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llvm-mirror/lib/Analysis/DataStructure/Local.cpp

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