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 = 0) {
110 DSNode *N = new DSNode(NodeType, Ty); // Create the node
111 Nodes.push_back(N); // Add node to nodes list
115 /// setDestTo - Set the ValueMap entry for the specified value to point to
116 /// the specified destination. If the Value already points to a node, make
117 /// sure to merge the two destinations together.
119 void setDestTo(Value &V, const DSNodeHandle &NH);
121 /// getValueDest - Return the DSNode that the actual value points to.
123 DSNodeHandle getValueDest(Value &V);
125 /// getLink - This method is used to return the specified link in the
126 /// specified node if one exists. If a link does not already exist (it's
127 /// null), then we create a new node, link it, then return it.
129 DSNodeHandle &getLink(const DSNodeHandle &Node, unsigned Link = 0);
133 //===----------------------------------------------------------------------===//
134 // DSGraph constructor - Simply use the GraphBuilder to construct the local
136 DSGraph::DSGraph(Function &F) : Func(&F) {
137 // Use the graph builder to construct the local version of the graph
138 GraphBuilder B(*this, Nodes, RetNode, ValueMap, FunctionCalls);
139 markIncompleteNodes();
143 //===----------------------------------------------------------------------===//
144 // Helper method implementations...
148 /// getValueDest - Return the DSNode that the actual value points to.
150 DSNodeHandle GraphBuilder::getValueDest(Value &V) {
151 if (Constant *C = dyn_cast<Constant>(&V)) {
152 // FIXME: Return null NH for constants like 10 or null
153 // FIXME: Handle constant exprs here.
155 return 0; // Constant doesn't point to anything.
158 DSNodeHandle &NH = ValueMap[&V];
160 return NH; // Already have a node? Just return it...
162 // Otherwise we need to create a new node to point to...
164 if (GlobalValue *GV = dyn_cast<GlobalValue>(&V)) {
165 // Create a new global node for this global variable...
166 N = createNode(DSNode::GlobalNode, GV->getType()->getElementType());
169 // Otherwise just create a shadow node
170 N = createNode(DSNode::ShadowNode);
173 NH.setNode(N); // Remember that we are pointing to it...
179 /// getLink - This method is used to return the specified link in the
180 /// specified node if one exists. If a link does not already exist (it's
181 /// null), then we create a new node, link it, then return it. We must
182 /// specify the type of the Node field we are accessing so that we know what
183 /// type should be linked to if we need to create a new node.
185 DSNodeHandle &GraphBuilder::getLink(const DSNodeHandle &node, unsigned LinkNo) {
186 DSNodeHandle &Node = const_cast<DSNodeHandle&>(node);
187 DSNodeHandle *Link = Node.getLink(LinkNo);
188 if (Link) return *Link;
190 // If the link hasn't been created yet, make and return a new shadow node
191 DSNode *N = createNode(DSNode::ShadowNode);
192 Node.setLink(LinkNo, N);
193 return *Node.getLink(LinkNo);
197 /// setDestTo - Set the ValueMap entry for the specified value to point to the
198 /// specified destination. If the Value already points to a node, make sure to
199 /// merge the two destinations together.
201 void GraphBuilder::setDestTo(Value &V, const DSNodeHandle &NH) {
202 DSNodeHandle &AINH = ValueMap[&V];
203 if (AINH.getNode() == 0) // Not pointing to anything yet?
204 AINH = NH; // Just point directly to NH
210 //===----------------------------------------------------------------------===//
211 // Specific instruction type handler implementations...
214 /// Alloca & Malloc instruction implementation - Simply create a new memory
215 /// object, pointing the scalar to it.
217 void GraphBuilder::handleAlloc(AllocationInst &AI, DSNode::NodeTy NodeType) {
218 setDestTo(AI, createNode(NodeType));
221 // PHINode - Make the scalar for the PHI node point to all of the things the
222 // incoming values point to... which effectively causes them to be merged.
224 void GraphBuilder::visitPHINode(PHINode &PN) {
225 if (!isPointerType(PN.getType())) return; // Only pointer PHIs
227 DSNodeHandle &PNDest = ValueMap[&PN];
228 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
229 PNDest.mergeWith(getValueDest(*PN.getIncomingValue(i)));
232 void GraphBuilder::visitGetElementPtrInst(GetElementPtrInst &GEP) {
233 DSNodeHandle Value = getValueDest(*GEP.getOperand(0));
234 if (Value.getNode() == 0) return;
237 const PointerType *PTy = cast<PointerType>(GEP.getOperand(0)->getType());
238 const Type *CurTy = PTy->getElementType();
239 DSTypeRec &TopTypeRec =
240 Value.getNode()->getTypeRec(PTy->getElementType(), Value.getOffset());
242 // If the node had to be folded... exit quickly
243 if (TopTypeRec.Ty == Type::VoidTy) {
244 setDestTo(GEP, Value); // GEP result points to folded node
248 // Handle the pointer index specially...
249 if (GEP.getNumOperands() > 1 &&
250 GEP.getOperand(1) != ConstantSInt::getNullValue(Type::LongTy)) {
252 // If we already know this is an array being accessed, don't do anything...
253 if (!TopTypeRec.isArray) {
254 TopTypeRec.isArray = true;
256 // If we are treating some inner field pointer as an array, fold the node
257 // up because we cannot handle it right. This can come because of
258 // something like this: &((&Pt->X)[1]) == &Pt->Y
260 if (Value.getOffset()) {
261 // Value is now the pointer we want to GEP to be...
262 Value.getNode()->foldNodeCompletely();
263 setDestTo(GEP, Value); // GEP result points to folded node
266 // This is a pointer to the first byte of the node. Make sure that we
267 // are pointing to the outter most type in the node.
268 // FIXME: We need to check one more case here...
273 // All of these subscripts are indexing INTO the elements we have...
274 for (unsigned i = 2, e = GEP.getNumOperands(); i < e; ++i)
275 if (GEP.getOperand(i)->getType() == Type::LongTy) {
276 // Get the type indexing into...
277 const SequentialType *STy = cast<SequentialType>(CurTy);
278 CurTy = STy->getElementType();
279 if (ConstantSInt *CS = dyn_cast<ConstantSInt>(GEP.getOperand(i))) {
280 Offset += CS->getValue()*TD.getTypeSize(CurTy);
282 // Variable index into a node. We must merge all of the elements of the
283 // sequential type here.
284 if (isa<PointerType>(STy))
285 std::cerr << "Pointer indexing not handled yet!\n";
287 const ArrayType *ATy = cast<ArrayType>(STy);
288 unsigned ElSize = TD.getTypeSize(CurTy);
289 DSNode *N = Value.getNode();
290 assert(N && "Value must have a node!");
291 unsigned RawOffset = Offset+Value.getOffset();
293 // Loop over all of the elements of the array, merging them into the
295 for (unsigned i = 1, e = ATy->getNumElements(); i != e; ++i)
296 // Merge all of the byte components of this array element
297 for (unsigned j = 0; j != ElSize; ++j)
298 N->mergeIndexes(RawOffset+j, RawOffset+i*ElSize+j);
301 } else if (GEP.getOperand(i)->getType() == Type::UByteTy) {
302 unsigned FieldNo = cast<ConstantUInt>(GEP.getOperand(i))->getValue();
303 const StructType *STy = cast<StructType>(CurTy);
304 Offset += TD.getStructLayout(STy)->MemberOffsets[FieldNo];
305 CurTy = STy->getContainedType(FieldNo);
308 // Add in the offset calculated...
309 Value.setOffset(Value.getOffset()+Offset);
311 // Value is now the pointer we want to GEP to be...
312 setDestTo(GEP, Value);
315 void GraphBuilder::visitLoadInst(LoadInst &LI) {
316 DSNodeHandle Ptr = getValueDest(*LI.getOperand(0));
317 if (Ptr.getNode() == 0) return;
319 // Make that the node is read from...
320 Ptr.getNode()->NodeType |= DSNode::Read;
322 // Ensure a typerecord exists...
323 Ptr.getNode()->getTypeRec(LI.getType(), Ptr.getOffset());
325 if (isPointerType(LI.getType()))
326 setDestTo(LI, getLink(Ptr));
329 void GraphBuilder::visitStoreInst(StoreInst &SI) {
330 const Type *StoredTy = SI.getOperand(0)->getType();
331 DSNodeHandle Dest = getValueDest(*SI.getOperand(1));
332 if (Dest.getNode() == 0) return;
334 // Make that the node is written to...
335 Dest.getNode()->NodeType |= DSNode::Modified;
337 // Ensure a typerecord exists...
338 Dest.getNode()->getTypeRec(StoredTy, Dest.getOffset());
340 // Avoid adding edges from null, or processing non-"pointer" stores
341 if (isPointerType(StoredTy))
342 Dest.addEdgeTo(getValueDest(*SI.getOperand(0)));
345 void GraphBuilder::visitReturnInst(ReturnInst &RI) {
346 if (RI.getNumOperands() && isPointerType(RI.getOperand(0)->getType()))
347 RetNode.mergeWith(getValueDest(*RI.getOperand(0)));
350 void GraphBuilder::visitCallInst(CallInst &CI) {
351 // Set up the return value...
353 if (isPointerType(CI.getType()))
354 RetVal = getValueDest(CI);
356 DSNodeHandle Callee = getValueDest(*CI.getOperand(0));
358 std::vector<DSNodeHandle> Args;
359 Args.reserve(CI.getNumOperands()-1);
361 // Calculate the arguments vector...
362 for (unsigned i = 1, e = CI.getNumOperands(); i != e; ++i)
363 if (isPointerType(CI.getOperand(i)->getType()))
364 Args.push_back(getValueDest(*CI.getOperand(i)));
366 // Add a new function call entry...
367 FunctionCalls.push_back(DSCallSite(CI, RetVal, Callee, Args));
371 void GraphBuilder::visitCastInst(CastInst &CI) {
372 if (isPointerType(CI.getType())) {
373 if (isPointerType(CI.getOperand(0)->getType()))
374 setDestTo(CI, getValueDest(*CI.getOperand(0)));
376 ; // FIXME: "Other" node
383 //===----------------------------------------------------------------------===//
384 // LocalDataStructures Implementation
385 //===----------------------------------------------------------------------===//
387 // releaseMemory - If the pass pipeline is done with this pass, we can release
388 // our memory... here...
390 void LocalDataStructures::releaseMemory() {
391 for (std::map<const Function*, DSGraph*>::iterator I = DSInfo.begin(),
392 E = DSInfo.end(); I != E; ++I)
395 // Empty map so next time memory is released, data structures are not
400 bool LocalDataStructures::run(Module &M) {
401 // Calculate all of the graphs...
402 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
403 if (!I->isExternal())
404 DSInfo.insert(std::make_pair(I, new DSGraph(*I)));