InlineFunction.cpp revision fd3adbb31a2745e18d8964d3db02d4d5879202af
1//===- InlineFunction.cpp - Code to perform function inlining -------------===// 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 inlining of a function into a call site, resolving 11// parameters and the return value as appropriate. 12// 13// The code in this file for handling inlines through invoke 14// instructions preserves semantics only under some assumptions about 15// the behavior of unwinders which correspond to gcc-style libUnwind 16// exception personality functions. Eventually the IR will be 17// improved to make this unnecessary, but until then, this code is 18// marked [LIBUNWIND]. 19// 20//===----------------------------------------------------------------------===// 21 22#include "llvm/Transforms/Utils/Cloning.h" 23#include "llvm/Constants.h" 24#include "llvm/DerivedTypes.h" 25#include "llvm/Module.h" 26#include "llvm/Instructions.h" 27#include "llvm/IntrinsicInst.h" 28#include "llvm/Intrinsics.h" 29#include "llvm/Attributes.h" 30#include "llvm/Analysis/CallGraph.h" 31#include "llvm/Analysis/DebugInfo.h" 32#include "llvm/Analysis/InstructionSimplify.h" 33#include "llvm/Target/TargetData.h" 34#include "llvm/Transforms/Utils/Local.h" 35#include "llvm/ADT/SmallVector.h" 36#include "llvm/ADT/StringExtras.h" 37#include "llvm/Support/CallSite.h" 38#include "llvm/Support/IRBuilder.h" 39using namespace llvm; 40 41bool llvm::InlineFunction(CallInst *CI, InlineFunctionInfo &IFI) { 42 return InlineFunction(CallSite(CI), IFI); 43} 44bool llvm::InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI) { 45 return InlineFunction(CallSite(II), IFI); 46} 47 48// FIXME: New EH - Remove the functions marked [LIBUNWIND] when new EH is 49// turned on. 50 51/// [LIBUNWIND] Look for an llvm.eh.exception call in the given block. 52static EHExceptionInst *findExceptionInBlock(BasicBlock *bb) { 53 for (BasicBlock::iterator i = bb->begin(), e = bb->end(); i != e; i++) { 54 EHExceptionInst *exn = dyn_cast<EHExceptionInst>(i); 55 if (exn) return exn; 56 } 57 58 return 0; 59} 60 61/// [LIBUNWIND] Look for the 'best' llvm.eh.selector instruction for 62/// the given llvm.eh.exception call. 63static EHSelectorInst *findSelectorForException(EHExceptionInst *exn) { 64 BasicBlock *exnBlock = exn->getParent(); 65 66 EHSelectorInst *outOfBlockSelector = 0; 67 for (Instruction::use_iterator 68 ui = exn->use_begin(), ue = exn->use_end(); ui != ue; ++ui) { 69 EHSelectorInst *sel = dyn_cast<EHSelectorInst>(*ui); 70 if (!sel) continue; 71 72 // Immediately accept an eh.selector in the same block as the 73 // excepton call. 74 if (sel->getParent() == exnBlock) return sel; 75 76 // Otherwise, use the first selector we see. 77 if (!outOfBlockSelector) outOfBlockSelector = sel; 78 } 79 80 return outOfBlockSelector; 81} 82 83/// [LIBUNWIND] Find the (possibly absent) call to @llvm.eh.selector 84/// in the given landing pad. In principle, llvm.eh.exception is 85/// required to be in the landing pad; in practice, SplitCriticalEdge 86/// can break that invariant, and then inlining can break it further. 87/// There's a real need for a reliable solution here, but until that 88/// happens, we have some fragile workarounds here. 89static EHSelectorInst *findSelectorForLandingPad(BasicBlock *lpad) { 90 // Look for an exception call in the actual landing pad. 91 EHExceptionInst *exn = findExceptionInBlock(lpad); 92 if (exn) return findSelectorForException(exn); 93 94 // Okay, if that failed, look for one in an obvious successor. If 95 // we find one, we'll fix the IR by moving things back to the 96 // landing pad. 97 98 bool dominates = true; // does the lpad dominate the exn call 99 BasicBlock *nonDominated = 0; // if not, the first non-dominated block 100 BasicBlock *lastDominated = 0; // and the block which branched to it 101 102 BasicBlock *exnBlock = lpad; 103 104 // We need to protect against lpads that lead into infinite loops. 105 SmallPtrSet<BasicBlock*,4> visited; 106 visited.insert(exnBlock); 107 108 do { 109 // We're not going to apply this hack to anything more complicated 110 // than a series of unconditional branches, so if the block 111 // doesn't terminate in an unconditional branch, just fail. More 112 // complicated cases can arise when, say, sinking a call into a 113 // split unwind edge and then inlining it; but that can do almost 114 // *anything* to the CFG, including leaving the selector 115 // completely unreachable. The only way to fix that properly is 116 // to (1) prohibit transforms which move the exception or selector 117 // values away from the landing pad, e.g. by producing them with 118 // instructions that are pinned to an edge like a phi, or 119 // producing them with not-really-instructions, and (2) making 120 // transforms which split edges deal with that. 121 BranchInst *branch = dyn_cast<BranchInst>(&exnBlock->back()); 122 if (!branch || branch->isConditional()) return 0; 123 124 BasicBlock *successor = branch->getSuccessor(0); 125 126 // Fail if we found an infinite loop. 127 if (!visited.insert(successor)) return 0; 128 129 // If the successor isn't dominated by exnBlock: 130 if (!successor->getSinglePredecessor()) { 131 // We don't want to have to deal with threading the exception 132 // through multiple levels of phi, so give up if we've already 133 // followed a non-dominating edge. 134 if (!dominates) return 0; 135 136 // Otherwise, remember this as a non-dominating edge. 137 dominates = false; 138 nonDominated = successor; 139 lastDominated = exnBlock; 140 } 141 142 exnBlock = successor; 143 144 // Can we stop here? 145 exn = findExceptionInBlock(exnBlock); 146 } while (!exn); 147 148 // Look for a selector call for the exception we found. 149 EHSelectorInst *selector = findSelectorForException(exn); 150 if (!selector) return 0; 151 152 // The easy case is when the landing pad still dominates the 153 // exception call, in which case we can just move both calls back to 154 // the landing pad. 155 if (dominates) { 156 selector->moveBefore(lpad->getFirstNonPHI()); 157 exn->moveBefore(selector); 158 return selector; 159 } 160 161 // Otherwise, we have to split at the first non-dominating block. 162 // The CFG looks basically like this: 163 // lpad: 164 // phis_0 165 // insnsAndBranches_1 166 // br label %nonDominated 167 // nonDominated: 168 // phis_2 169 // insns_3 170 // %exn = call i8* @llvm.eh.exception() 171 // insnsAndBranches_4 172 // %selector = call @llvm.eh.selector(i8* %exn, ... 173 // We need to turn this into: 174 // lpad: 175 // phis_0 176 // %exn0 = call i8* @llvm.eh.exception() 177 // %selector0 = call @llvm.eh.selector(i8* %exn0, ... 178 // insnsAndBranches_1 179 // br label %split // from lastDominated 180 // nonDominated: 181 // phis_2 (without edge from lastDominated) 182 // %exn1 = call i8* @llvm.eh.exception() 183 // %selector1 = call i8* @llvm.eh.selector(i8* %exn1, ... 184 // br label %split 185 // split: 186 // phis_2 (edge from lastDominated, edge from split) 187 // %exn = phi ... 188 // %selector = phi ... 189 // insns_3 190 // insnsAndBranches_4 191 192 assert(nonDominated); 193 assert(lastDominated); 194 195 // First, make clones of the intrinsics to go in lpad. 196 EHExceptionInst *lpadExn = cast<EHExceptionInst>(exn->clone()); 197 EHSelectorInst *lpadSelector = cast<EHSelectorInst>(selector->clone()); 198 lpadSelector->setArgOperand(0, lpadExn); 199 lpadSelector->insertBefore(lpad->getFirstNonPHI()); 200 lpadExn->insertBefore(lpadSelector); 201 202 // Split the non-dominated block. 203 BasicBlock *split = 204 nonDominated->splitBasicBlock(nonDominated->getFirstNonPHI(), 205 nonDominated->getName() + ".lpad-fix"); 206 207 // Redirect the last dominated branch there. 208 cast<BranchInst>(lastDominated->back()).setSuccessor(0, split); 209 210 // Move the existing intrinsics to the end of the old block. 211 selector->moveBefore(&nonDominated->back()); 212 exn->moveBefore(selector); 213 214 Instruction *splitIP = &split->front(); 215 216 // For all the phis in nonDominated, make a new phi in split to join 217 // that phi with the edge from lastDominated. 218 for (BasicBlock::iterator 219 i = nonDominated->begin(), e = nonDominated->end(); i != e; ++i) { 220 PHINode *phi = dyn_cast<PHINode>(i); 221 if (!phi) break; 222 223 PHINode *splitPhi = PHINode::Create(phi->getType(), 2, phi->getName(), 224 splitIP); 225 phi->replaceAllUsesWith(splitPhi); 226 splitPhi->addIncoming(phi, nonDominated); 227 splitPhi->addIncoming(phi->removeIncomingValue(lastDominated), 228 lastDominated); 229 } 230 231 // Make new phis for the exception and selector. 232 PHINode *exnPhi = PHINode::Create(exn->getType(), 2, "", splitIP); 233 exn->replaceAllUsesWith(exnPhi); 234 selector->setArgOperand(0, exn); // except for this use 235 exnPhi->addIncoming(exn, nonDominated); 236 exnPhi->addIncoming(lpadExn, lastDominated); 237 238 PHINode *selectorPhi = PHINode::Create(selector->getType(), 2, "", splitIP); 239 selector->replaceAllUsesWith(selectorPhi); 240 selectorPhi->addIncoming(selector, nonDominated); 241 selectorPhi->addIncoming(lpadSelector, lastDominated); 242 243 return lpadSelector; 244} 245 246namespace { 247 /// A class for recording information about inlining through an invoke. 248 class InvokeInliningInfo { 249 BasicBlock *OuterUnwindDest; 250 EHSelectorInst *OuterSelector; 251 BasicBlock *InnerUnwindDest; 252 PHINode *InnerExceptionPHI; 253 PHINode *InnerSelectorPHI; 254 SmallVector<Value*, 8> UnwindDestPHIValues; 255 256 // FIXME: New EH - These will replace the analogous ones above. 257 BasicBlock *OuterResumeDest; //< Destination of the invoke's unwind. 258 BasicBlock *InnerResumeDest; //< Destination for the callee's resume. 259 LandingPadInst *CallerLPad; //< LandingPadInst associated with the invoke. 260 PHINode *InnerEHValuesPHI; //< PHI for EH values from landingpad insts. 261 262 public: 263 InvokeInliningInfo(InvokeInst *II) 264 : OuterUnwindDest(II->getUnwindDest()), OuterSelector(0), 265 InnerUnwindDest(0), InnerExceptionPHI(0), InnerSelectorPHI(0), 266 OuterResumeDest(II->getUnwindDest()), InnerResumeDest(0), 267 CallerLPad(0), InnerEHValuesPHI(0) { 268 // If there are PHI nodes in the unwind destination block, we need to keep 269 // track of which values came into them from the invoke before removing 270 // the edge from this block. 271 llvm::BasicBlock *InvokeBB = II->getParent(); 272 BasicBlock::iterator I = OuterUnwindDest->begin(); 273 for (; isa<PHINode>(I); ++I) { 274 // Save the value to use for this edge. 275 PHINode *PHI = cast<PHINode>(I); 276 UnwindDestPHIValues.push_back(PHI->getIncomingValueForBlock(InvokeBB)); 277 } 278 279 CallerLPad = cast<LandingPadInst>(I); 280 } 281 282 /// The outer unwind destination is the target of unwind edges 283 /// introduced for calls within the inlined function. 284 BasicBlock *getOuterUnwindDest() const { 285 return OuterUnwindDest; 286 } 287 288 EHSelectorInst *getOuterSelector() { 289 if (!OuterSelector) 290 OuterSelector = findSelectorForLandingPad(OuterUnwindDest); 291 return OuterSelector; 292 } 293 294 BasicBlock *getInnerUnwindDest(); 295 296 LandingPadInst *getLandingPadInst() const { return CallerLPad; } 297 298 /// forwardResume - Forward the 'resume' instruction to the caller's landing 299 /// pad block. When the landing pad block has only one predecessor, this is 300 /// a simple branch. When there is more than one predecessor, we need to 301 /// split the landing pad block after the landingpad instruction and jump 302 /// to there. 303 void forwardResume(ResumeInst *RI); 304 305 /// addIncomingPHIValuesFor - Add incoming-PHI values to the unwind 306 /// destination block for the given basic block, using the values for the 307 /// original invoke's source block. 308 void addIncomingPHIValuesFor(BasicBlock *BB) const { 309 addIncomingPHIValuesForInto(BB, OuterUnwindDest); 310 } 311 312 void addIncomingPHIValuesForInto(BasicBlock *src, BasicBlock *dest) const { 313 BasicBlock::iterator I = dest->begin(); 314 for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) { 315 PHINode *phi = cast<PHINode>(I); 316 phi->addIncoming(UnwindDestPHIValues[i], src); 317 } 318 } 319 }; 320} 321 322/// getInnerUnwindDest - Get or create a target for the branch from ResumeInsts. 323BasicBlock *InvokeInliningInfo::getInnerUnwindDest() { 324 if (InnerResumeDest) return InnerResumeDest; 325 326 // Split the landing pad. 327 BasicBlock::iterator SplitPoint = CallerLPad; ++SplitPoint; 328 InnerResumeDest = 329 OuterResumeDest->splitBasicBlock(SplitPoint, 330 OuterResumeDest->getName() + ".body"); 331 332 // The number of incoming edges we expect to the inner landing pad. 333 const unsigned PHICapacity = 2; 334 335 // Create corresponding new PHIs for all the PHIs in the outer landing pad. 336 BasicBlock::iterator InsertPoint = InnerResumeDest->begin(); 337 BasicBlock::iterator I = OuterResumeDest->begin(); 338 for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) { 339 PHINode *OuterPHI = cast<PHINode>(I); 340 PHINode *InnerPHI = PHINode::Create(OuterPHI->getType(), PHICapacity, 341 OuterPHI->getName() + ".lpad-body", 342 InsertPoint); 343 OuterPHI->replaceAllUsesWith(InnerPHI); 344 InnerPHI->addIncoming(OuterPHI, OuterResumeDest); 345 } 346 347 // Create a PHI for the exception values. 348 InnerEHValuesPHI = PHINode::Create(CallerLPad->getType(), PHICapacity, 349 "eh.lpad-body", InsertPoint); 350 CallerLPad->replaceAllUsesWith(InnerEHValuesPHI); 351 InnerEHValuesPHI->addIncoming(CallerLPad, OuterResumeDest); 352 353 // All done. 354 return InnerResumeDest; 355} 356 357/// forwardResume - Forward the 'resume' instruction to the caller's landing pad 358/// block. When the landing pad block has only one predecessor, this is a simple 359/// branch. When there is more than one predecessor, we need to split the 360/// landing pad block after the landingpad instruction and jump to there. 361void InvokeInliningInfo::forwardResume(ResumeInst *RI) { 362 BasicBlock *Dest = getInnerUnwindDest(); 363 BasicBlock *Src = RI->getParent(); 364 365 BranchInst::Create(Dest, Src); 366 367 // Update the PHIs in the destination. They were inserted in an order which 368 // makes this work. 369 addIncomingPHIValuesForInto(Src, Dest); 370 371 InnerEHValuesPHI->addIncoming(RI->getOperand(0), Src); 372 RI->eraseFromParent(); 373} 374 375/// HandleCallsInBlockInlinedThroughInvoke - When we inline a basic block into 376/// an invoke, we have to turn all of the calls that can throw into 377/// invokes. This function analyze BB to see if there are any calls, and if so, 378/// it rewrites them to be invokes that jump to InvokeDest and fills in the PHI 379/// nodes in that block with the values specified in InvokeDestPHIValues. 380/// 381/// Returns true to indicate that the next block should be skipped. 382static bool HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB, 383 InvokeInliningInfo &Invoke) { 384 LandingPadInst *LPI = Invoke.getLandingPadInst(); 385 386 for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) { 387 Instruction *I = BBI++; 388 389 if (LandingPadInst *L = dyn_cast<LandingPadInst>(I)) { 390 unsigned NumClauses = LPI->getNumClauses(); 391 L->reserveClauses(NumClauses); 392 for (unsigned i = 0; i != NumClauses; ++i) 393 L->addClause(LPI->getClause(i)); 394 } 395 396 // We only need to check for function calls: inlined invoke 397 // instructions require no special handling. 398 CallInst *CI = dyn_cast<CallInst>(I); 399 400 // If this call cannot unwind, don't convert it to an invoke. 401 if (!CI || CI->doesNotThrow()) 402 continue; 403 404 // Convert this function call into an invoke instruction. First, split the 405 // basic block. 406 BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc"); 407 408 // Delete the unconditional branch inserted by splitBasicBlock 409 BB->getInstList().pop_back(); 410 411 // Create the new invoke instruction. 412 ImmutableCallSite CS(CI); 413 SmallVector<Value*, 8> InvokeArgs(CS.arg_begin(), CS.arg_end()); 414 InvokeInst *II = InvokeInst::Create(CI->getCalledValue(), Split, 415 Invoke.getOuterUnwindDest(), 416 InvokeArgs, CI->getName(), BB); 417 II->setCallingConv(CI->getCallingConv()); 418 II->setAttributes(CI->getAttributes()); 419 420 // Make sure that anything using the call now uses the invoke! This also 421 // updates the CallGraph if present, because it uses a WeakVH. 422 CI->replaceAllUsesWith(II); 423 424 // Delete the original call 425 Split->getInstList().pop_front(); 426 427 // Update any PHI nodes in the exceptional block to indicate that there is 428 // now a new entry in them. 429 Invoke.addIncomingPHIValuesFor(BB); 430 return false; 431 } 432 433 return false; 434} 435 436/// HandleInlinedInvoke - If we inlined an invoke site, we need to convert calls 437/// in the body of the inlined function into invokes and turn unwind 438/// instructions into branches to the invoke unwind dest. 439/// 440/// II is the invoke instruction being inlined. FirstNewBlock is the first 441/// block of the inlined code (the last block is the end of the function), 442/// and InlineCodeInfo is information about the code that got inlined. 443static void HandleInlinedInvoke(InvokeInst *II, BasicBlock *FirstNewBlock, 444 ClonedCodeInfo &InlinedCodeInfo) { 445 BasicBlock *InvokeDest = II->getUnwindDest(); 446 447 Function *Caller = FirstNewBlock->getParent(); 448 449 // The inlined code is currently at the end of the function, scan from the 450 // start of the inlined code to its end, checking for stuff we need to 451 // rewrite. If the code doesn't have calls or unwinds, we know there is 452 // nothing to rewrite. 453 if (!InlinedCodeInfo.ContainsCalls && !InlinedCodeInfo.ContainsUnwinds) { 454 // Now that everything is happy, we have one final detail. The PHI nodes in 455 // the exception destination block still have entries due to the original 456 // invoke instruction. Eliminate these entries (which might even delete the 457 // PHI node) now. 458 InvokeDest->removePredecessor(II->getParent()); 459 return; 460 } 461 462 InvokeInliningInfo Invoke(II); 463 464 for (Function::iterator BB = FirstNewBlock, E = Caller->end(); BB != E; ++BB){ 465 if (InlinedCodeInfo.ContainsCalls) 466 if (HandleCallsInBlockInlinedThroughInvoke(BB, Invoke)) { 467 // Honor a request to skip the next block. We don't need to 468 // consider UnwindInsts in this case either. 469 ++BB; 470 continue; 471 } 472 473 if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { 474 // An UnwindInst requires special handling when it gets inlined into an 475 // invoke site. Once this happens, we know that the unwind would cause 476 // a control transfer to the invoke exception destination, so we can 477 // transform it into a direct branch to the exception destination. 478 BranchInst::Create(InvokeDest, UI); 479 480 // Delete the unwind instruction! 481 UI->eraseFromParent(); 482 483 // Update any PHI nodes in the exceptional block to indicate that 484 // there is now a new entry in them. 485 Invoke.addIncomingPHIValuesFor(BB); 486 } 487 488 if (ResumeInst *RI = dyn_cast<ResumeInst>(BB->getTerminator())) 489 Invoke.forwardResume(RI); 490 } 491 492 // Now that everything is happy, we have one final detail. The PHI nodes in 493 // the exception destination block still have entries due to the original 494 // invoke instruction. Eliminate these entries (which might even delete the 495 // PHI node) now. 496 InvokeDest->removePredecessor(II->getParent()); 497} 498 499/// UpdateCallGraphAfterInlining - Once we have cloned code over from a callee 500/// into the caller, update the specified callgraph to reflect the changes we 501/// made. Note that it's possible that not all code was copied over, so only 502/// some edges of the callgraph may remain. 503static void UpdateCallGraphAfterInlining(CallSite CS, 504 Function::iterator FirstNewBlock, 505 ValueToValueMapTy &VMap, 506 InlineFunctionInfo &IFI) { 507 CallGraph &CG = *IFI.CG; 508 const Function *Caller = CS.getInstruction()->getParent()->getParent(); 509 const Function *Callee = CS.getCalledFunction(); 510 CallGraphNode *CalleeNode = CG[Callee]; 511 CallGraphNode *CallerNode = CG[Caller]; 512 513 // Since we inlined some uninlined call sites in the callee into the caller, 514 // add edges from the caller to all of the callees of the callee. 515 CallGraphNode::iterator I = CalleeNode->begin(), E = CalleeNode->end(); 516 517 // Consider the case where CalleeNode == CallerNode. 518 CallGraphNode::CalledFunctionsVector CallCache; 519 if (CalleeNode == CallerNode) { 520 CallCache.assign(I, E); 521 I = CallCache.begin(); 522 E = CallCache.end(); 523 } 524 525 for (; I != E; ++I) { 526 const Value *OrigCall = I->first; 527 528 ValueToValueMapTy::iterator VMI = VMap.find(OrigCall); 529 // Only copy the edge if the call was inlined! 530 if (VMI == VMap.end() || VMI->second == 0) 531 continue; 532 533 // If the call was inlined, but then constant folded, there is no edge to 534 // add. Check for this case. 535 Instruction *NewCall = dyn_cast<Instruction>(VMI->second); 536 if (NewCall == 0) continue; 537 538 // Remember that this call site got inlined for the client of 539 // InlineFunction. 540 IFI.InlinedCalls.push_back(NewCall); 541 542 // It's possible that inlining the callsite will cause it to go from an 543 // indirect to a direct call by resolving a function pointer. If this 544 // happens, set the callee of the new call site to a more precise 545 // destination. This can also happen if the call graph node of the caller 546 // was just unnecessarily imprecise. 547 if (I->second->getFunction() == 0) 548 if (Function *F = CallSite(NewCall).getCalledFunction()) { 549 // Indirect call site resolved to direct call. 550 CallerNode->addCalledFunction(CallSite(NewCall), CG[F]); 551 552 continue; 553 } 554 555 CallerNode->addCalledFunction(CallSite(NewCall), I->second); 556 } 557 558 // Update the call graph by deleting the edge from Callee to Caller. We must 559 // do this after the loop above in case Caller and Callee are the same. 560 CallerNode->removeCallEdgeFor(CS); 561} 562 563/// HandleByValArgument - When inlining a call site that has a byval argument, 564/// we have to make the implicit memcpy explicit by adding it. 565static Value *HandleByValArgument(Value *Arg, Instruction *TheCall, 566 const Function *CalledFunc, 567 InlineFunctionInfo &IFI, 568 unsigned ByValAlignment) { 569 Type *AggTy = cast<PointerType>(Arg->getType())->getElementType(); 570 571 // If the called function is readonly, then it could not mutate the caller's 572 // copy of the byval'd memory. In this case, it is safe to elide the copy and 573 // temporary. 574 if (CalledFunc->onlyReadsMemory()) { 575 // If the byval argument has a specified alignment that is greater than the 576 // passed in pointer, then we either have to round up the input pointer or 577 // give up on this transformation. 578 if (ByValAlignment <= 1) // 0 = unspecified, 1 = no particular alignment. 579 return Arg; 580 581 // If the pointer is already known to be sufficiently aligned, or if we can 582 // round it up to a larger alignment, then we don't need a temporary. 583 if (getOrEnforceKnownAlignment(Arg, ByValAlignment, 584 IFI.TD) >= ByValAlignment) 585 return Arg; 586 587 // Otherwise, we have to make a memcpy to get a safe alignment. This is bad 588 // for code quality, but rarely happens and is required for correctness. 589 } 590 591 LLVMContext &Context = Arg->getContext(); 592 593 Type *VoidPtrTy = Type::getInt8PtrTy(Context); 594 595 // Create the alloca. If we have TargetData, use nice alignment. 596 unsigned Align = 1; 597 if (IFI.TD) 598 Align = IFI.TD->getPrefTypeAlignment(AggTy); 599 600 // If the byval had an alignment specified, we *must* use at least that 601 // alignment, as it is required by the byval argument (and uses of the 602 // pointer inside the callee). 603 Align = std::max(Align, ByValAlignment); 604 605 Function *Caller = TheCall->getParent()->getParent(); 606 607 Value *NewAlloca = new AllocaInst(AggTy, 0, Align, Arg->getName(), 608 &*Caller->begin()->begin()); 609 // Emit a memcpy. 610 Type *Tys[3] = {VoidPtrTy, VoidPtrTy, Type::getInt64Ty(Context)}; 611 Function *MemCpyFn = Intrinsic::getDeclaration(Caller->getParent(), 612 Intrinsic::memcpy, 613 Tys); 614 Value *DestCast = new BitCastInst(NewAlloca, VoidPtrTy, "tmp", TheCall); 615 Value *SrcCast = new BitCastInst(Arg, VoidPtrTy, "tmp", TheCall); 616 617 Value *Size; 618 if (IFI.TD == 0) 619 Size = ConstantExpr::getSizeOf(AggTy); 620 else 621 Size = ConstantInt::get(Type::getInt64Ty(Context), 622 IFI.TD->getTypeStoreSize(AggTy)); 623 624 // Always generate a memcpy of alignment 1 here because we don't know 625 // the alignment of the src pointer. Other optimizations can infer 626 // better alignment. 627 Value *CallArgs[] = { 628 DestCast, SrcCast, Size, 629 ConstantInt::get(Type::getInt32Ty(Context), 1), 630 ConstantInt::getFalse(Context) // isVolatile 631 }; 632 IRBuilder<>(TheCall).CreateCall(MemCpyFn, CallArgs); 633 634 // Uses of the argument in the function should use our new alloca 635 // instead. 636 return NewAlloca; 637} 638 639// isUsedByLifetimeMarker - Check whether this Value is used by a lifetime 640// intrinsic. 641static bool isUsedByLifetimeMarker(Value *V) { 642 for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE; 643 ++UI) { 644 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*UI)) { 645 switch (II->getIntrinsicID()) { 646 default: break; 647 case Intrinsic::lifetime_start: 648 case Intrinsic::lifetime_end: 649 return true; 650 } 651 } 652 } 653 return false; 654} 655 656// hasLifetimeMarkers - Check whether the given alloca already has 657// lifetime.start or lifetime.end intrinsics. 658static bool hasLifetimeMarkers(AllocaInst *AI) { 659 Type *Int8PtrTy = Type::getInt8PtrTy(AI->getType()->getContext()); 660 if (AI->getType() == Int8PtrTy) 661 return isUsedByLifetimeMarker(AI); 662 663 // Do a scan to find all the casts to i8*. 664 for (Value::use_iterator I = AI->use_begin(), E = AI->use_end(); I != E; 665 ++I) { 666 if (I->getType() != Int8PtrTy) continue; 667 if (I->stripPointerCasts() != AI) continue; 668 if (isUsedByLifetimeMarker(*I)) 669 return true; 670 } 671 return false; 672} 673 674/// updateInlinedAtInfo - Helper function used by fixupLineNumbers to recursively 675/// update InlinedAtEntry of a DebugLoc. 676static DebugLoc updateInlinedAtInfo(const DebugLoc &DL, 677 const DebugLoc &InlinedAtDL, 678 LLVMContext &Ctx) { 679 if (MDNode *IA = DL.getInlinedAt(Ctx)) { 680 DebugLoc NewInlinedAtDL 681 = updateInlinedAtInfo(DebugLoc::getFromDILocation(IA), InlinedAtDL, Ctx); 682 return DebugLoc::get(DL.getLine(), DL.getCol(), DL.getScope(Ctx), 683 NewInlinedAtDL.getAsMDNode(Ctx)); 684 } 685 686 return DebugLoc::get(DL.getLine(), DL.getCol(), DL.getScope(Ctx), 687 InlinedAtDL.getAsMDNode(Ctx)); 688} 689 690/// fixupLineNumbers - Update inlined instructions' line numbers to 691/// to encode location where these instructions are inlined. 692static void fixupLineNumbers(Function *Fn, Function::iterator FI, 693 Instruction *TheCall) { 694 DebugLoc TheCallDL = TheCall->getDebugLoc(); 695 if (TheCallDL.isUnknown()) 696 return; 697 698 for (; FI != Fn->end(); ++FI) { 699 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end(); 700 BI != BE; ++BI) { 701 DebugLoc DL = BI->getDebugLoc(); 702 if (!DL.isUnknown()) { 703 BI->setDebugLoc(updateInlinedAtInfo(DL, TheCallDL, BI->getContext())); 704 if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(BI)) { 705 LLVMContext &Ctx = BI->getContext(); 706 MDNode *InlinedAt = BI->getDebugLoc().getInlinedAt(Ctx); 707 DVI->setOperand(2, createInlinedVariable(DVI->getVariable(), 708 InlinedAt, Ctx)); 709 } 710 } 711 } 712 } 713} 714 715/// InlineFunction - This function inlines the called function into the basic 716/// block of the caller. This returns false if it is not possible to inline 717/// this call. The program is still in a well defined state if this occurs 718/// though. 719/// 720/// Note that this only does one level of inlining. For example, if the 721/// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now 722/// exists in the instruction stream. Similarly this will inline a recursive 723/// function by one level. 724bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI) { 725 Instruction *TheCall = CS.getInstruction(); 726 LLVMContext &Context = TheCall->getContext(); 727 assert(TheCall->getParent() && TheCall->getParent()->getParent() && 728 "Instruction not in function!"); 729 730 // If IFI has any state in it, zap it before we fill it in. 731 IFI.reset(); 732 733 const Function *CalledFunc = CS.getCalledFunction(); 734 if (CalledFunc == 0 || // Can't inline external function or indirect 735 CalledFunc->isDeclaration() || // call, or call to a vararg function! 736 CalledFunc->getFunctionType()->isVarArg()) return false; 737 738 // If the call to the callee is not a tail call, we must clear the 'tail' 739 // flags on any calls that we inline. 740 bool MustClearTailCallFlags = 741 !(isa<CallInst>(TheCall) && cast<CallInst>(TheCall)->isTailCall()); 742 743 // If the call to the callee cannot throw, set the 'nounwind' flag on any 744 // calls that we inline. 745 bool MarkNoUnwind = CS.doesNotThrow(); 746 747 BasicBlock *OrigBB = TheCall->getParent(); 748 Function *Caller = OrigBB->getParent(); 749 750 // GC poses two hazards to inlining, which only occur when the callee has GC: 751 // 1. If the caller has no GC, then the callee's GC must be propagated to the 752 // caller. 753 // 2. If the caller has a differing GC, it is invalid to inline. 754 if (CalledFunc->hasGC()) { 755 if (!Caller->hasGC()) 756 Caller->setGC(CalledFunc->getGC()); 757 else if (CalledFunc->getGC() != Caller->getGC()) 758 return false; 759 } 760 761 // Get the personality function from the callee if it contains a landing pad. 762 Value *CalleePersonality = 0; 763 for (Function::const_iterator I = CalledFunc->begin(), E = CalledFunc->end(); 764 I != E; ++I) 765 if (const InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator())) { 766 const BasicBlock *BB = II->getUnwindDest(); 767 const LandingPadInst *LP = BB->getLandingPadInst(); 768 CalleePersonality = LP->getPersonalityFn(); 769 break; 770 } 771 772 // Find the personality function used by the landing pads of the caller. If it 773 // exists, then check to see that it matches the personality function used in 774 // the callee. 775 if (CalleePersonality) { 776 for (Function::const_iterator I = Caller->begin(), E = Caller->end(); 777 I != E; ++I) 778 if (const InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator())) { 779 const BasicBlock *BB = II->getUnwindDest(); 780 const LandingPadInst *LP = BB->getLandingPadInst(); 781 782 // If the personality functions match, then we can perform the 783 // inlining. Otherwise, we can't inline. 784 // TODO: This isn't 100% true. Some personality functions are proper 785 // supersets of others and can be used in place of the other. 786 if (LP->getPersonalityFn() != CalleePersonality) 787 return false; 788 789 break; 790 } 791 } 792 793 // Get an iterator to the last basic block in the function, which will have 794 // the new function inlined after it. 795 Function::iterator LastBlock = &Caller->back(); 796 797 // Make sure to capture all of the return instructions from the cloned 798 // function. 799 SmallVector<ReturnInst*, 8> Returns; 800 ClonedCodeInfo InlinedFunctionInfo; 801 Function::iterator FirstNewBlock; 802 803 { // Scope to destroy VMap after cloning. 804 ValueToValueMapTy VMap; 805 806 assert(CalledFunc->arg_size() == CS.arg_size() && 807 "No varargs calls can be inlined!"); 808 809 // Calculate the vector of arguments to pass into the function cloner, which 810 // matches up the formal to the actual argument values. 811 CallSite::arg_iterator AI = CS.arg_begin(); 812 unsigned ArgNo = 0; 813 for (Function::const_arg_iterator I = CalledFunc->arg_begin(), 814 E = CalledFunc->arg_end(); I != E; ++I, ++AI, ++ArgNo) { 815 Value *ActualArg = *AI; 816 817 // When byval arguments actually inlined, we need to make the copy implied 818 // by them explicit. However, we don't do this if the callee is readonly 819 // or readnone, because the copy would be unneeded: the callee doesn't 820 // modify the struct. 821 if (CS.isByValArgument(ArgNo)) { 822 ActualArg = HandleByValArgument(ActualArg, TheCall, CalledFunc, IFI, 823 CalledFunc->getParamAlignment(ArgNo+1)); 824 825 // Calls that we inline may use the new alloca, so we need to clear 826 // their 'tail' flags if HandleByValArgument introduced a new alloca and 827 // the callee has calls. 828 MustClearTailCallFlags |= ActualArg != *AI; 829 } 830 831 VMap[I] = ActualArg; 832 } 833 834 // We want the inliner to prune the code as it copies. We would LOVE to 835 // have no dead or constant instructions leftover after inlining occurs 836 // (which can happen, e.g., because an argument was constant), but we'll be 837 // happy with whatever the cloner can do. 838 CloneAndPruneFunctionInto(Caller, CalledFunc, VMap, 839 /*ModuleLevelChanges=*/false, Returns, ".i", 840 &InlinedFunctionInfo, IFI.TD, TheCall); 841 842 // Remember the first block that is newly cloned over. 843 FirstNewBlock = LastBlock; ++FirstNewBlock; 844 845 // Update the callgraph if requested. 846 if (IFI.CG) 847 UpdateCallGraphAfterInlining(CS, FirstNewBlock, VMap, IFI); 848 849 // Update inlined instructions' line number information. 850 fixupLineNumbers(Caller, FirstNewBlock, TheCall); 851 } 852 853 // If there are any alloca instructions in the block that used to be the entry 854 // block for the callee, move them to the entry block of the caller. First 855 // calculate which instruction they should be inserted before. We insert the 856 // instructions at the end of the current alloca list. 857 { 858 BasicBlock::iterator InsertPoint = Caller->begin()->begin(); 859 for (BasicBlock::iterator I = FirstNewBlock->begin(), 860 E = FirstNewBlock->end(); I != E; ) { 861 AllocaInst *AI = dyn_cast<AllocaInst>(I++); 862 if (AI == 0) continue; 863 864 // If the alloca is now dead, remove it. This often occurs due to code 865 // specialization. 866 if (AI->use_empty()) { 867 AI->eraseFromParent(); 868 continue; 869 } 870 871 if (!isa<Constant>(AI->getArraySize())) 872 continue; 873 874 // Keep track of the static allocas that we inline into the caller. 875 IFI.StaticAllocas.push_back(AI); 876 877 // Scan for the block of allocas that we can move over, and move them 878 // all at once. 879 while (isa<AllocaInst>(I) && 880 isa<Constant>(cast<AllocaInst>(I)->getArraySize())) { 881 IFI.StaticAllocas.push_back(cast<AllocaInst>(I)); 882 ++I; 883 } 884 885 // Transfer all of the allocas over in a block. Using splice means 886 // that the instructions aren't removed from the symbol table, then 887 // reinserted. 888 Caller->getEntryBlock().getInstList().splice(InsertPoint, 889 FirstNewBlock->getInstList(), 890 AI, I); 891 } 892 } 893 894 // Leave lifetime markers for the static alloca's, scoping them to the 895 // function we just inlined. 896 if (!IFI.StaticAllocas.empty()) { 897 IRBuilder<> builder(FirstNewBlock->begin()); 898 for (unsigned ai = 0, ae = IFI.StaticAllocas.size(); ai != ae; ++ai) { 899 AllocaInst *AI = IFI.StaticAllocas[ai]; 900 901 // If the alloca is already scoped to something smaller than the whole 902 // function then there's no need to add redundant, less accurate markers. 903 if (hasLifetimeMarkers(AI)) 904 continue; 905 906 builder.CreateLifetimeStart(AI); 907 for (unsigned ri = 0, re = Returns.size(); ri != re; ++ri) { 908 IRBuilder<> builder(Returns[ri]); 909 builder.CreateLifetimeEnd(AI); 910 } 911 } 912 } 913 914 // If the inlined code contained dynamic alloca instructions, wrap the inlined 915 // code with llvm.stacksave/llvm.stackrestore intrinsics. 916 if (InlinedFunctionInfo.ContainsDynamicAllocas) { 917 Module *M = Caller->getParent(); 918 // Get the two intrinsics we care about. 919 Function *StackSave = Intrinsic::getDeclaration(M, Intrinsic::stacksave); 920 Function *StackRestore=Intrinsic::getDeclaration(M,Intrinsic::stackrestore); 921 922 // Insert the llvm.stacksave. 923 CallInst *SavedPtr = IRBuilder<>(FirstNewBlock, FirstNewBlock->begin()) 924 .CreateCall(StackSave, "savedstack"); 925 926 // Insert a call to llvm.stackrestore before any return instructions in the 927 // inlined function. 928 for (unsigned i = 0, e = Returns.size(); i != e; ++i) { 929 IRBuilder<>(Returns[i]).CreateCall(StackRestore, SavedPtr); 930 } 931 932 // Count the number of StackRestore calls we insert. 933 unsigned NumStackRestores = Returns.size(); 934 935 // If we are inlining an invoke instruction, insert restores before each 936 // unwind. These unwinds will be rewritten into branches later. 937 if (InlinedFunctionInfo.ContainsUnwinds && isa<InvokeInst>(TheCall)) { 938 for (Function::iterator BB = FirstNewBlock, E = Caller->end(); 939 BB != E; ++BB) 940 if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { 941 IRBuilder<>(UI).CreateCall(StackRestore, SavedPtr); 942 ++NumStackRestores; 943 } 944 } 945 } 946 947 // If we are inlining tail call instruction through a call site that isn't 948 // marked 'tail', we must remove the tail marker for any calls in the inlined 949 // code. Also, calls inlined through a 'nounwind' call site should be marked 950 // 'nounwind'. 951 if (InlinedFunctionInfo.ContainsCalls && 952 (MustClearTailCallFlags || MarkNoUnwind)) { 953 for (Function::iterator BB = FirstNewBlock, E = Caller->end(); 954 BB != E; ++BB) 955 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 956 if (CallInst *CI = dyn_cast<CallInst>(I)) { 957 if (MustClearTailCallFlags) 958 CI->setTailCall(false); 959 if (MarkNoUnwind) 960 CI->setDoesNotThrow(); 961 } 962 } 963 964 // If we are inlining through a 'nounwind' call site then any inlined 'unwind' 965 // instructions are unreachable. 966 if (InlinedFunctionInfo.ContainsUnwinds && MarkNoUnwind) 967 for (Function::iterator BB = FirstNewBlock, E = Caller->end(); 968 BB != E; ++BB) { 969 TerminatorInst *Term = BB->getTerminator(); 970 if (isa<UnwindInst>(Term)) { 971 new UnreachableInst(Context, Term); 972 BB->getInstList().erase(Term); 973 } 974 } 975 976 // If we are inlining for an invoke instruction, we must make sure to rewrite 977 // any inlined 'unwind' instructions into branches to the invoke exception 978 // destination, and call instructions into invoke instructions. 979 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) 980 HandleInlinedInvoke(II, FirstNewBlock, InlinedFunctionInfo); 981 982 // If we cloned in _exactly one_ basic block, and if that block ends in a 983 // return instruction, we splice the body of the inlined callee directly into 984 // the calling basic block. 985 if (Returns.size() == 1 && std::distance(FirstNewBlock, Caller->end()) == 1) { 986 // Move all of the instructions right before the call. 987 OrigBB->getInstList().splice(TheCall, FirstNewBlock->getInstList(), 988 FirstNewBlock->begin(), FirstNewBlock->end()); 989 // Remove the cloned basic block. 990 Caller->getBasicBlockList().pop_back(); 991 992 // If the call site was an invoke instruction, add a branch to the normal 993 // destination. 994 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) 995 BranchInst::Create(II->getNormalDest(), TheCall); 996 997 // If the return instruction returned a value, replace uses of the call with 998 // uses of the returned value. 999 if (!TheCall->use_empty()) { 1000 ReturnInst *R = Returns[0]; 1001 if (TheCall == R->getReturnValue()) 1002 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType())); 1003 else 1004 TheCall->replaceAllUsesWith(R->getReturnValue()); 1005 } 1006 // Since we are now done with the Call/Invoke, we can delete it. 1007 TheCall->eraseFromParent(); 1008 1009 // Since we are now done with the return instruction, delete it also. 1010 Returns[0]->eraseFromParent(); 1011 1012 // We are now done with the inlining. 1013 return true; 1014 } 1015 1016 // Otherwise, we have the normal case, of more than one block to inline or 1017 // multiple return sites. 1018 1019 // We want to clone the entire callee function into the hole between the 1020 // "starter" and "ender" blocks. How we accomplish this depends on whether 1021 // this is an invoke instruction or a call instruction. 1022 BasicBlock *AfterCallBB; 1023 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) { 1024 1025 // Add an unconditional branch to make this look like the CallInst case... 1026 BranchInst *NewBr = BranchInst::Create(II->getNormalDest(), TheCall); 1027 1028 // Split the basic block. This guarantees that no PHI nodes will have to be 1029 // updated due to new incoming edges, and make the invoke case more 1030 // symmetric to the call case. 1031 AfterCallBB = OrigBB->splitBasicBlock(NewBr, 1032 CalledFunc->getName()+".exit"); 1033 1034 } else { // It's a call 1035 // If this is a call instruction, we need to split the basic block that 1036 // the call lives in. 1037 // 1038 AfterCallBB = OrigBB->splitBasicBlock(TheCall, 1039 CalledFunc->getName()+".exit"); 1040 } 1041 1042 // Change the branch that used to go to AfterCallBB to branch to the first 1043 // basic block of the inlined function. 1044 // 1045 TerminatorInst *Br = OrigBB->getTerminator(); 1046 assert(Br && Br->getOpcode() == Instruction::Br && 1047 "splitBasicBlock broken!"); 1048 Br->setOperand(0, FirstNewBlock); 1049 1050 1051 // Now that the function is correct, make it a little bit nicer. In 1052 // particular, move the basic blocks inserted from the end of the function 1053 // into the space made by splitting the source basic block. 1054 Caller->getBasicBlockList().splice(AfterCallBB, Caller->getBasicBlockList(), 1055 FirstNewBlock, Caller->end()); 1056 1057 // Handle all of the return instructions that we just cloned in, and eliminate 1058 // any users of the original call/invoke instruction. 1059 Type *RTy = CalledFunc->getReturnType(); 1060 1061 PHINode *PHI = 0; 1062 if (Returns.size() > 1) { 1063 // The PHI node should go at the front of the new basic block to merge all 1064 // possible incoming values. 1065 if (!TheCall->use_empty()) { 1066 PHI = PHINode::Create(RTy, Returns.size(), TheCall->getName(), 1067 AfterCallBB->begin()); 1068 // Anything that used the result of the function call should now use the 1069 // PHI node as their operand. 1070 TheCall->replaceAllUsesWith(PHI); 1071 } 1072 1073 // Loop over all of the return instructions adding entries to the PHI node 1074 // as appropriate. 1075 if (PHI) { 1076 for (unsigned i = 0, e = Returns.size(); i != e; ++i) { 1077 ReturnInst *RI = Returns[i]; 1078 assert(RI->getReturnValue()->getType() == PHI->getType() && 1079 "Ret value not consistent in function!"); 1080 PHI->addIncoming(RI->getReturnValue(), RI->getParent()); 1081 } 1082 } 1083 1084 1085 // Add a branch to the merge points and remove return instructions. 1086 for (unsigned i = 0, e = Returns.size(); i != e; ++i) { 1087 ReturnInst *RI = Returns[i]; 1088 BranchInst::Create(AfterCallBB, RI); 1089 RI->eraseFromParent(); 1090 } 1091 } else if (!Returns.empty()) { 1092 // Otherwise, if there is exactly one return value, just replace anything 1093 // using the return value of the call with the computed value. 1094 if (!TheCall->use_empty()) { 1095 if (TheCall == Returns[0]->getReturnValue()) 1096 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType())); 1097 else 1098 TheCall->replaceAllUsesWith(Returns[0]->getReturnValue()); 1099 } 1100 1101 // Update PHI nodes that use the ReturnBB to use the AfterCallBB. 1102 BasicBlock *ReturnBB = Returns[0]->getParent(); 1103 ReturnBB->replaceAllUsesWith(AfterCallBB); 1104 1105 // Splice the code from the return block into the block that it will return 1106 // to, which contains the code that was after the call. 1107 AfterCallBB->getInstList().splice(AfterCallBB->begin(), 1108 ReturnBB->getInstList()); 1109 1110 // Delete the return instruction now and empty ReturnBB now. 1111 Returns[0]->eraseFromParent(); 1112 ReturnBB->eraseFromParent(); 1113 } else if (!TheCall->use_empty()) { 1114 // No returns, but something is using the return value of the call. Just 1115 // nuke the result. 1116 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType())); 1117 } 1118 1119 // Since we are now done with the Call/Invoke, we can delete it. 1120 TheCall->eraseFromParent(); 1121 1122 // We should always be able to fold the entry block of the function into the 1123 // single predecessor of the block... 1124 assert(cast<BranchInst>(Br)->isUnconditional() && "splitBasicBlock broken!"); 1125 BasicBlock *CalleeEntry = cast<BranchInst>(Br)->getSuccessor(0); 1126 1127 // Splice the code entry block into calling block, right before the 1128 // unconditional branch. 1129 CalleeEntry->replaceAllUsesWith(OrigBB); // Update PHI nodes 1130 OrigBB->getInstList().splice(Br, CalleeEntry->getInstList()); 1131 1132 // Remove the unconditional branch. 1133 OrigBB->getInstList().erase(Br); 1134 1135 // Now we can remove the CalleeEntry block, which is now empty. 1136 Caller->getBasicBlockList().erase(CalleeEntry); 1137 1138 // If we inserted a phi node, check to see if it has a single value (e.g. all 1139 // the entries are the same or undef). If so, remove the PHI so it doesn't 1140 // block other optimizations. 1141 if (PHI) { 1142 if (Value *V = SimplifyInstruction(PHI, IFI.TD)) { 1143 PHI->replaceAllUsesWith(V); 1144 PHI->eraseFromParent(); 1145 } 1146 } 1147 1148 return true; 1149} 1150