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411 lines
14 KiB
C++
411 lines
14 KiB
C++
//===- Local.cpp - Compute a local data structure graph for a function ----===//
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//
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// Compute the local version of the data structure graph for a function. The
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// external interface to this file is the DSGraph constructor.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/DSGraph.h"
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#include "llvm/Analysis/DataStructure.h"
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#include "llvm/iMemory.h"
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#include "llvm/iTerminators.h"
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#include "llvm/iPHINode.h"
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#include "llvm/iOther.h"
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#include "llvm/Constants.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Function.h"
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#include "llvm/GlobalVariable.h"
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#include "llvm/Support/InstVisitor.h"
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#include "llvm/Target/TargetData.h"
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#include "Support/Statistic.h"
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// FIXME: This should eventually be a FunctionPass that is automatically
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// aggregated into a Pass.
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//
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#include "llvm/Module.h"
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using std::map;
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using std::vector;
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static RegisterAnalysis<LocalDataStructures>
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X("datastructure", "Local Data Structure Analysis");
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namespace DS {
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// FIXME: Do something smarter with target data!
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TargetData TD("temp-td");
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// isPointerType - Return true if this type is big enough to hold a pointer.
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bool isPointerType(const Type *Ty) {
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if (isa<PointerType>(Ty))
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return true;
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else if (Ty->isPrimitiveType() && Ty->isInteger())
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return Ty->getPrimitiveSize() >= PointerSize;
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return false;
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}
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}
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using namespace DS;
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namespace {
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//===--------------------------------------------------------------------===//
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// GraphBuilder Class
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//===--------------------------------------------------------------------===//
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//
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/// This class is the builder class that constructs the local data structure
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/// graph by performing a single pass over the function in question.
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///
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class GraphBuilder : InstVisitor<GraphBuilder> {
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DSGraph &G;
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vector<DSNode*> &Nodes;
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DSNodeHandle &RetNode; // Node that gets returned...
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map<Value*, DSNodeHandle> &ScalarMap;
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vector<DSCallSite> &FunctionCalls;
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public:
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GraphBuilder(DSGraph &g, vector<DSNode*> &nodes, DSNodeHandle &retNode,
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map<Value*, DSNodeHandle> &SM,
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vector<DSCallSite> &fc)
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: G(g), Nodes(nodes), RetNode(retNode), ScalarMap(SM), FunctionCalls(fc) {
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// Create scalar nodes for all pointer arguments...
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for (Function::aiterator I = G.getFunction().abegin(),
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E = G.getFunction().aend(); I != E; ++I)
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if (isPointerType(I->getType()))
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getValueDest(*I);
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visit(G.getFunction()); // Single pass over the function
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// Not inlining, only eliminate trivially dead nodes.
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G.removeTriviallyDeadNodes();
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}
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private:
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// Visitor functions, used to handle each instruction type we encounter...
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friend class InstVisitor<GraphBuilder>;
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void visitMallocInst(MallocInst &MI) { handleAlloc(MI, DSNode::HeapNode); }
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void visitAllocaInst(AllocaInst &AI) { handleAlloc(AI, DSNode::AllocaNode);}
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void handleAlloc(AllocationInst &AI, DSNode::NodeTy NT);
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void visitPHINode(PHINode &PN);
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void visitGetElementPtrInst(GetElementPtrInst &GEP);
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void visitReturnInst(ReturnInst &RI);
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void visitLoadInst(LoadInst &LI);
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void visitStoreInst(StoreInst &SI);
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void visitCallInst(CallInst &CI);
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void visitSetCondInst(SetCondInst &SCI) {} // SetEQ & friends are ignored
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void visitFreeInst(FreeInst &FI) {} // Ignore free instructions
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void visitCastInst(CastInst &CI);
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void visitInstruction(Instruction &I) {}
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private:
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// Helper functions used to implement the visitation functions...
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/// createNode - Create a new DSNode, ensuring that it is properly added to
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/// the graph.
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///
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DSNode *createNode(DSNode::NodeTy NodeType, const Type *Ty = 0) {
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DSNode *N = new DSNode(NodeType, Ty); // Create the node
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Nodes.push_back(N); // Add node to nodes list
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return N;
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}
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/// setDestTo - Set the ScalarMap entry for the specified value to point to
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/// the specified destination. If the Value already points to a node, make
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/// sure to merge the two destinations together.
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///
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void setDestTo(Value &V, const DSNodeHandle &NH);
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/// getValueDest - Return the DSNode that the actual value points to.
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///
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DSNodeHandle getValueDest(Value &V);
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/// getLink - This method is used to return the specified link in the
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/// specified node if one exists. If a link does not already exist (it's
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/// null), then we create a new node, link it, then return it.
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///
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DSNodeHandle &getLink(const DSNodeHandle &Node, unsigned Link = 0);
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};
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}
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//===----------------------------------------------------------------------===//
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// DSGraph constructor - Simply use the GraphBuilder to construct the local
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// graph.
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DSGraph::DSGraph(Function &F) : Func(&F) {
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// Use the graph builder to construct the local version of the graph
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GraphBuilder B(*this, Nodes, RetNode, ScalarMap, FunctionCalls);
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markIncompleteNodes();
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}
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//===----------------------------------------------------------------------===//
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// Helper method implementations...
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//
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/// getValueDest - Return the DSNode that the actual value points to.
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///
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DSNodeHandle GraphBuilder::getValueDest(Value &V) {
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if (Constant *C = dyn_cast<Constant>(&V)) {
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// FIXME: Return null NH for constants like 10 or null
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// FIXME: Handle constant exprs here.
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return 0; // Constant doesn't point to anything.
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}
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DSNodeHandle &NH = ScalarMap[&V];
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if (NH.getNode())
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return NH; // Already have a node? Just return it...
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// Otherwise we need to create a new node to point to...
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DSNode *N;
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if (GlobalValue *GV = dyn_cast<GlobalValue>(&V)) {
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// Create a new global node for this global variable...
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N = createNode(DSNode::GlobalNode, GV->getType()->getElementType());
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N->addGlobal(GV);
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} else {
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// Otherwise just create a shadow node
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N = createNode(DSNode::ShadowNode);
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}
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NH.setNode(N); // Remember that we are pointing to it...
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NH.setOffset(0);
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return NH;
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}
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/// getLink - This method is used to return the specified link in the
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/// specified node if one exists. If a link does not already exist (it's
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/// null), then we create a new node, link it, then return it. We must
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/// specify the type of the Node field we are accessing so that we know what
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/// type should be linked to if we need to create a new node.
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///
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DSNodeHandle &GraphBuilder::getLink(const DSNodeHandle &node, unsigned LinkNo) {
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DSNodeHandle &Node = const_cast<DSNodeHandle&>(node);
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DSNodeHandle &Link = Node.getLink(LinkNo);
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if (!Link.getNode()) {
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// If the link hasn't been created yet, make and return a new shadow node
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Link = createNode(DSNode::ShadowNode);
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}
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return Link;
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}
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/// setDestTo - Set the ScalarMap entry for the specified value to point to the
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/// specified destination. If the Value already points to a node, make sure to
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/// merge the two destinations together.
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///
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void GraphBuilder::setDestTo(Value &V, const DSNodeHandle &NH) {
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DSNodeHandle &AINH = ScalarMap[&V];
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if (AINH.getNode() == 0) // Not pointing to anything yet?
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AINH = NH; // Just point directly to NH
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else
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AINH.mergeWith(NH);
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}
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//===----------------------------------------------------------------------===//
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// Specific instruction type handler implementations...
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//
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/// Alloca & Malloc instruction implementation - Simply create a new memory
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/// object, pointing the scalar to it.
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///
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void GraphBuilder::handleAlloc(AllocationInst &AI, DSNode::NodeTy NodeType) {
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setDestTo(AI, createNode(NodeType));
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}
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// PHINode - Make the scalar for the PHI node point to all of the things the
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// incoming values point to... which effectively causes them to be merged.
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//
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void GraphBuilder::visitPHINode(PHINode &PN) {
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if (!isPointerType(PN.getType())) return; // Only pointer PHIs
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DSNodeHandle &PNDest = ScalarMap[&PN];
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for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
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PNDest.mergeWith(getValueDest(*PN.getIncomingValue(i)));
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}
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void GraphBuilder::visitGetElementPtrInst(GetElementPtrInst &GEP) {
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DSNodeHandle Value = getValueDest(*GEP.getOperand(0));
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if (Value.getNode() == 0) return;
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unsigned Offset = 0;
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const PointerType *PTy = cast<PointerType>(GEP.getOperand(0)->getType());
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const Type *CurTy = PTy->getElementType();
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if (Value.getNode()->mergeTypeInfo(CurTy, Value.getOffset())) {
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// If the node had to be folded... exit quickly
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setDestTo(GEP, Value); // GEP result points to folded node
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return;
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}
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#if 0
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// Handle the pointer index specially...
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if (GEP.getNumOperands() > 1 &&
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GEP.getOperand(1) != ConstantSInt::getNullValue(Type::LongTy)) {
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// If we already know this is an array being accessed, don't do anything...
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if (!TopTypeRec.isArray) {
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TopTypeRec.isArray = true;
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// If we are treating some inner field pointer as an array, fold the node
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// up because we cannot handle it right. This can come because of
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// something like this: &((&Pt->X)[1]) == &Pt->Y
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//
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if (Value.getOffset()) {
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// Value is now the pointer we want to GEP to be...
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Value.getNode()->foldNodeCompletely();
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setDestTo(GEP, Value); // GEP result points to folded node
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return;
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} else {
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// This is a pointer to the first byte of the node. Make sure that we
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// are pointing to the outter most type in the node.
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// FIXME: We need to check one more case here...
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}
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}
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}
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#endif
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// All of these subscripts are indexing INTO the elements we have...
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for (unsigned i = 2, e = GEP.getNumOperands(); i < e; ++i)
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if (GEP.getOperand(i)->getType() == Type::LongTy) {
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// Get the type indexing into...
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const SequentialType *STy = cast<SequentialType>(CurTy);
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CurTy = STy->getElementType();
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#if 0
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if (ConstantSInt *CS = dyn_cast<ConstantSInt>(GEP.getOperand(i))) {
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Offset += CS->getValue()*TD.getTypeSize(CurTy);
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} else {
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// Variable index into a node. We must merge all of the elements of the
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// sequential type here.
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if (isa<PointerType>(STy))
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std::cerr << "Pointer indexing not handled yet!\n";
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else {
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const ArrayType *ATy = cast<ArrayType>(STy);
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unsigned ElSize = TD.getTypeSize(CurTy);
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DSNode *N = Value.getNode();
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assert(N && "Value must have a node!");
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unsigned RawOffset = Offset+Value.getOffset();
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// Loop over all of the elements of the array, merging them into the
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// zero'th element.
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for (unsigned i = 1, e = ATy->getNumElements(); i != e; ++i)
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// Merge all of the byte components of this array element
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for (unsigned j = 0; j != ElSize; ++j)
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N->mergeIndexes(RawOffset+j, RawOffset+i*ElSize+j);
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}
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}
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#endif
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} else if (GEP.getOperand(i)->getType() == Type::UByteTy) {
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unsigned FieldNo = cast<ConstantUInt>(GEP.getOperand(i))->getValue();
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const StructType *STy = cast<StructType>(CurTy);
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Offset += TD.getStructLayout(STy)->MemberOffsets[FieldNo];
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CurTy = STy->getContainedType(FieldNo);
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}
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// Add in the offset calculated...
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Value.setOffset(Value.getOffset()+Offset);
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// Value is now the pointer we want to GEP to be...
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setDestTo(GEP, Value);
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}
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void GraphBuilder::visitLoadInst(LoadInst &LI) {
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DSNodeHandle Ptr = getValueDest(*LI.getOperand(0));
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if (Ptr.getNode() == 0) return;
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// Make that the node is read from...
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Ptr.getNode()->NodeType |= DSNode::Read;
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// Ensure a typerecord exists...
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Ptr.getNode()->mergeTypeInfo(LI.getType(), Ptr.getOffset());
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if (isPointerType(LI.getType()))
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setDestTo(LI, getLink(Ptr));
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}
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void GraphBuilder::visitStoreInst(StoreInst &SI) {
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const Type *StoredTy = SI.getOperand(0)->getType();
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DSNodeHandle Dest = getValueDest(*SI.getOperand(1));
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if (Dest.getNode() == 0) return;
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// Make that the node is written to...
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Dest.getNode()->NodeType |= DSNode::Modified;
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// Ensure a typerecord exists...
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Dest.getNode()->mergeTypeInfo(StoredTy, Dest.getOffset());
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// Avoid adding edges from null, or processing non-"pointer" stores
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if (isPointerType(StoredTy))
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Dest.addEdgeTo(getValueDest(*SI.getOperand(0)));
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}
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void GraphBuilder::visitReturnInst(ReturnInst &RI) {
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if (RI.getNumOperands() && isPointerType(RI.getOperand(0)->getType()))
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RetNode.mergeWith(getValueDest(*RI.getOperand(0)));
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}
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void GraphBuilder::visitCallInst(CallInst &CI) {
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// Set up the return value...
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DSNodeHandle RetVal;
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if (isPointerType(CI.getType()))
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RetVal = getValueDest(CI);
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DSNodeHandle Callee = getValueDest(*CI.getOperand(0));
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std::vector<DSNodeHandle> Args;
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Args.reserve(CI.getNumOperands()-1);
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// Calculate the arguments vector...
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for (unsigned i = 1, e = CI.getNumOperands(); i != e; ++i)
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if (isPointerType(CI.getOperand(i)->getType()))
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Args.push_back(getValueDest(*CI.getOperand(i)));
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// Add a new function call entry...
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FunctionCalls.push_back(DSCallSite(CI, RetVal, Callee, Args));
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}
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/// Handle casts...
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void GraphBuilder::visitCastInst(CastInst &CI) {
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if (isPointerType(CI.getType()))
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if (isPointerType(CI.getOperand(0)->getType())) {
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// Cast one pointer to the other, just act like a copy instruction
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setDestTo(CI, getValueDest(*CI.getOperand(0)));
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} else {
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// Cast something (floating point, small integer) to a pointer. We need
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// to track the fact that the node points to SOMETHING, just something we
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// don't know about. Make an "Unknown" node.
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//
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setDestTo(CI, createNode(DSNode::UnknownNode));
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}
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}
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//===----------------------------------------------------------------------===//
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// LocalDataStructures Implementation
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//===----------------------------------------------------------------------===//
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// releaseMemory - If the pass pipeline is done with this pass, we can release
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// our memory... here...
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//
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void LocalDataStructures::releaseMemory() {
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for (std::map<const Function*, DSGraph*>::iterator I = DSInfo.begin(),
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E = DSInfo.end(); I != E; ++I)
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delete I->second;
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// Empty map so next time memory is released, data structures are not
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// re-deleted.
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DSInfo.clear();
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}
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bool LocalDataStructures::run(Module &M) {
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// Calculate all of the graphs...
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for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
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if (!I->isExternal())
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DSInfo.insert(std::make_pair(I, new DSGraph(*I)));
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return false;
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}
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