1 //===- CloneFunction.cpp - Clone a function into another function ---------===// 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 CloneFunctionInto interface, which is used as the 11 // low-level function cloner. This is used by the CloneFunction and function 12 // inliner to do the dirty work of copying the body of a function around. 13 // 14 //===----------------------------------------------------------------------===// 15 16 #include "llvm/Transforms/Utils/Cloning.h" 17 #include "llvm/Constants.h" 18 #include "llvm/DebugInfo.h" 19 #include "llvm/DerivedTypes.h" 20 #include "llvm/Instructions.h" 21 #include "llvm/IntrinsicInst.h" 22 #include "llvm/GlobalVariable.h" 23 #include "llvm/Function.h" 24 #include "llvm/LLVMContext.h" 25 #include "llvm/Metadata.h" 26 #include "llvm/Support/CFG.h" 27 #include "llvm/Transforms/Utils/BasicBlockUtils.h" 28 #include "llvm/Transforms/Utils/Local.h" 29 #include "llvm/Transforms/Utils/ValueMapper.h" 30 #include "llvm/Analysis/ConstantFolding.h" 31 #include "llvm/Analysis/InstructionSimplify.h" 32 #include "llvm/ADT/SmallVector.h" 33 #include <map> 34 using namespace llvm; 35 36 // CloneBasicBlock - See comments in Cloning.h 37 BasicBlock *llvm::CloneBasicBlock(const BasicBlock *BB, 38 ValueToValueMapTy &VMap, 39 const Twine &NameSuffix, Function *F, 40 ClonedCodeInfo *CodeInfo) { 41 BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "", F); 42 if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix); 43 44 bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false; 45 46 // Loop over all instructions, and copy them over. 47 for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end(); 48 II != IE; ++II) { 49 Instruction *NewInst = II->clone(); 50 if (II->hasName()) 51 NewInst->setName(II->getName()+NameSuffix); 52 NewBB->getInstList().push_back(NewInst); 53 VMap[II] = NewInst; // Add instruction map to value. 54 55 hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II)); 56 if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) { 57 if (isa<ConstantInt>(AI->getArraySize())) 58 hasStaticAllocas = true; 59 else 60 hasDynamicAllocas = true; 61 } 62 } 63 64 if (CodeInfo) { 65 CodeInfo->ContainsCalls |= hasCalls; 66 CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas; 67 CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas && 68 BB != &BB->getParent()->getEntryBlock(); 69 } 70 return NewBB; 71 } 72 73 // Clone OldFunc into NewFunc, transforming the old arguments into references to 74 // VMap values. 75 // 76 void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc, 77 ValueToValueMapTy &VMap, 78 bool ModuleLevelChanges, 79 SmallVectorImpl<ReturnInst*> &Returns, 80 const char *NameSuffix, ClonedCodeInfo *CodeInfo, 81 ValueMapTypeRemapper *TypeMapper) { 82 assert(NameSuffix && "NameSuffix cannot be null!"); 83 84 #ifndef NDEBUG 85 for (Function::const_arg_iterator I = OldFunc->arg_begin(), 86 E = OldFunc->arg_end(); I != E; ++I) 87 assert(VMap.count(I) && "No mapping from source argument specified!"); 88 #endif 89 90 // Clone any attributes. 91 if (NewFunc->arg_size() == OldFunc->arg_size()) 92 NewFunc->copyAttributesFrom(OldFunc); 93 else { 94 //Some arguments were deleted with the VMap. Copy arguments one by one 95 for (Function::const_arg_iterator I = OldFunc->arg_begin(), 96 E = OldFunc->arg_end(); I != E; ++I) 97 if (Argument* Anew = dyn_cast<Argument>(VMap[I])) 98 Anew->addAttr( OldFunc->getAttributes() 99 .getParamAttributes(I->getArgNo() + 1)); 100 NewFunc->setAttributes(NewFunc->getAttributes() 101 .addAttr(0, OldFunc->getAttributes() 102 .getRetAttributes())); 103 NewFunc->setAttributes(NewFunc->getAttributes() 104 .addAttr(~0, OldFunc->getAttributes() 105 .getFnAttributes())); 106 107 } 108 109 // Loop over all of the basic blocks in the function, cloning them as 110 // appropriate. Note that we save BE this way in order to handle cloning of 111 // recursive functions into themselves. 112 // 113 for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end(); 114 BI != BE; ++BI) { 115 const BasicBlock &BB = *BI; 116 117 // Create a new basic block and copy instructions into it! 118 BasicBlock *CBB = CloneBasicBlock(&BB, VMap, NameSuffix, NewFunc, CodeInfo); 119 120 // Add basic block mapping. 121 VMap[&BB] = CBB; 122 123 // It is only legal to clone a function if a block address within that 124 // function is never referenced outside of the function. Given that, we 125 // want to map block addresses from the old function to block addresses in 126 // the clone. (This is different from the generic ValueMapper 127 // implementation, which generates an invalid blockaddress when 128 // cloning a function.) 129 if (BB.hasAddressTaken()) { 130 Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc), 131 const_cast<BasicBlock*>(&BB)); 132 VMap[OldBBAddr] = BlockAddress::get(NewFunc, CBB); 133 } 134 135 // Note return instructions for the caller. 136 if (ReturnInst *RI = dyn_cast<ReturnInst>(CBB->getTerminator())) 137 Returns.push_back(RI); 138 } 139 140 // Loop over all of the instructions in the function, fixing up operand 141 // references as we go. This uses VMap to do all the hard work. 142 for (Function::iterator BB = cast<BasicBlock>(VMap[OldFunc->begin()]), 143 BE = NewFunc->end(); BB != BE; ++BB) 144 // Loop over all instructions, fixing each one as we find it... 145 for (BasicBlock::iterator II = BB->begin(); II != BB->end(); ++II) 146 RemapInstruction(II, VMap, 147 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges, 148 TypeMapper); 149 } 150 151 /// CloneFunction - Return a copy of the specified function, but without 152 /// embedding the function into another module. Also, any references specified 153 /// in the VMap are changed to refer to their mapped value instead of the 154 /// original one. If any of the arguments to the function are in the VMap, 155 /// the arguments are deleted from the resultant function. The VMap is 156 /// updated to include mappings from all of the instructions and basicblocks in 157 /// the function from their old to new values. 158 /// 159 Function *llvm::CloneFunction(const Function *F, ValueToValueMapTy &VMap, 160 bool ModuleLevelChanges, 161 ClonedCodeInfo *CodeInfo) { 162 std::vector<Type*> ArgTypes; 163 164 // The user might be deleting arguments to the function by specifying them in 165 // the VMap. If so, we need to not add the arguments to the arg ty vector 166 // 167 for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end(); 168 I != E; ++I) 169 if (VMap.count(I) == 0) // Haven't mapped the argument to anything yet? 170 ArgTypes.push_back(I->getType()); 171 172 // Create a new function type... 173 FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(), 174 ArgTypes, F->getFunctionType()->isVarArg()); 175 176 // Create the new function... 177 Function *NewF = Function::Create(FTy, F->getLinkage(), F->getName()); 178 179 // Loop over the arguments, copying the names of the mapped arguments over... 180 Function::arg_iterator DestI = NewF->arg_begin(); 181 for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end(); 182 I != E; ++I) 183 if (VMap.count(I) == 0) { // Is this argument preserved? 184 DestI->setName(I->getName()); // Copy the name over... 185 VMap[I] = DestI++; // Add mapping to VMap 186 } 187 188 SmallVector<ReturnInst*, 8> Returns; // Ignore returns cloned. 189 CloneFunctionInto(NewF, F, VMap, ModuleLevelChanges, Returns, "", CodeInfo); 190 return NewF; 191 } 192 193 194 195 namespace { 196 /// PruningFunctionCloner - This class is a private class used to implement 197 /// the CloneAndPruneFunctionInto method. 198 struct PruningFunctionCloner { 199 Function *NewFunc; 200 const Function *OldFunc; 201 ValueToValueMapTy &VMap; 202 bool ModuleLevelChanges; 203 const char *NameSuffix; 204 ClonedCodeInfo *CodeInfo; 205 const TargetData *TD; 206 public: 207 PruningFunctionCloner(Function *newFunc, const Function *oldFunc, 208 ValueToValueMapTy &valueMap, 209 bool moduleLevelChanges, 210 const char *nameSuffix, 211 ClonedCodeInfo *codeInfo, 212 const TargetData *td) 213 : NewFunc(newFunc), OldFunc(oldFunc), 214 VMap(valueMap), ModuleLevelChanges(moduleLevelChanges), 215 NameSuffix(nameSuffix), CodeInfo(codeInfo), TD(td) { 216 } 217 218 /// CloneBlock - The specified block is found to be reachable, clone it and 219 /// anything that it can reach. 220 void CloneBlock(const BasicBlock *BB, 221 std::vector<const BasicBlock*> &ToClone); 222 }; 223 } 224 225 /// CloneBlock - The specified block is found to be reachable, clone it and 226 /// anything that it can reach. 227 void PruningFunctionCloner::CloneBlock(const BasicBlock *BB, 228 std::vector<const BasicBlock*> &ToClone){ 229 WeakVH &BBEntry = VMap[BB]; 230 231 // Have we already cloned this block? 232 if (BBEntry) return; 233 234 // Nope, clone it now. 235 BasicBlock *NewBB; 236 BBEntry = NewBB = BasicBlock::Create(BB->getContext()); 237 if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix); 238 239 // It is only legal to clone a function if a block address within that 240 // function is never referenced outside of the function. Given that, we 241 // want to map block addresses from the old function to block addresses in 242 // the clone. (This is different from the generic ValueMapper 243 // implementation, which generates an invalid blockaddress when 244 // cloning a function.) 245 // 246 // Note that we don't need to fix the mapping for unreachable blocks; 247 // the default mapping there is safe. 248 if (BB->hasAddressTaken()) { 249 Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc), 250 const_cast<BasicBlock*>(BB)); 251 VMap[OldBBAddr] = BlockAddress::get(NewFunc, NewBB); 252 } 253 254 255 bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false; 256 257 // Loop over all instructions, and copy them over, DCE'ing as we go. This 258 // loop doesn't include the terminator. 259 for (BasicBlock::const_iterator II = BB->begin(), IE = --BB->end(); 260 II != IE; ++II) { 261 Instruction *NewInst = II->clone(); 262 263 // Eagerly remap operands to the newly cloned instruction, except for PHI 264 // nodes for which we defer processing until we update the CFG. 265 if (!isa<PHINode>(NewInst)) { 266 RemapInstruction(NewInst, VMap, 267 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges); 268 269 // If we can simplify this instruction to some other value, simply add 270 // a mapping to that value rather than inserting a new instruction into 271 // the basic block. 272 if (Value *V = SimplifyInstruction(NewInst, TD)) { 273 // On the off-chance that this simplifies to an instruction in the old 274 // function, map it back into the new function. 275 if (Value *MappedV = VMap.lookup(V)) 276 V = MappedV; 277 278 VMap[II] = V; 279 delete NewInst; 280 continue; 281 } 282 } 283 284 if (II->hasName()) 285 NewInst->setName(II->getName()+NameSuffix); 286 VMap[II] = NewInst; // Add instruction map to value. 287 NewBB->getInstList().push_back(NewInst); 288 hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II)); 289 if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) { 290 if (isa<ConstantInt>(AI->getArraySize())) 291 hasStaticAllocas = true; 292 else 293 hasDynamicAllocas = true; 294 } 295 } 296 297 // Finally, clone over the terminator. 298 const TerminatorInst *OldTI = BB->getTerminator(); 299 bool TerminatorDone = false; 300 if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) { 301 if (BI->isConditional()) { 302 // If the condition was a known constant in the callee... 303 ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition()); 304 // Or is a known constant in the caller... 305 if (Cond == 0) { 306 Value *V = VMap[BI->getCondition()]; 307 Cond = dyn_cast_or_null<ConstantInt>(V); 308 } 309 310 // Constant fold to uncond branch! 311 if (Cond) { 312 BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue()); 313 VMap[OldTI] = BranchInst::Create(Dest, NewBB); 314 ToClone.push_back(Dest); 315 TerminatorDone = true; 316 } 317 } 318 } else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) { 319 // If switching on a value known constant in the caller. 320 ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition()); 321 if (Cond == 0) { // Or known constant after constant prop in the callee... 322 Value *V = VMap[SI->getCondition()]; 323 Cond = dyn_cast_or_null<ConstantInt>(V); 324 } 325 if (Cond) { // Constant fold to uncond branch! 326 SwitchInst::ConstCaseIt Case = SI->findCaseValue(Cond); 327 BasicBlock *Dest = const_cast<BasicBlock*>(Case.getCaseSuccessor()); 328 VMap[OldTI] = BranchInst::Create(Dest, NewBB); 329 ToClone.push_back(Dest); 330 TerminatorDone = true; 331 } 332 } 333 334 if (!TerminatorDone) { 335 Instruction *NewInst = OldTI->clone(); 336 if (OldTI->hasName()) 337 NewInst->setName(OldTI->getName()+NameSuffix); 338 NewBB->getInstList().push_back(NewInst); 339 VMap[OldTI] = NewInst; // Add instruction map to value. 340 341 // Recursively clone any reachable successor blocks. 342 const TerminatorInst *TI = BB->getTerminator(); 343 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) 344 ToClone.push_back(TI->getSuccessor(i)); 345 } 346 347 if (CodeInfo) { 348 CodeInfo->ContainsCalls |= hasCalls; 349 CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas; 350 CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas && 351 BB != &BB->getParent()->front(); 352 } 353 } 354 355 /// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto, 356 /// except that it does some simple constant prop and DCE on the fly. The 357 /// effect of this is to copy significantly less code in cases where (for 358 /// example) a function call with constant arguments is inlined, and those 359 /// constant arguments cause a significant amount of code in the callee to be 360 /// dead. Since this doesn't produce an exact copy of the input, it can't be 361 /// used for things like CloneFunction or CloneModule. 362 void llvm::CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc, 363 ValueToValueMapTy &VMap, 364 bool ModuleLevelChanges, 365 SmallVectorImpl<ReturnInst*> &Returns, 366 const char *NameSuffix, 367 ClonedCodeInfo *CodeInfo, 368 const TargetData *TD, 369 Instruction *TheCall) { 370 assert(NameSuffix && "NameSuffix cannot be null!"); 371 372 #ifndef NDEBUG 373 for (Function::const_arg_iterator II = OldFunc->arg_begin(), 374 E = OldFunc->arg_end(); II != E; ++II) 375 assert(VMap.count(II) && "No mapping from source argument specified!"); 376 #endif 377 378 PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges, 379 NameSuffix, CodeInfo, TD); 380 381 // Clone the entry block, and anything recursively reachable from it. 382 std::vector<const BasicBlock*> CloneWorklist; 383 CloneWorklist.push_back(&OldFunc->getEntryBlock()); 384 while (!CloneWorklist.empty()) { 385 const BasicBlock *BB = CloneWorklist.back(); 386 CloneWorklist.pop_back(); 387 PFC.CloneBlock(BB, CloneWorklist); 388 } 389 390 // Loop over all of the basic blocks in the old function. If the block was 391 // reachable, we have cloned it and the old block is now in the value map: 392 // insert it into the new function in the right order. If not, ignore it. 393 // 394 // Defer PHI resolution until rest of function is resolved. 395 SmallVector<const PHINode*, 16> PHIToResolve; 396 for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end(); 397 BI != BE; ++BI) { 398 Value *V = VMap[BI]; 399 BasicBlock *NewBB = cast_or_null<BasicBlock>(V); 400 if (NewBB == 0) continue; // Dead block. 401 402 // Add the new block to the new function. 403 NewFunc->getBasicBlockList().push_back(NewBB); 404 405 // Handle PHI nodes specially, as we have to remove references to dead 406 // blocks. 407 for (BasicBlock::const_iterator I = BI->begin(), E = BI->end(); I != E; ++I) 408 if (const PHINode *PN = dyn_cast<PHINode>(I)) 409 PHIToResolve.push_back(PN); 410 else 411 break; 412 413 // Finally, remap the terminator instructions, as those can't be remapped 414 // until all BBs are mapped. 415 RemapInstruction(NewBB->getTerminator(), VMap, 416 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges); 417 } 418 419 // Defer PHI resolution until rest of function is resolved, PHI resolution 420 // requires the CFG to be up-to-date. 421 for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) { 422 const PHINode *OPN = PHIToResolve[phino]; 423 unsigned NumPreds = OPN->getNumIncomingValues(); 424 const BasicBlock *OldBB = OPN->getParent(); 425 BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]); 426 427 // Map operands for blocks that are live and remove operands for blocks 428 // that are dead. 429 for (; phino != PHIToResolve.size() && 430 PHIToResolve[phino]->getParent() == OldBB; ++phino) { 431 OPN = PHIToResolve[phino]; 432 PHINode *PN = cast<PHINode>(VMap[OPN]); 433 for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) { 434 Value *V = VMap[PN->getIncomingBlock(pred)]; 435 if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) { 436 Value *InVal = MapValue(PN->getIncomingValue(pred), 437 VMap, 438 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges); 439 assert(InVal && "Unknown input value?"); 440 PN->setIncomingValue(pred, InVal); 441 PN->setIncomingBlock(pred, MappedBlock); 442 } else { 443 PN->removeIncomingValue(pred, false); 444 --pred, --e; // Revisit the next entry. 445 } 446 } 447 } 448 449 // The loop above has removed PHI entries for those blocks that are dead 450 // and has updated others. However, if a block is live (i.e. copied over) 451 // but its terminator has been changed to not go to this block, then our 452 // phi nodes will have invalid entries. Update the PHI nodes in this 453 // case. 454 PHINode *PN = cast<PHINode>(NewBB->begin()); 455 NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB)); 456 if (NumPreds != PN->getNumIncomingValues()) { 457 assert(NumPreds < PN->getNumIncomingValues()); 458 // Count how many times each predecessor comes to this block. 459 std::map<BasicBlock*, unsigned> PredCount; 460 for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB); 461 PI != E; ++PI) 462 --PredCount[*PI]; 463 464 // Figure out how many entries to remove from each PHI. 465 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 466 ++PredCount[PN->getIncomingBlock(i)]; 467 468 // At this point, the excess predecessor entries are positive in the 469 // map. Loop over all of the PHIs and remove excess predecessor 470 // entries. 471 BasicBlock::iterator I = NewBB->begin(); 472 for (; (PN = dyn_cast<PHINode>(I)); ++I) { 473 for (std::map<BasicBlock*, unsigned>::iterator PCI =PredCount.begin(), 474 E = PredCount.end(); PCI != E; ++PCI) { 475 BasicBlock *Pred = PCI->first; 476 for (unsigned NumToRemove = PCI->second; NumToRemove; --NumToRemove) 477 PN->removeIncomingValue(Pred, false); 478 } 479 } 480 } 481 482 // If the loops above have made these phi nodes have 0 or 1 operand, 483 // replace them with undef or the input value. We must do this for 484 // correctness, because 0-operand phis are not valid. 485 PN = cast<PHINode>(NewBB->begin()); 486 if (PN->getNumIncomingValues() == 0) { 487 BasicBlock::iterator I = NewBB->begin(); 488 BasicBlock::const_iterator OldI = OldBB->begin(); 489 while ((PN = dyn_cast<PHINode>(I++))) { 490 Value *NV = UndefValue::get(PN->getType()); 491 PN->replaceAllUsesWith(NV); 492 assert(VMap[OldI] == PN && "VMap mismatch"); 493 VMap[OldI] = NV; 494 PN->eraseFromParent(); 495 ++OldI; 496 } 497 } 498 } 499 500 // Make a second pass over the PHINodes now that all of them have been 501 // remapped into the new function, simplifying the PHINode and performing any 502 // recursive simplifications exposed. This will transparently update the 503 // WeakVH in the VMap. Notably, we rely on that so that if we coalesce 504 // two PHINodes, the iteration over the old PHIs remains valid, and the 505 // mapping will just map us to the new node (which may not even be a PHI 506 // node). 507 for (unsigned Idx = 0, Size = PHIToResolve.size(); Idx != Size; ++Idx) 508 if (PHINode *PN = dyn_cast<PHINode>(VMap[PHIToResolve[Idx]])) 509 recursivelySimplifyInstruction(PN, TD); 510 511 // Now that the inlined function body has been fully constructed, go through 512 // and zap unconditional fall-through branches. This happen all the time when 513 // specializing code: code specialization turns conditional branches into 514 // uncond branches, and this code folds them. 515 Function::iterator Begin = cast<BasicBlock>(VMap[&OldFunc->getEntryBlock()]); 516 Function::iterator I = Begin; 517 while (I != NewFunc->end()) { 518 // Check if this block has become dead during inlining or other 519 // simplifications. Note that the first block will appear dead, as it has 520 // not yet been wired up properly. 521 if (I != Begin && (pred_begin(I) == pred_end(I) || 522 I->getSinglePredecessor() == I)) { 523 BasicBlock *DeadBB = I++; 524 DeleteDeadBlock(DeadBB); 525 continue; 526 } 527 528 // We need to simplify conditional branches and switches with a constant 529 // operand. We try to prune these out when cloning, but if the 530 // simplification required looking through PHI nodes, those are only 531 // available after forming the full basic block. That may leave some here, 532 // and we still want to prune the dead code as early as possible. 533 ConstantFoldTerminator(I); 534 535 BranchInst *BI = dyn_cast<BranchInst>(I->getTerminator()); 536 if (!BI || BI->isConditional()) { ++I; continue; } 537 538 BasicBlock *Dest = BI->getSuccessor(0); 539 if (!Dest->getSinglePredecessor()) { 540 ++I; continue; 541 } 542 543 // We shouldn't be able to get single-entry PHI nodes here, as instsimplify 544 // above should have zapped all of them.. 545 assert(!isa<PHINode>(Dest->begin())); 546 547 // We know all single-entry PHI nodes in the inlined function have been 548 // removed, so we just need to splice the blocks. 549 BI->eraseFromParent(); 550 551 // Make all PHI nodes that referred to Dest now refer to I as their source. 552 Dest->replaceAllUsesWith(I); 553 554 // Move all the instructions in the succ to the pred. 555 I->getInstList().splice(I->end(), Dest->getInstList()); 556 557 // Remove the dest block. 558 Dest->eraseFromParent(); 559 560 // Do not increment I, iteratively merge all things this block branches to. 561 } 562 563 // Make a final pass over the basic blocks from theh old function to gather 564 // any return instructions which survived folding. We have to do this here 565 // because we can iteratively remove and merge returns above. 566 for (Function::iterator I = cast<BasicBlock>(VMap[&OldFunc->getEntryBlock()]), 567 E = NewFunc->end(); 568 I != E; ++I) 569 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) 570 Returns.push_back(RI); 571 } 572