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());
219 /// getLink - This method is used to return the specified link in the
220 /// specified node if one exists. If a link does not already exist (it's
221 /// null), then we create a new node, link it, then return it. We must
222 /// specify the type of the Node field we are accessing so that we know what
223 /// type should be linked to if we need to create a new node.
225 DSNodeHandle &GraphBuilder::getLink(const DSNodeHandle &node,
226 unsigned LinkNo, const Type *FieldTy) {
227 DSNodeHandle &Node = const_cast<DSNodeHandle&>(node);
229 DSNodeHandle *Link = Node.getLink(LinkNo);
230 if (Link) return *Link;
232 // If the link hasn't been created yet, make and return a new shadow node of
233 // the appropriate type for FieldTy...
236 // If we are indexing with a typed pointer, then the thing we are pointing
237 // to is of the pointed type. If we are pointing to it with an integer
238 // (because of cast to an integer), we represent it with a void type.
241 if (const PointerType *Ptr = dyn_cast<PointerType>(FieldTy))
242 ReqTy = Ptr->getElementType();
244 ReqTy = Type::VoidTy;
246 DSNode *N = createNode(DSNode::ShadowNode, ReqTy);
247 Node.setLink(LinkNo, N);
248 return *Node.getLink(LinkNo);
252 //===----------------------------------------------------------------------===//
253 // Specific instruction type handler implementations...
256 /// Alloca & Malloc instruction implementation - Simply create a new memory
257 /// object, pointing the scalar to it.
259 void GraphBuilder::handleAlloc(AllocationInst &AI, DSNode::NodeTy NodeType) {
260 DSNode *New = createNode(NodeType, AI.getAllocatedType());
262 // Make the scalar point to the new node...
263 getValueNode(AI).addEdgeTo(New);
266 // PHINode - Make the scalar for the PHI node point to all of the things the
267 // incoming values point to... which effectively causes them to be merged.
269 void GraphBuilder::visitPHINode(PHINode &PN) {
270 if (!isPointerType(PN.getType())) return; // Only pointer PHIs
272 DSNodeHandle &ScalarDest = getValueDest(PN);
273 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
274 if (!isa<ConstantPointerNull>(PN.getIncomingValue(i)))
275 ScalarDest.mergeWith(getValueDest(*PN.getIncomingValue(i)));
278 void GraphBuilder::visitGetElementPtrInst(GetElementPtrInst &GEP) {
279 DSNodeHandle Value = getValueDest(*GEP.getOperand(0));
282 const Type *CurTy = GEP.getOperand(0)->getType();
284 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i)
285 if (GEP.getOperand(i)->getType() == Type::LongTy) {
286 // Get the type indexing into...
287 const SequentialType *STy = cast<SequentialType>(CurTy);
288 CurTy = STy->getElementType();
289 if (ConstantSInt *CS = dyn_cast<ConstantSInt>(GEP.getOperand(i))) {
290 if (isa<PointerType>(STy))
291 std::cerr << "Pointer indexing not handled yet!\n";
293 Offset += CS->getValue()*TD.getTypeSize(CurTy);
295 // Variable index into a node. We must merge all of the elements of the
296 // sequential type here.
297 if (isa<PointerType>(STy))
298 std::cerr << "Pointer indexing not handled yet!\n";
300 const ArrayType *ATy = cast<ArrayType>(STy);
301 unsigned ElSize = TD.getTypeSize(CurTy);
302 DSNode *N = Value.getNode();
303 assert(N && "Value must have a node!");
304 unsigned RawOffset = Offset+Value.getOffset();
306 // Loop over all of the elements of the array, merging them into the
308 for (unsigned i = 1, e = ATy->getNumElements(); i != e; ++i)
309 // Merge all of the byte components of this array element
310 for (unsigned j = 0; j != ElSize; ++j)
311 N->mergeIndexes(RawOffset+j, RawOffset+i*ElSize+j);
314 } else if (GEP.getOperand(i)->getType() == Type::UByteTy) {
315 unsigned FieldNo = cast<ConstantUInt>(GEP.getOperand(i))->getValue();
316 const StructType *STy = cast<StructType>(CurTy);
317 Offset += TD.getStructLayout(STy)->MemberOffsets[FieldNo];
318 CurTy = STy->getContainedType(FieldNo);
321 // Add in the offset calculated...
322 Value.setOffset(Value.getOffset()+Offset);
324 // Value is now the pointer we want to GEP to be...
325 getValueNode(GEP).addEdgeTo(Value);
328 void GraphBuilder::visitLoadInst(LoadInst &LI) {
329 DSNodeHandle &Ptr = getValueDest(*LI.getOperand(0));
330 Ptr.getNode()->NodeType |= DSNode::Read;
332 if (isPointerType(LI.getType()))
333 getValueNode(LI).addEdgeTo(getLink(Ptr, 0, LI.getType()));
336 void GraphBuilder::visitStoreInst(StoreInst &SI) {
337 DSNodeHandle &Dest = getValueDest(*SI.getOperand(1));
338 Dest.getNode()->NodeType |= DSNode::Modified;
340 // Avoid adding edges from null, or processing non-"pointer" stores
341 if (isPointerType(SI.getOperand(0)->getType()) &&
342 !isa<ConstantPointerNull>(SI.getOperand(0))) {
343 Dest.addEdgeTo(getValueDest(*SI.getOperand(0)));
347 void GraphBuilder::visitReturnInst(ReturnInst &RI) {
348 if (RI.getNumOperands() && isPointerType(RI.getOperand(0)->getType()) &&
349 !isa<ConstantPointerNull>(RI.getOperand(0))) {
350 DSNodeHandle &Value = getValueDest(*RI.getOperand(0));
351 Value.mergeWith(RetNode);
356 void GraphBuilder::visitCallInst(CallInst &CI) {
357 // Add a new function call entry...
358 FunctionCalls.push_back(CI);
359 DSCallSite &Args = FunctionCalls.back();
361 // Set up the return value...
362 if (isPointerType(CI.getType()))
363 Args.push_back(getLink(getValueNode(CI), 0, CI.getType()));
365 Args.push_back(DSNodeHandle());
368 // Special case for a direct call, avoid creating spurious scalar node...
369 if (GlobalValue *GV = dyn_cast<GlobalValue>(CI.getOperand(0))) {
370 Args.push_back(getGlobalNode(*GV));
374 // Pass the arguments in...
375 for (unsigned i = Start, e = CI.getNumOperands(); i != e; ++i)
376 if (isPointerType(CI.getOperand(i)->getType()))
377 Args.push_back(getLink(getValueNode(*CI.getOperand(i)), 0,
378 CI.getOperand(i)->getType()));
382 void GraphBuilder::visitCastInst(CastInst &CI) {
383 if (isPointerType(CI.getType()) && isPointerType(CI.getOperand(0)->getType()))
384 getValueNode(CI).addEdgeTo(getLink(getValueNode(*CI.getOperand(0)), 0,
385 CI.getOperand(0)->getType()));
391 //===----------------------------------------------------------------------===//
392 // LocalDataStructures Implementation
393 //===----------------------------------------------------------------------===//
395 // releaseMemory - If the pass pipeline is done with this pass, we can release
396 // our memory... here...
398 void LocalDataStructures::releaseMemory() {
399 for (std::map<const Function*, DSGraph*>::iterator I = DSInfo.begin(),
400 E = DSInfo.end(); I != E; ++I)
403 // Empty map so next time memory is released, data structures are not
408 bool LocalDataStructures::run(Module &M) {
409 // Calculate all of the graphs...
410 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
411 if (!I->isExternal())
412 DSInfo.insert(std::make_pair(I, new DSGraph(*I)));