//===- Steensgaard.cpp - Context Insensitive Alias Analysis ---------------===//
+//
+// 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 uses the data structure graphs to implement a simple context
// insensitive alias analysis. It does this by computing the local analysis
#include "llvm/Analysis/DSGraph.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Module.h"
-#include "Support/Statistic.h"
+#include "Support/Debug.h"
+using namespace llvm;
namespace {
class Steens : public Pass, public AliasAnalysis {
DSGraph *ResultGraph;
+ DSGraph *GlobalsGraph; // FIXME: Eliminate globals graph stuff from DNE
public:
- Steens() : ResultGraph(0) {}
- ~Steens() { assert(ResultGraph == 0 && "releaseMemory not called?"); }
+ Steens() : ResultGraph(0), GlobalsGraph(0) {}
+ ~Steens() {
+ releaseMyMemory();
+ assert(ResultGraph == 0 && "releaseMemory not called?");
+ }
//------------------------------------------------
// Implement the Pass API
//
bool run(Module &M);
- virtual void releaseMemory() { delete ResultGraph; ResultGraph = 0; }
+ virtual void releaseMyMemory() { delete ResultGraph; ResultGraph = 0; }
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AliasAnalysis::getAnalysisUsage(AU);
AU.setPreservesAll(); // Does not transform code...
AU.addRequired<LocalDataStructures>(); // Uses local dsgraph
AU.addRequired<AliasAnalysis>(); // Chains to another AA impl...
//
// alias - This is the only method here that does anything interesting...
- Result alias(const Value *V1, const Value *V2) const;
-
- /// canCallModify - We are not interprocedural, so we do nothing exciting.
- ///
- Result canCallModify(const CallInst &CI, const Value *Ptr) const {
- return MayAlias;
+ AliasResult alias(const Value *V1, unsigned V1Size,
+ const Value *V2, unsigned V2Size);
+
+ bool pointsToConstantMemory(const Value *P) {
+ return getAnalysis<AliasAnalysis>().pointsToConstantMemory(P);
}
- /// canInvokeModify - We are not interprocedural, so we do nothing exciting.
- ///
- Result canInvokeModify(const InvokeInst &I, const Value *Ptr) const {
- return MayAlias; // We are not interprocedural
- }
-
private:
- void ResolveFunctionCall(Function *F, const std::vector<DSNodeHandle> &Call,
+ void ResolveFunctionCall(Function *F, const DSCallSite &Call,
DSNodeHandle &RetVal);
};
// Register the pass...
RegisterOpt<Steens> X("steens-aa",
- "Steensgaard's FlowInsensitive/ConIns alias analysis");
+ "Steensgaard's alias analysis (DSGraph based)");
// Register as an implementation of AliasAnalysis
RegisterAnalysisGroup<AliasAnalysis, Steens> Y;
}
-
/// ResolveFunctionCall - Resolve the actual arguments of a call to function F
/// with the specified call site descriptor. This function links the arguments
/// and the return value for the call site context-insensitively.
///
-void Steens::ResolveFunctionCall(Function *F,
- const std::vector<DSNodeHandle> &Call,
+void Steens::ResolveFunctionCall(Function *F, const DSCallSite &Call,
DSNodeHandle &RetVal) {
assert(ResultGraph != 0 && "Result graph not allocated!");
- std::map<Value*, DSNodeHandle> &ValMap = ResultGraph->getValueMap();
+ DSGraph::ScalarMapTy &ValMap = ResultGraph->getScalarMap();
- // Handle the return value of the function... which is Call[0]
- if (Call[0].getNode() && RetVal.getNode())
- RetVal.mergeWith(Call[0]);
+ // Handle the return value of the function...
+ if (Call.getRetVal().getNode() && RetVal.getNode())
+ RetVal.mergeWith(Call.getRetVal());
// Loop over all pointer arguments, resolving them to their provided pointers
- unsigned ArgIdx = 2; // Skip retval and function to call...
- for (Function::aiterator AI = F->abegin(), AE = F->aend(); AI != AE; ++AI) {
- std::map<Value*, DSNodeHandle>::iterator I = ValMap.find(AI);
+ unsigned PtrArgIdx = 0;
+ for (Function::aiterator AI = F->abegin(), AE = F->aend();
+ AI != AE && PtrArgIdx < Call.getNumPtrArgs(); ++AI) {
+ DSGraph::ScalarMapTy::iterator I = ValMap.find(AI);
if (I != ValMap.end()) // If its a pointer argument...
- I->second.addEdgeTo(Call[ArgIdx++]);
+ I->second.mergeWith(Call.getPtrArg(PtrArgIdx++));
}
-
- assert(ArgIdx == Call.size() && "Argument resolution mismatch!");
}
/// program.
///
bool Steens::run(Module &M) {
+ InitializeAliasAnalysis(this);
assert(ResultGraph == 0 && "Result graph already allocated!");
LocalDataStructures &LDS = getAnalysis<LocalDataStructures>();
// Create a new, empty, graph...
- ResultGraph = new DSGraph();
+ ResultGraph = new DSGraph(getTargetData());
+ GlobalsGraph = new DSGraph(getTargetData());
+ ResultGraph->setGlobalsGraph(GlobalsGraph);
+ ResultGraph->setPrintAuxCalls();
// RetValMap - Keep track of the return values for all functions that return
// valid pointers.
//
- std::map<Function*, DSNodeHandle> RetValMap;
+ DSGraph::ReturnNodesTy RetValMap;
// Loop over the rest of the module, merging graphs for non-external functions
// into this graph.
//
+ unsigned Count = 0;
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
if (!I->isExternal()) {
- std::map<Value*, DSNodeHandle> ValMap;
+ DSGraph::ScalarMapTy ValMap;
{ // Scope to free NodeMap memory ASAP
- std::map<const DSNode*, DSNode*> NodeMap;
+ DSGraph::NodeMapTy NodeMap;
const DSGraph &FDSG = LDS.getDSGraph(*I);
- DSNodeHandle RetNode = ResultGraph->cloneInto(FDSG, ValMap, NodeMap);
-
- // Keep track of the return node of the function's graph if it returns a
- // value...
- //
- if (RetNode.getNode())
- RetValMap[I] = RetNode;
+ ResultGraph->cloneInto(FDSG, ValMap, RetValMap, NodeMap,
+ DSGraph::UpdateInlinedGlobals);
}
- // Incorporate the inlined Function's ValueMap into the global ValueMap...
- std::map<Value*, DSNodeHandle> &GVM = ResultGraph->getValueMap();
-
- while (!ValMap.empty()) { // Loop over value map, moving entries over...
- const std::pair<Value*, DSNodeHandle> &DSN = *ValMap.begin();
- std::map<Value*, DSNodeHandle>::iterator I = GVM.find(DSN.first);
- if (I == GVM.end())
- GVM[DSN.first] = DSN.second;
- else
- I->second.mergeWith(DSN.second);
- ValMap.erase(ValMap.begin());
- }
+ // Incorporate the inlined Function's ScalarMap into the global
+ // ScalarMap...
+ DSGraph::ScalarMapTy &GVM = ResultGraph->getScalarMap();
+ for (DSGraph::ScalarMapTy::iterator I = ValMap.begin(),
+ E = ValMap.end(); I != E; ++I)
+ GVM[I->first].mergeWith(I->second);
+
+ if ((++Count & 1) == 0) // Prune nodes out every other time...
+ ResultGraph->removeTriviallyDeadNodes();
}
// FIXME: Must recalculate and use the Incomplete markers!!
// Now that we have all of the graphs inlined, we can go about eliminating
// call nodes...
//
- std::vector<std::vector<DSNodeHandle> > &Calls =
- ResultGraph->getFunctionCalls();
+ std::vector<DSCallSite> &Calls =
+ ResultGraph->getAuxFunctionCalls();
+ assert(Calls.empty() && "Aux call list is already in use??");
+
+ // Start with a copy of the original call sites...
+ Calls = ResultGraph->getFunctionCalls();
+
for (unsigned i = 0; i != Calls.size(); ) {
- std::vector<DSNodeHandle> &CurCall = Calls[i];
+ DSCallSite &CurCall = Calls[i];
// Loop over the called functions, eliminating as many as possible...
- std::vector<GlobalValue*> CallTargets = CurCall[1].getNode()->getGlobals();
+ std::vector<GlobalValue*> CallTargets;
+ if (CurCall.isDirectCall())
+ CallTargets.push_back(CurCall.getCalleeFunc());
+ else
+ CallTargets = CurCall.getCalleeNode()->getGlobals();
+
for (unsigned c = 0; c != CallTargets.size(); ) {
// If we can eliminate this function call, do so!
bool Eliminated = false;
ResolveFunctionCall(F, CurCall, RetValMap[F]);
Eliminated = true;
}
- if (Eliminated)
- CallTargets.erase(CallTargets.begin()+c);
- else
+ if (Eliminated) {
+ CallTargets[c] = CallTargets.back();
+ CallTargets.pop_back();
+ } else
++c; // Cannot eliminate this call, skip over it...
}
- if (CallTargets.empty()) // Eliminated all calls?
- Calls.erase(Calls.begin()+i); // Remove from call list...
- else
+ if (CallTargets.empty()) { // Eliminated all calls?
+ CurCall = Calls.back(); // Remove entry
+ Calls.pop_back();
+ } else
++i; // Skip this call site...
}
+ RetValMap.clear();
+
// Update the "incomplete" markers on the nodes, ignoring unknownness due to
// incoming arguments...
ResultGraph->maskIncompleteMarkers();
- ResultGraph->markIncompleteNodes(false);
+ ResultGraph->markIncompleteNodes(DSGraph::IgnoreFormalArgs);
// Remove any nodes that are dead after all of the merging we have done...
- ResultGraph->removeTriviallyDeadNodes();
+ // FIXME: We should be able to disable the globals graph for steens!
+ ResultGraph->removeDeadNodes(DSGraph::KeepUnreachableGlobals);
DEBUG(print(std::cerr, &M));
return false;
}
// alias - This is the only method here that does anything interesting...
-AliasAnalysis::Result Steens::alias(const Value *V1, const Value *V2) const {
- assert(ResultGraph && "Result grcaph has not yet been computed!");
+AliasAnalysis::AliasResult Steens::alias(const Value *V1, unsigned V1Size,
+ const Value *V2, unsigned V2Size) {
+ // FIXME: HANDLE Size argument!
+ assert(ResultGraph && "Result graph has not been computed yet!");
- std::map<Value*, DSNodeHandle> &GVM = ResultGraph->getValueMap();
+ DSGraph::ScalarMapTy &GSM = ResultGraph->getScalarMap();
- std::map<Value*, DSNodeHandle>::iterator I = GVM.find(const_cast<Value*>(V1));
- if (I != GVM.end() && I->second.getNode()) {
+ DSGraph::ScalarMapTy::iterator I = GSM.find(const_cast<Value*>(V1));
+ if (I != GSM.end() && I->second.getNode()) {
DSNodeHandle &V1H = I->second;
- std::map<Value*, DSNodeHandle>::iterator J=GVM.find(const_cast<Value*>(V2));
- if (J != GVM.end() && J->second.getNode()) {
+ DSGraph::ScalarMapTy::iterator J=GSM.find(const_cast<Value*>(V2));
+ if (J != GSM.end() && J->second.getNode()) {
DSNodeHandle &V2H = J->second;
// If the two pointers point to different data structure graph nodes, they
// cannot alias!
- if (V1H.getNode() != V2H.getNode())
+ if (V1H.getNode() != V2H.getNode()) // FIXME: Handle incompleteness!
return NoAlias;
// FIXME: If the two pointers point to the same node, and the offsets are
// If we cannot determine alias properties based on our graph, fall back on
// some other AA implementation.
//
- return getAnalysis<AliasAnalysis>().alias(V1, V2);
+ return getAnalysis<AliasAnalysis>().alias(V1, V1Size, V2, V2Size);
}
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