findCallees(Worklist, Visited, Callees, CalleeIndexMap);
}
+void LazyCallGraph::Node::insertEdgeInternal(Function &Callee) {
+ if (Node *N = G->lookup(Callee))
+ return insertEdgeInternal(*N);
+
+ CalleeIndexMap.insert(std::make_pair(&Callee, Callees.size()));
+ Callees.push_back(&Callee);
+}
+
+void LazyCallGraph::Node::insertEdgeInternal(Node &CalleeN) {
+ CalleeIndexMap.insert(std::make_pair(&CalleeN.getFunction(), Callees.size()));
+ Callees.push_back(&CalleeN);
+}
+
+void LazyCallGraph::Node::removeEdgeInternal(Function &Callee) {
+ auto IndexMapI = CalleeIndexMap.find(&Callee);
+ assert(IndexMapI != CalleeIndexMap.end() &&
+ "Callee not in the callee set for this caller?");
+
+ Callees[IndexMapI->second] = nullptr;
+ CalleeIndexMap.erase(IndexMapI);
+}
+
LazyCallGraph::LazyCallGraph(Module &M) : NextDFSNumber(0) {
DEBUG(dbgs() << "Building CG for module: " << M.getModuleIdentifier()
<< "\n");
"entry set.\n");
findCallees(Worklist, Visited, EntryNodes, EntryIndexMap);
- for (auto &Entry : EntryNodes)
+ for (auto &Entry : EntryNodes) {
+ assert(!Entry.isNull() &&
+ "We can't have removed edges before we finish the constructor!");
if (Function *F = Entry.dyn_cast<Function *>())
- SCCEntryNodes.insert(F);
+ SCCEntryNodes.push_back(F);
else
- SCCEntryNodes.insert(&Entry.get<Node *>()->getFunction());
+ SCCEntryNodes.push_back(&Entry.get<Node *>()->getFunction());
+ }
}
LazyCallGraph::LazyCallGraph(LazyCallGraph &&G)
return *this;
}
-LazyCallGraph::Node *LazyCallGraph::insertInto(Function &F, Node *&MappedN) {
- return new (MappedN = BPA.Allocate()) Node(*this, F);
+void LazyCallGraph::SCC::insert(Node &N) {
+ N.DFSNumber = N.LowLink = -1;
+ Nodes.push_back(&N);
+ G->SCCMap[&N] = this;
+}
+
+void LazyCallGraph::SCC::insertIntraSCCEdge(Node &CallerN, Node &CalleeN) {
+ // First insert it into the caller.
+ CallerN.insertEdgeInternal(CalleeN);
+
+ assert(G->SCCMap.lookup(&CallerN) == this && "Caller must be in this SCC.");
+ assert(G->SCCMap.lookup(&CalleeN) == this && "Callee must be in this SCC.");
+
+ // Nothing changes about this SCC or any other.
+}
+
+void LazyCallGraph::SCC::removeInterSCCEdge(Node &CallerN, Node &CalleeN) {
+ // First remove it from the node.
+ CallerN.removeEdgeInternal(CalleeN.getFunction());
+
+ assert(G->SCCMap.lookup(&CallerN) == this &&
+ "The caller must be a member of this SCC.");
+
+ SCC &CalleeC = *G->SCCMap.lookup(&CalleeN);
+ assert(&CalleeC != this &&
+ "This API only supports the rmoval of inter-SCC edges.");
+
+ assert(std::find(G->LeafSCCs.begin(), G->LeafSCCs.end(), this) ==
+ G->LeafSCCs.end() &&
+ "Cannot have a leaf SCC caller with a different SCC callee.");
+
+ bool HasOtherCallToCalleeC = false;
+ bool HasOtherCallOutsideSCC = false;
+ for (Node *N : *this) {
+ for (Node &OtherCalleeN : *N) {
+ SCC &OtherCalleeC = *G->SCCMap.lookup(&OtherCalleeN);
+ if (&OtherCalleeC == &CalleeC) {
+ HasOtherCallToCalleeC = true;
+ break;
+ }
+ if (&OtherCalleeC != this)
+ HasOtherCallOutsideSCC = true;
+ }
+ if (HasOtherCallToCalleeC)
+ break;
+ }
+ // Because the SCCs form a DAG, deleting such an edge cannot change the set
+ // of SCCs in the graph. However, it may cut an edge of the SCC DAG, making
+ // the caller no longer a parent of the callee. Walk the other call edges
+ // in the caller to tell.
+ if (!HasOtherCallToCalleeC) {
+ bool Removed = CalleeC.ParentSCCs.erase(this);
+ (void)Removed;
+ assert(Removed &&
+ "Did not find the caller SCC in the callee SCC's parent list!");
+
+ // It may orphan an SCC if it is the last edge reaching it, but that does
+ // not violate any invariants of the graph.
+ if (CalleeC.ParentSCCs.empty())
+ DEBUG(dbgs() << "LCG: Update removing " << CallerN.getFunction().getName()
+ << " -> " << CalleeN.getFunction().getName()
+ << " edge orphaned the callee's SCC!\n");
+ }
+
+ // It may make the Caller SCC a leaf SCC.
+ if (!HasOtherCallOutsideSCC)
+ G->LeafSCCs.push_back(this);
+}
+
+void LazyCallGraph::SCC::internalDFS(
+ SmallVectorImpl<std::pair<Node *, Node::iterator>> &DFSStack,
+ SmallVectorImpl<Node *> &PendingSCCStack, Node *N,
+ SmallVectorImpl<SCC *> &ResultSCCs) {
+ Node::iterator I = N->begin();
+ N->LowLink = N->DFSNumber = 1;
+ int NextDFSNumber = 2;
+ for (;;) {
+ assert(N->DFSNumber != 0 && "We should always assign a DFS number "
+ "before processing a node.");
+
+ // We simulate recursion by popping out of the nested loop and continuing.
+ Node::iterator E = N->end();
+ while (I != E) {
+ Node &ChildN = *I;
+ if (SCC *ChildSCC = G->SCCMap.lookup(&ChildN)) {
+ // Check if we have reached a node in the new (known connected) set of
+ // this SCC. If so, the entire stack is necessarily in that set and we
+ // can re-start.
+ if (ChildSCC == this) {
+ insert(*N);
+ while (!PendingSCCStack.empty())
+ insert(*PendingSCCStack.pop_back_val());
+ while (!DFSStack.empty())
+ insert(*DFSStack.pop_back_val().first);
+ return;
+ }
+
+ // If this child isn't currently in this SCC, no need to process it.
+ // However, we do need to remove this SCC from its SCC's parent set.
+ ChildSCC->ParentSCCs.erase(this);
+ ++I;
+ continue;
+ }
+
+ if (ChildN.DFSNumber == 0) {
+ // Mark that we should start at this child when next this node is the
+ // top of the stack. We don't start at the next child to ensure this
+ // child's lowlink is reflected.
+ DFSStack.push_back(std::make_pair(N, I));
+
+ // Continue, resetting to the child node.
+ ChildN.LowLink = ChildN.DFSNumber = NextDFSNumber++;
+ N = &ChildN;
+ I = ChildN.begin();
+ E = ChildN.end();
+ continue;
+ }
+
+ // Track the lowest link of the childen, if any are still in the stack.
+ // Any child not on the stack will have a LowLink of -1.
+ assert(ChildN.LowLink != 0 &&
+ "Low-link must not be zero with a non-zero DFS number.");
+ if (ChildN.LowLink >= 0 && ChildN.LowLink < N->LowLink)
+ N->LowLink = ChildN.LowLink;
+ ++I;
+ }
+
+ if (N->LowLink == N->DFSNumber) {
+ ResultSCCs.push_back(G->formSCC(N, PendingSCCStack));
+ if (DFSStack.empty())
+ return;
+ } else {
+ // At this point we know that N cannot ever be an SCC root. Its low-link
+ // is not its dfs-number, and we've processed all of its children. It is
+ // just sitting here waiting until some node further down the stack gets
+ // low-link == dfs-number and pops it off as well. Move it to the pending
+ // stack which is pulled into the next SCC to be formed.
+ PendingSCCStack.push_back(N);
+
+ assert(!DFSStack.empty() && "We shouldn't have an empty stack!");
+ }
+
+ N = DFSStack.back().first;
+ I = DFSStack.back().second;
+ DFSStack.pop_back();
+ }
+}
+
+SmallVector<LazyCallGraph::SCC *, 1>
+LazyCallGraph::SCC::removeIntraSCCEdge(Node &CallerN,
+ Node &CalleeN) {
+ // First remove it from the node.
+ CallerN.removeEdgeInternal(CalleeN.getFunction());
+
+ // We return a list of the resulting *new* SCCs in postorder.
+ SmallVector<SCC *, 1> ResultSCCs;
+
+ // Direct recursion doesn't impact the SCC graph at all.
+ if (&CallerN == &CalleeN)
+ return ResultSCCs;
+
+ // The worklist is every node in the original SCC.
+ SmallVector<Node *, 1> Worklist;
+ Worklist.swap(Nodes);
+ for (Node *N : Worklist) {
+ // The nodes formerly in this SCC are no longer in any SCC.
+ N->DFSNumber = 0;
+ N->LowLink = 0;
+ G->SCCMap.erase(N);
+ }
+ assert(Worklist.size() > 1 && "We have to have at least two nodes to have an "
+ "edge between them that is within the SCC.");
+
+ // The callee can already reach every node in this SCC (by definition). It is
+ // the only node we know will stay inside this SCC. Everything which
+ // transitively reaches Callee will also remain in the SCC. To model this we
+ // incrementally add any chain of nodes which reaches something in the new
+ // node set to the new node set. This short circuits one side of the Tarjan's
+ // walk.
+ insert(CalleeN);
+
+ // We're going to do a full mini-Tarjan's walk using a local stack here.
+ SmallVector<std::pair<Node *, Node::iterator>, 4> DFSStack;
+ SmallVector<Node *, 4> PendingSCCStack;
+ do {
+ Node *N = Worklist.pop_back_val();
+ if (N->DFSNumber == 0)
+ internalDFS(DFSStack, PendingSCCStack, N, ResultSCCs);
+
+ assert(DFSStack.empty() && "Didn't flush the entire DFS stack!");
+ assert(PendingSCCStack.empty() && "Didn't flush all pending SCC nodes!");
+ } while (!Worklist.empty());
+
+ // Now we need to reconnect the current SCC to the graph.
+ bool IsLeafSCC = true;
+ for (Node *N : Nodes) {
+ for (Node &ChildN : *N) {
+ SCC &ChildSCC = *G->SCCMap.lookup(&ChildN);
+ if (&ChildSCC == this)
+ continue;
+ ChildSCC.ParentSCCs.insert(this);
+ IsLeafSCC = false;
+ }
+ }
+#ifndef NDEBUG
+ if (!ResultSCCs.empty())
+ assert(!IsLeafSCC && "This SCC cannot be a leaf as we have split out new "
+ "SCCs by removing this edge.");
+ if (!std::any_of(G->LeafSCCs.begin(), G->LeafSCCs.end(),
+ [&](SCC *C) { return C == this; }))
+ assert(!IsLeafSCC && "This SCC cannot be a leaf as it already had child "
+ "SCCs before we removed this edge.");
+#endif
+ // If this SCC stopped being a leaf through this edge removal, remove it from
+ // the leaf SCC list.
+ if (!IsLeafSCC && !ResultSCCs.empty())
+ G->LeafSCCs.erase(std::remove(G->LeafSCCs.begin(), G->LeafSCCs.end(), this),
+ G->LeafSCCs.end());
+
+ // Return the new list of SCCs.
+ return ResultSCCs;
+}
+
+void LazyCallGraph::insertEdge(Node &CallerN, Function &Callee) {
+ assert(SCCMap.empty() && DFSStack.empty() &&
+ "This method cannot be called after SCCs have been formed!");
+
+ return CallerN.insertEdgeInternal(Callee);
+}
+
+void LazyCallGraph::removeEdge(Node &CallerN, Function &Callee) {
+ assert(SCCMap.empty() && DFSStack.empty() &&
+ "This method cannot be called after SCCs have been formed!");
+
+ return CallerN.removeEdgeInternal(Callee);
+}
+
+LazyCallGraph::Node &LazyCallGraph::insertInto(Function &F, Node *&MappedN) {
+ return *new (MappedN = BPA.Allocate()) Node(*this, F);
}
void LazyCallGraph::updateGraphPtrs() {
// Process all nodes updating the graph pointers.
- SmallVector<Node *, 16> Worklist;
- for (auto &Entry : EntryNodes)
- if (Node *EntryN = Entry.dyn_cast<Node *>())
- Worklist.push_back(EntryN);
+ {
+ SmallVector<Node *, 16> Worklist;
+ for (auto &Entry : EntryNodes)
+ if (Node *EntryN = Entry.dyn_cast<Node *>())
+ Worklist.push_back(EntryN);
+
+ while (!Worklist.empty()) {
+ Node *N = Worklist.pop_back_val();
+ N->G = this;
+ for (auto &Callee : N->Callees)
+ if (!Callee.isNull())
+ if (Node *CalleeN = Callee.dyn_cast<Node *>())
+ Worklist.push_back(CalleeN);
+ }
+ }
- while (!Worklist.empty()) {
- Node *N = Worklist.pop_back_val();
- N->G = this;
- for (auto &Callee : N->Callees)
- if (Node *CalleeN = Callee.dyn_cast<Node *>())
- Worklist.push_back(CalleeN);
+ // Process all SCCs updating the graph pointers.
+ {
+ SmallVector<SCC *, 16> Worklist(LeafSCCs.begin(), LeafSCCs.end());
+
+ while (!Worklist.empty()) {
+ SCC *C = Worklist.pop_back_val();
+ C->G = this;
+ Worklist.insert(Worklist.end(), C->ParentSCCs.begin(),
+ C->ParentSCCs.end());
+ }
}
}
-LazyCallGraph::SCC *LazyCallGraph::formSCCFromDFSStack(
- SmallVectorImpl<std::pair<Node *, Node::iterator>> &DFSStack,
- SmallVectorImpl<std::pair<Node *, Node::iterator>>::iterator SCCBegin) {
+LazyCallGraph::SCC *LazyCallGraph::formSCC(Node *RootN,
+ SmallVectorImpl<Node *> &NodeStack) {
// The tail of the stack is the new SCC. Allocate the SCC and pop the stack
// into it.
- SCC *NewSCC = new (SCCBPA.Allocate()) SCC();
+ SCC *NewSCC = new (SCCBPA.Allocate()) SCC(*this);
- for (auto I = SCCBegin, E = DFSStack.end(); I != E; ++I) {
- Node *SCCN = I->first;
- assert(SCCN->LowLink >= SCCBegin->first->LowLink &&
+ while (!NodeStack.empty() && NodeStack.back()->DFSNumber > RootN->DFSNumber) {
+ assert(NodeStack.back()->LowLink >= RootN->LowLink &&
"We cannot have a low link in an SCC lower than its root on the "
"stack!");
-
- SCCMap[&SCCN->getFunction()] = NewSCC;
- NewSCC->Nodes.push_back(SCCN);
- bool Inserted =
- NewSCC->NodeSet.insert(&SCCN->getFunction());
- (void)Inserted;
- assert(Inserted && "Cannot have duplicates in the DFSStack!");
+ NewSCC->insert(*NodeStack.pop_back_val());
}
- DFSStack.erase(SCCBegin, DFSStack.end());
+ NewSCC->insert(*RootN);
// A final pass over all edges in the SCC (this remains linear as we only
// do this once when we build the SCC) to connect it to the parent sets of
// its children.
bool IsLeafSCC = true;
for (Node *SCCN : NewSCC->Nodes)
- for (Node *SCCChildN : *SCCN) {
- if (NewSCC->NodeSet.count(&SCCChildN->getFunction()))
+ for (Node &SCCChildN : *SCCN) {
+ if (SCCMap.lookup(&SCCChildN) == NewSCC)
continue;
- SCC *ChildSCC = SCCMap.lookup(&SCCChildN->getFunction());
- assert(ChildSCC &&
- "Must have all child SCCs processed when building a new SCC!");
- ChildSCC->ParentSCCs.insert(NewSCC);
+ SCC &ChildSCC = *SCCMap.lookup(&SCCChildN);
+ ChildSCC.ParentSCCs.insert(NewSCC);
IsLeafSCC = false;
}
}
LazyCallGraph::SCC *LazyCallGraph::getNextSCCInPostOrder() {
- // When the stack is empty, there are no more SCCs to walk in this graph.
- if (DFSStack.empty()) {
+ Node *N;
+ Node::iterator I;
+ if (!DFSStack.empty()) {
+ N = DFSStack.back().first;
+ I = DFSStack.back().second;
+ DFSStack.pop_back();
+ } else {
// If we've handled all candidate entry nodes to the SCC forest, we're done.
- if (SCCEntryNodes.empty())
- return nullptr;
-
- // Reset the DFS numbering.
- NextDFSNumber = 1;
- Node *N = get(*SCCEntryNodes.pop_back_val());
- DFSStack.push_back(std::make_pair(N, N->begin()));
+ do {
+ if (SCCEntryNodes.empty())
+ return nullptr;
+
+ N = &get(*SCCEntryNodes.pop_back_val());
+ } while (N->DFSNumber != 0);
+ I = N->begin();
+ N->LowLink = N->DFSNumber = 1;
+ NextDFSNumber = 2;
}
- auto SI = DFSStack.rbegin();
- if (SI->first->DFSNumber == 0) {
- // This node hasn't been visited before, assign it a DFS number and remove
- // it from the entry set.
- SI->first->LowLink = SI->first->DFSNumber = NextDFSNumber++;
- SCCEntryNodes.remove(&SI->first->getFunction());
- }
+ for (;;) {
+ assert(N->DFSNumber != 0 && "We should always assign a DFS number "
+ "before placing a node onto the stack.");
- do {
- Node *N = SI->first;
- for (auto I = SI->second, E = N->end(); I != E; ++I) {
- Node *ChildN = *I;
- if (ChildN->DFSNumber == 0) {
+ Node::iterator E = N->end();
+ while (I != E) {
+ Node &ChildN = *I;
+ if (ChildN.DFSNumber == 0) {
// Mark that we should start at this child when next this node is the
// top of the stack. We don't start at the next child to ensure this
// child's lowlink is reflected.
- SI->second = I;
+ DFSStack.push_back(std::make_pair(N, N->begin()));
// Recurse onto this node via a tail call.
- DFSStack.push_back(std::make_pair(ChildN, ChildN->begin()));
- return LazyCallGraph::getNextSCCInPostOrder();
+ assert(!SCCMap.count(&ChildN) &&
+ "Found a node with 0 DFS number but already in an SCC!");
+ ChildN.LowLink = ChildN.DFSNumber = NextDFSNumber++;
+ N = &ChildN;
+ I = ChildN.begin();
+ E = ChildN.end();
+ continue;
}
// Track the lowest link of the childen, if any are still in the stack.
- if (ChildN->LowLink < N->LowLink && !SCCMap.count(&ChildN->getFunction()))
- N->LowLink = ChildN->LowLink;
+ assert(ChildN.LowLink != 0 &&
+ "Low-link must not be zero with a non-zero DFS number.");
+ if (ChildN.LowLink >= 0 && ChildN.LowLink < N->LowLink)
+ N->LowLink = ChildN.LowLink;
+ ++I;
}
- // No more children to process for this stack entry.
- SI->second = N->end();
if (N->LowLink == N->DFSNumber)
// Form the new SCC out of the top of the DFS stack.
- return formSCCFromDFSStack(DFSStack, std::prev(SI.base()));
-
- ++SI;
- } while (SI != DFSStack.rend());
-
- llvm_unreachable(
- "We cannot reach the bottom of the stack without popping an SCC.");
+ return formSCC(N, PendingSCCStack);
+
+ // At this point we know that N cannot ever be an SCC root. Its low-link
+ // is not its dfs-number, and we've processed all of its children. It is
+ // just sitting here waiting until some node further down the stack gets
+ // low-link == dfs-number and pops it off as well. Move it to the pending
+ // stack which is pulled into the next SCC to be formed.
+ PendingSCCStack.push_back(N);
+
+ assert(!DFSStack.empty() && "We never found a viable root!");
+ N = DFSStack.back().first;
+ I = DFSStack.back().second;
+ DFSStack.pop_back();
+ }
}
char LazyCallGraphAnalysis::PassID;
static void printNodes(raw_ostream &OS, LazyCallGraph::Node &N,
SmallPtrSetImpl<LazyCallGraph::Node *> &Printed) {
// Recurse depth first through the nodes.
- for (LazyCallGraph::Node *ChildN : N)
- if (Printed.insert(ChildN))
- printNodes(OS, *ChildN, Printed);
+ for (LazyCallGraph::Node &ChildN : N)
+ if (Printed.insert(&ChildN))
+ printNodes(OS, ChildN, Printed);
OS << " Call edges in function: " << N.getFunction().getName() << "\n";
for (LazyCallGraph::iterator I = N.begin(), E = N.end(); I != E; ++I)
<< "\n\n";
SmallPtrSet<LazyCallGraph::Node *, 16> Printed;
- for (LazyCallGraph::Node *N : G)
- if (Printed.insert(N))
- printNodes(OS, *N, Printed);
+ for (LazyCallGraph::Node &N : G)
+ if (Printed.insert(&N))
+ printNodes(OS, N, Printed);
- for (LazyCallGraph::SCC *SCC : G.postorder_sccs())
- printSCC(OS, *SCC);
+ for (LazyCallGraph::SCC &SCC : G.postorder_sccs())
+ printSCC(OS, SCC);
return PreservedAnalyses::all();
projects / oota-llvm.git / blobdiff