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llvm-6502/lib/Analysis/DataStructure/Local.cpp
Andrew Lenharth 26c2e73da6 no heap is happening here 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26781 91177308-0d34-0410-b5e6-96231b3b80d8
2006-03-15 19:03:16 +00:00

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//===- Local.cpp - Compute a local data structure graph for a function ----===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// 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/DataStructure.h"
#include "llvm/Analysis/DataStructure/DSGraph.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/InstVisitor.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Timer.h"
#include <iostream>
// FIXME: This should eventually be a FunctionPass that is automatically
// aggregated into a Pass.
//
#include "llvm/Module.h"
using namespace llvm;
static RegisterAnalysis<LocalDataStructures>
X("datastructure", "Local Data Structure Analysis");
static cl::opt<bool>
TrackIntegersAsPointers("dsa-track-integers", cl::Hidden,
cl::desc("If this is set, track integers as potential pointers"));
static cl::list<std::string>
AllocList("dsa-alloc-list",
cl::value_desc("list"),
cl::desc("List of functions that allocate memory from the heap"),
cl::CommaSeparated, cl::Hidden);
static cl::list<std::string>
FreeList("dsa-free-list",
cl::value_desc("list"),
cl::desc("List of functions that free memory from the heap"),
cl::CommaSeparated, cl::Hidden);
namespace llvm {
namespace DS {
// 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 (TrackIntegersAsPointers && 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...
DSScalarMap &ScalarMap;
std::list<DSCallSite> *FunctionCalls;
public:
GraphBuilder(Function &f, DSGraph &g, DSNodeHandle &retNode,
std::list<DSCallSite> &fc)
: G(g), RetNode(&retNode), ScalarMap(G.getScalarMap()),
FunctionCalls(&fc) {
// Create scalar nodes for all pointer arguments...
for (Function::arg_iterator I = f.arg_begin(), E = f.arg_end();
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 visitSelectInst(SelectInst &SI);
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);
void visitFreeInst(FreeInst &FI);
void visitCastInst(CastInst &CI);
void visitInstruction(Instruction &I);
void visitCallSite(CallSite CS);
void visitVAArgInst(VAArgInst &I);
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) {
// Create node handle referring to the old node so that it is
// immediately removed from the graph when the node handle is destroyed.
DSNodeHandle OldNNH = N;
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);
};
}
using namespace DS;
//===----------------------------------------------------------------------===//
// DSGraph constructor - Simply use the GraphBuilder to construct the local
// graph.
DSGraph::DSGraph(EquivalenceClasses<GlobalValue*> &ECs, const TargetData &td,
Function &F, DSGraph *GG)
: GlobalsGraph(GG), ScalarMap(ECs), TD(td) {
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
// If there are any constant globals referenced in this function, merge their
// initializers into the local graph from the globals graph.
if (ScalarMap.global_begin() != ScalarMap.global_end()) {
ReachabilityCloner RC(*this, *GG, 0);
for (DSScalarMap::global_iterator I = ScalarMap.global_begin();
I != ScalarMap.global_end(); ++I)
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(*I))
if (!GV->isExternal() && GV->isConstant())
RC.merge(ScalarMap[GV], GG->ScalarMap[GV]);
}
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 (isa<Constant>(V) && cast<Constant>(V)->isNullValue())
return 0; // Null doesn't point to anything, don't add to ScalarMap!
DSNodeHandle &NH = ScalarMap[V];
if (!NH.isNull())
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.
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 if (Constant *C = dyn_cast<Constant>(V)) {
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
if (CE->getOpcode() == Instruction::Cast) {
if (isa<PointerType>(CE->getOperand(0)->getType()))
NH = getValueDest(*CE->getOperand(0));
else
NH = createNode()->setUnknownNodeMarker();
} else if (CE->getOpcode() == Instruction::GetElementPtr) {
visitGetElementPtrInst(*CE);
DSScalarMap::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.isNull()) { // (getelementptr null, X) returns null
ScalarMap.erase(V);
return 0;
}
return NH;
} else if (isa<UndefValue>(C)) {
ScalarMap.erase(V);
return 0;
} else {
assert(0 && "Unknown constant type!");
}
N = createNode(); // just create a shadow node
} else {
// Otherwise just create a shadow node
N = createNode();
}
NH.setTo(N, 0); // Remember that we are pointing to it...
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.isNull()) {
// 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) {
ScalarMap[&V].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::visitSelectInst(SelectInst &SI) {
if (!isPointerType(SI.getType())) return; // Only pointer Selects
DSNodeHandle &Dest = ScalarMap[&SI];
Dest.mergeWith(getValueDest(*SI.getOperand(1)));
Dest.mergeWith(getValueDest(*SI.getOperand(2)));
}
void GraphBuilder::visitSetCondInst(SetCondInst &SCI) {
if (!isPointerType(SCI.getOperand(0)->getType()) ||
isa<ConstantPointerNull>(SCI.getOperand(1))) return; // Only pointers
ScalarMap[SCI.getOperand(0)].mergeWith(getValueDest(*SCI.getOperand(1)));
}
void GraphBuilder::visitGetElementPtrInst(User &GEP) {
DSNodeHandle Value = getValueDest(*GEP.getOperand(0));
if (Value.isNull())
Value = createNode();
// As a special case, if all of the index operands of GEP are constant zeros,
// handle this just like we handle casts (ie, don't do much).
bool AllZeros = true;
for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i)
if (GEP.getOperand(i) !=
Constant::getNullValue(GEP.getOperand(i)->getType())) {
AllZeros = false;
break;
}
// If all of the indices are zero, the result points to the operand without
// applying the type.
if (AllZeros || (!Value.isNull() &&
Value.getNode()->isNodeCompletelyFolded())) {
setDestTo(GEP, Value);
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;
}
const TargetData &TD = Value.getNode()->getTargetData();
#if 0
// Handle the pointer index specially...
if (GEP.getNumOperands() > 1 &&
(!isa<Constant>(GEP.getOperand(1)) ||
!cast<Constant>(GEP.getOperand(1))->isNullValue())) {
// 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 (gep_type_iterator I = gep_type_begin(GEP), E = gep_type_end(GEP);
I != E; ++I)
if (const StructType *STy = dyn_cast<StructType>(*I)) {
unsigned FieldNo =
(unsigned)cast<ConstantUInt>(I.getOperand())->getValue();
Offset += (unsigned)TD.getStructLayout(STy)->MemberOffsets[FieldNo];
} else if (const PointerType *PTy = dyn_cast<PointerType>(*I)) {
if (!isa<Constant>(I.getOperand()) ||
!cast<Constant>(I.getOperand())->isNullValue())
Value.getNode()->setArrayMarker();
}
#if 0
if (const SequentialType *STy = cast<SequentialType>(*I)) {
CurTy = STy->getElementType();
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
// Add in the offset calculated...
Value.setOffset(Value.getOffset()+Offset);
// Check the offset
DSNode *N = Value.getNode();
if (N &&
!N->isNodeCompletelyFolded() &&
(N->getSize() != 0 || Offset != 0) &&
!N->isForwarding()) {
if ((Offset >= N->getSize()) || int(Offset) < 0) {
// Accessing offsets out of node size range
// This is seen in the "magic" struct in named (from bind), where the
// fourth field is an array of length 0, presumably used to create struct
// instances of different sizes
// Collapse the node since its size is now variable
N->foldNodeCompletely();
}
}
// 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.isNull())
Ptr = createNode();
// 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.isNull()) 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::visitVAArgInst(VAArgInst &I) {
//FIXME: also updates the argument
DSNodeHandle Ptr = getValueDest(*I.getOperand(0));
if (Ptr.isNull()) return;
// Make that the node is read from.
Ptr.getNode()->setReadMarker();
// Ensure a type record exists.
DSNode *PtrN = Ptr.getNode();
PtrN->mergeTypeInfo(I.getType(), Ptr.getOffset(), false);
if (isPointerType(I.getType()))
setDestTo(I, getLink(Ptr));
}
void GraphBuilder::visitCallInst(CallInst &CI) {
visitCallSite(&CI);
}
void GraphBuilder::visitInvokeInst(InvokeInst &II) {
visitCallSite(&II);
}
void GraphBuilder::visitCallSite(CallSite CS) {
Value *Callee = CS.getCalledValue();
// Special case handling of certain libc allocation functions here.
if (Function *F = dyn_cast<Function>(Callee))
if (F->isExternal())
switch (F->getIntrinsicID()) {
case Intrinsic::vastart:
getValueDest(*CS.getInstruction()).getNode()->setAllocaNodeMarker();
return;
case Intrinsic::vacopy:
getValueDest(*CS.getInstruction()).
mergeWith(getValueDest(**(CS.arg_begin())));
return;
case Intrinsic::vaend:
return; // noop
case Intrinsic::memcpy_i32:
case Intrinsic::memcpy_i64: {
//write first location
if (DSNode *N = getValueDest(**CS.arg_begin()).getNode())
N->setModifiedMarker();
//and read second pointer
if (DSNode *N = getValueDest(**(CS.arg_begin() + 1)).getNode())
N->setReadMarker();
return;
}
case Intrinsic::memmove_i32:
case Intrinsic::memmove_i64: {
// Merge the first & second arguments, and mark the memory read and
// modified.
DSNodeHandle RetNH = getValueDest(**CS.arg_begin());
RetNH.mergeWith(getValueDest(**(CS.arg_begin()+1)));
if (DSNode *N = RetNH.getNode())
N->setModifiedMarker()->setReadMarker();
return;
}
case Intrinsic::memset_i32:
case Intrinsic::memset_i64:
// Mark the memory modified.
if (DSNode *N = getValueDest(**CS.arg_begin()).getNode())
N->setModifiedMarker();
return;
default:
// Determine if the called function is one of the specified heap
// allocation functions
for (cl::list<std::string>::iterator AllocFunc = AllocList.begin(),
LastAllocFunc = AllocList.end();
AllocFunc != LastAllocFunc;
++AllocFunc) {
if (F->getName() == *(AllocFunc)) {
setDestTo(*CS.getInstruction(),
createNode()->setHeapNodeMarker()->setModifiedMarker());
return;
}
}
// Determine if the called function is one of the specified heap
// free functions
for (cl::list<std::string>::iterator FreeFunc = FreeList.begin(),
LastFreeFunc = FreeList.end();
FreeFunc != LastFreeFunc;
++FreeFunc) {
if (F->getName() == *(FreeFunc)) {
// Mark that the node is written to...
if (DSNode *N = getValueDest(*(CS.getArgument(0))).getNode())
N->setModifiedMarker()->setHeapNodeMarker();
return;
}
}
if (F->getName() == "calloc" || F->getName() == "posix_memalign" ||
F->getName() == "memalign" || F->getName() == "valloc") {
setDestTo(*CS.getInstruction(),
createNode()->setHeapNodeMarker()->setModifiedMarker());
return;
} else if (F->getName() == "realloc") {
DSNodeHandle RetNH = getValueDest(*CS.getInstruction());
if (CS.arg_begin() != CS.arg_end())
RetNH.mergeWith(getValueDest(**CS.arg_begin()));
if (DSNode *N = RetNH.getNode())
N->setHeapNodeMarker()->setModifiedMarker()->setReadMarker();
return;
} else if (F->getName() == "memmove") {
// Merge the first & second arguments, and mark the memory read and
// modified.
DSNodeHandle RetNH = getValueDest(**CS.arg_begin());
RetNH.mergeWith(getValueDest(**(CS.arg_begin()+1)));
if (DSNode *N = RetNH.getNode())
N->setModifiedMarker()->setReadMarker();
return;
} else if (F->getName() == "atoi" || F->getName() == "atof" ||
F->getName() == "atol" || F->getName() == "atoll" ||
F->getName() == "remove" || F->getName() == "unlink" ||
F->getName() == "rename" || F->getName() == "memcmp" ||
F->getName() == "strcmp" || F->getName() == "strncmp" ||
F->getName() == "execl" || F->getName() == "execlp" ||
F->getName() == "execle" || F->getName() == "execv" ||
F->getName() == "execvp" || F->getName() == "chmod" ||
F->getName() == "puts" || F->getName() == "write" ||
F->getName() == "open" || F->getName() == "create" ||
F->getName() == "truncate" || F->getName() == "chdir" ||
F->getName() == "mkdir" || F->getName() == "rmdir") {
// These functions read all of their pointer operands.
for (CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end();
AI != E; ++AI) {
if (isPointerType((*AI)->getType()))
if (DSNode *N = getValueDest(**AI).getNode())
N->setReadMarker();
}
return;
} else if (F->getName() == "read" || F->getName() == "pipe" ||
F->getName() == "wait" || F->getName() == "time") {
// These functions write all of their pointer operands.
for (CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end();
AI != E; ++AI) {
if (isPointerType((*AI)->getType()))
if (DSNode *N = getValueDest(**AI).getNode())
N->setModifiedMarker();
}
return;
} else if (F->getName() == "stat" || F->getName() == "fstat" ||
F->getName() == "lstat") {
// These functions read their first operand if its a pointer.
CallSite::arg_iterator AI = CS.arg_begin();
if (isPointerType((*AI)->getType())) {
DSNodeHandle Path = getValueDest(**AI);
if (DSNode *N = Path.getNode()) N->setReadMarker();
}
// Then they write into the stat buffer.
DSNodeHandle StatBuf = getValueDest(**++AI);
if (DSNode *N = StatBuf.getNode()) {
N->setModifiedMarker();
const Type *StatTy = F->getFunctionType()->getParamType(1);
if (const PointerType *PTy = dyn_cast<PointerType>(StatTy))
N->mergeTypeInfo(PTy->getElementType(), StatBuf.getOffset());
}
return;
} else if (F->getName() == "strtod" || F->getName() == "strtof" ||
F->getName() == "strtold") {
// These functions read the first pointer
if (DSNode *Str = getValueDest(**CS.arg_begin()).getNode()) {
Str->setReadMarker();
// If the second parameter is passed, it will point to the first
// argument node.
const DSNodeHandle &EndPtrNH = getValueDest(**(CS.arg_begin()+1));
if (DSNode *End = EndPtrNH.getNode()) {
End->mergeTypeInfo(PointerType::get(Type::SByteTy),
EndPtrNH.getOffset(), false);
End->setModifiedMarker();
DSNodeHandle &Link = getLink(EndPtrNH);
Link.mergeWith(getValueDest(**CS.arg_begin()));
}
}
return;
} else if (F->getName() == "fopen" || F->getName() == "fdopen" ||
F->getName() == "freopen") {
// These functions read all of their pointer operands.
for (CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end();
AI != E; ++AI)
if (isPointerType((*AI)->getType()))
if (DSNode *N = getValueDest(**AI).getNode())
N->setReadMarker();
// fopen allocates in an unknown way and writes to the file
// descriptor. Also, merge the allocated type into the node.
DSNodeHandle Result = getValueDest(*CS.getInstruction());
if (DSNode *N = Result.getNode()) {
N->setModifiedMarker()->setUnknownNodeMarker();
const Type *RetTy = F->getFunctionType()->getReturnType();
if (const PointerType *PTy = dyn_cast<PointerType>(RetTy))
N->mergeTypeInfo(PTy->getElementType(), Result.getOffset());
}
// If this is freopen, merge the file descriptor passed in with the
// result.
if (F->getName() == "freopen") {
// ICC doesn't handle getting the iterator, decrementing and
// dereferencing it in one operation without error. Do it in 2 steps
CallSite::arg_iterator compit = CS.arg_end();
Result.mergeWith(getValueDest(**--compit));
}
return;
} else if (F->getName() == "fclose" && CS.arg_end()-CS.arg_begin() ==1){
// fclose reads and deallocates the memory in an unknown way for the
// file descriptor. It merges the FILE type into the descriptor.
DSNodeHandle H = getValueDest(**CS.arg_begin());
if (DSNode *N = H.getNode()) {
N->setReadMarker()->setUnknownNodeMarker();
const Type *ArgTy = F->getFunctionType()->getParamType(0);
if (const PointerType *PTy = dyn_cast<PointerType>(ArgTy))
N->mergeTypeInfo(PTy->getElementType(), H.getOffset());
}
return;
} else if (CS.arg_end()-CS.arg_begin() == 1 &&
(F->getName() == "fflush" || F->getName() == "feof" ||
F->getName() == "fileno" || F->getName() == "clearerr" ||
F->getName() == "rewind" || F->getName() == "ftell" ||
F->getName() == "ferror" || F->getName() == "fgetc" ||
F->getName() == "fgetc" || F->getName() == "_IO_getc")) {
// fflush reads and writes the memory for the file descriptor. It
// merges the FILE type into the descriptor.
DSNodeHandle H = getValueDest(**CS.arg_begin());
if (DSNode *N = H.getNode()) {
N->setReadMarker()->setModifiedMarker();
const Type *ArgTy = F->getFunctionType()->getParamType(0);
if (const PointerType *PTy = dyn_cast<PointerType>(ArgTy))
N->mergeTypeInfo(PTy->getElementType(), H.getOffset());
}
return;
} else if (CS.arg_end()-CS.arg_begin() == 4 &&
(F->getName() == "fwrite" || F->getName() == "fread")) {
// fread writes the first operand, fwrite reads it. They both
// read/write the FILE descriptor, and merges the FILE type.
CallSite::arg_iterator compit = CS.arg_end();
DSNodeHandle H = getValueDest(**--compit);
if (DSNode *N = H.getNode()) {
N->setReadMarker()->setModifiedMarker();
const Type *ArgTy = F->getFunctionType()->getParamType(3);
if (const PointerType *PTy = dyn_cast<PointerType>(ArgTy))
N->mergeTypeInfo(PTy->getElementType(), H.getOffset());
}
H = getValueDest(**CS.arg_begin());
if (DSNode *N = H.getNode())
if (F->getName() == "fwrite")
N->setReadMarker();
else
N->setModifiedMarker();
return;
} else if (F->getName() == "fgets" && CS.arg_end()-CS.arg_begin() == 3){
// fgets reads and writes the memory for the file descriptor. It
// merges the FILE type into the descriptor, and writes to the
// argument. It returns the argument as well.
CallSite::arg_iterator AI = CS.arg_begin();
DSNodeHandle H = getValueDest(**AI);
if (DSNode *N = H.getNode())
N->setModifiedMarker(); // Writes buffer
H.mergeWith(getValueDest(*CS.getInstruction())); // Returns buffer
++AI; ++AI;
// Reads and writes file descriptor, merge in FILE type.
H = getValueDest(**AI);
if (DSNode *N = H.getNode()) {
N->setReadMarker()->setModifiedMarker();
const Type *ArgTy = F->getFunctionType()->getParamType(2);
if (const PointerType *PTy = dyn_cast<PointerType>(ArgTy))
N->mergeTypeInfo(PTy->getElementType(), H.getOffset());
}
return;
} else if (F->getName() == "ungetc" || F->getName() == "fputc" ||
F->getName() == "fputs" || F->getName() == "putc" ||
F->getName() == "ftell" || F->getName() == "rewind" ||
F->getName() == "_IO_putc") {
// These functions read and write the memory for the file descriptor,
// which is passes as the last argument.
CallSite::arg_iterator compit = CS.arg_end();
DSNodeHandle H = getValueDest(**--compit);
if (DSNode *N = H.getNode()) {
N->setReadMarker()->setModifiedMarker();
FunctionType::param_iterator compit2 = F->getFunctionType()->param_end();
const Type *ArgTy = *--compit2;
if (const PointerType *PTy = dyn_cast<PointerType>(ArgTy))
N->mergeTypeInfo(PTy->getElementType(), H.getOffset());
}
// Any pointer arguments are read.
for (CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end();
AI != E; ++AI)
if (isPointerType((*AI)->getType()))
if (DSNode *N = getValueDest(**AI).getNode())
N->setReadMarker();
return;
} else if (F->getName() == "fseek" || F->getName() == "fgetpos" ||
F->getName() == "fsetpos") {
// These functions read and write the memory for the file descriptor,
// and read/write all other arguments.
DSNodeHandle H = getValueDest(**CS.arg_begin());
if (DSNode *N = H.getNode()) {
FunctionType::param_iterator compit2 = F->getFunctionType()->param_end();
const Type *ArgTy = *--compit2;
if (const PointerType *PTy = dyn_cast<PointerType>(ArgTy))
N->mergeTypeInfo(PTy->getElementType(), H.getOffset());
}
// Any pointer arguments are read.
for (CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end();
AI != E; ++AI)
if (isPointerType((*AI)->getType()))
if (DSNode *N = getValueDest(**AI).getNode())
N->setReadMarker()->setModifiedMarker();
return;
} else if (F->getName() == "printf" || F->getName() == "fprintf" ||
F->getName() == "sprintf") {
CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end();
if (F->getName() == "fprintf") {
// fprintf reads and writes the FILE argument, and applies the type
// to it.
DSNodeHandle H = getValueDest(**AI);
if (DSNode *N = H.getNode()) {
N->setModifiedMarker();
const Type *ArgTy = (*AI)->getType();
if (const PointerType *PTy = dyn_cast<PointerType>(ArgTy))
N->mergeTypeInfo(PTy->getElementType(), H.getOffset());
}
} else if (F->getName() == "sprintf") {
// sprintf writes the first string argument.
DSNodeHandle H = getValueDest(**AI++);
if (DSNode *N = H.getNode()) {
N->setModifiedMarker();
const Type *ArgTy = (*AI)->getType();
if (const PointerType *PTy = dyn_cast<PointerType>(ArgTy))
N->mergeTypeInfo(PTy->getElementType(), H.getOffset());
}
}
for (; AI != E; ++AI) {
// printf reads all pointer arguments.
if (isPointerType((*AI)->getType()))
if (DSNode *N = getValueDest(**AI).getNode())
N->setReadMarker();
}
return;
} else if (F->getName() == "vprintf" || F->getName() == "vfprintf" ||
F->getName() == "vsprintf") {
CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end();
if (F->getName() == "vfprintf") {
// ffprintf reads and writes the FILE argument, and applies the type
// to it.
DSNodeHandle H = getValueDest(**AI);
if (DSNode *N = H.getNode()) {
N->setModifiedMarker()->setReadMarker();
const Type *ArgTy = (*AI)->getType();
if (const PointerType *PTy = dyn_cast<PointerType>(ArgTy))
N->mergeTypeInfo(PTy->getElementType(), H.getOffset());
}
++AI;
} else if (F->getName() == "vsprintf") {
// vsprintf writes the first string argument.
DSNodeHandle H = getValueDest(**AI++);
if (DSNode *N = H.getNode()) {
N->setModifiedMarker();
const Type *ArgTy = (*AI)->getType();
if (const PointerType *PTy = dyn_cast<PointerType>(ArgTy))
N->mergeTypeInfo(PTy->getElementType(), H.getOffset());
}
}
// Read the format
if (AI != E) {
if (isPointerType((*AI)->getType()))
if (DSNode *N = getValueDest(**AI).getNode())
N->setReadMarker();
++AI;
}
// Read the valist, and the pointed-to objects.
if (AI != E && isPointerType((*AI)->getType())) {
const DSNodeHandle &VAList = getValueDest(**AI);
if (DSNode *N = VAList.getNode()) {
N->setReadMarker();
N->mergeTypeInfo(PointerType::get(Type::SByteTy),
VAList.getOffset(), false);
DSNodeHandle &VAListObjs = getLink(VAList);
VAListObjs.getNode()->setReadMarker();
}
}
return;
} else if (F->getName() == "scanf" || F->getName() == "fscanf" ||
F->getName() == "sscanf") {
CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end();
if (F->getName() == "fscanf") {
// fscanf reads and writes the FILE argument, and applies the type
// to it.
DSNodeHandle H = getValueDest(**AI);
if (DSNode *N = H.getNode()) {
N->setReadMarker();
const Type *ArgTy = (*AI)->getType();
if (const PointerType *PTy = dyn_cast<PointerType>(ArgTy))
N->mergeTypeInfo(PTy->getElementType(), H.getOffset());
}
} else if (F->getName() == "sscanf") {
// sscanf reads the first string argument.
DSNodeHandle H = getValueDest(**AI++);
if (DSNode *N = H.getNode()) {
N->setReadMarker();
const Type *ArgTy = (*AI)->getType();
if (const PointerType *PTy = dyn_cast<PointerType>(ArgTy))
N->mergeTypeInfo(PTy->getElementType(), H.getOffset());
}
}
for (; AI != E; ++AI) {
// scanf writes all pointer arguments.
if (isPointerType((*AI)->getType()))
if (DSNode *N = getValueDest(**AI).getNode())
N->setModifiedMarker();
}
return;
} else if (F->getName() == "strtok") {
// strtok reads and writes the first argument, returning it. It reads
// its second arg. FIXME: strtok also modifies some hidden static
// data. Someday this might matter.
CallSite::arg_iterator AI = CS.arg_begin();
DSNodeHandle H = getValueDest(**AI++);
if (DSNode *N = H.getNode()) {
N->setReadMarker()->setModifiedMarker(); // Reads/Writes buffer
const Type *ArgTy = F->getFunctionType()->getParamType(0);
if (const PointerType *PTy = dyn_cast<PointerType>(ArgTy))
N->mergeTypeInfo(PTy->getElementType(), H.getOffset());
}
H.mergeWith(getValueDest(*CS.getInstruction())); // Returns buffer
H = getValueDest(**AI); // Reads delimiter
if (DSNode *N = H.getNode()) {
N->setReadMarker();
const Type *ArgTy = F->getFunctionType()->getParamType(1);
if (const PointerType *PTy = dyn_cast<PointerType>(ArgTy))
N->mergeTypeInfo(PTy->getElementType(), H.getOffset());
}
return;
} else if (F->getName() == "strchr" || F->getName() == "strrchr" ||
F->getName() == "strstr") {
// These read their arguments, and return the first one
DSNodeHandle H = getValueDest(**CS.arg_begin());
H.mergeWith(getValueDest(*CS.getInstruction())); // Returns buffer
for (CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end();
AI != E; ++AI)
if (isPointerType((*AI)->getType()))
if (DSNode *N = getValueDest(**AI).getNode())
N->setReadMarker();
if (DSNode *N = H.getNode())
N->setReadMarker();
return;
} else if (F->getName() == "__assert_fail") {
for (CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end();
AI != E; ++AI)
if (isPointerType((*AI)->getType()))
if (DSNode *N = getValueDest(**AI).getNode())
N->setReadMarker();
return;
} else if (F->getName() == "modf" && CS.arg_end()-CS.arg_begin() == 2) {
// This writes its second argument, and forces it to double.
CallSite::arg_iterator compit = CS.arg_end();
DSNodeHandle H = getValueDest(**--compit);
if (DSNode *N = H.getNode()) {
N->setModifiedMarker();
N->mergeTypeInfo(Type::DoubleTy, H.getOffset());
}
return;
} else if (F->getName() == "strcat" || F->getName() == "strncat") {
//This might be making unsafe assumptions about usage
//Merge return and first arg
DSNodeHandle RetNH = getValueDest(*CS.getInstruction());
RetNH.mergeWith(getValueDest(**CS.arg_begin()));
if (DSNode *N = RetNH.getNode())
N->setHeapNodeMarker()->setModifiedMarker()->setReadMarker();
//and read second pointer
if (DSNode *N = getValueDest(**(CS.arg_begin() + 1)).getNode())
N->setReadMarker();
return;
} else {
// Unknown function, warn if it returns a pointer type or takes a
// pointer argument.
bool Warn = isPointerType(CS.getInstruction()->getType());
if (!Warn)
for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
I != E; ++I)
if (isPointerType((*I)->getType())) {
Warn = true;
break;
}
if (Warn)
std::cerr << "WARNING: Call to unknown external function '"
<< F->getName() << "' will cause pessimistic results!\n";
}
}
// Set up the return value...
DSNodeHandle RetVal;
Instruction *I = CS.getInstruction();
if (isPointerType(I->getType()))
RetVal = getValueDest(*I);
DSNode *CalleeNode = 0;
if (DisableDirectCallOpt || !isa<Function>(Callee)) {
CalleeNode = getValueDest(*Callee).getNode();
if (CalleeNode == 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 (CalleeNode)
FunctionCalls->push_back(DSCallSite(CS, RetVal, CalleeNode, Args));
else
FunctionCalls->push_back(DSCallSite(CS, RetVal, cast<Function>(Callee),
Args));
}
void GraphBuilder::visitFreeInst(FreeInst &FI) {
// Mark that the node is written to...
if (DSNode *N = getValueDest(*FI.getOperand(0)).getNode())
N->setModifiedMarker()->setHeapNodeMarker();
}
/// Handle casts...
void GraphBuilder::visitCastInst(CastInst &CI) {
if (isPointerType(CI.getType()))
if (isPointerType(CI.getOperand(0)->getType())) {
DSNodeHandle Ptr = getValueDest(*CI.getOperand(0));
if (Ptr.getNode() == 0) return;
// Cast one pointer to the other, just act like a copy instruction
setDestTo(CI, Ptr);
} 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 (DSNode *N = CurNode.getNode())
N->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...
DSNode *NHN = NH.getNode();
NHN->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;
}
const TargetData &TD = NH.getNode()->getTargetData();
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) {
DSNode *NHN = NH.getNode();
DSNodeHandle NewNH(NHN, NH.getOffset()+(unsigned)SL->MemberOffsets[i]);
MergeConstantInitIntoNode(NewNH, cast<Constant>(CS->getOperand(i)));
}
} else if (isa<ConstantAggregateZero>(C) || isa<UndefValue>(C)) {
// Noop
} 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());
}
/// BuildGlobalECs - Look at all of the nodes in the globals graph. If any node
/// contains multiple globals, DSA will never, ever, be able to tell the globals
/// apart. Instead of maintaining this information in all of the graphs
/// throughout the entire program, store only a single global (the "leader") in
/// the graphs, and build equivalence classes for the rest of the globals.
static void BuildGlobalECs(DSGraph &GG, std::set<GlobalValue*> &ECGlobals) {
DSScalarMap &SM = GG.getScalarMap();
EquivalenceClasses<GlobalValue*> &GlobalECs = SM.getGlobalECs();
for (DSGraph::node_iterator I = GG.node_begin(), E = GG.node_end();
I != E; ++I) {
if (I->getGlobalsList().size() <= 1) continue;
// First, build up the equivalence set for this block of globals.
const std::vector<GlobalValue*> &GVs = I->getGlobalsList();
GlobalValue *First = GVs[0];
for (unsigned i = 1, e = GVs.size(); i != e; ++i)
GlobalECs.unionSets(First, GVs[i]);
// Next, get the leader element.
assert(First == GlobalECs.getLeaderValue(First) &&
"First did not end up being the leader?");
// Next, remove all globals from the scalar map that are not the leader.
assert(GVs[0] == First && "First had to be at the front!");
for (unsigned i = 1, e = GVs.size(); i != e; ++i) {
ECGlobals.insert(GVs[i]);
SM.erase(SM.find(GVs[i]));
}
// Finally, change the global node to only contain the leader.
I->clearGlobals();
I->addGlobal(First);
}
DEBUG(GG.AssertGraphOK());
}
/// EliminateUsesOfECGlobals - Once we have determined that some globals are in
/// really just equivalent to some other globals, remove the globals from the
/// specified DSGraph (if present), and merge any nodes with their leader nodes.
static void EliminateUsesOfECGlobals(DSGraph &G,
const std::set<GlobalValue*> &ECGlobals) {
DSScalarMap &SM = G.getScalarMap();
EquivalenceClasses<GlobalValue*> &GlobalECs = SM.getGlobalECs();
bool MadeChange = false;
for (DSScalarMap::global_iterator GI = SM.global_begin(), E = SM.global_end();
GI != E; ) {
GlobalValue *GV = *GI++;
if (!ECGlobals.count(GV)) continue;
const DSNodeHandle &GVNH = SM[GV];
assert(!GVNH.isNull() && "Global has null NH!?");
// Okay, this global is in some equivalence class. Start by finding the
// leader of the class.
GlobalValue *Leader = GlobalECs.getLeaderValue(GV);
// If the leader isn't already in the graph, insert it into the node
// corresponding to GV.
if (!SM.global_count(Leader)) {
GVNH.getNode()->addGlobal(Leader);
SM[Leader] = GVNH;
} else {
// Otherwise, the leader is in the graph, make sure the nodes are the
// merged in the specified graph.
const DSNodeHandle &LNH = SM[Leader];
if (LNH.getNode() != GVNH.getNode())
LNH.mergeWith(GVNH);
}
// Next step, remove the global from the DSNode.
GVNH.getNode()->removeGlobal(GV);
// Finally, remove the global from the ScalarMap.
SM.erase(GV);
MadeChange = true;
}
DEBUG(if(MadeChange) G.AssertGraphOK());
}
bool LocalDataStructures::runOnModule(Module &M) {
const TargetData &TD = getAnalysis<TargetData>();
// First step, build the globals graph.
GlobalsGraph = new DSGraph(GlobalECs, TD);
{
GraphBuilder GGB(*GlobalsGraph);
// Add initializers for all of the globals to the globals graph.
for (Module::global_iterator I = M.global_begin(), E = M.global_end();
I != E; ++I)
if (!I->isExternal())
GGB.mergeInGlobalInitializer(I);
}
// Next step, iterate through the nodes in the globals graph, unioning
// together the globals into equivalence classes.
std::set<GlobalValue*> ECGlobals;
BuildGlobalECs(*GlobalsGraph, ECGlobals);
DEBUG(std::cerr << "Eliminating " << ECGlobals.size() << " EC Globals!\n");
ECGlobals.clear();
// 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(GlobalECs, TD, *I,
GlobalsGraph)));
GlobalsGraph->removeTriviallyDeadNodes();
GlobalsGraph->markIncompleteNodes(DSGraph::MarkFormalArgs);
// Now that we've computed all of the graphs, and merged all of the info into
// the globals graph, see if we have further constrained the globals in the
// program if so, update GlobalECs and remove the extraneous globals from the
// program.
BuildGlobalECs(*GlobalsGraph, ECGlobals);
if (!ECGlobals.empty()) {
DEBUG(std::cerr << "Eliminating " << ECGlobals.size() << " EC Globals!\n");
for (hash_map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
E = DSInfo.end(); I != E; ++I)
EliminateUsesOfECGlobals(*I->second, ECGlobals);
}
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;
}
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