1 //===- CGSCCPassManager.cpp - Managing & running CGSCC passes -------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "llvm/Analysis/CGSCCPassManager.h"
11 #include "llvm/ADT/ArrayRef.h"
12 #include "llvm/ADT/Optional.h"
13 #include "llvm/ADT/STLExtras.h"
14 #include "llvm/ADT/SetVector.h"
15 #include "llvm/ADT/SmallPtrSet.h"
16 #include "llvm/ADT/SmallVector.h"
17 #include "llvm/ADT/iterator_range.h"
18 #include "llvm/Analysis/LazyCallGraph.h"
19 #include "llvm/IR/CallSite.h"
20 #include "llvm/IR/Constant.h"
21 #include "llvm/IR/InstIterator.h"
22 #include "llvm/IR/Instruction.h"
23 #include "llvm/IR/PassManager.h"
24 #include "llvm/Support/Casting.h"
25 #include "llvm/Support/Debug.h"
26 #include "llvm/Support/raw_ostream.h"
31 #define DEBUG_TYPE "cgscc"
35 // Explicit template instantiations and specialization defininitions for core
39 // Explicit instantiations for the core proxy templates.
40 template class AllAnalysesOn<LazyCallGraph::SCC>;
41 template class AnalysisManager<LazyCallGraph::SCC, LazyCallGraph &>;
42 template class PassManager<LazyCallGraph::SCC, CGSCCAnalysisManager,
43 LazyCallGraph &, CGSCCUpdateResult &>;
44 template class InnerAnalysisManagerProxy<CGSCCAnalysisManager, Module>;
45 template class OuterAnalysisManagerProxy<ModuleAnalysisManager,
46 LazyCallGraph::SCC, LazyCallGraph &>;
47 template class OuterAnalysisManagerProxy<CGSCCAnalysisManager, Function>;
49 /// Explicitly specialize the pass manager run method to handle call graph
53 PassManager<LazyCallGraph::SCC, CGSCCAnalysisManager, LazyCallGraph &,
54 CGSCCUpdateResult &>::run(LazyCallGraph::SCC &InitialC,
55 CGSCCAnalysisManager &AM,
56 LazyCallGraph &G, CGSCCUpdateResult &UR) {
57 PreservedAnalyses PA = PreservedAnalyses::all();
60 dbgs() << "Starting CGSCC pass manager run.\n";
62 // The SCC may be refined while we are running passes over it, so set up
63 // a pointer that we can update.
64 LazyCallGraph::SCC *C = &InitialC;
66 for (auto &Pass : Passes) {
68 dbgs() << "Running pass: " << Pass->name() << " on " << *C << "\n";
70 PreservedAnalyses PassPA = Pass->run(*C, AM, G, UR);
72 // Update the SCC if necessary.
73 C = UR.UpdatedC ? UR.UpdatedC : C;
75 // If the CGSCC pass wasn't able to provide a valid updated SCC, the
76 // current SCC may simply need to be skipped if invalid.
77 if (UR.InvalidatedSCCs.count(C)) {
78 DEBUG(dbgs() << "Skipping invalidated root or island SCC!\n");
81 // Check that we didn't miss any update scenario.
82 assert(C->begin() != C->end() && "Cannot have an empty SCC!");
84 // Update the analysis manager as each pass runs and potentially
85 // invalidates analyses.
86 AM.invalidate(*C, PassPA);
88 // Finally, we intersect the final preserved analyses to compute the
89 // aggregate preserved set for this pass manager.
90 PA.intersect(std::move(PassPA));
92 // FIXME: Historically, the pass managers all called the LLVM context's
93 // yield function here. We don't have a generic way to acquire the
94 // context and it isn't yet clear what the right pattern is for yielding
95 // in the new pass manager so it is currently omitted.
96 // ...getContext().yield();
99 // Invaliadtion was handled after each pass in the above loop for the current
100 // SCC. Therefore, the remaining analysis results in the AnalysisManager are
101 // preserved. We mark this with a set so that we don't need to inspect each
103 PA.preserveSet<AllAnalysesOn<LazyCallGraph::SCC>>();
106 dbgs() << "Finished CGSCC pass manager run.\n";
111 bool CGSCCAnalysisManagerModuleProxy::Result::invalidate(
112 Module &M, const PreservedAnalyses &PA,
113 ModuleAnalysisManager::Invalidator &Inv) {
114 // If literally everything is preserved, we're done.
115 if (PA.areAllPreserved())
116 return false; // This is still a valid proxy.
118 // If this proxy or the call graph is going to be invalidated, we also need
119 // to clear all the keys coming from that analysis.
121 // We also directly invalidate the FAM's module proxy if necessary, and if
122 // that proxy isn't preserved we can't preserve this proxy either. We rely on
123 // it to handle module -> function analysis invalidation in the face of
124 // structural changes and so if it's unavailable we conservatively clear the
125 // entire SCC layer as well rather than trying to do invalidation ourselves.
126 auto PAC = PA.getChecker<CGSCCAnalysisManagerModuleProxy>();
127 if (!(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Module>>()) ||
128 Inv.invalidate<LazyCallGraphAnalysis>(M, PA) ||
129 Inv.invalidate<FunctionAnalysisManagerModuleProxy>(M, PA)) {
132 // And the proxy itself should be marked as invalid so that we can observe
133 // the new call graph. This isn't strictly necessary because we cheat
134 // above, but is still useful.
138 // Directly check if the relevant set is preserved so we can short circuit
139 // invalidating SCCs below.
140 bool AreSCCAnalysesPreserved =
141 PA.allAnalysesInSetPreserved<AllAnalysesOn<LazyCallGraph::SCC>>();
143 // Ok, we have a graph, so we can propagate the invalidation down into it.
145 for (auto &RC : G->postorder_ref_sccs())
147 Optional<PreservedAnalyses> InnerPA;
149 // Check to see whether the preserved set needs to be adjusted based on
150 // module-level analysis invalidation triggering deferred invalidation
152 if (auto *OuterProxy =
153 InnerAM->getCachedResult<ModuleAnalysisManagerCGSCCProxy>(C))
154 for (const auto &OuterInvalidationPair :
155 OuterProxy->getOuterInvalidations()) {
156 AnalysisKey *OuterAnalysisID = OuterInvalidationPair.first;
157 const auto &InnerAnalysisIDs = OuterInvalidationPair.second;
158 if (Inv.invalidate(OuterAnalysisID, M, PA)) {
161 for (AnalysisKey *InnerAnalysisID : InnerAnalysisIDs)
162 InnerPA->abandon(InnerAnalysisID);
166 // Check if we needed a custom PA set. If so we'll need to run the inner
169 InnerAM->invalidate(C, *InnerPA);
173 // Otherwise we only need to do invalidation if the original PA set didn't
174 // preserve all SCC analyses.
175 if (!AreSCCAnalysesPreserved)
176 InnerAM->invalidate(C, PA);
179 // Return false to indicate that this result is still a valid proxy.
184 CGSCCAnalysisManagerModuleProxy::Result
185 CGSCCAnalysisManagerModuleProxy::run(Module &M, ModuleAnalysisManager &AM) {
186 // Force the Function analysis manager to also be available so that it can
187 // be accessed in an SCC analysis and proxied onward to function passes.
188 // FIXME: It is pretty awkward to just drop the result here and assert that
189 // we can find it again later.
190 (void)AM.getResult<FunctionAnalysisManagerModuleProxy>(M);
192 return Result(*InnerAM, AM.getResult<LazyCallGraphAnalysis>(M));
195 AnalysisKey FunctionAnalysisManagerCGSCCProxy::Key;
197 FunctionAnalysisManagerCGSCCProxy::Result
198 FunctionAnalysisManagerCGSCCProxy::run(LazyCallGraph::SCC &C,
199 CGSCCAnalysisManager &AM,
201 // Collect the FunctionAnalysisManager from the Module layer and use that to
202 // build the proxy result.
204 // This allows us to rely on the FunctionAnalysisMangaerModuleProxy to
205 // invalidate the function analyses.
206 auto &MAM = AM.getResult<ModuleAnalysisManagerCGSCCProxy>(C, CG).getManager();
207 Module &M = *C.begin()->getFunction().getParent();
208 auto *FAMProxy = MAM.getCachedResult<FunctionAnalysisManagerModuleProxy>(M);
209 assert(FAMProxy && "The CGSCC pass manager requires that the FAM module "
210 "proxy is run on the module prior to entering the CGSCC "
213 // Note that we special-case invalidation handling of this proxy in the CGSCC
214 // analysis manager's Module proxy. This avoids the need to do anything
215 // special here to recompute all of this if ever the FAM's module proxy goes
217 return Result(FAMProxy->getManager());
220 bool FunctionAnalysisManagerCGSCCProxy::Result::invalidate(
221 LazyCallGraph::SCC &C, const PreservedAnalyses &PA,
222 CGSCCAnalysisManager::Invalidator &Inv) {
223 // If literally everything is preserved, we're done.
224 if (PA.areAllPreserved())
225 return false; // This is still a valid proxy.
227 // If this proxy isn't marked as preserved, then even if the result remains
228 // valid, the key itself may no longer be valid, so we clear everything.
230 // Note that in order to preserve this proxy, a module pass must ensure that
231 // the FAM has been completely updated to handle the deletion of functions.
232 // Specifically, any FAM-cached results for those functions need to have been
233 // forcibly cleared. When preserved, this proxy will only invalidate results
234 // cached on functions *still in the module* at the end of the module pass.
235 auto PAC = PA.getChecker<FunctionAnalysisManagerCGSCCProxy>();
236 if (!PAC.preserved() && !PAC.preservedSet<AllAnalysesOn<LazyCallGraph::SCC>>()) {
237 for (LazyCallGraph::Node &N : C)
238 FAM->clear(N.getFunction(), N.getFunction().getName());
243 // Directly check if the relevant set is preserved.
244 bool AreFunctionAnalysesPreserved =
245 PA.allAnalysesInSetPreserved<AllAnalysesOn<Function>>();
247 // Now walk all the functions to see if any inner analysis invalidation is
249 for (LazyCallGraph::Node &N : C) {
250 Function &F = N.getFunction();
251 Optional<PreservedAnalyses> FunctionPA;
253 // Check to see whether the preserved set needs to be pruned based on
254 // SCC-level analysis invalidation that triggers deferred invalidation
255 // registered with the outer analysis manager proxy for this function.
256 if (auto *OuterProxy =
257 FAM->getCachedResult<CGSCCAnalysisManagerFunctionProxy>(F))
258 for (const auto &OuterInvalidationPair :
259 OuterProxy->getOuterInvalidations()) {
260 AnalysisKey *OuterAnalysisID = OuterInvalidationPair.first;
261 const auto &InnerAnalysisIDs = OuterInvalidationPair.second;
262 if (Inv.invalidate(OuterAnalysisID, C, PA)) {
265 for (AnalysisKey *InnerAnalysisID : InnerAnalysisIDs)
266 FunctionPA->abandon(InnerAnalysisID);
270 // Check if we needed a custom PA set, and if so we'll need to run the
271 // inner invalidation.
273 FAM->invalidate(F, *FunctionPA);
277 // Otherwise we only need to do invalidation if the original PA set didn't
278 // preserve all function analyses.
279 if (!AreFunctionAnalysesPreserved)
280 FAM->invalidate(F, PA);
283 // Return false to indicate that this result is still a valid proxy.
287 } // end namespace llvm
289 /// When a new SCC is created for the graph and there might be function
290 /// analysis results cached for the functions now in that SCC two forms of
291 /// updates are required.
293 /// First, a proxy from the SCC to the FunctionAnalysisManager needs to be
294 /// created so that any subsequent invalidation events to the SCC are
295 /// propagated to the function analysis results cached for functions within it.
297 /// Second, if any of the functions within the SCC have analysis results with
298 /// outer analysis dependencies, then those dependencies would point to the
299 /// *wrong* SCC's analysis result. We forcibly invalidate the necessary
300 /// function analyses so that they don't retain stale handles.
301 static void updateNewSCCFunctionAnalyses(LazyCallGraph::SCC &C,
303 CGSCCAnalysisManager &AM) {
304 // Get the relevant function analysis manager.
306 AM.getResult<FunctionAnalysisManagerCGSCCProxy>(C, G).getManager();
308 // Now walk the functions in this SCC and invalidate any function analysis
309 // results that might have outer dependencies on an SCC analysis.
310 for (LazyCallGraph::Node &N : C) {
311 Function &F = N.getFunction();
314 FAM.getCachedResult<CGSCCAnalysisManagerFunctionProxy>(F);
316 // No outer analyses were queried, nothing to do.
319 // Forcibly abandon all the inner analyses with dependencies, but
320 // invalidate nothing else.
321 auto PA = PreservedAnalyses::all();
322 for (const auto &OuterInvalidationPair :
323 OuterProxy->getOuterInvalidations()) {
324 const auto &InnerAnalysisIDs = OuterInvalidationPair.second;
325 for (AnalysisKey *InnerAnalysisID : InnerAnalysisIDs)
326 PA.abandon(InnerAnalysisID);
329 // Now invalidate anything we found.
330 FAM.invalidate(F, PA);
334 /// Helper function to update both the \c CGSCCAnalysisManager \p AM and the \c
335 /// CGSCCPassManager's \c CGSCCUpdateResult \p UR based on a range of newly
338 /// The range of new SCCs must be in postorder already. The SCC they were split
339 /// out of must be provided as \p C. The current node being mutated and
340 /// triggering updates must be passed as \p N.
342 /// This function returns the SCC containing \p N. This will be either \p C if
343 /// no new SCCs have been split out, or it will be the new SCC containing \p N.
344 template <typename SCCRangeT>
345 static LazyCallGraph::SCC *
346 incorporateNewSCCRange(const SCCRangeT &NewSCCRange, LazyCallGraph &G,
347 LazyCallGraph::Node &N, LazyCallGraph::SCC *C,
348 CGSCCAnalysisManager &AM, CGSCCUpdateResult &UR) {
349 using SCC = LazyCallGraph::SCC;
351 if (NewSCCRange.begin() == NewSCCRange.end())
354 // Add the current SCC to the worklist as its shape has changed.
355 UR.CWorklist.insert(C);
356 DEBUG(dbgs() << "Enqueuing the existing SCC in the worklist:" << *C << "\n");
360 // Update the current SCC. Note that if we have new SCCs, this must actually
362 assert(C != &*NewSCCRange.begin() &&
363 "Cannot insert new SCCs without changing current SCC!");
364 C = &*NewSCCRange.begin();
365 assert(G.lookupSCC(N) == C && "Failed to update current SCC!");
367 // If we had a cached FAM proxy originally, we will want to create more of
368 // them for each SCC that was split off.
370 AM.getCachedResult<FunctionAnalysisManagerCGSCCProxy>(*OldC) != nullptr;
372 // We need to propagate an invalidation call to all but the newly current SCC
373 // because the outer pass manager won't do that for us after splitting them.
374 // FIXME: We should accept a PreservedAnalysis from the CG updater so that if
375 // there are preserved ananalyses we can avoid invalidating them here for
377 // We know however that this will preserve any FAM proxy so go ahead and mark
379 PreservedAnalyses PA;
380 PA.preserve<FunctionAnalysisManagerCGSCCProxy>();
381 AM.invalidate(*OldC, PA);
383 // Ensure the now-current SCC's function analyses are updated.
385 updateNewSCCFunctionAnalyses(*C, G, AM);
387 for (SCC &NewC : llvm::reverse(make_range(std::next(NewSCCRange.begin()),
388 NewSCCRange.end()))) {
389 assert(C != &NewC && "No need to re-visit the current SCC!");
390 assert(OldC != &NewC && "Already handled the original SCC!");
391 UR.CWorklist.insert(&NewC);
392 DEBUG(dbgs() << "Enqueuing a newly formed SCC:" << NewC << "\n");
394 // Ensure new SCCs' function analyses are updated.
396 updateNewSCCFunctionAnalyses(NewC, G, AM);
398 // Also propagate a normal invalidation to the new SCC as only the current
399 // will get one from the pass manager infrastructure.
400 AM.invalidate(NewC, PA);
405 LazyCallGraph::SCC &llvm::updateCGAndAnalysisManagerForFunctionPass(
406 LazyCallGraph &G, LazyCallGraph::SCC &InitialC, LazyCallGraph::Node &N,
407 CGSCCAnalysisManager &AM, CGSCCUpdateResult &UR) {
408 using Node = LazyCallGraph::Node;
409 using Edge = LazyCallGraph::Edge;
410 using SCC = LazyCallGraph::SCC;
411 using RefSCC = LazyCallGraph::RefSCC;
413 RefSCC &InitialRC = InitialC.getOuterRefSCC();
415 RefSCC *RC = &InitialRC;
416 Function &F = N.getFunction();
418 // Walk the function body and build up the set of retained, promoted, and
420 SmallVector<Constant *, 16> Worklist;
421 SmallPtrSet<Constant *, 16> Visited;
422 SmallPtrSet<Node *, 16> RetainedEdges;
423 SmallSetVector<Node *, 4> PromotedRefTargets;
424 SmallSetVector<Node *, 4> DemotedCallTargets;
426 // First walk the function and handle all called functions. We do this first
427 // because if there is a single call edge, whether there are ref edges is
429 for (Instruction &I : instructions(F))
430 if (auto CS = CallSite(&I))
431 if (Function *Callee = CS.getCalledFunction())
432 if (Visited.insert(Callee).second && !Callee->isDeclaration()) {
433 Node &CalleeN = *G.lookup(*Callee);
434 Edge *E = N->lookup(CalleeN);
435 // FIXME: We should really handle adding new calls. While it will
436 // make downstream usage more complex, there is no fundamental
437 // limitation and it will allow passes within the CGSCC to be a bit
438 // more flexible in what transforms they can do. Until then, we
439 // verify that new calls haven't been introduced.
440 assert(E && "No function transformations should introduce *new* "
441 "call edges! Any new calls should be modeled as "
442 "promoted existing ref edges!");
443 bool Inserted = RetainedEdges.insert(&CalleeN).second;
445 assert(Inserted && "We should never visit a function twice.");
447 PromotedRefTargets.insert(&CalleeN);
450 // Now walk all references.
451 for (Instruction &I : instructions(F))
452 for (Value *Op : I.operand_values())
453 if (auto *C = dyn_cast<Constant>(Op))
454 if (Visited.insert(C).second)
455 Worklist.push_back(C);
457 auto VisitRef = [&](Function &Referee) {
458 Node &RefereeN = *G.lookup(Referee);
459 Edge *E = N->lookup(RefereeN);
460 // FIXME: Similarly to new calls, we also currently preclude
461 // introducing new references. See above for details.
462 assert(E && "No function transformations should introduce *new* ref "
463 "edges! Any new ref edges would require IPO which "
464 "function passes aren't allowed to do!");
465 bool Inserted = RetainedEdges.insert(&RefereeN).second;
467 assert(Inserted && "We should never visit a function twice.");
469 DemotedCallTargets.insert(&RefereeN);
471 LazyCallGraph::visitReferences(Worklist, Visited, VisitRef);
473 // Include synthetic reference edges to known, defined lib functions.
474 for (auto *F : G.getLibFunctions())
475 // While the list of lib functions doesn't have repeats, don't re-visit
476 // anything handled above.
477 if (!Visited.count(F))
480 // First remove all of the edges that are no longer present in this function.
481 // The first step makes these edges uniformly ref edges and accumulates them
482 // into a separate data structure so removal doesn't invalidate anything.
483 SmallVector<Node *, 4> DeadTargets;
485 if (RetainedEdges.count(&E.getNode()))
488 SCC &TargetC = *G.lookupSCC(E.getNode());
489 RefSCC &TargetRC = TargetC.getOuterRefSCC();
490 if (&TargetRC == RC && E.isCall()) {
492 // For separate SCCs this is trivial.
493 RC->switchTrivialInternalEdgeToRef(N, E.getNode());
495 // Now update the call graph.
496 C = incorporateNewSCCRange(RC->switchInternalEdgeToRef(N, E.getNode()),
501 // Now that this is ready for actual removal, put it into our list.
502 DeadTargets.push_back(&E.getNode());
504 // Remove the easy cases quickly and actually pull them out of our list.
506 llvm::remove_if(DeadTargets,
508 SCC &TargetC = *G.lookupSCC(*TargetN);
509 RefSCC &TargetRC = TargetC.getOuterRefSCC();
511 // We can't trivially remove internal targets, so skip
516 RC->removeOutgoingEdge(N, *TargetN);
517 DEBUG(dbgs() << "Deleting outgoing edge from '" << N
518 << "' to '" << TargetN << "'\n");
523 // Now do a batch removal of the internal ref edges left.
524 auto NewRefSCCs = RC->removeInternalRefEdge(N, DeadTargets);
525 if (!NewRefSCCs.empty()) {
526 // The old RefSCC is dead, mark it as such.
527 UR.InvalidatedRefSCCs.insert(RC);
529 // Note that we don't bother to invalidate analyses as ref-edge
530 // connectivity is not really observable in any way and is intended
531 // exclusively to be used for ordering of transforms rather than for
532 // analysis conclusions.
534 // Update RC to the "bottom".
535 assert(G.lookupSCC(N) == C && "Changed the SCC when splitting RefSCCs!");
536 RC = &C->getOuterRefSCC();
537 assert(G.lookupRefSCC(N) == RC && "Failed to update current RefSCC!");
539 // The RC worklist is in reverse postorder, so we enqueue the new ones in
540 // RPO except for the one which contains the source node as that is the
541 // "bottom" we will continue processing in the bottom-up walk.
542 assert(NewRefSCCs.front() == RC &&
543 "New current RefSCC not first in the returned list!");
544 for (RefSCC *NewRC : llvm::reverse(make_range(std::next(NewRefSCCs.begin()),
545 NewRefSCCs.end()))) {
546 assert(NewRC != RC && "Should not encounter the current RefSCC further "
547 "in the postorder list of new RefSCCs.");
548 UR.RCWorklist.insert(NewRC);
549 DEBUG(dbgs() << "Enqueuing a new RefSCC in the update worklist: "
554 // Next demote all the call edges that are now ref edges. This helps make
555 // the SCCs small which should minimize the work below as we don't want to
556 // form cycles that this would break.
557 for (Node *RefTarget : DemotedCallTargets) {
558 SCC &TargetC = *G.lookupSCC(*RefTarget);
559 RefSCC &TargetRC = TargetC.getOuterRefSCC();
561 // The easy case is when the target RefSCC is not this RefSCC. This is
562 // only supported when the target RefSCC is a child of this RefSCC.
563 if (&TargetRC != RC) {
564 assert(RC->isAncestorOf(TargetRC) &&
565 "Cannot potentially form RefSCC cycles here!");
566 RC->switchOutgoingEdgeToRef(N, *RefTarget);
567 DEBUG(dbgs() << "Switch outgoing call edge to a ref edge from '" << N
568 << "' to '" << *RefTarget << "'\n");
572 // We are switching an internal call edge to a ref edge. This may split up
575 // For separate SCCs this is trivial.
576 RC->switchTrivialInternalEdgeToRef(N, *RefTarget);
580 // Now update the call graph.
581 C = incorporateNewSCCRange(RC->switchInternalEdgeToRef(N, *RefTarget), G, N,
585 // Now promote ref edges into call edges.
586 for (Node *CallTarget : PromotedRefTargets) {
587 SCC &TargetC = *G.lookupSCC(*CallTarget);
588 RefSCC &TargetRC = TargetC.getOuterRefSCC();
590 // The easy case is when the target RefSCC is not this RefSCC. This is
591 // only supported when the target RefSCC is a child of this RefSCC.
592 if (&TargetRC != RC) {
593 assert(RC->isAncestorOf(TargetRC) &&
594 "Cannot potentially form RefSCC cycles here!");
595 RC->switchOutgoingEdgeToCall(N, *CallTarget);
596 DEBUG(dbgs() << "Switch outgoing ref edge to a call edge from '" << N
597 << "' to '" << *CallTarget << "'\n");
600 DEBUG(dbgs() << "Switch an internal ref edge to a call edge from '" << N
601 << "' to '" << *CallTarget << "'\n");
603 // Otherwise we are switching an internal ref edge to a call edge. This
604 // may merge away some SCCs, and we add those to the UpdateResult. We also
605 // need to make sure to update the worklist in the event SCCs have moved
606 // before the current one in the post-order sequence
607 bool HasFunctionAnalysisProxy = false;
608 auto InitialSCCIndex = RC->find(*C) - RC->begin();
609 bool FormedCycle = RC->switchInternalEdgeToCall(
610 N, *CallTarget, [&](ArrayRef<SCC *> MergedSCCs) {
611 for (SCC *MergedC : MergedSCCs) {
612 assert(MergedC != &TargetC && "Cannot merge away the target SCC!");
614 HasFunctionAnalysisProxy |=
615 AM.getCachedResult<FunctionAnalysisManagerCGSCCProxy>(
616 *MergedC) != nullptr;
618 // Mark that this SCC will no longer be valid.
619 UR.InvalidatedSCCs.insert(MergedC);
621 // FIXME: We should really do a 'clear' here to forcibly release
622 // memory, but we don't have a good way of doing that and
623 // preserving the function analyses.
624 auto PA = PreservedAnalyses::allInSet<AllAnalysesOn<Function>>();
625 PA.preserve<FunctionAnalysisManagerCGSCCProxy>();
626 AM.invalidate(*MergedC, PA);
630 // If we formed a cycle by creating this call, we need to update more data
634 assert(G.lookupSCC(N) == C && "Failed to update current SCC!");
636 // If one of the invalidated SCCs had a cached proxy to a function
637 // analysis manager, we need to create a proxy in the new current SCC as
638 // the invaliadted SCCs had their functions moved.
639 if (HasFunctionAnalysisProxy)
640 AM.getResult<FunctionAnalysisManagerCGSCCProxy>(*C, G);
642 // Any analyses cached for this SCC are no longer precise as the shape
643 // has changed by introducing this cycle. However, we have taken care to
644 // update the proxies so it remains valide.
645 auto PA = PreservedAnalyses::allInSet<AllAnalysesOn<Function>>();
646 PA.preserve<FunctionAnalysisManagerCGSCCProxy>();
647 AM.invalidate(*C, PA);
649 auto NewSCCIndex = RC->find(*C) - RC->begin();
650 // If we have actually moved an SCC to be topologically "below" the current
651 // one due to merging, we will need to revisit the current SCC after
652 // visiting those moved SCCs.
654 // It is critical that we *do not* revisit the current SCC unless we
655 // actually move SCCs in the process of merging because otherwise we may
656 // form a cycle where an SCC is split apart, merged, split, merged and so
658 if (InitialSCCIndex < NewSCCIndex) {
659 // Put our current SCC back onto the worklist as we'll visit other SCCs
660 // that are now definitively ordered prior to the current one in the
661 // post-order sequence, and may end up observing more precise context to
662 // optimize the current SCC.
663 UR.CWorklist.insert(C);
664 DEBUG(dbgs() << "Enqueuing the existing SCC in the worklist: " << *C
666 // Enqueue in reverse order as we pop off the back of the worklist.
667 for (SCC &MovedC : llvm::reverse(make_range(RC->begin() + InitialSCCIndex,
668 RC->begin() + NewSCCIndex))) {
669 UR.CWorklist.insert(&MovedC);
670 DEBUG(dbgs() << "Enqueuing a newly earlier in post-order SCC: "
676 assert(!UR.InvalidatedSCCs.count(C) && "Invalidated the current SCC!");
677 assert(!UR.InvalidatedRefSCCs.count(RC) && "Invalidated the current RefSCC!");
678 assert(&C->getOuterRefSCC() == RC && "Current SCC not in current RefSCC!");
680 // Record the current RefSCC and SCC for higher layers of the CGSCC pass
681 // manager now that all the updates have been applied.
682 if (RC != &InitialRC)