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