New implementation of data structure analysis. Only local analysis has been

implemented so far.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2871 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 283 insertions, 0 deletions

diff --git a/lib/Analysis/DataStructure/Local.cpp b/lib/Analysis/DataStructure/Local.cpp
new file mode 100644
index 0000000000..87767ce417
--- /dev/null
+++ b/lib/Analysis/DataStructure/Local.cpp
@@ -0,0 +1,283 @@
+//===- ComputeLocal.cpp - Compute a local data structure graph for a fn ---===//
+//
+// 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/Function.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/Support/InstVisitor.h"
+using std::map;
+using std::vector;
+
+//===----------------------------------------------------------------------===//
+//  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.
+//
+
+namespace {
+  class GraphBuilder : InstVisitor<GraphBuilder> {
+    DSGraph &G;
+    vector<DSNode*> &Nodes;
+    DSNodeHandle &RetNode;               // Node that gets returned...
+    map<Value*, DSNodeHandle> &ValueMap;
+    vector<vector<DSNodeHandle> > &FunctionCalls;
+
+  public:
+    GraphBuilder(DSGraph &g, vector<DSNode*> &nodes, DSNodeHandle &retNode,
+                 map<Value*, DSNodeHandle> &vm,
+                 vector<vector<DSNodeHandle> > &fc)
+      : G(g), Nodes(nodes), RetNode(retNode), ValueMap(vm), FunctionCalls(fc) {
+      visit(G.getFunction());  // Single pass over the function
+      removeDeadNodes();
+    }
+
+  private:
+    // Visitor functions, used to handle each instruction type we encounter...
+    friend class InstVisitor<GraphBuilder>;
+    void visitMallocInst(MallocInst &MI) { handleAlloc(MI, DSNode::NewNode); }
+    void visitAllocaInst(AllocaInst &AI) { handleAlloc(AI, DSNode::AllocaNode);}
+    void handleAlloc(AllocationInst &AI, DSNode::NodeTy NT);
+
+    void visitPHINode(PHINode &PN);
+
+    void visitGetElementPtrInst(GetElementPtrInst &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 visitInstruction(Instruction &I) {
+#ifndef NDEBUG
+      bool bad = isa<PointerType>(I.getType());
+      for (Instruction::op_iterator i = I.op_begin(), E = I.op_end(); i!=E; ++i)
+        bad |= isa<PointerType>(i->get()->getType());
+      if (bad) {
+        std::cerr << "\n\n\nUNKNOWN PTR INSTRUCTION type: " << I << "\n\n\n";
+        assert(0 && "Cannot proceed");
+      }
+#endif
+    }
+
+  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);
+
+    // getValueNode - Return a DSNode that corresponds the the specified LLVM
+    // value.  This either returns the already existing node, or creates a new
+    // one and adds it to the graph, if none exists.
+    //
+    DSNode *getValueNode(Value &V);
+
+    // getLink - This method is used to either 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.
+    //
+    DSNode *getLink(DSNode *Node, unsigned Link);
+
+    // getSubscriptedNode - Perform the basic getelementptr functionality that
+    // must be factored out of gep, load and store while they are all MAI's.
+    //
+    DSNode *getSubscriptedNode(MemAccessInst &MAI, DSNode *Ptr);
+
+    // removeDeadNodes - After the graph has been constructed, this method
+    // removes all unreachable nodes that are created because they got merged
+    // with other nodes in the graph.
+    //
+    void removeDeadNodes();
+  };
+}
+
+//===----------------------------------------------------------------------===//
+// DSGraph constructor - Simply use the GraphBuilder to construct the local
+// graph.
+DSGraph::DSGraph(Function &F) : Func(F), RetNode(0) {
+  // Use the graph builder to construct the local version of the graph
+  GraphBuilder B(*this, Nodes, RetNode, ValueMap, FunctionCalls);
+}
+
+
+//===----------------------------------------------------------------------===//
+// Helper method implementations...
+//
+
+
+// createNode - Create a new DSNode, ensuring that it is properly added to the
+// graph.
+//
+DSNode *GraphBuilder::createNode(DSNode::NodeTy NodeType, const Type *Ty) {
+  DSNode *N = new DSNode(NodeType, Ty);
+  Nodes.push_back(N);
+  return N;
+}
+
+
+// getValueNode - Return a DSNode that corresponds the the specified LLVM value.
+// This either returns the already existing node, or creates a new one and adds
+// it to the graph, if none exists.
+//
+DSNode *GraphBuilder::getValueNode(Value &V) {
+  assert(isa<PointerType>(V.getType()) && "Should only use pointer scalars!");
+  DSNodeHandle &N = ValueMap[&V];
+  if (N) return N;             // Already have a node?  Just return it...
+  
+  // Otherwise we need to create a new scalar node...
+  N = createNode(DSNode::ScalarNode, V.getType());
+
+  if (isa<GlobalValue>(V)) {
+    // Traverse the global graph, adding nodes for them all, and marking them
+    // all globals.  Be careful to mark functions global as well as the
+    // potential graph of global variables.
+    //
+    DSNode *G = getLink(N, 0);
+    G->NodeType |= DSNode::GlobalNode;
+  }
+
+  return N;
+}
+
+// getLink - This method is used to either 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.
+//
+DSNode *GraphBuilder::getLink(DSNode *Node, unsigned Link) {
+  assert(Link < Node->getNumLinks() && "Link accessed out of range!");
+  if (Node->getLink(Link) == 0) {
+    DSNode::NodeTy NT;
+    const Type *Ty;
+
+    switch (Node->getType()->getPrimitiveID()) {
+    case Type::PointerTyID:
+      Ty = cast<PointerType>(Node->getType())->getElementType();
+      NT = DSNode::ShadowNode;
+      break;
+    case Type::ArrayTyID:
+      Ty = cast<ArrayType>(Node->getType())->getElementType();
+      NT = DSNode::SubElement;
+      break;
+    case Type::StructTyID:
+      Ty = cast<StructType>(Node->getType())->getContainedType(Link);
+      NT = DSNode::SubElement;
+      break;
+    default:
+      assert(0 && "Unexpected type to dereference!");
+      abort();
+    }
+
+    DSNode *New = createNode(NT, Ty);
+    Node->addEdgeTo(Link, New);
+  }
+
+  return Node->getLink(Link);
+}
+
+// getSubscriptedNode - Perform the basic getelementptr functionality that must
+// be factored out of gep, load and store while they are all MAI's.
+//
+DSNode *GraphBuilder::getSubscriptedNode(MemAccessInst &MAI, DSNode *Ptr) {
+  for (unsigned i = MAI.getFirstIndexOperandNumber(), e = MAI.getNumOperands();
+       i != e; ++i)
+    if (MAI.getOperand(i)->getType() == Type::UIntTy)
+      Ptr = getLink(Ptr, 0);
+    else if (MAI.getOperand(i)->getType() == Type::UByteTy)
+      Ptr = getLink(Ptr, cast<ConstantUInt>(MAI.getOperand(i))->getValue());  
+
+  if (MAI.getFirstIndexOperandNumber() == MAI.getNumOperands())
+    Ptr = getLink(Ptr, 0);  // All MAI's have an implicit 0 if nothing else.
+
+  return Ptr;
+}
+
+
+// removeDeadNodes - After the graph has been constructed, this method removes
+// all unreachable nodes that are created because they got merged with other
+// nodes in the graph.  These nodes will all be trivially unreachable, so we
+// don't have to perform any non-trivial analysis here.
+//
+void GraphBuilder::removeDeadNodes() {
+  for (unsigned i = 0; i != Nodes.size(); )
+    if (!Nodes[i]->getReferrers().empty())
+      ++i;                                    // This node is alive!
+    else {                                    // This node is dead!
+      delete Nodes[i];                        // Free memory...
+      Nodes.erase(Nodes.begin()+i);           // Remove from node list...
+    }
+}
+
+
+
+
+//===----------------------------------------------------------------------===//
+// 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) {
+  DSNode *Scalar = getValueNode(AI);
+  DSNode *New = createNode(NodeType, AI.getAllocatedType());
+  Scalar->addEdgeTo(New);   // Make the scalar point to the new node...
+}
+
+// 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 (!isa<PointerType>(PN.getType())) return; // Only pointer PHIs
+
+  DSNode *Scalar = getValueNode(PN);
+  for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
+    Scalar->mergeWith(getValueNode(*PN.getIncomingValue(i)));
+}
+
+void GraphBuilder::visitGetElementPtrInst(GetElementPtrInst &GEP) {
+  DSNode *Scalar = getValueNode(GEP);
+  DSNode *Ptr    = getSubscriptedNode(GEP, getValueNode(*GEP.getOperand(0)));
+  Scalar->addEdgeTo(Ptr);
+}
+
+void GraphBuilder::visitLoadInst(LoadInst &LI) {
+  if (!isa<PointerType>(LI.getType())) return; // Only pointer PHIs
+  DSNode *Ptr    = getSubscriptedNode(LI, getValueNode(*LI.getOperand(0)));
+  getValueNode(LI)->mergeWith(Ptr);
+}
+
+void GraphBuilder::visitStoreInst(StoreInst &SI) {
+  if (!isa<PointerType>(SI.getOperand(0)->getType())) return;
+  DSNode *Value   = getValueNode(*SI.getOperand(0));
+  DSNode *DestPtr = getValueNode(*SI.getOperand(1));
+  Value->mergeWith(getSubscriptedNode(SI, DestPtr));
+}
+
+void GraphBuilder::visitReturnInst(ReturnInst &RI) {
+  if (RI.getNumOperands() && isa<PointerType>(RI.getOperand(0)->getType())) {
+    DSNode *Value = getValueNode(*RI.getOperand(0));
+    Value->mergeWith(RetNode);
+    RetNode = Value;
+  }
+}
+
+void GraphBuilder::visitCallInst(CallInst &CI) {
+  FunctionCalls.push_back(vector<DSNodeHandle>());
+  vector<DSNodeHandle> &Args = FunctionCalls.back();
+
+  for (unsigned i = 0, e = CI.getNumOperands(); i != e; ++i)
+    if (isa<PointerType>(CI.getOperand(i)->getType()))
+      Args.push_back(getValueNode(*CI.getOperand(i)));
+}