1//===- Inliner.cpp - Code common to all inliners --------------------------===// 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 mechanics required to implement inlining without 11// missing any calls and updating the call graph. The decisions of which calls 12// are profitable to inline are implemented elsewhere. 13// 14//===----------------------------------------------------------------------===// 15 16#define DEBUG_TYPE "inline" 17#include "llvm/Transforms/IPO/InlinerPass.h" 18#include "llvm/ADT/SmallPtrSet.h" 19#include "llvm/ADT/Statistic.h" 20#include "llvm/Analysis/CallGraph.h" 21#include "llvm/Analysis/InlineCost.h" 22#include "llvm/IR/DataLayout.h" 23#include "llvm/IR/Instructions.h" 24#include "llvm/IR/IntrinsicInst.h" 25#include "llvm/IR/Module.h" 26#include "llvm/Support/CallSite.h" 27#include "llvm/Support/CommandLine.h" 28#include "llvm/Support/Debug.h" 29#include "llvm/Support/raw_ostream.h" 30#include "llvm/Target/TargetLibraryInfo.h" 31#include "llvm/Transforms/Utils/Cloning.h" 32#include "llvm/Transforms/Utils/Local.h" 33using namespace llvm; 34 35STATISTIC(NumInlined, "Number of functions inlined"); 36STATISTIC(NumCallsDeleted, "Number of call sites deleted, not inlined"); 37STATISTIC(NumDeleted, "Number of functions deleted because all callers found"); 38STATISTIC(NumMergedAllocas, "Number of allocas merged together"); 39 40// This weirdly named statistic tracks the number of times that, when attempting 41// to inline a function A into B, we analyze the callers of B in order to see 42// if those would be more profitable and blocked inline steps. 43STATISTIC(NumCallerCallersAnalyzed, "Number of caller-callers analyzed"); 44 45static cl::opt<int> 46InlineLimit("inline-threshold", cl::Hidden, cl::init(225), cl::ZeroOrMore, 47 cl::desc("Control the amount of inlining to perform (default = 225)")); 48 49static cl::opt<int> 50HintThreshold("inlinehint-threshold", cl::Hidden, cl::init(325), 51 cl::desc("Threshold for inlining functions with inline hint")); 52 53// Threshold to use when optsize is specified (and there is no -inline-limit). 54const int OptSizeThreshold = 75; 55 56Inliner::Inliner(char &ID) 57 : CallGraphSCCPass(ID), InlineThreshold(InlineLimit), InsertLifetime(true) {} 58 59Inliner::Inliner(char &ID, int Threshold, bool InsertLifetime) 60 : CallGraphSCCPass(ID), InlineThreshold(InlineLimit.getNumOccurrences() > 0 ? 61 InlineLimit : Threshold), 62 InsertLifetime(InsertLifetime) {} 63 64/// getAnalysisUsage - For this class, we declare that we require and preserve 65/// the call graph. If the derived class implements this method, it should 66/// always explicitly call the implementation here. 67void Inliner::getAnalysisUsage(AnalysisUsage &AU) const { 68 CallGraphSCCPass::getAnalysisUsage(AU); 69} 70 71 72typedef DenseMap<ArrayType*, std::vector<AllocaInst*> > 73InlinedArrayAllocasTy; 74 75/// \brief If the inlined function had a higher stack protection level than the 76/// calling function, then bump up the caller's stack protection level. 77static void AdjustCallerSSPLevel(Function *Caller, Function *Callee) { 78 // If upgrading the SSP attribute, clear out the old SSP Attributes first. 79 // Having multiple SSP attributes doesn't actually hurt, but it adds useless 80 // clutter to the IR. 81 AttrBuilder B; 82 B.addAttribute(Attribute::StackProtect) 83 .addAttribute(Attribute::StackProtectStrong); 84 AttributeSet OldSSPAttr = AttributeSet::get(Caller->getContext(), 85 AttributeSet::FunctionIndex, 86 B); 87 AttributeSet CallerAttr = Caller->getAttributes(), 88 CalleeAttr = Callee->getAttributes(); 89 90 if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex, 91 Attribute::StackProtectReq)) { 92 Caller->removeAttributes(AttributeSet::FunctionIndex, OldSSPAttr); 93 Caller->addFnAttr(Attribute::StackProtectReq); 94 } else if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex, 95 Attribute::StackProtectStrong) && 96 !CallerAttr.hasAttribute(AttributeSet::FunctionIndex, 97 Attribute::StackProtectReq)) { 98 Caller->removeAttributes(AttributeSet::FunctionIndex, OldSSPAttr); 99 Caller->addFnAttr(Attribute::StackProtectStrong); 100 } else if (CalleeAttr.hasAttribute(AttributeSet::FunctionIndex, 101 Attribute::StackProtect) && 102 !CallerAttr.hasAttribute(AttributeSet::FunctionIndex, 103 Attribute::StackProtectReq) && 104 !CallerAttr.hasAttribute(AttributeSet::FunctionIndex, 105 Attribute::StackProtectStrong)) 106 Caller->addFnAttr(Attribute::StackProtect); 107} 108 109/// InlineCallIfPossible - If it is possible to inline the specified call site, 110/// do so and update the CallGraph for this operation. 111/// 112/// This function also does some basic book-keeping to update the IR. The 113/// InlinedArrayAllocas map keeps track of any allocas that are already 114/// available from other functions inlined into the caller. If we are able to 115/// inline this call site we attempt to reuse already available allocas or add 116/// any new allocas to the set if not possible. 117static bool InlineCallIfPossible(CallSite CS, InlineFunctionInfo &IFI, 118 InlinedArrayAllocasTy &InlinedArrayAllocas, 119 int InlineHistory, bool InsertLifetime) { 120 Function *Callee = CS.getCalledFunction(); 121 Function *Caller = CS.getCaller(); 122 123 // Try to inline the function. Get the list of static allocas that were 124 // inlined. 125 if (!InlineFunction(CS, IFI, InsertLifetime)) 126 return false; 127 128 AdjustCallerSSPLevel(Caller, Callee); 129 130 // Look at all of the allocas that we inlined through this call site. If we 131 // have already inlined other allocas through other calls into this function, 132 // then we know that they have disjoint lifetimes and that we can merge them. 133 // 134 // There are many heuristics possible for merging these allocas, and the 135 // different options have different tradeoffs. One thing that we *really* 136 // don't want to hurt is SRoA: once inlining happens, often allocas are no 137 // longer address taken and so they can be promoted. 138 // 139 // Our "solution" for that is to only merge allocas whose outermost type is an 140 // array type. These are usually not promoted because someone is using a 141 // variable index into them. These are also often the most important ones to 142 // merge. 143 // 144 // A better solution would be to have real memory lifetime markers in the IR 145 // and not have the inliner do any merging of allocas at all. This would 146 // allow the backend to do proper stack slot coloring of all allocas that 147 // *actually make it to the backend*, which is really what we want. 148 // 149 // Because we don't have this information, we do this simple and useful hack. 150 // 151 SmallPtrSet<AllocaInst*, 16> UsedAllocas; 152 153 // When processing our SCC, check to see if CS was inlined from some other 154 // call site. For example, if we're processing "A" in this code: 155 // A() { B() } 156 // B() { x = alloca ... C() } 157 // C() { y = alloca ... } 158 // Assume that C was not inlined into B initially, and so we're processing A 159 // and decide to inline B into A. Doing this makes an alloca available for 160 // reuse and makes a callsite (C) available for inlining. When we process 161 // the C call site we don't want to do any alloca merging between X and Y 162 // because their scopes are not disjoint. We could make this smarter by 163 // keeping track of the inline history for each alloca in the 164 // InlinedArrayAllocas but this isn't likely to be a significant win. 165 if (InlineHistory != -1) // Only do merging for top-level call sites in SCC. 166 return true; 167 168 // Loop over all the allocas we have so far and see if they can be merged with 169 // a previously inlined alloca. If not, remember that we had it. 170 for (unsigned AllocaNo = 0, e = IFI.StaticAllocas.size(); 171 AllocaNo != e; ++AllocaNo) { 172 AllocaInst *AI = IFI.StaticAllocas[AllocaNo]; 173 174 // Don't bother trying to merge array allocations (they will usually be 175 // canonicalized to be an allocation *of* an array), or allocations whose 176 // type is not itself an array (because we're afraid of pessimizing SRoA). 177 ArrayType *ATy = dyn_cast<ArrayType>(AI->getAllocatedType()); 178 if (ATy == 0 || AI->isArrayAllocation()) 179 continue; 180 181 // Get the list of all available allocas for this array type. 182 std::vector<AllocaInst*> &AllocasForType = InlinedArrayAllocas[ATy]; 183 184 // Loop over the allocas in AllocasForType to see if we can reuse one. Note 185 // that we have to be careful not to reuse the same "available" alloca for 186 // multiple different allocas that we just inlined, we use the 'UsedAllocas' 187 // set to keep track of which "available" allocas are being used by this 188 // function. Also, AllocasForType can be empty of course! 189 bool MergedAwayAlloca = false; 190 for (unsigned i = 0, e = AllocasForType.size(); i != e; ++i) { 191 AllocaInst *AvailableAlloca = AllocasForType[i]; 192 193 // The available alloca has to be in the right function, not in some other 194 // function in this SCC. 195 if (AvailableAlloca->getParent() != AI->getParent()) 196 continue; 197 198 // If the inlined function already uses this alloca then we can't reuse 199 // it. 200 if (!UsedAllocas.insert(AvailableAlloca)) 201 continue; 202 203 // Otherwise, we *can* reuse it, RAUW AI into AvailableAlloca and declare 204 // success! 205 DEBUG(dbgs() << " ***MERGED ALLOCA: " << *AI << "\n\t\tINTO: " 206 << *AvailableAlloca << '\n'); 207 208 AI->replaceAllUsesWith(AvailableAlloca); 209 AI->eraseFromParent(); 210 MergedAwayAlloca = true; 211 ++NumMergedAllocas; 212 IFI.StaticAllocas[AllocaNo] = 0; 213 break; 214 } 215 216 // If we already nuked the alloca, we're done with it. 217 if (MergedAwayAlloca) 218 continue; 219 220 // If we were unable to merge away the alloca either because there are no 221 // allocas of the right type available or because we reused them all 222 // already, remember that this alloca came from an inlined function and mark 223 // it used so we don't reuse it for other allocas from this inline 224 // operation. 225 AllocasForType.push_back(AI); 226 UsedAllocas.insert(AI); 227 } 228 229 return true; 230} 231 232unsigned Inliner::getInlineThreshold(CallSite CS) const { 233 int thres = InlineThreshold; // -inline-threshold or else selected by 234 // overall opt level 235 236 // If -inline-threshold is not given, listen to the optsize attribute when it 237 // would decrease the threshold. 238 Function *Caller = CS.getCaller(); 239 bool OptSize = Caller && !Caller->isDeclaration() && 240 Caller->getAttributes().hasAttribute(AttributeSet::FunctionIndex, 241 Attribute::OptimizeForSize); 242 if (!(InlineLimit.getNumOccurrences() > 0) && OptSize && 243 OptSizeThreshold < thres) 244 thres = OptSizeThreshold; 245 246 // Listen to the inlinehint attribute when it would increase the threshold 247 // and the caller does not need to minimize its size. 248 Function *Callee = CS.getCalledFunction(); 249 bool InlineHint = Callee && !Callee->isDeclaration() && 250 Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex, 251 Attribute::InlineHint); 252 if (InlineHint && HintThreshold > thres 253 && !Caller->getAttributes().hasAttribute(AttributeSet::FunctionIndex, 254 Attribute::MinSize)) 255 thres = HintThreshold; 256 257 return thres; 258} 259 260/// shouldInline - Return true if the inliner should attempt to inline 261/// at the given CallSite. 262bool Inliner::shouldInline(CallSite CS) { 263 InlineCost IC = getInlineCost(CS); 264 265 if (IC.isAlways()) { 266 DEBUG(dbgs() << " Inlining: cost=always" 267 << ", Call: " << *CS.getInstruction() << "\n"); 268 return true; 269 } 270 271 if (IC.isNever()) { 272 DEBUG(dbgs() << " NOT Inlining: cost=never" 273 << ", Call: " << *CS.getInstruction() << "\n"); 274 return false; 275 } 276 277 Function *Caller = CS.getCaller(); 278 if (!IC) { 279 DEBUG(dbgs() << " NOT Inlining: cost=" << IC.getCost() 280 << ", thres=" << (IC.getCostDelta() + IC.getCost()) 281 << ", Call: " << *CS.getInstruction() << "\n"); 282 return false; 283 } 284 285 // Try to detect the case where the current inlining candidate caller (call 286 // it B) is a static or linkonce-ODR function and is an inlining candidate 287 // elsewhere, and the current candidate callee (call it C) is large enough 288 // that inlining it into B would make B too big to inline later. In these 289 // circumstances it may be best not to inline C into B, but to inline B into 290 // its callers. 291 // 292 // This only applies to static and linkonce-ODR functions because those are 293 // expected to be available for inlining in the translation units where they 294 // are used. Thus we will always have the opportunity to make local inlining 295 // decisions. Importantly the linkonce-ODR linkage covers inline functions 296 // and templates in C++. 297 // 298 // FIXME: All of this logic should be sunk into getInlineCost. It relies on 299 // the internal implementation of the inline cost metrics rather than 300 // treating them as truly abstract units etc. 301 if (Caller->hasLocalLinkage() || 302 Caller->getLinkage() == GlobalValue::LinkOnceODRLinkage) { 303 int TotalSecondaryCost = 0; 304 // The candidate cost to be imposed upon the current function. 305 int CandidateCost = IC.getCost() - (InlineConstants::CallPenalty + 1); 306 // This bool tracks what happens if we do NOT inline C into B. 307 bool callerWillBeRemoved = Caller->hasLocalLinkage(); 308 // This bool tracks what happens if we DO inline C into B. 309 bool inliningPreventsSomeOuterInline = false; 310 for (Value::use_iterator I = Caller->use_begin(), E =Caller->use_end(); 311 I != E; ++I) { 312 CallSite CS2(*I); 313 314 // If this isn't a call to Caller (it could be some other sort 315 // of reference) skip it. Such references will prevent the caller 316 // from being removed. 317 if (!CS2 || CS2.getCalledFunction() != Caller) { 318 callerWillBeRemoved = false; 319 continue; 320 } 321 322 InlineCost IC2 = getInlineCost(CS2); 323 ++NumCallerCallersAnalyzed; 324 if (!IC2) { 325 callerWillBeRemoved = false; 326 continue; 327 } 328 if (IC2.isAlways()) 329 continue; 330 331 // See if inlining or original callsite would erase the cost delta of 332 // this callsite. We subtract off the penalty for the call instruction, 333 // which we would be deleting. 334 if (IC2.getCostDelta() <= CandidateCost) { 335 inliningPreventsSomeOuterInline = true; 336 TotalSecondaryCost += IC2.getCost(); 337 } 338 } 339 // If all outer calls to Caller would get inlined, the cost for the last 340 // one is set very low by getInlineCost, in anticipation that Caller will 341 // be removed entirely. We did not account for this above unless there 342 // is only one caller of Caller. 343 if (callerWillBeRemoved && Caller->use_begin() != Caller->use_end()) 344 TotalSecondaryCost += InlineConstants::LastCallToStaticBonus; 345 346 if (inliningPreventsSomeOuterInline && TotalSecondaryCost < IC.getCost()) { 347 DEBUG(dbgs() << " NOT Inlining: " << *CS.getInstruction() << 348 " Cost = " << IC.getCost() << 349 ", outer Cost = " << TotalSecondaryCost << '\n'); 350 return false; 351 } 352 } 353 354 DEBUG(dbgs() << " Inlining: cost=" << IC.getCost() 355 << ", thres=" << (IC.getCostDelta() + IC.getCost()) 356 << ", Call: " << *CS.getInstruction() << '\n'); 357 return true; 358} 359 360/// InlineHistoryIncludes - Return true if the specified inline history ID 361/// indicates an inline history that includes the specified function. 362static bool InlineHistoryIncludes(Function *F, int InlineHistoryID, 363 const SmallVectorImpl<std::pair<Function*, int> > &InlineHistory) { 364 while (InlineHistoryID != -1) { 365 assert(unsigned(InlineHistoryID) < InlineHistory.size() && 366 "Invalid inline history ID"); 367 if (InlineHistory[InlineHistoryID].first == F) 368 return true; 369 InlineHistoryID = InlineHistory[InlineHistoryID].second; 370 } 371 return false; 372} 373 374bool Inliner::runOnSCC(CallGraphSCC &SCC) { 375 CallGraph &CG = getAnalysis<CallGraph>(); 376 const DataLayout *TD = getAnalysisIfAvailable<DataLayout>(); 377 const TargetLibraryInfo *TLI = getAnalysisIfAvailable<TargetLibraryInfo>(); 378 379 SmallPtrSet<Function*, 8> SCCFunctions; 380 DEBUG(dbgs() << "Inliner visiting SCC:"); 381 for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { 382 Function *F = (*I)->getFunction(); 383 if (F) SCCFunctions.insert(F); 384 DEBUG(dbgs() << " " << (F ? F->getName() : "INDIRECTNODE")); 385 } 386 387 // Scan through and identify all call sites ahead of time so that we only 388 // inline call sites in the original functions, not call sites that result 389 // from inlining other functions. 390 SmallVector<std::pair<CallSite, int>, 16> CallSites; 391 392 // When inlining a callee produces new call sites, we want to keep track of 393 // the fact that they were inlined from the callee. This allows us to avoid 394 // infinite inlining in some obscure cases. To represent this, we use an 395 // index into the InlineHistory vector. 396 SmallVector<std::pair<Function*, int>, 8> InlineHistory; 397 398 for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) { 399 Function *F = (*I)->getFunction(); 400 if (!F) continue; 401 402 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) 403 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { 404 CallSite CS(cast<Value>(I)); 405 // If this isn't a call, or it is a call to an intrinsic, it can 406 // never be inlined. 407 if (!CS || isa<IntrinsicInst>(I)) 408 continue; 409 410 // If this is a direct call to an external function, we can never inline 411 // it. If it is an indirect call, inlining may resolve it to be a 412 // direct call, so we keep it. 413 if (CS.getCalledFunction() && CS.getCalledFunction()->isDeclaration()) 414 continue; 415 416 CallSites.push_back(std::make_pair(CS, -1)); 417 } 418 } 419 420 DEBUG(dbgs() << ": " << CallSites.size() << " call sites.\n"); 421 422 // If there are no calls in this function, exit early. 423 if (CallSites.empty()) 424 return false; 425 426 // Now that we have all of the call sites, move the ones to functions in the 427 // current SCC to the end of the list. 428 unsigned FirstCallInSCC = CallSites.size(); 429 for (unsigned i = 0; i < FirstCallInSCC; ++i) 430 if (Function *F = CallSites[i].first.getCalledFunction()) 431 if (SCCFunctions.count(F)) 432 std::swap(CallSites[i--], CallSites[--FirstCallInSCC]); 433 434 435 InlinedArrayAllocasTy InlinedArrayAllocas; 436 InlineFunctionInfo InlineInfo(&CG, TD); 437 438 // Now that we have all of the call sites, loop over them and inline them if 439 // it looks profitable to do so. 440 bool Changed = false; 441 bool LocalChange; 442 do { 443 LocalChange = false; 444 // Iterate over the outer loop because inlining functions can cause indirect 445 // calls to become direct calls. 446 for (unsigned CSi = 0; CSi != CallSites.size(); ++CSi) { 447 CallSite CS = CallSites[CSi].first; 448 449 Function *Caller = CS.getCaller(); 450 Function *Callee = CS.getCalledFunction(); 451 452 // If this call site is dead and it is to a readonly function, we should 453 // just delete the call instead of trying to inline it, regardless of 454 // size. This happens because IPSCCP propagates the result out of the 455 // call and then we're left with the dead call. 456 if (isInstructionTriviallyDead(CS.getInstruction(), TLI)) { 457 DEBUG(dbgs() << " -> Deleting dead call: " 458 << *CS.getInstruction() << "\n"); 459 // Update the call graph by deleting the edge from Callee to Caller. 460 CG[Caller]->removeCallEdgeFor(CS); 461 CS.getInstruction()->eraseFromParent(); 462 ++NumCallsDeleted; 463 } else { 464 // We can only inline direct calls to non-declarations. 465 if (Callee == 0 || Callee->isDeclaration()) continue; 466 467 // If this call site was obtained by inlining another function, verify 468 // that the include path for the function did not include the callee 469 // itself. If so, we'd be recursively inlining the same function, 470 // which would provide the same callsites, which would cause us to 471 // infinitely inline. 472 int InlineHistoryID = CallSites[CSi].second; 473 if (InlineHistoryID != -1 && 474 InlineHistoryIncludes(Callee, InlineHistoryID, InlineHistory)) 475 continue; 476 477 478 // If the policy determines that we should inline this function, 479 // try to do so. 480 if (!shouldInline(CS)) 481 continue; 482 483 // Attempt to inline the function. 484 if (!InlineCallIfPossible(CS, InlineInfo, InlinedArrayAllocas, 485 InlineHistoryID, InsertLifetime)) 486 continue; 487 ++NumInlined; 488 489 // If inlining this function gave us any new call sites, throw them 490 // onto our worklist to process. They are useful inline candidates. 491 if (!InlineInfo.InlinedCalls.empty()) { 492 // Create a new inline history entry for this, so that we remember 493 // that these new callsites came about due to inlining Callee. 494 int NewHistoryID = InlineHistory.size(); 495 InlineHistory.push_back(std::make_pair(Callee, InlineHistoryID)); 496 497 for (unsigned i = 0, e = InlineInfo.InlinedCalls.size(); 498 i != e; ++i) { 499 Value *Ptr = InlineInfo.InlinedCalls[i]; 500 CallSites.push_back(std::make_pair(CallSite(Ptr), NewHistoryID)); 501 } 502 } 503 } 504 505 // If we inlined or deleted the last possible call site to the function, 506 // delete the function body now. 507 if (Callee && Callee->use_empty() && Callee->hasLocalLinkage() && 508 // TODO: Can remove if in SCC now. 509 !SCCFunctions.count(Callee) && 510 511 // The function may be apparently dead, but if there are indirect 512 // callgraph references to the node, we cannot delete it yet, this 513 // could invalidate the CGSCC iterator. 514 CG[Callee]->getNumReferences() == 0) { 515 DEBUG(dbgs() << " -> Deleting dead function: " 516 << Callee->getName() << "\n"); 517 CallGraphNode *CalleeNode = CG[Callee]; 518 519 // Remove any call graph edges from the callee to its callees. 520 CalleeNode->removeAllCalledFunctions(); 521 522 // Removing the node for callee from the call graph and delete it. 523 delete CG.removeFunctionFromModule(CalleeNode); 524 ++NumDeleted; 525 } 526 527 // Remove this call site from the list. If possible, use 528 // swap/pop_back for efficiency, but do not use it if doing so would 529 // move a call site to a function in this SCC before the 530 // 'FirstCallInSCC' barrier. 531 if (SCC.isSingular()) { 532 CallSites[CSi] = CallSites.back(); 533 CallSites.pop_back(); 534 } else { 535 CallSites.erase(CallSites.begin()+CSi); 536 } 537 --CSi; 538 539 Changed = true; 540 LocalChange = true; 541 } 542 } while (LocalChange); 543 544 return Changed; 545} 546 547// doFinalization - Remove now-dead linkonce functions at the end of 548// processing to avoid breaking the SCC traversal. 549bool Inliner::doFinalization(CallGraph &CG) { 550 return removeDeadFunctions(CG); 551} 552 553/// removeDeadFunctions - Remove dead functions that are not included in 554/// DNR (Do Not Remove) list. 555bool Inliner::removeDeadFunctions(CallGraph &CG, bool AlwaysInlineOnly) { 556 SmallVector<CallGraphNode*, 16> FunctionsToRemove; 557 558 // Scan for all of the functions, looking for ones that should now be removed 559 // from the program. Insert the dead ones in the FunctionsToRemove set. 560 for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) { 561 CallGraphNode *CGN = I->second; 562 Function *F = CGN->getFunction(); 563 if (!F || F->isDeclaration()) 564 continue; 565 566 // Handle the case when this function is called and we only want to care 567 // about always-inline functions. This is a bit of a hack to share code 568 // between here and the InlineAlways pass. 569 if (AlwaysInlineOnly && 570 !F->getAttributes().hasAttribute(AttributeSet::FunctionIndex, 571 Attribute::AlwaysInline)) 572 continue; 573 574 // If the only remaining users of the function are dead constants, remove 575 // them. 576 F->removeDeadConstantUsers(); 577 578 if (!F->isDefTriviallyDead()) 579 continue; 580 581 // Remove any call graph edges from the function to its callees. 582 CGN->removeAllCalledFunctions(); 583 584 // Remove any edges from the external node to the function's call graph 585 // node. These edges might have been made irrelegant due to 586 // optimization of the program. 587 CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN); 588 589 // Removing the node for callee from the call graph and delete it. 590 FunctionsToRemove.push_back(CGN); 591 } 592 if (FunctionsToRemove.empty()) 593 return false; 594 595 // Now that we know which functions to delete, do so. We didn't want to do 596 // this inline, because that would invalidate our CallGraph::iterator 597 // objects. :( 598 // 599 // Note that it doesn't matter that we are iterating over a non-stable order 600 // here to do this, it doesn't matter which order the functions are deleted 601 // in. 602 array_pod_sort(FunctionsToRemove.begin(), FunctionsToRemove.end()); 603 FunctionsToRemove.erase(std::unique(FunctionsToRemove.begin(), 604 FunctionsToRemove.end()), 605 FunctionsToRemove.end()); 606 for (SmallVectorImpl<CallGraphNode *>::iterator I = FunctionsToRemove.begin(), 607 E = FunctionsToRemove.end(); 608 I != E; ++I) { 609 delete CG.removeFunctionFromModule(*I); 610 ++NumDeleted; 611 } 612 return true; 613} 614