// Method: getDSNodeHandle()
//
// Description:
// This method looks up the DSNodeHandle for a given LLVM value. The context
// of the value is the specified function, although if it is a global value,
// the DSNodeHandle may exist within the global DSGraph.
//
// Return value:
// A DSNodeHandle for the value is returned. This DSNodeHandle could either
// be in the function's DSGraph or from the GlobalsGraph. Note that the
// DSNodeHandle may represent a NULL DSNode.
//
template<class dsa> DSNodeHandle
TypeSafety<dsa>::getDSNodeHandle (const Value * V, const Function * F) {
//
// Ensure that the function has a DSGraph
//
assert (dsaPass->hasDSGraph(*F) && "No DSGraph for function!\n");
//
// Lookup the DSNode for the value in the function's DSGraph.
//
const DSGraph * TDG = dsaPass->getDSGraph(*F);
DSNodeHandle DSH;
if(TDG->hasNodeForValue(V))
DSH = TDG->getNodeForValue(V);
//
// If the value wasn't found in the function's DSGraph, then maybe we can
// find the value in the globals graph.
//
if ((DSH.isNull()) && (isa<GlobalValue>(V))) {
//
// Try looking up this DSNode value in the globals graph. Note that
// globals are put into equivalence classes; we may need to first find the
// equivalence class to which our global belongs, find the global that
// represents all globals in that equivalence class, and then look up the
// DSNode Handle for *that* global.
//
DSH = getDSNodeHandle(cast<GlobalValue>(V));
}
return DSH;
}
//
// Function: makeFSParameterCallsComplete()
//
// Description:
// Finds calls to sc.fsparameter and fills in the completeness byte which
// is the last argument to such call. The second argument to the function
// is the one which is analyzed for completeness.
//
// Inputs:
// M - Reference to the the module to analyze
//
void
CompleteChecks::makeFSParameterCallsComplete(Module &M)
{
Function *sc_fsparameter = M.getFunction("sc.fsparameter");
if (sc_fsparameter == NULL)
return;
std::set<CallInst *> toComplete;
//
// Iterate over all uses of sc.fsparameter and discover which have a complete
// pointer argument.
//
for (Function::use_iterator i = sc_fsparameter->use_begin();
i != sc_fsparameter->use_end(); ++i) {
CallInst *CI;
CI = dyn_cast<CallInst>(*i);
if (CI == 0 || CI->getCalledFunction() != sc_fsparameter)
continue;
//
// Get the parent function to which this call belongs.
//
Function *P = CI->getParent()->getParent();
Value *PtrOperand = CI->getOperand(2);
DSNode *N = getDSNodeHandle(PtrOperand, P).getNode();
if (N == 0 ||
N->isExternalNode() ||
N->isIncompleteNode() ||
N->isUnknownNode() ||
N->isPtrToIntNode() ||
N->isIntToPtrNode()) {
continue;
}
toComplete.insert(CI);
}
//
// Fill in a 1 for each call instruction that has a complete pointer
// argument.
//
Type *int8 = Type::getInt8Ty(M.getContext());
Constant *complete = ConstantInt::get(int8, 1);
for (std::set<CallInst *>::iterator i = toComplete.begin();
i != toComplete.end();
++i) {
CallInst *CI = *i;
CI->setOperand(4, complete);
}
return;
}
//
// TODO
//
template<class dsa> bool
TypeSafety<dsa>::isFieldDisjoint (const GlobalValue * V, unsigned offset) {
//
// Get the DSNode for the specified value.
//
DSNodeHandle DH = getDSNodeHandle (V);
DSNode *node = DH.getNode();
//unsigned offset = DH.getOffset();
DEBUG(errs() << " check fields overlap at: " << offset << "\n");
//
// If there is no DSNode, claim that it is not type safe.
//
if (DH.isNull()) {
return false;
}
//
// If the DSNode is completely folded, then we know for sure that it is not
// type-safe.
//
if (node->isNodeCompletelyFolded())
return false;
//
// If the memory object represented by this DSNode can be manipulated by
// external code or DSA has otherwise not finished analyzing all operations
// on it, declare it type-unsafe.
//
if (node->isExternalNode() || node->isIncompleteNode())
return false;
//
// If the pointer to the memory object came from some source not understood
// by DSA or somehow came from/escapes to the realm of integers, declare it
// type-unsafe.
//
if (node->isUnknownNode() || node->isIntToPtrNode() || node->isPtrToIntNode()) {
return false;
}
return !((NodeInfo[node])[offset]);
}
template<class dsa> bool
TypeSafety<dsa>::isTypeSafe(const GlobalValue *V) {
//
// Get the DSNode for the specified value.
//
DSNodeHandle DH = getDSNodeHandle(V);
//
// If there is no DSNode, claim that it is not typesafe.
//
if (DH.isNull())
return false;
//
// See if the DSNode is one that we think is type-safe.
//
if (TypeSafeNodes.count (DH.getNode()))
return true;
return false;
}
//
// Function: makeComplete()
//
// Description:
// Find run-time checks on memory objects for which we have complete analysis
// information and change them into complete functions.
//
// Inputs:
// M - A reference to the module to modify.
// CheckInfo - Information about the run-time check.
//
// Outputs:
// M - The module is modified so that incomplete checks are changed to
// complete checks if necessary.
//
void
CompleteChecks::makeComplete (Module & M, const struct CheckInfo & CheckInfo) {
//
// Get the run-time checking functions.
//
Function * Complete = M.getFunction (CheckInfo.completeName);
Function * Incomplete = M.getFunction (CheckInfo.name);
//
// If the incomplete function does not exist within the module, then don't
// do anything.
//
if (!Incomplete)
return;
//
// If the complete version of the function does not exist, then create it.
//
if (!Complete) {
FunctionType * FT = Incomplete->getFunctionType();
Complete=cast<Function>(M.getOrInsertFunction (CheckInfo.completeName, FT));
}
//
// Scan through all uses of the run-time check and record any checks on
// complete pointers.
//
std::vector <CallInst *> toChange;
Value::use_iterator UI = Incomplete->use_begin();
Value::use_iterator E = Incomplete->use_end();
for (; UI != E; ++UI) {
if (CallInst * CI = dyn_cast<CallInst>(*UI)) {
if (CI->getCalledValue()->stripPointerCasts() == Incomplete) {
//
// Get the pointer that is checked by this run-time check.
//
Value * CheckPtr = CheckInfo.getCheckedPointer (CI);
//
// If the pointer is complete, then change the check.
//
Function * F = CI->getParent()->getParent();
if (DSNode * N = getDSNodeHandle (CheckPtr, F).getNode()) {
if (!(N->isExternalNode() ||
N->isIncompleteNode() ||
N->isUnknownNode() ||
N->isIntToPtrNode() ||
N->isPtrToIntNode())) {
toChange.push_back (CI);
}
}
}
}
}
//
// Update statistics. Note that we only assign if the value is non-zero;
// this prevents the statistics from being reported if the value is zero.
//
if (toChange.size())
CompLSChecks += toChange.size();
//
// Now iterate through all of the call sites and transform them to be
// complete.
//
for (unsigned index = 0; index < toChange.size(); ++index) {
toChange[index]->setCalledFunction (Complete);
}
return;
}
//
// Function: makeCStdLibCallsComplete()
//
// Description:
// Fills in completeness information for all calls of a given CStdLib function
// assumed to be of the form:
//
// pool_X(POOL *p1, ..., POOL *pN, void *a1, ..., void *aN, ..., uint8_t c);
//
// Specifically, this function assumes that there are as many pointer arguments
// to check as there are initial pool arguments, and the pointer arguments
// follow the pool arguments in corresponding order. Also, it is assumed that
// the final argument to the function is a byte sized bit vector.
//
// This function fills in this final byte with a constant value whose ith
// bit is set exactly when the ith pointer argument is complete.
//
// Inputs:
//
// F - A pointer to the CStdLib function appearing in the module
// (non-null).
// PoolArgs - The number of initial pool arguments for which a
// corresponding pointer value requires a completeness check
// (required to be at most 8).
//
void
CompleteChecks::makeCStdLibCallsComplete(Function *F, unsigned PoolArgs) {
assert(F != 0 && "Null function argument!");
assert(PoolArgs <= 8 && \
"Only up to 8 arguments are supported by CStdLib completeness checks!");
Value::use_iterator U = F->use_begin();
Value::use_iterator E = F->use_end();
//
// Hold the call instructions that need changing.
//
typedef std::pair<CallInst *, uint8_t> VectorReplacement;
std::set<VectorReplacement> callsToChange;
Type *int8ty = Type::getInt8Ty(F->getContext());
FunctionType *F_type = F->getFunctionType();
//
// Verify the type of the function is as expected.
//
// There should be as many pointer parameters to check for completeness
// as there are pool parameters. The last parameter should be a byte.
//
assert(F_type->getNumParams() >= PoolArgs * 2 && \
"Not enough arguments to transformed CStdLib function call!");
for (unsigned arg = PoolArgs; arg < PoolArgs * 2; ++arg)
assert(isa<PointerType>(F_type->getParamType(arg)) && \
"Expected pointer argument to function!");
//
// This is the position of the vector operand in the call.
//
unsigned vect_position = F_type->getNumParams();
assert(F_type->getParamType(vect_position - 1) == int8ty && \
"Last parameter to the function should be a byte!");
//
// Iterate over all calls of the function in the module, computing the
// vectors for each call as it is found.
//
for (; U != E; ++U) {
CallInst *CI;
if ((CI = dyn_cast<CallInst>(*U)) && \
CI->getCalledValue()->stripPointerCasts() == F) {
uint8_t vector = 0x0;
//
// Get the parent function to which this instruction belongs.
//
Function *P = CI->getParent()->getParent();
//
// Iterate over the pointer arguments that need completeness checking
// and build the completeness vector.
//
for (unsigned arg = 0; arg < PoolArgs; ++arg) {
bool complete = true;
//
// Go past all the pool arguments to get the pointer to check.
//
Value *V = CI->getOperand(1 + PoolArgs + arg);
//
// Check for completeness of the pointer using DSA and
// set the bit in the vector accordingly.
//
DSNode *N;
if ((N = getDSNodeHandle(V, P).getNode()) &&
(N->isExternalNode() || N->isIncompleteNode() ||
N->isUnknownNode() || N->isIntToPtrNode() ||
N->isPtrToIntNode()) ) {
complete = false;
}
if (complete)
vector |= (1 << arg);
}
//
// Add the instruction and vector to the set of instructions to change.
//
callsToChange.insert(VectorReplacement(CI, vector));
}
}
//
// Iterate over all call instructions that need changing, modifying the
// final operand of the call to hold the bit vector value.
//
std::set<VectorReplacement>::iterator change = callsToChange.begin();
std::set<VectorReplacement>::iterator change_end = callsToChange.end();
while (change != change_end) {
Constant *vect_value = ConstantInt::get(int8ty, change->second);
change->first->setOperand(vect_position, vect_value);
++change;
}
return;
}
