mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-20 11:29:24 +00:00
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21416 91177308-0d34-0410-b5e6-96231b3b80d8
268 lines
9.6 KiB
C++
268 lines
9.6 KiB
C++
//===- 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
|
|
// graphs for all of the functions, then merging them together into a single big
|
|
// graph without cloning.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Analysis/DataStructure/DataStructure.h"
|
|
#include "llvm/Analysis/DataStructure/DSGraph.h"
|
|
#include "llvm/Analysis/AliasAnalysis.h"
|
|
#include "llvm/Analysis/Passes.h"
|
|
#include "llvm/Module.h"
|
|
#include "llvm/Support/Debug.h"
|
|
using namespace llvm;
|
|
|
|
namespace {
|
|
class Steens : public ModulePass, public AliasAnalysis {
|
|
DSGraph *ResultGraph;
|
|
|
|
EquivalenceClasses<GlobalValue*> GlobalECs; // Always empty
|
|
public:
|
|
Steens() : ResultGraph(0) {}
|
|
~Steens() {
|
|
releaseMyMemory();
|
|
assert(ResultGraph == 0 && "releaseMemory not called?");
|
|
}
|
|
|
|
//------------------------------------------------
|
|
// Implement the Pass API
|
|
//
|
|
|
|
// run - Build up the result graph, representing the pointer graph for the
|
|
// program.
|
|
//
|
|
bool runOnModule(Module &M);
|
|
|
|
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
|
|
}
|
|
|
|
// print - Implement the Pass::print method...
|
|
void print(std::ostream &O, const Module *M) const {
|
|
assert(ResultGraph && "Result graph has not yet been computed!");
|
|
ResultGraph->writeGraphToFile(O, "steensgaards");
|
|
}
|
|
|
|
//------------------------------------------------
|
|
// Implement the AliasAnalysis API
|
|
//
|
|
|
|
AliasResult alias(const Value *V1, unsigned V1Size,
|
|
const Value *V2, unsigned V2Size);
|
|
|
|
ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
|
|
|
|
private:
|
|
void ResolveFunctionCall(Function *F, const DSCallSite &Call,
|
|
DSNodeHandle &RetVal);
|
|
};
|
|
|
|
// Register the pass...
|
|
RegisterOpt<Steens> X("steens-aa",
|
|
"Steensgaard's alias analysis (DSGraph based)");
|
|
|
|
// Register as an implementation of AliasAnalysis
|
|
RegisterAnalysisGroup<AliasAnalysis, Steens> Y;
|
|
}
|
|
|
|
ModulePass *llvm::createSteensgaardPass() { return new Steens(); }
|
|
|
|
/// 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 DSCallSite &Call,
|
|
DSNodeHandle &RetVal) {
|
|
assert(ResultGraph != 0 && "Result graph not allocated!");
|
|
DSGraph::ScalarMapTy &ValMap = ResultGraph->getScalarMap();
|
|
|
|
// 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 PtrArgIdx = 0;
|
|
for (Function::arg_iterator AI = F->arg_begin(), AE = F->arg_end();
|
|
AI != AE && PtrArgIdx < Call.getNumPtrArgs(); ++AI) {
|
|
DSGraph::ScalarMapTy::iterator I = ValMap.find(AI);
|
|
if (I != ValMap.end()) // If its a pointer argument...
|
|
I->second.mergeWith(Call.getPtrArg(PtrArgIdx++));
|
|
}
|
|
}
|
|
|
|
|
|
/// run - Build up the result graph, representing the pointer graph for the
|
|
/// program.
|
|
///
|
|
bool Steens::runOnModule(Module &M) {
|
|
InitializeAliasAnalysis(this);
|
|
assert(ResultGraph == 0 && "Result graph already allocated!");
|
|
LocalDataStructures &LDS = getAnalysis<LocalDataStructures>();
|
|
|
|
// Create a new, empty, graph...
|
|
ResultGraph = new DSGraph(GlobalECs, getTargetData());
|
|
ResultGraph->spliceFrom(LDS.getGlobalsGraph());
|
|
|
|
// Loop over the rest of the module, merging graphs for non-external functions
|
|
// into this graph.
|
|
//
|
|
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
|
|
if (!I->isExternal())
|
|
ResultGraph->spliceFrom(LDS.getDSGraph(*I));
|
|
|
|
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::list<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 (std::list<DSCallSite>::iterator CI = Calls.begin(), E = Calls.end();
|
|
CI != E;) {
|
|
DSCallSite &CurCall = *CI++;
|
|
|
|
// Loop over the called functions, eliminating as many as possible...
|
|
std::vector<Function*> CallTargets;
|
|
if (CurCall.isDirectCall())
|
|
CallTargets.push_back(CurCall.getCalleeFunc());
|
|
else
|
|
CurCall.getCalleeNode()->addFullFunctionList(CallTargets);
|
|
|
|
for (unsigned c = 0; c != CallTargets.size(); ) {
|
|
// If we can eliminate this function call, do so!
|
|
Function *F = CallTargets[c];
|
|
if (!F->isExternal()) {
|
|
ResolveFunctionCall(F, CurCall, ResultGraph->getReturnNodes()[F]);
|
|
CallTargets[c] = CallTargets.back();
|
|
CallTargets.pop_back();
|
|
} else
|
|
++c; // Cannot eliminate this call, skip over it...
|
|
}
|
|
|
|
if (CallTargets.empty()) { // Eliminated all calls?
|
|
std::list<DSCallSite>::iterator I = CI;
|
|
Calls.erase(--I); // Remove entry
|
|
}
|
|
}
|
|
|
|
// Remove our knowledge of what the return values of the functions are, except
|
|
// for functions that are externally visible from this module (e.g. main). We
|
|
// keep these functions so that their arguments are marked incomplete.
|
|
for (DSGraph::ReturnNodesTy::iterator I =
|
|
ResultGraph->getReturnNodes().begin(),
|
|
E = ResultGraph->getReturnNodes().end(); I != E; )
|
|
if (I->first->hasInternalLinkage())
|
|
ResultGraph->getReturnNodes().erase(I++);
|
|
else
|
|
++I;
|
|
|
|
// Update the "incomplete" markers on the nodes, ignoring unknownness due to
|
|
// incoming arguments...
|
|
ResultGraph->maskIncompleteMarkers();
|
|
ResultGraph->markIncompleteNodes(DSGraph::IgnoreGlobals |
|
|
DSGraph::MarkFormalArgs);
|
|
|
|
// Remove any nodes that are dead after all of the merging we have done...
|
|
// FIXME: We should be able to disable the globals graph for steens!
|
|
//ResultGraph->removeDeadNodes(DSGraph::KeepUnreachableGlobals);
|
|
|
|
DEBUG(print(std::cerr, &M));
|
|
return false;
|
|
}
|
|
|
|
AliasAnalysis::AliasResult Steens::alias(const Value *V1, unsigned V1Size,
|
|
const Value *V2, unsigned V2Size) {
|
|
assert(ResultGraph && "Result graph has not been computed yet!");
|
|
|
|
DSGraph::ScalarMapTy &GSM = ResultGraph->getScalarMap();
|
|
|
|
DSGraph::ScalarMapTy::iterator I = GSM.find(const_cast<Value*>(V1));
|
|
DSGraph::ScalarMapTy::iterator J = GSM.find(const_cast<Value*>(V2));
|
|
if (I != GSM.end() && !I->second.isNull() &&
|
|
J != GSM.end() && !J->second.isNull()) {
|
|
DSNodeHandle &V1H = I->second;
|
|
DSNodeHandle &V2H = J->second;
|
|
|
|
// If at least one of the nodes is complete, we can say something about
|
|
// this. If one is complete and the other isn't, then they are obviously
|
|
// different nodes. If they are both complete, we can't say anything
|
|
// useful.
|
|
if (I->second.getNode()->isComplete() ||
|
|
J->second.getNode()->isComplete()) {
|
|
// If the two pointers point to different data structure graph nodes, they
|
|
// cannot alias!
|
|
if (V1H.getNode() != V2H.getNode())
|
|
return NoAlias;
|
|
|
|
// See if they point to different offsets... if so, we may be able to
|
|
// determine that they do not alias...
|
|
unsigned O1 = I->second.getOffset(), O2 = J->second.getOffset();
|
|
if (O1 != O2) {
|
|
if (O2 < O1) { // Ensure that O1 <= O2
|
|
std::swap(V1, V2);
|
|
std::swap(O1, O2);
|
|
std::swap(V1Size, V2Size);
|
|
}
|
|
|
|
if (O1+V1Size <= O2)
|
|
return NoAlias;
|
|
}
|
|
}
|
|
}
|
|
|
|
// If we cannot determine alias properties based on our graph, fall back on
|
|
// some other AA implementation.
|
|
//
|
|
return AliasAnalysis::alias(V1, V1Size, V2, V2Size);
|
|
}
|
|
|
|
AliasAnalysis::ModRefResult
|
|
Steens::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
|
|
AliasAnalysis::ModRefResult Result = ModRef;
|
|
|
|
// Find the node in question.
|
|
DSGraph::ScalarMapTy &GSM = ResultGraph->getScalarMap();
|
|
DSGraph::ScalarMapTy::iterator I = GSM.find(P);
|
|
|
|
if (I != GSM.end() && !I->second.isNull()) {
|
|
DSNode *N = I->second.getNode();
|
|
if (N->isComplete()) {
|
|
// If this is a direct call to an external function, and if the pointer
|
|
// points to a complete node, the external function cannot modify or read
|
|
// the value (we know it's not passed out of the program!).
|
|
if (Function *F = CS.getCalledFunction())
|
|
if (F->isExternal())
|
|
return NoModRef;
|
|
|
|
// Otherwise, if the node is complete, but it is only M or R, return this.
|
|
// This can be useful for globals that should be marked const but are not.
|
|
if (!N->isModified())
|
|
Result = (ModRefResult)(Result & ~Mod);
|
|
if (!N->isRead())
|
|
Result = (ModRefResult)(Result & ~Ref);
|
|
}
|
|
}
|
|
|
|
return (ModRefResult)(Result & AliasAnalysis::getModRefInfo(CS, P, Size));
|
|
}
|