//===- Local.cpp - Compute a local data structure graph for a function ----===// // // Compute the local version of the data structure graph for a function. The // external interface to this file is the DSGraph constructor. // //===----------------------------------------------------------------------===// #include "llvm/Analysis/DataStructure.h" #include "llvm/Analysis/DSGraph.h" #include "llvm/iMemory.h" #include "llvm/iTerminators.h" #include "llvm/iPHINode.h" #include "llvm/iOther.h" #include "llvm/Constants.h" #include "llvm/DerivedTypes.h" #include "llvm/Function.h" #include "llvm/GlobalVariable.h" #include "llvm/Support/InstVisitor.h" #include "llvm/Target/TargetData.h" #include "Support/Statistic.h" // FIXME: This should eventually be a FunctionPass that is automatically // aggregated into a Pass. // #include "llvm/Module.h" using std::map; using std::vector; static RegisterAnalysis X("datastructure", "Local Data Structure Analysis"); namespace DS { // FIXME: Do something smarter with target data! TargetData TD("temp-td"); // isPointerType - Return true if this type is big enough to hold a pointer. bool isPointerType(const Type *Ty) { if (isa(Ty)) return true; else if (Ty->isPrimitiveType() && Ty->isInteger()) return Ty->getPrimitiveSize() >= PointerSize; return false; } } using namespace DS; namespace { //===--------------------------------------------------------------------===// // GraphBuilder Class //===--------------------------------------------------------------------===// // /// This class is the builder class that constructs the local data structure /// graph by performing a single pass over the function in question. /// class GraphBuilder : InstVisitor { DSGraph &G; vector &Nodes; DSNodeHandle &RetNode; // Node that gets returned... map &ScalarMap; vector &FunctionCalls; public: GraphBuilder(DSGraph &g, vector &nodes, DSNodeHandle &retNode, map &SM, vector &fc) : G(g), Nodes(nodes), RetNode(retNode), ScalarMap(SM), FunctionCalls(fc) { // Create scalar nodes for all pointer arguments... for (Function::aiterator I = G.getFunction().abegin(), E = G.getFunction().aend(); I != E; ++I) if (isPointerType(I->getType())) getValueDest(*I); visit(G.getFunction()); // Single pass over the function // Not inlining, only eliminate trivially dead nodes. G.removeTriviallyDeadNodes(); } private: // Visitor functions, used to handle each instruction type we encounter... friend class InstVisitor; void visitMallocInst(MallocInst &MI) { handleAlloc(MI, DSNode::HeapNode); } void visitAllocaInst(AllocaInst &AI) { handleAlloc(AI, DSNode::AllocaNode);} void handleAlloc(AllocationInst &AI, DSNode::NodeTy NT); void visitPHINode(PHINode &PN); void visitGetElementPtrInst(User &GEP); void visitReturnInst(ReturnInst &RI); void visitLoadInst(LoadInst &LI); void visitStoreInst(StoreInst &SI); void visitCallInst(CallInst &CI); void visitSetCondInst(SetCondInst &SCI) {} // SetEQ & friends are ignored void visitFreeInst(FreeInst &FI) {} // Ignore free instructions void visitCastInst(CastInst &CI); void visitInstruction(Instruction &I) {} private: // Helper functions used to implement the visitation functions... /// createNode - Create a new DSNode, ensuring that it is properly added to /// the graph. /// DSNode *createNode(DSNode::NodeTy NodeType, const Type *Ty = 0) { DSNode *N = new DSNode(NodeType, Ty); // Create the node Nodes.push_back(N); // Add node to nodes list return N; } /// setDestTo - Set the ScalarMap entry for the specified value to point to /// the specified destination. If the Value already points to a node, make /// sure to merge the two destinations together. /// void setDestTo(Value &V, const DSNodeHandle &NH); /// getValueDest - Return the DSNode that the actual value points to. /// DSNodeHandle getValueDest(Value &V); /// getLink - This method is used to return the specified link in the /// specified node if one exists. If a link does not already exist (it's /// null), then we create a new node, link it, then return it. /// DSNodeHandle &getLink(const DSNodeHandle &Node, unsigned Link = 0); }; } //===----------------------------------------------------------------------===// // DSGraph constructor - Simply use the GraphBuilder to construct the local // graph. DSGraph::DSGraph(Function &F) : Func(&F) { // Use the graph builder to construct the local version of the graph GraphBuilder B(*this, Nodes, RetNode, ScalarMap, FunctionCalls); markIncompleteNodes(); } //===----------------------------------------------------------------------===// // Helper method implementations... // /// getValueDest - Return the DSNode that the actual value points to. /// DSNodeHandle GraphBuilder::getValueDest(Value &Val) { Value *V = &Val; if (V == Constant::getNullValue(V->getType())) return 0; // Null doesn't point to anything, don't add to ScalarMap! DSNodeHandle &NH = ScalarMap[V]; if (NH.getNode()) return NH; // Already have a node? Just return it... if (Constant *C = dyn_cast(V)) if (ConstantPointerRef *CPR = dyn_cast(C)) { return NH = getValueDest(*CPR->getValue()); } else if (ConstantExpr *CE = dyn_cast(C)) { if (CE->getOpcode() == Instruction::Cast) return NH = getValueDest(*CE->getOperand(0)); if (CE->getOpcode() == Instruction::GetElementPtr) { visitGetElementPtrInst(*CE); return ScalarMap[CE]; } // This returns a conservative unknown node for any unhandled ConstExpr return NH = createNode(DSNode::UnknownNode); } else if (ConstantIntegral *CI = dyn_cast(C)) { // Random constants are unknown mem return NH = createNode(DSNode::UnknownNode); } else { assert(0 && "Unknown constant type!"); } // Otherwise we need to create a new node to point to... DSNode *N; if (GlobalValue *GV = dyn_cast(V)) { // Create a new global node for this global variable... N = createNode(DSNode::GlobalNode, GV->getType()->getElementType()); N->addGlobal(GV); } else { // Otherwise just create a shadow node N = createNode(DSNode::ShadowNode); } NH.setNode(N); // Remember that we are pointing to it... NH.setOffset(0); return NH; } /// getLink - This method is used to return the specified link in the /// specified node if one exists. If a link does not already exist (it's /// null), then we create a new node, link it, then return it. We must /// specify the type of the Node field we are accessing so that we know what /// type should be linked to if we need to create a new node. /// DSNodeHandle &GraphBuilder::getLink(const DSNodeHandle &node, unsigned LinkNo) { DSNodeHandle &Node = const_cast(node); DSNodeHandle &Link = Node.getLink(LinkNo); if (!Link.getNode()) { // If the link hasn't been created yet, make and return a new shadow node Link = createNode(DSNode::ShadowNode); } return Link; } /// setDestTo - Set the ScalarMap entry for the specified value to point to the /// specified destination. If the Value already points to a node, make sure to /// merge the two destinations together. /// void GraphBuilder::setDestTo(Value &V, const DSNodeHandle &NH) { DSNodeHandle &AINH = ScalarMap[&V]; if (AINH.getNode() == 0) // Not pointing to anything yet? AINH = NH; // Just point directly to NH else AINH.mergeWith(NH); } //===----------------------------------------------------------------------===// // Specific instruction type handler implementations... // /// Alloca & Malloc instruction implementation - Simply create a new memory /// object, pointing the scalar to it. /// void GraphBuilder::handleAlloc(AllocationInst &AI, DSNode::NodeTy NodeType) { setDestTo(AI, createNode(NodeType)); } // PHINode - Make the scalar for the PHI node point to all of the things the // incoming values point to... which effectively causes them to be merged. // void GraphBuilder::visitPHINode(PHINode &PN) { if (!isPointerType(PN.getType())) return; // Only pointer PHIs DSNodeHandle &PNDest = ScalarMap[&PN]; for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) PNDest.mergeWith(getValueDest(*PN.getIncomingValue(i))); } void GraphBuilder::visitGetElementPtrInst(User &GEP) { DSNodeHandle Value = getValueDest(*GEP.getOperand(0)); if (Value.getNode() == 0) return; unsigned Offset = 0; const PointerType *PTy = cast(GEP.getOperand(0)->getType()); const Type *CurTy = PTy->getElementType(); if (Value.getNode()->mergeTypeInfo(CurTy, Value.getOffset())) { // If the node had to be folded... exit quickly setDestTo(GEP, Value); // GEP result points to folded node return; } #if 0 // Handle the pointer index specially... if (GEP.getNumOperands() > 1 && GEP.getOperand(1) != ConstantSInt::getNullValue(Type::LongTy)) { // If we already know this is an array being accessed, don't do anything... if (!TopTypeRec.isArray) { TopTypeRec.isArray = true; // If we are treating some inner field pointer as an array, fold the node // up because we cannot handle it right. This can come because of // something like this: &((&Pt->X)[1]) == &Pt->Y // if (Value.getOffset()) { // Value is now the pointer we want to GEP to be... Value.getNode()->foldNodeCompletely(); setDestTo(GEP, Value); // GEP result points to folded node return; } else { // This is a pointer to the first byte of the node. Make sure that we // are pointing to the outter most type in the node. // FIXME: We need to check one more case here... } } } #endif // All of these subscripts are indexing INTO the elements we have... for (unsigned i = 2, e = GEP.getNumOperands(); i < e; ++i) if (GEP.getOperand(i)->getType() == Type::LongTy) { // Get the type indexing into... const SequentialType *STy = cast(CurTy); CurTy = STy->getElementType(); #if 0 if (ConstantSInt *CS = dyn_cast(GEP.getOperand(i))) { Offset += CS->getValue()*TD.getTypeSize(CurTy); } else { // Variable index into a node. We must merge all of the elements of the // sequential type here. if (isa(STy)) std::cerr << "Pointer indexing not handled yet!\n"; else { const ArrayType *ATy = cast(STy); unsigned ElSize = TD.getTypeSize(CurTy); DSNode *N = Value.getNode(); assert(N && "Value must have a node!"); unsigned RawOffset = Offset+Value.getOffset(); // Loop over all of the elements of the array, merging them into the // zero'th element. for (unsigned i = 1, e = ATy->getNumElements(); i != e; ++i) // Merge all of the byte components of this array element for (unsigned j = 0; j != ElSize; ++j) N->mergeIndexes(RawOffset+j, RawOffset+i*ElSize+j); } } #endif } else if (GEP.getOperand(i)->getType() == Type::UByteTy) { unsigned FieldNo = cast(GEP.getOperand(i))->getValue(); const StructType *STy = cast(CurTy); Offset += TD.getStructLayout(STy)->MemberOffsets[FieldNo]; CurTy = STy->getContainedType(FieldNo); } // Add in the offset calculated... Value.setOffset(Value.getOffset()+Offset); // Value is now the pointer we want to GEP to be... setDestTo(GEP, Value); } void GraphBuilder::visitLoadInst(LoadInst &LI) { DSNodeHandle Ptr = getValueDest(*LI.getOperand(0)); if (Ptr.getNode() == 0) return; // Make that the node is read from... Ptr.getNode()->NodeType |= DSNode::Read; // Ensure a typerecord exists... Ptr.getNode()->mergeTypeInfo(LI.getType(), Ptr.getOffset()); if (isPointerType(LI.getType())) setDestTo(LI, getLink(Ptr)); } void GraphBuilder::visitStoreInst(StoreInst &SI) { const Type *StoredTy = SI.getOperand(0)->getType(); DSNodeHandle Dest = getValueDest(*SI.getOperand(1)); if (Dest.getNode() == 0) return; // Make that the node is written to... Dest.getNode()->NodeType |= DSNode::Modified; // Ensure a typerecord exists... Dest.getNode()->mergeTypeInfo(StoredTy, Dest.getOffset()); // Avoid adding edges from null, or processing non-"pointer" stores if (isPointerType(StoredTy)) Dest.addEdgeTo(getValueDest(*SI.getOperand(0))); } void GraphBuilder::visitReturnInst(ReturnInst &RI) { if (RI.getNumOperands() && isPointerType(RI.getOperand(0)->getType())) RetNode.mergeWith(getValueDest(*RI.getOperand(0))); } void GraphBuilder::visitCallInst(CallInst &CI) { // Set up the return value... DSNodeHandle RetVal; if (isPointerType(CI.getType())) RetVal = getValueDest(CI); DSNodeHandle Callee = getValueDest(*CI.getOperand(0)); std::vector Args; Args.reserve(CI.getNumOperands()-1); // Calculate the arguments vector... for (unsigned i = 1, e = CI.getNumOperands(); i != e; ++i) if (isPointerType(CI.getOperand(i)->getType())) Args.push_back(getValueDest(*CI.getOperand(i))); // Add a new function call entry... FunctionCalls.push_back(DSCallSite(CI, RetVal, Callee, Args)); } /// Handle casts... void GraphBuilder::visitCastInst(CastInst &CI) { if (isPointerType(CI.getType())) if (isPointerType(CI.getOperand(0)->getType())) { // Cast one pointer to the other, just act like a copy instruction setDestTo(CI, getValueDest(*CI.getOperand(0))); } else { // Cast something (floating point, small integer) to a pointer. We need // to track the fact that the node points to SOMETHING, just something we // don't know about. Make an "Unknown" node. // setDestTo(CI, createNode(DSNode::UnknownNode)); } } //===----------------------------------------------------------------------===// // LocalDataStructures Implementation //===----------------------------------------------------------------------===// // releaseMemory - If the pass pipeline is done with this pass, we can release // our memory... here... // void LocalDataStructures::releaseMemory() { for (std::map::iterator I = DSInfo.begin(), E = DSInfo.end(); I != E; ++I) delete I->second; // Empty map so next time memory is released, data structures are not // re-deleted. DSInfo.clear(); } bool LocalDataStructures::run(Module &M) { // Calculate all of the graphs... for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) if (!I->isExternal()) DSInfo.insert(std::make_pair(I, new DSGraph(*I))); return false; }