llvm-6502/lib/Analysis/DataStructure/TopDownClosure.cpp
2004-07-07 06:32:21 +00:00

293 lines
12 KiB
C++

//===- TopDownClosure.cpp - Compute the top-down interprocedure closure ---===//
//
// 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.
//
//===----------------------------------------------------------------------===//
//
// 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/DataStructure.h"
#include "llvm/Module.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Analysis/DataStructure/DSGraph.h"
#include "Support/Debug.h"
#include "Support/Statistic.h"
using namespace llvm;
namespace {
RegisterAnalysis<TDDataStructures> // Register the pass
Y("tddatastructure", "Top-down Data Structure Analysis");
Statistic<> NumTDInlines("tddatastructures", "Number of graphs inlined");
}
void TDDataStructures::markReachableFunctionsExternallyAccessible(DSNode *N,
hash_set<DSNode*> &Visited) {
if (!N || Visited.count(N)) return;
Visited.insert(N);
for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i) {
DSNodeHandle &NH = N->getLink(i*N->getPointerSize());
if (DSNode *NN = NH.getNode()) {
const std::vector<GlobalValue*> &Globals = NN->getGlobals();
for (unsigned G = 0, e = Globals.size(); G != e; ++G)
if (Function *F = dyn_cast<Function>(Globals[G]))
ArgsRemainIncomplete.insert(F);
markReachableFunctionsExternallyAccessible(NN, Visited);
}
}
}
// 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());
GlobalsGraph->setPrintAuxCalls();
// Figure out which functions must not mark their arguments complete because
// they are accessible outside this compilation unit. Currently, these
// arguments are functions which are reachable by global variables in the
// globals graph.
const DSScalarMap &GGSM = GlobalsGraph->getScalarMap();
hash_set<DSNode*> Visited;
for (DSScalarMap::global_iterator I=GGSM.global_begin(), E=GGSM.global_end();
I != E; ++I)
markReachableFunctionsExternallyAccessible(GGSM.find(*I)->second.getNode(),
Visited);
// Loop over unresolved call nodes. Any functions passed into (but not
// returned!) from unresolvable call nodes may be invoked outside of the
// current module.
const std::vector<DSCallSite> &Calls = GlobalsGraph->getAuxFunctionCalls();
for (unsigned i = 0, e = Calls.size(); i != e; ++i) {
const DSCallSite &CS = Calls[i];
for (unsigned arg = 0, e = CS.getNumPtrArgs(); arg != e; ++arg)
markReachableFunctionsExternallyAccessible(CS.getPtrArg(arg).getNode(),
Visited);
}
Visited.clear();
// Functions without internal linkage also have unknown incoming arguments!
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
if (!I->isExternal() && !I->hasInternalLinkage())
ArgsRemainIncomplete.insert(I);
// We want to traverse the call graph in reverse post-order. To do this, we
// calculate a post-order traversal, then reverse it.
hash_set<DSGraph*> VisitedGraph;
std::vector<DSGraph*> PostOrder;
const BUDataStructures::ActualCalleesTy &ActualCallees =
getAnalysis<BUDataStructures>().getActualCallees();
// Calculate top-down from main...
if (Function *F = M.getMainFunction())
ComputePostOrder(*F, VisitedGraph, PostOrder, ActualCallees);
// Next calculate the graphs for each unreachable function...
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
ComputePostOrder(*I, VisitedGraph, PostOrder, ActualCallees);
VisitedGraph.clear(); // Release memory!
// Visit each of the graphs in reverse post-order now!
while (!PostOrder.empty()) {
inlineGraphIntoCallees(*PostOrder.back());
PostOrder.pop_back();
}
ArgsRemainIncomplete.clear();
GlobalsGraph->removeTriviallyDeadNodes();
return false;
}
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;
}
void TDDataStructures::ComputePostOrder(Function &F,hash_set<DSGraph*> &Visited,
std::vector<DSGraph*> &PostOrder,
const BUDataStructures::ActualCalleesTy &ActualCallees) {
if (F.isExternal()) return;
DSGraph &G = getOrCreateDSGraph(F);
if (Visited.count(&G)) return;
Visited.insert(&G);
// Recursively traverse all of the callee graphs.
const std::vector<DSCallSite> &FunctionCalls = G.getFunctionCalls();
for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i) {
Instruction *CallI = FunctionCalls[i].getCallSite().getInstruction();
std::pair<BUDataStructures::ActualCalleesTy::const_iterator,
BUDataStructures::ActualCalleesTy::const_iterator>
IP = ActualCallees.equal_range(CallI);
for (BUDataStructures::ActualCalleesTy::const_iterator I = IP.first;
I != IP.second; ++I)
ComputePostOrder(*I->second, Visited, PostOrder, ActualCallees);
}
PostOrder.push_back(&G);
}
// 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;
}
void TDDataStructures::inlineGraphIntoCallees(DSGraph &Graph) {
// Recompute the Incomplete markers and eliminate unreachable nodes.
Graph.maskIncompleteMarkers();
// If any of the functions has incomplete incoming arguments, don't mark any
// of them as complete.
bool HasIncompleteArgs = false;
const DSGraph::ReturnNodesTy &GraphReturnNodes = Graph.getReturnNodes();
for (DSGraph::ReturnNodesTy::const_iterator I = GraphReturnNodes.begin(),
E = GraphReturnNodes.end(); I != E; ++I)
if (ArgsRemainIncomplete.count(I->first)) {
HasIncompleteArgs = true;
break;
}
// Now fold in the necessary globals from the GlobalsGraph. A global G
// must be folded in if it exists in the current graph (i.e., is not dead)
// and it was not inlined from any of my callers. If it was inlined from
// a caller, it would have been fully consistent with the GlobalsGraph
// in the caller so folding in is not necessary. Otherwise, this node came
// solely from this function's BU graph and so has to be made consistent.
//
Graph.updateFromGlobalGraph();
// Recompute the Incomplete markers. Depends on whether args are complete
unsigned Flags
= HasIncompleteArgs ? DSGraph::MarkFormalArgs : DSGraph::IgnoreFormalArgs;
Graph.markIncompleteNodes(Flags | DSGraph::IgnoreGlobals);
// Delete dead nodes. Treat globals that are unreachable as dead also.
Graph.removeDeadNodes(DSGraph::RemoveUnreachableGlobals);
// We are done with computing the current TD Graph! Now move on to
// inlining the current graph into the graphs for its callees, if any.
//
const std::vector<DSCallSite> &FunctionCalls = Graph.getFunctionCalls();
if (FunctionCalls.empty()) {
DEBUG(std::cerr << " [TD] No callees for: " << Graph.getFunctionNames()
<< "\n");
return;
}
// Now that we have information about all of the callees, propagate the
// current graph into the callees. Clone only the reachable subgraph at
// each call-site, not the entire graph (even though the entire graph
// would be cloned only once, this should still be better on average).
//
DEBUG(std::cerr << " [TD] Inlining '" << Graph.getFunctionNames() <<"' into "
<< FunctionCalls.size() << " call nodes.\n");
const BUDataStructures::ActualCalleesTy &ActualCallees =
getAnalysis<BUDataStructures>().getActualCallees();
// Loop over all the call sites and all the callees at each call site. Build
// a mapping from called DSGraph's to the call sites in this function that
// invoke them. This is useful because we can be more efficient if there are
// multiple call sites to the callees in the graph from this caller.
std::multimap<DSGraph*, std::pair<Function*, const DSCallSite*> > CallSites;
for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i) {
Instruction *CallI = FunctionCalls[i].getCallSite().getInstruction();
// For each function in the invoked function list at this call site...
std::pair<BUDataStructures::ActualCalleesTy::const_iterator,
BUDataStructures::ActualCalleesTy::const_iterator>
IP = ActualCallees.equal_range(CallI);
// Loop over each actual callee at this call site
for (BUDataStructures::ActualCalleesTy::const_iterator I = IP.first;
I != IP.second; ++I) {
DSGraph& CalleeGraph = getDSGraph(*I->second);
assert(&CalleeGraph != &Graph && "TD need not inline graph into self!");
CallSites.insert(std::make_pair(&CalleeGraph,
std::make_pair(I->second, &FunctionCalls[i])));
}
}
// Now that we built the mapping, actually perform the inlining a callee graph
// at a time.
std::multimap<DSGraph*,std::pair<Function*,const DSCallSite*> >::iterator CSI;
for (CSI = CallSites.begin(); CSI != CallSites.end(); ) {
DSGraph &CalleeGraph = *CSI->first;
// Iterate through all of the call sites of this graph, cloning and merging
// any nodes required by the call.
ReachabilityCloner RC(CalleeGraph, Graph, DSGraph::StripModRefBits);
// Clone over any global nodes that appear in both graphs.
for (DSScalarMap::global_iterator
SI = CalleeGraph.getScalarMap().global_begin(),
SE = CalleeGraph.getScalarMap().global_end(); SI != SE; ++SI) {
DSScalarMap::const_iterator GI = Graph.getScalarMap().find(*SI);
if (GI != Graph.getScalarMap().end())
RC.merge(CalleeGraph.getNodeForValue(*SI), GI->second);
}
// Loop over all of the distinct call sites in the caller of the callee.
for (; CSI != CallSites.end() && CSI->first == &CalleeGraph; ++CSI) {
Function &CF = *CSI->second.first;
const DSCallSite &CS = *CSI->second.second;
DEBUG(std::cerr << " [TD] Resolving arguments for callee graph '"
<< CalleeGraph.getFunctionNames()
<< "': " << CF.getFunctionType()->getNumParams()
<< " args\n at call site (DSCallSite*) 0x" << &CS << "\n");
// Get the formal argument and return nodes for the called function and
// merge them with the cloned subgraph.
RC.mergeCallSite(CalleeGraph.getCallSiteForArguments(CF), CS);
++NumTDInlines;
}
}
DEBUG(std::cerr << " [TD] Done inlining into callees for: "
<< Graph.getFunctionNames() << " [" << Graph.getGraphSize() << "+"
<< Graph.getFunctionCalls().size() << "]\n");
}