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llvm-mirror/lib/Analysis/DataStructure/Local.cpp
2002-07-30 22:08:08 +00:00

325 lines
12 KiB
C++

//===- 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/GlobalVariable.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Support/InstVisitor.h"
using std::map;
using std::vector;
static RegisterAnalysis<LocalDataStructures>
X("datastructure", "Local Data Structure Analysis");
AnalysisID LocalDataStructures::ID = X;
//===----------------------------------------------------------------------===//
// 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) {
// Create scalar nodes for all pointer arguments...
for (Function::aiterator I = G.getFunction().abegin(),
E = G.getFunction().aend(); I != E; ++I)
if (isa<PointerType>(I->getType()))
getValueNode(*I);
visit(G.getFunction()); // Single pass over the function
// Not inlining, only eliminate trivially dead nodes.
G.removeTriviallyDeadNodes();
}
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); // Visit unsafe ptr instruction
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);
// getGlobalNode - Just like getValueNode, except the global node itself is
// returned, not a scalar node pointing to a global.
//
DSNode *getGlobalNode(GlobalValue &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);
};
}
//===----------------------------------------------------------------------===//
// DSGraph constructor - Simply use the GraphBuilder to construct the local
// graph.
DSGraph::DSGraph(Function &F, GlobalDSGraph* GlobalsG)
: Func(F), RetNode(0), GlobalsGraph(GlobalsG) {
if (GlobalsGraph != this) {
GlobalsGraph->addReference(this);
// Use the graph builder to construct the local version of the graph
GraphBuilder B(*this, Nodes, RetNode, ValueMap, FunctionCalls);
markIncompleteNodes();
}
}
//===----------------------------------------------------------------------===//
// 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;
}
// getGlobalNode - Just like getValueNode, except the global node itself is
// returned, not a scalar node pointing to a global.
//
DSNode *GraphBuilder::getGlobalNode(GlobalValue &V) {
DSNodeHandle &NH = ValueMap[&V];
if (NH) return NH; // Already have a node? Just return it...
// Create a new global node for this global variable...
DSNode *G = createNode(DSNode::GlobalNode, V.getType()->getElementType());
G->addGlobal(&V);
// If this node has outgoing edges, make sure to recycle the same node for
// each use. For functions and other global variables, this is unneccesary,
// so avoid excessive merging by cloning these nodes on demand.
//
NH = G;
return G;
}
// 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!");
if (!isa<GlobalValue>(V)) {
DSNodeHandle &NH = ValueMap[&V];
if (NH) return NH; // Already have a node? Just return it...
}
// Otherwise we need to create a new scalar node...
DSNode *N = createNode(DSNode::ScalarNode, V.getType());
// If this is a global value, create the global pointed to.
if (GlobalValue *GV = dyn_cast<GlobalValue>(&V)) {
DSNode *G = getGlobalNode(*GV);
N->addEdgeTo(G);
} else {
ValueMap[&V] = N;
}
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;
}
//===----------------------------------------------------------------------===//
// 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);
DSNode *ScalarDest = getLink(Scalar, 0);
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
ScalarDest->mergeWith(getLink(getValueNode(*PN.getIncomingValue(i)), 0));
}
void GraphBuilder::visitGetElementPtrInst(GetElementPtrInst &GEP) {
DSNode *Ptr = getSubscriptedNode(GEP, getValueNode(*GEP.getOperand(0)));
getValueNode(GEP)->addEdgeTo(Ptr);
}
void GraphBuilder::visitLoadInst(LoadInst &LI) {
DSNode *Ptr = getSubscriptedNode(LI, getValueNode(*LI.getOperand(0)));
if (!isa<PointerType>(LI.getType())) return; // Only pointer PHIs
getValueNode(LI)->addEdgeTo(getLink(Ptr, 0));
}
void GraphBuilder::visitStoreInst(StoreInst &SI) {
DSNode *DestPtr = getSubscriptedNode(SI, getValueNode(*SI.getOperand(1)));
if (!isa<PointerType>(SI.getOperand(0)->getType())) return;
DSNode *Value = getValueNode(*SI.getOperand(0));
DestPtr->addEdgeTo(getLink(Value, 0));
}
void GraphBuilder::visitReturnInst(ReturnInst &RI) {
if (RI.getNumOperands() && isa<PointerType>(RI.getOperand(0)->getType())) {
DSNode *Value = getLink(getValueNode(*RI.getOperand(0)), 0);
Value->mergeWith(RetNode);
RetNode = Value;
}
}
void GraphBuilder::visitCallInst(CallInst &CI) {
// Add a new function call entry...
FunctionCalls.push_back(vector<DSNodeHandle>());
vector<DSNodeHandle> &Args = FunctionCalls.back();
// Set up the return value...
if (isa<PointerType>(CI.getType()))
Args.push_back(getLink(getValueNode(CI), 0));
else
Args.push_back(0);
unsigned Start = 0;
// Special case for direct call, avoid creating spurious scalar node...
if (GlobalValue *GV = dyn_cast<GlobalValue>(CI.getOperand(0))) {
Args.push_back(getGlobalNode(*GV));
Start = 1;
}
// Pass the arguments in...
for (unsigned i = Start, e = CI.getNumOperands(); i != e; ++i)
if (isa<PointerType>(CI.getOperand(i)->getType()))
Args.push_back(getLink(getValueNode(*CI.getOperand(i)), 0));
}
// visitInstruction - All safe instructions have been processed above, this case
// is where unsafe ptr instructions land.
//
void GraphBuilder::visitInstruction(Instruction &I) {
// If the return type is a pointer, mark the pointed node as being a cast node
if (isa<PointerType>(I.getType()))
getLink(getValueNode(I), 0)->NodeType |= DSNode::CastNode;
// If any operands are pointers, mark the pointed nodes as being a cast node
for (Instruction::op_iterator i = I.op_begin(), E = I.op_end(); i!=E; ++i)
if (isa<PointerType>(i->get()->getType()))
getLink(getValueNode(*i->get()), 0)->NodeType |= DSNode::CastNode;
}