/// Model the effect of an instruction on the set of available values.
static void TransferInstruction(const Instruction &I, bool &Cleared,
DenseSet<const Value *> &Available) {
if (isStatepoint(I)) {
Cleared = true;
Available.clear();
} else if (containsGCPtrType(I.getType()))
Available.insert(&I);
}
void AliasAnalysisChecker::collectDynamicAliases(
DenseSet<ValuePair> &DynamicAliases) {
DynamicAliases.clear();
if (InputDynamicAliases == "") {
DynamicAliasAnalysis &DAA = getAnalysis<DynamicAliasAnalysis>();
DynamicAliases.insert(DAA.getAllAliases().begin(),
DAA.getAllAliases().end());
} else {
IDAssigner &IDA = getAnalysis<IDAssigner>();
ifstream InputFile(InputDynamicAliases.c_str());
unsigned VID1, VID2;
while (InputFile >> VID1 >> VID2) {
Value *V1 = IDA.getValue(VID1), *V2 = IDA.getValue(VID2);
DynamicAliases.insert(make_pair(V1, V2));
}
}
}
/// Removes redundant check_unowned calls if they check the same reference and
/// there is no instruction in between which could decrement the reference count.
static void performRedundantCheckUnownedRemoval(BasicBlock &BB) {
DenseSet<Value *> checkedValues;
for (BasicBlock::iterator BBI = BB.begin(), E = BB.end(); BBI != E; ) {
// Preincrement the iterator to avoid invalidation and out trouble.
Instruction &I = *BBI++;
switch (classifyInstruction(I)) {
case RT_NoMemoryAccessed:
case RT_AllocObject:
case RT_FixLifetime:
case RT_Retain:
case RT_UnknownRetain:
case RT_BridgeRetain:
case RT_RetainUnowned:
case RT_ObjCRetain:
// All this cannot decrement reference counts.
continue;
case RT_CheckUnowned: {
Value *Arg = cast<CallInst>(&I)->getArgOperand(0);
if (checkedValues.count(Arg) != 0) {
// We checked this reference already -> delete the second check.
I.eraseFromParent();
} else {
// Record the check.
checkedValues.insert(Arg);
}
continue;
}
case RT_Unknown:
// Loads cannot affect the retain.
if (isa<LoadInst>(I) || isa<StoreInst>(I) || isa<MemIntrinsic>(I))
continue;
break;
default:
break;
}
// We found some potential reference decrementing instruction. Bail out.
checkedValues.clear();
}
}
// run - Calculate the top down data structure graphs for each function in the
// program.
//
bool TDDataStructures::runOnModule(Module &M) {
init(useEQBU ? &getAnalysis<EquivBUDataStructures>()
: &getAnalysis<BUDataStructures>(),
true, true, true, false);
// Figure out which functions must not mark their arguments complete because
// they are accessible outside this compilation unit. Currently, these
// arguments are functions which are reachable by incomplete or external
// nodes in the globals graph.
const DSScalarMap &GGSM = GlobalsGraph->getScalarMap();
DenseSet<DSNode*> Visited;
for (DSScalarMap::global_iterator I=GGSM.global_begin(), E=GGSM.global_end();
I != E; ++I) {
DSNode *N = GGSM.find(*I)->second.getNode();
if (N->isIncompleteNode() || N->isExternalNode())
markReachableFunctionsExternallyAccessible(N, Visited);
}
// Loop over unresolved call nodes. Any functions passed into (but not
// returned!) from unresolvable call nodes may be invoked outside of the
// current module.
for (DSGraph::afc_iterator I = GlobalsGraph->afc_begin(),
E = GlobalsGraph->afc_end(); I != E; ++I)
for (unsigned arg = 0, e = I->getNumPtrArgs(); arg != e; ++arg)
markReachableFunctionsExternallyAccessible(I->getPtrArg(arg).getNode(),
Visited);
Visited.clear();
// Clear Aux of Globals Graph to be refilled in later by post-TD unresolved
// functions
GlobalsGraph->getAuxFunctionCalls().clear();
// Functions without internal linkage are definitely externally callable!
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
if (!I->isDeclaration() && !I->hasInternalLinkage() && !I->hasPrivateLinkage())
ExternallyCallable.insert(I);
// Debug code to print the functions that are externally callable
#if 0
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
if (ExternallyCallable.count(I)) {
errs() << "ExternallyCallable: " << I->getNameStr() << "\n";
}
#endif
// We want to traverse the call graph in reverse post-order. To do this, we
// calculate a post-order traversal, then reverse it.
DenseSet<DSGraph*> VisitedGraph;
std::vector<DSGraph*> PostOrder;
{TIME_REGION(XXX, "td:Compute postorder");
// Calculate top-down from main...
if (Function *F = M.getFunction("main"))
ComputePostOrder(*F, VisitedGraph, PostOrder);
// Next calculate the graphs for each unreachable function...
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
if (!I->isDeclaration())
ComputePostOrder(*I, VisitedGraph, PostOrder);
VisitedGraph.clear(); // Release memory!
}
{TIME_REGION(XXX, "td:Inline stuff");
// Visit each of the graphs in reverse post-order now!
while (!PostOrder.empty()) {
InlineCallersIntoGraph(PostOrder.back());
PostOrder.pop_back();
}
}
// Free the IndCallMap.
while (!IndCallMap.empty()) {
delete IndCallMap.begin()->second;
IndCallMap.erase(IndCallMap.begin());
}
formGlobalECs();
ExternallyCallable.clear();
GlobalsGraph->removeTriviallyDeadNodes();
GlobalsGraph->computeExternalFlags(DSGraph::DontMarkFormalsExternal);
GlobalsGraph->computeIntPtrFlags();
// Make sure each graph has updated external information about globals
// in the globals graph.
VisitedGraph.clear();
for (Module::iterator F = M.begin(); F != M.end(); ++F) {
if (!(F->isDeclaration())){
DSGraph *Graph = getOrCreateGraph(F);
if (!VisitedGraph.insert(Graph).second) continue;
cloneGlobalsInto(Graph, DSGraph::DontCloneCallNodes |
DSGraph::DontCloneAuxCallNodes);
Graph->computeExternalFlags(DSGraph::DontMarkFormalsExternal);
Graph->computeIntPtrFlags();
// Clean up uninteresting nodes
Graph->removeDeadNodes(0);
}
}
// CBU contains the correct call graph.
// Restore it, so that subsequent passes and clients can get it.
restoreCorrectCallGraph();
/// Added by Zhiyuan: print out the DSGraph.
if (llvm::DebugFlag) {
print(errs(), &M);
}
return false;
}
/// canonicalizeInputFunction - Functions like swift_retain return an
/// argument as a low-level performance optimization. This makes it difficult
/// to reason about pointer equality though, so undo it as an initial
/// canonicalization step. After this step, all swift_retain's have been
/// replaced with swift_retain.
///
/// This also does some trivial peep-hole optimizations as we go.
static bool canonicalizeInputFunction(Function &F, ARCEntryPointBuilder &B,
SwiftRCIdentity *RC) {
bool Changed = false;
DenseSet<Value *> NativeRefs;
DenseMap<Value *, TinyPtrVector<Instruction *>> UnknownRetains;
DenseMap<Value *, TinyPtrVector<Instruction *>> UnknownReleases;
for (auto &BB : F) {
UnknownRetains.clear();
UnknownReleases.clear();
NativeRefs.clear();
for (auto I = BB.begin(); I != BB.end(); ) {
Instruction &Inst = *I++;
switch (classifyInstruction(Inst)) {
// These instructions should not reach here based on the pass ordering.
// i.e. LLVMARCOpt -> LLVMContractOpt.
case RT_RetainN:
case RT_UnknownRetainN:
case RT_BridgeRetainN:
case RT_ReleaseN:
case RT_UnknownReleaseN:
case RT_BridgeReleaseN:
llvm_unreachable("These are only created by LLVMARCContract !");
case RT_Unknown:
case RT_BridgeRelease:
case RT_AllocObject:
case RT_FixLifetime:
case RT_NoMemoryAccessed:
case RT_RetainUnowned:
case RT_CheckUnowned:
break;
case RT_Retain: {
CallInst &CI = cast<CallInst>(Inst);
Value *ArgVal = RC->getSwiftRCIdentityRoot(CI.getArgOperand(0));
// retain(null) is a no-op.
if (isa<ConstantPointerNull>(ArgVal)) {
CI.eraseFromParent();
Changed = true;
++NumNoopDeleted;
continue;
}
// Rewrite unknown retains into swift_retains.
NativeRefs.insert(ArgVal);
for (auto &X : UnknownRetains[ArgVal]) {
B.setInsertPoint(X);
B.createRetain(ArgVal, cast<CallInst>(X));
X->eraseFromParent();
++NumUnknownRetainReleaseSRed;
Changed = true;
}
UnknownRetains[ArgVal].clear();
break;
}
case RT_UnknownRetain: {
CallInst &CI = cast<CallInst>(Inst);
Value *ArgVal = RC->getSwiftRCIdentityRoot(CI.getArgOperand(0));
// unknownRetain(null) is a no-op.
if (isa<ConstantPointerNull>(ArgVal)) {
CI.eraseFromParent();
Changed = true;
++NumNoopDeleted;
continue;
}
// Have not encountered a strong retain/release. keep it in the
// unknown retain/release list for now. It might get replaced
// later.
if (NativeRefs.find(ArgVal) == NativeRefs.end()) {
UnknownRetains[ArgVal].push_back(&CI);
} else {
B.setInsertPoint(&CI);
B.createRetain(ArgVal, &CI);
CI.eraseFromParent();
++NumUnknownRetainReleaseSRed;
Changed = true;
}
break;
}
case RT_Release: {
CallInst &CI = cast<CallInst>(Inst);
Value *ArgVal = RC->getSwiftRCIdentityRoot(CI.getArgOperand(0));
// release(null) is a no-op.
if (isa<ConstantPointerNull>(ArgVal)) {
CI.eraseFromParent();
Changed = true;
++NumNoopDeleted;
continue;
}
// Rewrite unknown releases into swift_releases.
NativeRefs.insert(ArgVal);
for (auto &X : UnknownReleases[ArgVal]) {
B.setInsertPoint(X);
B.createRelease(ArgVal, cast<CallInst>(X));
X->eraseFromParent();
++NumUnknownRetainReleaseSRed;
Changed = true;
}
UnknownReleases[ArgVal].clear();
break;
}
case RT_UnknownRelease: {
CallInst &CI = cast<CallInst>(Inst);
Value *ArgVal = RC->getSwiftRCIdentityRoot(CI.getArgOperand(0));
// unknownRelease(null) is a no-op.
if (isa<ConstantPointerNull>(ArgVal)) {
CI.eraseFromParent();
Changed = true;
++NumNoopDeleted;
continue;
}
// Have not encountered a strong retain/release. keep it in the
// unknown retain/release list for now. It might get replaced
// later.
if (NativeRefs.find(ArgVal) == NativeRefs.end()) {
UnknownReleases[ArgVal].push_back(&CI);
} else {
B.setInsertPoint(&CI);
B.createRelease(ArgVal, &CI);
CI.eraseFromParent();
++NumUnknownRetainReleaseSRed;
Changed = true;
}
break;
}
case RT_ObjCRelease: {
CallInst &CI = cast<CallInst>(Inst);
Value *ArgVal = RC->getSwiftRCIdentityRoot(CI.getArgOperand(0));
// objc_release(null) is a noop, zap it.
if (isa<ConstantPointerNull>(ArgVal)) {
CI.eraseFromParent();
Changed = true;
++NumNoopDeleted;
continue;
}
break;
}
// These retain instructions return their argument so must be processed
// specially.
case RT_BridgeRetain:
case RT_ObjCRetain: {
// Canonicalize the retain so that nothing uses its result.
CallInst &CI = cast<CallInst>(Inst);
// Do not get RC identical value here, could end up with a
// crash in replaceAllUsesWith as the type maybe different.
Value *ArgVal = CI.getArgOperand(0);
if (!CI.use_empty()) {
CI.replaceAllUsesWith(ArgVal);
Changed = true;
}
// {objc_retain,swift_unknownRetain}(null) is a noop, delete it.
if (isa<ConstantPointerNull>(ArgVal)) {
CI.eraseFromParent();
Changed = true;
++NumNoopDeleted;
continue;
}
break;
}
}
}
}
return Changed;
}
