1//===- CallGraphSCCPass.cpp - Pass that operates BU on call graph ---------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements the CallGraphSCCPass class, which is used for passes
10// which are implemented as bottom-up traversals on the call graph. Because
11// there may be cycles in the call graph, passes of this type operate on the
12// call-graph in SCC order: that is, they process function bottom-up, except for
13// recursive functions, which they process all at once.
14//
15//===----------------------------------------------------------------------===//
16
17#include "llvm/Analysis/CallGraphSCCPass.h"
18#include "llvm/ADT/DenseMap.h"
19#include "llvm/ADT/SCCIterator.h"
20#include "llvm/ADT/Statistic.h"
21#include "llvm/ADT/StringExtras.h"
22#include "llvm/Analysis/CallGraph.h"
23#include "llvm/IR/AbstractCallSite.h"
24#include "llvm/IR/Function.h"
25#include "llvm/IR/Intrinsics.h"
26#include "llvm/IR/LLVMContext.h"
27#include "llvm/IR/LegacyPassManagers.h"
28#include "llvm/IR/Module.h"
29#include "llvm/IR/OptBisect.h"
30#include "llvm/IR/PassTimingInfo.h"
31#include "llvm/IR/PrintPasses.h"
32#include "llvm/Pass.h"
33#include "llvm/Support/CommandLine.h"
34#include "llvm/Support/Debug.h"
35#include "llvm/Support/Timer.h"
36#include "llvm/Support/raw_ostream.h"
37#include <cassert>
38#include <string>
39#include <utility>
40#include <vector>
41
42using namespace llvm;
43
44#define DEBUG_TYPE "cgscc-passmgr"
45
46namespace llvm {
47cl::opt<unsigned> MaxDevirtIterations("max-devirt-iterations", cl::ReallyHidden,
48 cl::init(Val: 4));
49}
50
51STATISTIC(MaxSCCIterations, "Maximum CGSCCPassMgr iterations on one SCC");
52
53//===----------------------------------------------------------------------===//
54// CGPassManager
55//
56/// CGPassManager manages FPPassManagers and CallGraphSCCPasses.
57
58namespace {
59
60class CGPassManager : public ModulePass, public PMDataManager {
61public:
62 static char ID;
63
64 explicit CGPassManager() : ModulePass(ID) {}
65
66 /// Execute all of the passes scheduled for execution. Keep track of
67 /// whether any of the passes modifies the module, and if so, return true.
68 bool runOnModule(Module &M) override;
69
70 using ModulePass::doInitialization;
71 using ModulePass::doFinalization;
72
73 bool doInitialization(CallGraph &CG);
74 bool doFinalization(CallGraph &CG);
75
76 /// Pass Manager itself does not invalidate any analysis info.
77 void getAnalysisUsage(AnalysisUsage &Info) const override {
78 // CGPassManager walks SCC and it needs CallGraph.
79 Info.addRequired<CallGraphWrapperPass>();
80 Info.setPreservesAll();
81 }
82
83 StringRef getPassName() const override { return "CallGraph Pass Manager"; }
84
85 PMDataManager *getAsPMDataManager() override { return this; }
86 Pass *getAsPass() override { return this; }
87
88 // Print passes managed by this manager
89 void dumpPassStructure(unsigned Offset) override {
90 errs().indent(NumSpaces: Offset*2) << "Call Graph SCC Pass Manager\n";
91 for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
92 Pass *P = getContainedPass(N: Index);
93 P->dumpPassStructure(Offset: Offset + 1);
94 dumpLastUses(P, Offset: Offset+1);
95 }
96 }
97
98 Pass *getContainedPass(unsigned N) {
99 assert(N < PassVector.size() && "Pass number out of range!");
100 return static_cast<Pass *>(PassVector[N]);
101 }
102
103 PassManagerType getPassManagerType() const override {
104 return PMT_CallGraphPassManager;
105 }
106
107private:
108 bool RunAllPassesOnSCC(CallGraphSCC &CurSCC, CallGraph &CG,
109 bool &DevirtualizedCall);
110
111 bool RunPassOnSCC(Pass *P, CallGraphSCC &CurSCC,
112 CallGraph &CG, bool &CallGraphUpToDate,
113 bool &DevirtualizedCall);
114 bool RefreshCallGraph(const CallGraphSCC &CurSCC, CallGraph &CG,
115 bool IsCheckingMode);
116};
117
118} // end anonymous namespace.
119
120char CGPassManager::ID = 0;
121
122bool CGPassManager::RunPassOnSCC(Pass *P, CallGraphSCC &CurSCC,
123 CallGraph &CG, bool &CallGraphUpToDate,
124 bool &DevirtualizedCall) {
125 bool Changed = false;
126 PMDataManager *PM = P->getAsPMDataManager();
127 Module &M = CG.getModule();
128
129 if (!PM) {
130 CallGraphSCCPass *CGSP = (CallGraphSCCPass *)P;
131 if (!CallGraphUpToDate) {
132 DevirtualizedCall |= RefreshCallGraph(CurSCC, CG, IsCheckingMode: false);
133 CallGraphUpToDate = true;
134 }
135
136 {
137 unsigned InstrCount, SCCCount = 0;
138 StringMap<std::pair<unsigned, unsigned>> FunctionToInstrCount;
139 bool EmitICRemark = M.shouldEmitInstrCountChangedRemark();
140 TimeRegion PassTimer(getPassTimer(CGSP));
141 if (EmitICRemark)
142 InstrCount = initSizeRemarkInfo(M, FunctionToInstrCount);
143 Changed = CGSP->runOnSCC(SCC&: CurSCC);
144
145 if (EmitICRemark) {
146 // FIXME: Add getInstructionCount to CallGraphSCC.
147 SCCCount = M.getInstructionCount();
148 // Is there a difference in the number of instructions in the module?
149 if (SCCCount != InstrCount) {
150 // Yep. Emit a remark and update InstrCount.
151 int64_t Delta =
152 static_cast<int64_t>(SCCCount) - static_cast<int64_t>(InstrCount);
153 emitInstrCountChangedRemark(P, M, Delta, CountBefore: InstrCount,
154 FunctionToInstrCount);
155 InstrCount = SCCCount;
156 }
157 }
158 }
159
160 // After the CGSCCPass is done, when assertions are enabled, use
161 // RefreshCallGraph to verify that the callgraph was correctly updated.
162#ifndef NDEBUG
163 if (Changed)
164 RefreshCallGraph(CurSCC, CG, IsCheckingMode: true);
165#endif
166
167 return Changed;
168 }
169
170 assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
171 "Invalid CGPassManager member");
172 FPPassManager *FPP = (FPPassManager*)P;
173
174 // Run pass P on all functions in the current SCC.
175 for (CallGraphNode *CGN : CurSCC) {
176 if (Function *F = CGN->getFunction()) {
177 dumpPassInfo(P, S1: EXECUTION_MSG, S2: ON_FUNCTION_MSG, Msg: F->getName());
178 {
179 TimeRegion PassTimer(getPassTimer(FPP));
180 Changed |= FPP->runOnFunction(F&: *F);
181 }
182 F->getContext().yield();
183 }
184 }
185
186 // The function pass(es) modified the IR, they may have clobbered the
187 // callgraph.
188 if (Changed && CallGraphUpToDate) {
189 LLVM_DEBUG(dbgs() << "CGSCCPASSMGR: Pass Dirtied SCC: " << P->getPassName()
190 << '\n');
191 CallGraphUpToDate = false;
192 }
193 return Changed;
194}
195
196/// Scan the functions in the specified CFG and resync the
197/// callgraph with the call sites found in it. This is used after
198/// FunctionPasses have potentially munged the callgraph, and can be used after
199/// CallGraphSCC passes to verify that they correctly updated the callgraph.
200///
201/// This function returns true if it devirtualized an existing function call,
202/// meaning it turned an indirect call into a direct call. This happens when
203/// a function pass like GVN optimizes away stuff feeding the indirect call.
204/// This never happens in checking mode.
205bool CGPassManager::RefreshCallGraph(const CallGraphSCC &CurSCC, CallGraph &CG,
206 bool CheckingMode) {
207 DenseMap<Value *, CallGraphNode *> Calls;
208
209 LLVM_DEBUG(dbgs() << "CGSCCPASSMGR: Refreshing SCC with " << CurSCC.size()
210 << " nodes:\n";
211 for (CallGraphNode *CGN
212 : CurSCC) CGN->dump(););
213
214 bool MadeChange = false;
215 bool DevirtualizedCall = false;
216
217 // Scan all functions in the SCC.
218 unsigned FunctionNo = 0;
219 for (CallGraphSCC::iterator SCCIdx = CurSCC.begin(), E = CurSCC.end();
220 SCCIdx != E; ++SCCIdx, ++FunctionNo) {
221 CallGraphNode *CGN = *SCCIdx;
222 Function *F = CGN->getFunction();
223 if (!F || F->isDeclaration()) continue;
224
225 // Walk the function body looking for call sites. Sync up the call sites in
226 // CGN with those actually in the function.
227
228 // Keep track of the number of direct and indirect calls that were
229 // invalidated and removed.
230 unsigned NumDirectRemoved = 0, NumIndirectRemoved = 0;
231
232 CallGraphNode::iterator CGNEnd = CGN->end();
233
234 auto RemoveAndCheckForDone = [&](CallGraphNode::iterator I) {
235 // Just remove the edge from the set of callees, keep track of whether
236 // I points to the last element of the vector.
237 bool WasLast = I + 1 == CGNEnd;
238 CGN->removeCallEdge(I);
239
240 // If I pointed to the last element of the vector, we have to bail out:
241 // iterator checking rejects comparisons of the resultant pointer with
242 // end.
243 if (WasLast)
244 return true;
245
246 CGNEnd = CGN->end();
247 return false;
248 };
249
250 // Get the set of call sites currently in the function.
251 for (CallGraphNode::iterator I = CGN->begin(); I != CGNEnd;) {
252 // Delete "reference" call records that do not have call instruction. We
253 // reinsert them as needed later. However, keep them in checking mode.
254 if (!I->first) {
255 if (CheckingMode) {
256 ++I;
257 continue;
258 }
259 if (RemoveAndCheckForDone(I))
260 break;
261 continue;
262 }
263
264 // If this call site is null, then the function pass deleted the call
265 // entirely and the WeakTrackingVH nulled it out.
266 auto *Call = dyn_cast_or_null<CallBase>(Val&: *I->first);
267 if (!Call ||
268 // If we've already seen this call site, then the FunctionPass RAUW'd
269 // one call with another, which resulted in two "uses" in the edge
270 // list of the same call.
271 Calls.count(Val: Call)) {
272 assert(!CheckingMode &&
273 "CallGraphSCCPass did not update the CallGraph correctly!");
274
275 // If this was an indirect call site, count it.
276 if (!I->second->getFunction())
277 ++NumIndirectRemoved;
278 else
279 ++NumDirectRemoved;
280
281 if (RemoveAndCheckForDone(I))
282 break;
283 continue;
284 }
285
286 assert(!Calls.count(Call) && "Call site occurs in node multiple times");
287
288 if (Call) {
289 Function *Callee = Call->getCalledFunction();
290 // Ignore intrinsics because they're not really function calls.
291 if (!Callee || !(Callee->isIntrinsic()))
292 Calls.insert(KV: std::make_pair(x&: Call, y&: I->second));
293 }
294 ++I;
295 }
296
297 // Loop over all of the instructions in the function, getting the callsites.
298 // Keep track of the number of direct/indirect calls added.
299 unsigned NumDirectAdded = 0, NumIndirectAdded = 0;
300
301 for (BasicBlock &BB : *F)
302 for (Instruction &I : BB) {
303 auto *Call = dyn_cast<CallBase>(Val: &I);
304 if (!Call)
305 continue;
306 Function *Callee = Call->getCalledFunction();
307 if (Callee && Callee->isIntrinsic())
308 continue;
309
310 // If we are not in checking mode, insert potential callback calls as
311 // references. This is not a requirement but helps to iterate over the
312 // functions in the right order.
313 if (!CheckingMode) {
314 forEachCallbackFunction(CB: *Call, Func: [&](Function *CB) {
315 CGN->addCalledFunction(Call: nullptr, M: CG.getOrInsertFunction(F: CB));
316 });
317 }
318
319 // If this call site already existed in the callgraph, just verify it
320 // matches up to expectations and remove it from Calls.
321 DenseMap<Value *, CallGraphNode *>::iterator ExistingIt =
322 Calls.find(Val: Call);
323 if (ExistingIt != Calls.end()) {
324 CallGraphNode *ExistingNode = ExistingIt->second;
325
326 // Remove from Calls since we have now seen it.
327 Calls.erase(I: ExistingIt);
328
329 // Verify that the callee is right.
330 if (ExistingNode->getFunction() == Call->getCalledFunction())
331 continue;
332
333 // If we are in checking mode, we are not allowed to actually mutate
334 // the callgraph. If this is a case where we can infer that the
335 // callgraph is less precise than it could be (e.g. an indirect call
336 // site could be turned direct), don't reject it in checking mode, and
337 // don't tweak it to be more precise.
338 if (CheckingMode && Call->getCalledFunction() &&
339 ExistingNode->getFunction() == nullptr)
340 continue;
341
342 assert(!CheckingMode &&
343 "CallGraphSCCPass did not update the CallGraph correctly!");
344
345 // If not, we either went from a direct call to indirect, indirect to
346 // direct, or direct to different direct.
347 CallGraphNode *CalleeNode;
348 if (Function *Callee = Call->getCalledFunction()) {
349 CalleeNode = CG.getOrInsertFunction(F: Callee);
350 // Keep track of whether we turned an indirect call into a direct
351 // one.
352 if (!ExistingNode->getFunction()) {
353 DevirtualizedCall = true;
354 LLVM_DEBUG(dbgs() << " CGSCCPASSMGR: Devirtualized call to '"
355 << Callee->getName() << "'\n");
356 }
357 } else {
358 CalleeNode = CG.getCallsExternalNode();
359 }
360
361 // Update the edge target in CGN.
362 CGN->replaceCallEdge(Call&: *Call, NewCall&: *Call, NewNode: CalleeNode);
363 MadeChange = true;
364 continue;
365 }
366
367 assert(!CheckingMode &&
368 "CallGraphSCCPass did not update the CallGraph correctly!");
369
370 // If the call site didn't exist in the CGN yet, add it.
371 CallGraphNode *CalleeNode;
372 if (Function *Callee = Call->getCalledFunction()) {
373 CalleeNode = CG.getOrInsertFunction(F: Callee);
374 ++NumDirectAdded;
375 } else {
376 CalleeNode = CG.getCallsExternalNode();
377 ++NumIndirectAdded;
378 }
379
380 CGN->addCalledFunction(Call, M: CalleeNode);
381 MadeChange = true;
382 }
383
384 // We scanned the old callgraph node, removing invalidated call sites and
385 // then added back newly found call sites. One thing that can happen is
386 // that an old indirect call site was deleted and replaced with a new direct
387 // call. In this case, we have devirtualized a call, and CGSCCPM would like
388 // to iteratively optimize the new code. Unfortunately, we don't really
389 // have a great way to detect when this happens. As an approximation, we
390 // just look at whether the number of indirect calls is reduced and the
391 // number of direct calls is increased. There are tons of ways to fool this
392 // (e.g. DCE'ing an indirect call and duplicating an unrelated block with a
393 // direct call) but this is close enough.
394 if (NumIndirectRemoved > NumIndirectAdded &&
395 NumDirectRemoved < NumDirectAdded)
396 DevirtualizedCall = true;
397
398 // After scanning this function, if we still have entries in callsites, then
399 // they are dangling pointers. WeakTrackingVH should save us for this, so
400 // abort if
401 // this happens.
402 assert(Calls.empty() && "Dangling pointers found in call sites map");
403
404 // Periodically do an explicit clear to remove tombstones when processing
405 // large scc's.
406 if ((FunctionNo & 15) == 15)
407 Calls.clear();
408 }
409
410 LLVM_DEBUG(if (MadeChange) {
411 dbgs() << "CGSCCPASSMGR: Refreshed SCC is now:\n";
412 for (CallGraphNode *CGN : CurSCC)
413 CGN->dump();
414 if (DevirtualizedCall)
415 dbgs() << "CGSCCPASSMGR: Refresh devirtualized a call!\n";
416 } else {
417 dbgs() << "CGSCCPASSMGR: SCC Refresh didn't change call graph.\n";
418 });
419 (void)MadeChange;
420
421 return DevirtualizedCall;
422}
423
424/// Execute the body of the entire pass manager on the specified SCC.
425/// This keeps track of whether a function pass devirtualizes
426/// any calls and returns it in DevirtualizedCall.
427bool CGPassManager::RunAllPassesOnSCC(CallGraphSCC &CurSCC, CallGraph &CG,
428 bool &DevirtualizedCall) {
429 bool Changed = false;
430
431 // Keep track of whether the callgraph is known to be up-to-date or not.
432 // The CGSSC pass manager runs two types of passes:
433 // CallGraphSCC Passes and other random function passes. Because other
434 // random function passes are not CallGraph aware, they may clobber the
435 // call graph by introducing new calls or deleting other ones. This flag
436 // is set to false when we run a function pass so that we know to clean up
437 // the callgraph when we need to run a CGSCCPass again.
438 bool CallGraphUpToDate = true;
439
440 // Run all passes on current SCC.
441 for (unsigned PassNo = 0, e = getNumContainedPasses();
442 PassNo != e; ++PassNo) {
443 Pass *P = getContainedPass(N: PassNo);
444
445 // If we're in -debug-pass=Executions mode, construct the SCC node list,
446 // otherwise avoid constructing this string as it is expensive.
447 if (isPassDebuggingExecutionsOrMore()) {
448 std::string Functions;
449 #ifndef NDEBUG
450 raw_string_ostream OS(Functions);
451 ListSeparator LS;
452 for (const CallGraphNode *CGN : CurSCC) {
453 OS << LS;
454 CGN->print(OS);
455 }
456 OS.flush();
457 #endif
458 dumpPassInfo(P, S1: EXECUTION_MSG, S2: ON_CG_MSG, Msg: Functions);
459 }
460 dumpRequiredSet(P);
461
462 initializeAnalysisImpl(P);
463
464#ifdef EXPENSIVE_CHECKS
465 uint64_t RefHash = P->structuralHash(CG.getModule());
466#endif
467
468 // Actually run this pass on the current SCC.
469 bool LocalChanged =
470 RunPassOnSCC(P, CurSCC, CG, CallGraphUpToDate, DevirtualizedCall);
471
472 Changed |= LocalChanged;
473
474#ifdef EXPENSIVE_CHECKS
475 if (!LocalChanged && (RefHash != P->structuralHash(CG.getModule()))) {
476 llvm::errs() << "Pass modifies its input and doesn't report it: "
477 << P->getPassName() << "\n";
478 llvm_unreachable("Pass modifies its input and doesn't report it");
479 }
480#endif
481 if (LocalChanged)
482 dumpPassInfo(P, S1: MODIFICATION_MSG, S2: ON_CG_MSG, Msg: "");
483 dumpPreservedSet(P);
484
485 verifyPreservedAnalysis(P);
486 if (LocalChanged)
487 removeNotPreservedAnalysis(P);
488 recordAvailableAnalysis(P);
489 removeDeadPasses(P, Msg: "", ON_CG_MSG);
490 }
491
492 // If the callgraph was left out of date (because the last pass run was a
493 // functionpass), refresh it before we move on to the next SCC.
494 if (!CallGraphUpToDate)
495 DevirtualizedCall |= RefreshCallGraph(CurSCC, CG, CheckingMode: false);
496 return Changed;
497}
498
499/// Execute all of the passes scheduled for execution. Keep track of
500/// whether any of the passes modifies the module, and if so, return true.
501bool CGPassManager::runOnModule(Module &M) {
502 CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph();
503 bool Changed = doInitialization(CG);
504
505 // Walk the callgraph in bottom-up SCC order.
506 scc_iterator<CallGraph*> CGI = scc_begin(G: &CG);
507
508 CallGraphSCC CurSCC(CG, &CGI);
509 while (!CGI.isAtEnd()) {
510 // Copy the current SCC and increment past it so that the pass can hack
511 // on the SCC if it wants to without invalidating our iterator.
512 const std::vector<CallGraphNode *> &NodeVec = *CGI;
513 CurSCC.initialize(NewNodes: NodeVec);
514 ++CGI;
515
516 // At the top level, we run all the passes in this pass manager on the
517 // functions in this SCC. However, we support iterative compilation in the
518 // case where a function pass devirtualizes a call to a function. For
519 // example, it is very common for a function pass (often GVN or instcombine)
520 // to eliminate the addressing that feeds into a call. With that improved
521 // information, we would like the call to be an inline candidate, infer
522 // mod-ref information etc.
523 //
524 // Because of this, we allow iteration up to a specified iteration count.
525 // This only happens in the case of a devirtualized call, so we only burn
526 // compile time in the case that we're making progress. We also have a hard
527 // iteration count limit in case there is crazy code.
528 unsigned Iteration = 0;
529 bool DevirtualizedCall = false;
530 do {
531 LLVM_DEBUG(if (Iteration) dbgs()
532 << " SCCPASSMGR: Re-visiting SCC, iteration #" << Iteration
533 << '\n');
534 DevirtualizedCall = false;
535 Changed |= RunAllPassesOnSCC(CurSCC, CG, DevirtualizedCall);
536 } while (Iteration++ < MaxDevirtIterations && DevirtualizedCall);
537
538 if (DevirtualizedCall)
539 LLVM_DEBUG(dbgs() << " CGSCCPASSMGR: Stopped iteration after "
540 << Iteration
541 << " times, due to -max-devirt-iterations\n");
542
543 MaxSCCIterations.updateMax(V: Iteration);
544 }
545 Changed |= doFinalization(CG);
546 return Changed;
547}
548
549/// Initialize CG
550bool CGPassManager::doInitialization(CallGraph &CG) {
551 bool Changed = false;
552 for (unsigned i = 0, e = getNumContainedPasses(); i != e; ++i) {
553 if (PMDataManager *PM = getContainedPass(N: i)->getAsPMDataManager()) {
554 assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
555 "Invalid CGPassManager member");
556 Changed |= ((FPPassManager*)PM)->doInitialization(M&: CG.getModule());
557 } else {
558 Changed |= ((CallGraphSCCPass*)getContainedPass(N: i))->doInitialization(CG);
559 }
560 }
561 return Changed;
562}
563
564/// Finalize CG
565bool CGPassManager::doFinalization(CallGraph &CG) {
566 bool Changed = false;
567 for (unsigned i = 0, e = getNumContainedPasses(); i != e; ++i) {
568 if (PMDataManager *PM = getContainedPass(N: i)->getAsPMDataManager()) {
569 assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
570 "Invalid CGPassManager member");
571 Changed |= ((FPPassManager*)PM)->doFinalization(M&: CG.getModule());
572 } else {
573 Changed |= ((CallGraphSCCPass*)getContainedPass(N: i))->doFinalization(CG);
574 }
575 }
576 return Changed;
577}
578
579//===----------------------------------------------------------------------===//
580// CallGraphSCC Implementation
581//===----------------------------------------------------------------------===//
582
583/// This informs the SCC and the pass manager that the specified
584/// Old node has been deleted, and New is to be used in its place.
585void CallGraphSCC::ReplaceNode(CallGraphNode *Old, CallGraphNode *New) {
586 assert(Old != New && "Should not replace node with self");
587 for (unsigned i = 0; ; ++i) {
588 assert(i != Nodes.size() && "Node not in SCC");
589 if (Nodes[i] != Old) continue;
590 if (New)
591 Nodes[i] = New;
592 else
593 Nodes.erase(position: Nodes.begin() + i);
594 break;
595 }
596
597 // Update the active scc_iterator so that it doesn't contain dangling
598 // pointers to the old CallGraphNode.
599 scc_iterator<CallGraph*> *CGI = (scc_iterator<CallGraph*>*)Context;
600 CGI->ReplaceNode(Old, New);
601}
602
603void CallGraphSCC::DeleteNode(CallGraphNode *Old) {
604 ReplaceNode(Old, /*New=*/nullptr);
605}
606
607//===----------------------------------------------------------------------===//
608// CallGraphSCCPass Implementation
609//===----------------------------------------------------------------------===//
610
611/// Assign pass manager to manage this pass.
612void CallGraphSCCPass::assignPassManager(PMStack &PMS,
613 PassManagerType PreferredType) {
614 // Find CGPassManager
615 while (!PMS.empty() &&
616 PMS.top()->getPassManagerType() > PMT_CallGraphPassManager)
617 PMS.pop();
618
619 assert(!PMS.empty() && "Unable to handle Call Graph Pass");
620 CGPassManager *CGP;
621
622 if (PMS.top()->getPassManagerType() == PMT_CallGraphPassManager)
623 CGP = (CGPassManager*)PMS.top();
624 else {
625 // Create new Call Graph SCC Pass Manager if it does not exist.
626 assert(!PMS.empty() && "Unable to create Call Graph Pass Manager");
627 PMDataManager *PMD = PMS.top();
628
629 // [1] Create new Call Graph Pass Manager
630 CGP = new CGPassManager();
631
632 // [2] Set up new manager's top level manager
633 PMTopLevelManager *TPM = PMD->getTopLevelManager();
634 TPM->addIndirectPassManager(Manager: CGP);
635
636 // [3] Assign manager to manage this new manager. This may create
637 // and push new managers into PMS
638 Pass *P = CGP;
639 TPM->schedulePass(P);
640
641 // [4] Push new manager into PMS
642 PMS.push(PM: CGP);
643 }
644
645 CGP->add(P: this);
646}
647
648/// For this class, we declare that we require and preserve the call graph.
649/// If the derived class implements this method, it should
650/// always explicitly call the implementation here.
651void CallGraphSCCPass::getAnalysisUsage(AnalysisUsage &AU) const {
652 AU.addRequired<CallGraphWrapperPass>();
653 AU.addPreserved<CallGraphWrapperPass>();
654}
655
656//===----------------------------------------------------------------------===//
657// PrintCallGraphPass Implementation
658//===----------------------------------------------------------------------===//
659
660namespace {
661
662 /// PrintCallGraphPass - Print a Module corresponding to a call graph.
663 ///
664 class PrintCallGraphPass : public CallGraphSCCPass {
665 std::string Banner;
666 raw_ostream &OS; // raw_ostream to print on.
667
668 public:
669 static char ID;
670
671 PrintCallGraphPass(const std::string &B, raw_ostream &OS)
672 : CallGraphSCCPass(ID), Banner(B), OS(OS) {}
673
674 void getAnalysisUsage(AnalysisUsage &AU) const override {
675 AU.setPreservesAll();
676 }
677
678 bool runOnSCC(CallGraphSCC &SCC) override {
679 bool BannerPrinted = false;
680 auto PrintBannerOnce = [&]() {
681 if (BannerPrinted)
682 return;
683 OS << Banner;
684 BannerPrinted = true;
685 };
686
687 bool NeedModule = llvm::forcePrintModuleIR();
688 if (isFunctionInPrintList(FunctionName: "*") && NeedModule) {
689 PrintBannerOnce();
690 OS << "\n";
691 SCC.getCallGraph().getModule().print(OS, AAW: nullptr);
692 return false;
693 }
694 bool FoundFunction = false;
695 for (CallGraphNode *CGN : SCC) {
696 if (Function *F = CGN->getFunction()) {
697 if (!F->isDeclaration() && isFunctionInPrintList(FunctionName: F->getName())) {
698 FoundFunction = true;
699 if (!NeedModule) {
700 PrintBannerOnce();
701 F->print(OS);
702 }
703 }
704 } else if (isFunctionInPrintList(FunctionName: "*")) {
705 PrintBannerOnce();
706 OS << "\nPrinting <null> Function\n";
707 }
708 }
709 if (NeedModule && FoundFunction) {
710 PrintBannerOnce();
711 OS << "\n";
712 SCC.getCallGraph().getModule().print(OS, AAW: nullptr);
713 }
714 return false;
715 }
716
717 StringRef getPassName() const override { return "Print CallGraph IR"; }
718 };
719
720} // end anonymous namespace.
721
722char PrintCallGraphPass::ID = 0;
723
724Pass *CallGraphSCCPass::createPrinterPass(raw_ostream &OS,
725 const std::string &Banner) const {
726 return new PrintCallGraphPass(Banner, OS);
727}
728
729static std::string getDescription(const CallGraphSCC &SCC) {
730 std::string Desc = "SCC (";
731 ListSeparator LS;
732 for (CallGraphNode *CGN : SCC) {
733 Desc += LS;
734 Function *F = CGN->getFunction();
735 if (F)
736 Desc += F->getName();
737 else
738 Desc += "<<null function>>";
739 }
740 Desc += ")";
741 return Desc;
742}
743
744bool CallGraphSCCPass::skipSCC(CallGraphSCC &SCC) const {
745 OptPassGate &Gate =
746 SCC.getCallGraph().getModule().getContext().getOptPassGate();
747 return Gate.isEnabled() &&
748 !Gate.shouldRunPass(PassName: this->getPassName(), IRDescription: getDescription(SCC));
749}
750
751char DummyCGSCCPass::ID = 0;
752
753INITIALIZE_PASS(DummyCGSCCPass, "DummyCGSCCPass", "DummyCGSCCPass", false,
754 false)
755

source code of llvm/lib/Analysis/CallGraphSCCPass.cpp