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//===- TopDownClosure.cpp - Compute the top-down interprocedure closure ---===//
//
// This file implements the TDDataStructures class, which represents the
// Top-down Interprocedural closure of the data structure graph over the
// program. This is useful (but not strictly necessary?) for applications
// like pointer analysis.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/DataStructure.h"
#include "llvm/Analysis/DSGraph.h"
#include "llvm/Module.h"
#include "llvm/DerivedTypes.h"
#include "Support/Statistic.h"
namespace {
RegisterAnalysis<TDDataStructures> // Register the pass
Y("tddatastructure", "Top-down Data Structure Analysis");
}
// run - Calculate the top down data structure graphs for each function in the
// program.
//
bool TDDataStructures::run(Module &M) {
BUDataStructures &BU = getAnalysis<BUDataStructures>();
GlobalsGraph = new DSGraph(BU.getGlobalsGraph());
// Calculate top-down from main...
if (Function *F = M.getMainFunction())
calculateGraph(*F);
// Next calculate the graphs for each function unreachable function...
for (Module::reverse_iterator I = M.rbegin(), E = M.rend(); I != E; ++I)
if (!I->isExternal())
calculateGraph(*I);
GraphDone.clear(); // Free temporary memory...
return false;
}
// releaseMemory - If the pass pipeline is done with this pass, we can release
// our memory... here...
//
// FIXME: This should be releaseMemory and will work fine, except that LoadVN
// has no way to extend the lifetime of the pass, which screws up ds-aa.
//
void TDDataStructures::releaseMyMemory() {
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;
}
#if 0
/// ResolveCallSite - This method is used to link the actual arguments together
/// with the formal arguments for a function call in the top-down closure. This
/// method assumes that the call site arguments have been mapped into nodes
/// local to the specified graph.
///
void TDDataStructures::ResolveCallSite(DSGraph &Graph,
const DSCallSite &CallSite) {
// Resolve all of the function formal arguments...
Function &F = Graph.getFunction();
Function::aiterator AI = F.abegin();
for (unsigned i = 0, e = CallSite.getNumPtrArgs(); i != e; ++i, ++AI) {
// Advance the argument iterator to the first pointer argument...
while (!DS::isPointerType(AI->getType())) ++AI;
// TD ...Merge the formal arg scalar with the actual arg node
DSNodeHandle &NodeForFormal = Graph.getNodeForValue(AI);
assert(NodeForFormal.getNode() && "Pointer argument has no dest node!");
NodeForFormal.mergeWith(CallSite.getPtrArg(i));
}
// Merge returned node in the caller with the "return" node in callee
if (CallSite.getRetVal().getNode() && Graph.getRetNode().getNode())
Graph.getRetNode().mergeWith(CallSite.getRetVal());
}
#endif
DSGraph &TDDataStructures::getOrCreateDSGraph(Function &F) {
DSGraph *&G = DSInfo[&F];
if (G == 0) { // Not created yet? Clone BU graph...
G = new DSGraph(getAnalysis<BUDataStructures>().getDSGraph(F));
G->getAuxFunctionCalls().clear();
G->setPrintAuxCalls();
G->setGlobalsGraph(GlobalsGraph);
}
return *G;
}
/// FunctionHasCompleteArguments - This function returns true if it is safe not
/// to mark arguments to the function complete.
///
/// FIXME: Need to check if all callers have been found, or rather if a
/// funcpointer escapes!
///
static bool FunctionHasCompleteArguments(Function &F) {
return F.hasInternalLinkage();
}
void TDDataStructures::calculateGraph(Function &F) {
// Make sure this graph has not already been calculated, and that we don't get
// into an infinite loop with mutually recursive functions.
//
if (GraphDone.count(&F)) return;
GraphDone.insert(&F);
// Get the current functions graph...
DSGraph &Graph = getOrCreateDSGraph(F);
// Recompute the Incomplete markers and eliminate unreachable nodes.
Graph.maskIncompleteMarkers();
unsigned Flags = FunctionHasCompleteArguments(F) ?
DSGraph::IgnoreFormalArgs : DSGraph::MarkFormalArgs;
Graph.markIncompleteNodes(Flags | DSGraph::IgnoreGlobals);
Graph.removeDeadNodes(DSGraph::RemoveUnreachableGlobals);
const std::vector<DSCallSite> &CallSites = Graph.getFunctionCalls();
if (CallSites.empty()) {
DEBUG(std::cerr << " [TD] No callees for: " << F.getName() << "\n");
} else {
// Loop over all of the call sites, building a multi-map from Callees to
// DSCallSite*'s. With this map we can then loop over each callee, cloning
// this graph once into it, then resolving arguments.
//
std::multimap<Function*, const DSCallSite*> CalleeSites;
for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
const DSCallSite &CS = CallSites[i];
if (CS.isDirectCall()) {
if (!CS.getCalleeFunc()->isExternal()) // If it's not external
CalleeSites.insert(std::make_pair(CS.getCalleeFunc(), &CS));// Keep it
} else {
const std::vector<GlobalValue*> &Callees =
CS.getCalleeNode()->getGlobals();
// Loop over all of the functions that this call may invoke...
for (unsigned c = 0, e = Callees.size(); c != e; ++c)
if (Function *F = dyn_cast<Function>(Callees[c]))// If this is a fn...
if (!F->isExternal()) // If it's not extern
CalleeSites.insert(std::make_pair(F, &CS)); // Keep track of it!
}
}
// Now that we have information about all of the callees, propagate the
// current graph into the callees.
//
DEBUG(std::cerr << " [TD] Inlining '" << F.getName() << "' into "
<< CalleeSites.size() << " callees.\n");
// Loop over all the callees...
for (std::multimap<Function*, const DSCallSite*>::iterator
I = CalleeSites.begin(), E = CalleeSites.end(); I != E; )
if (I->first == &F) { // Bottom-up pass takes care of self loops!
++I;
} else {
// For each callee...
Function &Callee = *I->first;
DSGraph &CG = getOrCreateDSGraph(Callee); // Get the callee's graph...
DEBUG(std::cerr << "\t [TD] Inlining into callee '" << Callee.getName()
<< "'\n");
// Clone our current graph into the callee...
DSGraph::ScalarMapTy OldValMap;
DSGraph::NodeMapTy OldNodeMap;
DSGraph::ReturnNodesTy ReturnNodes;
CG.cloneInto(Graph, OldValMap, ReturnNodes, OldNodeMap,
DSGraph::StripModRefBits |
DSGraph::KeepAllocaBit | DSGraph::DontCloneCallNodes |
DSGraph::DontCloneAuxCallNodes);
OldValMap.clear(); // We don't care about the ValMap
ReturnNodes.clear(); // We don't care about return values either
// Loop over all of the invocation sites of the callee, resolving
// arguments to our graph. This loop may iterate multiple times if the
// current function calls this callee multiple times with different
// signatures.
//
for (; I != E && I->first == &Callee; ++I) {
// Map call site into callee graph
DSCallSite NewCS(*I->second, OldNodeMap);
// Resolve the return values...
NewCS.getRetVal().mergeWith(CG.getReturnNodeFor(Callee));
// Resolve all of the arguments...
Function::aiterator AI = Callee.abegin();
for (unsigned i = 0, e = NewCS.getNumPtrArgs();
i != e && AI != Callee.aend(); ++i, ++AI) {
// Advance the argument iterator to the first pointer argument...
while (AI != Callee.aend() && !DS::isPointerType(AI->getType()))
++AI;
if (AI == Callee.aend()) break;
// Add the link from the argument scalar to the provided value
DSNodeHandle &NH = CG.getNodeForValue(AI);
assert(NH.getNode() && "Pointer argument without scalarmap entry?");
NH.mergeWith(NewCS.getPtrArg(i));
}
}
// Done with the nodemap...
OldNodeMap.clear();
// Recompute the Incomplete markers and eliminate unreachable nodes.
CG.removeTriviallyDeadNodes();
CG.maskIncompleteMarkers();
CG.markIncompleteNodes(DSGraph::MarkFormalArgs |DSGraph::IgnoreGlobals);
CG.removeDeadNodes(DSGraph::RemoveUnreachableGlobals);
}
DEBUG(std::cerr << " [TD] Done inlining into callees for: " << F.getName()
<< " [" << Graph.getGraphSize() << "+"
<< Graph.getFunctionCalls().size() << "]\n");
// Loop over all the callees... making sure they are all resolved now...
Function *LastFunc = 0;
for (std::multimap<Function*, const DSCallSite*>::iterator
I = CalleeSites.begin(), E = CalleeSites.end(); I != E; ++I)
if (I->first != LastFunc) { // Only visit each callee once...
LastFunc = I->first;
calculateGraph(*I->first);
}
}
}
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