llvm-6502/lib/Analysis/DataStructure/BottomUpClosure.cpp
2004-11-08 21:08:46 +00:00

334 lines
12 KiB
C++

//===- BottomUpClosure.cpp - Compute bottom-up interprocedural 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 BUDataStructures class, which represents the
// Bottom-Up Interprocedural closure of the data structure graph over the
// program. This is useful for applications like pool allocation, but **not**
// applications like alias analysis.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/DataStructure/DataStructure.h"
#include "llvm/Module.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Debug.h"
#include "DSCallSiteIterator.h"
using namespace llvm;
namespace {
Statistic<> MaxSCC("budatastructure", "Maximum SCC Size in Call Graph");
Statistic<> NumBUInlines("budatastructures", "Number of graphs inlined");
Statistic<> NumCallEdges("budatastructures", "Number of 'actual' call edges");
RegisterAnalysis<BUDataStructures>
X("budatastructure", "Bottom-up Data Structure Analysis");
}
using namespace DS;
// run - Calculate the bottom up data structure graphs for each function in the
// program.
//
bool BUDataStructures::runOnModule(Module &M) {
LocalDataStructures &LocalDSA = getAnalysis<LocalDataStructures>();
GlobalsGraph = new DSGraph(LocalDSA.getGlobalsGraph());
GlobalsGraph->setPrintAuxCalls();
Function *MainFunc = M.getMainFunction();
if (MainFunc)
calculateReachableGraphs(MainFunc);
// Calculate the graphs for any functions that are unreachable from main...
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
if (!I->isExternal() && !DSInfo.count(I)) {
#ifndef NDEBUG
if (MainFunc)
std::cerr << "*** Function unreachable from main: "
<< I->getName() << "\n";
#endif
calculateReachableGraphs(I); // Calculate all graphs...
}
NumCallEdges += ActualCallees.size();
// At the end of the bottom-up pass, the globals graph becomes complete.
// FIXME: This is not the right way to do this, but it is sorta better than
// nothing! In particular, externally visible globals and unresolvable call
// nodes at the end of the BU phase should make things that they point to
// incomplete in the globals graph.
//
GlobalsGraph->removeTriviallyDeadNodes();
GlobalsGraph->maskIncompleteMarkers();
return false;
}
void BUDataStructures::calculateReachableGraphs(Function *F) {
std::vector<Function*> Stack;
hash_map<Function*, unsigned> ValMap;
unsigned NextID = 1;
calculateGraphs(F, Stack, NextID, ValMap);
}
DSGraph &BUDataStructures::getOrCreateGraph(Function *F) {
// Has the graph already been created?
DSGraph *&Graph = DSInfo[F];
if (Graph) return *Graph;
// Copy the local version into DSInfo...
Graph = new DSGraph(getAnalysis<LocalDataStructures>().getDSGraph(*F));
Graph->setGlobalsGraph(GlobalsGraph);
Graph->setPrintAuxCalls();
// Start with a copy of the original call sites...
Graph->getAuxFunctionCalls() = Graph->getFunctionCalls();
return *Graph;
}
unsigned BUDataStructures::calculateGraphs(Function *F,
std::vector<Function*> &Stack,
unsigned &NextID,
hash_map<Function*, unsigned> &ValMap) {
assert(!ValMap.count(F) && "Shouldn't revisit functions!");
unsigned Min = NextID++, MyID = Min;
ValMap[F] = Min;
Stack.push_back(F);
// FIXME! This test should be generalized to be any function that we have
// already processed, in the case when there isn't a main or there are
// unreachable functions!
if (F->isExternal()) { // sprintf, fprintf, sscanf, etc...
// No callees!
Stack.pop_back();
ValMap[F] = ~0;
return Min;
}
DSGraph &Graph = getOrCreateGraph(F);
// The edges out of the current node are the call site targets...
for (DSCallSiteIterator I = DSCallSiteIterator::begin_aux(Graph),
E = DSCallSiteIterator::end_aux(Graph); I != E; ++I) {
Function *Callee = *I;
unsigned M;
// Have we visited the destination function yet?
hash_map<Function*, unsigned>::iterator It = ValMap.find(Callee);
if (It == ValMap.end()) // No, visit it now.
M = calculateGraphs(Callee, Stack, NextID, ValMap);
else // Yes, get it's number.
M = It->second;
if (M < Min) Min = M;
}
assert(ValMap[F] == MyID && "SCC construction assumption wrong!");
if (Min != MyID)
return Min; // This is part of a larger SCC!
// If this is a new SCC, process it now.
if (Stack.back() == F) { // Special case the single "SCC" case here.
DEBUG(std::cerr << "Visiting single node SCC #: " << MyID << " fn: "
<< F->getName() << "\n");
Stack.pop_back();
DSGraph &G = getDSGraph(*F);
DEBUG(std::cerr << " [BU] Calculating graph for: " << F->getName()<< "\n");
calculateGraph(G);
DEBUG(std::cerr << " [BU] Done inlining: " << F->getName() << " ["
<< G.getGraphSize() << "+" << G.getAuxFunctionCalls().size()
<< "]\n");
if (MaxSCC < 1) MaxSCC = 1;
// Should we revisit the graph?
if (DSCallSiteIterator::begin_aux(G) != DSCallSiteIterator::end_aux(G)) {
ValMap.erase(F);
return calculateGraphs(F, Stack, NextID, ValMap);
} else {
ValMap[F] = ~0U;
}
return MyID;
} else {
// SCCFunctions - Keep track of the functions in the current SCC
//
hash_set<DSGraph*> SCCGraphs;
Function *NF;
std::vector<Function*>::iterator FirstInSCC = Stack.end();
DSGraph *SCCGraph = 0;
do {
NF = *--FirstInSCC;
ValMap[NF] = ~0U;
// Figure out which graph is the largest one, in order to speed things up
// a bit in situations where functions in the SCC have widely different
// graph sizes.
DSGraph &NFGraph = getDSGraph(*NF);
SCCGraphs.insert(&NFGraph);
// FIXME: If we used a better way of cloning graphs (ie, just splice all
// of the nodes into the new graph), this would be completely unneeded!
if (!SCCGraph || SCCGraph->getGraphSize() < NFGraph.getGraphSize())
SCCGraph = &NFGraph;
} while (NF != F);
std::cerr << "Calculating graph for SCC #: " << MyID << " of size: "
<< SCCGraphs.size() << "\n";
// Compute the Max SCC Size...
if (MaxSCC < SCCGraphs.size())
MaxSCC = SCCGraphs.size();
// First thing first, collapse all of the DSGraphs into a single graph for
// the entire SCC. We computed the largest graph, so clone all of the other
// (smaller) graphs into it. Discard all of the old graphs.
//
for (hash_set<DSGraph*>::iterator I = SCCGraphs.begin(),
E = SCCGraphs.end(); I != E; ++I) {
DSGraph &G = **I;
if (&G != SCCGraph) {
{
DSGraph::NodeMapTy NodeMap;
SCCGraph->cloneInto(G, SCCGraph->getScalarMap(),
SCCGraph->getReturnNodes(), NodeMap);
}
// Update the DSInfo map and delete the old graph...
for (DSGraph::ReturnNodesTy::iterator I = G.getReturnNodes().begin(),
E = G.getReturnNodes().end(); I != E; ++I)
DSInfo[I->first] = SCCGraph;
delete &G;
}
}
// Clean up the graph before we start inlining a bunch again...
SCCGraph->removeDeadNodes(DSGraph::KeepUnreachableGlobals);
// Now that we have one big happy family, resolve all of the call sites in
// the graph...
calculateGraph(*SCCGraph);
DEBUG(std::cerr << " [BU] Done inlining SCC [" << SCCGraph->getGraphSize()
<< "+" << SCCGraph->getAuxFunctionCalls().size() << "]\n");
std::cerr << "DONE with SCC #: " << MyID << "\n";
// We never have to revisit "SCC" processed functions...
// Drop the stuff we don't need from the end of the stack
Stack.erase(FirstInSCC, Stack.end());
return MyID;
}
return MyID; // == Min
}
// releaseMemory - If the pass pipeline is done with this pass, we can release
// our memory... here...
//
void BUDataStructures::releaseMemory() {
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 BUDataStructures::calculateGraph(DSGraph &Graph) {
// Move our call site list into TempFCs so that inline call sites go into the
// new call site list and doesn't invalidate our iterators!
std::vector<DSCallSite> TempFCs;
std::vector<DSCallSite> &AuxCallsList = Graph.getAuxFunctionCalls();
TempFCs.swap(AuxCallsList);
DSGraph::ReturnNodesTy &ReturnNodes = Graph.getReturnNodes();
// Loop over all of the resolvable call sites
unsigned LastCallSiteIdx = ~0U;
for (DSCallSiteIterator I = DSCallSiteIterator::begin(TempFCs),
E = DSCallSiteIterator::end(TempFCs); I != E; ++I) {
// If we skipped over any call sites, they must be unresolvable, copy them
// to the real call site list.
LastCallSiteIdx++;
for (; LastCallSiteIdx < I.getCallSiteIdx(); ++LastCallSiteIdx)
AuxCallsList.push_back(TempFCs[LastCallSiteIdx]);
LastCallSiteIdx = I.getCallSiteIdx();
// Resolve the current call...
Function *Callee = *I;
DSCallSite CS = I.getCallSite();
if (Callee->isExternal()) {
// Ignore this case, simple varargs functions we cannot stub out!
} else if (ReturnNodes.count(Callee)) {
// Self recursion... simply link up the formal arguments with the
// actual arguments...
DEBUG(std::cerr << " Self Inlining: " << Callee->getName() << "\n");
// Handle self recursion by resolving the arguments and return value
Graph.mergeInGraph(CS, *Callee, Graph, 0);
} else {
ActualCallees.insert(std::make_pair(CS.getCallSite().getInstruction(),
Callee));
// Get the data structure graph for the called function.
//
DSGraph &GI = getDSGraph(*Callee); // Graph to inline
DEBUG(std::cerr << " Inlining graph for " << Callee->getName()
<< "[" << GI.getGraphSize() << "+"
<< GI.getAuxFunctionCalls().size() << "] into '"
<< Graph.getFunctionNames() << "' [" << Graph.getGraphSize() << "+"
<< Graph.getAuxFunctionCalls().size() << "]\n");
Graph.mergeInGraph(CS, *Callee, GI,
DSGraph::KeepModRefBits |
DSGraph::StripAllocaBit | DSGraph::DontCloneCallNodes);
++NumBUInlines;
#if 0
Graph.writeGraphToFile(std::cerr, "bu_" + F.getName() + "_after_" +
Callee->getName());
#endif
}
}
// Make sure to catch any leftover unresolvable calls...
for (++LastCallSiteIdx; LastCallSiteIdx < TempFCs.size(); ++LastCallSiteIdx)
AuxCallsList.push_back(TempFCs[LastCallSiteIdx]);
TempFCs.clear();
// Recompute the Incomplete markers
assert(Graph.getInlinedGlobals().empty());
Graph.maskIncompleteMarkers();
Graph.markIncompleteNodes(DSGraph::MarkFormalArgs);
// Delete dead nodes. Treat globals that are unreachable but that can
// reach live nodes as live.
Graph.removeDeadNodes(DSGraph::KeepUnreachableGlobals);
// When this graph is finalized, clone the globals in the graph into the
// globals graph to make sure it has everything, from all graphs.
DSScalarMap &MainSM = Graph.getScalarMap();
ReachabilityCloner RC(*GlobalsGraph, Graph, DSGraph::StripAllocaBit);
// Clone everything reachable from globals in the function graph into the
// globals graph.
for (DSScalarMap::global_iterator I = MainSM.global_begin(),
E = MainSM.global_end(); I != E; ++I)
RC.getClonedNH(MainSM[*I]);
//Graph.writeGraphToFile(std::cerr, "bu_" + F.getName());
}