void TDDataStructures::ComputePostOrder(const Function* F,
hash_set<DSGraph*> &Visited,
std::vector<DSGraph*> &PostOrder) {
if (F->isDeclaration()) return;
DSGraph* G = getOrFetchDSGraph(F);
if (Visited.count(G)) return;
Visited.insert(G);
// Recursively traverse all of the callee graphs.
for (DSGraph::fc_iterator CI = G->fc_begin(), CE = G->fc_end(); CI != CE; ++CI){
Instruction *CallI = CI->getCallSite().getInstruction();
for (calleeTy::iterator I = callee.begin(CallI),
E = callee.end(CallI); I != E; ++I)
ComputePostOrder(*I, Visited, PostOrder);
}
PostOrder.push_back(G);
}
void TDDataStructures::ComputePostOrder(const Function &F,
DenseSet<DSGraph*> &Visited,
std::vector<DSGraph*> &PostOrder) {
if (F.isDeclaration()) return;
DSGraph* G = getOrCreateGraph(&F);
if (!Visited.insert(G).second) return;
// Recursively traverse all of the callee graphs.
svset<const Function*> Callees;
// Go through all of the callsites in this graph and find all callees
// Here we're trying to capture all possible callees so that we can ensure
// each function has all possible callers inlined into it.
for (DSGraph::fc_iterator CI = G->fc_begin(), E = G->fc_end();
CI != E; ++CI) {
// Direct calls are easy, no reason to look at DSCallGraph
// or anything to do with SCC's
if (CI->isDirectCall()) {
ComputePostOrder(*CI->getCalleeFunc(), Visited, PostOrder);
}
else {
// Otherwise, ask the DSCallGraph for the full set of possible
// callees for this callsite.
// This includes all members of the SCC's of those callees,
// and well as others in F's SCC, since we must assume
// any indirect call might be intra-SCC.
callgraph.addFullFunctionSet(CI->getCallSite(), Callees);
}
}
for (svset<const Function*>::iterator I = Callees.begin(),
E = Callees.end(); I != E; ++I)
ComputePostOrder(**I, Visited, PostOrder);
PostOrder.push_back(G);
}
/// visitGraph - Visit the functions in the specified graph, updating the
/// specified lattice values for all of their uses.
///
void StructureFieldVisitorBase::
visitGraph(DSGraph &DSG, std::multimap<DSNode*, LatticeValue*> &NodeLVs) {
assert(!NodeLVs.empty() && "No lattice values to compute!");
// To visit a graph, first step, we visit the instruction making up each
// function in the graph, but ignore calls when processing them. We handle
// call nodes explicitly by looking at call nodes in the graph if needed. We
// handle instructions before calls to avoid interprocedural analysis if we
// can drive lattice values to bottom early.
//
SFVInstVisitor IV(DSG, Callbacks, NodeLVs);
for (DSGraph::retnodes_iterator FI = DSG.retnodes_begin(),
E = DSG.retnodes_end(); FI != E; ++FI)
for (Function::iterator BB = FI->first->begin(), E = FI->first->end();
BB != E; ++BB)
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
if (IV.visit(*I) && NodeLVs.empty())
return; // Nothing left to analyze.
// Keep track of which actual direct callees are handled.
std::set<Function*> CalleesHandled;
// Once we have visited all of the instructions in the function bodies, if
// there are lattice values that have not been driven to bottom, see if any of
// the nodes involved are passed into function calls. If so, we potentially
// have to recursively traverse the call graph.
for (DSGraph::fc_iterator CS = DSG.fc_begin(), E = DSG.fc_end();
CS != E; ++CS) {
// Figure out the mapping from a node in the caller (potentially several)
// nodes in the callee.
DSGraph::NodeMapTy CallNodeMap;
Instruction *TheCall = CS->getCallSite().getInstruction();
// If this is an indirect function call, assume nothing gets passed through
// it. FIXME: THIS IS BROKEN! Just get the ECG for the fn ptr if it's not
// direct.
if (CS->isIndirectCall())
continue;
// If this is an external function call, it cannot be involved with this
// node, because otherwise the node would be marked incomplete!
if (CS->getCalleeFunc()->isExternal())
continue;
// If we can handle this function call, remove it from the set of direct
// calls found by the visitor.
CalleesHandled.insert(CS->getCalleeFunc());
std::vector<DSNodeHandle> Args;
DSGraph *CG = &ECG.getDSGraph(*CS->getCalleeFunc());
CG->getFunctionArgumentsForCall(CS->getCalleeFunc(), Args);
if (!CS->getRetVal().isNull())
DSGraph::computeNodeMapping(Args[0], CS->getRetVal(), CallNodeMap);
for (unsigned i = 0, e = CS->getNumPtrArgs(); i != e; ++i) {
if (i == Args.size()-1) break;
DSGraph::computeNodeMapping(Args[i+1], CS->getPtrArg(i), CallNodeMap);
}
Args.clear();
// The mapping we just computed maps from nodes in the callee to nodes in
// the caller, so we can't query it efficiently. Instead of going through
// the trouble of inverting the map to do this (linear time with the size of
// the mapping), we just do a linear search to see if any affected nodes are
// passed into this call.
bool CallCanModifyDataFlow = false;
for (DSGraph::NodeMapTy::iterator MI = CallNodeMap.begin(),
E = CallNodeMap.end(); MI != E; ++MI)
if (NodeLVs.count(MI->second.getNode()))
// Okay, the node is passed in, check to see if the call might do
// something interesting to it (i.e. if analyzing the call can produce
// anything other than "top").
if ((CallCanModifyDataFlow = NodeCanPossiblyBeInteresting(MI->first,
Callbacks)))
break;
// If this function call cannot impact the analysis (either because the
// nodes we are tracking are not passed into the call, or the DSGraph for
// the callee tells us that analysis of the callee can't provide interesting
// information), ignore it.
if (!CallCanModifyDataFlow)
continue;
// Okay, either compute analysis results for the callee function, or reuse
// results previously computed.
std::multimap<DSNode*, LatticeValue*> &CalleeFacts = getCalleeFacts(*CG);
// Merge all of the facts for the callee into the facts for the caller. If
// this reduces anything in the caller to 'bottom', remove them.
for (DSGraph::NodeMapTy::iterator MI = CallNodeMap.begin(),
E = CallNodeMap.end(); MI != E; ++MI) {
// If we have Lattice facts in the caller for this node in the callee,
// merge any information from the callee into the caller.
// If the node is not accessed in the callee at all, don't update.
if (MI->first->getType() == Type::VoidTy)
continue;
// If there are no data-flow facts live in the caller for this node, don't
// both processing it.
std::multimap<DSNode*, LatticeValue*>::iterator NLVI =
NodeLVs.find(MI->second.getNode());
if (NLVI == NodeLVs.end()) continue;
// Iterate over all of the lattice values that have corresponding fields
// in the callee, merging in information as we go. Be careful about the
// fact that the callee may get passed the address of a substructure and
// other funny games.
//if (CalleeFacts.count(const_cast<DSNode*>(MI->first)) == 0) {
DSNode *CalleeNode = const_cast<DSNode*>(MI->first);
unsigned CalleeNodeOffset = MI->second.getOffset();
while (NLVI->first == MI->second.getNode()) {
// Figure out what offset in the callee this field would land.
unsigned FieldOff = NLVI->second->getFieldOffset()+CalleeNodeOffset;
// If the field is not within the callee node, ignore it.
if (FieldOff >= CalleeNode->getSize()) {
++NLVI;
continue;
}
// Okay, check to see if we have a lattice value for the field at offset
// FieldOff in the callee node.
const LatticeValue *CalleeLV = 0;
std::multimap<DSNode*, LatticeValue*>::iterator CFI =
CalleeFacts.lower_bound(CalleeNode);
for (; CFI != CalleeFacts.end() && CFI->first == CalleeNode; ++CFI)
if (CFI->second->getFieldOffset() == FieldOff) {
CalleeLV = CFI->second; // Found it!
break;
}
// If we don't, the lattice value hit bottom and we should remove the
// lattice value in the caller.
if (!CalleeLV) {
delete NLVI->second; // The lattice value hit bottom.
NodeLVs.erase(NLVI++);
continue;
}
// Finally, if we did find a corresponding entry, merge the information
// into the caller's lattice value and keep going.
if (NLVI->second->mergeInValue(CalleeLV)) {
// Okay, merging these two caused the caller value to hit bottom.
// Remove it.
delete NLVI->second; // The lattice value hit bottom.
NodeLVs.erase(NLVI++);
}
++NLVI; // We successfully merged in some information!
}
// If we ran out of facts to prove, just exit.
if (NodeLVs.empty()) return;
}
}
// The local analysis pass inconveniently discards many local function calls
// from the graph if they are to known functions. Loop over direct function
// calls not handled above and visit them as appropriate.
while (!IV.DirectCallSites.empty()) {
Instruction *Call = *IV.DirectCallSites.begin();
IV.DirectCallSites.erase(IV.DirectCallSites.begin());
// Is this one actually handled by DSA?
if (CalleesHandled.count(cast<Function>(Call->getOperand(0))))
continue;
// Collect the pointers involved in this call.
std::vector<Value*> Pointers;
if (isa<PointerType>(Call->getType()))
Pointers.push_back(Call);
for (unsigned i = 1, e = Call->getNumOperands(); i != e; ++i)
if (isa<PointerType>(Call->getOperand(i)->getType()))
Pointers.push_back(Call->getOperand(i));
// If this is an intrinsic function call, figure out which one.
unsigned IID = cast<Function>(Call->getOperand(0))->getIntrinsicID();
for (unsigned i = 0, e = Pointers.size(); i != e; ++i) {
// If any of our lattice values are passed into this call, which is
// specially handled by the local analyzer, inform the lattice function.
DSNode *N = DSG.getNodeForValue(Pointers[i]).getNode();
for (std::multimap<DSNode*, LatticeValue*>::iterator LVI =
NodeLVs.lower_bound(N); LVI != NodeLVs.end() && LVI->first == N;) {
bool AtBottom = false;
switch (IID) {
default:
AtBottom = LVI->second->visitRecognizedCall(*Call);
break;
case Intrinsic::memset:
if (Callbacks & Visit::Stores)
AtBottom = LVI->second->visitMemSet(*cast<CallInst>(Call));
break;
}
if (AtBottom) {
delete LVI->second;
NodeLVs.erase(LVI++);
} else {
++LVI;
}
}
}
}
}
