}
for (Value *Op : C->operand_values())
- if (Visited.insert(cast<Constant>(Op)))
+ if (Visited.insert(cast<Constant>(Op)).second)
Worklist.push_back(cast<Constant>(Op));
}
}
for (Instruction &I : BB)
for (Value *Op : I.operand_values())
if (Constant *C = dyn_cast<Constant>(Op))
- if (Visited.insert(C))
+ if (Visited.insert(C).second)
Worklist.push_back(C);
// We've collected all the constant (and thus potentially function or
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");
SmallPtrSet<Constant *, 16> Visited;
for (GlobalVariable &GV : M.globals())
if (GV.hasInitializer())
- if (Visited.insert(GV.getInitializer()))
+ if (Visited.insert(GV.getInitializer()).second)
Worklist.push_back(GV.getInitializer());
DEBUG(dbgs() << " Adding functions referenced by global initializers to the "
"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;
}
-void LazyCallGraph::SCC::removeEdge(LazyCallGraph &G, Function &Caller,
- Function &Callee, SCC &CalleeC) {
- assert(std::find(G.LeafSCCs.begin(), G.LeafSCCs.end(), this) ==
- G.LeafSCCs.end() &&
+void LazyCallGraph::SCC::insert(Node &N) {
+ N.DFSNumber = N.LowLink = -1;
+ Nodes.push_back(&N);
+ G->SCCMap[&N] = this;
+}
+
+bool LazyCallGraph::SCC::isDescendantOf(const SCC &C) const {
+ // Walk up the parents of this SCC and verify that we eventually find C.
+ SmallVector<const SCC *, 4> AncestorWorklist;
+ AncestorWorklist.push_back(this);
+ do {
+ const SCC *AncestorC = AncestorWorklist.pop_back_val();
+ if (AncestorC->isChildOf(C))
+ return true;
+ for (const SCC *ParentC : AncestorC->ParentSCCs)
+ AncestorWorklist.push_back(ParentC);
+ } while (!AncestorWorklist.empty());
+
+ return false;
+}
+
+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::insertOutgoingEdge(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.");
+
+ SCC &CalleeC = *G->SCCMap.lookup(&CalleeN);
+ assert(&CalleeC != this && "Callee must not be in this SCC.");
+ assert(CalleeC.isDescendantOf(*this) &&
+ "Callee must be a descendant of the Caller.");
+
+ // The only change required is to add this SCC to the parent set of the
+ // callee.
+ CalleeC.ParentSCCs.insert(this);
+}
+
+SmallVector<LazyCallGraph::SCC *, 1>
+LazyCallGraph::SCC::insertIncomingEdge(Node &CallerN, Node &CalleeN) {
+ // First insert it into the caller.
+ CallerN.insertEdgeInternal(CalleeN);
+
+ assert(G->SCCMap.lookup(&CalleeN) == this && "Callee must be in this SCC.");
+
+ SCC &CallerC = *G->SCCMap.lookup(&CallerN);
+ assert(&CallerC != this && "Caller must not be in this SCC.");
+ assert(CallerC.isDescendantOf(*this) &&
+ "Caller must be a descendant of the Callee.");
+
+ // The algorithm we use for merging SCCs based on the cycle introduced here
+ // is to walk the SCC inverted DAG formed by the parent SCC sets. The inverse
+ // graph has the same cycle properties as the actual DAG of the SCCs, and
+ // when forming SCCs lazily by a DFS, the bottom of the graph won't exist in
+ // many cases which should prune the search space.
+ //
+ // FIXME: We can get this pruning behavior even after the incremental SCC
+ // formation by leaving behind (conservative) DFS numberings in the nodes,
+ // and pruning the search with them. These would need to be cleverly updated
+ // during the removal of intra-SCC edges, but could be preserved
+ // conservatively.
+
+ // The set of SCCs that are connected to the caller, and thus will
+ // participate in the merged connected component.
+ SmallPtrSet<SCC *, 8> ConnectedSCCs;
+ ConnectedSCCs.insert(this);
+ ConnectedSCCs.insert(&CallerC);
+
+ // We build up a DFS stack of the parents chains.
+ SmallVector<std::pair<SCC *, SCC::parent_iterator>, 8> DFSSCCs;
+ SmallPtrSet<SCC *, 8> VisitedSCCs;
+ int ConnectedDepth = -1;
+ SCC *C = this;
+ parent_iterator I = parent_begin(), E = parent_end();
+ for (;;) {
+ while (I != E) {
+ SCC &ParentSCC = *I++;
+
+ // If we have already processed this parent SCC, skip it, and remember
+ // whether it was connected so we don't have to check the rest of the
+ // stack. This also handles when we reach a child of the 'this' SCC (the
+ // callee) which terminates the search.
+ if (ConnectedSCCs.count(&ParentSCC)) {
+ ConnectedDepth = std::max<int>(ConnectedDepth, DFSSCCs.size());
+ continue;
+ }
+ if (VisitedSCCs.count(&ParentSCC))
+ continue;
+
+ // We fully explore the depth-first space, adding nodes to the connected
+ // set only as we pop them off, so "recurse" by rotating to the parent.
+ DFSSCCs.push_back(std::make_pair(C, I));
+ C = &ParentSCC;
+ I = ParentSCC.parent_begin();
+ E = ParentSCC.parent_end();
+ }
+
+ // If we've found a connection anywhere below this point on the stack (and
+ // thus up the parent graph from the caller), the current node needs to be
+ // added to the connected set now that we've processed all of its parents.
+ if ((int)DFSSCCs.size() == ConnectedDepth) {
+ --ConnectedDepth; // We're finished with this connection.
+ ConnectedSCCs.insert(C);
+ } else {
+ // Otherwise remember that its parents don't ever connect.
+ assert(ConnectedDepth < (int)DFSSCCs.size() &&
+ "Cannot have a connected depth greater than the DFS depth!");
+ VisitedSCCs.insert(C);
+ }
+
+ if (DFSSCCs.empty())
+ break; // We've walked all the parents of the caller transitively.
+
+ // Pop off the prior node and position to unwind the depth first recursion.
+ std::tie(C, I) = DFSSCCs.pop_back_val();
+ E = C->parent_end();
+ }
+
+ // Now that we have identified all of the SCCs which need to be merged into
+ // a connected set with the inserted edge, merge all of them into this SCC.
+ // FIXME: This operation currently creates ordering stability problems
+ // because we don't use stably ordered containers for the parent SCCs or the
+ // connected SCCs.
+ unsigned NewNodeBeginIdx = Nodes.size();
+ for (SCC *C : ConnectedSCCs) {
+ if (C == this)
+ continue;
+ for (SCC *ParentC : C->ParentSCCs)
+ if (!ConnectedSCCs.count(ParentC))
+ ParentSCCs.insert(ParentC);
+ C->ParentSCCs.clear();
+
+ for (Node *N : *C) {
+ for (Node &ChildN : *N) {
+ SCC &ChildC = *G->SCCMap.lookup(&ChildN);
+ if (&ChildC != C)
+ ChildC.ParentSCCs.erase(C);
+ }
+ G->SCCMap[N] = this;
+ Nodes.push_back(N);
+ }
+ C->Nodes.clear();
+ }
+ for (auto I = Nodes.begin() + NewNodeBeginIdx, E = Nodes.end(); I != E; ++I)
+ for (Node &ChildN : **I) {
+ SCC &ChildC = *G->SCCMap.lookup(&ChildN);
+ if (&ChildC != this)
+ ChildC.ParentSCCs.insert(this);
+ }
+
+ // We return the list of SCCs which were merged so that callers can
+ // invalidate any data they have associated with those SCCs. Note that these
+ // SCCs are no longer in an interesting state (they are totally empty) but
+ // the pointers will remain stable for the life of the graph itself.
+ return SmallVector<SCC *, 1>(ConnectedSCCs.begin(), ConnectedSCCs.end());
+}
+
+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 &Callee : *N) {
- SCC &OtherCalleeC = *G.SCCMap.lookup(&Callee);
+ for (Node &OtherCalleeN : *N) {
+ SCC &OtherCalleeC = *G->SCCMap.lookup(&OtherCalleeN);
if (&OtherCalleeC == &CalleeC) {
HasOtherCallToCalleeC = true;
break;
// 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.remove(this);
+ 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 " << Caller.getName() << " -> "
- << Callee.getName() << " edge orphaned the callee's SCC!\n");
+ 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);
+ G->LeafSCCs.push_back(this);
}
-SmallVector<LazyCallGraph::SCC *, 1>
-LazyCallGraph::SCC::removeInternalEdge(LazyCallGraph &G, Node &Caller,
- Node &Callee) {
- // We return a list of the resulting SCCs, where 'this' is always the first
- // element.
- SmallVector<SCC *, 1> ResultSCCs;
- ResultSCCs.push_back(this);
-
- // We're going to do a full mini-Tarjan's walk using a local stack here.
- int NextDFSNumber = 1;
- SmallVector<std::pair<Node *, Node::iterator>, 4> DFSStack;
+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.");
- // The worklist is every node in the original SCC. FIXME: switch the SCC to
- // use a SmallSetVector and swap here.
- SmallSetVector<Node *, 1> Worklist;
- for (Node *N : Nodes) {
- // Clear these to 0 while we re-run Tarjan's over the SCC.
- N->DFSNumber = 0;
- N->LowLink = 0;
- Worklist.insert(N);
- }
+ // 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;
+ }
- // 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.
- SmallSetVector<Node *, 1> NewNodes;
- NewNodes.insert(&Callee);
+ // 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;
+ }
- for (;;) {
- if (DFSStack.empty()) {
- if (Worklist.empty())
- break;
- Node *N = Worklist.pop_back_val();
- DFSStack.push_back(std::make_pair(N, N->begin()));
- }
+ 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));
- Node *N = DFSStack.back().first;
+ // Continue, resetting to the child node.
+ ChildN.LowLink = ChildN.DFSNumber = NextDFSNumber++;
+ N = &ChildN;
+ I = ChildN.begin();
+ E = ChildN.end();
+ continue;
+ }
- // Check if we have reached a node in the new (known connected) set. If so,
- // the entire stack is necessarily in that set and we can re-start.
- if (NewNodes.count(N)) {
- DFSStack.pop_back();
- while (!DFSStack.empty())
- NewNodes.insert(DFSStack.pop_back_val().first);
- continue;
+ // Track the lowest link of the children, 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->DFSNumber == 0) {
- N->LowLink = N->DFSNumber = NextDFSNumber++;
- Worklist.remove(N);
+ 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!");
}
- auto SI = DFSStack.rbegin();
- bool PushedChildNode = false;
- do {
- N = SI->first;
- for (auto I = SI->second, E = N->end(); I != E; ++I) {
- Node &ChildN = *I;
- // 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.
- SCC &ChildSCC = *G.SCCMap.lookup(&ChildN);
- if (&ChildSCC != this) {
- ChildSCC.ParentSCCs.remove(this);
- continue;
- }
+ N = DFSStack.back().first;
+ I = DFSStack.back().second;
+ DFSStack.pop_back();
+ }
+}
- 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;
+SmallVector<LazyCallGraph::SCC *, 1>
+LazyCallGraph::SCC::removeIntraSCCEdge(Node &CallerN, Node &CalleeN) {
+ // First remove it from the node.
+ CallerN.removeEdgeInternal(CalleeN.getFunction());
- // Recurse onto this node via a tail call.
- DFSStack.push_back(std::make_pair(&ChildN, ChildN.begin()));
- PushedChildNode = true;
- break;
- }
+ // We return a list of the resulting *new* SCCs in postorder.
+ SmallVector<SCC *, 1> ResultSCCs;
- // 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;
- }
- if (!PushedChildNode)
- // No more children to process for this stack entry.
- SI->second = N->end();
+ // Direct recursion doesn't impact the SCC graph at all.
+ if (&CallerN == &CalleeN)
+ return ResultSCCs;
- ++SI;
- // If nothing is new on the stack and this isn't the SCC root, walk
- // upward.
- } while (!PushedChildNode && N->LowLink != N->DFSNumber &&
- SI != DFSStack.rend());
+ // 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.");
- if (PushedChildNode)
- continue;
+ // 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);
- // Form the new SCC out of the top of the DFS stack.
- ResultSCCs.push_back(G.formSCCFromDFSStack(DFSStack, SI.base()));
- }
+ // 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);
- // Replace this SCC with the NewNodes we collected above.
- // FIXME: Simplify this when the SCC's datastructure is just a list.
- Nodes.clear();
- NodeSet.clear();
+ 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 : NewNodes) {
- N->DFSNumber = -1;
- N->LowLink = -1;
- Nodes.push_back(N);
- NodeSet.insert(&N->getFunction());
+ for (Node *N : Nodes) {
for (Node &ChildN : *N) {
- if (NewNodes.count(&ChildN))
+ SCC &ChildSCC = *G->SCCMap.lookup(&ChildN);
+ if (&ChildSCC == this)
continue;
- SCC &ChildSCC = *G.SCCMap.lookup(&ChildN);
ChildSCC.ParentSCCs.insert(this);
IsLeafSCC = false;
}
}
#ifndef NDEBUG
- if (ResultSCCs.size() > 1)
+ 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(),
+ 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.size() > 1)
- G.LeafSCCs.erase(std::remove(G.LeafSCCs.begin(), G.LeafSCCs.end(), this),
- G.LeafSCCs.end());
+ 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::removeEdge(Node &CallerN, Function &Callee) {
- auto IndexMapI = CallerN.CalleeIndexMap.find(&Callee);
- assert(IndexMapI != CallerN.CalleeIndexMap.end() &&
- "Callee not in the callee set for the caller?");
-
- Node *CalleeN = CallerN.Callees[IndexMapI->second].dyn_cast<Node *>();
- CallerN.Callees.erase(CallerN.Callees.begin() + IndexMapI->second);
- CallerN.CalleeIndexMap.erase(IndexMapI);
-
- SCC *CallerC = SCCMap.lookup(&CallerN);
- if (!CallerC) {
- // We can only remove edges when the edge isn't actively participating in
- // a DFS walk. Either it must have been popped into an SCC, or it must not
- // yet have been reached by the DFS walk. Assert the latter here.
- assert(std::all_of(DFSStack.begin(), DFSStack.end(),
- [&](const std::pair<Node *, iterator> &StackEntry) {
- return StackEntry.first != &CallerN;
- }) &&
- "Found the caller on the DFSStack!");
- return;
- }
-
- assert(CalleeN && "If the caller is in an SCC, we have to have explored all "
- "its transitively called functions.");
+void LazyCallGraph::insertEdge(Node &CallerN, Function &Callee) {
+ assert(SCCMap.empty() && DFSStack.empty() &&
+ "This method cannot be called after SCCs have been formed!");
- SCC *CalleeC = SCCMap.lookup(CalleeN);
- assert(CalleeC &&
- "The caller has an SCC, and thus by necessity so does the callee.");
+ return CallerN.insertEdgeInternal(Callee);
+}
- // The easy case is when they are different SCCs.
- if (CallerC != CalleeC) {
- CallerC->removeEdge(*this, CallerN.getFunction(), Callee, *CalleeC);
- return;
- }
+void LazyCallGraph::removeEdge(Node &CallerN, Function &Callee) {
+ assert(SCCMap.empty() && DFSStack.empty() &&
+ "This method cannot be called after SCCs have been formed!");
- // The hard case is when we remove an edge within a SCC. This may cause new
- // SCCs to need to be added to the graph.
- CallerC->removeInternalEdge(*this, CallerN, *CalleeN);
+ return CallerN.removeEdgeInternal(Callee);
}
LazyCallGraph::Node &LazyCallGraph::insertInto(Function &F, Node *&MappedN) {
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 (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 (!Callee.isNull())
+ 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] = 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
bool IsLeafSCC = true;
for (Node *SCCN : NewSCC->Nodes)
for (Node &SCCChildN : *SCCN) {
- if (NewSCC->NodeSet.count(&SCCChildN.getFunction()))
- continue;
SCC &ChildSCC = *SCCMap.lookup(&SCCChildN);
+ if (&ChildSCC == NewSCC)
+ continue;
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.
- assert(!SCCMap.count(SI->first) &&
- "Found a node with 0 DFS number but already in an SCC!");
- 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::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.
+ // Track the lowest link of the children, if any are still in the stack.
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;
SmallPtrSetImpl<LazyCallGraph::Node *> &Printed) {
// Recurse depth first through the nodes.
for (LazyCallGraph::Node &ChildN : N)
- if (Printed.insert(&ChildN))
+ if (Printed.insert(&ChildN).second)
printNodes(OS, ChildN, Printed);
OS << " Call edges in function: " << N.getFunction().getName() << "\n";
OS << "\n";
}
-PreservedAnalyses LazyCallGraphPrinterPass::run(Module *M,
+PreservedAnalyses LazyCallGraphPrinterPass::run(Module &M,
ModuleAnalysisManager *AM) {
LazyCallGraph &G = AM->getResult<LazyCallGraphAnalysis>(M);
- OS << "Printing the call graph for module: " << M->getModuleIdentifier()
+ OS << "Printing the call graph for module: " << M.getModuleIdentifier()
<< "\n\n";
SmallPtrSet<LazyCallGraph::Node *, 16> Printed;
for (LazyCallGraph::Node &N : G)
- if (Printed.insert(&N))
+ if (Printed.insert(&N).second)
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