1 //===- Local.cpp - Compute a local data structure graph for a function ----===//
3 // Compute the local version of the data structure graph for a function. The
4 // external interface to this file is the DSGraph constructor.
6 //===----------------------------------------------------------------------===//
8 #include "llvm/Analysis/DataStructure.h"
9 #include "llvm/Analysis/DSGraph.h"
10 #include "llvm/iMemory.h"
11 #include "llvm/iTerminators.h"
12 #include "llvm/iPHINode.h"
13 #include "llvm/iOther.h"
14 #include "llvm/Constants.h"
15 #include "llvm/DerivedTypes.h"
16 #include "llvm/Function.h"
17 #include "llvm/GlobalVariable.h"
18 #include "llvm/Support/InstVisitor.h"
19 #include "llvm/Target/TargetData.h"
20 #include "Support/Statistic.h"
21 #include "Support/Timer.h"
22 #include "Support/CommandLine.h"
24 // FIXME: This should eventually be a FunctionPass that is automatically
25 // aggregated into a Pass.
27 #include "llvm/Module.h"
29 static RegisterAnalysis<LocalDataStructures>
30 X("datastructure", "Local Data Structure Analysis");
33 // FIXME: Do something smarter with target data!
34 TargetData TD("temp-td");
36 // isPointerType - Return true if this type is big enough to hold a pointer.
37 bool isPointerType(const Type *Ty) {
38 if (isa<PointerType>(Ty))
40 else if (Ty->isPrimitiveType() && Ty->isInteger())
41 return Ty->getPrimitiveSize() >= PointerSize;
50 DisableDirectCallOpt("disable-direct-call-dsopt", cl::Hidden,
51 cl::desc("Disable direct call optimization in "
52 "DSGraph construction"));
54 DisableFieldSensitivity("disable-ds-field-sensitivity", cl::Hidden,
55 cl::desc("Disable field sensitivity in DSGraphs"));
57 //===--------------------------------------------------------------------===//
59 //===--------------------------------------------------------------------===//
61 /// This class is the builder class that constructs the local data structure
62 /// graph by performing a single pass over the function in question.
64 class GraphBuilder : InstVisitor<GraphBuilder> {
66 std::vector<DSNode*> &Nodes;
67 DSNodeHandle &RetNode; // Node that gets returned...
68 hash_map<Value*, DSNodeHandle> &ScalarMap;
69 std::vector<DSCallSite> &FunctionCalls;
72 GraphBuilder(DSGraph &g, std::vector<DSNode*> &nodes, DSNodeHandle &retNode,
73 hash_map<Value*, DSNodeHandle> &SM,
74 std::vector<DSCallSite> &fc)
75 : G(g), Nodes(nodes), RetNode(retNode), ScalarMap(SM), FunctionCalls(fc) {
77 // Create scalar nodes for all pointer arguments...
78 for (Function::aiterator I = G.getFunction().abegin(),
79 E = G.getFunction().aend(); I != E; ++I)
80 if (isPointerType(I->getType()))
83 visit(G.getFunction()); // Single pass over the function
87 // Visitor functions, used to handle each instruction type we encounter...
88 friend class InstVisitor<GraphBuilder>;
89 void visitMallocInst(MallocInst &MI) { handleAlloc(MI, DSNode::HeapNode); }
90 void visitAllocaInst(AllocaInst &AI) { handleAlloc(AI, DSNode::AllocaNode);}
91 void handleAlloc(AllocationInst &AI, DSNode::NodeTy NT);
93 void visitPHINode(PHINode &PN);
95 void visitGetElementPtrInst(User &GEP);
96 void visitReturnInst(ReturnInst &RI);
97 void visitLoadInst(LoadInst &LI);
98 void visitStoreInst(StoreInst &SI);
99 void visitCallInst(CallInst &CI);
100 void visitSetCondInst(SetCondInst &SCI) {} // SetEQ & friends are ignored
101 void visitFreeInst(FreeInst &FI);
102 void visitCastInst(CastInst &CI);
103 void visitInstruction(Instruction &I);
106 // Helper functions used to implement the visitation functions...
108 /// createNode - Create a new DSNode, ensuring that it is properly added to
111 DSNode *createNode(DSNode::NodeTy NodeType, const Type *Ty = 0) {
112 DSNode *N = new DSNode(NodeType, Ty, &G); // Create the node
113 if (DisableFieldSensitivity)
114 N->foldNodeCompletely();
118 /// setDestTo - Set the ScalarMap entry for the specified value to point to
119 /// the specified destination. If the Value already points to a node, make
120 /// sure to merge the two destinations together.
122 void setDestTo(Value &V, const DSNodeHandle &NH);
124 /// getValueDest - Return the DSNode that the actual value points to.
126 DSNodeHandle getValueDest(Value &V);
128 /// getLink - This method is used to return the specified link in the
129 /// specified node if one exists. If a link does not already exist (it's
130 /// null), then we create a new node, link it, then return it.
132 DSNodeHandle &getLink(const DSNodeHandle &Node, unsigned Link = 0);
136 //===----------------------------------------------------------------------===//
137 // DSGraph constructor - Simply use the GraphBuilder to construct the local
139 DSGraph::DSGraph(Function &F, DSGraph *GG) : Func(&F), GlobalsGraph(GG) {
140 PrintAuxCalls = false;
141 // Use the graph builder to construct the local version of the graph
142 GraphBuilder B(*this, Nodes, RetNode, ScalarMap, FunctionCalls);
144 Timer::addPeakMemoryMeasurement();
146 markIncompleteNodes(DSGraph::MarkFormalArgs);
148 // Remove any nodes made dead due to merging...
149 removeDeadNodes(DSGraph::KeepUnreachableGlobals);
153 //===----------------------------------------------------------------------===//
154 // Helper method implementations...
157 /// getValueDest - Return the DSNode that the actual value points to.
159 DSNodeHandle GraphBuilder::getValueDest(Value &Val) {
161 if (V == Constant::getNullValue(V->getType()))
162 return 0; // Null doesn't point to anything, don't add to ScalarMap!
164 DSNodeHandle &NH = ScalarMap[V];
166 return NH; // Already have a node? Just return it...
168 // Otherwise we need to create a new node to point to.
169 // Check first for constant expressions that must be traversed to
170 // extract the actual value.
171 if (Constant *C = dyn_cast<Constant>(V))
172 if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(C)) {
173 return NH = getValueDest(*CPR->getValue());
174 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
175 if (CE->getOpcode() == Instruction::Cast)
176 NH = getValueDest(*CE->getOperand(0));
177 else if (CE->getOpcode() == Instruction::GetElementPtr) {
178 visitGetElementPtrInst(*CE);
179 hash_map<Value*, DSNodeHandle>::iterator I = ScalarMap.find(CE);
180 assert(I != ScalarMap.end() && "GEP didn't get processed right?");
183 // This returns a conservative unknown node for any unhandled ConstExpr
184 return NH = createNode(DSNode::UnknownNode);
186 if (NH.getNode() == 0) { // (getelementptr null, X) returns null
192 } else if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(C)) {
193 // Random constants are unknown mem
194 return NH = createNode(DSNode::UnknownNode);
196 assert(0 && "Unknown constant type!");
199 // Otherwise we need to create a new node to point to...
201 if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
202 // Create a new global node for this global variable...
203 N = createNode(DSNode::GlobalNode, GV->getType()->getElementType());
206 // Otherwise just create a shadow node
207 N = createNode(DSNode::ShadowNode);
210 NH.setNode(N); // Remember that we are pointing to it...
216 /// getLink - This method is used to return the specified link in the
217 /// specified node if one exists. If a link does not already exist (it's
218 /// null), then we create a new node, link it, then return it. We must
219 /// specify the type of the Node field we are accessing so that we know what
220 /// type should be linked to if we need to create a new node.
222 DSNodeHandle &GraphBuilder::getLink(const DSNodeHandle &node, unsigned LinkNo) {
223 DSNodeHandle &Node = const_cast<DSNodeHandle&>(node);
224 DSNodeHandle &Link = Node.getLink(LinkNo);
225 if (!Link.getNode()) {
226 // If the link hasn't been created yet, make and return a new shadow node
227 Link = createNode(DSNode::ShadowNode);
233 /// setDestTo - Set the ScalarMap entry for the specified value to point to the
234 /// specified destination. If the Value already points to a node, make sure to
235 /// merge the two destinations together.
237 void GraphBuilder::setDestTo(Value &V, const DSNodeHandle &NH) {
238 DSNodeHandle &AINH = ScalarMap[&V];
239 if (AINH.getNode() == 0) // Not pointing to anything yet?
240 AINH = NH; // Just point directly to NH
246 //===----------------------------------------------------------------------===//
247 // Specific instruction type handler implementations...
250 /// Alloca & Malloc instruction implementation - Simply create a new memory
251 /// object, pointing the scalar to it.
253 void GraphBuilder::handleAlloc(AllocationInst &AI, DSNode::NodeTy NodeType) {
254 setDestTo(AI, createNode(NodeType));
257 // PHINode - Make the scalar for the PHI node point to all of the things the
258 // incoming values point to... which effectively causes them to be merged.
260 void GraphBuilder::visitPHINode(PHINode &PN) {
261 if (!isPointerType(PN.getType())) return; // Only pointer PHIs
263 DSNodeHandle &PNDest = ScalarMap[&PN];
264 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
265 PNDest.mergeWith(getValueDest(*PN.getIncomingValue(i)));
268 void GraphBuilder::visitGetElementPtrInst(User &GEP) {
269 DSNodeHandle Value = getValueDest(*GEP.getOperand(0));
270 if (Value.getNode() == 0) return;
273 const PointerType *PTy = cast<PointerType>(GEP.getOperand(0)->getType());
274 const Type *CurTy = PTy->getElementType();
276 if (Value.getNode()->mergeTypeInfo(CurTy, Value.getOffset())) {
277 // If the node had to be folded... exit quickly
278 setDestTo(GEP, Value); // GEP result points to folded node
283 // Handle the pointer index specially...
284 if (GEP.getNumOperands() > 1 &&
285 GEP.getOperand(1) != ConstantSInt::getNullValue(Type::LongTy)) {
287 // If we already know this is an array being accessed, don't do anything...
288 if (!TopTypeRec.isArray) {
289 TopTypeRec.isArray = true;
291 // If we are treating some inner field pointer as an array, fold the node
292 // up because we cannot handle it right. This can come because of
293 // something like this: &((&Pt->X)[1]) == &Pt->Y
295 if (Value.getOffset()) {
296 // Value is now the pointer we want to GEP to be...
297 Value.getNode()->foldNodeCompletely();
298 setDestTo(GEP, Value); // GEP result points to folded node
301 // This is a pointer to the first byte of the node. Make sure that we
302 // are pointing to the outter most type in the node.
303 // FIXME: We need to check one more case here...
309 // All of these subscripts are indexing INTO the elements we have...
310 for (unsigned i = 2, e = GEP.getNumOperands(); i < e; ++i)
311 if (GEP.getOperand(i)->getType() == Type::LongTy) {
312 // Get the type indexing into...
313 const SequentialType *STy = cast<SequentialType>(CurTy);
314 CurTy = STy->getElementType();
316 if (ConstantSInt *CS = dyn_cast<ConstantSInt>(GEP.getOperand(i))) {
317 Offset += CS->getValue()*TD.getTypeSize(CurTy);
319 // Variable index into a node. We must merge all of the elements of the
320 // sequential type here.
321 if (isa<PointerType>(STy))
322 std::cerr << "Pointer indexing not handled yet!\n";
324 const ArrayType *ATy = cast<ArrayType>(STy);
325 unsigned ElSize = TD.getTypeSize(CurTy);
326 DSNode *N = Value.getNode();
327 assert(N && "Value must have a node!");
328 unsigned RawOffset = Offset+Value.getOffset();
330 // Loop over all of the elements of the array, merging them into the
332 for (unsigned i = 1, e = ATy->getNumElements(); i != e; ++i)
333 // Merge all of the byte components of this array element
334 for (unsigned j = 0; j != ElSize; ++j)
335 N->mergeIndexes(RawOffset+j, RawOffset+i*ElSize+j);
339 } else if (GEP.getOperand(i)->getType() == Type::UByteTy) {
340 unsigned FieldNo = cast<ConstantUInt>(GEP.getOperand(i))->getValue();
341 const StructType *STy = cast<StructType>(CurTy);
342 Offset += TD.getStructLayout(STy)->MemberOffsets[FieldNo];
343 CurTy = STy->getContainedType(FieldNo);
346 // Add in the offset calculated...
347 Value.setOffset(Value.getOffset()+Offset);
349 // Value is now the pointer we want to GEP to be...
350 setDestTo(GEP, Value);
353 void GraphBuilder::visitLoadInst(LoadInst &LI) {
354 DSNodeHandle Ptr = getValueDest(*LI.getOperand(0));
355 if (Ptr.getNode() == 0) return;
357 // Make that the node is read from...
358 Ptr.getNode()->NodeType |= DSNode::Read;
360 // Ensure a typerecord exists...
361 Ptr.getNode()->mergeTypeInfo(LI.getType(), Ptr.getOffset());
363 if (isPointerType(LI.getType()))
364 setDestTo(LI, getLink(Ptr));
367 void GraphBuilder::visitStoreInst(StoreInst &SI) {
368 const Type *StoredTy = SI.getOperand(0)->getType();
369 DSNodeHandle Dest = getValueDest(*SI.getOperand(1));
370 if (Dest.getNode() == 0) return;
372 // Mark that the node is written to...
373 Dest.getNode()->NodeType |= DSNode::Modified;
375 // Ensure a typerecord exists...
376 Dest.getNode()->mergeTypeInfo(StoredTy, Dest.getOffset());
378 // Avoid adding edges from null, or processing non-"pointer" stores
379 if (isPointerType(StoredTy))
380 Dest.addEdgeTo(getValueDest(*SI.getOperand(0)));
383 void GraphBuilder::visitReturnInst(ReturnInst &RI) {
384 if (RI.getNumOperands() && isPointerType(RI.getOperand(0)->getType()))
385 RetNode.mergeWith(getValueDest(*RI.getOperand(0)));
388 void GraphBuilder::visitCallInst(CallInst &CI) {
389 // Set up the return value...
391 if (isPointerType(CI.getType()))
392 RetVal = getValueDest(CI);
395 if (DisableDirectCallOpt || !isa<Function>(CI.getOperand(0)))
396 Callee = getValueDest(*CI.getOperand(0)).getNode();
398 std::vector<DSNodeHandle> Args;
399 Args.reserve(CI.getNumOperands()-1);
401 // Calculate the arguments vector...
402 for (unsigned i = 1, e = CI.getNumOperands(); i != e; ++i)
403 if (isPointerType(CI.getOperand(i)->getType()))
404 Args.push_back(getValueDest(*CI.getOperand(i)));
406 // Add a new function call entry...
408 FunctionCalls.push_back(DSCallSite(CI, RetVal, Callee, Args));
410 FunctionCalls.push_back(DSCallSite(CI, RetVal,
411 cast<Function>(CI.getOperand(0)), Args));
414 void GraphBuilder::visitFreeInst(FreeInst &FI) {
415 // Mark that the node is written to...
416 getValueDest(*FI.getOperand(0)).getNode()->NodeType
417 |= DSNode::Modified | DSNode::HeapNode;
421 void GraphBuilder::visitCastInst(CastInst &CI) {
422 if (isPointerType(CI.getType()))
423 if (isPointerType(CI.getOperand(0)->getType())) {
424 // Cast one pointer to the other, just act like a copy instruction
425 setDestTo(CI, getValueDest(*CI.getOperand(0)));
427 // Cast something (floating point, small integer) to a pointer. We need
428 // to track the fact that the node points to SOMETHING, just something we
429 // don't know about. Make an "Unknown" node.
431 setDestTo(CI, createNode(DSNode::UnknownNode));
436 // visitInstruction - For all other instruction types, if we have any arguments
437 // that are of pointer type, make them have unknown composition bits, and merge
438 // the nodes together.
439 void GraphBuilder::visitInstruction(Instruction &Inst) {
440 DSNodeHandle CurNode;
441 if (isPointerType(Inst.getType()))
442 CurNode = getValueDest(Inst);
443 for (User::op_iterator I = Inst.op_begin(), E = Inst.op_end(); I != E; ++I)
444 if (isPointerType((*I)->getType()))
445 CurNode.mergeWith(getValueDest(**I));
447 if (CurNode.getNode())
448 CurNode.getNode()->NodeType |= DSNode::UnknownNode;
453 //===----------------------------------------------------------------------===//
454 // LocalDataStructures Implementation
455 //===----------------------------------------------------------------------===//
457 bool LocalDataStructures::run(Module &M) {
458 GlobalsGraph = new DSGraph();
460 // Calculate all of the graphs...
461 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
462 if (!I->isExternal())
463 DSInfo.insert(std::make_pair(I, new DSGraph(*I, GlobalsGraph)));
467 // releaseMemory - If the pass pipeline is done with this pass, we can release
468 // our memory... here...
470 void LocalDataStructures::releaseMemory() {
471 for (hash_map<const Function*, DSGraph*>::iterator I = DSInfo.begin(),
472 E = DSInfo.end(); I != E; ++I)
475 // Empty map so next time memory is released, data structures are not