InlineFunction.cpp revision a6d7345ec91e4b07671f62d231e7c42f054bc70d
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/// [LIBUNWIND] Find the (possibly absent) call to @llvm.eh.selector in 49/// the given landing pad. 50static EHSelectorInst *findSelectorForLandingPad(BasicBlock *lpad) { 51 // The llvm.eh.exception call is required to be in the landing pad. 52 for (BasicBlock::iterator i = lpad->begin(), e = lpad->end(); i != e; i++) { 53 EHExceptionInst *exn = dyn_cast<EHExceptionInst>(i); 54 if (!exn) continue; 55 56 EHSelectorInst *selector = 0; 57 for (Instruction::use_iterator 58 ui = exn->use_begin(), ue = exn->use_end(); ui != ue; ++ui) { 59 EHSelectorInst *sel = dyn_cast<EHSelectorInst>(*ui); 60 if (!sel) continue; 61 62 // Immediately accept an eh.selector in the landing pad. 63 if (sel->getParent() == lpad) return sel; 64 65 // Otherwise, use the first selector we see. 66 if (!selector) selector = sel; 67 } 68 69 return selector; 70 } 71 72 return 0; 73} 74 75namespace { 76 /// A class for recording information about inlining through an invoke. 77 class InvokeInliningInfo { 78 BasicBlock *OuterUnwindDest; 79 EHSelectorInst *OuterSelector; 80 BasicBlock *InnerUnwindDest; 81 PHINode *InnerExceptionPHI; 82 PHINode *InnerSelectorPHI; 83 SmallVector<Value*, 8> UnwindDestPHIValues; 84 85 public: 86 InvokeInliningInfo(InvokeInst *II) : 87 OuterUnwindDest(II->getUnwindDest()), OuterSelector(0), 88 InnerUnwindDest(0), InnerExceptionPHI(0), InnerSelectorPHI(0) { 89 90 // If there are PHI nodes in the unwind destination block, we 91 // need to keep track of which values came into them from the 92 // invoke before removing the edge from this block. 93 llvm::BasicBlock *invokeBB = II->getParent(); 94 for (BasicBlock::iterator I = OuterUnwindDest->begin(); 95 isa<PHINode>(I); ++I) { 96 // Save the value to use for this edge. 97 PHINode *phi = cast<PHINode>(I); 98 UnwindDestPHIValues.push_back(phi->getIncomingValueForBlock(invokeBB)); 99 } 100 } 101 102 /// The outer unwind destination is the target of unwind edges 103 /// introduced for calls within the inlined function. 104 BasicBlock *getOuterUnwindDest() const { 105 return OuterUnwindDest; 106 } 107 108 EHSelectorInst *getOuterSelector() { 109 if (!OuterSelector) 110 OuterSelector = findSelectorForLandingPad(OuterUnwindDest); 111 return OuterSelector; 112 } 113 114 BasicBlock *getInnerUnwindDest(); 115 116 bool forwardEHResume(CallInst *call, BasicBlock *src); 117 118 /// Add incoming-PHI values to the unwind destination block for 119 /// the given basic block, using the values for the original 120 /// invoke's source block. 121 void addIncomingPHIValuesFor(BasicBlock *BB) const { 122 addIncomingPHIValuesForInto(BB, OuterUnwindDest); 123 } 124 125 void addIncomingPHIValuesForInto(BasicBlock *src, BasicBlock *dest) const { 126 BasicBlock::iterator I = dest->begin(); 127 for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) { 128 PHINode *phi = cast<PHINode>(I); 129 phi->addIncoming(UnwindDestPHIValues[i], src); 130 } 131 } 132 }; 133} 134 135/// Replace all the instruction uses of a value with a different value. 136/// This has the advantage of not screwing up the CallGraph. 137static void replaceAllInsnUsesWith(Instruction *insn, Value *replacement) { 138 for (Value::use_iterator i = insn->use_begin(), e = insn->use_end(); 139 i != e; ) { 140 Use &use = i.getUse(); 141 ++i; 142 if (isa<Instruction>(use.getUser())) 143 use.set(replacement); 144 } 145} 146 147/// Get or create a target for the branch out of rewritten calls to 148/// llvm.eh.resume. 149BasicBlock *InvokeInliningInfo::getInnerUnwindDest() { 150 if (InnerUnwindDest) return InnerUnwindDest; 151 152 // Find and hoist the llvm.eh.exception and llvm.eh.selector calls 153 // in the outer landing pad to immediately following the phis. 154 EHSelectorInst *selector = getOuterSelector(); 155 if (!selector) return 0; 156 157 // The call to llvm.eh.exception *must* be in the landing pad. 158 Instruction *exn = cast<Instruction>(selector->getArgOperand(0)); 159 assert(exn->getParent() == OuterUnwindDest); 160 161 // TODO: recognize when we've already done this, so that we don't 162 // get a linear number of these when inlining calls into lots of 163 // invokes with the same landing pad. 164 165 // Do the hoisting. 166 Instruction *splitPoint = exn->getParent()->getFirstNonPHI(); 167 assert(splitPoint != selector && "selector-on-exception dominance broken!"); 168 if (splitPoint == exn) { 169 selector->removeFromParent(); 170 selector->insertAfter(exn); 171 splitPoint = selector->getNextNode(); 172 } else { 173 exn->moveBefore(splitPoint); 174 selector->moveBefore(splitPoint); 175 } 176 177 // Split the landing pad. 178 InnerUnwindDest = OuterUnwindDest->splitBasicBlock(splitPoint, 179 OuterUnwindDest->getName() + ".body"); 180 181 // The number of incoming edges we expect to the inner landing pad. 182 const unsigned phiCapacity = 2; 183 184 // Create corresponding new phis for all the phis in the outer landing pad. 185 BasicBlock::iterator insertPoint = InnerUnwindDest->begin(); 186 BasicBlock::iterator I = OuterUnwindDest->begin(); 187 for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) { 188 PHINode *outerPhi = cast<PHINode>(I); 189 PHINode *innerPhi = PHINode::Create(outerPhi->getType(), phiCapacity, 190 outerPhi->getName() + ".lpad-body", 191 insertPoint); 192 outerPhi->replaceAllUsesWith(innerPhi); 193 innerPhi->addIncoming(outerPhi, OuterUnwindDest); 194 } 195 196 // Create a phi for the exception value... 197 InnerExceptionPHI = PHINode::Create(exn->getType(), phiCapacity, 198 "exn.lpad-body", insertPoint); 199 replaceAllInsnUsesWith(exn, InnerExceptionPHI); 200 selector->setArgOperand(0, exn); // restore this use 201 InnerExceptionPHI->addIncoming(exn, OuterUnwindDest); 202 203 // ...and the selector. 204 InnerSelectorPHI = PHINode::Create(selector->getType(), phiCapacity, 205 "selector.lpad-body", insertPoint); 206 replaceAllInsnUsesWith(selector, InnerSelectorPHI); 207 InnerSelectorPHI->addIncoming(selector, OuterUnwindDest); 208 209 // All done. 210 return InnerUnwindDest; 211} 212 213/// [LIBUNWIND] Try to forward the given call, which logically occurs 214/// at the end of the given block, as a branch to the inner unwind 215/// block. Returns true if the call was forwarded. 216bool InvokeInliningInfo::forwardEHResume(CallInst *call, BasicBlock *src) { 217 Function *fn = dyn_cast<Function>(call->getCalledValue()); 218 if (!fn || fn->getName() != "llvm.eh.resume") 219 return false; 220 221 // If this fails, maybe it should be a fatal error. 222 BasicBlock *dest = getInnerUnwindDest(); 223 if (!dest) return false; 224 225 // Make a branch. 226 BranchInst::Create(dest, src); 227 228 // Update the phis in the destination. They were inserted in an 229 // order which makes this work. 230 addIncomingPHIValuesForInto(src, dest); 231 InnerExceptionPHI->addIncoming(call->getArgOperand(0), src); 232 InnerSelectorPHI->addIncoming(call->getArgOperand(1), src); 233 234 return true; 235} 236 237/// [LIBUNWIND] Check whether this selector is "only cleanups": 238/// call i32 @llvm.eh.selector(blah, blah, i32 0) 239static bool isCleanupOnlySelector(EHSelectorInst *selector) { 240 if (selector->getNumArgOperands() != 3) return false; 241 ConstantInt *val = dyn_cast<ConstantInt>(selector->getArgOperand(2)); 242 return (val && val->isZero()); 243} 244 245/// HandleCallsInBlockInlinedThroughInvoke - When we inline a basic block into 246/// an invoke, we have to turn all of the calls that can throw into 247/// invokes. This function analyze BB to see if there are any calls, and if so, 248/// it rewrites them to be invokes that jump to InvokeDest and fills in the PHI 249/// nodes in that block with the values specified in InvokeDestPHIValues. 250/// 251/// Returns true to indicate that the next block should be skipped. 252static bool HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB, 253 InvokeInliningInfo &Invoke) { 254 for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) { 255 Instruction *I = BBI++; 256 257 // We only need to check for function calls: inlined invoke 258 // instructions require no special handling. 259 CallInst *CI = dyn_cast<CallInst>(I); 260 if (CI == 0) continue; 261 262 // LIBUNWIND: merge selector instructions. 263 if (EHSelectorInst *Inner = dyn_cast<EHSelectorInst>(CI)) { 264 EHSelectorInst *Outer = Invoke.getOuterSelector(); 265 if (!Outer) continue; 266 267 bool innerIsOnlyCleanup = isCleanupOnlySelector(Inner); 268 bool outerIsOnlyCleanup = isCleanupOnlySelector(Outer); 269 270 // If both selectors contain only cleanups, we don't need to do 271 // anything. TODO: this is really just a very specific instance 272 // of a much more general optimization. 273 if (innerIsOnlyCleanup && outerIsOnlyCleanup) continue; 274 275 // Otherwise, we just append the outer selector to the inner selector. 276 SmallVector<Value*, 16> NewSelector; 277 for (unsigned i = 0, e = Inner->getNumArgOperands(); i != e; ++i) 278 NewSelector.push_back(Inner->getArgOperand(i)); 279 for (unsigned i = 2, e = Outer->getNumArgOperands(); i != e; ++i) 280 NewSelector.push_back(Outer->getArgOperand(i)); 281 282 CallInst *NewInner = CallInst::Create(Inner->getCalledValue(), 283 NewSelector.begin(), 284 NewSelector.end(), 285 "", 286 Inner); 287 // No need to copy attributes, calling convention, etc. 288 NewInner->takeName(Inner); 289 Inner->replaceAllUsesWith(NewInner); 290 Inner->eraseFromParent(); 291 continue; 292 } 293 294 // If this call cannot unwind, don't convert it to an invoke. 295 if (CI->doesNotThrow()) 296 continue; 297 298 // Convert this function call into an invoke instruction. 299 // First, split the basic block. 300 BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc"); 301 302 // Delete the unconditional branch inserted by splitBasicBlock 303 BB->getInstList().pop_back(); 304 305 // LIBUNWIND: If this is a call to @llvm.eh.resume, just branch 306 // directly to the new landing pad. 307 if (Invoke.forwardEHResume(CI, BB)) { 308 // TODO: 'Split' is now unreachable; clean it up. 309 310 // We want to leave the original call intact so that the call 311 // graph and other structures won't get misled. We also have to 312 // avoid processing the next block, or we'll iterate here forever. 313 return true; 314 } 315 316 // Otherwise, create the new invoke instruction. 317 ImmutableCallSite CS(CI); 318 SmallVector<Value*, 8> InvokeArgs(CS.arg_begin(), CS.arg_end()); 319 InvokeInst *II = 320 InvokeInst::Create(CI->getCalledValue(), Split, 321 Invoke.getOuterUnwindDest(), 322 InvokeArgs.begin(), InvokeArgs.end(), 323 CI->getName(), BB); 324 II->setCallingConv(CI->getCallingConv()); 325 II->setAttributes(CI->getAttributes()); 326 327 // Make sure that anything using the call now uses the invoke! This also 328 // updates the CallGraph if present, because it uses a WeakVH. 329 CI->replaceAllUsesWith(II); 330 331 Split->getInstList().pop_front(); // Delete the original call 332 333 // Update any PHI nodes in the exceptional block to indicate that 334 // there is now a new entry in them. 335 Invoke.addIncomingPHIValuesFor(BB); 336 return false; 337 } 338 339 return false; 340} 341 342 343/// HandleInlinedInvoke - If we inlined an invoke site, we need to convert calls 344/// in the body of the inlined function into invokes and turn unwind 345/// instructions into branches to the invoke unwind dest. 346/// 347/// II is the invoke instruction being inlined. FirstNewBlock is the first 348/// block of the inlined code (the last block is the end of the function), 349/// and InlineCodeInfo is information about the code that got inlined. 350static void HandleInlinedInvoke(InvokeInst *II, BasicBlock *FirstNewBlock, 351 ClonedCodeInfo &InlinedCodeInfo) { 352 BasicBlock *InvokeDest = II->getUnwindDest(); 353 354 Function *Caller = FirstNewBlock->getParent(); 355 356 // The inlined code is currently at the end of the function, scan from the 357 // start of the inlined code to its end, checking for stuff we need to 358 // rewrite. If the code doesn't have calls or unwinds, we know there is 359 // nothing to rewrite. 360 if (!InlinedCodeInfo.ContainsCalls && !InlinedCodeInfo.ContainsUnwinds) { 361 // Now that everything is happy, we have one final detail. The PHI nodes in 362 // the exception destination block still have entries due to the original 363 // invoke instruction. Eliminate these entries (which might even delete the 364 // PHI node) now. 365 InvokeDest->removePredecessor(II->getParent()); 366 return; 367 } 368 369 InvokeInliningInfo Invoke(II); 370 371 for (Function::iterator BB = FirstNewBlock, E = Caller->end(); BB != E; ++BB){ 372 if (InlinedCodeInfo.ContainsCalls) 373 if (HandleCallsInBlockInlinedThroughInvoke(BB, Invoke)) { 374 // Honor a request to skip the next block. We don't need to 375 // consider UnwindInsts in this case either. 376 ++BB; 377 continue; 378 } 379 380 if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { 381 // An UnwindInst requires special handling when it gets inlined into an 382 // invoke site. Once this happens, we know that the unwind would cause 383 // a control transfer to the invoke exception destination, so we can 384 // transform it into a direct branch to the exception destination. 385 BranchInst::Create(InvokeDest, UI); 386 387 // Delete the unwind instruction! 388 UI->eraseFromParent(); 389 390 // Update any PHI nodes in the exceptional block to indicate that 391 // there is now a new entry in them. 392 Invoke.addIncomingPHIValuesFor(BB); 393 } 394 } 395 396 // Now that everything is happy, we have one final detail. The PHI nodes in 397 // the exception destination block still have entries due to the original 398 // invoke instruction. Eliminate these entries (which might even delete the 399 // PHI node) now. 400 InvokeDest->removePredecessor(II->getParent()); 401} 402 403/// UpdateCallGraphAfterInlining - Once we have cloned code over from a callee 404/// into the caller, update the specified callgraph to reflect the changes we 405/// made. Note that it's possible that not all code was copied over, so only 406/// some edges of the callgraph may remain. 407static void UpdateCallGraphAfterInlining(CallSite CS, 408 Function::iterator FirstNewBlock, 409 ValueToValueMapTy &VMap, 410 InlineFunctionInfo &IFI) { 411 CallGraph &CG = *IFI.CG; 412 const Function *Caller = CS.getInstruction()->getParent()->getParent(); 413 const Function *Callee = CS.getCalledFunction(); 414 CallGraphNode *CalleeNode = CG[Callee]; 415 CallGraphNode *CallerNode = CG[Caller]; 416 417 // Since we inlined some uninlined call sites in the callee into the caller, 418 // add edges from the caller to all of the callees of the callee. 419 CallGraphNode::iterator I = CalleeNode->begin(), E = CalleeNode->end(); 420 421 // Consider the case where CalleeNode == CallerNode. 422 CallGraphNode::CalledFunctionsVector CallCache; 423 if (CalleeNode == CallerNode) { 424 CallCache.assign(I, E); 425 I = CallCache.begin(); 426 E = CallCache.end(); 427 } 428 429 for (; I != E; ++I) { 430 const Value *OrigCall = I->first; 431 432 ValueToValueMapTy::iterator VMI = VMap.find(OrigCall); 433 // Only copy the edge if the call was inlined! 434 if (VMI == VMap.end() || VMI->second == 0) 435 continue; 436 437 // If the call was inlined, but then constant folded, there is no edge to 438 // add. Check for this case. 439 Instruction *NewCall = dyn_cast<Instruction>(VMI->second); 440 if (NewCall == 0) continue; 441 442 // Remember that this call site got inlined for the client of 443 // InlineFunction. 444 IFI.InlinedCalls.push_back(NewCall); 445 446 // It's possible that inlining the callsite will cause it to go from an 447 // indirect to a direct call by resolving a function pointer. If this 448 // happens, set the callee of the new call site to a more precise 449 // destination. This can also happen if the call graph node of the caller 450 // was just unnecessarily imprecise. 451 if (I->second->getFunction() == 0) 452 if (Function *F = CallSite(NewCall).getCalledFunction()) { 453 // Indirect call site resolved to direct call. 454 CallerNode->addCalledFunction(CallSite(NewCall), CG[F]); 455 456 continue; 457 } 458 459 CallerNode->addCalledFunction(CallSite(NewCall), I->second); 460 } 461 462 // Update the call graph by deleting the edge from Callee to Caller. We must 463 // do this after the loop above in case Caller and Callee are the same. 464 CallerNode->removeCallEdgeFor(CS); 465} 466 467/// HandleByValArgument - When inlining a call site that has a byval argument, 468/// we have to make the implicit memcpy explicit by adding it. 469static Value *HandleByValArgument(Value *Arg, Instruction *TheCall, 470 const Function *CalledFunc, 471 InlineFunctionInfo &IFI, 472 unsigned ByValAlignment) { 473 const Type *AggTy = cast<PointerType>(Arg->getType())->getElementType(); 474 475 // If the called function is readonly, then it could not mutate the caller's 476 // copy of the byval'd memory. In this case, it is safe to elide the copy and 477 // temporary. 478 if (CalledFunc->onlyReadsMemory()) { 479 // If the byval argument has a specified alignment that is greater than the 480 // passed in pointer, then we either have to round up the input pointer or 481 // give up on this transformation. 482 if (ByValAlignment <= 1) // 0 = unspecified, 1 = no particular alignment. 483 return Arg; 484 485 // If the pointer is already known to be sufficiently aligned, or if we can 486 // round it up to a larger alignment, then we don't need a temporary. 487 if (getOrEnforceKnownAlignment(Arg, ByValAlignment, 488 IFI.TD) >= ByValAlignment) 489 return Arg; 490 491 // Otherwise, we have to make a memcpy to get a safe alignment. This is bad 492 // for code quality, but rarely happens and is required for correctness. 493 } 494 495 LLVMContext &Context = Arg->getContext(); 496 497 const Type *VoidPtrTy = Type::getInt8PtrTy(Context); 498 499 // Create the alloca. If we have TargetData, use nice alignment. 500 unsigned Align = 1; 501 if (IFI.TD) 502 Align = IFI.TD->getPrefTypeAlignment(AggTy); 503 504 // If the byval had an alignment specified, we *must* use at least that 505 // alignment, as it is required by the byval argument (and uses of the 506 // pointer inside the callee). 507 Align = std::max(Align, ByValAlignment); 508 509 Function *Caller = TheCall->getParent()->getParent(); 510 511 Value *NewAlloca = new AllocaInst(AggTy, 0, Align, Arg->getName(), 512 &*Caller->begin()->begin()); 513 // Emit a memcpy. 514 const Type *Tys[3] = {VoidPtrTy, VoidPtrTy, Type::getInt64Ty(Context)}; 515 Function *MemCpyFn = Intrinsic::getDeclaration(Caller->getParent(), 516 Intrinsic::memcpy, 517 Tys, 3); 518 Value *DestCast = new BitCastInst(NewAlloca, VoidPtrTy, "tmp", TheCall); 519 Value *SrcCast = new BitCastInst(Arg, VoidPtrTy, "tmp", TheCall); 520 521 Value *Size; 522 if (IFI.TD == 0) 523 Size = ConstantExpr::getSizeOf(AggTy); 524 else 525 Size = ConstantInt::get(Type::getInt64Ty(Context), 526 IFI.TD->getTypeStoreSize(AggTy)); 527 528 // Always generate a memcpy of alignment 1 here because we don't know 529 // the alignment of the src pointer. Other optimizations can infer 530 // better alignment. 531 Value *CallArgs[] = { 532 DestCast, SrcCast, Size, 533 ConstantInt::get(Type::getInt32Ty(Context), 1), 534 ConstantInt::getFalse(Context) // isVolatile 535 }; 536 CallInst *TheMemCpy = 537 CallInst::Create(MemCpyFn, CallArgs, CallArgs+5, "", TheCall); 538 539 // If we have a call graph, update it. 540 if (CallGraph *CG = IFI.CG) { 541 CallGraphNode *MemCpyCGN = CG->getOrInsertFunction(MemCpyFn); 542 CallGraphNode *CallerNode = (*CG)[Caller]; 543 CallerNode->addCalledFunction(TheMemCpy, MemCpyCGN); 544 } 545 546 // Uses of the argument in the function should use our new alloca 547 // instead. 548 return NewAlloca; 549} 550 551// isUsedByLifetimeMarker - Check whether this Value is used by a lifetime 552// intrinsic. 553static bool isUsedByLifetimeMarker(Value *V) { 554 for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE; 555 ++UI) { 556 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*UI)) { 557 switch (II->getIntrinsicID()) { 558 default: break; 559 case Intrinsic::lifetime_start: 560 case Intrinsic::lifetime_end: 561 return true; 562 } 563 } 564 } 565 return false; 566} 567 568// hasLifetimeMarkers - Check whether the given alloca already has 569// lifetime.start or lifetime.end intrinsics. 570static bool hasLifetimeMarkers(AllocaInst *AI) { 571 const Type *Int8PtrTy = Type::getInt8PtrTy(AI->getType()->getContext()); 572 if (AI->getType() == Int8PtrTy) 573 return isUsedByLifetimeMarker(AI); 574 575 // Do a scan to find all the bitcasts to i8*. 576 for (Value::use_iterator I = AI->use_begin(), E = AI->use_end(); I != E; 577 ++I) { 578 if (I->getType() != Int8PtrTy) continue; 579 if (!isa<BitCastInst>(*I)) continue; 580 if (isUsedByLifetimeMarker(*I)) 581 return true; 582 } 583 return false; 584} 585 586// InlineFunction - This function inlines the called function into the basic 587// block of the caller. This returns false if it is not possible to inline this 588// call. The program is still in a well defined state if this occurs though. 589// 590// Note that this only does one level of inlining. For example, if the 591// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now 592// exists in the instruction stream. Similarly this will inline a recursive 593// function by one level. 594// 595bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI) { 596 Instruction *TheCall = CS.getInstruction(); 597 LLVMContext &Context = TheCall->getContext(); 598 assert(TheCall->getParent() && TheCall->getParent()->getParent() && 599 "Instruction not in function!"); 600 601 // If IFI has any state in it, zap it before we fill it in. 602 IFI.reset(); 603 604 const Function *CalledFunc = CS.getCalledFunction(); 605 if (CalledFunc == 0 || // Can't inline external function or indirect 606 CalledFunc->isDeclaration() || // call, or call to a vararg function! 607 CalledFunc->getFunctionType()->isVarArg()) return false; 608 609 // If the call to the callee is not a tail call, we must clear the 'tail' 610 // flags on any calls that we inline. 611 bool MustClearTailCallFlags = 612 !(isa<CallInst>(TheCall) && cast<CallInst>(TheCall)->isTailCall()); 613 614 // If the call to the callee cannot throw, set the 'nounwind' flag on any 615 // calls that we inline. 616 bool MarkNoUnwind = CS.doesNotThrow(); 617 618 BasicBlock *OrigBB = TheCall->getParent(); 619 Function *Caller = OrigBB->getParent(); 620 621 // GC poses two hazards to inlining, which only occur when the callee has GC: 622 // 1. If the caller has no GC, then the callee's GC must be propagated to the 623 // caller. 624 // 2. If the caller has a differing GC, it is invalid to inline. 625 if (CalledFunc->hasGC()) { 626 if (!Caller->hasGC()) 627 Caller->setGC(CalledFunc->getGC()); 628 else if (CalledFunc->getGC() != Caller->getGC()) 629 return false; 630 } 631 632 // Get an iterator to the last basic block in the function, which will have 633 // the new function inlined after it. 634 // 635 Function::iterator LastBlock = &Caller->back(); 636 637 // Make sure to capture all of the return instructions from the cloned 638 // function. 639 SmallVector<ReturnInst*, 8> Returns; 640 ClonedCodeInfo InlinedFunctionInfo; 641 Function::iterator FirstNewBlock; 642 643 { // Scope to destroy VMap after cloning. 644 ValueToValueMapTy VMap; 645 646 assert(CalledFunc->arg_size() == CS.arg_size() && 647 "No varargs calls can be inlined!"); 648 649 // Calculate the vector of arguments to pass into the function cloner, which 650 // matches up the formal to the actual argument values. 651 CallSite::arg_iterator AI = CS.arg_begin(); 652 unsigned ArgNo = 0; 653 for (Function::const_arg_iterator I = CalledFunc->arg_begin(), 654 E = CalledFunc->arg_end(); I != E; ++I, ++AI, ++ArgNo) { 655 Value *ActualArg = *AI; 656 657 // When byval arguments actually inlined, we need to make the copy implied 658 // by them explicit. However, we don't do this if the callee is readonly 659 // or readnone, because the copy would be unneeded: the callee doesn't 660 // modify the struct. 661 if (CalledFunc->paramHasAttr(ArgNo+1, Attribute::ByVal)) { 662 ActualArg = HandleByValArgument(ActualArg, TheCall, CalledFunc, IFI, 663 CalledFunc->getParamAlignment(ArgNo+1)); 664 665 // Calls that we inline may use the new alloca, so we need to clear 666 // their 'tail' flags if HandleByValArgument introduced a new alloca and 667 // the callee has calls. 668 MustClearTailCallFlags |= ActualArg != *AI; 669 } 670 671 VMap[I] = ActualArg; 672 } 673 674 // We want the inliner to prune the code as it copies. We would LOVE to 675 // have no dead or constant instructions leftover after inlining occurs 676 // (which can happen, e.g., because an argument was constant), but we'll be 677 // happy with whatever the cloner can do. 678 CloneAndPruneFunctionInto(Caller, CalledFunc, VMap, 679 /*ModuleLevelChanges=*/false, Returns, ".i", 680 &InlinedFunctionInfo, IFI.TD, TheCall); 681 682 // Remember the first block that is newly cloned over. 683 FirstNewBlock = LastBlock; ++FirstNewBlock; 684 685 // Update the callgraph if requested. 686 if (IFI.CG) 687 UpdateCallGraphAfterInlining(CS, FirstNewBlock, VMap, IFI); 688 } 689 690 // If there are any alloca instructions in the block that used to be the entry 691 // block for the callee, move them to the entry block of the caller. First 692 // calculate which instruction they should be inserted before. We insert the 693 // instructions at the end of the current alloca list. 694 // 695 { 696 BasicBlock::iterator InsertPoint = Caller->begin()->begin(); 697 for (BasicBlock::iterator I = FirstNewBlock->begin(), 698 E = FirstNewBlock->end(); I != E; ) { 699 AllocaInst *AI = dyn_cast<AllocaInst>(I++); 700 if (AI == 0) continue; 701 702 // If the alloca is now dead, remove it. This often occurs due to code 703 // specialization. 704 if (AI->use_empty()) { 705 AI->eraseFromParent(); 706 continue; 707 } 708 709 if (!isa<Constant>(AI->getArraySize())) 710 continue; 711 712 // Keep track of the static allocas that we inline into the caller. 713 IFI.StaticAllocas.push_back(AI); 714 715 // Scan for the block of allocas that we can move over, and move them 716 // all at once. 717 while (isa<AllocaInst>(I) && 718 isa<Constant>(cast<AllocaInst>(I)->getArraySize())) { 719 IFI.StaticAllocas.push_back(cast<AllocaInst>(I)); 720 ++I; 721 } 722 723 // Transfer all of the allocas over in a block. Using splice means 724 // that the instructions aren't removed from the symbol table, then 725 // reinserted. 726 Caller->getEntryBlock().getInstList().splice(InsertPoint, 727 FirstNewBlock->getInstList(), 728 AI, I); 729 } 730 } 731 732 // Leave lifetime markers for the static alloca's, scoping them to the 733 // function we just inlined. 734 if (!IFI.StaticAllocas.empty()) { 735 // Also preserve the call graph, if applicable. 736 CallGraphNode *StartCGN = 0, *EndCGN = 0, *CallerNode = 0; 737 if (CallGraph *CG = IFI.CG) { 738 Function *Start = Intrinsic::getDeclaration(Caller->getParent(), 739 Intrinsic::lifetime_start); 740 Function *End = Intrinsic::getDeclaration(Caller->getParent(), 741 Intrinsic::lifetime_end); 742 StartCGN = CG->getOrInsertFunction(Start); 743 EndCGN = CG->getOrInsertFunction(End); 744 CallerNode = (*CG)[Caller]; 745 } 746 747 IRBuilder<> builder(FirstNewBlock->begin()); 748 for (unsigned ai = 0, ae = IFI.StaticAllocas.size(); ai != ae; ++ai) { 749 AllocaInst *AI = IFI.StaticAllocas[ai]; 750 751 // If the alloca is already scoped to something smaller than the whole 752 // function then there's no need to add redundant, less accurate markers. 753 if (hasLifetimeMarkers(AI)) 754 continue; 755 756 CallInst *StartCall = builder.CreateLifetimeStart(AI); 757 if (IFI.CG) CallerNode->addCalledFunction(StartCall, StartCGN); 758 for (unsigned ri = 0, re = Returns.size(); ri != re; ++ri) { 759 IRBuilder<> builder(Returns[ri]); 760 CallInst *EndCall = builder.CreateLifetimeEnd(AI); 761 if (IFI.CG) CallerNode->addCalledFunction(EndCall, EndCGN); 762 } 763 } 764 } 765 766 // If the inlined code contained dynamic alloca instructions, wrap the inlined 767 // code with llvm.stacksave/llvm.stackrestore intrinsics. 768 if (InlinedFunctionInfo.ContainsDynamicAllocas) { 769 Module *M = Caller->getParent(); 770 // Get the two intrinsics we care about. 771 Function *StackSave = Intrinsic::getDeclaration(M, Intrinsic::stacksave); 772 Function *StackRestore=Intrinsic::getDeclaration(M,Intrinsic::stackrestore); 773 774 // If we are preserving the callgraph, add edges to the stacksave/restore 775 // functions for the calls we insert. 776 CallGraphNode *StackSaveCGN = 0, *StackRestoreCGN = 0, *CallerNode = 0; 777 if (CallGraph *CG = IFI.CG) { 778 StackSaveCGN = CG->getOrInsertFunction(StackSave); 779 StackRestoreCGN = CG->getOrInsertFunction(StackRestore); 780 CallerNode = (*CG)[Caller]; 781 } 782 783 // Insert the llvm.stacksave. 784 CallInst *SavedPtr = CallInst::Create(StackSave, "savedstack", 785 FirstNewBlock->begin()); 786 if (IFI.CG) CallerNode->addCalledFunction(SavedPtr, StackSaveCGN); 787 788 // Insert a call to llvm.stackrestore before any return instructions in the 789 // inlined function. 790 for (unsigned i = 0, e = Returns.size(); i != e; ++i) { 791 CallInst *CI = CallInst::Create(StackRestore, SavedPtr, "", Returns[i]); 792 if (IFI.CG) CallerNode->addCalledFunction(CI, StackRestoreCGN); 793 } 794 795 // Count the number of StackRestore calls we insert. 796 unsigned NumStackRestores = Returns.size(); 797 798 // If we are inlining an invoke instruction, insert restores before each 799 // unwind. These unwinds will be rewritten into branches later. 800 if (InlinedFunctionInfo.ContainsUnwinds && isa<InvokeInst>(TheCall)) { 801 for (Function::iterator BB = FirstNewBlock, E = Caller->end(); 802 BB != E; ++BB) 803 if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { 804 CallInst *CI = CallInst::Create(StackRestore, SavedPtr, "", UI); 805 if (IFI.CG) CallerNode->addCalledFunction(CI, StackRestoreCGN); 806 ++NumStackRestores; 807 } 808 } 809 } 810 811 // If we are inlining tail call instruction through a call site that isn't 812 // marked 'tail', we must remove the tail marker for any calls in the inlined 813 // code. Also, calls inlined through a 'nounwind' call site should be marked 814 // 'nounwind'. 815 if (InlinedFunctionInfo.ContainsCalls && 816 (MustClearTailCallFlags || MarkNoUnwind)) { 817 for (Function::iterator BB = FirstNewBlock, E = Caller->end(); 818 BB != E; ++BB) 819 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 820 if (CallInst *CI = dyn_cast<CallInst>(I)) { 821 if (MustClearTailCallFlags) 822 CI->setTailCall(false); 823 if (MarkNoUnwind) 824 CI->setDoesNotThrow(); 825 } 826 } 827 828 // If we are inlining through a 'nounwind' call site then any inlined 'unwind' 829 // instructions are unreachable. 830 if (InlinedFunctionInfo.ContainsUnwinds && MarkNoUnwind) 831 for (Function::iterator BB = FirstNewBlock, E = Caller->end(); 832 BB != E; ++BB) { 833 TerminatorInst *Term = BB->getTerminator(); 834 if (isa<UnwindInst>(Term)) { 835 new UnreachableInst(Context, Term); 836 BB->getInstList().erase(Term); 837 } 838 } 839 840 // If we are inlining for an invoke instruction, we must make sure to rewrite 841 // any inlined 'unwind' instructions into branches to the invoke exception 842 // destination, and call instructions into invoke instructions. 843 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) 844 HandleInlinedInvoke(II, FirstNewBlock, InlinedFunctionInfo); 845 846 // If we cloned in _exactly one_ basic block, and if that block ends in a 847 // return instruction, we splice the body of the inlined callee directly into 848 // the calling basic block. 849 if (Returns.size() == 1 && std::distance(FirstNewBlock, Caller->end()) == 1) { 850 // Move all of the instructions right before the call. 851 OrigBB->getInstList().splice(TheCall, FirstNewBlock->getInstList(), 852 FirstNewBlock->begin(), FirstNewBlock->end()); 853 // Remove the cloned basic block. 854 Caller->getBasicBlockList().pop_back(); 855 856 // If the call site was an invoke instruction, add a branch to the normal 857 // destination. 858 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) 859 BranchInst::Create(II->getNormalDest(), TheCall); 860 861 // If the return instruction returned a value, replace uses of the call with 862 // uses of the returned value. 863 if (!TheCall->use_empty()) { 864 ReturnInst *R = Returns[0]; 865 if (TheCall == R->getReturnValue()) 866 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType())); 867 else 868 TheCall->replaceAllUsesWith(R->getReturnValue()); 869 } 870 // Since we are now done with the Call/Invoke, we can delete it. 871 TheCall->eraseFromParent(); 872 873 // Since we are now done with the return instruction, delete it also. 874 Returns[0]->eraseFromParent(); 875 876 // We are now done with the inlining. 877 return true; 878 } 879 880 // Otherwise, we have the normal case, of more than one block to inline or 881 // multiple return sites. 882 883 // We want to clone the entire callee function into the hole between the 884 // "starter" and "ender" blocks. How we accomplish this depends on whether 885 // this is an invoke instruction or a call instruction. 886 BasicBlock *AfterCallBB; 887 if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) { 888 889 // Add an unconditional branch to make this look like the CallInst case... 890 BranchInst *NewBr = BranchInst::Create(II->getNormalDest(), TheCall); 891 892 // Split the basic block. This guarantees that no PHI nodes will have to be 893 // updated due to new incoming edges, and make the invoke case more 894 // symmetric to the call case. 895 AfterCallBB = OrigBB->splitBasicBlock(NewBr, 896 CalledFunc->getName()+".exit"); 897 898 } else { // It's a call 899 // If this is a call instruction, we need to split the basic block that 900 // the call lives in. 901 // 902 AfterCallBB = OrigBB->splitBasicBlock(TheCall, 903 CalledFunc->getName()+".exit"); 904 } 905 906 // Change the branch that used to go to AfterCallBB to branch to the first 907 // basic block of the inlined function. 908 // 909 TerminatorInst *Br = OrigBB->getTerminator(); 910 assert(Br && Br->getOpcode() == Instruction::Br && 911 "splitBasicBlock broken!"); 912 Br->setOperand(0, FirstNewBlock); 913 914 915 // Now that the function is correct, make it a little bit nicer. In 916 // particular, move the basic blocks inserted from the end of the function 917 // into the space made by splitting the source basic block. 918 Caller->getBasicBlockList().splice(AfterCallBB, Caller->getBasicBlockList(), 919 FirstNewBlock, Caller->end()); 920 921 // Handle all of the return instructions that we just cloned in, and eliminate 922 // any users of the original call/invoke instruction. 923 const Type *RTy = CalledFunc->getReturnType(); 924 925 PHINode *PHI = 0; 926 if (Returns.size() > 1) { 927 // The PHI node should go at the front of the new basic block to merge all 928 // possible incoming values. 929 if (!TheCall->use_empty()) { 930 PHI = PHINode::Create(RTy, Returns.size(), TheCall->getName(), 931 AfterCallBB->begin()); 932 // Anything that used the result of the function call should now use the 933 // PHI node as their operand. 934 TheCall->replaceAllUsesWith(PHI); 935 } 936 937 // Loop over all of the return instructions adding entries to the PHI node 938 // as appropriate. 939 if (PHI) { 940 for (unsigned i = 0, e = Returns.size(); i != e; ++i) { 941 ReturnInst *RI = Returns[i]; 942 assert(RI->getReturnValue()->getType() == PHI->getType() && 943 "Ret value not consistent in function!"); 944 PHI->addIncoming(RI->getReturnValue(), RI->getParent()); 945 } 946 } 947 948 949 // Add a branch to the merge points and remove return instructions. 950 for (unsigned i = 0, e = Returns.size(); i != e; ++i) { 951 ReturnInst *RI = Returns[i]; 952 BranchInst::Create(AfterCallBB, RI); 953 RI->eraseFromParent(); 954 } 955 } else if (!Returns.empty()) { 956 // Otherwise, if there is exactly one return value, just replace anything 957 // using the return value of the call with the computed value. 958 if (!TheCall->use_empty()) { 959 if (TheCall == Returns[0]->getReturnValue()) 960 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType())); 961 else 962 TheCall->replaceAllUsesWith(Returns[0]->getReturnValue()); 963 } 964 965 // Splice the code from the return block into the block that it will return 966 // to, which contains the code that was after the call. 967 BasicBlock *ReturnBB = Returns[0]->getParent(); 968 AfterCallBB->getInstList().splice(AfterCallBB->begin(), 969 ReturnBB->getInstList()); 970 971 // Update PHI nodes that use the ReturnBB to use the AfterCallBB. 972 ReturnBB->replaceAllUsesWith(AfterCallBB); 973 974 // Delete the return instruction now and empty ReturnBB now. 975 Returns[0]->eraseFromParent(); 976 ReturnBB->eraseFromParent(); 977 } else if (!TheCall->use_empty()) { 978 // No returns, but something is using the return value of the call. Just 979 // nuke the result. 980 TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType())); 981 } 982 983 // Since we are now done with the Call/Invoke, we can delete it. 984 TheCall->eraseFromParent(); 985 986 // We should always be able to fold the entry block of the function into the 987 // single predecessor of the block... 988 assert(cast<BranchInst>(Br)->isUnconditional() && "splitBasicBlock broken!"); 989 BasicBlock *CalleeEntry = cast<BranchInst>(Br)->getSuccessor(0); 990 991 // Splice the code entry block into calling block, right before the 992 // unconditional branch. 993 OrigBB->getInstList().splice(Br, CalleeEntry->getInstList()); 994 CalleeEntry->replaceAllUsesWith(OrigBB); // Update PHI nodes 995 996 // Remove the unconditional branch. 997 OrigBB->getInstList().erase(Br); 998 999 // Now we can remove the CalleeEntry block, which is now empty. 1000 Caller->getBasicBlockList().erase(CalleeEntry); 1001 1002 // If we inserted a phi node, check to see if it has a single value (e.g. all 1003 // the entries are the same or undef). If so, remove the PHI so it doesn't 1004 // block other optimizations. 1005 if (PHI) 1006 if (Value *V = SimplifyInstruction(PHI, IFI.TD)) { 1007 PHI->replaceAllUsesWith(V); 1008 PHI->eraseFromParent(); 1009 } 1010 1011 return true; 1012} 1013