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 //===----------------------------------------------------------------------===//
19 // DSNode Implementation
20 //===----------------------------------------------------------------------===//
22 DSNode::DSNode(enum NodeTy NT, const Type *T) : Ty(T), NodeType(NT) {
23 // If this node has any fields, allocate them now, but leave them null.
24 switch (T->getPrimitiveID()) {
25 case Type::PointerTyID: Links.resize(1); break;
26 case Type::ArrayTyID: Links.resize(1); break;
27 case Type::StructTyID:
28 Links.resize(cast<StructType>(T)->getNumContainedTypes());
34 // DSNode copy constructor... do not copy over the referrers list!
35 DSNode::DSNode(const DSNode &N)
36 : Ty(N.Ty), Links(N.Links), Globals(N.Globals), NodeType(N.NodeType) {
39 void DSNode::removeReferrer(DSNodeHandle *H) {
40 // Search backwards, because we depopulate the list from the back for
41 // efficiency (because it's a vector).
42 vector<DSNodeHandle*>::reverse_iterator I =
43 std::find(Referrers.rbegin(), Referrers.rend(), H);
44 assert(I != Referrers.rend() && "Referrer not pointing to node!");
45 Referrers.erase(I.base()-1);
48 // addGlobal - Add an entry for a global value to the Globals list. This also
49 // marks the node with the 'G' flag if it does not already have it.
51 void DSNode::addGlobal(GlobalValue *GV) {
52 // Keep the list sorted.
53 vector<GlobalValue*>::iterator I =
54 std::lower_bound(Globals.begin(), Globals.end(), GV);
56 if (I == Globals.end() || *I != GV) {
57 assert(GV->getType()->getElementType() == Ty);
58 Globals.insert(I, GV);
59 NodeType |= GlobalNode;
64 // addEdgeTo - Add an edge from the current node to the specified node. This
65 // can cause merging of nodes in the graph.
67 void DSNode::addEdgeTo(unsigned LinkNo, DSNode *N) {
68 assert(LinkNo < Links.size() && "LinkNo out of range!");
69 if (N == 0 || Links[LinkNo] == N) return; // Nothing to do
70 if (Links[LinkNo] == 0) { // No merging to perform
75 // Merge the two nodes...
76 Links[LinkNo]->mergeWith(N);
80 // mergeWith - Merge this node into the specified node, moving all links to and
81 // from the argument node into the current node. The specified node may be a
82 // null pointer (in which case, nothing happens).
84 void DSNode::mergeWith(DSNode *N) {
85 if (N == 0 || N == this) return; // Noop
86 assert(N->Ty == Ty && N->Links.size() == Links.size() &&
87 "Cannot merge nodes of two different types!");
89 // Remove all edges pointing at N, causing them to point to 'this' instead.
90 while (!N->Referrers.empty())
91 *N->Referrers.back() = this;
93 // Make all of the outgoing links of N now be outgoing links of this. This
94 // can cause recursive merging!
96 for (unsigned i = 0, e = Links.size(); i != e; ++i) {
97 addEdgeTo(i, N->Links[i]);
98 N->Links[i] = 0; // Reduce unneccesary edges in graph. N is dead
101 // Merge the node types
102 NodeType |= N->NodeType;
103 N->NodeType = 0; // N is now a dead node.
105 // Merge the globals list...
106 if (!N->Globals.empty()) {
107 // Save the current globals off to the side...
108 vector<GlobalValue*> OldGlobals(Globals);
110 // Resize the globals vector to be big enough to hold both of them...
111 Globals.resize(Globals.size()+N->Globals.size());
113 // Merge the two sorted globals lists together...
114 std::merge(OldGlobals.begin(), OldGlobals.end(),
115 N->Globals.begin(), N->Globals.end(), Globals.begin());
117 // Erase duplicate entries from the globals list...
118 Globals.erase(std::unique(Globals.begin(), Globals.end()), Globals.end());
120 // Delete the globals from the old node...
125 //===----------------------------------------------------------------------===//
126 // DSGraph Implementation
127 //===----------------------------------------------------------------------===//
129 DSGraph::DSGraph(const DSGraph &G) : Func(G.Func) {
130 std::map<const DSNode*, DSNode*> NodeMap; // ignored
131 RetNode = cloneInto(G, ValueMap, NodeMap, false);
134 DSGraph::~DSGraph() {
135 FunctionCalls.clear();
136 OrigFunctionCalls.clear();
141 // Drop all intra-node references, so that assertions don't fail...
142 std::for_each(Nodes.begin(), Nodes.end(),
143 std::mem_fun(&DSNode::dropAllReferences));
146 // Delete all of the nodes themselves...
147 std::for_each(Nodes.begin(), Nodes.end(), deleter<DSNode>);
150 // dump - Allow inspection of graph in a debugger.
151 void DSGraph::dump() const { print(std::cerr); }
154 // cloneInto - Clone the specified DSGraph into the current graph, returning the
155 // Return node of the graph. The translated ValueMap for the old function is
156 // filled into the OldValMap member. If StripLocals is set to true, Scalar and
157 // Alloca markers are removed from the graph, as the graph is being cloned into
158 // a calling function's graph.
160 DSNode *DSGraph::cloneInto(const DSGraph &G,
161 std::map<Value*, DSNodeHandle> &OldValMap,
162 std::map<const DSNode*, DSNode*> &OldNodeMap,
165 assert(OldNodeMap.size()==0 && "Return argument OldNodeMap should be empty");
167 OldNodeMap[0] = 0; // Null pointer maps to null
169 unsigned FN = Nodes.size(); // FirstNode...
171 // Duplicate all of the nodes, populating the node map...
172 Nodes.reserve(FN+G.Nodes.size());
173 for (unsigned i = 0, e = G.Nodes.size(); i != e; ++i) {
174 DSNode *Old = G.Nodes[i], *New = new DSNode(*Old);
175 Nodes.push_back(New);
176 OldNodeMap[Old] = New;
179 // Rewrite the links in the nodes to point into the current graph now.
180 for (unsigned i = FN, e = Nodes.size(); i != e; ++i)
181 for (unsigned j = 0, e = Nodes[i]->getNumLinks(); j != e; ++j)
182 Nodes[i]->setLink(j, OldNodeMap[Nodes[i]->getLink(j)]);
184 // If we are inlining this graph into the called function graph, remove local
187 for (unsigned i = FN, e = Nodes.size(); i != e; ++i)
188 Nodes[i]->NodeType &= ~(DSNode::AllocaNode | DSNode::ScalarNode);
190 // Copy the value map...
191 for (std::map<Value*, DSNodeHandle>::const_iterator I = G.ValueMap.begin(),
192 E = G.ValueMap.end(); I != E; ++I)
193 OldValMap[I->first] = OldNodeMap[I->second];
195 // Copy the function calls list...
196 unsigned FC = FunctionCalls.size(); // FirstCall
197 FunctionCalls.reserve(FC+G.FunctionCalls.size());
198 for (unsigned i = 0, e = G.FunctionCalls.size(); i != e; ++i) {
199 FunctionCalls.push_back(std::vector<DSNodeHandle>());
200 FunctionCalls[FC+i].reserve(G.FunctionCalls[i].size());
201 for (unsigned j = 0, e = G.FunctionCalls[i].size(); j != e; ++j)
202 FunctionCalls[FC+i].push_back(OldNodeMap[G.FunctionCalls[i][j]]);
205 // Copy the list of unresolved callers
206 PendingCallers.insert(PendingCallers.end(),
207 G.PendingCallers.begin(), G.PendingCallers.end());
209 // Return the returned node pointer...
210 return OldNodeMap[G.RetNode];
214 // markIncompleteNodes - Mark the specified node as having contents that are not
215 // known with the current analysis we have performed. Because a node makes all
216 // of the nodes it can reach imcomplete if the node itself is incomplete, we
217 // must recursively traverse the data structure graph, marking all reachable
218 // nodes as incomplete.
220 static void markIncompleteNode(DSNode *N) {
221 // Stop recursion if no node, or if node already marked...
222 if (N == 0 || (N->NodeType & DSNode::Incomplete)) return;
224 // Actually mark the node
225 N->NodeType |= DSNode::Incomplete;
227 // Recusively process children...
228 for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i)
229 markIncompleteNode(N->getLink(i));
233 // markIncompleteNodes - Traverse the graph, identifying nodes that may be
234 // modified by other functions that have not been resolved yet. This marks
235 // nodes that are reachable through three sources of "unknownness":
237 // Global Variables, Function Calls, and Incoming Arguments
239 // For any node that may have unknown components (because something outside the
240 // scope of current analysis may have modified it), the 'Incomplete' flag is
241 // added to the NodeType.
243 void DSGraph::markIncompleteNodes() {
244 // Mark any incoming arguments as incomplete...
245 for (Function::aiterator I = Func.abegin(), E = Func.aend(); I != E; ++I)
246 if (isa<PointerType>(I->getType()))
247 markIncompleteNode(ValueMap[I]->getLink(0));
249 // Mark stuff passed into functions calls as being incomplete...
250 for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i) {
251 vector<DSNodeHandle> &Args = FunctionCalls[i];
252 // Then the return value is certainly incomplete!
253 markIncompleteNode(Args[0]);
255 // The call does not make the function argument incomplete...
257 // All arguments to the function call are incomplete though!
258 for (unsigned i = 2, e = Args.size(); i != e; ++i)
259 markIncompleteNode(Args[i]);
262 // Mark all of the nodes pointed to by global or cast nodes as incomplete...
263 for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
264 if (Nodes[i]->NodeType & (DSNode::GlobalNode | DSNode::CastNode)) {
265 DSNode *N = Nodes[i];
266 for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i)
267 markIncompleteNode(N->getLink(i));
271 // isNodeDead - This method checks to see if a node is dead, and if it isn't, it
272 // checks to see if there are simple transformations that it can do to make it
275 bool DSGraph::isNodeDead(DSNode *N) {
276 // Is it a trivially dead shadow node...
277 if (N->getReferrers().empty() && N->NodeType == 0)
280 // Is it a function node or some other trivially unused global?
281 if ((N->NodeType & ~DSNode::GlobalNode) == 0 &&
282 N->getNumLinks() == 0 &&
283 N->getReferrers().size() == N->getGlobals().size()) {
285 // Remove the globals from the valuemap, so that the referrer count will go
287 while (!N->getGlobals().empty()) {
288 GlobalValue *GV = N->getGlobals().back();
289 N->getGlobals().pop_back();
292 assert(N->getReferrers().empty() && "Referrers should all be gone now!");
300 // removeTriviallyDeadNodes - After the graph has been constructed, this method
301 // removes all unreachable nodes that are created because they got merged with
302 // other nodes in the graph. These nodes will all be trivially unreachable, so
303 // we don't have to perform any non-trivial analysis here.
305 void DSGraph::removeTriviallyDeadNodes() {
306 for (unsigned i = 0; i != Nodes.size(); ++i)
307 if (isNodeDead(Nodes[i])) { // This node is dead!
308 delete Nodes[i]; // Free memory...
309 Nodes.erase(Nodes.begin()+i--); // Remove from node list...
312 // Remove trivially identical function calls
313 unsigned NumFns = FunctionCalls.size();
314 std::sort(FunctionCalls.begin(), FunctionCalls.end());
315 FunctionCalls.erase(std::unique(FunctionCalls.begin(), FunctionCalls.end()),
316 FunctionCalls.end());
318 DEBUG(if (NumFns != FunctionCalls.size())
319 std::cerr << "Merged " << (NumFns-FunctionCalls.size())
320 << " call nodes in " << Func.getName() << "\n";);
324 // markAlive - Simple graph traverser that recursively walks the graph marking
325 // stuff to be alive.
327 static void markAlive(DSNode *N, std::set<DSNode*> &Alive) {
328 if (N == 0 || Alive.count(N)) return;
331 for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i)
332 markAlive(N->getLink(i), Alive);
336 // removeDeadNodes - Use a more powerful reachability analysis to eliminate
337 // subgraphs that are unreachable. This often occurs because the data
338 // structure doesn't "escape" into it's caller, and thus should be eliminated
339 // from the caller's graph entirely. This is only appropriate to use when
342 void DSGraph::removeDeadNodes() {
343 // Reduce the amount of work we have to do...
344 removeTriviallyDeadNodes();
346 // FIXME: Merge nontrivially identical call nodes...
348 // Alive - a set that holds all nodes found to be reachable/alive.
349 std::set<DSNode*> Alive;
351 // Mark all nodes reachable by call nodes as alive...
352 for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i)
353 for (unsigned j = 0, e = FunctionCalls[i].size(); j != e; ++j)
354 markAlive(FunctionCalls[i][j], Alive);
356 for (unsigned i = 0, e = OrigFunctionCalls.size(); i != e; ++i)
357 for (unsigned j = 0, e = OrigFunctionCalls[i].size(); j != e; ++j)
358 markAlive(OrigFunctionCalls[i][j], Alive);
360 // Mark all nodes reachable by scalar, global, or incomplete nodes as
362 for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
363 if (Nodes[i]->NodeType & (DSNode::ScalarNode | DSNode::GlobalNode))
364 markAlive(Nodes[i], Alive);
366 // Loop over all unreachable nodes, dropping their references...
367 std::vector<DSNode*> DeadNodes;
368 DeadNodes.reserve(Nodes.size()); // Only one allocation is allowed.
369 for (unsigned i = 0; i != Nodes.size(); ++i)
370 if (!Alive.count(Nodes[i])) {
371 DSNode *N = Nodes[i];
372 Nodes.erase(Nodes.begin()+i--); // Erase node from alive list.
373 DeadNodes.push_back(N); // Add node to our list of dead nodes
374 N->dropAllReferences(); // Drop all outgoing edges
377 // The return value is alive as well...
378 markAlive(RetNode, Alive);
380 // Delete all dead nodes...
381 std::for_each(DeadNodes.begin(), DeadNodes.end(), deleter<DSNode>);
386 // maskNodeTypes - Apply a mask to all of the node types in the graph. This
387 // is useful for clearing out markers like Scalar or Incomplete.
389 void DSGraph::maskNodeTypes(unsigned char Mask) {
390 for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
391 Nodes[i]->NodeType &= Mask;
395 //===----------------------------------------------------------------------===//
396 // LocalDataStructures Implementation
397 //===----------------------------------------------------------------------===//
399 // releaseMemory - If the pass pipeline is done with this pass, we can release
400 // our memory... here...
402 void LocalDataStructures::releaseMemory() {
403 for (std::map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
404 E = DSInfo.end(); I != E; ++I)
407 // Empty map so next time memory is released, data structures are not
412 bool LocalDataStructures::run(Module &M) {
413 // Calculate all of the graphs...
414 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
415 if (!I->isExternal())
416 DSInfo.insert(std::make_pair(&*I, new DSGraph(*I)));