llvm-6502/lib/Analysis/DataStructure/Local.cpp
2003-09-24 23:42:58 +00:00

588 lines
20 KiB
C++

//===- 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/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Instructions.h"
#include "llvm/Support/InstVisitor.h"
#include "llvm/Target/TargetData.h"
#include "Support/CommandLine.h"
#include "Support/Debug.h"
#include "Support/Timer.h"
// FIXME: This should eventually be a FunctionPass that is automatically
// aggregated into a Pass.
//
#include "llvm/Module.h"
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 {
cl::opt<bool>
DisableDirectCallOpt("disable-direct-call-dsopt", cl::Hidden,
cl::desc("Disable direct call optimization in "
"DSGraph construction"));
cl::opt<bool>
DisableFieldSensitivity("disable-ds-field-sensitivity", cl::Hidden,
cl::desc("Disable field sensitivity in DSGraphs"));
//===--------------------------------------------------------------------===//
// 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;
DSNodeHandle *RetNode; // Node that gets returned...
DSGraph::ScalarMapTy &ScalarMap;
std::vector<DSCallSite> *FunctionCalls;
public:
GraphBuilder(Function &f, DSGraph &g, DSNodeHandle &retNode,
std::vector<DSCallSite> &fc)
: G(g), RetNode(&retNode), ScalarMap(G.getScalarMap()),
FunctionCalls(&fc) {
// Create scalar nodes for all pointer arguments...
for (Function::aiterator I = f.abegin(), E = f.aend(); I != E; ++I)
if (isPointerType(I->getType()))
getValueDest(*I);
visit(f); // Single pass over the function
}
// GraphBuilder ctor for working on the globals graph
GraphBuilder(DSGraph &g)
: G(g), RetNode(0), ScalarMap(G.getScalarMap()), FunctionCalls(0) {
}
void mergeInGlobalInitializer(GlobalVariable *GV);
private:
// Visitor functions, used to handle each instruction type we encounter...
friend class InstVisitor<GraphBuilder>;
void visitMallocInst(MallocInst &MI) { handleAlloc(MI, true); }
void visitAllocaInst(AllocaInst &AI) { handleAlloc(AI, false); }
void handleAlloc(AllocationInst &AI, bool isHeap);
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 visitInvokeInst(InvokeInst &II);
void visitSetCondInst(SetCondInst &SCI) {} // SetEQ & friends are ignored
void visitFreeInst(FreeInst &FI);
void visitCastInst(CastInst &CI);
void visitInstruction(Instruction &I);
void visitCallSite(CallSite CS);
void MergeConstantInitIntoNode(DSNodeHandle &NH, Constant *C);
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(const Type *Ty = 0) {
DSNode *N = new DSNode(Ty, &G); // Create the node
if (DisableFieldSensitivity) {
N->foldNodeCompletely();
if (DSNode *FN = N->getForwardNode())
N = FN;
}
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
/// null), then we create a new node, link it, then return it.
///
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) : GlobalsGraph(GG) {
PrintAuxCalls = false;
DEBUG(std::cerr << " [Loc] Calculating graph for: " << F.getName() << "\n");
// Use the graph builder to construct the local version of the graph
GraphBuilder B(F, *this, ReturnNodes[&F], FunctionCalls);
#ifndef NDEBUG
Timer::addPeakMemoryMeasurement();
#endif
// Remove all integral constants from the scalarmap!
for (ScalarMapTy::iterator I = ScalarMap.begin(); I != ScalarMap.end();)
if (isa<ConstantIntegral>(I->first)) {
ScalarMapTy::iterator J = I++;
ScalarMap.erase(J);
} else
++I;
markIncompleteNodes(DSGraph::MarkFormalArgs);
// Remove any nodes made dead due to merging...
removeDeadNodes(DSGraph::KeepUnreachableGlobals);
}
//===----------------------------------------------------------------------===//
// 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!
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.
// Check first for constant expressions that must be traversed to
// extract the actual value.
if (Constant *C = dyn_cast<Constant>(V))
if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(C)) {
return NH = getValueDest(*CPR->getValue());
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
if (CE->getOpcode() == Instruction::Cast)
NH = getValueDest(*CE->getOperand(0));
else if (CE->getOpcode() == Instruction::GetElementPtr) {
visitGetElementPtrInst(*CE);
DSGraph::ScalarMapTy::iterator I = ScalarMap.find(CE);
assert(I != ScalarMap.end() && "GEP didn't get processed right?");
NH = I->second;
} else {
// This returns a conservative unknown node for any unhandled ConstExpr
return NH = createNode()->setUnknownNodeMarker();
}
if (NH.getNode() == 0) { // (getelementptr null, X) returns null
ScalarMap.erase(V);
return 0;
}
return NH;
} else if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(C)) {
// Random constants are unknown mem
return NH = createNode()->setUnknownNodeMarker();
} else {
assert(0 && "Unknown constant type!");
}
// 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(GV->getType()->getElementType());
N->addGlobal(GV);
} else {
// Otherwise just create a shadow node
N = createNode();
}
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.
///
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();
}
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, bool isHeap) {
DSNode *N = createNode();
if (isHeap)
N->setHeapNodeMarker();
else
N->setAllocaNodeMarker();
setDestTo(AI, N);
}
// 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;
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...
unsigned Offset = 0;
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
// zeroth 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...
Ptr.getNode()->setReadMarker();
// Ensure a typerecord exists...
Ptr.getNode()->mergeTypeInfo(LI.getType(), Ptr.getOffset(), false);
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;
// Mark that the node is written to...
Dest.getNode()->setModifiedMarker();
// Ensure a type-record 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) {
visitCallSite(&CI);
}
void GraphBuilder::visitInvokeInst(InvokeInst &II) {
visitCallSite(&II);
}
void GraphBuilder::visitCallSite(CallSite CS) {
// Special case handling of certain libc allocation functions here.
if (Function *F = CS.getCalledFunction())
if (F->isExternal())
if (F->getName() == "calloc") {
setDestTo(*CS.getInstruction(),
createNode()->setHeapNodeMarker()->setModifiedMarker());
return;
} else if (F->getName() == "realloc") {
DSNodeHandle RetNH = getValueDest(*CS.getInstruction());
RetNH.mergeWith(getValueDest(**CS.arg_begin()));
DSNode *N = RetNH.getNode();
if (N) N->setHeapNodeMarker()->setModifiedMarker()->setReadMarker();
return;
}
// Set up the return value...
DSNodeHandle RetVal;
Instruction *I = CS.getInstruction();
if (isPointerType(I->getType()))
RetVal = getValueDest(*I);
DSNode *Callee = 0;
if (DisableDirectCallOpt || !isa<Function>(CS.getCalledValue())) {
Callee = getValueDest(*CS.getCalledValue()).getNode();
if (Callee == 0) {
std::cerr << "WARNING: Program is calling through a null pointer?\n"
<< *I;
return; // Calling a null pointer?
}
}
std::vector<DSNodeHandle> Args;
Args.reserve(CS.arg_end()-CS.arg_begin());
// Calculate the arguments vector...
for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); I != E; ++I)
if (isPointerType((*I)->getType()))
Args.push_back(getValueDest(**I));
// Add a new function call entry...
if (Callee)
FunctionCalls->push_back(DSCallSite(CS, RetVal, Callee, Args));
else
FunctionCalls->push_back(DSCallSite(CS, RetVal, CS.getCalledFunction(),
Args));
}
void GraphBuilder::visitFreeInst(FreeInst &FI) {
// Mark that the node is written to...
DSNode *N = getValueDest(*FI.getOperand(0)).getNode();
N->setModifiedMarker();
N->setHeapNodeMarker();
}
/// 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()->setUnknownNodeMarker());
}
}
// visitInstruction - For all other instruction types, if we have any arguments
// that are of pointer type, make them have unknown composition bits, and merge
// the nodes together.
void GraphBuilder::visitInstruction(Instruction &Inst) {
DSNodeHandle CurNode;
if (isPointerType(Inst.getType()))
CurNode = getValueDest(Inst);
for (User::op_iterator I = Inst.op_begin(), E = Inst.op_end(); I != E; ++I)
if (isPointerType((*I)->getType()))
CurNode.mergeWith(getValueDest(**I));
if (CurNode.getNode())
CurNode.getNode()->setUnknownNodeMarker();
}
//===----------------------------------------------------------------------===//
// LocalDataStructures Implementation
//===----------------------------------------------------------------------===//
// MergeConstantInitIntoNode - Merge the specified constant into the node
// pointed to by NH.
void GraphBuilder::MergeConstantInitIntoNode(DSNodeHandle &NH, Constant *C) {
// Ensure a type-record exists...
NH.getNode()->mergeTypeInfo(C->getType(), NH.getOffset());
if (C->getType()->isFirstClassType()) {
if (isPointerType(C->getType()))
// Avoid adding edges from null, or processing non-"pointer" stores
NH.addEdgeTo(getValueDest(*C));
return;
}
if (ConstantArray *CA = dyn_cast<ConstantArray>(C)) {
for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
// We don't currently do any indexing for arrays...
MergeConstantInitIntoNode(NH, cast<Constant>(CA->getOperand(i)));
} else if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
const StructLayout *SL = TD.getStructLayout(CS->getType());
for (unsigned i = 0, e = CS->getNumOperands(); i != e; ++i) {
DSNodeHandle NewNH(NH.getNode(), NH.getOffset()+SL->MemberOffsets[i]);
MergeConstantInitIntoNode(NewNH, cast<Constant>(CS->getOperand(i)));
}
} else {
assert(0 && "Unknown constant type!");
}
}
void GraphBuilder::mergeInGlobalInitializer(GlobalVariable *GV) {
assert(!GV->isExternal() && "Cannot merge in external global!");
// Get a node handle to the global node and merge the initializer into it.
DSNodeHandle NH = getValueDest(*GV);
MergeConstantInitIntoNode(NH, GV->getInitializer());
}
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)));
GraphBuilder GGB(*GlobalsGraph);
// Add initializers for all of the globals to the globals graph...
for (Module::giterator I = M.gbegin(), E = M.gend(); I != E; ++I)
if (!I->isExternal())
GGB.mergeInGlobalInitializer(I);
GlobalsGraph->markIncompleteNodes(DSGraph::MarkFormalArgs);
GlobalsGraph->removeTriviallyDeadNodes();
return false;
}
// releaseMemory - If the pass pipeline is done with this pass, we can release
// our memory... here...
//
void LocalDataStructures::releaseMemory() {
for (hash_map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
E = DSInfo.end(); I != E; ++I) {
I->second->getReturnNodes().erase(I->first);
if (I->second->getReturnNodes().empty())
delete I->second;
}
// Empty map so next time memory is released, data structures are not
// re-deleted.
DSInfo.clear();
delete GlobalsGraph;
GlobalsGraph = 0;
}