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-rw-r--r--lib/Analysis/LazyCallGraph.cpp673
1 files changed, 610 insertions, 63 deletions
diff --git a/lib/Analysis/LazyCallGraph.cpp b/lib/Analysis/LazyCallGraph.cpp
index ea213f2..e073616 100644
--- a/lib/Analysis/LazyCallGraph.cpp
+++ b/lib/Analysis/LazyCallGraph.cpp
@@ -8,19 +8,22 @@
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/LazyCallGraph.h"
-#include "llvm/ADT/SCCIterator.h"
+#include "llvm/ADT/STLExtras.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/InstVisitor.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/PassManager.h"
+#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
+#define DEBUG_TYPE "lcg"
+
static void findCallees(
SmallVectorImpl<Constant *> &Worklist, SmallPtrSetImpl<Constant *> &Visited,
SmallVectorImpl<PointerUnion<Function *, LazyCallGraph::Node *>> &Callees,
- SmallPtrSetImpl<Function *> &CalleeSet) {
+ DenseMap<Function *, size_t> &CalleeIndexMap) {
while (!Worklist.empty()) {
Constant *C = Worklist.pop_back_val();
@@ -35,8 +38,12 @@ static void findCallees(
// alias. Then a test of the address of the weak function against the new
// strong definition's address would be an effective way to determine the
// safety of optimizing a direct call edge.
- if (!F->isDeclaration() && CalleeSet.insert(F))
+ if (!F->isDeclaration() &&
+ CalleeIndexMap.insert(std::make_pair(F, Callees.size())).second) {
+ DEBUG(dbgs() << " Added callable function: " << F->getName()
+ << "\n");
Callees.push_back(F);
+ }
continue;
}
@@ -46,7 +53,11 @@ static void findCallees(
}
}
-LazyCallGraph::Node::Node(LazyCallGraph &G, Function &F) : G(G), F(F) {
+LazyCallGraph::Node::Node(LazyCallGraph &G, Function &F)
+ : G(&G), F(F), DFSNumber(0), LowLink(0) {
+ DEBUG(dbgs() << " Adding functions called by '" << F.getName()
+ << "' to the graph.\n");
+
SmallVector<Constant *, 16> Worklist;
SmallPtrSet<Constant *, 16> Visited;
// Find all the potential callees in this function. First walk the
@@ -61,36 +72,41 @@ LazyCallGraph::Node::Node(LazyCallGraph &G, Function &F) : G(G), F(F) {
// We've collected all the constant (and thus potentially function or
// function containing) operands to all of the instructions in the function.
// Process them (recursively) collecting every function found.
- findCallees(Worklist, Visited, Callees, CalleeSet);
+ findCallees(Worklist, Visited, Callees, CalleeIndexMap);
}
-LazyCallGraph::Node::Node(LazyCallGraph &G, const Node &OtherN)
- : G(G), F(OtherN.F), CalleeSet(OtherN.CalleeSet) {
- // Loop over the other node's callees, adding the Function*s to our list
- // directly, and recursing to add the Node*s.
- Callees.reserve(OtherN.Callees.size());
- for (const auto &OtherCallee : OtherN.Callees)
- if (Function *Callee = OtherCallee.dyn_cast<Function *>())
- Callees.push_back(Callee);
- else
- Callees.push_back(G.copyInto(*OtherCallee.get<Node *>()));
+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);
}
-LazyCallGraph::Node::Node(LazyCallGraph &G, Node &&OtherN)
- : G(G), F(OtherN.F), Callees(std::move(OtherN.Callees)),
- CalleeSet(std::move(OtherN.CalleeSet)) {
- // Loop over our Callees. They've been moved from another node, but we need
- // to move the Node*s to live under our bump ptr allocator.
- for (auto &Callee : Callees)
- if (Node *ChildN = Callee.dyn_cast<Node *>())
- Callee = G.moveInto(std::move(*ChildN));
+void LazyCallGraph::Node::insertEdgeInternal(Node &CalleeN) {
+ CalleeIndexMap.insert(std::make_pair(&CalleeN.getFunction(), Callees.size()));
+ Callees.push_back(&CalleeN);
}
-LazyCallGraph::LazyCallGraph(Module &M) : M(M) {
+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");
for (Function &F : M)
if (!F.isDeclaration() && !F.hasLocalLinkage())
- if (EntryNodeSet.insert(&F))
+ if (EntryIndexMap.insert(std::make_pair(&F, EntryNodes.size())).second) {
+ DEBUG(dbgs() << " Adding '" << F.getName()
+ << "' to entry set of the graph.\n");
EntryNodes.push_back(&F);
+ }
// Now add entry nodes for functions reachable via initializers to globals.
SmallVector<Constant *, 16> Worklist;
@@ -100,51 +116,568 @@ LazyCallGraph::LazyCallGraph(Module &M) : M(M) {
if (Visited.insert(GV.getInitializer()))
Worklist.push_back(GV.getInitializer());
- findCallees(Worklist, Visited, EntryNodes, EntryNodeSet);
-}
+ DEBUG(dbgs() << " Adding functions referenced by global initializers to the "
+ "entry set.\n");
+ findCallees(Worklist, Visited, EntryNodes, EntryIndexMap);
-LazyCallGraph::LazyCallGraph(const LazyCallGraph &G)
- : M(G.M), EntryNodeSet(G.EntryNodeSet) {
- EntryNodes.reserve(G.EntryNodes.size());
- for (const auto &EntryNode : G.EntryNodes)
- if (Function *Callee = EntryNode.dyn_cast<Function *>())
- EntryNodes.push_back(Callee);
+ 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.push_back(F);
else
- EntryNodes.push_back(copyInto(*EntryNode.get<Node *>()));
+ SCCEntryNodes.push_back(&Entry.get<Node *>()->getFunction());
+ }
}
-// FIXME: This would be crazy simpler if BumpPtrAllocator were movable without
-// invalidating any of the allocated memory. We should make that be the case at
-// some point and delete this.
LazyCallGraph::LazyCallGraph(LazyCallGraph &&G)
- : M(G.M), EntryNodes(std::move(G.EntryNodes)),
- EntryNodeSet(std::move(G.EntryNodeSet)) {
- // Loop over our EntryNodes. They've been moved from another graph, so we
- // need to move the Node*s to live under our bump ptr allocator. We can just
- // do this in-place.
- for (auto &Entry : EntryNodes)
- if (Node *EntryN = Entry.dyn_cast<Node *>())
- Entry = moveInto(std::move(*EntryN));
+ : BPA(std::move(G.BPA)), NodeMap(std::move(G.NodeMap)),
+ EntryNodes(std::move(G.EntryNodes)),
+ EntryIndexMap(std::move(G.EntryIndexMap)), SCCBPA(std::move(G.SCCBPA)),
+ SCCMap(std::move(G.SCCMap)), LeafSCCs(std::move(G.LeafSCCs)),
+ DFSStack(std::move(G.DFSStack)),
+ SCCEntryNodes(std::move(G.SCCEntryNodes)),
+ NextDFSNumber(G.NextDFSNumber) {
+ updateGraphPtrs();
+}
+
+LazyCallGraph &LazyCallGraph::operator=(LazyCallGraph &&G) {
+ BPA = std::move(G.BPA);
+ NodeMap = std::move(G.NodeMap);
+ EntryNodes = std::move(G.EntryNodes);
+ EntryIndexMap = std::move(G.EntryIndexMap);
+ SCCBPA = std::move(G.SCCBPA);
+ SCCMap = std::move(G.SCCMap);
+ LeafSCCs = std::move(G.LeafSCCs);
+ DFSStack = std::move(G.DFSStack);
+ SCCEntryNodes = std::move(G.SCCEntryNodes);
+ NextDFSNumber = G.NextDFSNumber;
+ updateGraphPtrs();
+ 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;
}
-LazyCallGraph::Node *LazyCallGraph::copyInto(const Node &OtherN) {
- Node *&N = NodeMap[&OtherN.F];
- if (N)
- return N;
+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 new (N = BPA.Allocate()) Node(*this, OtherN);
+ return false;
}
-LazyCallGraph::Node *LazyCallGraph::moveInto(Node &&OtherN) {
- Node *&N = NodeMap[&OtherN.F];
- if (N)
- return N;
+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.");
- return new (N = BPA.Allocate()) Node(*this, std::move(OtherN));
+ // 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 &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 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->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);
+
+ 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::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(*this);
+
+ 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!");
+ NewSCC->insert(*NodeStack.pop_back_val());
+ }
+ 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) {
+ SCC &ChildSCC = *SCCMap.lookup(&SCCChildN);
+ if (&ChildSCC == NewSCC)
+ continue;
+ ChildSCC.ParentSCCs.insert(NewSCC);
+ IsLeafSCC = false;
+ }
+
+ // For the SCCs where we fine no child SCCs, add them to the leaf list.
+ if (IsLeafSCC)
+ LeafSCCs.push_back(NewSCC);
+
+ return NewSCC;
+}
+
+LazyCallGraph::SCC *LazyCallGraph::getNextSCCInPostOrder() {
+ 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.
+ 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;
+ }
+
+ for (;;) {
+ assert(N->DFSNumber != 0 && "We should always assign a DFS number "
+ "before placing a node onto the stack.");
+
+ 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.
+ DFSStack.push_back(std::make_pair(N, N->begin()));
+
+ // Recurse onto this node via a tail call.
+ 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 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;
+ }
+
+ if (N->LowLink == N->DFSNumber)
+ // Form the new SCC out of the top of the DFS stack.
+ 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;
@@ -154,9 +687,9 @@ LazyCallGraphPrinterPass::LazyCallGraphPrinterPass(raw_ostream &OS) : OS(OS) {}
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)
@@ -165,6 +698,16 @@ static void printNodes(raw_ostream &OS, LazyCallGraph::Node &N,
OS << "\n";
}
+static void printSCC(raw_ostream &OS, LazyCallGraph::SCC &SCC) {
+ ptrdiff_t SCCSize = std::distance(SCC.begin(), SCC.end());
+ OS << " SCC with " << SCCSize << " functions:\n";
+
+ for (LazyCallGraph::Node *N : SCC)
+ OS << " " << N->getFunction().getName() << "\n";
+
+ OS << "\n";
+}
+
PreservedAnalyses LazyCallGraphPrinterPass::run(Module *M,
ModuleAnalysisManager *AM) {
LazyCallGraph &G = AM->getResult<LazyCallGraphAnalysis>(M);
@@ -173,9 +716,13 @@ PreservedAnalyses LazyCallGraphPrinterPass::run(Module *M,
<< "\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);
return PreservedAnalyses::all();
+
}
generated by cgit v1.1 at 2024-05-21 14:05:20 +0000