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> {
67 std::vector<DSNode*> &Nodes;
68 DSNodeHandle &RetNode; // Node that gets returned...
69 DSGraph::ScalarMapTy &ScalarMap;
70 std::vector<DSCallSite> &FunctionCalls;
73 GraphBuilder(Function &f, DSGraph &g, std::vector<DSNode*> &nodes,
74 DSNodeHandle &retNode, DSGraph::ScalarMapTy &SM,
75 std::vector<DSCallSite> &fc)
76 : F(f), G(g), Nodes(nodes), RetNode(retNode), ScalarMap(SM),
79 // Create scalar nodes for all pointer arguments...
80 for (Function::aiterator I = F.abegin(), E = F.aend(); I != E; ++I)
81 if (isPointerType(I->getType()))
84 visit(F); // Single pass over the function
88 // Visitor functions, used to handle each instruction type we encounter...
89 friend class InstVisitor<GraphBuilder>;
90 void visitMallocInst(MallocInst &MI) { handleAlloc(MI, true); }
91 void visitAllocaInst(AllocaInst &AI) { handleAlloc(AI, false); }
92 void handleAlloc(AllocationInst &AI, bool isHeap);
94 void visitPHINode(PHINode &PN);
96 void visitGetElementPtrInst(User &GEP);
97 void visitReturnInst(ReturnInst &RI);
98 void visitLoadInst(LoadInst &LI);
99 void visitStoreInst(StoreInst &SI);
100 void visitCallInst(CallInst &CI);
101 void visitSetCondInst(SetCondInst &SCI) {} // SetEQ & friends are ignored
102 void visitFreeInst(FreeInst &FI);
103 void visitCastInst(CastInst &CI);
104 void visitInstruction(Instruction &I);
107 // Helper functions used to implement the visitation functions...
109 /// createNode - Create a new DSNode, ensuring that it is properly added to
112 DSNode *createNode(const Type *Ty = 0) {
113 DSNode *N = new DSNode(Ty, &G); // Create the node
114 if (DisableFieldSensitivity) {
115 N->foldNodeCompletely();
116 if (DSNode *FN = N->getForwardNode())
122 /// setDestTo - Set the ScalarMap entry for the specified value to point to
123 /// the specified destination. If the Value already points to a node, make
124 /// sure to merge the two destinations together.
126 void setDestTo(Value &V, const DSNodeHandle &NH);
128 /// getValueDest - Return the DSNode that the actual value points to.
130 DSNodeHandle getValueDest(Value &V);
132 /// getLink - This method is used to return the specified link in the
133 /// specified node if one exists. If a link does not already exist (it's
134 /// null), then we create a new node, link it, then return it.
136 DSNodeHandle &getLink(const DSNodeHandle &Node, unsigned Link = 0);
140 //===----------------------------------------------------------------------===//
141 // DSGraph constructor - Simply use the GraphBuilder to construct the local
143 DSGraph::DSGraph(Function &F, DSGraph *GG) : GlobalsGraph(GG) {
144 PrintAuxCalls = false;
146 DEBUG(std::cerr << " [Loc] Calculating graph for: " << F.getName() << "\n");
148 // Use the graph builder to construct the local version of the graph
149 GraphBuilder B(F, *this, Nodes, ReturnNodes[&F], ScalarMap, FunctionCalls);
151 Timer::addPeakMemoryMeasurement();
154 // Remove all integral constants from the scalarmap!
155 for (ScalarMapTy::iterator I = ScalarMap.begin(); I != ScalarMap.end();)
156 if (isa<ConstantIntegral>(I->first)) {
157 ScalarMapTy::iterator J = I++;
162 markIncompleteNodes(DSGraph::MarkFormalArgs);
164 // Remove any nodes made dead due to merging...
165 removeDeadNodes(DSGraph::KeepUnreachableGlobals);
169 //===----------------------------------------------------------------------===//
170 // Helper method implementations...
173 /// getValueDest - Return the DSNode that the actual value points to.
175 DSNodeHandle GraphBuilder::getValueDest(Value &Val) {
177 if (V == Constant::getNullValue(V->getType()))
178 return 0; // Null doesn't point to anything, don't add to ScalarMap!
180 DSNodeHandle &NH = ScalarMap[V];
182 return NH; // Already have a node? Just return it...
184 // Otherwise we need to create a new node to point to.
185 // Check first for constant expressions that must be traversed to
186 // extract the actual value.
187 if (Constant *C = dyn_cast<Constant>(V))
188 if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(C)) {
189 return NH = getValueDest(*CPR->getValue());
190 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
191 if (CE->getOpcode() == Instruction::Cast)
192 NH = getValueDest(*CE->getOperand(0));
193 else if (CE->getOpcode() == Instruction::GetElementPtr) {
194 visitGetElementPtrInst(*CE);
195 DSGraph::ScalarMapTy::iterator I = ScalarMap.find(CE);
196 assert(I != ScalarMap.end() && "GEP didn't get processed right?");
199 // This returns a conservative unknown node for any unhandled ConstExpr
200 return NH = createNode()->setUnknownNodeMarker();
202 if (NH.getNode() == 0) { // (getelementptr null, X) returns null
208 } else if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(C)) {
209 // Random constants are unknown mem
210 return NH = createNode()->setUnknownNodeMarker();
212 assert(0 && "Unknown constant type!");
215 // Otherwise we need to create a new node to point to...
217 if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
218 // Create a new global node for this global variable...
219 N = createNode(GV->getType()->getElementType());
222 // Otherwise just create a shadow node
226 NH.setNode(N); // Remember that we are pointing to it...
232 /// getLink - This method is used to return the specified link in the
233 /// specified node if one exists. If a link does not already exist (it's
234 /// null), then we create a new node, link it, then return it. We must
235 /// specify the type of the Node field we are accessing so that we know what
236 /// type should be linked to if we need to create a new node.
238 DSNodeHandle &GraphBuilder::getLink(const DSNodeHandle &node, unsigned LinkNo) {
239 DSNodeHandle &Node = const_cast<DSNodeHandle&>(node);
240 DSNodeHandle &Link = Node.getLink(LinkNo);
241 if (!Link.getNode()) {
242 // If the link hasn't been created yet, make and return a new shadow node
249 /// setDestTo - Set the ScalarMap entry for the specified value to point to the
250 /// specified destination. If the Value already points to a node, make sure to
251 /// merge the two destinations together.
253 void GraphBuilder::setDestTo(Value &V, const DSNodeHandle &NH) {
254 DSNodeHandle &AINH = ScalarMap[&V];
255 if (AINH.getNode() == 0) // Not pointing to anything yet?
256 AINH = NH; // Just point directly to NH
262 //===----------------------------------------------------------------------===//
263 // Specific instruction type handler implementations...
266 /// Alloca & Malloc instruction implementation - Simply create a new memory
267 /// object, pointing the scalar to it.
269 void GraphBuilder::handleAlloc(AllocationInst &AI, bool isHeap) {
270 DSNode *N = createNode();
272 N->setHeapNodeMarker();
274 N->setAllocaNodeMarker();
278 // PHINode - Make the scalar for the PHI node point to all of the things the
279 // incoming values point to... which effectively causes them to be merged.
281 void GraphBuilder::visitPHINode(PHINode &PN) {
282 if (!isPointerType(PN.getType())) return; // Only pointer PHIs
284 DSNodeHandle &PNDest = ScalarMap[&PN];
285 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
286 PNDest.mergeWith(getValueDest(*PN.getIncomingValue(i)));
289 void GraphBuilder::visitGetElementPtrInst(User &GEP) {
290 DSNodeHandle Value = getValueDest(*GEP.getOperand(0));
291 if (Value.getNode() == 0) return;
294 const PointerType *PTy = cast<PointerType>(GEP.getOperand(0)->getType());
295 const Type *CurTy = PTy->getElementType();
297 if (Value.getNode()->mergeTypeInfo(CurTy, Value.getOffset())) {
298 // If the node had to be folded... exit quickly
299 setDestTo(GEP, Value); // GEP result points to folded node
304 // Handle the pointer index specially...
305 if (GEP.getNumOperands() > 1 &&
306 GEP.getOperand(1) != ConstantSInt::getNullValue(Type::LongTy)) {
308 // If we already know this is an array being accessed, don't do anything...
309 if (!TopTypeRec.isArray) {
310 TopTypeRec.isArray = true;
312 // If we are treating some inner field pointer as an array, fold the node
313 // up because we cannot handle it right. This can come because of
314 // something like this: &((&Pt->X)[1]) == &Pt->Y
316 if (Value.getOffset()) {
317 // Value is now the pointer we want to GEP to be...
318 Value.getNode()->foldNodeCompletely();
319 setDestTo(GEP, Value); // GEP result points to folded node
322 // This is a pointer to the first byte of the node. Make sure that we
323 // are pointing to the outter most type in the node.
324 // FIXME: We need to check one more case here...
330 // All of these subscripts are indexing INTO the elements we have...
331 for (unsigned i = 2, e = GEP.getNumOperands(); i < e; ++i)
332 if (GEP.getOperand(i)->getType() == Type::LongTy) {
333 // Get the type indexing into...
334 const SequentialType *STy = cast<SequentialType>(CurTy);
335 CurTy = STy->getElementType();
337 if (ConstantSInt *CS = dyn_cast<ConstantSInt>(GEP.getOperand(i))) {
338 Offset += CS->getValue()*TD.getTypeSize(CurTy);
340 // Variable index into a node. We must merge all of the elements of the
341 // sequential type here.
342 if (isa<PointerType>(STy))
343 std::cerr << "Pointer indexing not handled yet!\n";
345 const ArrayType *ATy = cast<ArrayType>(STy);
346 unsigned ElSize = TD.getTypeSize(CurTy);
347 DSNode *N = Value.getNode();
348 assert(N && "Value must have a node!");
349 unsigned RawOffset = Offset+Value.getOffset();
351 // Loop over all of the elements of the array, merging them into the
353 for (unsigned i = 1, e = ATy->getNumElements(); i != e; ++i)
354 // Merge all of the byte components of this array element
355 for (unsigned j = 0; j != ElSize; ++j)
356 N->mergeIndexes(RawOffset+j, RawOffset+i*ElSize+j);
360 } else if (GEP.getOperand(i)->getType() == Type::UByteTy) {
361 unsigned FieldNo = cast<ConstantUInt>(GEP.getOperand(i))->getValue();
362 const StructType *STy = cast<StructType>(CurTy);
363 Offset += TD.getStructLayout(STy)->MemberOffsets[FieldNo];
364 CurTy = STy->getContainedType(FieldNo);
367 // Add in the offset calculated...
368 Value.setOffset(Value.getOffset()+Offset);
370 // Value is now the pointer we want to GEP to be...
371 setDestTo(GEP, Value);
374 void GraphBuilder::visitLoadInst(LoadInst &LI) {
375 DSNodeHandle Ptr = getValueDest(*LI.getOperand(0));
376 if (Ptr.getNode() == 0) return;
378 // Make that the node is read from...
379 Ptr.getNode()->setReadMarker();
381 // Ensure a typerecord exists...
382 Ptr.getNode()->mergeTypeInfo(LI.getType(), Ptr.getOffset(), false);
384 if (isPointerType(LI.getType()))
385 setDestTo(LI, getLink(Ptr));
388 void GraphBuilder::visitStoreInst(StoreInst &SI) {
389 const Type *StoredTy = SI.getOperand(0)->getType();
390 DSNodeHandle Dest = getValueDest(*SI.getOperand(1));
391 if (Dest.getNode() == 0) return;
393 // Mark that the node is written to...
394 Dest.getNode()->setModifiedMarker();
396 // Ensure a typerecord exists...
397 Dest.getNode()->mergeTypeInfo(StoredTy, Dest.getOffset());
399 // Avoid adding edges from null, or processing non-"pointer" stores
400 if (isPointerType(StoredTy))
401 Dest.addEdgeTo(getValueDest(*SI.getOperand(0)));
404 void GraphBuilder::visitReturnInst(ReturnInst &RI) {
405 if (RI.getNumOperands() && isPointerType(RI.getOperand(0)->getType()))
406 RetNode.mergeWith(getValueDest(*RI.getOperand(0)));
409 void GraphBuilder::visitCallInst(CallInst &CI) {
410 // Set up the return value...
412 if (isPointerType(CI.getType()))
413 RetVal = getValueDest(CI);
416 if (DisableDirectCallOpt || !isa<Function>(CI.getOperand(0)))
417 Callee = getValueDest(*CI.getOperand(0)).getNode();
419 std::vector<DSNodeHandle> Args;
420 Args.reserve(CI.getNumOperands()-1);
422 // Calculate the arguments vector...
423 for (unsigned i = 1, e = CI.getNumOperands(); i != e; ++i)
424 if (isPointerType(CI.getOperand(i)->getType()))
425 Args.push_back(getValueDest(*CI.getOperand(i)));
427 // Add a new function call entry...
429 FunctionCalls.push_back(DSCallSite(CI, RetVal, Callee, Args));
431 FunctionCalls.push_back(DSCallSite(CI, RetVal,
432 cast<Function>(CI.getOperand(0)), Args));
435 void GraphBuilder::visitFreeInst(FreeInst &FI) {
436 // Mark that the node is written to...
437 DSNode *N = getValueDest(*FI.getOperand(0)).getNode();
438 N->setModifiedMarker();
439 N->setHeapNodeMarker();
443 void GraphBuilder::visitCastInst(CastInst &CI) {
444 if (isPointerType(CI.getType()))
445 if (isPointerType(CI.getOperand(0)->getType())) {
446 // Cast one pointer to the other, just act like a copy instruction
447 setDestTo(CI, getValueDest(*CI.getOperand(0)));
449 // Cast something (floating point, small integer) to a pointer. We need
450 // to track the fact that the node points to SOMETHING, just something we
451 // don't know about. Make an "Unknown" node.
453 setDestTo(CI, createNode()->setUnknownNodeMarker());
458 // visitInstruction - For all other instruction types, if we have any arguments
459 // that are of pointer type, make them have unknown composition bits, and merge
460 // the nodes together.
461 void GraphBuilder::visitInstruction(Instruction &Inst) {
462 DSNodeHandle CurNode;
463 if (isPointerType(Inst.getType()))
464 CurNode = getValueDest(Inst);
465 for (User::op_iterator I = Inst.op_begin(), E = Inst.op_end(); I != E; ++I)
466 if (isPointerType((*I)->getType()))
467 CurNode.mergeWith(getValueDest(**I));
469 if (CurNode.getNode())
470 CurNode.getNode()->setUnknownNodeMarker();
475 //===----------------------------------------------------------------------===//
476 // LocalDataStructures Implementation
477 //===----------------------------------------------------------------------===//
479 bool LocalDataStructures::run(Module &M) {
480 GlobalsGraph = new DSGraph();
482 // Calculate all of the graphs...
483 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
484 if (!I->isExternal())
485 DSInfo.insert(std::make_pair(I, new DSGraph(*I, GlobalsGraph)));
489 // releaseMemory - If the pass pipeline is done with this pass, we can release
490 // our memory... here...
492 void LocalDataStructures::releaseMemory() {
493 for (hash_map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
494 E = DSInfo.end(); I != E; ++I) {
495 I->second->getReturnNodes().erase(I->first);
496 if (I->second->getReturnNodes().empty())
500 // Empty map so next time memory is released, data structures are not