ArgumentPromotion.cpp revision 081ce940e7351e90fff829320b7dc6738a6b3815
1//===-- ArgumentPromotion.cpp - Promote by-reference arguments ------------===// 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 pass promotes "by reference" arguments to be "by value" arguments. In 11// practice, this means looking for internal functions that have pointer 12// arguments. If it can prove, through the use of alias analysis, that an 13// argument is *only* loaded, then it can pass the value into the function 14// instead of the address of the value. This can cause recursive simplification 15// of code and lead to the elimination of allocas (especially in C++ template 16// code like the STL). 17// 18// This pass also handles aggregate arguments that are passed into a function, 19// scalarizing them if the elements of the aggregate are only loaded. Note that 20// it refuses to scalarize aggregates which would require passing in more than 21// three operands to the function, because passing thousands of operands for a 22// large array or structure is unprofitable! 23// 24// Note that this transformation could also be done for arguments that are only 25// stored to (returning the value instead), but does not currently. This case 26// would be best handled when and if LLVM begins supporting multiple return 27// values from functions. 28// 29//===----------------------------------------------------------------------===// 30 31#define DEBUG_TYPE "argpromotion" 32#include "llvm/Transforms/IPO.h" 33#include "llvm/Constants.h" 34#include "llvm/DerivedTypes.h" 35#include "llvm/Module.h" 36#include "llvm/CallGraphSCCPass.h" 37#include "llvm/Instructions.h" 38#include "llvm/ParameterAttributes.h" 39#include "llvm/Analysis/AliasAnalysis.h" 40#include "llvm/Analysis/CallGraph.h" 41#include "llvm/Target/TargetData.h" 42#include "llvm/Support/CallSite.h" 43#include "llvm/Support/CFG.h" 44#include "llvm/Support/Debug.h" 45#include "llvm/ADT/DepthFirstIterator.h" 46#include "llvm/ADT/Statistic.h" 47#include "llvm/ADT/StringExtras.h" 48#include "llvm/Support/Compiler.h" 49#include <set> 50using namespace llvm; 51 52STATISTIC(NumArgumentsPromoted , "Number of pointer arguments promoted"); 53STATISTIC(NumAggregatesPromoted, "Number of aggregate arguments promoted"); 54STATISTIC(NumArgumentsDead , "Number of dead pointer args eliminated"); 55 56namespace { 57 /// ArgPromotion - The 'by reference' to 'by value' argument promotion pass. 58 /// 59 struct VISIBILITY_HIDDEN ArgPromotion : public CallGraphSCCPass { 60 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 61 AU.addRequired<AliasAnalysis>(); 62 AU.addRequired<TargetData>(); 63 CallGraphSCCPass::getAnalysisUsage(AU); 64 } 65 66 virtual bool runOnSCC(const std::vector<CallGraphNode *> &SCC); 67 static char ID; // Pass identification, replacement for typeid 68 ArgPromotion() : CallGraphSCCPass((intptr_t)&ID) {} 69 70 private: 71 bool PromoteArguments(CallGraphNode *CGN); 72 bool isSafeToPromoteArgument(Argument *Arg) const; 73 Function *DoPromotion(Function *F, std::vector<Argument*> &ArgsToPromote); 74 }; 75 76 char ArgPromotion::ID = 0; 77 RegisterPass<ArgPromotion> X("argpromotion", 78 "Promote 'by reference' arguments to scalars"); 79} 80 81Pass *llvm::createArgumentPromotionPass() { 82 return new ArgPromotion(); 83} 84 85bool ArgPromotion::runOnSCC(const std::vector<CallGraphNode *> &SCC) { 86 bool Changed = false, LocalChange; 87 88 do { // Iterate until we stop promoting from this SCC. 89 LocalChange = false; 90 // Attempt to promote arguments from all functions in this SCC. 91 for (unsigned i = 0, e = SCC.size(); i != e; ++i) 92 LocalChange |= PromoteArguments(SCC[i]); 93 Changed |= LocalChange; // Remember that we changed something. 94 } while (LocalChange); 95 96 return Changed; 97} 98 99/// PromoteArguments - This method checks the specified function to see if there 100/// are any promotable arguments and if it is safe to promote the function (for 101/// example, all callers are direct). If safe to promote some arguments, it 102/// calls the DoPromotion method. 103/// 104bool ArgPromotion::PromoteArguments(CallGraphNode *CGN) { 105 Function *F = CGN->getFunction(); 106 107 // Make sure that it is local to this module. 108 if (!F || !F->hasInternalLinkage()) return false; 109 110 // First check: see if there are any pointer arguments! If not, quick exit. 111 std::vector<Argument*> PointerArgs; 112 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; ++I) 113 if (isa<PointerType>(I->getType())) 114 PointerArgs.push_back(I); 115 if (PointerArgs.empty()) return false; 116 117 // Second check: make sure that all callers are direct callers. We can't 118 // transform functions that have indirect callers. 119 for (Value::use_iterator UI = F->use_begin(), E = F->use_end(); 120 UI != E; ++UI) { 121 CallSite CS = CallSite::get(*UI); 122 if (!CS.getInstruction()) // "Taking the address" of the function 123 return false; 124 125 // Ensure that this call site is CALLING the function, not passing it as 126 // an argument. 127 for (CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end(); 128 AI != E; ++AI) 129 if (*AI == F) return false; // Passing the function address in! 130 } 131 132 // Check to see which arguments are promotable. If an argument is not 133 // promotable, remove it from the PointerArgs vector. 134 for (unsigned i = 0; i != PointerArgs.size(); ++i) 135 if (!isSafeToPromoteArgument(PointerArgs[i])) { 136 std::swap(PointerArgs[i--], PointerArgs.back()); 137 PointerArgs.pop_back(); 138 } 139 140 // No promotable pointer arguments. 141 if (PointerArgs.empty()) return false; 142 143 // Okay, promote all of the arguments and rewrite the callees! 144 Function *NewF = DoPromotion(F, PointerArgs); 145 146 // Update the call graph to know that the function has been transformed. 147 getAnalysis<CallGraph>().changeFunction(F, NewF); 148 return true; 149} 150 151/// IsAlwaysValidPointer - Return true if the specified pointer is always legal 152/// to load. 153static bool IsAlwaysValidPointer(Value *V) { 154 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true; 155 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) 156 return IsAlwaysValidPointer(GEP->getOperand(0)); 157 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) 158 if (CE->getOpcode() == Instruction::GetElementPtr) 159 return IsAlwaysValidPointer(CE->getOperand(0)); 160 161 return false; 162} 163 164/// AllCalleesPassInValidPointerForArgument - Return true if we can prove that 165/// all callees pass in a valid pointer for the specified function argument. 166static bool AllCalleesPassInValidPointerForArgument(Argument *Arg) { 167 Function *Callee = Arg->getParent(); 168 169 unsigned ArgNo = std::distance(Callee->arg_begin(), 170 Function::arg_iterator(Arg)); 171 172 // Look at all call sites of the function. At this pointer we know we only 173 // have direct callees. 174 for (Value::use_iterator UI = Callee->use_begin(), E = Callee->use_end(); 175 UI != E; ++UI) { 176 CallSite CS = CallSite::get(*UI); 177 assert(CS.getInstruction() && "Should only have direct calls!"); 178 179 if (!IsAlwaysValidPointer(CS.getArgument(ArgNo))) 180 return false; 181 } 182 return true; 183} 184 185 186/// isSafeToPromoteArgument - As you might guess from the name of this method, 187/// it checks to see if it is both safe and useful to promote the argument. 188/// This method limits promotion of aggregates to only promote up to three 189/// elements of the aggregate in order to avoid exploding the number of 190/// arguments passed in. 191bool ArgPromotion::isSafeToPromoteArgument(Argument *Arg) const { 192 // We can only promote this argument if all of the uses are loads, or are GEP 193 // instructions (with constant indices) that are subsequently loaded. 194 bool HasLoadInEntryBlock = false; 195 BasicBlock *EntryBlock = Arg->getParent()->begin(); 196 std::vector<LoadInst*> Loads; 197 std::vector<std::vector<ConstantInt*> > GEPIndices; 198 for (Value::use_iterator UI = Arg->use_begin(), E = Arg->use_end(); 199 UI != E; ++UI) 200 if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) { 201 if (LI->isVolatile()) return false; // Don't hack volatile loads 202 Loads.push_back(LI); 203 HasLoadInEntryBlock |= LI->getParent() == EntryBlock; 204 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(*UI)) { 205 if (GEP->use_empty()) { 206 // Dead GEP's cause trouble later. Just remove them if we run into 207 // them. 208 getAnalysis<AliasAnalysis>().deleteValue(GEP); 209 GEP->getParent()->getInstList().erase(GEP); 210 return isSafeToPromoteArgument(Arg); 211 } 212 // Ensure that all of the indices are constants. 213 std::vector<ConstantInt*> Operands; 214 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i) 215 if (ConstantInt *C = dyn_cast<ConstantInt>(GEP->getOperand(i))) 216 Operands.push_back(C); 217 else 218 return false; // Not a constant operand GEP! 219 220 // Ensure that the only users of the GEP are load instructions. 221 for (Value::use_iterator UI = GEP->use_begin(), E = GEP->use_end(); 222 UI != E; ++UI) 223 if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) { 224 if (LI->isVolatile()) return false; // Don't hack volatile loads 225 Loads.push_back(LI); 226 HasLoadInEntryBlock |= LI->getParent() == EntryBlock; 227 } else { 228 return false; 229 } 230 231 // See if there is already a GEP with these indices. If not, check to 232 // make sure that we aren't promoting too many elements. If so, nothing 233 // to do. 234 if (std::find(GEPIndices.begin(), GEPIndices.end(), Operands) == 235 GEPIndices.end()) { 236 if (GEPIndices.size() == 3) { 237 DOUT << "argpromotion disable promoting argument '" 238 << Arg->getName() << "' because it would require adding more " 239 << "than 3 arguments to the function.\n"; 240 // We limit aggregate promotion to only promoting up to three elements 241 // of the aggregate. 242 return false; 243 } 244 GEPIndices.push_back(Operands); 245 } 246 } else { 247 return false; // Not a load or a GEP. 248 } 249 250 if (Loads.empty()) return true; // No users, this is a dead argument. 251 252 // If we decide that we want to promote this argument, the value is going to 253 // be unconditionally loaded in all callees. This is only safe to do if the 254 // pointer was going to be unconditionally loaded anyway (i.e. there is a load 255 // of the pointer in the entry block of the function) or if we can prove that 256 // all pointers passed in are always to legal locations (for example, no null 257 // pointers are passed in, no pointers to free'd memory, etc). 258 if (!HasLoadInEntryBlock && !AllCalleesPassInValidPointerForArgument(Arg)) 259 return false; // Cannot prove that this is safe!! 260 261 // Okay, now we know that the argument is only used by load instructions and 262 // it is safe to unconditionally load the pointer. Use alias analysis to 263 // check to see if the pointer is guaranteed to not be modified from entry of 264 // the function to each of the load instructions. 265 266 // Because there could be several/many load instructions, remember which 267 // blocks we know to be transparent to the load. 268 std::set<BasicBlock*> TranspBlocks; 269 270 AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 271 TargetData &TD = getAnalysis<TargetData>(); 272 273 for (unsigned i = 0, e = Loads.size(); i != e; ++i) { 274 // Check to see if the load is invalidated from the start of the block to 275 // the load itself. 276 LoadInst *Load = Loads[i]; 277 BasicBlock *BB = Load->getParent(); 278 279 const PointerType *LoadTy = 280 cast<PointerType>(Load->getOperand(0)->getType()); 281 unsigned LoadSize = (unsigned)TD.getTypeStoreSize(LoadTy->getElementType()); 282 283 if (AA.canInstructionRangeModify(BB->front(), *Load, Arg, LoadSize)) 284 return false; // Pointer is invalidated! 285 286 // Now check every path from the entry block to the load for transparency. 287 // To do this, we perform a depth first search on the inverse CFG from the 288 // loading block. 289 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 290 for (idf_ext_iterator<BasicBlock*> I = idf_ext_begin(*PI, TranspBlocks), 291 E = idf_ext_end(*PI, TranspBlocks); I != E; ++I) 292 if (AA.canBasicBlockModify(**I, Arg, LoadSize)) 293 return false; 294 } 295 296 // If the path from the entry of the function to each load is free of 297 // instructions that potentially invalidate the load, we can make the 298 // transformation! 299 return true; 300} 301 302namespace { 303 /// GEPIdxComparator - Provide a strong ordering for GEP indices. All Value* 304 /// elements are instances of ConstantInt. 305 /// 306 struct GEPIdxComparator { 307 bool operator()(const std::vector<Value*> &LHS, 308 const std::vector<Value*> &RHS) const { 309 unsigned idx = 0; 310 for (; idx < LHS.size() && idx < RHS.size(); ++idx) { 311 if (LHS[idx] != RHS[idx]) { 312 return cast<ConstantInt>(LHS[idx])->getZExtValue() < 313 cast<ConstantInt>(RHS[idx])->getZExtValue(); 314 } 315 } 316 317 // Return less than if we ran out of stuff in LHS and we didn't run out of 318 // stuff in RHS. 319 return idx == LHS.size() && idx != RHS.size(); 320 } 321 }; 322} 323 324 325/// DoPromotion - This method actually performs the promotion of the specified 326/// arguments, and returns the new function. At this point, we know that it's 327/// safe to do so. 328Function *ArgPromotion::DoPromotion(Function *F, 329 std::vector<Argument*> &Args2Prom) { 330 std::set<Argument*> ArgsToPromote(Args2Prom.begin(), Args2Prom.end()); 331 332 // Start by computing a new prototype for the function, which is the same as 333 // the old function, but has modified arguments. 334 const FunctionType *FTy = F->getFunctionType(); 335 std::vector<const Type*> Params; 336 337 typedef std::set<std::vector<Value*>, GEPIdxComparator> ScalarizeTable; 338 339 // ScalarizedElements - If we are promoting a pointer that has elements 340 // accessed out of it, keep track of which elements are accessed so that we 341 // can add one argument for each. 342 // 343 // Arguments that are directly loaded will have a zero element value here, to 344 // handle cases where there are both a direct load and GEP accesses. 345 // 346 std::map<Argument*, ScalarizeTable> ScalarizedElements; 347 348 // OriginalLoads - Keep track of a representative load instruction from the 349 // original function so that we can tell the alias analysis implementation 350 // what the new GEP/Load instructions we are inserting look like. 351 std::map<std::vector<Value*>, LoadInst*> OriginalLoads; 352 353 // ParamAttrs - Keep track of the parameter attributes for the arguments 354 // that we are *not* promoting. For the ones that we do promote, the parameter 355 // attributes are lost 356 ParamAttrsVector ParamAttrsVec; 357 const ParamAttrsList *PAL = F->getParamAttrs(); 358 359 unsigned index = 1; 360 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; 361 ++I, ++index) 362 if (!ArgsToPromote.count(I)) { 363 Params.push_back(I->getType()); 364 if (PAL) { 365 unsigned attrs = PAL->getParamAttrs(index); 366 if (attrs) 367 ParamAttrsVec.push_back(ParamAttrsWithIndex::get(Params.size(), 368 attrs)); 369 } 370 } else if (I->use_empty()) { 371 ++NumArgumentsDead; 372 } else { 373 // Okay, this is being promoted. Check to see if there are any GEP uses 374 // of the argument. 375 ScalarizeTable &ArgIndices = ScalarizedElements[I]; 376 for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E; 377 ++UI) { 378 Instruction *User = cast<Instruction>(*UI); 379 assert(isa<LoadInst>(User) || isa<GetElementPtrInst>(User)); 380 std::vector<Value*> Indices(User->op_begin()+1, User->op_end()); 381 ArgIndices.insert(Indices); 382 LoadInst *OrigLoad; 383 if (LoadInst *L = dyn_cast<LoadInst>(User)) 384 OrigLoad = L; 385 else 386 OrigLoad = cast<LoadInst>(User->use_back()); 387 OriginalLoads[Indices] = OrigLoad; 388 } 389 390 // Add a parameter to the function for each element passed in. 391 for (ScalarizeTable::iterator SI = ArgIndices.begin(), 392 E = ArgIndices.end(); SI != E; ++SI) 393 Params.push_back(GetElementPtrInst::getIndexedType(I->getType(), 394 SI->begin(), 395 SI->end())); 396 397 if (ArgIndices.size() == 1 && ArgIndices.begin()->empty()) 398 ++NumArgumentsPromoted; 399 else 400 ++NumAggregatesPromoted; 401 } 402 403 const Type *RetTy = FTy->getReturnType(); 404 405 // Recompute the parameter attributes list based on the new arguments for 406 // the function. 407 if (ParamAttrsVec.empty()) 408 PAL = 0; 409 else 410 PAL = ParamAttrsList::get(ParamAttrsVec); 411 412 // Work around LLVM bug PR56: the CWriter cannot emit varargs functions which 413 // have zero fixed arguments. 414 bool ExtraArgHack = false; 415 if (Params.empty() && FTy->isVarArg()) { 416 ExtraArgHack = true; 417 Params.push_back(Type::Int32Ty); 418 } 419 420 // Construct the new function type using the new arguments. 421 FunctionType *NFTy = FunctionType::get(RetTy, Params, FTy->isVarArg()); 422 423 // Create the new function body and insert it into the module... 424 Function *NF = new Function(NFTy, F->getLinkage(), F->getName()); 425 NF->setCallingConv(F->getCallingConv()); 426 NF->setParamAttrs(PAL); 427 if (F->hasCollector()) 428 NF->setCollector(F->getCollector()); 429 F->getParent()->getFunctionList().insert(F, NF); 430 431 // Get the alias analysis information that we need to update to reflect our 432 // changes. 433 AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 434 435 // Loop over all of the callers of the function, transforming the call sites 436 // to pass in the loaded pointers. 437 // 438 std::vector<Value*> Args; 439 while (!F->use_empty()) { 440 CallSite CS = CallSite::get(F->use_back()); 441 Instruction *Call = CS.getInstruction(); 442 443 // Loop over the operands, inserting GEP and loads in the caller as 444 // appropriate. 445 CallSite::arg_iterator AI = CS.arg_begin(); 446 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); 447 I != E; ++I, ++AI) 448 if (!ArgsToPromote.count(I)) 449 Args.push_back(*AI); // Unmodified argument 450 else if (!I->use_empty()) { 451 // Non-dead argument: insert GEPs and loads as appropriate. 452 ScalarizeTable &ArgIndices = ScalarizedElements[I]; 453 for (ScalarizeTable::iterator SI = ArgIndices.begin(), 454 E = ArgIndices.end(); SI != E; ++SI) { 455 Value *V = *AI; 456 LoadInst *OrigLoad = OriginalLoads[*SI]; 457 if (!SI->empty()) { 458 V = new GetElementPtrInst(V, SI->begin(), SI->end(), 459 V->getName()+".idx", Call); 460 AA.copyValue(OrigLoad->getOperand(0), V); 461 } 462 Args.push_back(new LoadInst(V, V->getName()+".val", Call)); 463 AA.copyValue(OrigLoad, Args.back()); 464 } 465 } 466 467 if (ExtraArgHack) 468 Args.push_back(Constant::getNullValue(Type::Int32Ty)); 469 470 // Push any varargs arguments on the list 471 for (; AI != CS.arg_end(); ++AI) 472 Args.push_back(*AI); 473 474 Instruction *New; 475 if (InvokeInst *II = dyn_cast<InvokeInst>(Call)) { 476 New = new InvokeInst(NF, II->getNormalDest(), II->getUnwindDest(), 477 Args.begin(), Args.end(), "", Call); 478 cast<InvokeInst>(New)->setCallingConv(CS.getCallingConv()); 479 cast<InvokeInst>(New)->setParamAttrs(PAL); 480 } else { 481 New = new CallInst(NF, Args.begin(), Args.end(), "", Call); 482 cast<CallInst>(New)->setCallingConv(CS.getCallingConv()); 483 cast<CallInst>(New)->setParamAttrs(PAL); 484 if (cast<CallInst>(Call)->isTailCall()) 485 cast<CallInst>(New)->setTailCall(); 486 } 487 Args.clear(); 488 489 // Update the alias analysis implementation to know that we are replacing 490 // the old call with a new one. 491 AA.replaceWithNewValue(Call, New); 492 493 if (!Call->use_empty()) { 494 Call->replaceAllUsesWith(New); 495 New->takeName(Call); 496 } 497 498 // Finally, remove the old call from the program, reducing the use-count of 499 // F. 500 Call->getParent()->getInstList().erase(Call); 501 } 502 503 // Since we have now created the new function, splice the body of the old 504 // function right into the new function, leaving the old rotting hulk of the 505 // function empty. 506 NF->getBasicBlockList().splice(NF->begin(), F->getBasicBlockList()); 507 508 // Loop over the argument list, transfering uses of the old arguments over to 509 // the new arguments, also transfering over the names as well. 510 // 511 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(), 512 I2 = NF->arg_begin(); I != E; ++I) 513 if (!ArgsToPromote.count(I)) { 514 // If this is an unmodified argument, move the name and users over to the 515 // new version. 516 I->replaceAllUsesWith(I2); 517 I2->takeName(I); 518 AA.replaceWithNewValue(I, I2); 519 ++I2; 520 } else if (I->use_empty()) { 521 AA.deleteValue(I); 522 } else { 523 // Otherwise, if we promoted this argument, then all users are load 524 // instructions, and all loads should be using the new argument that we 525 // added. 526 ScalarizeTable &ArgIndices = ScalarizedElements[I]; 527 528 while (!I->use_empty()) { 529 if (LoadInst *LI = dyn_cast<LoadInst>(I->use_back())) { 530 assert(ArgIndices.begin()->empty() && 531 "Load element should sort to front!"); 532 I2->setName(I->getName()+".val"); 533 LI->replaceAllUsesWith(I2); 534 AA.replaceWithNewValue(LI, I2); 535 LI->getParent()->getInstList().erase(LI); 536 DOUT << "*** Promoted load of argument '" << I->getName() 537 << "' in function '" << F->getName() << "'\n"; 538 } else { 539 GetElementPtrInst *GEP = cast<GetElementPtrInst>(I->use_back()); 540 std::vector<Value*> Operands(GEP->op_begin()+1, GEP->op_end()); 541 542 Function::arg_iterator TheArg = I2; 543 for (ScalarizeTable::iterator It = ArgIndices.begin(); 544 *It != Operands; ++It, ++TheArg) { 545 assert(It != ArgIndices.end() && "GEP not handled??"); 546 } 547 548 std::string NewName = I->getName(); 549 for (unsigned i = 0, e = Operands.size(); i != e; ++i) 550 if (ConstantInt *CI = dyn_cast<ConstantInt>(Operands[i])) 551 NewName += "." + CI->getValue().toStringUnsigned(10); 552 else 553 NewName += ".x"; 554 TheArg->setName(NewName+".val"); 555 556 DOUT << "*** Promoted agg argument '" << TheArg->getName() 557 << "' of function '" << F->getName() << "'\n"; 558 559 // All of the uses must be load instructions. Replace them all with 560 // the argument specified by ArgNo. 561 while (!GEP->use_empty()) { 562 LoadInst *L = cast<LoadInst>(GEP->use_back()); 563 L->replaceAllUsesWith(TheArg); 564 AA.replaceWithNewValue(L, TheArg); 565 L->getParent()->getInstList().erase(L); 566 } 567 AA.deleteValue(GEP); 568 GEP->getParent()->getInstList().erase(GEP); 569 } 570 } 571 572 // Increment I2 past all of the arguments added for this promoted pointer. 573 for (unsigned i = 0, e = ArgIndices.size(); i != e; ++i) 574 ++I2; 575 } 576 577 // Notify the alias analysis implementation that we inserted a new argument. 578 if (ExtraArgHack) 579 AA.copyValue(Constant::getNullValue(Type::Int32Ty), NF->arg_begin()); 580 581 582 // Tell the alias analysis that the old function is about to disappear. 583 AA.replaceWithNewValue(F, NF); 584 585 // Now that the old function is dead, delete it. 586 F->getParent()->getFunctionList().erase(F); 587 return NF; 588} 589