back(New);
180 OldNodeMap[Old] = New;
183 // Rewrite the links in the nodes to point into the current graph now.
184 for (unsigned i = FN, e = Nodes.size(); i != e; ++i)
185 for (unsigned j = 0, e = Nodes[i]->getNumLinks(); j != e; ++j)
186 Nodes[i]->setLink(j, OldNodeMap[Nodes[i]->getLink(j)]);
188 // If we are inlining this graph into the called function graph, remove local
191 for (unsigned i = FN, e = Nodes.size(); i != e; ++i)
192 Nodes[i]->NodeType &= ~(DSNode::AllocaNode | DSNode::ScalarNode);
194 // Copy the value map...
195 for (std::map<Value*, DSNodeHandle>::const_iterator I = G.ValueMap.begin(),
196 E = G.ValueMap.end(); I != E; ++I)
197 OldValMap[I->first] = OldNodeMap[I->second];
199 // Copy the function calls list...
200 unsigned FC = FunctionCalls.size(); // FirstCall
201 FunctionCalls.reserve(FC+G.FunctionCalls.size());
202 for (unsigned i = 0, e = G.FunctionCalls.size(); i != e; ++i) {
203 FunctionCalls.push_back(std::vector<DSNodeHandle>());
204 FunctionCalls[FC+i].reserve(G.FunctionCalls[i].size());
205 for (unsigned j = 0, e = G.FunctionCalls[i].size(); j != e; ++j)
206 FunctionCalls[FC+i].push_back(OldNodeMap[G.FunctionCalls[i][j]]);
209 // Copy the list of unresolved callers
210 PendingCallers.insert(PendingCallers.end(),
211 G.PendingCallers.begin(), G.PendingCallers.end());
213 // Return the returned node pointer...
214 return OldNodeMap[G.RetNode];
218 // markIncompleteNodes - Mark the specified node as having contents that are not
219 // known with the current analysis we have performed. Because a node makes all
220 // of the nodes it can reach imcomplete if the node itself is incomplete, we
221 // must recursively traverse the data structure graph, marking all reachable
222 // nodes as incomplete.
224 static void markIncompleteNode(DSNode *N) {
225 // Stop recursion if no node, or if node already marked...
226 if (N == 0 || (N->NodeType & DSNode::Incomplete)) return;
228 // Actually mark the node
229 N->NodeType |= DSNode::Incomplete;
231 // Recusively process children...
232 for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i)
233 markIncompleteNode(N->getLink(i));
237 // markIncompleteNodes - Traverse the graph, identifying nodes that may be
238 // modified by other functions that have not been resolved yet. This marks
239 // nodes that are reachable through three sources of "unknownness":
241 // Global Variables, Function Calls, and Incoming Arguments
243 // For any node that may have unknown components (because something outside the
244 // scope of current analysis may have modified it), the 'Incomplete' flag is
245 // added to the NodeType.
247 void DSGraph::markIncompleteNodes() {
248 // Mark any incoming arguments as incomplete...
249 for (Function::aiterator I = Func.abegin(), E = Func.aend(); I != E; ++I)
250 if (isa<PointerType>(I->getType()))
251 markIncompleteNode(ValueMap[I]->getLink(0));
253 // Mark stuff passed into functions calls as being incomplete...
254 for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i) {
255 vector<DSNodeHandle> &Args = FunctionCalls[i];
256 // Then the return value is certainly incomplete!
257 markIncompleteNode(Args[0]);
259 // The call does not make the function argument incomplete...
261 // All arguments to the function call are incomplete though!
262 for (unsigned i = 2, e = Args.size(); i != e; ++i)
263 markIncompleteNode(Args[i]);
266 // Mark all of the nodes pointed to by global or cast nodes as incomplete...
267 for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
268 if (Nodes[i]->NodeType & (DSNode::GlobalNode | DSNode::CastNode)) {
269 DSNode *N = Nodes[i];
270 for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i)
271 markIncompleteNode(N->getLink(i));
275 // isNodeDead - This method checks to see if a node is dead, and if it isn't, it
276 // checks to see if there are simple transformations that it can do to make it
279 bool DSGraph::isNodeDead(DSNode *N) {
280 // Is it a trivially dead shadow node...
281 if (N->getReferrers().empty() && N->NodeType == 0)
284 // Is it a function node or some other trivially unused global?
285 if ((N->NodeType & ~DSNode::GlobalNode) == 0 &&
286 N->getNumLinks() == 0 &&
287 N->getReferrers().size() == N->getGlobals().size()) {
289 // Remove the globals from the valuemap, so that the referrer count will go
291 while (!N->getGlobals().empty()) {
292 GlobalValue *GV = N->getGlobals().back();
293 N->getGlobals().pop_back();
296 assert(N->getReferrers().empty() && "Referrers should all be gone now!");
304 // removeTriviallyDeadNodes - After the graph has been constructed, this method
305 // removes all unreachable nodes that are created because they got merged with
306 // other nodes in the graph. These nodes will all be trivially unreachable, so
307 // we don't have to perform any non-trivial analysis here.
309 void DSGraph::removeTriviallyDeadNodes() {
310 for (unsigned i = 0; i != Nodes.size(); ++i)
311 if (isNodeDead(Nodes[i])) { // This node is dead!
312 delete Nodes[i]; // Free memory...
313 Nodes.erase(Nodes.begin()+i--); // Remove from node list...
316 // Remove trivially identical function calls
317 unsigned NumFns = FunctionCalls.size();
318 std::sort(FunctionCalls.begin(), FunctionCalls.end());
319 FunctionCalls.erase(std::unique(FunctionCalls.begin(), FunctionCalls.end()),
320 FunctionCalls.end());
322 DEBUG(if (NumFns != FunctionCalls.size())
323 std::cerr << "Merged " << (NumFns-FunctionCalls.size())
324 << " call nodes in " << Func.getName() << "\n";);
328 // markAlive - Simple graph traverser that recursively walks the graph marking
329 // stuff to be alive.
331 static void markAlive(DSNode *N, std::set<DSNode*> &Alive) {
332 if (N == 0 || Alive.count(N)) return;
335 for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i)
336 markAlive(N->getLink(i), Alive);
340 // removeDeadNodes - Use a more powerful reachability analysis to eliminate
341 // subgraphs that are unreachable. This often occurs because the data
342 // structure doesn't "escape" into it's caller, and thus should be eliminated
343 // from the caller's graph entirely. This is only appropriate to use when
346 void DSGraph::removeDeadNodes() {
347 // Reduce the amount of work we have to do...
348 removeTriviallyDeadNodes();
350 // FIXME: Merge nontrivially identical call nodes...
352 // Alive - a set that holds all nodes found to be reachable/alive.
353 std::set<DSNode*> Alive;
355 // Mark all nodes reachable by call nodes as alive...
356 for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i)
357 for (unsigned j = 0, e = FunctionCalls[i].size(); j != e; ++j)
358 markAlive(FunctionCalls[i][j], Alive);
360 for (unsigned i = 0, e = OrigFunctionCalls.size(); i != e; ++i)
361 for (unsigned j = 0, e = OrigFunctionCalls[i].size(); j != e; ++j)
362 markAlive(OrigFunctionCalls[i][j], Alive);
364 // Mark all nodes reachable by scalar, global, or incomplete nodes as
366 for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
367 if (Nodes[i]->NodeType & (DSNode::ScalarNode | DSNode::GlobalNode))
368 markAlive(Nodes[i], Alive);
370 // Loop over all unreachable nodes, dropping their references...
371 std::vector<DSNode*> DeadNodes;
372 DeadNodes.reserve(Nodes.size()); // Only one allocation is allowed.
373 for (unsigned i = 0; i != Nodes.size(); ++i)
374 if (!Alive.count(Nodes[i])) {
375 DSNode *N = Nodes[i];
376 Nodes.erase(Nodes.begin()+i--); // Erase node from alive list.
377 DeadNodes.push_back(N); // Add node to our list of dead nodes
378 N->dropAllReferences(); // Drop all outgoing edges
381 // The return value is alive as well...
382 markAlive(RetNode, Alive);
384 // Delete all dead nodes...
385 std::for_each(DeadNodes.begin(), DeadNodes.end(), deleter<DSNode>);
390 // maskNodeTypes - Apply a mask to all of the node types in the graph. This
391 // is useful for clearing out markers like Scalar or Incomplete.
393 void DSGraph::maskNodeTypes(unsigned char Mask) {
394 for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
395 Nodes[i]->NodeType &= Mask;
399 //===----------------------------------------------------------------------===//
400 // LocalDataStructures Implementation
401 //===----------------------------------------------------------------------===//
403 // releaseMemory - If the pass pipeline is done with this pass, we can release
404 // our memory... here...
406 void LocalDataStructures::releaseMemory() {
407 for (std::map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
408 E = DSInfo.end(); I != E; ++I)
411 // Empty map so next time memory is released, data structures are not
416 bool LocalDataStructures::run(Module &M) {
417 // Calculate all of the graphs...
418 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
419 if (!I->isExternal())
420 DSInfo.insert(std::make_pair(&*I, new DSGraph(*I)));