llvm/lib/Analysis/IPA/IPModRef.cpp
Chris Lattner 923fc05b3a Implement optimization for direct function call case. This dramatically
reduces the number of function nodes created and speeds up analysis by
about 10% overall.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5495 91177308-0d34-0410-b5e6-96231b3b80d8
2003-02-05 21:59:58 +00:00

440 lines
15 KiB
C++

//===- IPModRef.cpp - Compute IP Mod/Ref information ------------*- C++ -*-===//
//
// See high-level comments in include/llvm/Analysis/IPModRef.h
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/IPModRef.h"
#include "llvm/Analysis/DataStructure.h"
#include "llvm/Analysis/DSGraph.h"
#include "llvm/Module.h"
#include "llvm/Function.h"
#include "llvm/iMemory.h"
#include "llvm/iOther.h"
#include "Support/Statistic.h"
#include "Support/STLExtras.h"
#include "Support/StringExtras.h"
#include <vector>
//----------------------------------------------------------------------------
// Private constants and data
//----------------------------------------------------------------------------
static RegisterAnalysis<IPModRef>
Z("ipmodref", "Interprocedural mod/ref analysis");
//----------------------------------------------------------------------------
// class ModRefInfo
//----------------------------------------------------------------------------
void ModRefInfo::print(std::ostream &O,
const std::string& sprefix) const
{
O << sprefix << "Modified nodes = " << modNodeSet;
O << sprefix << "Referenced nodes = " << refNodeSet;
}
void ModRefInfo::dump() const
{
print(std::cerr);
}
//----------------------------------------------------------------------------
// class FunctionModRefInfo
//----------------------------------------------------------------------------
// This constructor computes a node numbering for the TD graph.
//
FunctionModRefInfo::FunctionModRefInfo(const Function& func,
IPModRef& ipmro,
DSGraph* tdgClone)
: F(func), IPModRefObj(ipmro),
funcTDGraph(tdgClone),
funcModRefInfo(tdgClone->getGraphSize())
{
for (unsigned i=0, N = funcTDGraph->getGraphSize(); i < N; ++i)
NodeIds[funcTDGraph->getNodes()[i]] = i;
}
FunctionModRefInfo::~FunctionModRefInfo()
{
for(std::map<const CallInst*, ModRefInfo*>::iterator
I=callSiteModRefInfo.begin(), E=callSiteModRefInfo.end(); I != E; ++I)
delete(I->second);
// Empty map just to make problems easier to track down
callSiteModRefInfo.clear();
delete funcTDGraph;
}
unsigned FunctionModRefInfo::getNodeId(const Value* value) const {
return getNodeId(funcTDGraph->getNodeForValue(const_cast<Value*>(value))
.getNode());
}
// Compute Mod/Ref bit vectors for the entire function.
// These are simply copies of the Read/Write flags from the nodes of
// the top-down DS graph.
//
void FunctionModRefInfo::computeModRef(const Function &func)
{
// Mark all nodes in the graph that are marked MOD as being mod
// and all those marked REF as being ref.
for (unsigned i = 0, N = funcTDGraph->getGraphSize(); i < N; ++i)
{
if (funcTDGraph->getNodes()[i]->isModified())
funcModRefInfo.setNodeIsMod(i);
if (funcTDGraph->getNodes()[i]->isRead())
funcModRefInfo.setNodeIsRef(i);
}
// Compute the Mod/Ref info for all call sites within the function.
// The call sites are recorded in the TD graph.
const std::vector<DSCallSite>& callSites = funcTDGraph->getFunctionCalls();
for (unsigned i = 0, N = callSites.size(); i < N; ++i)
computeModRef(callSites[i].getCallInst());
}
// ResolveCallSiteModRefInfo - This method performs the following actions:
//
// 1. It clones the top-down graph for the current function
// 2. It clears all of the mod/ref bits in the cloned graph
// 3. It then merges the bottom-up graph(s) for the specified call-site into
// the clone (bringing new mod/ref bits).
// 4. It returns the clone, and a mapping of nodes from the original TDGraph to
// the cloned graph with Mod/Ref info for the callsite.
//
// NOTE: Because this clones a dsgraph and returns it, the caller is responsible
// for deleting the returned graph!
// NOTE: This method may return a null pointer if it is unable to determine the
// requested information (because the call site calls an external
// function or we cannot determine the complete set of functions invoked).
//
DSGraph* FunctionModRefInfo::ResolveCallSiteModRefInfo(CallInst &CI,
hash_map<const DSNode*, DSNodeHandle> &NodeMap)
{
// Step #0: Quick check if we are going to fail anyway: avoid
// all the graph cloning and map copying in steps #1 and #2.
//
if (const Function *F = CI.getCalledFunction())
{
if (F->isExternal())
return 0; // We cannot compute Mod/Ref info for this callsite...
}
else
{
// Eventually, should check here if any callee is external.
// For now we are not handling this case anyway.
std::cerr << "IP Mod/Ref indirect call not implemented yet: "
<< "Being conservative\n";
return 0; // We cannot compute Mod/Ref info for this callsite...
}
// Step #1: Clone the top-down graph...
DSGraph *Result = new DSGraph(*funcTDGraph, NodeMap);
// Step #2: Clear Mod/Ref information...
Result->maskNodeTypes(~(DSNode::Modified | DSNode::Read));
// Step #3: clone the bottom up graphs for the callees into the caller graph
if (Function *F = CI.getCalledFunction())
{
assert(!F->isExternal());
// Build up a DSCallSite for our invocation point here...
// If the call returns a value, make sure to merge the nodes...
DSNodeHandle RetVal;
if (DS::isPointerType(CI.getType()))
RetVal = Result->getNodeForValue(&CI);
// Populate the arguments list...
std::vector<DSNodeHandle> Args;
for (unsigned i = 1, e = CI.getNumOperands(); i != e; ++i)
if (DS::isPointerType(CI.getOperand(i)->getType()))
Args.push_back(Result->getNodeForValue(CI.getOperand(i)));
// Build the call site...
DSCallSite CS(CI, RetVal, F, Args);
// Perform the merging now of the graph for the callee, which will
// come with mod/ref bits set...
Result->mergeInGraph(CS, IPModRefObj.getBUDSGraph(*F),
DSGraph::StripAllocaBit
| DSGraph::DontCloneCallNodes
| DSGraph::DontCloneAuxCallNodes);
}
else
assert(0 && "See error message");
// Remove dead nodes aggressively to match the caller's original graph.
Result->removeDeadNodes(DSGraph::KeepUnreachableGlobals);
// Step #4: Return the clone + the mapping (by ref)
return Result;
}
// Compute Mod/Ref bit vectors for a single call site.
// These are copies of the Read/Write flags from the nodes of
// the graph produced by clearing all flags in teh caller's TD graph
// and then inlining the callee's BU graph into the caller's TD graph.
//
void
FunctionModRefInfo::computeModRef(const CallInst& callInst)
{
// Allocate the mod/ref info for the call site. Bits automatically cleared.
ModRefInfo* callModRefInfo = new ModRefInfo(funcTDGraph->getGraphSize());
callSiteModRefInfo[&callInst] = callModRefInfo;
// Get a copy of the graph for the callee with the callee inlined
hash_map<const DSNode*, DSNodeHandle> NodeMap;
DSGraph* csgp = ResolveCallSiteModRefInfo(const_cast<CallInst&>(callInst),
NodeMap);
if (!csgp)
{ // Callee's side effects are unknown: mark all nodes Mod and Ref.
// Eventually this should only mark nodes visible to the callee, i.e.,
// exclude stack variables not reachable from any outgoing argument
// or any global.
callModRefInfo->getModSet().set();
callModRefInfo->getRefSet().set();
return;
}
// For all nodes in the graph, extract the mod/ref information
const std::vector<DSNode*>& csgNodes = csgp->getNodes();
const std::vector<DSNode*>& origNodes = funcTDGraph->getNodes();
assert(csgNodes.size() == origNodes.size());
for (unsigned i=0, N = origNodes.size(); i < N; ++i)
{
DSNode* csgNode = NodeMap[origNodes[i]].getNode();
assert(csgNode && "Inlined and original graphs do not correspond!");
if (csgNode->isModified())
callModRefInfo->setNodeIsMod(getNodeId(origNodes[i]));
if (csgNode->isRead())
callModRefInfo->setNodeIsRef(getNodeId(origNodes[i]));
}
// Drop nodemap before we delete the graph...
NodeMap.clear();
delete csgp;
}
class DSGraphPrintHelper {
const DSGraph& tdGraph;
std::vector<std::vector<const Value*> > knownValues; // identifiable objects
public:
/*ctor*/ DSGraphPrintHelper(const FunctionModRefInfo& fmrInfo)
: tdGraph(fmrInfo.getFuncGraph())
{
knownValues.resize(tdGraph.getGraphSize());
// For every identifiable value, save Value pointer in knownValues[i]
for (hash_map<Value*, DSNodeHandle>::const_iterator
I = tdGraph.getScalarMap().begin(),
E = tdGraph.getScalarMap().end(); I != E; ++I)
if (isa<GlobalValue>(I->first) ||
isa<Argument>(I->first) ||
isa<LoadInst>(I->first) ||
isa<AllocaInst>(I->first) ||
isa<MallocInst>(I->first))
{
unsigned nodeId = fmrInfo.getNodeId(I->second.getNode());
knownValues[nodeId].push_back(I->first);
}
}
void printValuesInBitVec(std::ostream &O, const BitSetVector& bv) const
{
assert(bv.size() == knownValues.size());
if (bv.none())
{ // No bits are set: just say so and return
O << "\tNONE.\n";
return;
}
if (bv.all())
{ // All bits are set: just say so and return
O << "\tALL GRAPH NODES.\n";
return;
}
for (unsigned i=0, N=bv.size(); i < N; ++i)
if (bv.test(i))
{
O << "\tNode# " << i << " : ";
if (! knownValues[i].empty())
for (unsigned j=0, NV=knownValues[i].size(); j < NV; j++)
{
const Value* V = knownValues[i][j];
if (isa<GlobalValue>(V)) O << "(Global) ";
else if (isa<Argument>(V)) O << "(Target of FormalParm) ";
else if (isa<LoadInst>(V)) O << "(Target of LoadInst ) ";
else if (isa<AllocaInst>(V)) O << "(Target of AllocaInst) ";
else if (isa<MallocInst>(V)) O << "(Target of MallocInst) ";
if (V->hasName()) O << V->getName();
else if (isa<Instruction>(V)) O << *V;
else O << "(Value*) 0x" << (void*) V;
O << std::string((j < NV-1)? "; " : "\n");
}
else
tdGraph.getNodes()[i]->print(O, /*graph*/ NULL);
}
}
};
// Print the results of the pass.
// Currently this just prints bit-vectors and is not very readable.
//
void FunctionModRefInfo::print(std::ostream &O) const
{
DSGraphPrintHelper DPH(*this);
O << "========== Mod/ref information for function "
<< F.getName() << "========== \n\n";
// First: Print Globals and Locals modified anywhere in the function.
//
O << " -----Mod/Ref in the body of function " << F.getName()<< ":\n";
O << " --Objects modified in the function body:\n";
DPH.printValuesInBitVec(O, funcModRefInfo.getModSet());
O << " --Objects referenced in the function body:\n";
DPH.printValuesInBitVec(O, funcModRefInfo.getRefSet());
O << " --Mod and Ref vectors for the nodes listed above:\n";
funcModRefInfo.print(O, "\t");
O << "\n";
// Second: Print Globals and Locals modified at each call site in function
//
for (std::map<const CallInst*, ModRefInfo*>::const_iterator
CI = callSiteModRefInfo.begin(), CE = callSiteModRefInfo.end();
CI != CE; ++CI)
{
O << " ----Mod/Ref information for call site\n" << CI->first;
O << " --Objects modified at call site:\n";
DPH.printValuesInBitVec(O, CI->second->getModSet());
O << " --Objects referenced at call site:\n";
DPH.printValuesInBitVec(O, CI->second->getRefSet());
O << " --Mod and Ref vectors for the nodes listed above:\n";
CI->second->print(O, "\t");
O << "\n";
}
O << "\n";
}
void FunctionModRefInfo::dump() const
{
print(std::cerr);
}
//----------------------------------------------------------------------------
// class IPModRef: An interprocedural pass that computes IP Mod/Ref info.
//----------------------------------------------------------------------------
// Free the FunctionModRefInfo objects cached in funcToModRefInfoMap.
//
void IPModRef::releaseMemory()
{
for(std::map<const Function*, FunctionModRefInfo*>::iterator
I=funcToModRefInfoMap.begin(), E=funcToModRefInfoMap.end(); I != E; ++I)
delete(I->second);
// Clear map so memory is not re-released if we are called again
funcToModRefInfoMap.clear();
}
// Run the "interprocedural" pass on each function. This needs to do
// NO real interprocedural work because all that has been done the
// data structure analysis.
//
bool IPModRef::run(Module &theModule)
{
M = &theModule;
for (Module::const_iterator FI = M->begin(), FE = M->end(); FI != FE; ++FI)
if (! FI->isExternal())
getFuncInfo(*FI, /*computeIfMissing*/ true);
return true;
}
FunctionModRefInfo& IPModRef::getFuncInfo(const Function& func,
bool computeIfMissing)
{
FunctionModRefInfo*& funcInfo = funcToModRefInfoMap[&func];
assert (funcInfo != NULL || computeIfMissing);
if (funcInfo == NULL)
{ // Create a new FunctionModRefInfo object.
// Clone the top-down graph and remove any dead nodes first, because
// otherwise original and merged graphs will not match.
// The memory for this graph clone will be freed by FunctionModRefInfo.
DSGraph* funcTDGraph =
new DSGraph(getAnalysis<TDDataStructures>().getDSGraph(func));
funcTDGraph->removeDeadNodes(DSGraph::KeepUnreachableGlobals);
funcInfo = new FunctionModRefInfo(func, *this, funcTDGraph); //auto-insert
funcInfo->computeModRef(func); // computes the mod/ref info
}
return *funcInfo;
}
/// getBUDSGraph - This method returns the BU data structure graph for F through
/// the use of the BUDataStructures object.
///
const DSGraph &IPModRef::getBUDSGraph(const Function &F) {
return getAnalysis<BUDataStructures>().getDSGraph(F);
}
// getAnalysisUsage - This pass requires top-down data structure graphs.
// It modifies nothing.
//
void IPModRef::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<LocalDataStructures>();
AU.addRequired<BUDataStructures>();
AU.addRequired<TDDataStructures>();
}
void IPModRef::print(std::ostream &O) const
{
O << "\nRESULTS OF INTERPROCEDURAL MOD/REF ANALYSIS:\n\n";
for (std::map<const Function*, FunctionModRefInfo*>::const_iterator
mapI = funcToModRefInfoMap.begin(), mapE = funcToModRefInfoMap.end();
mapI != mapE; ++mapI)
mapI->second->print(O);
O << "\n";
}
void IPModRef::dump() const
{
print(std::cerr);
}