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 DSNodeHandle &RetNode; // Node that gets returned...
68 DSGraph::ScalarMapTy &ScalarMap;
69 std::vector<DSCallSite> &FunctionCalls;
72 GraphBuilder(Function &f, DSGraph &g, DSNodeHandle &retNode,
73 DSGraph::ScalarMapTy &SM, std::vector<DSCallSite> &fc)
74 : F(f), G(g), RetNode(retNode), ScalarMap(SM),
77 // Create scalar nodes for all pointer arguments...
78 for (Function::aiterator I = F.abegin(), E = F.aend(); I != E; ++I)
79 if (isPointerType(I->getType()))
82 visit(F); // Single pass over the function
86 // Visitor functions, used to handle each instruction type we encounter...
87 friend class InstVisitor<GraphBuilder>;
88 void visitMallocInst(MallocInst &MI) { handleAlloc(MI, true); }
89 void visitAllocaInst(AllocaInst &AI) { handleAlloc(AI, false); }
90 void handleAlloc(AllocationInst &AI, bool isHeap);
92 void visitPHINode(PHINode &PN);
94 void visitGetElementPtrInst(User &GEP);
95 void visitReturnInst(ReturnInst &RI);
96 void visitLoadInst(LoadInst &LI);
97 void visitStoreInst(StoreInst &SI);
98 void visitCallInst(CallInst &CI);
99 void visitSetCondInst(SetCondInst &SCI) {} // SetEQ & friends are ignored
100 void visitFreeInst(FreeInst &FI);
101 void visitCastInst(CastInst &CI);
102 void visitInstruction(Instruction &I);
105 // Helper functions used to implement the visitation functions...
107 /// createNode - Create a new DSNode, ensuring that it is properly added to
110 DSNode *createNode(const Type *Ty = 0) {
111 DSNode *N = new DSNode(Ty, &G); // Create the node
112 if (DisableFieldSensitivity) {
113 N->foldNodeCompletely();
114 if (DSNode *FN = N->getForwardNode())
120 /// setDestTo - Set the ScalarMap entry for the specified value to point to
121 /// the specified destination. If the Value already points to a node, make
122 /// sure to merge the two destinations together.
124 void setDestTo(Value &V, const DSNodeHandle &NH);
126 /// getValueDest - Return the DSNode that the actual value points to.
128 DSNodeHandle getValueDest(Value &V);
130 /// getLink - This method is used to return the specified link in the
131 /// specified node if one exists. If a link does not already exist (it's
132 /// null), then we create a new node, link it, then return it.
134 DSNodeHandle &getLink(const DSNodeHandle &Node, unsigned Link = 0);
138 //===----------------------------------------------------------------------===//
139 // DSGraph constructor - Simply use the GraphBuilder to construct the local
141 DSGraph::DSGraph(Function &F, DSGraph *GG) : GlobalsGraph(GG) {
142 PrintAuxCalls = false;
144 DEBUG(std::cerr << " [Loc] Calculating graph for: " << F.getName() << "\n");
146 // Use the graph builder to construct the local version of the graph
147 GraphBuilder B(F, *this, ReturnNodes[&F], ScalarMap, FunctionCalls);
149 Timer::addPeakMemoryMeasurement();
152 // Remove all integral constants from the scalarmap!
153 for (ScalarMapTy::iterator I = ScalarMap.begin(); I != ScalarMap.end();)
154 if (isa<ConstantIntegral>(I->first)) {
155 ScalarMapTy::iterator J = I++;
160 markIncompleteNodes(DSGraph::MarkFormalArgs);
162 // Remove any nodes made dead due to merging...
163 removeDeadNodes(DSGraph::KeepUnreachableGlobals);
167 //===----------------------------------------------------------------------===//
168 // Helper method implementations...
171 /// getValueDest - Return the DSNode that the actual value points to.
173 DSNodeHandle GraphBuilder::getValueDest(Value &Val) {
175 if (V == Constant::getNullValue(V->getType()))
176 return 0; // Null doesn't point to anything, don't add to ScalarMap!
178 DSNodeHandle &NH = ScalarMap[V];
180 return NH; // Already have a node? Just return it...
182 // Otherwise we need to create a new node to point to.
183 // Check first for constant expressions that must be traversed to
184 // extract the actual value.
185 if (Constant *C = dyn_cast<Constant>(V))
186 if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(C)) {
187 return NH = getValueDest(*CPR->getValue());
188 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
189 if (CE->getOpcode() == Instruction::Cast)
190 NH = getValueDest(*CE->getOperand(0));
191 else if (CE->getOpcode() == Instruction::GetElementPtr) {
192 visitGetElementPtrInst(*CE);
193 DSGraph::ScalarMapTy::iterator I = ScalarMap.find(CE);
194 assert(I != ScalarMap.end() && "GEP didn't get processed right?");
197 // This returns a conservative unknown node for any unhandled ConstExpr
198 return NH = createNode()->setUnknownNodeMarker();
200 if (NH.getNode() == 0) { // (getelementptr null, X) returns null
206 } else if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(C)) {
207 // Random constants are unknown mem
208 return NH = createNode()->setUnknownNodeMarker();
210 assert(0 && "Unknown constant type!");
213 // Otherwise we need to create a new node to point to...
215 if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
216 // Create a new global node for this global variable...
217 N = createNode(GV->getType()->getElementType());
220 // Otherwise just create a shadow node
224 NH.setNode(N); // Remember that we are pointing to it...
230 /// getLink - This method is used to return the specified link in the
231 /// specified node if one exists. If a link does not already exist (it's
232 /// null), then we create a new node, link it, then return it. We must
233 /// specify the type of the Node field we are accessing so that we know what
234 /// type should be linked to if we need to create a new node.
236 DSNodeHandle &GraphBuilder::getLink(const DSNodeHandle &node, unsigned LinkNo) {
237 DSNodeHandle &Node = const_cast<DSNodeHandle&>(node);
238 DSNodeHandle &Link = Node.getLink(LinkNo);
239 if (!Link.getNode()) {
240 // If the link hasn't been created yet, make and return a new shadow node
247 /// setDestTo - Set the ScalarMap entry for the specified value to point to the
248 /// specified destination. If the Value already points to a node, make sure to
249 /// merge the two destinations together.
251 void GraphBuilder::setDestTo(Value &V, const DSNodeHandle &NH) {
252 DSNodeHandle &AINH = ScalarMap[&V];
253 if (AINH.getNode() == 0) // Not pointing to anything yet?
254 AINH = NH; // Just point directly to NH
260 //===----------------------------------------------------------------------===//
261 // Specific instruction type handler implementations...
264 /// Alloca & Malloc instruction implementation - Simply create a new memory
265 /// object, pointing the scalar to it.
267 void GraphBuilder::handleAlloc(AllocationInst &AI, bool isHeap) {
268 DSNode *N = createNode();
270 N->setHeapNodeMarker();
272 N->setAllocaNodeMarker();
276 // PHINode - Make the scalar for the PHI node point to all of the things the
277 // incoming values point to... which effectively causes them to be merged.
279 void GraphBuilder::visitPHINode(PHINode &PN) {
280 if (!isPointerType(PN.getType())) return; // Only pointer PHIs
282 DSNodeHandle &PNDest = ScalarMap[&PN];
283 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
284 PNDest.mergeWith(getValueDest(*PN.getIncomingValue(i)));
287 void GraphBuilder::visitGetElementPtrInst(User &GEP) {
288 DSNodeHandle Value = getValueDest(*GEP.getOperand(0));
289 if (Value.getNode() == 0) return;
292 const PointerType *PTy = cast<PointerType>(GEP.getOperand(0)->getType());
293 const Type *CurTy = PTy->getElementType();
295 if (Value.getNode()->mergeTypeInfo(CurTy, Value.getOffset())) {
296 // If the node had to be folded... exit quickly
297 setDestTo(GEP, Value); // GEP result points to folded node
302 // Handle the pointer index specially...
303 if (GEP.getNumOperands() > 1 &&
304 GEP.getOperand(1) != ConstantSInt::getNullValue(Type::LongTy)) {
306 // If we already know this is an array being accessed, don't do anything...
307 if (!TopTypeRec.isArray) {
308 TopTypeRec.isArray = true;
310 // If we are treating some inner field pointer as an array, fold the node
311 // up because we cannot handle it right. This can come because of
312 // something like this: &((&Pt->X)[1]) == &Pt->Y
314 if (Value.getOffset()) {
315 // Value is now the pointer we want to GEP to be...
316 Value.getNode()->foldNodeCompletely();
317 setDestTo(GEP, Value); // GEP result points to folded node
320 // This is a pointer to the first byte of the node. Make sure that we
321 // are pointing to the outter most type in the node.
322 // FIXME: We need to check one more case here...
328 // All of these subscripts are indexing INTO the elements we have...
329 for (unsigned i = 2, e = GEP.getNumOperands(); i < e; ++i)
330 if (GEP.getOperand(i)->getType() == Type::LongTy) {
331 // Get the type indexing into...
332 const SequentialType *STy = cast<SequentialType>(CurTy);
333 CurTy = STy->getElementType();
335 if (ConstantSInt *CS = dyn_cast<ConstantSInt>(GEP.getOperand(i))) {
336 Offset += CS->getValue()*TD.getTypeSize(CurTy);
338 // Variable index into a node. We must merge all of the elements of the
339 // sequential type here.
340 if (isa<PointerType>(STy))
341 std::cerr << "Pointer indexing not handled yet!\n";
343 const ArrayType *ATy = cast<ArrayType>(STy);
344 unsigned ElSize = TD.getTypeSize(CurTy);
345 DSNode *N = Value.getNode();
346 assert(N && "Value must have a node!");
347 unsigned RawOffset = Offset+Value.getOffset();
349 // Loop over all of the elements of the array, merging them into the
351 for (unsigned i = 1, e = ATy->getNumElements(); i != e; ++i)
352 // Merge all of the byte components of this array element
353 for (unsigned j = 0; j != ElSize; ++j)
354 N->mergeIndexes(RawOffset+j, RawOffset+i*ElSize+j);
358 } else if (GEP.getOperand(i)->getType() == Type::UByteTy) {
359 unsigned FieldNo = cast<ConstantUInt>(GEP.getOperand(i))->getValue();
360 const StructType *STy = cast<StructType>(CurTy);
361 Offset += TD.getStructLayout(STy)->MemberOffsets[FieldNo];
362 CurTy = STy->getContainedType(FieldNo);
365 // Add in the offset calculated...
366 Value.setOffset(Value.getOffset()+Offset);
368 // Value is now the pointer we want to GEP to be...
369 setDestTo(GEP, Value);
372 void GraphBuilder::visitLoadInst(LoadInst &LI) {
373 DSNodeHandle Ptr = getValueDest(*LI.getOperand(0));
374 if (Ptr.getNode() == 0) return;
376 // Make that the node is read from...
377 Ptr.getNode()->setReadMarker();
379 // Ensure a typerecord exists...
380 Ptr.getNode()->mergeTypeInfo(LI.getType(), Ptr.getOffset(), false);
382 if (isPointerType(LI.getType()))
383 setDestTo(LI, getLink(Ptr));
386 void GraphBuilder::visitStoreInst(StoreInst &SI) {
387 const Type *StoredTy = SI.getOperand(0)->getType();
388 DSNodeHandle Dest = getValueDest(*SI.getOperand(1));
389 if (Dest.getNode() == 0) return;
391 // Mark that the node is written to...
392 Dest.getNode()->setModifiedMarker();
394 // Ensure a typerecord exists...
395 Dest.getNode()->mergeTypeInfo(StoredTy, Dest.getOffset());
397 // Avoid adding edges from null, or processing non-"pointer" stores
398 if (isPointerType(StoredTy))
399 Dest.addEdgeTo(getValueDest(*SI.getOperand(0)));
402 void GraphBuilder::visitReturnInst(ReturnInst &RI) {
403 if (RI.getNumOperands() && isPointerType(RI.getOperand(0)->getType()))
404 RetNode.mergeWith(getValueDest(*RI.getOperand(0)));
407 void GraphBuilder::visitCallInst(CallInst &CI) {
408 // Set up the return value...
410 if (isPointerType(CI.getType()))
411 RetVal = getValueDest(CI);
414 if (DisableDirectCallOpt || !isa<Function>(CI.getOperand(0)))
415 Callee = getValueDest(*CI.getOperand(0)).getNode();
417 std::vector<DSNodeHandle> Args;
418 Args.reserve(CI.getNumOperands()-1);
420 // Calculate the arguments vector...
421 for (unsigned i = 1, e = CI.getNumOperands(); i != e; ++i)
422 if (isPointerType(CI.getOperand(i)->getType()))
423 Args.push_back(getValueDest(*CI.getOperand(i)));
425 // Add a new function call entry...
427 FunctionCalls.push_back(DSCallSite(CI, RetVal, Callee, Args));
429 FunctionCalls.push_back(DSCallSite(CI, RetVal,
430 cast<Function>(CI.getOperand(0)), Args));
433 void GraphBuilder::visitFreeInst(FreeInst &FI) {
434 // Mark that the node is written to...
435 DSNode *N = getValueDest(*FI.getOperand(0)).getNode();
436 N->setModifiedMarker();
437 N->setHeapNodeMarker();
441 void GraphBuilder::visitCastInst(CastInst &CI) {
442 if (isPointerType(CI.getType()))
443 if (isPointerType(CI.getOperand(0)->getType())) {
444 // Cast one pointer to the other, just act like a copy instruction
445 setDestTo(CI, getValueDest(*CI.getOperand(0)));
447 // Cast something (floating point, small integer) to a pointer. We need
448 // to track the fact that the node points to SOMETHING, just something we
449 // don't know about. Make an "Unknown" node.
451 setDestTo(CI, createNode()->setUnknownNodeMarker());
456 // visitInstruction - For all other instruction types, if we have any arguments
457 // that are of pointer type, make them have unknown composition bits, and merge
458 // the nodes together.
459 void GraphBuilder::visitInstruction(Instruction &Inst) {
460 DSNodeHandle CurNode;
461 if (isPointerType(Inst.getType()))
462 CurNode = getValueDest(Inst);
463 for (User::op_iterator I = Inst.op_begin(), E = Inst.op_end(); I != E; ++I)
464 if (isPointerType((*I)->getType()))
465 CurNode.mergeWith(getValueDest(**I));
467 if (CurNode.getNode())
468 CurNode.getNode()->setUnknownNodeMarker();
473 //===----------------------------------------------------------------------===//
474 // LocalDataStructures Implementation
475 //===----------------------------------------------------------------------===//
477 bool LocalDataStructures::run(Module &M) {
478 GlobalsGraph = new DSGraph();
480 // Calculate all of the graphs...
481 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
482 if (!I->isExternal())
483 DSInfo.insert(std::make_pair(I, new DSGraph(*I, GlobalsGraph)));
487 // releaseMemory - If the pass pipeline is done with this pass, we can release
488 // our memory... here...
490 void LocalDataStructures::releaseMemory() {
491 for (hash_map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
492 E = DSInfo.end(); I != E; ++I) {
493 I->second->getReturnNodes().erase(I->first);
494 if (I->second->getReturnNodes().empty())
498 // Empty map so next time memory is released, data structures are not