LazyCallGraph::SCC &llvm::updateCGAndAnalysisManagerForFunctionPass(
LazyCallGraph &G, LazyCallGraph::SCC &InitialC, LazyCallGraph::Node &N,
CGSCCAnalysisManager &AM, CGSCCUpdateResult &UR, bool DebugLogging) {
typedef LazyCallGraph::Node Node;
typedef LazyCallGraph::Edge Edge;
typedef LazyCallGraph::SCC SCC;
typedef LazyCallGraph::RefSCC RefSCC;
RefSCC &InitialRC = InitialC.getOuterRefSCC();
SCC *C = &InitialC;
RefSCC *RC = &InitialRC;
Function &F = N.getFunction();
// Walk the function body and build up the set of retained, promoted, and
// demoted edges.
SmallVector<Constant *, 16> Worklist;
SmallPtrSet<Constant *, 16> Visited;
SmallPtrSet<Function *, 16> RetainedEdges;
SmallSetVector<Function *, 4> PromotedRefTargets;
SmallSetVector<Function *, 4> DemotedCallTargets;
// First walk the function and handle all called functions. We do this first
// because if there is a single call edge, whether there are ref edges is
// irrelevant.
for (Instruction &I : instructions(F))
if (auto CS = CallSite(&I))
if (Function *Callee = CS.getCalledFunction())
if (Visited.insert(Callee).second && !Callee->isDeclaration()) {
const Edge *E = N.lookup(*Callee);
// FIXME: We should really handle adding new calls. While it will
// make downstream usage more complex, there is no fundamental
// limitation and it will allow passes within the CGSCC to be a bit
// more flexible in what transforms they can do. Until then, we
// verify that new calls haven't been introduced.
assert(E && "No function transformations should introduce *new* "
"call edges! Any new calls should be modeled as "
"promoted existing ref edges!");
RetainedEdges.insert(Callee);
if (!E->isCall())
PromotedRefTargets.insert(Callee);
}
// Now walk all references.
for (Instruction &I : instructions(F))
for (Value *Op : I.operand_values())
if (Constant *C = dyn_cast<Constant>(Op))
if (Visited.insert(C).second)
Worklist.push_back(C);
LazyCallGraph::visitReferences(Worklist, Visited, [&](Function &Referee) {
const Edge *E = N.lookup(Referee);
// FIXME: Similarly to new calls, we also currently preclude
// introducing new references. See above for details.
assert(E && "No function transformations should introduce *new* ref "
"edges! Any new ref edges would require IPO which "
"function passes aren't allowed to do!");
RetainedEdges.insert(&Referee);
if (E->isCall())
DemotedCallTargets.insert(&Referee);
});
// First remove all of the edges that are no longer present in this function.
// We have to build a list of dead targets first and then remove them as the
// data structures will all be invalidated by removing them.
SmallVector<PointerIntPair<Node *, 1, Edge::Kind>, 4> DeadTargets;
for (Edge &E : N)
if (!RetainedEdges.count(&E.getFunction()))
DeadTargets.push_back({E.getNode(), E.getKind()});
for (auto DeadTarget : DeadTargets) {
Node &TargetN = *DeadTarget.getPointer();
bool IsCall = DeadTarget.getInt() == Edge::Call;
SCC &TargetC = *G.lookupSCC(TargetN);
RefSCC &TargetRC = TargetC.getOuterRefSCC();
if (&TargetRC != RC) {
RC->removeOutgoingEdge(N, TargetN);
if (DebugLogging)
dbgs() << "Deleting outgoing edge from '" << N << "' to '" << TargetN
<< "'\n";
continue;
}
if (DebugLogging)
dbgs() << "Deleting internal " << (IsCall ? "call" : "ref")
<< " edge from '" << N << "' to '" << TargetN << "'\n";
if (IsCall)
C = incorporateNewSCCRange(RC->switchInternalEdgeToRef(N, TargetN), G, N,
C, AM, UR, DebugLogging);
auto NewRefSCCs = RC->removeInternalRefEdge(N, TargetN);
if (!NewRefSCCs.empty()) {
// Note that we don't bother to invalidate analyses as ref-edge
// connectivity is not really observable in any way and is intended
// exclusively to be used for ordering of transforms rather than for
// analysis conclusions.
// The RC worklist is in reverse postorder, so we first enqueue the
// current RefSCC as it will remain the parent of all split RefSCCs, then
// we enqueue the new ones in RPO except for the one which contains the
// source node as that is the "bottom" we will continue processing in the
// bottom-up walk.
UR.RCWorklist.insert(RC);
if (DebugLogging)
dbgs() << "Enqueuing the existing RefSCC in the update worklist: "
<< *RC << "\n";
// Update the RC to the "bottom".
assert(G.lookupSCC(N) == C && "Changed the SCC when splitting RefSCCs!");
RC = &C->getOuterRefSCC();
assert(G.lookupRefSCC(N) == RC && "Failed to update current RefSCC!");
assert(NewRefSCCs.front() == RC &&
"New current RefSCC not first in the returned list!");
for (RefSCC *NewRC : reverse(
make_range(std::next(NewRefSCCs.begin()), NewRefSCCs.end()))) {
assert(NewRC != RC && "Should not encounter the current RefSCC further "
"in the postorder list of new RefSCCs.");
UR.RCWorklist.insert(NewRC);
if (DebugLogging)
dbgs() << "Enqueuing a new RefSCC in the update worklist: " << *NewRC
<< "\n";
}
}
}
// Next demote all the call edges that are now ref edges. This helps make
// the SCCs small which should minimize the work below as we don't want to
// form cycles that this would break.
for (Function *RefTarget : DemotedCallTargets) {
Node &TargetN = *G.lookup(*RefTarget);
SCC &TargetC = *G.lookupSCC(TargetN);
RefSCC &TargetRC = TargetC.getOuterRefSCC();
// The easy case is when the target RefSCC is not this RefSCC. This is
// only supported when the target RefSCC is a child of this RefSCC.
if (&TargetRC != RC) {
assert(RC->isAncestorOf(TargetRC) &&
"Cannot potentially form RefSCC cycles here!");
RC->switchOutgoingEdgeToRef(N, TargetN);
if (DebugLogging)
dbgs() << "Switch outgoing call edge to a ref edge from '" << N
<< "' to '" << TargetN << "'\n";
continue;
}
// Otherwise we are switching an internal call edge to a ref edge. This
// may split up some SCCs.
C = incorporateNewSCCRange(RC->switchInternalEdgeToRef(N, TargetN), G, N, C,
AM, UR, DebugLogging);
}
// Now promote ref edges into call edges.
for (Function *CallTarget : PromotedRefTargets) {
Node &TargetN = *G.lookup(*CallTarget);
SCC &TargetC = *G.lookupSCC(TargetN);
RefSCC &TargetRC = TargetC.getOuterRefSCC();
// The easy case is when the target RefSCC is not this RefSCC. This is
// only supported when the target RefSCC is a child of this RefSCC.
if (&TargetRC != RC) {
assert(RC->isAncestorOf(TargetRC) &&
"Cannot potentially form RefSCC cycles here!");
RC->switchOutgoingEdgeToCall(N, TargetN);
if (DebugLogging)
dbgs() << "Switch outgoing ref edge to a call edge from '" << N
<< "' to '" << TargetN << "'\n";
continue;
}
if (DebugLogging)
dbgs() << "Switch an internal ref edge to a call edge from '" << N
<< "' to '" << TargetN << "'\n";
// Otherwise we are switching an internal ref edge to a call edge. This
// may merge away some SCCs, and we add those to the UpdateResult. We also
// need to make sure to update the worklist in the event SCCs have moved
// before the current one in the post-order sequence.
auto InitialSCCIndex = RC->find(*C) - RC->begin();
auto InvalidatedSCCs = RC->switchInternalEdgeToCall(N, TargetN);
if (!InvalidatedSCCs.empty()) {
C = &TargetC;
assert(G.lookupSCC(N) == C && "Failed to update current SCC!");
// Any analyses cached for this SCC are no longer precise as the shape
// has changed by introducing this cycle.
AM.invalidate(*C, PreservedAnalyses::none());
for (SCC *InvalidatedC : InvalidatedSCCs) {
assert(InvalidatedC != C && "Cannot invalidate the current SCC!");
UR.InvalidatedSCCs.insert(InvalidatedC);
// Also clear any cached analyses for the SCCs that are dead. This
// isn't really necessary for correctness but can release memory.
AM.clear(*InvalidatedC);
}
}
auto NewSCCIndex = RC->find(*C) - RC->begin();
if (InitialSCCIndex < NewSCCIndex) {
// Put our current SCC back onto the worklist as we'll visit other SCCs
// that are now definitively ordered prior to the current one in the
// post-order sequence, and may end up observing more precise context to
// optimize the current SCC.
UR.CWorklist.insert(C);
if (DebugLogging)
dbgs() << "Enqueuing the existing SCC in the worklist: " << *C << "\n";
// Enqueue in reverse order as we pop off the back of the worklist.
for (SCC &MovedC : reverse(make_range(RC->begin() + InitialSCCIndex,
RC->begin() + NewSCCIndex))) {
UR.CWorklist.insert(&MovedC);
if (DebugLogging)
dbgs() << "Enqueuing a newly earlier in post-order SCC: " << MovedC
<< "\n";
}
}
}
assert(!UR.InvalidatedSCCs.count(C) && "Invalidated the current SCC!");
assert(!UR.InvalidatedRefSCCs.count(RC) && "Invalidated the current RefSCC!");
assert(&C->getOuterRefSCC() == RC && "Current SCC not in current RefSCC!");
// Record the current RefSCC and SCC for higher layers of the CGSCC pass
// manager now that all the updates have been applied.
if (RC != &InitialRC)
UR.UpdatedRC = RC;
if (C != &InitialC)
UR.UpdatedC = C;
return *C;
}
LazyCallGraph::SCC &llvm::updateCGAndAnalysisManagerForFunctionPass(
LazyCallGraph &G, LazyCallGraph::SCC &InitialC, LazyCallGraph::Node &N,
CGSCCAnalysisManager &AM, CGSCCUpdateResult &UR) {
using Node = LazyCallGraph::Node;
using Edge = LazyCallGraph::Edge;
using SCC = LazyCallGraph::SCC;
using RefSCC = LazyCallGraph::RefSCC;
RefSCC &InitialRC = InitialC.getOuterRefSCC();
SCC *C = &InitialC;
RefSCC *RC = &InitialRC;
Function &F = N.getFunction();
// Walk the function body and build up the set of retained, promoted, and
// demoted edges.
SmallVector<Constant *, 16> Worklist;
SmallPtrSet<Constant *, 16> Visited;
SmallPtrSet<Node *, 16> RetainedEdges;
SmallSetVector<Node *, 4> PromotedRefTargets;
SmallSetVector<Node *, 4> DemotedCallTargets;
// First walk the function and handle all called functions. We do this first
// because if there is a single call edge, whether there are ref edges is
// irrelevant.
for (Instruction &I : instructions(F))
if (auto CS = CallSite(&I))
if (Function *Callee = CS.getCalledFunction())
if (Visited.insert(Callee).second && !Callee->isDeclaration()) {
Node &CalleeN = *G.lookup(*Callee);
Edge *E = N->lookup(CalleeN);
// FIXME: We should really handle adding new calls. While it will
// make downstream usage more complex, there is no fundamental
// limitation and it will allow passes within the CGSCC to be a bit
// more flexible in what transforms they can do. Until then, we
// verify that new calls haven't been introduced.
assert(E && "No function transformations should introduce *new* "
"call edges! Any new calls should be modeled as "
"promoted existing ref edges!");
bool Inserted = RetainedEdges.insert(&CalleeN).second;
(void)Inserted;
assert(Inserted && "We should never visit a function twice.");
if (!E->isCall())
PromotedRefTargets.insert(&CalleeN);
}
// Now walk all references.
for (Instruction &I : instructions(F))
for (Value *Op : I.operand_values())
if (auto *C = dyn_cast<Constant>(Op))
if (Visited.insert(C).second)
Worklist.push_back(C);
auto VisitRef = [&](Function &Referee) {
Node &RefereeN = *G.lookup(Referee);
Edge *E = N->lookup(RefereeN);
// FIXME: Similarly to new calls, we also currently preclude
// introducing new references. See above for details.
assert(E && "No function transformations should introduce *new* ref "
"edges! Any new ref edges would require IPO which "
"function passes aren't allowed to do!");
bool Inserted = RetainedEdges.insert(&RefereeN).second;
(void)Inserted;
assert(Inserted && "We should never visit a function twice.");
if (E->isCall())
DemotedCallTargets.insert(&RefereeN);
};
LazyCallGraph::visitReferences(Worklist, Visited, VisitRef);
// Include synthetic reference edges to known, defined lib functions.
for (auto *F : G.getLibFunctions())
// While the list of lib functions doesn't have repeats, don't re-visit
// anything handled above.
if (!Visited.count(F))
VisitRef(*F);
// First remove all of the edges that are no longer present in this function.
// The first step makes these edges uniformly ref edges and accumulates them
// into a separate data structure so removal doesn't invalidate anything.
SmallVector<Node *, 4> DeadTargets;
for (Edge &E : *N) {
if (RetainedEdges.count(&E.getNode()))
continue;
SCC &TargetC = *G.lookupSCC(E.getNode());
RefSCC &TargetRC = TargetC.getOuterRefSCC();
if (&TargetRC == RC && E.isCall()) {
if (C != &TargetC) {
// For separate SCCs this is trivial.
RC->switchTrivialInternalEdgeToRef(N, E.getNode());
} else {
// Now update the call graph.
C = incorporateNewSCCRange(RC->switchInternalEdgeToRef(N, E.getNode()),
G, N, C, AM, UR);
}
}
// Now that this is ready for actual removal, put it into our list.
DeadTargets.push_back(&E.getNode());
}
// Remove the easy cases quickly and actually pull them out of our list.
DeadTargets.erase(
llvm::remove_if(DeadTargets,
[&](Node *TargetN) {
SCC &TargetC = *G.lookupSCC(*TargetN);
RefSCC &TargetRC = TargetC.getOuterRefSCC();
// We can't trivially remove internal targets, so skip
// those.
if (&TargetRC == RC)
return false;
RC->removeOutgoingEdge(N, *TargetN);
LLVM_DEBUG(dbgs() << "Deleting outgoing edge from '"
<< N << "' to '" << TargetN << "'\n");
return true;
}),
DeadTargets.end());
// Now do a batch removal of the internal ref edges left.
auto NewRefSCCs = RC->removeInternalRefEdge(N, DeadTargets);
if (!NewRefSCCs.empty()) {
// The old RefSCC is dead, mark it as such.
UR.InvalidatedRefSCCs.insert(RC);
// Note that we don't bother to invalidate analyses as ref-edge
// connectivity is not really observable in any way and is intended
// exclusively to be used for ordering of transforms rather than for
// analysis conclusions.
// Update RC to the "bottom".
assert(G.lookupSCC(N) == C && "Changed the SCC when splitting RefSCCs!");
RC = &C->getOuterRefSCC();
assert(G.lookupRefSCC(N) == RC && "Failed to update current RefSCC!");
// The RC worklist is in reverse postorder, so we enqueue the new ones in
// RPO except for the one which contains the source node as that is the
// "bottom" we will continue processing in the bottom-up walk.
assert(NewRefSCCs.front() == RC &&
"New current RefSCC not first in the returned list!");
for (RefSCC *NewRC : llvm::reverse(make_range(std::next(NewRefSCCs.begin()),
NewRefSCCs.end()))) {
assert(NewRC != RC && "Should not encounter the current RefSCC further "
"in the postorder list of new RefSCCs.");
UR.RCWorklist.insert(NewRC);
LLVM_DEBUG(dbgs() << "Enqueuing a new RefSCC in the update worklist: "
<< *NewRC << "\n");
}
}
// Next demote all the call edges that are now ref edges. This helps make
// the SCCs small which should minimize the work below as we don't want to
// form cycles that this would break.
for (Node *RefTarget : DemotedCallTargets) {
SCC &TargetC = *G.lookupSCC(*RefTarget);
RefSCC &TargetRC = TargetC.getOuterRefSCC();
// The easy case is when the target RefSCC is not this RefSCC. This is
// only supported when the target RefSCC is a child of this RefSCC.
if (&TargetRC != RC) {
assert(RC->isAncestorOf(TargetRC) &&
"Cannot potentially form RefSCC cycles here!");
RC->switchOutgoingEdgeToRef(N, *RefTarget);
LLVM_DEBUG(dbgs() << "Switch outgoing call edge to a ref edge from '" << N
<< "' to '" << *RefTarget << "'\n");
continue;
}
// We are switching an internal call edge to a ref edge. This may split up
// some SCCs.
if (C != &TargetC) {
// For separate SCCs this is trivial.
RC->switchTrivialInternalEdgeToRef(N, *RefTarget);
continue;
}
// Now update the call graph.
C = incorporateNewSCCRange(RC->switchInternalEdgeToRef(N, *RefTarget), G, N,
C, AM, UR);
}
// Now promote ref edges into call edges.
for (Node *CallTarget : PromotedRefTargets) {
SCC &TargetC = *G.lookupSCC(*CallTarget);
RefSCC &TargetRC = TargetC.getOuterRefSCC();
// The easy case is when the target RefSCC is not this RefSCC. This is
// only supported when the target RefSCC is a child of this RefSCC.
if (&TargetRC != RC) {
assert(RC->isAncestorOf(TargetRC) &&
"Cannot potentially form RefSCC cycles here!");
RC->switchOutgoingEdgeToCall(N, *CallTarget);
LLVM_DEBUG(dbgs() << "Switch outgoing ref edge to a call edge from '" << N
<< "' to '" << *CallTarget << "'\n");
continue;
}
LLVM_DEBUG(dbgs() << "Switch an internal ref edge to a call edge from '"
<< N << "' to '" << *CallTarget << "'\n");
// Otherwise we are switching an internal ref edge to a call edge. This
// may merge away some SCCs, and we add those to the UpdateResult. We also
// need to make sure to update the worklist in the event SCCs have moved
// before the current one in the post-order sequence
bool HasFunctionAnalysisProxy = false;
auto InitialSCCIndex = RC->find(*C) - RC->begin();
bool FormedCycle = RC->switchInternalEdgeToCall(
N, *CallTarget, [&](ArrayRef<SCC *> MergedSCCs) {
for (SCC *MergedC : MergedSCCs) {
assert(MergedC != &TargetC && "Cannot merge away the target SCC!");
HasFunctionAnalysisProxy |=
AM.getCachedResult<FunctionAnalysisManagerCGSCCProxy>(
*MergedC) != nullptr;
// Mark that this SCC will no longer be valid.
UR.InvalidatedSCCs.insert(MergedC);
// FIXME: We should really do a 'clear' here to forcibly release
// memory, but we don't have a good way of doing that and
// preserving the function analyses.
auto PA = PreservedAnalyses::allInSet<AllAnalysesOn<Function>>();
PA.preserve<FunctionAnalysisManagerCGSCCProxy>();
AM.invalidate(*MergedC, PA);
}
});
// If we formed a cycle by creating this call, we need to update more data
// structures.
if (FormedCycle) {
C = &TargetC;
assert(G.lookupSCC(N) == C && "Failed to update current SCC!");
// If one of the invalidated SCCs had a cached proxy to a function
// analysis manager, we need to create a proxy in the new current SCC as
// the invalidated SCCs had their functions moved.
if (HasFunctionAnalysisProxy)
AM.getResult<FunctionAnalysisManagerCGSCCProxy>(*C, G);
// Any analyses cached for this SCC are no longer precise as the shape
// has changed by introducing this cycle. However, we have taken care to
// update the proxies so it remains valide.
auto PA = PreservedAnalyses::allInSet<AllAnalysesOn<Function>>();
PA.preserve<FunctionAnalysisManagerCGSCCProxy>();
AM.invalidate(*C, PA);
}
auto NewSCCIndex = RC->find(*C) - RC->begin();
// If we have actually moved an SCC to be topologically "below" the current
// one due to merging, we will need to revisit the current SCC after
// visiting those moved SCCs.
//
// It is critical that we *do not* revisit the current SCC unless we
// actually move SCCs in the process of merging because otherwise we may
// form a cycle where an SCC is split apart, merged, split, merged and so
// on infinitely.
if (InitialSCCIndex < NewSCCIndex) {
// Put our current SCC back onto the worklist as we'll visit other SCCs
// that are now definitively ordered prior to the current one in the
// post-order sequence, and may end up observing more precise context to
// optimize the current SCC.
UR.CWorklist.insert(C);
LLVM_DEBUG(dbgs() << "Enqueuing the existing SCC in the worklist: " << *C
<< "\n");
// Enqueue in reverse order as we pop off the back of the worklist.
for (SCC &MovedC : llvm::reverse(make_range(RC->begin() + InitialSCCIndex,
RC->begin() + NewSCCIndex))) {
UR.CWorklist.insert(&MovedC);
LLVM_DEBUG(dbgs() << "Enqueuing a newly earlier in post-order SCC: "
<< MovedC << "\n");
}
}
}
assert(!UR.InvalidatedSCCs.count(C) && "Invalidated the current SCC!");
assert(!UR.InvalidatedRefSCCs.count(RC) && "Invalidated the current RefSCC!");
assert(&C->getOuterRefSCC() == RC && "Current SCC not in current RefSCC!");
// Record the current RefSCC and SCC for higher layers of the CGSCC pass
// manager now that all the updates have been applied.
if (RC != &InitialRC)
UR.UpdatedRC = RC;
if (C != &InitialC)
UR.UpdatedC = C;
return *C;
}
