llvm-6502/lib/Analysis/DataStructure/TopDownClosure.cpp
2006-11-17 07:33:59 +00:00

467 lines
17 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.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "td_dsa"
#include "llvm/Analysis/DataStructure/DataStructure.h"
#include "llvm/Module.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Analysis/DataStructure/DSGraph.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Timer.h"
#include "llvm/ADT/Statistic.h"
using namespace llvm;
#if 0
#define TIME_REGION(VARNAME, DESC) \
NamedRegionTimer VARNAME(DESC)
#else
#define TIME_REGION(VARNAME, DESC)
#endif
namespace {
RegisterPass<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()) {
std::vector<Function*> Functions;
NN->addFullFunctionList(Functions);
ArgsRemainIncomplete.insert(Functions.begin(), Functions.end());
markReachableFunctionsExternallyAccessible(NN, Visited);
}
}
}
// run - Calculate the top down data structure graphs for each function in the
// program.
//
bool TDDataStructures::runOnModule(Module &M) {
BUInfo = &getAnalysis<BUDataStructures>();
GlobalECs = BUInfo->getGlobalECs();
GlobalsGraph = new DSGraph(BUInfo->getGlobalsGraph(), GlobalECs);
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) {
DSNode *N = GGSM.find(*I)->second.getNode();
if (N->isIncomplete())
markReachableFunctionsExternallyAccessible(N, 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.
for (DSGraph::afc_iterator I = GlobalsGraph->afc_begin(),
E = GlobalsGraph->afc_end(); I != E; ++I)
for (unsigned arg = 0, e = I->getNumPtrArgs(); arg != e; ++arg)
markReachableFunctionsExternallyAccessible(I->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;
#if 0
{TIME_REGION(XXX, "td:Copy graphs");
// Visit each of the graphs in reverse post-order now!
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
if (!I->isExternal())
getOrCreateDSGraph(*I);
return false;
}
#endif
{TIME_REGION(XXX, "td:Compute postorder");
// Calculate top-down from main...
if (Function *F = M.getMainFunction())
ComputePostOrder(*F, VisitedGraph, PostOrder);
// Next calculate the graphs for each unreachable function...
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
ComputePostOrder(*I, VisitedGraph, PostOrder);
VisitedGraph.clear(); // Release memory!
}
{TIME_REGION(XXX, "td:Inline stuff");
// Visit each of the graphs in reverse post-order now!
while (!PostOrder.empty()) {
InlineCallersIntoGraph(*PostOrder.back());
PostOrder.pop_back();
}
}
// Free the IndCallMap.
while (!IndCallMap.empty()) {
delete IndCallMap.begin()->second;
IndCallMap.erase(IndCallMap.begin());
}
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), GlobalECs,
DSGraph::DontCloneAuxCallNodes);
assert(G->getAuxFunctionCalls().empty() && "Cloned aux calls?");
G->setPrintAuxCalls();
G->setGlobalsGraph(GlobalsGraph);
// Note that this graph is the graph for ALL of the function in the SCC, not
// just F.
for (DSGraph::retnodes_iterator RI = G->retnodes_begin(),
E = G->retnodes_end(); RI != E; ++RI)
if (RI->first != &F)
DSInfo[RI->first] = G;
}
return *G;
}
void TDDataStructures::ComputePostOrder(Function &F,hash_set<DSGraph*> &Visited,
std::vector<DSGraph*> &PostOrder) {
if (F.isExternal()) return;
DSGraph &G = getOrCreateDSGraph(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 (BUDataStructures::callee_iterator I = BUInfo->callee_begin(CallI),
E = BUInfo->callee_end(CallI); I != E; ++I)
ComputePostOrder(*I->second, Visited, PostOrder);
}
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;
}
/// InlineCallersIntoGraph - Inline all of the callers of the specified DS graph
/// into it, then recompute completeness of nodes in the resultant graph.
void TDDataStructures::InlineCallersIntoGraph(DSGraph &DSG) {
// Inline caller graphs into this graph. First step, get the list of call
// sites that call into this graph.
std::vector<CallerCallEdge> EdgesFromCaller;
std::map<DSGraph*, std::vector<CallerCallEdge> >::iterator
CEI = CallerEdges.find(&DSG);
if (CEI != CallerEdges.end()) {
std::swap(CEI->second, EdgesFromCaller);
CallerEdges.erase(CEI);
}
// Sort the caller sites to provide a by-caller-graph ordering.
std::sort(EdgesFromCaller.begin(), EdgesFromCaller.end());
// Merge information from the globals graph into this graph. FIXME: This is
// stupid. Instead of us cloning information from the GG into this graph,
// then having RemoveDeadNodes clone it back, we should do all of this as a
// post-pass over all of the graphs. We need to take cloning out of
// removeDeadNodes and gut removeDeadNodes at the same time first though. :(
{
DSGraph &GG = *DSG.getGlobalsGraph();
ReachabilityCloner RC(DSG, GG,
DSGraph::DontCloneCallNodes |
DSGraph::DontCloneAuxCallNodes);
for (DSScalarMap::global_iterator
GI = DSG.getScalarMap().global_begin(),
E = DSG.getScalarMap().global_end(); GI != E; ++GI)
RC.getClonedNH(GG.getNodeForValue(*GI));
}
DOUT << "[TD] Inlining callers into '" << DSG.getFunctionNames() << "'\n";
// Iteratively inline caller graphs into this graph.
while (!EdgesFromCaller.empty()) {
DSGraph &CallerGraph = *EdgesFromCaller.back().CallerGraph;
// Iterate through all of the call sites of this graph, cloning and merging
// any nodes required by the call.
ReachabilityCloner RC(DSG, CallerGraph,
DSGraph::DontCloneCallNodes |
DSGraph::DontCloneAuxCallNodes);
// Inline all call sites from this caller graph.
do {
const DSCallSite &CS = *EdgesFromCaller.back().CS;
Function &CF = *EdgesFromCaller.back().CalledFunction;
DOUT << " [TD] Inlining graph into Fn '" << CF.getName() << "' from ";
if (CallerGraph.getReturnNodes().empty())
DOUT << "SYNTHESIZED INDIRECT GRAPH";
else
DOUT << "Fn '" << CS.getCallSite().getInstruction()->
getParent()->getParent()->getName() << "'";
DOUT << ": " << CF.getFunctionType()->getNumParams() << " args\n";
// Get the formal argument and return nodes for the called function and
// merge them with the cloned subgraph.
DSCallSite T1 = DSG.getCallSiteForArguments(CF);
RC.mergeCallSite(T1, CS);
++NumTDInlines;
EdgesFromCaller.pop_back();
} while (!EdgesFromCaller.empty() &&
EdgesFromCaller.back().CallerGraph == &CallerGraph);
}
// Next, now that this graph is finalized, we need to recompute the
// incompleteness markers for this graph and remove unreachable nodes.
DSG.maskIncompleteMarkers();
// If any of the functions has incomplete incoming arguments, don't mark any
// of them as complete.
bool HasIncompleteArgs = false;
for (DSGraph::retnodes_iterator I = DSG.retnodes_begin(),
E = DSG.retnodes_end(); I != E; ++I)
if (ArgsRemainIncomplete.count(I->first)) {
HasIncompleteArgs = true;
break;
}
// Recompute the Incomplete markers. Depends on whether args are complete
unsigned Flags
= HasIncompleteArgs ? DSGraph::MarkFormalArgs : DSGraph::IgnoreFormalArgs;
DSG.markIncompleteNodes(Flags | DSGraph::IgnoreGlobals);
// Delete dead nodes. Treat globals that are unreachable as dead also.
DSG.removeDeadNodes(DSGraph::RemoveUnreachableGlobals);
// We are done with computing the current TD Graph! Finally, before we can
// finish processing this function, we figure out which functions it calls and
// records these call graph edges, so that we have them when we process the
// callee graphs.
if (DSG.fc_begin() == DSG.fc_end()) return;
// Loop over all the call sites and all the callees at each call site, and add
// edges to the CallerEdges structure for each callee.
for (DSGraph::fc_iterator CI = DSG.fc_begin(), E = DSG.fc_end();
CI != E; ++CI) {
// Handle direct calls efficiently.
if (CI->isDirectCall()) {
if (!CI->getCalleeFunc()->isExternal() &&
!DSG.getReturnNodes().count(CI->getCalleeFunc()))
CallerEdges[&getDSGraph(*CI->getCalleeFunc())]
.push_back(CallerCallEdge(&DSG, &*CI, CI->getCalleeFunc()));
continue;
}
Instruction *CallI = CI->getCallSite().getInstruction();
// For each function in the invoked function list at this call site...
BUDataStructures::callee_iterator IPI =
BUInfo->callee_begin(CallI), IPE = BUInfo->callee_end(CallI);
// Skip over all calls to this graph (SCC calls).
while (IPI != IPE && &getDSGraph(*IPI->second) == &DSG)
++IPI;
// All SCC calls?
if (IPI == IPE) continue;
Function *FirstCallee = IPI->second;
++IPI;
// Skip over more SCC calls.
while (IPI != IPE && &getDSGraph(*IPI->second) == &DSG)
++IPI;
// If there is exactly one callee from this call site, remember the edge in
// CallerEdges.
if (IPI == IPE) {
if (!FirstCallee->isExternal())
CallerEdges[&getDSGraph(*FirstCallee)]
.push_back(CallerCallEdge(&DSG, &*CI, FirstCallee));
continue;
}
// Otherwise, there are multiple callees from this call site, so it must be
// an indirect call. Chances are that there will be other call sites with
// this set of targets. If so, we don't want to do M*N inlining operations,
// so we build up a new, private, graph that represents the calls of all
// calls to this set of functions.
std::vector<Function*> Callees;
for (BUDataStructures::ActualCalleesTy::const_iterator I =
BUInfo->callee_begin(CallI), E = BUInfo->callee_end(CallI);
I != E; ++I)
if (!I->second->isExternal())
Callees.push_back(I->second);
std::sort(Callees.begin(), Callees.end());
std::map<std::vector<Function*>, DSGraph*>::iterator IndCallRecI =
IndCallMap.lower_bound(Callees);
DSGraph *IndCallGraph;
// If we already have this graph, recycle it.
if (IndCallRecI != IndCallMap.end() && IndCallRecI->first == Callees) {
DOUT << " [TD] *** Reuse of indcall graph for " << Callees.size()
<< " callees!\n";
IndCallGraph = IndCallRecI->second;
} else {
// Otherwise, create a new DSGraph to represent this.
IndCallGraph = new DSGraph(DSG.getGlobalECs(), DSG.getTargetData());
// Make a nullary dummy call site, which will eventually get some content
// merged into it. The actual callee function doesn't matter here, so we
// just pass it something to keep the ctor happy.
std::vector<DSNodeHandle> ArgDummyVec;
DSCallSite DummyCS(CI->getCallSite(), DSNodeHandle(), Callees[0]/*dummy*/,
ArgDummyVec);
IndCallGraph->getFunctionCalls().push_back(DummyCS);
IndCallRecI = IndCallMap.insert(IndCallRecI,
std::make_pair(Callees, IndCallGraph));
// Additionally, make sure that each of the callees inlines this graph
// exactly once.
DSCallSite *NCS = &IndCallGraph->getFunctionCalls().front();
for (unsigned i = 0, e = Callees.size(); i != e; ++i) {
DSGraph& CalleeGraph = getDSGraph(*Callees[i]);
if (&CalleeGraph != &DSG)
CallerEdges[&CalleeGraph].push_back(CallerCallEdge(IndCallGraph, NCS,
Callees[i]));
}
}
// Now that we know which graph to use for this, merge the caller
// information into the graph, based on information from the call site.
ReachabilityCloner RC(*IndCallGraph, DSG, 0);
RC.mergeCallSite(IndCallGraph->getFunctionCalls().front(), *CI);
}
}
static const Function *getFnForValue(const Value *V) {
if (const Instruction *I = dyn_cast<Instruction>(V))
return I->getParent()->getParent();
else if (const Argument *A = dyn_cast<Argument>(V))
return A->getParent();
else if (const BasicBlock *BB = dyn_cast<BasicBlock>(V))
return BB->getParent();
return 0;
}
void TDDataStructures::deleteValue(Value *V) {
if (const Function *F = getFnForValue(V)) { // Function local value?
// If this is a function local value, just delete it from the scalar map!
getDSGraph(*F).getScalarMap().eraseIfExists(V);
return;
}
if (Function *F = dyn_cast<Function>(V)) {
assert(getDSGraph(*F).getReturnNodes().size() == 1 &&
"cannot handle scc's");
delete DSInfo[F];
DSInfo.erase(F);
return;
}
assert(!isa<GlobalVariable>(V) && "Do not know how to delete GV's yet!");
}
void TDDataStructures::copyValue(Value *From, Value *To) {
if (From == To) return;
if (const Function *F = getFnForValue(From)) { // Function local value?
// If this is a function local value, just delete it from the scalar map!
getDSGraph(*F).getScalarMap().copyScalarIfExists(From, To);
return;
}
if (Function *FromF = dyn_cast<Function>(From)) {
Function *ToF = cast<Function>(To);
assert(!DSInfo.count(ToF) && "New Function already exists!");
DSGraph *NG = new DSGraph(getDSGraph(*FromF), GlobalECs);
DSInfo[ToF] = NG;
assert(NG->getReturnNodes().size() == 1 && "Cannot copy SCC's yet!");
// Change the Function* is the returnnodes map to the ToF.
DSNodeHandle Ret = NG->retnodes_begin()->second;
NG->getReturnNodes().clear();
NG->getReturnNodes()[ToF] = Ret;
return;
}
if (const Function *F = getFnForValue(To)) {
DSGraph &G = getDSGraph(*F);
G.getScalarMap().copyScalarIfExists(From, To);
return;
}
DOUT << *From;
DOUT << *To;
assert(0 && "Do not know how to copy this yet!");
abort();
}