ArgumentPromotion.cpp revision e027efa21816dbd2350d137fdfa181c24cbe8c49
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, bool isByVal) const; 73 Function *DoPromotion(Function *F, 74 SmallPtrSet<Argument*, 8> &ArgsToPromote); 75 }; 76 77 char ArgPromotion::ID = 0; 78 RegisterPass<ArgPromotion> X("argpromotion", 79 "Promote 'by reference' arguments to scalars"); 80} 81 82Pass *llvm::createArgumentPromotionPass() { 83 return new ArgPromotion(); 84} 85 86bool ArgPromotion::runOnSCC(const std::vector<CallGraphNode *> &SCC) { 87 bool Changed = false, LocalChange; 88 89 do { // Iterate until we stop promoting from this SCC. 90 LocalChange = false; 91 // Attempt to promote arguments from all functions in this SCC. 92 for (unsigned i = 0, e = SCC.size(); i != e; ++i) 93 LocalChange |= PromoteArguments(SCC[i]); 94 Changed |= LocalChange; // Remember that we changed something. 95 } while (LocalChange); 96 97 return Changed; 98} 99 100/// PromoteArguments - This method checks the specified function to see if there 101/// are any promotable arguments and if it is safe to promote the function (for 102/// example, all callers are direct). If safe to promote some arguments, it 103/// calls the DoPromotion method. 104/// 105bool ArgPromotion::PromoteArguments(CallGraphNode *CGN) { 106 Function *F = CGN->getFunction(); 107 108 // Make sure that it is local to this module. 109 if (!F || !F->hasInternalLinkage()) return false; 110 111 // First check: see if there are any pointer arguments! If not, quick exit. 112 SmallVector<std::pair<Argument*, unsigned>, 16> PointerArgs; 113 unsigned ArgNo = 0; 114 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); 115 I != E; ++I, ++ArgNo) 116 if (isa<PointerType>(I->getType())) 117 PointerArgs.push_back(std::pair<Argument*, unsigned>(I, ArgNo)); 118 if (PointerArgs.empty()) return false; 119 120 // Second check: make sure that all callers are direct callers. We can't 121 // transform functions that have indirect callers. 122 for (Value::use_iterator UI = F->use_begin(), E = F->use_end(); 123 UI != E; ++UI) { 124 CallSite CS = CallSite::get(*UI); 125 if (!CS.getInstruction()) // "Taking the address" of the function 126 return false; 127 128 // Ensure that this call site is CALLING the function, not passing it as 129 // an argument. 130 if (UI.getOperandNo() != 0) 131 return false; 132 } 133 134 // Check to see which arguments are promotable. If an argument is promotable, 135 // add it to ArgsToPromote. 136 SmallPtrSet<Argument*, 8> ArgsToPromote; 137 for (unsigned i = 0; i != PointerArgs.size(); ++i) { 138 bool isByVal = F->paramHasAttr(PointerArgs[i].second, ParamAttr::ByVal); 139 if (isSafeToPromoteArgument(PointerArgs[i].first, isByVal)) 140 ArgsToPromote.insert(PointerArgs[i].first); 141 } 142 143 // No promotable pointer arguments. 144 if (ArgsToPromote.empty()) return false; 145 146 Function *NewF = DoPromotion(F, ArgsToPromote); 147 148 // Update the call graph to know that the function has been transformed. 149 getAnalysis<CallGraph>().changeFunction(F, NewF); 150 return true; 151} 152 153/// IsAlwaysValidPointer - Return true if the specified pointer is always legal 154/// to load. 155static bool IsAlwaysValidPointer(Value *V) { 156 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true; 157 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) 158 return IsAlwaysValidPointer(GEP->getOperand(0)); 159 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) 160 if (CE->getOpcode() == Instruction::GetElementPtr) 161 return IsAlwaysValidPointer(CE->getOperand(0)); 162 163 return false; 164} 165 166/// AllCalleesPassInValidPointerForArgument - Return true if we can prove that 167/// all callees pass in a valid pointer for the specified function argument. 168static bool AllCalleesPassInValidPointerForArgument(Argument *Arg) { 169 Function *Callee = Arg->getParent(); 170 171 unsigned ArgNo = std::distance(Callee->arg_begin(), 172 Function::arg_iterator(Arg)); 173 174 // Look at all call sites of the function. At this pointer we know we only 175 // have direct callees. 176 for (Value::use_iterator UI = Callee->use_begin(), E = Callee->use_end(); 177 UI != E; ++UI) { 178 CallSite CS = CallSite::get(*UI); 179 assert(CS.getInstruction() && "Should only have direct calls!"); 180 181 if (!IsAlwaysValidPointer(CS.getArgument(ArgNo))) 182 return false; 183 } 184 return true; 185} 186 187 188/// isSafeToPromoteArgument - As you might guess from the name of this method, 189/// it checks to see if it is both safe and useful to promote the argument. 190/// This method limits promotion of aggregates to only promote up to three 191/// elements of the aggregate in order to avoid exploding the number of 192/// arguments passed in. 193bool ArgPromotion::isSafeToPromoteArgument(Argument *Arg, bool isByVal) const { 194 // We can only promote this argument if all of the uses are loads, or are GEP 195 // instructions (with constant indices) that are subsequently loaded. 196 197 // We can also only promote the load if we can guarantee that it will happen. 198 // Promoting a load causes the load to be unconditionally executed in the 199 // caller, so we can't turn a conditional load into an unconditional load in 200 // general. 201 bool SafeToUnconditionallyLoad = false; 202 if (isByVal) // ByVal arguments are always safe to load from. 203 SafeToUnconditionallyLoad = true; 204 205 BasicBlock *EntryBlock = Arg->getParent()->begin(); 206 SmallVector<LoadInst*, 16> Loads; 207 std::vector<SmallVector<ConstantInt*, 8> > GEPIndices; 208 for (Value::use_iterator UI = Arg->use_begin(), E = Arg->use_end(); 209 UI != E; ++UI) 210 if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) { 211 if (LI->isVolatile()) return false; // Don't hack volatile loads 212 Loads.push_back(LI); 213 214 // If this load occurs in the entry block, then the pointer is 215 // unconditionally loaded. 216 SafeToUnconditionallyLoad |= LI->getParent() == EntryBlock; 217 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(*UI)) { 218 if (GEP->use_empty()) { 219 // Dead GEP's cause trouble later. Just remove them if we run into 220 // them. 221 getAnalysis<AliasAnalysis>().deleteValue(GEP); 222 GEP->eraseFromParent(); 223 return isSafeToPromoteArgument(Arg, isByVal); 224 } 225 // Ensure that all of the indices are constants. 226 SmallVector<ConstantInt*, 8> Operands; 227 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i) 228 if (ConstantInt *C = dyn_cast<ConstantInt>(GEP->getOperand(i))) 229 Operands.push_back(C); 230 else 231 return false; // Not a constant operand GEP! 232 233 // Ensure that the only users of the GEP are load instructions. 234 for (Value::use_iterator UI = GEP->use_begin(), E = GEP->use_end(); 235 UI != E; ++UI) 236 if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) { 237 if (LI->isVolatile()) return false; // Don't hack volatile loads 238 Loads.push_back(LI); 239 240 // If this load occurs in the entry block, then the pointer is 241 // unconditionally loaded. 242 SafeToUnconditionallyLoad |= LI->getParent() == EntryBlock; 243 } else { 244 return false; 245 } 246 247 // See if there is already a GEP with these indices. If not, check to 248 // make sure that we aren't promoting too many elements. If so, nothing 249 // to do. 250 if (std::find(GEPIndices.begin(), GEPIndices.end(), Operands) == 251 GEPIndices.end()) { 252 if (GEPIndices.size() == 3) { 253 DOUT << "argpromotion disable promoting argument '" 254 << Arg->getName() << "' because it would require adding more " 255 << "than 3 arguments to the function.\n"; 256 // We limit aggregate promotion to only promoting up to three elements 257 // of the aggregate. 258 return false; 259 } 260 GEPIndices.push_back(Operands); 261 } 262 } else { 263 return false; // Not a load or a GEP. 264 } 265 266 if (Loads.empty()) return true; // No users, this is a dead argument. 267 268 // If we decide that we want to promote this argument, the value is going to 269 // be unconditionally loaded in all callees. This is only safe to do if the 270 // pointer was going to be unconditionally loaded anyway (i.e. there is a load 271 // of the pointer in the entry block of the function) or if we can prove that 272 // all pointers passed in are always to legal locations (for example, no null 273 // pointers are passed in, no pointers to free'd memory, etc). 274 if (!SafeToUnconditionallyLoad && 275 !AllCalleesPassInValidPointerForArgument(Arg)) 276 return false; // Cannot prove that this is safe!! 277 278 // Okay, now we know that the argument is only used by load instructions and 279 // it is safe to unconditionally load the pointer. Use alias analysis to 280 // check to see if the pointer is guaranteed to not be modified from entry of 281 // the function to each of the load instructions. 282 283 // Because there could be several/many load instructions, remember which 284 // blocks we know to be transparent to the load. 285 SmallPtrSet<BasicBlock*, 16> TranspBlocks; 286 287 AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 288 TargetData &TD = getAnalysis<TargetData>(); 289 290 for (unsigned i = 0, e = Loads.size(); i != e; ++i) { 291 // Check to see if the load is invalidated from the start of the block to 292 // the load itself. 293 LoadInst *Load = Loads[i]; 294 BasicBlock *BB = Load->getParent(); 295 296 const PointerType *LoadTy = 297 cast<PointerType>(Load->getOperand(0)->getType()); 298 unsigned LoadSize = (unsigned)TD.getTypeStoreSize(LoadTy->getElementType()); 299 300 if (AA.canInstructionRangeModify(BB->front(), *Load, Arg, LoadSize)) 301 return false; // Pointer is invalidated! 302 303 // Now check every path from the entry block to the load for transparency. 304 // To do this, we perform a depth first search on the inverse CFG from the 305 // loading block. 306 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 307 for (idf_ext_iterator<BasicBlock*, SmallPtrSet<BasicBlock*, 16> > 308 I = idf_ext_begin(*PI, TranspBlocks), 309 E = idf_ext_end(*PI, TranspBlocks); I != E; ++I) 310 if (AA.canBasicBlockModify(**I, Arg, LoadSize)) 311 return false; 312 } 313 314 // If the path from the entry of the function to each load is free of 315 // instructions that potentially invalidate the load, we can make the 316 // transformation! 317 return true; 318} 319 320namespace { 321 /// GEPIdxComparator - Provide a strong ordering for GEP indices. All Value* 322 /// elements are instances of ConstantInt. 323 /// 324 struct GEPIdxComparator { 325 bool operator()(const std::vector<Value*> &LHS, 326 const std::vector<Value*> &RHS) const { 327 unsigned idx = 0; 328 for (; idx < LHS.size() && idx < RHS.size(); ++idx) { 329 if (LHS[idx] != RHS[idx]) { 330 return cast<ConstantInt>(LHS[idx])->getZExtValue() < 331 cast<ConstantInt>(RHS[idx])->getZExtValue(); 332 } 333 } 334 335 // Return less than if we ran out of stuff in LHS and we didn't run out of 336 // stuff in RHS. 337 return idx == LHS.size() && idx != RHS.size(); 338 } 339 }; 340} 341 342 343/// DoPromotion - This method actually performs the promotion of the specified 344/// arguments, and returns the new function. At this point, we know that it's 345/// safe to do so. 346Function *ArgPromotion::DoPromotion(Function *F, 347 SmallPtrSet<Argument*, 8> &ArgsToPromote) { 348 349 // Start by computing a new prototype for the function, which is the same as 350 // the old function, but has modified arguments. 351 const FunctionType *FTy = F->getFunctionType(); 352 std::vector<const Type*> Params; 353 354 typedef std::set<std::vector<Value*>, GEPIdxComparator> ScalarizeTable; 355 356 // ScalarizedElements - If we are promoting a pointer that has elements 357 // accessed out of it, keep track of which elements are accessed so that we 358 // can add one argument for each. 359 // 360 // Arguments that are directly loaded will have a zero element value here, to 361 // handle cases where there are both a direct load and GEP accesses. 362 // 363 std::map<Argument*, ScalarizeTable> ScalarizedElements; 364 365 // OriginalLoads - Keep track of a representative load instruction from the 366 // original function so that we can tell the alias analysis implementation 367 // what the new GEP/Load instructions we are inserting look like. 368 std::map<std::vector<Value*>, LoadInst*> OriginalLoads; 369 370 // ParamAttrs - Keep track of the parameter attributes for the arguments 371 // that we are *not* promoting. For the ones that we do promote, the parameter 372 // attributes are lost 373 ParamAttrsVector ParamAttrsVec; 374 const ParamAttrsList *PAL = F->getParamAttrs(); 375 376 unsigned index = 1; 377 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; 378 ++I, ++index) 379 if (!ArgsToPromote.count(I)) { 380 Params.push_back(I->getType()); 381 if (PAL) { 382 unsigned attrs = PAL->getParamAttrs(index); 383 if (attrs) 384 ParamAttrsVec.push_back(ParamAttrsWithIndex::get(Params.size(), 385 attrs)); 386 } 387 } else if (I->use_empty()) { 388 ++NumArgumentsDead; 389 } else { 390 // Okay, this is being promoted. Check to see if there are any GEP uses 391 // of the argument. 392 ScalarizeTable &ArgIndices = ScalarizedElements[I]; 393 for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E; 394 ++UI) { 395 Instruction *User = cast<Instruction>(*UI); 396 assert(isa<LoadInst>(User) || isa<GetElementPtrInst>(User)); 397 std::vector<Value*> Indices(User->op_begin()+1, User->op_end()); 398 ArgIndices.insert(Indices); 399 LoadInst *OrigLoad; 400 if (LoadInst *L = dyn_cast<LoadInst>(User)) 401 OrigLoad = L; 402 else 403 OrigLoad = cast<LoadInst>(User->use_back()); 404 OriginalLoads[Indices] = OrigLoad; 405 } 406 407 // Add a parameter to the function for each element passed in. 408 for (ScalarizeTable::iterator SI = ArgIndices.begin(), 409 E = ArgIndices.end(); SI != E; ++SI) 410 Params.push_back(GetElementPtrInst::getIndexedType(I->getType(), 411 SI->begin(), 412 SI->end())); 413 414 if (ArgIndices.size() == 1 && ArgIndices.begin()->empty()) 415 ++NumArgumentsPromoted; 416 else 417 ++NumAggregatesPromoted; 418 } 419 420 const Type *RetTy = FTy->getReturnType(); 421 422 // Recompute the parameter attributes list based on the new arguments for 423 // the function. 424 if (ParamAttrsVec.empty()) 425 PAL = 0; 426 else 427 PAL = ParamAttrsList::get(ParamAttrsVec); 428 429 // Work around LLVM bug PR56: the CWriter cannot emit varargs functions which 430 // have zero fixed arguments. 431 bool ExtraArgHack = false; 432 if (Params.empty() && FTy->isVarArg()) { 433 ExtraArgHack = true; 434 Params.push_back(Type::Int32Ty); 435 } 436 437 // Construct the new function type using the new arguments. 438 FunctionType *NFTy = FunctionType::get(RetTy, Params, FTy->isVarArg()); 439 440 // Create the new function body and insert it into the module... 441 Function *NF = new Function(NFTy, F->getLinkage(), F->getName()); 442 NF->setCallingConv(F->getCallingConv()); 443 NF->setParamAttrs(PAL); 444 if (F->hasCollector()) 445 NF->setCollector(F->getCollector()); 446 F->getParent()->getFunctionList().insert(F, NF); 447 448 // Get the alias analysis information that we need to update to reflect our 449 // changes. 450 AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 451 452 // Loop over all of the callers of the function, transforming the call sites 453 // to pass in the loaded pointers. 454 // 455 std::vector<Value*> Args; 456 while (!F->use_empty()) { 457 CallSite CS = CallSite::get(F->use_back()); 458 Instruction *Call = CS.getInstruction(); 459 460 // Loop over the operands, inserting GEP and loads in the caller as 461 // appropriate. 462 CallSite::arg_iterator AI = CS.arg_begin(); 463 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); 464 I != E; ++I, ++AI) 465 if (!ArgsToPromote.count(I)) 466 Args.push_back(*AI); // Unmodified argument 467 else if (!I->use_empty()) { 468 // Non-dead argument: insert GEPs and loads as appropriate. 469 ScalarizeTable &ArgIndices = ScalarizedElements[I]; 470 for (ScalarizeTable::iterator SI = ArgIndices.begin(), 471 E = ArgIndices.end(); SI != E; ++SI) { 472 Value *V = *AI; 473 LoadInst *OrigLoad = OriginalLoads[*SI]; 474 if (!SI->empty()) { 475 V = new GetElementPtrInst(V, SI->begin(), SI->end(), 476 V->getName()+".idx", Call); 477 AA.copyValue(OrigLoad->getOperand(0), V); 478 } 479 Args.push_back(new LoadInst(V, V->getName()+".val", Call)); 480 AA.copyValue(OrigLoad, Args.back()); 481 } 482 } 483 484 if (ExtraArgHack) 485 Args.push_back(Constant::getNullValue(Type::Int32Ty)); 486 487 // Push any varargs arguments on the list 488 for (; AI != CS.arg_end(); ++AI) 489 Args.push_back(*AI); 490 491 Instruction *New; 492 if (InvokeInst *II = dyn_cast<InvokeInst>(Call)) { 493 New = new InvokeInst(NF, II->getNormalDest(), II->getUnwindDest(), 494 Args.begin(), Args.end(), "", Call); 495 cast<InvokeInst>(New)->setCallingConv(CS.getCallingConv()); 496 cast<InvokeInst>(New)->setParamAttrs(PAL); 497 } else { 498 New = new CallInst(NF, Args.begin(), Args.end(), "", Call); 499 cast<CallInst>(New)->setCallingConv(CS.getCallingConv()); 500 cast<CallInst>(New)->setParamAttrs(PAL); 501 if (cast<CallInst>(Call)->isTailCall()) 502 cast<CallInst>(New)->setTailCall(); 503 } 504 Args.clear(); 505 506 // Update the alias analysis implementation to know that we are replacing 507 // the old call with a new one. 508 AA.replaceWithNewValue(Call, New); 509 510 if (!Call->use_empty()) { 511 Call->replaceAllUsesWith(New); 512 New->takeName(Call); 513 } 514 515 // Finally, remove the old call from the program, reducing the use-count of 516 // F. 517 Call->eraseFromParent(); 518 } 519 520 // Since we have now created the new function, splice the body of the old 521 // function right into the new function, leaving the old rotting hulk of the 522 // function empty. 523 NF->getBasicBlockList().splice(NF->begin(), F->getBasicBlockList()); 524 525 // Loop over the argument list, transfering uses of the old arguments over to 526 // the new arguments, also transfering over the names as well. 527 // 528 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(), 529 I2 = NF->arg_begin(); I != E; ++I) 530 if (!ArgsToPromote.count(I)) { 531 // If this is an unmodified argument, move the name and users over to the 532 // new version. 533 I->replaceAllUsesWith(I2); 534 I2->takeName(I); 535 AA.replaceWithNewValue(I, I2); 536 ++I2; 537 } else if (I->use_empty()) { 538 AA.deleteValue(I); 539 } else { 540 // Otherwise, if we promoted this argument, then all users are load 541 // instructions, and all loads should be using the new argument that we 542 // added. 543 ScalarizeTable &ArgIndices = ScalarizedElements[I]; 544 545 while (!I->use_empty()) { 546 if (LoadInst *LI = dyn_cast<LoadInst>(I->use_back())) { 547 assert(ArgIndices.begin()->empty() && 548 "Load element should sort to front!"); 549 I2->setName(I->getName()+".val"); 550 LI->replaceAllUsesWith(I2); 551 AA.replaceWithNewValue(LI, I2); 552 LI->eraseFromParent(); 553 DOUT << "*** Promoted load of argument '" << I->getName() 554 << "' in function '" << F->getName() << "'\n"; 555 } else { 556 GetElementPtrInst *GEP = cast<GetElementPtrInst>(I->use_back()); 557 std::vector<Value*> Operands(GEP->op_begin()+1, GEP->op_end()); 558 559 Function::arg_iterator TheArg = I2; 560 for (ScalarizeTable::iterator It = ArgIndices.begin(); 561 *It != Operands; ++It, ++TheArg) { 562 assert(It != ArgIndices.end() && "GEP not handled??"); 563 } 564 565 std::string NewName = I->getName(); 566 for (unsigned i = 0, e = Operands.size(); i != e; ++i) 567 if (ConstantInt *CI = dyn_cast<ConstantInt>(Operands[i])) 568 NewName += "." + CI->getValue().toStringUnsigned(10); 569 else 570 NewName += ".x"; 571 TheArg->setName(NewName+".val"); 572 573 DOUT << "*** Promoted agg argument '" << TheArg->getName() 574 << "' of function '" << F->getName() << "'\n"; 575 576 // All of the uses must be load instructions. Replace them all with 577 // the argument specified by ArgNo. 578 while (!GEP->use_empty()) { 579 LoadInst *L = cast<LoadInst>(GEP->use_back()); 580 L->replaceAllUsesWith(TheArg); 581 AA.replaceWithNewValue(L, TheArg); 582 L->eraseFromParent(); 583 } 584 AA.deleteValue(GEP); 585 GEP->eraseFromParent(); 586 } 587 } 588 589 // Increment I2 past all of the arguments added for this promoted pointer. 590 for (unsigned i = 0, e = ArgIndices.size(); i != e; ++i) 591 ++I2; 592 } 593 594 // Notify the alias analysis implementation that we inserted a new argument. 595 if (ExtraArgHack) 596 AA.copyValue(Constant::getNullValue(Type::Int32Ty), NF->arg_begin()); 597 598 599 // Tell the alias analysis that the old function is about to disappear. 600 AA.replaceWithNewValue(F, NF); 601 602 // Now that the old function is dead, delete it. 603 F->eraseFromParent(); 604 return NF; 605} 606