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/DSGraph.h"
9 #include "llvm/Analysis/DataStructure.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"
22 // FIXME: This should eventually be a FunctionPass that is automatically
23 // aggregated into a Pass.
25 #include "llvm/Module.h"
30 static RegisterAnalysis<LocalDataStructures>
31 X("datastructure", "Local Data Structure Analysis");
33 using namespace DataStructureAnalysis;
35 namespace DataStructureAnalysis {
36 // FIXME: Do something smarter with target data!
37 TargetData TD("temp-td");
38 unsigned PointerSize(TD.getPointerSize());
40 // isPointerType - Return true if this type is big enough to hold a pointer.
41 bool isPointerType(const Type *Ty) {
42 if (isa<PointerType>(Ty))
44 else if (Ty->isPrimitiveType() && Ty->isInteger())
45 return Ty->getPrimitiveSize() >= PointerSize;
52 //===--------------------------------------------------------------------===//
54 //===--------------------------------------------------------------------===//
56 /// This class is the builder class that constructs the local data structure
57 /// graph by performing a single pass over the function in question.
59 class GraphBuilder : InstVisitor<GraphBuilder> {
61 vector<DSNode*> &Nodes;
62 DSNodeHandle &RetNode; // Node that gets returned...
63 map<Value*, DSNodeHandle> &ValueMap;
64 vector<DSCallSite> &FunctionCalls;
67 GraphBuilder(DSGraph &g, vector<DSNode*> &nodes, DSNodeHandle &retNode,
68 map<Value*, DSNodeHandle> &vm,
69 vector<DSCallSite> &fc)
70 : G(g), Nodes(nodes), RetNode(retNode), ValueMap(vm), FunctionCalls(fc) {
72 // Create scalar nodes for all pointer arguments...
73 for (Function::aiterator I = G.getFunction().abegin(),
74 E = G.getFunction().aend(); I != E; ++I)
75 if (isPointerType(I->getType()))
78 visit(G.getFunction()); // Single pass over the function
80 // Not inlining, only eliminate trivially dead nodes.
81 G.removeTriviallyDeadNodes();
85 // Visitor functions, used to handle each instruction type we encounter...
86 friend class InstVisitor<GraphBuilder>;
87 void visitMallocInst(MallocInst &MI) { handleAlloc(MI, DSNode::NewNode); }
88 void visitAllocaInst(AllocaInst &AI) { handleAlloc(AI, DSNode::AllocaNode);}
89 void handleAlloc(AllocationInst &AI, DSNode::NodeTy NT);
91 void visitPHINode(PHINode &PN);
93 void visitGetElementPtrInst(GetElementPtrInst &GEP);
94 void visitReturnInst(ReturnInst &RI);
95 void visitLoadInst(LoadInst &LI);
96 void visitStoreInst(StoreInst &SI);
97 void visitCallInst(CallInst &CI);
98 void visitSetCondInst(SetCondInst &SCI) {} // SetEQ & friends are ignored
99 void visitFreeInst(FreeInst &FI) {} // Ignore free instructions
100 void visitCastInst(CastInst &CI);
101 void visitInstruction(Instruction &I) {}
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(DSNode::NodeTy NodeType, const Type *Ty);
111 /// getValueNode - Return a DSNode that corresponds the the specified LLVM
112 /// value. This either returns the already existing node, or creates a new
113 /// one and adds it to the graph, if none exists.
115 DSNodeHandle getValueNode(Value &V);
117 /// getValueDest - Return the DSNode that the actual value points to. This
118 /// is basically the same thing as: getLink(getValueNode(V), 0)
120 DSNodeHandle &getValueDest(Value &V);
122 /// getGlobalNode - Just like getValueNode, except the global node itself is
123 /// returned, not a scalar node pointing to a global.
125 DSNodeHandle &getGlobalNode(GlobalValue &V);
127 /// getLink - This method is used to return the specified link in the
128 /// specified node if one exists. If a link does not already exist (it's
129 /// null), then we create a new node, link it, then return it. We must
130 /// specify the type of the Node field we are accessing so that we know what
131 /// type should be linked to if we need to create a new node.
133 DSNodeHandle &getLink(const DSNodeHandle &Node, unsigned Link,
134 const Type *FieldTy);
138 //===----------------------------------------------------------------------===//
139 // DSGraph constructor - Simply use the GraphBuilder to construct the local
141 DSGraph::DSGraph(Function &F) : Func(&F) {
142 // Use the graph builder to construct the local version of the graph
143 GraphBuilder B(*this, Nodes, RetNode, ValueMap, FunctionCalls);
144 markIncompleteNodes();
148 //===----------------------------------------------------------------------===//
149 // Helper method implementations...
153 // createNode - Create a new DSNode, ensuring that it is properly added to the
156 DSNode *GraphBuilder::createNode(DSNode::NodeTy NodeType, const Type *Ty) {
157 DSNode *N = new DSNode(NodeType, Ty);
163 // getGlobalNode - Just like getValueNode, except the global node itself is
164 // returned, not a scalar node pointing to a global.
166 DSNodeHandle &GraphBuilder::getGlobalNode(GlobalValue &V) {
167 DSNodeHandle &NH = ValueMap[&V];
168 if (NH.getNode()) return NH; // Already have a node? Just return it...
170 // Create a new global node for this global variable...
171 DSNode *G = createNode(DSNode::GlobalNode, V.getType()->getElementType());
174 // If this node has outgoing edges, make sure to recycle the same node for
175 // each use. For functions and other global variables, this is unneccesary,
176 // so avoid excessive merging by cloning these nodes on demand.
183 // getValueNode - Return a DSNode that corresponds the the specified LLVM value.
184 // This either returns the already existing node, or creates a new one and adds
185 // it to the graph, if none exists.
187 DSNodeHandle GraphBuilder::getValueNode(Value &V) {
188 assert(isPointerType(V.getType()) && "Should only use pointer scalars!");
189 // Do not share the pointer value to globals... this would cause way too much
192 DSNodeHandle &NH = ValueMap[&V];
193 if (!isa<GlobalValue>(V) && NH.getNode())
194 return NH; // Already have a node? Just return it...
196 // Otherwise we need to create a new scalar node...
197 DSNode *N = createNode(DSNode::ScalarNode, V.getType());
199 // If this is a global value, create the global pointed to.
200 if (GlobalValue *GV = dyn_cast<GlobalValue>(&V)) {
201 N->addEdgeTo(0, getGlobalNode(*GV));
202 return DSNodeHandle(N, 0);
211 /// getValueDest - Return the DSNode that the actual value points to. This
212 /// is basically the same thing as: getLink(getValueNode(V), 0)
214 DSNodeHandle &GraphBuilder::getValueDest(Value &V) {
215 return getLink(getValueNode(V), 0, V.getType());
220 /// getLink - This method is used to return the specified link in the
221 /// specified node if one exists. If a link does not already exist (it's
222 /// null), then we create a new node, link it, then return it. We must
223 /// specify the type of the Node field we are accessing so that we know what
224 /// type should be linked to if we need to create a new node.
226 DSNodeHandle &GraphBuilder::getLink(const DSNodeHandle &node,
227 unsigned LinkNo, const Type *FieldTy) {
228 DSNodeHandle &Node = const_cast<DSNodeHandle&>(node);
230 DSNodeHandle *Link = Node.getLink(LinkNo);
231 if (Link) return *Link;
233 // If the link hasn't been created yet, make and return a new shadow node of
234 // the appropriate type for FieldTy...
237 // If we are indexing with a typed pointer, then the thing we are pointing
238 // to is of the pointed type. If we are pointing to it with an integer
239 // (because of cast to an integer), we represent it with a void type.
242 if (const PointerType *Ptr = dyn_cast<PointerType>(FieldTy))
243 ReqTy = Ptr->getElementType();
245 ReqTy = Type::VoidTy;
247 DSNode *N = createNode(DSNode::ShadowNode, ReqTy);
248 Node.setLink(LinkNo, N);
249 return *Node.getLink(LinkNo);
253 //===----------------------------------------------------------------------===//
254 // Specific instruction type handler implementations...
257 /// Alloca & Malloc instruction implementation - Simply create a new memory
258 /// object, pointing the scalar to it.
260 void GraphBuilder::handleAlloc(AllocationInst &AI, DSNode::NodeTy NodeType) {
261 DSNode *New = createNode(NodeType, AI.getAllocatedType());
263 // Make the scalar point to the new node...
264 getValueNode(AI).addEdgeTo(New);
267 // PHINode - Make the scalar for the PHI node point to all of the things the
268 // incoming values point to... which effectively causes them to be merged.
270 void GraphBuilder::visitPHINode(PHINode &PN) {
271 if (!isPointerType(PN.getType())) return; // Only pointer PHIs
273 DSNodeHandle &ScalarDest = getValueDest(PN);
274 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
275 if (!isa<ConstantPointerNull>(PN.getIncomingValue(i)))
276 ScalarDest.mergeWith(getValueDest(*PN.getIncomingValue(i)));
279 void GraphBuilder::visitGetElementPtrInst(GetElementPtrInst &GEP) {
280 DSNodeHandle Value = getValueDest(*GEP.getOperand(0));
283 const Type *CurTy = GEP.getOperand(0)->getType();
285 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i)
286 if (GEP.getOperand(i)->getType() == Type::LongTy) {
287 // Get the type indexing into...
288 const SequentialType *STy = cast<SequentialType>(CurTy);
289 CurTy = STy->getElementType();
290 if (ConstantSInt *CS = dyn_cast<ConstantSInt>(GEP.getOperand(i))) {
291 if (isa<PointerType>(STy))
292 std::cerr << "Pointer indexing not handled yet!\n";
294 Offset += CS->getValue()*TD.getTypeSize(CurTy);
296 // Variable index into a node. We must merge all of the elements of the
297 // sequential type here.
298 if (isa<PointerType>(STy))
299 std::cerr << "Pointer indexing not handled yet!\n";
301 const ArrayType *ATy = cast<ArrayType>(STy);
302 unsigned ElSize = TD.getTypeSize(CurTy);
303 DSNode *N = Value.getNode();
304 assert(N && "Value must have a node!");
305 unsigned RawOffset = Offset+Value.getOffset();
307 // Loop over all of the elements of the array, merging them into the
309 for (unsigned i = 1, e = ATy->getNumElements(); i != e; ++i)
310 // Merge all of the byte components of this array element
311 for (unsigned j = 0; j != ElSize; ++j)
312 N->mergeIndexes(RawOffset+j, RawOffset+i*ElSize+j);
315 } else if (GEP.getOperand(i)->getType() == Type::UByteTy) {
316 unsigned FieldNo = cast<ConstantUInt>(GEP.getOperand(i))->getValue();
317 const StructType *STy = cast<StructType>(CurTy);
318 Offset += TD.getStructLayout(STy)->MemberOffsets[FieldNo];
319 CurTy = STy->getContainedType(FieldNo);
322 // Add in the offset calculated...
323 Value.setOffset(Value.getOffset()+Offset);
325 // Value is now the pointer we want to GEP to be...
326 getValueNode(GEP).addEdgeTo(Value);
329 void GraphBuilder::visitLoadInst(LoadInst &LI) {
330 DSNodeHandle &Ptr = getValueDest(*LI.getOperand(0));
331 Ptr.getNode()->NodeType |= DSNode::Read;
333 if (isPointerType(LI.getType()))
334 getValueNode(LI).addEdgeTo(getLink(Ptr, 0, LI.getType()));
337 void GraphBuilder::visitStoreInst(StoreInst &SI) {
338 DSNodeHandle &Dest = getValueDest(*SI.getOperand(1));
339 Dest.getNode()->NodeType |= DSNode::Modified;
341 // Avoid adding edges from null, or processing non-"pointer" stores
342 if (isPointerType(SI.getOperand(0)->getType()) &&
343 !isa<ConstantPointerNull>(SI.getOperand(0))) {
344 Dest.addEdgeTo(getValueDest(*SI.getOperand(0)));
348 void GraphBuilder::visitReturnInst(ReturnInst &RI) {
349 if (RI.getNumOperands() && isPointerType(RI.getOperand(0)->getType()) &&
350 !isa<ConstantPointerNull>(RI.getOperand(0))) {
351 DSNodeHandle &Value = getValueDest(*RI.getOperand(0));
352 Value.mergeWith(RetNode);
357 void GraphBuilder::visitCallInst(CallInst &CI) {
358 // Add a new function call entry...
359 FunctionCalls.push_back(DSCallSite(CI));
360 DSCallSite &Args = FunctionCalls.back();
362 // Set up the return value...
363 if (isPointerType(CI.getType()))
364 Args.push_back(getLink(getValueNode(CI), 0, CI.getType()));
366 Args.push_back(DSNodeHandle());
369 // Special case for a direct call, avoid creating spurious scalar node...
370 if (GlobalValue *GV = dyn_cast<GlobalValue>(CI.getOperand(0))) {
371 Args.push_back(getGlobalNode(*GV));
375 // Pass the arguments in...
376 for (unsigned i = Start, e = CI.getNumOperands(); i != e; ++i)
377 if (isPointerType(CI.getOperand(i)->getType()))
378 Args.push_back(getLink(getValueNode(*CI.getOperand(i)), 0,
379 CI.getOperand(i)->getType()));
383 void GraphBuilder::visitCastInst(CastInst &CI) {
384 if (isPointerType(CI.getType()) && isPointerType(CI.getOperand(0)->getType()))
385 getValueNode(CI).addEdgeTo(getLink(getValueNode(*CI.getOperand(0)), 0,
386 CI.getOperand(0)->getType()));
392 //===----------------------------------------------------------------------===//
393 // LocalDataStructures Implementation
394 //===----------------------------------------------------------------------===//
396 // releaseMemory - If the pass pipeline is done with this pass, we can release
397 // our memory... here...
399 void LocalDataStructures::releaseMemory() {
400 for (std::map<const Function*, DSGraph*>::iterator I = DSInfo.begin(),
401 E = DSInfo.end(); I != E; ++I)
404 // Empty map so next time memory is released, data structures are not
409 bool LocalDataStructures::run(Module &M) {
410 // Calculate all of the graphs...
411 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
412 if (!I->isExternal())
413 DSInfo.insert(std::make_pair(I, new DSGraph(*I)));