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/Constants.h"
11 #include "llvm/DerivedTypes.h"
12 #include "llvm/Function.h"
13 #include "llvm/GlobalVariable.h"
14 #include "llvm/Instructions.h"
15 #include "llvm/Support/InstVisitor.h"
16 #include "llvm/Target/TargetData.h"
17 #include "Support/CommandLine.h"
18 #include "Support/Debug.h"
19 #include "Support/Timer.h"
21 // FIXME: This should eventually be a FunctionPass that is automatically
22 // aggregated into a Pass.
24 #include "llvm/Module.h"
26 static RegisterAnalysis<LocalDataStructures>
27 X("datastructure", "Local Data Structure Analysis");
30 // FIXME: Do something smarter with target data!
31 TargetData TD("temp-td");
33 // isPointerType - Return true if this type is big enough to hold a pointer.
34 bool isPointerType(const Type *Ty) {
35 if (isa<PointerType>(Ty))
37 else if (Ty->isPrimitiveType() && Ty->isInteger())
38 return Ty->getPrimitiveSize() >= PointerSize;
47 DisableDirectCallOpt("disable-direct-call-dsopt", cl::Hidden,
48 cl::desc("Disable direct call optimization in "
49 "DSGraph construction"));
51 DisableFieldSensitivity("disable-ds-field-sensitivity", cl::Hidden,
52 cl::desc("Disable field sensitivity in DSGraphs"));
54 //===--------------------------------------------------------------------===//
56 //===--------------------------------------------------------------------===//
58 /// This class is the builder class that constructs the local data structure
59 /// graph by performing a single pass over the function in question.
61 class GraphBuilder : InstVisitor<GraphBuilder> {
64 DSNodeHandle &RetNode; // Node that gets returned...
65 DSGraph::ScalarMapTy &ScalarMap;
66 std::vector<DSCallSite> &FunctionCalls;
69 GraphBuilder(Function &f, DSGraph &g, DSNodeHandle &retNode,
70 DSGraph::ScalarMapTy &SM, std::vector<DSCallSite> &fc)
71 : F(f), G(g), RetNode(retNode), ScalarMap(SM),
74 // Create scalar nodes for all pointer arguments...
75 for (Function::aiterator I = F.abegin(), E = F.aend(); I != E; ++I)
76 if (isPointerType(I->getType()))
79 visit(F); // Single pass over the function
83 // Visitor functions, used to handle each instruction type we encounter...
84 friend class InstVisitor<GraphBuilder>;
85 void visitMallocInst(MallocInst &MI) { handleAlloc(MI, true); }
86 void visitAllocaInst(AllocaInst &AI) { handleAlloc(AI, false); }
87 void handleAlloc(AllocationInst &AI, bool isHeap);
89 void visitPHINode(PHINode &PN);
91 void visitGetElementPtrInst(User &GEP);
92 void visitReturnInst(ReturnInst &RI);
93 void visitLoadInst(LoadInst &LI);
94 void visitStoreInst(StoreInst &SI);
95 void visitCallInst(CallInst &CI);
96 void visitInvokeInst(InvokeInst &II);
97 void visitSetCondInst(SetCondInst &SCI) {} // SetEQ & friends are ignored
98 void visitFreeInst(FreeInst &FI);
99 void visitCastInst(CastInst &CI);
100 void visitInstruction(Instruction &I);
102 void visitCallSite(CallSite CS);
104 // Helper functions used to implement the visitation functions...
106 /// createNode - Create a new DSNode, ensuring that it is properly added to
109 DSNode *createNode(const Type *Ty = 0) {
110 DSNode *N = new DSNode(Ty, &G); // Create the node
111 if (DisableFieldSensitivity) {
112 N->foldNodeCompletely();
113 if (DSNode *FN = N->getForwardNode())
119 /// setDestTo - Set the ScalarMap entry for the specified value to point to
120 /// the specified destination. If the Value already points to a node, make
121 /// sure to merge the two destinations together.
123 void setDestTo(Value &V, const DSNodeHandle &NH);
125 /// getValueDest - Return the DSNode that the actual value points to.
127 DSNodeHandle getValueDest(Value &V);
129 /// getLink - This method is used to return the specified link in the
130 /// specified node if one exists. If a link does not already exist (it's
131 /// null), then we create a new node, link it, then return it.
133 DSNodeHandle &getLink(const DSNodeHandle &Node, unsigned Link = 0);
137 //===----------------------------------------------------------------------===//
138 // DSGraph constructor - Simply use the GraphBuilder to construct the local
140 DSGraph::DSGraph(Function &F, DSGraph *GG) : GlobalsGraph(GG) {
141 PrintAuxCalls = false;
143 DEBUG(std::cerr << " [Loc] Calculating graph for: " << F.getName() << "\n");
145 // Use the graph builder to construct the local version of the graph
146 GraphBuilder B(F, *this, ReturnNodes[&F], ScalarMap, FunctionCalls);
148 Timer::addPeakMemoryMeasurement();
151 // Remove all integral constants from the scalarmap!
152 for (ScalarMapTy::iterator I = ScalarMap.begin(); I != ScalarMap.end();)
153 if (isa<ConstantIntegral>(I->first)) {
154 ScalarMapTy::iterator J = I++;
159 markIncompleteNodes(DSGraph::MarkFormalArgs);
161 // Remove any nodes made dead due to merging...
162 removeDeadNodes(DSGraph::KeepUnreachableGlobals);
166 //===----------------------------------------------------------------------===//
167 // Helper method implementations...
170 /// getValueDest - Return the DSNode that the actual value points to.
172 DSNodeHandle GraphBuilder::getValueDest(Value &Val) {
174 if (V == Constant::getNullValue(V->getType()))
175 return 0; // Null doesn't point to anything, don't add to ScalarMap!
177 DSNodeHandle &NH = ScalarMap[V];
179 return NH; // Already have a node? Just return it...
181 // Otherwise we need to create a new node to point to.
182 // Check first for constant expressions that must be traversed to
183 // extract the actual value.
184 if (Constant *C = dyn_cast<Constant>(V))
185 if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(C)) {
186 return NH = getValueDest(*CPR->getValue());
187 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
188 if (CE->getOpcode() == Instruction::Cast)
189 NH = getValueDest(*CE->getOperand(0));
190 else if (CE->getOpcode() == Instruction::GetElementPtr) {
191 visitGetElementPtrInst(*CE);
192 DSGraph::ScalarMapTy::iterator I = ScalarMap.find(CE);
193 assert(I != ScalarMap.end() && "GEP didn't get processed right?");
196 // This returns a conservative unknown node for any unhandled ConstExpr
197 return NH = createNode()->setUnknownNodeMarker();
199 if (NH.getNode() == 0) { // (getelementptr null, X) returns null
205 } else if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(C)) {
206 // Random constants are unknown mem
207 return NH = createNode()->setUnknownNodeMarker();
209 assert(0 && "Unknown constant type!");
212 // Otherwise we need to create a new node to point to...
214 if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
215 // Create a new global node for this global variable...
216 N = createNode(GV->getType()->getElementType());
219 // Otherwise just create a shadow node
223 NH.setNode(N); // Remember that we are pointing to it...
229 /// getLink - This method is used to return the specified link in the
230 /// specified node if one exists. If a link does not already exist (it's
231 /// null), then we create a new node, link it, then return it. We must
232 /// specify the type of the Node field we are accessing so that we know what
233 /// type should be linked to if we need to create a new node.
235 DSNodeHandle &GraphBuilder::getLink(const DSNodeHandle &node, unsigned LinkNo) {
236 DSNodeHandle &Node = const_cast<DSNodeHandle&>(node);
237 DSNodeHandle &Link = Node.getLink(LinkNo);
238 if (!Link.getNode()) {
239 // If the link hasn't been created yet, make and return a new shadow node
246 /// setDestTo - Set the ScalarMap entry for the specified value to point to the
247 /// specified destination. If the Value already points to a node, make sure to
248 /// merge the two destinations together.
250 void GraphBuilder::setDestTo(Value &V, const DSNodeHandle &NH) {
251 DSNodeHandle &AINH = ScalarMap[&V];
252 if (AINH.getNode() == 0) // Not pointing to anything yet?
253 AINH = NH; // Just point directly to NH
259 //===----------------------------------------------------------------------===//
260 // Specific instruction type handler implementations...
263 /// Alloca & Malloc instruction implementation - Simply create a new memory
264 /// object, pointing the scalar to it.
266 void GraphBuilder::handleAlloc(AllocationInst &AI, bool isHeap) {
267 DSNode *N = createNode();
269 N->setHeapNodeMarker();
271 N->setAllocaNodeMarker();
275 // PHINode - Make the scalar for the PHI node point to all of the things the
276 // incoming values point to... which effectively causes them to be merged.
278 void GraphBuilder::visitPHINode(PHINode &PN) {
279 if (!isPointerType(PN.getType())) return; // Only pointer PHIs
281 DSNodeHandle &PNDest = ScalarMap[&PN];
282 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
283 PNDest.mergeWith(getValueDest(*PN.getIncomingValue(i)));
286 void GraphBuilder::visitGetElementPtrInst(User &GEP) {
287 DSNodeHandle Value = getValueDest(*GEP.getOperand(0));
288 if (Value.getNode() == 0) return;
291 const PointerType *PTy = cast<PointerType>(GEP.getOperand(0)->getType());
292 const Type *CurTy = PTy->getElementType();
294 if (Value.getNode()->mergeTypeInfo(CurTy, Value.getOffset())) {
295 // If the node had to be folded... exit quickly
296 setDestTo(GEP, Value); // GEP result points to folded node
301 // Handle the pointer index specially...
302 if (GEP.getNumOperands() > 1 &&
303 GEP.getOperand(1) != ConstantSInt::getNullValue(Type::LongTy)) {
305 // If we already know this is an array being accessed, don't do anything...
306 if (!TopTypeRec.isArray) {
307 TopTypeRec.isArray = true;
309 // If we are treating some inner field pointer as an array, fold the node
310 // up because we cannot handle it right. This can come because of
311 // something like this: &((&Pt->X)[1]) == &Pt->Y
313 if (Value.getOffset()) {
314 // Value is now the pointer we want to GEP to be...
315 Value.getNode()->foldNodeCompletely();
316 setDestTo(GEP, Value); // GEP result points to folded node
319 // This is a pointer to the first byte of the node. Make sure that we
320 // are pointing to the outter most type in the node.
321 // FIXME: We need to check one more case here...
327 // All of these subscripts are indexing INTO the elements we have...
328 for (unsigned i = 2, e = GEP.getNumOperands(); i < e; ++i)
329 if (GEP.getOperand(i)->getType() == Type::LongTy) {
330 // Get the type indexing into...
331 const SequentialType *STy = cast<SequentialType>(CurTy);
332 CurTy = STy->getElementType();
334 if (ConstantSInt *CS = dyn_cast<ConstantSInt>(GEP.getOperand(i))) {
335 Offset += CS->getValue()*TD.getTypeSize(CurTy);
337 // Variable index into a node. We must merge all of the elements of the
338 // sequential type here.
339 if (isa<PointerType>(STy))
340 std::cerr << "Pointer indexing not handled yet!\n";
342 const ArrayType *ATy = cast<ArrayType>(STy);
343 unsigned ElSize = TD.getTypeSize(CurTy);
344 DSNode *N = Value.getNode();
345 assert(N && "Value must have a node!");
346 unsigned RawOffset = Offset+Value.getOffset();
348 // Loop over all of the elements of the array, merging them into the
350 for (unsigned i = 1, e = ATy->getNumElements(); i != e; ++i)
351 // Merge all of the byte components of this array element
352 for (unsigned j = 0; j != ElSize; ++j)
353 N->mergeIndexes(RawOffset+j, RawOffset+i*ElSize+j);
357 } else if (GEP.getOperand(i)->getType() == Type::UByteTy) {
358 unsigned FieldNo = cast<ConstantUInt>(GEP.getOperand(i))->getValue();
359 const StructType *STy = cast<StructType>(CurTy);
360 Offset += TD.getStructLayout(STy)->MemberOffsets[FieldNo];
361 CurTy = STy->getContainedType(FieldNo);
364 // Add in the offset calculated...
365 Value.setOffset(Value.getOffset()+Offset);
367 // Value is now the pointer we want to GEP to be...
368 setDestTo(GEP, Value);
371 void GraphBuilder::visitLoadInst(LoadInst &LI) {
372 DSNodeHandle Ptr = getValueDest(*LI.getOperand(0));
373 if (Ptr.getNode() == 0) return;
375 // Make that the node is read from...
376 Ptr.getNode()->setReadMarker();
378 // Ensure a typerecord exists...
379 Ptr.getNode()->mergeTypeInfo(LI.getType(), Ptr.getOffset(), false);
381 if (isPointerType(LI.getType()))
382 setDestTo(LI, getLink(Ptr));
385 void GraphBuilder::visitStoreInst(StoreInst &SI) {
386 const Type *StoredTy = SI.getOperand(0)->getType();
387 DSNodeHandle Dest = getValueDest(*SI.getOperand(1));
388 if (Dest.getNode() == 0) return;
390 // Mark that the node is written to...
391 Dest.getNode()->setModifiedMarker();
393 // Ensure a typerecord exists...
394 Dest.getNode()->mergeTypeInfo(StoredTy, Dest.getOffset());
396 // Avoid adding edges from null, or processing non-"pointer" stores
397 if (isPointerType(StoredTy))
398 Dest.addEdgeTo(getValueDest(*SI.getOperand(0)));
401 void GraphBuilder::visitReturnInst(ReturnInst &RI) {
402 if (RI.getNumOperands() && isPointerType(RI.getOperand(0)->getType()))
403 RetNode.mergeWith(getValueDest(*RI.getOperand(0)));
406 void GraphBuilder::visitCallInst(CallInst &CI) {
410 void GraphBuilder::visitInvokeInst(InvokeInst &II) {
414 void GraphBuilder::visitCallSite(CallSite CS) {
415 // Special case handling of certain libc allocation functions here.
416 if (Function *F = CS.getCalledFunction())
418 if (F->getName() == "calloc") {
419 setDestTo(*CS.getInstruction(),
420 createNode()->setHeapNodeMarker()->setModifiedMarker());
422 } else if (F->getName() == "realloc") {
423 DSNodeHandle RetNH = getValueDest(*CS.getInstruction());
424 RetNH.mergeWith(getValueDest(**CS.arg_begin()));
425 DSNode *N = RetNH.getNode();
426 if (N) N->setHeapNodeMarker()->setModifiedMarker()->setReadMarker();
431 // Set up the return value...
433 Instruction *I = CS.getInstruction();
434 if (isPointerType(I->getType()))
435 RetVal = getValueDest(*I);
438 if (DisableDirectCallOpt || !isa<Function>(CS.getCalledValue()))
439 Callee = getValueDest(*CS.getCalledValue()).getNode();
441 std::vector<DSNodeHandle> Args;
442 Args.reserve(CS.arg_end()-CS.arg_begin());
444 // Calculate the arguments vector...
445 for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); I != E; ++I)
446 if (isPointerType((*I)->getType()))
447 Args.push_back(getValueDest(**I));
449 // Add a new function call entry...
451 FunctionCalls.push_back(DSCallSite(CS, RetVal, Callee, Args));
453 FunctionCalls.push_back(DSCallSite(CS, RetVal, CS.getCalledFunction(),
457 void GraphBuilder::visitFreeInst(FreeInst &FI) {
458 // Mark that the node is written to...
459 DSNode *N = getValueDest(*FI.getOperand(0)).getNode();
460 N->setModifiedMarker();
461 N->setHeapNodeMarker();
465 void GraphBuilder::visitCastInst(CastInst &CI) {
466 if (isPointerType(CI.getType()))
467 if (isPointerType(CI.getOperand(0)->getType())) {
468 // Cast one pointer to the other, just act like a copy instruction
469 setDestTo(CI, getValueDest(*CI.getOperand(0)));
471 // Cast something (floating point, small integer) to a pointer. We need
472 // to track the fact that the node points to SOMETHING, just something we
473 // don't know about. Make an "Unknown" node.
475 setDestTo(CI, createNode()->setUnknownNodeMarker());
480 // visitInstruction - For all other instruction types, if we have any arguments
481 // that are of pointer type, make them have unknown composition bits, and merge
482 // the nodes together.
483 void GraphBuilder::visitInstruction(Instruction &Inst) {
484 DSNodeHandle CurNode;
485 if (isPointerType(Inst.getType()))
486 CurNode = getValueDest(Inst);
487 for (User::op_iterator I = Inst.op_begin(), E = Inst.op_end(); I != E; ++I)
488 if (isPointerType((*I)->getType()))
489 CurNode.mergeWith(getValueDest(**I));
491 if (CurNode.getNode())
492 CurNode.getNode()->setUnknownNodeMarker();
497 //===----------------------------------------------------------------------===//
498 // LocalDataStructures Implementation
499 //===----------------------------------------------------------------------===//
501 bool LocalDataStructures::run(Module &M) {
502 GlobalsGraph = new DSGraph();
504 // Calculate all of the graphs...
505 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
506 if (!I->isExternal())
507 DSInfo.insert(std::make_pair(I, new DSGraph(*I, GlobalsGraph)));
511 // releaseMemory - If the pass pipeline is done with this pass, we can release
512 // our memory... here...
514 void LocalDataStructures::releaseMemory() {
515 for (hash_map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
516 E = DSInfo.end(); I != E; ++I) {
517 I->second->getReturnNodes().erase(I->first);
518 if (I->second->getReturnNodes().empty())
522 // Empty map so next time memory is released, data structures are not