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llvm-mirror/lib/Analysis/DataStructure/EquivClassGraphs.cpp
2006-08-27 22:30:17 +00:00

484 lines
18 KiB
C++

//===- EquivClassGraphs.cpp - Merge equiv-class graphs & inline bottom-up -===//
//
// 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 pass is the same as the complete bottom-up graphs, but
// with functions partitioned into equivalence classes and a single merged
// DS graph for all functions in an equivalence class. After this merging,
// graphs are inlined bottom-up on the SCCs of the final (CBU) call graph.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "ECGraphs"
#include "llvm/Analysis/DataStructure/DataStructure.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/DataStructure/DSGraph.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/SCCIterator.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/EquivalenceClasses.h"
#include "llvm/ADT/STLExtras.h"
#include <iostream>
using namespace llvm;
namespace {
RegisterPass<EquivClassGraphs> X("eqdatastructure",
"Equivalence-class Bottom-up Data Structure Analysis");
Statistic<> NumEquivBUInlines("equivdatastructures",
"Number of graphs inlined");
Statistic<> NumFoldGraphInlines("Inline equiv-class graphs bottom up",
"Number of graphs inlined");
}
#ifndef NDEBUG
template<typename GT>
static void CheckAllGraphs(Module *M, GT &ECGraphs) {
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
if (!I->isExternal()) {
DSGraph &G = ECGraphs.getDSGraph(*I);
if (G.retnodes_begin()->first != I)
continue; // Only check a graph once.
DSGraph::NodeMapTy GlobalsGraphNodeMapping;
G.computeGToGGMapping(GlobalsGraphNodeMapping);
}
}
#endif
// getSomeCalleeForCallSite - Return any one callee function at a call site.
//
Function *EquivClassGraphs::getSomeCalleeForCallSite(const CallSite &CS) const{
Function *thisFunc = CS.getCaller();
assert(thisFunc && "getSomeCalleeForCallSite(): Not a valid call site?");
DSGraph &DSG = getDSGraph(*thisFunc);
DSNode *calleeNode = DSG.getNodeForValue(CS.getCalledValue()).getNode();
std::map<DSNode*, Function *>::const_iterator I =
OneCalledFunction.find(calleeNode);
return (I == OneCalledFunction.end())? NULL : I->second;
}
// runOnModule - Calculate the bottom up data structure graphs for each function
// in the program.
//
bool EquivClassGraphs::runOnModule(Module &M) {
CBU = &getAnalysis<CompleteBUDataStructures>();
GlobalECs = CBU->getGlobalECs();
DEBUG(CheckAllGraphs(&M, *CBU));
GlobalsGraph = new DSGraph(CBU->getGlobalsGraph(), GlobalECs);
GlobalsGraph->setPrintAuxCalls();
ActualCallees = CBU->getActualCallees();
// Find equivalence classes of functions called from common call sites.
// Fold the CBU graphs for all functions in an equivalence class.
buildIndirectFunctionSets(M);
// Stack of functions used for Tarjan's SCC-finding algorithm.
std::vector<DSGraph*> Stack;
std::map<DSGraph*, unsigned> ValMap;
unsigned NextID = 1;
Function *MainFunc = M.getMainFunction();
if (MainFunc && !MainFunc->isExternal()) {
processSCC(getOrCreateGraph(*MainFunc), Stack, NextID, ValMap);
} else {
std::cerr << "Fold Graphs: No 'main' function found!\n";
}
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
if (!I->isExternal())
processSCC(getOrCreateGraph(*I), Stack, NextID, ValMap);
DEBUG(CheckAllGraphs(&M, *this));
getGlobalsGraph().removeTriviallyDeadNodes();
getGlobalsGraph().markIncompleteNodes(DSGraph::IgnoreGlobals);
// Merge the globals variables (not the calls) from the globals graph back
// into the main function's graph so that the main function contains all of
// the information about global pools and GV usage in the program.
if (MainFunc && !MainFunc->isExternal()) {
DSGraph &MainGraph = getOrCreateGraph(*MainFunc);
const DSGraph &GG = *MainGraph.getGlobalsGraph();
ReachabilityCloner RC(MainGraph, GG,
DSGraph::DontCloneCallNodes |
DSGraph::DontCloneAuxCallNodes);
// Clone the global nodes into this graph.
for (DSScalarMap::global_iterator I = GG.getScalarMap().global_begin(),
E = GG.getScalarMap().global_end(); I != E; ++I)
if (isa<GlobalVariable>(*I))
RC.getClonedNH(GG.getNodeForValue(*I));
MainGraph.maskIncompleteMarkers();
MainGraph.markIncompleteNodes(DSGraph::MarkFormalArgs |
DSGraph::IgnoreGlobals);
}
// Final processing. Note that dead node elimination may actually remove
// globals from a function graph that are immediately used. If there are no
// scalars pointing to the node (e.g. because the only use is a direct store
// to a scalar global) we have to make sure to rematerialize the globals back
// into the graphs here, or clients will break!
for (Module::global_iterator GI = M.global_begin(), E = M.global_end();
GI != E; ++GI)
// This only happens to first class typed globals.
if (GI->getType()->getElementType()->isFirstClassType())
for (Value::use_iterator UI = GI->use_begin(), E = GI->use_end();
UI != E; ++UI)
// This only happens to direct uses by instructions.
if (Instruction *User = dyn_cast<Instruction>(*UI)) {
DSGraph &DSG = getOrCreateGraph(*User->getParent()->getParent());
if (!DSG.getScalarMap().count(GI)) {
// If this global does not exist in the graph, but it is immediately
// used by an instruction in the graph, clone it over from the
// globals graph.
ReachabilityCloner RC(DSG, *GlobalsGraph, 0);
RC.getClonedNH(GlobalsGraph->getNodeForValue(GI));
}
}
return false;
}
// buildIndirectFunctionSets - Iterate over the module looking for indirect
// calls to functions. If a call site can invoke any functions [F1, F2... FN],
// unify the N functions together in the FuncECs set.
//
void EquivClassGraphs::buildIndirectFunctionSets(Module &M) {
const ActualCalleesTy& AC = CBU->getActualCallees();
// Loop over all of the indirect calls in the program. If a call site can
// call multiple different functions, we need to unify all of the callees into
// the same equivalence class.
Instruction *LastInst = 0;
Function *FirstFunc = 0;
for (ActualCalleesTy::const_iterator I=AC.begin(), E=AC.end(); I != E; ++I) {
if (I->second->isExternal())
continue; // Ignore functions we cannot modify
CallSite CS = CallSite::get(I->first);
if (CS.getCalledFunction()) { // Direct call:
FuncECs.insert(I->second); // -- Make sure function has equiv class
FirstFunc = I->second; // -- First callee at this site
} else { // Else indirect call
// DEBUG(std::cerr << "CALLEE: " << I->second->getName()
// << " from : " << I->first);
if (I->first != LastInst) {
// This is the first callee from this call site.
LastInst = I->first;
FirstFunc = I->second;
// Instead of storing the lastInst For Indirection call Sites we store
// the DSNode for the function ptr arguemnt
Function *thisFunc = LastInst->getParent()->getParent();
DSGraph &TFG = CBU->getDSGraph(*thisFunc);
DSNode *calleeNode = TFG.getNodeForValue(CS.getCalledValue()).getNode();
OneCalledFunction[calleeNode] = FirstFunc;
FuncECs.insert(I->second);
} else {
// This is not the first possible callee from a particular call site.
// Union the callee in with the other functions.
FuncECs.unionSets(FirstFunc, I->second);
#ifndef NDEBUG
Function *thisFunc = LastInst->getParent()->getParent();
DSGraph &TFG = CBU->getDSGraph(*thisFunc);
DSNode *calleeNode = TFG.getNodeForValue(CS.getCalledValue()).getNode();
assert(OneCalledFunction.count(calleeNode) > 0 && "Missed a call?");
#endif
}
}
// Now include all functions that share a graph with any function in the
// equivalence class. More precisely, if F is in the class, and G(F) is
// its graph, then we include all other functions that are also in G(F).
// Currently, that is just the functions in the same call-graph-SCC as F.
//
DSGraph& funcDSGraph = CBU->getDSGraph(*I->second);
for (DSGraph::retnodes_iterator RI = funcDSGraph.retnodes_begin(),
RE = funcDSGraph.retnodes_end(); RI != RE; ++RI)
FuncECs.unionSets(FirstFunc, RI->first);
}
// Now that all of the equivalences have been built, merge the graphs for
// each equivalence class.
//
DEBUG(std::cerr << "\nIndirect Function Equivalence Sets:\n");
for (EquivalenceClasses<Function*>::iterator EQSI = FuncECs.begin(), E =
FuncECs.end(); EQSI != E; ++EQSI) {
if (!EQSI->isLeader()) continue;
EquivalenceClasses<Function*>::member_iterator SI =
FuncECs.member_begin(EQSI);
assert(SI != FuncECs.member_end() && "Empty equiv set??");
EquivalenceClasses<Function*>::member_iterator SN = SI;
++SN;
if (SN == FuncECs.member_end())
continue; // Single function equivalence set, no merging to do.
Function* LF = *SI;
#ifndef NDEBUG
DEBUG(std::cerr <<" Equivalence set for leader " << LF->getName() <<" = ");
for (SN = SI; SN != FuncECs.member_end(); ++SN)
DEBUG(std::cerr << " " << (*SN)->getName() << "," );
DEBUG(std::cerr << "\n");
#endif
// This equiv class has multiple functions: merge their graphs. First,
// clone the CBU graph for the leader and make it the common graph for the
// equivalence graph.
DSGraph &MergedG = getOrCreateGraph(*LF);
// Record the argument nodes for use in merging later below.
std::vector<DSNodeHandle> ArgNodes;
for (Function::arg_iterator AI = LF->arg_begin(), E = LF->arg_end();
AI != E; ++AI)
if (DS::isPointerType(AI->getType()))
ArgNodes.push_back(MergedG.getNodeForValue(AI));
// Merge in the graphs of all other functions in this equiv. class. Note
// that two or more functions may have the same graph, and it only needs
// to be merged in once.
std::set<DSGraph*> GraphsMerged;
GraphsMerged.insert(&CBU->getDSGraph(*LF));
for (++SI; SI != FuncECs.member_end(); ++SI) {
Function *F = *SI;
DSGraph *&FG = DSInfo[F];
DSGraph &CBUGraph = CBU->getDSGraph(*F);
if (GraphsMerged.insert(&CBUGraph).second) {
// Record the "folded" graph for the function.
for (DSGraph::retnodes_iterator I = CBUGraph.retnodes_begin(),
E = CBUGraph.retnodes_end(); I != E; ++I) {
assert(DSInfo[I->first] == 0 && "Graph already exists for Fn!");
DSInfo[I->first] = &MergedG;
}
// Clone this member of the equivalence class into MergedG.
MergedG.cloneInto(CBUGraph);
}
// Merge the return nodes of all functions together.
MergedG.getReturnNodes()[LF].mergeWith(MergedG.getReturnNodes()[F]);
// Merge the function arguments with all argument nodes found so far.
// If there are extra function args, add them to the vector of argNodes
Function::arg_iterator AI2 = F->arg_begin(), AI2end = F->arg_end();
for (unsigned arg = 0, numArgs = ArgNodes.size();
arg != numArgs && AI2 != AI2end; ++AI2, ++arg)
if (DS::isPointerType(AI2->getType()))
ArgNodes[arg].mergeWith(MergedG.getNodeForValue(AI2));
for ( ; AI2 != AI2end; ++AI2)
if (DS::isPointerType(AI2->getType()))
ArgNodes.push_back(MergedG.getNodeForValue(AI2));
DEBUG(MergedG.AssertGraphOK());
}
}
DEBUG(std::cerr << "\n");
}
DSGraph &EquivClassGraphs::getOrCreateGraph(Function &F) {
// Has the graph already been created?
DSGraph *&Graph = DSInfo[&F];
if (Graph) return *Graph;
DSGraph &CBUGraph = CBU->getDSGraph(F);
// Copy the CBU graph...
Graph = new DSGraph(CBUGraph, GlobalECs); // updates the map via reference
Graph->setGlobalsGraph(&getGlobalsGraph());
Graph->setPrintAuxCalls();
// Make sure to update the DSInfo map for all functions in the graph!
for (DSGraph::retnodes_iterator I = Graph->retnodes_begin();
I != Graph->retnodes_end(); ++I)
if (I->first != &F) {
DSGraph *&FG = DSInfo[I->first];
assert(FG == 0 && "Merging function in SCC twice?");
FG = Graph;
}
return *Graph;
}
unsigned EquivClassGraphs::
processSCC(DSGraph &FG, std::vector<DSGraph*> &Stack, unsigned &NextID,
std::map<DSGraph*, unsigned> &ValMap) {
std::map<DSGraph*, unsigned>::iterator It = ValMap.lower_bound(&FG);
if (It != ValMap.end() && It->first == &FG)
return It->second;
DEBUG(std::cerr << " ProcessSCC for function " << FG.getFunctionNames()
<< "\n");
unsigned Min = NextID++, MyID = Min;
ValMap[&FG] = Min;
Stack.push_back(&FG);
// The edges out of the current node are the call site targets...
for (DSGraph::fc_iterator CI = FG.fc_begin(), CE = FG.fc_end();
CI != CE; ++CI) {
Instruction *Call = CI->getCallSite().getInstruction();
// Loop over all of the actually called functions...
for (callee_iterator I = callee_begin(Call), E = callee_end(Call);
I != E; ++I)
if (!I->second->isExternal()) {
// Process the callee as necessary.
unsigned M = processSCC(getOrCreateGraph(*I->second),
Stack, NextID, ValMap);
if (M < Min) Min = M;
}
}
assert(ValMap[&FG] == 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.
bool MergedGraphs = false;
while (Stack.back() != &FG) {
DSGraph *NG = Stack.back();
ValMap[NG] = ~0U;
// If the SCC found is not the same as those found in CBU, make sure to
// merge the graphs as appropriate.
FG.cloneInto(*NG);
// Update the DSInfo map and delete the old graph...
for (DSGraph::retnodes_iterator I = NG->retnodes_begin();
I != NG->retnodes_end(); ++I)
DSInfo[I->first] = &FG;
// Remove NG from the ValMap since the pointer may get recycled.
ValMap.erase(NG);
delete NG;
MergedGraphs = true;
Stack.pop_back();
}
// Clean up the graph before we start inlining a bunch again.
if (MergedGraphs)
FG.removeTriviallyDeadNodes();
Stack.pop_back();
processGraph(FG);
ValMap[&FG] = ~0U;
return MyID;
}
/// processGraph - Process the CBU graphs for the program in bottom-up order on
/// the SCC of the __ACTUAL__ call graph. This builds final folded CBU graphs.
void EquivClassGraphs::processGraph(DSGraph &G) {
DEBUG(std::cerr << " ProcessGraph for function "
<< G.getFunctionNames() << "\n");
hash_set<Instruction*> calls;
// Else we need to inline some callee graph. Visit all call sites.
// The edges out of the current node are the call site targets...
unsigned i = 0;
for (DSGraph::fc_iterator CI = G.fc_begin(), CE = G.fc_end(); CI != CE;
++CI, ++i) {
const DSCallSite &CS = *CI;
Instruction *TheCall = CS.getCallSite().getInstruction();
assert(calls.insert(TheCall).second &&
"Call instruction occurs multiple times in graph??");
if (CS.getRetVal().isNull() && CS.getNumPtrArgs() == 0)
continue;
// Inline the common callee graph into the current graph, if the callee
// graph has not changed. Note that all callees should have the same
// graph so we only need to do this once.
//
DSGraph* CalleeGraph = NULL;
callee_iterator I = callee_begin(TheCall), E = callee_end(TheCall);
unsigned TNum, Num;
// Loop over all potential callees to find the first non-external callee.
for (TNum = 0, Num = std::distance(I, E); I != E; ++I, ++TNum)
if (!I->second->isExternal())
break;
// Now check if the graph has changed and if so, clone and inline it.
if (I != E) {
Function *CalleeFunc = I->second;
// Merge the callee's graph into this graph, if not already the same.
// Callees in the same equivalence class (which subsumes those
// in the same SCCs) have the same graph. Note that all recursion
// including self-recursion have been folded in the equiv classes.
//
CalleeGraph = &getOrCreateGraph(*CalleeFunc);
if (CalleeGraph != &G) {
++NumFoldGraphInlines;
G.mergeInGraph(CS, *CalleeFunc, *CalleeGraph,
DSGraph::StripAllocaBit |
DSGraph::DontCloneCallNodes |
DSGraph::DontCloneAuxCallNodes);
DEBUG(std::cerr << " Inlining graph [" << i << "/"
<< G.getFunctionCalls().size()-1
<< ":" << TNum << "/" << Num-1 << "] for "
<< CalleeFunc->getName() << "["
<< CalleeGraph->getGraphSize() << "+"
<< CalleeGraph->getAuxFunctionCalls().size()
<< "] into '" /*<< G.getFunctionNames()*/ << "' ["
<< G.getGraphSize() << "+" << G.getAuxFunctionCalls().size()
<< "]\n");
}
}
#ifndef NDEBUG
// Now loop over the rest of the callees and make sure they have the
// same graph as the one inlined above.
if (CalleeGraph)
for (++I, ++TNum; I != E; ++I, ++TNum)
if (!I->second->isExternal())
assert(CalleeGraph == &getOrCreateGraph(*I->second) &&
"Callees at a call site have different graphs?");
#endif
}
// Recompute the Incomplete markers.
G.maskIncompleteMarkers();
G.markIncompleteNodes(DSGraph::MarkFormalArgs);
// Delete dead nodes. Treat globals that are unreachable but that can
// reach live nodes as live.
G.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.
ReachabilityCloner RC(*G.getGlobalsGraph(), G, DSGraph::StripAllocaBit);
// Clone everything reachable from globals in the function graph into the
// globals graph.
DSScalarMap &MainSM = G.getScalarMap();
for (DSScalarMap::global_iterator I = MainSM.global_begin(),
E = MainSM.global_end(); I != E; ++I)
RC.getClonedNH(MainSM[*I]);
DEBUG(std::cerr << " -- DONE ProcessGraph for function "
<< G.getFunctionNames() << "\n");
}