LLVM API Documentation
00001 //===-- ArgumentPromotion.cpp - Promote by-reference arguments ------------===// 00002 // 00003 // The LLVM Compiler Infrastructure 00004 // 00005 // This file was developed by the LLVM research group and is distributed under 00006 // the University of Illinois Open Source License. See LICENSE.TXT for details. 00007 // 00008 //===----------------------------------------------------------------------===// 00009 // 00010 // This pass promotes "by reference" arguments to be "by value" arguments. In 00011 // practice, this means looking for internal functions that have pointer 00012 // arguments. If we can prove, through the use of alias analysis, that an 00013 // argument is *only* loaded, then we can pass the value into the function 00014 // instead of the address of the value. This can cause recursive simplification 00015 // of code and lead to the elimination of allocas (especially in C++ template 00016 // code like the STL). 00017 // 00018 // This pass also handles aggregate arguments that are passed into a function, 00019 // scalarizing them if the elements of the aggregate are only loaded. Note that 00020 // we refuse to scalarize aggregates which would require passing in more than 00021 // three operands to the function, because we don't want to pass thousands of 00022 // operands for a large array or structure! 00023 // 00024 // Note that this transformation could also be done for arguments that are only 00025 // stored to (returning the value instead), but we do not currently handle that 00026 // case. This case would be best handled when and if we start supporting 00027 // multiple return values from functions. 00028 // 00029 //===----------------------------------------------------------------------===// 00030 00031 #define DEBUG_TYPE "argpromotion" 00032 #include "llvm/Transforms/IPO.h" 00033 #include "llvm/Constants.h" 00034 #include "llvm/DerivedTypes.h" 00035 #include "llvm/Module.h" 00036 #include "llvm/CallGraphSCCPass.h" 00037 #include "llvm/Instructions.h" 00038 #include "llvm/Analysis/AliasAnalysis.h" 00039 #include "llvm/Analysis/CallGraph.h" 00040 #include "llvm/Target/TargetData.h" 00041 #include "llvm/Support/CallSite.h" 00042 #include "llvm/Support/CFG.h" 00043 #include "llvm/Support/Debug.h" 00044 #include "llvm/ADT/DepthFirstIterator.h" 00045 #include "llvm/ADT/Statistic.h" 00046 #include "llvm/ADT/StringExtras.h" 00047 #include <iostream> 00048 #include <set> 00049 using namespace llvm; 00050 00051 namespace { 00052 Statistic<> NumArgumentsPromoted("argpromotion", 00053 "Number of pointer arguments promoted"); 00054 Statistic<> NumAggregatesPromoted("argpromotion", 00055 "Number of aggregate arguments promoted"); 00056 Statistic<> NumArgumentsDead("argpromotion", 00057 "Number of dead pointer args eliminated"); 00058 00059 /// ArgPromotion - The 'by reference' to 'by value' argument promotion pass. 00060 /// 00061 struct ArgPromotion : public CallGraphSCCPass { 00062 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 00063 AU.addRequired<AliasAnalysis>(); 00064 AU.addRequired<TargetData>(); 00065 CallGraphSCCPass::getAnalysisUsage(AU); 00066 } 00067 00068 virtual bool runOnSCC(const std::vector<CallGraphNode *> &SCC); 00069 private: 00070 bool PromoteArguments(CallGraphNode *CGN); 00071 bool isSafeToPromoteArgument(Argument *Arg) const; 00072 Function *DoPromotion(Function *F, std::vector<Argument*> &ArgsToPromote); 00073 }; 00074 00075 RegisterOpt<ArgPromotion> X("argpromotion", 00076 "Promote 'by reference' arguments to scalars"); 00077 } 00078 00079 ModulePass *llvm::createArgumentPromotionPass() { 00080 return new ArgPromotion(); 00081 } 00082 00083 bool ArgPromotion::runOnSCC(const std::vector<CallGraphNode *> &SCC) { 00084 bool Changed = false, LocalChange; 00085 00086 do { // Iterate until we stop promoting from this SCC. 00087 LocalChange = false; 00088 // Attempt to promote arguments from all functions in this SCC. 00089 for (unsigned i = 0, e = SCC.size(); i != e; ++i) 00090 LocalChange |= PromoteArguments(SCC[i]); 00091 Changed |= LocalChange; // Remember that we changed something. 00092 } while (LocalChange); 00093 00094 return Changed; 00095 } 00096 00097 /// PromoteArguments - This method checks the specified function to see if there 00098 /// are any promotable arguments and if it is safe to promote the function (for 00099 /// example, all callers are direct). If safe to promote some arguments, it 00100 /// calls the DoPromotion method. 00101 /// 00102 bool ArgPromotion::PromoteArguments(CallGraphNode *CGN) { 00103 Function *F = CGN->getFunction(); 00104 00105 // Make sure that it is local to this module. 00106 if (!F || !F->hasInternalLinkage()) return false; 00107 00108 // First check: see if there are any pointer arguments! If not, quick exit. 00109 std::vector<Argument*> PointerArgs; 00110 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; ++I) 00111 if (isa<PointerType>(I->getType())) 00112 PointerArgs.push_back(I); 00113 if (PointerArgs.empty()) return false; 00114 00115 // Second check: make sure that all callers are direct callers. We can't 00116 // transform functions that have indirect callers. 00117 for (Value::use_iterator UI = F->use_begin(), E = F->use_end(); 00118 UI != E; ++UI) { 00119 CallSite CS = CallSite::get(*UI); 00120 if (!CS.getInstruction()) // "Taking the address" of the function 00121 return false; 00122 00123 // Ensure that this call site is CALLING the function, not passing it as 00124 // an argument. 00125 for (CallSite::arg_iterator AI = CS.arg_begin(), E = CS.arg_end(); 00126 AI != E; ++AI) 00127 if (*AI == F) return false; // Passing the function address in! 00128 } 00129 00130 // Check to see which arguments are promotable. If an argument is not 00131 // promotable, remove it from the PointerArgs vector. 00132 for (unsigned i = 0; i != PointerArgs.size(); ++i) 00133 if (!isSafeToPromoteArgument(PointerArgs[i])) { 00134 std::swap(PointerArgs[i--], PointerArgs.back()); 00135 PointerArgs.pop_back(); 00136 } 00137 00138 // No promotable pointer arguments. 00139 if (PointerArgs.empty()) return false; 00140 00141 // Okay, promote all of the arguments are rewrite the callees! 00142 Function *NewF = DoPromotion(F, PointerArgs); 00143 00144 // Update the call graph to know that the old function is gone. 00145 getAnalysis<CallGraph>().changeFunction(F, NewF); 00146 return true; 00147 } 00148 00149 /// IsAlwaysValidPointer - Return true if the specified pointer is always legal 00150 /// to load. 00151 static bool IsAlwaysValidPointer(Value *V) { 00152 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true; 00153 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) 00154 return IsAlwaysValidPointer(GEP->getOperand(0)); 00155 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) 00156 if (CE->getOpcode() == Instruction::GetElementPtr) 00157 return IsAlwaysValidPointer(CE->getOperand(0)); 00158 00159 return false; 00160 } 00161 00162 /// AllCalleesPassInValidPointerForArgument - Return true if we can prove that 00163 /// all callees pass in a valid pointer for the specified function argument. 00164 static bool AllCalleesPassInValidPointerForArgument(Argument *Arg) { 00165 Function *Callee = Arg->getParent(); 00166 00167 unsigned ArgNo = std::distance(Callee->arg_begin(), Function::arg_iterator(Arg)); 00168 00169 // Look at all call sites of the function. At this pointer we know we only 00170 // have direct callees. 00171 for (Value::use_iterator UI = Callee->use_begin(), E = Callee->use_end(); 00172 UI != E; ++UI) { 00173 CallSite CS = CallSite::get(*UI); 00174 assert(CS.getInstruction() && "Should only have direct calls!"); 00175 00176 if (!IsAlwaysValidPointer(CS.getArgument(ArgNo))) 00177 return false; 00178 } 00179 return true; 00180 } 00181 00182 00183 /// isSafeToPromoteArgument - As you might guess from the name of this method, 00184 /// it checks to see if it is both safe and useful to promote the argument. 00185 /// This method limits promotion of aggregates to only promote up to three 00186 /// elements of the aggregate in order to avoid exploding the number of 00187 /// arguments passed in. 00188 bool ArgPromotion::isSafeToPromoteArgument(Argument *Arg) const { 00189 // We can only promote this argument if all of the uses are loads, or are GEP 00190 // instructions (with constant indices) that are subsequently loaded. 00191 bool HasLoadInEntryBlock = false; 00192 BasicBlock *EntryBlock = Arg->getParent()->begin(); 00193 std::vector<LoadInst*> Loads; 00194 std::vector<std::vector<ConstantInt*> > GEPIndices; 00195 for (Value::use_iterator UI = Arg->use_begin(), E = Arg->use_end(); 00196 UI != E; ++UI) 00197 if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) { 00198 if (LI->isVolatile()) return false; // Don't hack volatile loads 00199 Loads.push_back(LI); 00200 HasLoadInEntryBlock |= LI->getParent() == EntryBlock; 00201 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(*UI)) { 00202 if (GEP->use_empty()) { 00203 // Dead GEP's cause trouble later. Just remove them if we run into 00204 // them. 00205 getAnalysis<AliasAnalysis>().deleteValue(GEP); 00206 GEP->getParent()->getInstList().erase(GEP); 00207 return isSafeToPromoteArgument(Arg); 00208 } 00209 // Ensure that all of the indices are constants. 00210 std::vector<ConstantInt*> Operands; 00211 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i) 00212 if (ConstantInt *C = dyn_cast<ConstantInt>(GEP->getOperand(i))) 00213 Operands.push_back(C); 00214 else 00215 return false; // Not a constant operand GEP! 00216 00217 // Ensure that the only users of the GEP are load instructions. 00218 for (Value::use_iterator UI = GEP->use_begin(), E = GEP->use_end(); 00219 UI != E; ++UI) 00220 if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) { 00221 if (LI->isVolatile()) return false; // Don't hack volatile loads 00222 Loads.push_back(LI); 00223 HasLoadInEntryBlock |= LI->getParent() == EntryBlock; 00224 } else { 00225 return false; 00226 } 00227 00228 // See if there is already a GEP with these indices. If not, check to 00229 // make sure that we aren't promoting too many elements. If so, nothing 00230 // to do. 00231 if (std::find(GEPIndices.begin(), GEPIndices.end(), Operands) == 00232 GEPIndices.end()) { 00233 if (GEPIndices.size() == 3) { 00234 DEBUG(std::cerr << "argpromotion disable promoting argument '" 00235 << Arg->getName() << "' because it would require adding more " 00236 << "than 3 arguments to the function.\n"); 00237 // We limit aggregate promotion to only promoting up to three elements 00238 // of the aggregate. 00239 return false; 00240 } 00241 GEPIndices.push_back(Operands); 00242 } 00243 } else { 00244 return false; // Not a load or a GEP. 00245 } 00246 00247 if (Loads.empty()) return true; // No users, this is a dead argument. 00248 00249 // If we decide that we want to promote this argument, the value is going to 00250 // be unconditionally loaded in all callees. This is only safe to do if the 00251 // pointer was going to be unconditionally loaded anyway (i.e. there is a load 00252 // of the pointer in the entry block of the function) or if we can prove that 00253 // all pointers passed in are always to legal locations (for example, no null 00254 // pointers are passed in, no pointers to free'd memory, etc). 00255 if (!HasLoadInEntryBlock && !AllCalleesPassInValidPointerForArgument(Arg)) 00256 return false; // Cannot prove that this is safe!! 00257 00258 // Okay, now we know that the argument is only used by load instructions and 00259 // it is safe to unconditionally load the pointer. Use alias analysis to 00260 // check to see if the pointer is guaranteed to not be modified from entry of 00261 // the function to each of the load instructions. 00262 Function &F = *Arg->getParent(); 00263 00264 // Because there could be several/many load instructions, remember which 00265 // blocks we know to be transparent to the load. 00266 std::set<BasicBlock*> TranspBlocks; 00267 00268 AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 00269 TargetData &TD = getAnalysis<TargetData>(); 00270 00271 for (unsigned i = 0, e = Loads.size(); i != e; ++i) { 00272 // Check to see if the load is invalidated from the start of the block to 00273 // the load itself. 00274 LoadInst *Load = Loads[i]; 00275 BasicBlock *BB = Load->getParent(); 00276 00277 const PointerType *LoadTy = 00278 cast<PointerType>(Load->getOperand(0)->getType()); 00279 unsigned LoadSize = (unsigned)TD.getTypeSize(LoadTy->getElementType()); 00280 00281 if (AA.canInstructionRangeModify(BB->front(), *Load, Arg, LoadSize)) 00282 return false; // Pointer is invalidated! 00283 00284 // Now check every path from the entry block to the load for transparency. 00285 // To do this, we perform a depth first search on the inverse CFG from the 00286 // loading block. 00287 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 00288 for (idf_ext_iterator<BasicBlock*> I = idf_ext_begin(*PI, TranspBlocks), 00289 E = idf_ext_end(*PI, TranspBlocks); I != E; ++I) 00290 if (AA.canBasicBlockModify(**I, Arg, LoadSize)) 00291 return false; 00292 } 00293 00294 // If the path from the entry of the function to each load is free of 00295 // instructions that potentially invalidate the load, we can make the 00296 // transformation! 00297 return true; 00298 } 00299 00300 namespace { 00301 /// GEPIdxComparator - Provide a strong ordering for GEP indices. All Value* 00302 /// elements are instances of ConstantInt. 00303 /// 00304 struct GEPIdxComparator { 00305 bool operator()(const std::vector<Value*> &LHS, 00306 const std::vector<Value*> &RHS) const { 00307 unsigned idx = 0; 00308 for (; idx < LHS.size() && idx < RHS.size(); ++idx) { 00309 if (LHS[idx] != RHS[idx]) { 00310 return cast<ConstantInt>(LHS[idx])->getRawValue() < 00311 cast<ConstantInt>(RHS[idx])->getRawValue(); 00312 } 00313 } 00314 00315 // Return less than if we ran out of stuff in LHS and we didn't run out of 00316 // stuff in RHS. 00317 return idx == LHS.size() && idx != RHS.size(); 00318 } 00319 }; 00320 } 00321 00322 00323 /// DoPromotion - This method actually performs the promotion of the specified 00324 /// arguments, and returns the new function. At this point, we know that it's 00325 /// safe to do so. 00326 Function *ArgPromotion::DoPromotion(Function *F, 00327 std::vector<Argument*> &Args2Prom) { 00328 std::set<Argument*> ArgsToPromote(Args2Prom.begin(), Args2Prom.end()); 00329 00330 // Start by computing a new prototype for the function, which is the same as 00331 // the old function, but has modified arguments. 00332 const FunctionType *FTy = F->getFunctionType(); 00333 std::vector<const Type*> Params; 00334 00335 typedef std::set<std::vector<Value*>, GEPIdxComparator> ScalarizeTable; 00336 00337 // ScalarizedElements - If we are promoting a pointer that has elements 00338 // accessed out of it, keep track of which elements are accessed so that we 00339 // can add one argument for each. 00340 // 00341 // Arguments that are directly loaded will have a zero element value here, to 00342 // handle cases where there are both a direct load and GEP accesses. 00343 // 00344 std::map<Argument*, ScalarizeTable> ScalarizedElements; 00345 00346 // OriginalLoads - Keep track of a representative load instruction from the 00347 // original function so that we can tell the alias analysis implementation 00348 // what the new GEP/Load instructions we are inserting look like. 00349 std::map<std::vector<Value*>, LoadInst*> OriginalLoads; 00350 00351 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; ++I) 00352 if (!ArgsToPromote.count(I)) { 00353 Params.push_back(I->getType()); 00354 } else if (I->use_empty()) { 00355 ++NumArgumentsDead; 00356 } else { 00357 // Okay, this is being promoted. Check to see if there are any GEP uses 00358 // of the argument. 00359 ScalarizeTable &ArgIndices = ScalarizedElements[I]; 00360 for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E; 00361 ++UI) { 00362 Instruction *User = cast<Instruction>(*UI); 00363 assert(isa<LoadInst>(User) || isa<GetElementPtrInst>(User)); 00364 std::vector<Value*> Indices(User->op_begin()+1, User->op_end()); 00365 ArgIndices.insert(Indices); 00366 LoadInst *OrigLoad; 00367 if (LoadInst *L = dyn_cast<LoadInst>(User)) 00368 OrigLoad = L; 00369 else 00370 OrigLoad = cast<LoadInst>(User->use_back()); 00371 OriginalLoads[Indices] = OrigLoad; 00372 } 00373 00374 // Add a parameter to the function for each element passed in. 00375 for (ScalarizeTable::iterator SI = ArgIndices.begin(), 00376 E = ArgIndices.end(); SI != E; ++SI) 00377 Params.push_back(GetElementPtrInst::getIndexedType(I->getType(), *SI)); 00378 00379 if (ArgIndices.size() == 1 && ArgIndices.begin()->empty()) 00380 ++NumArgumentsPromoted; 00381 else 00382 ++NumAggregatesPromoted; 00383 } 00384 00385 const Type *RetTy = FTy->getReturnType(); 00386 00387 // Work around LLVM bug PR56: the CWriter cannot emit varargs functions which 00388 // have zero fixed arguments. 00389 bool ExtraArgHack = false; 00390 if (Params.empty() && FTy->isVarArg()) { 00391 ExtraArgHack = true; 00392 Params.push_back(Type::IntTy); 00393 } 00394 FunctionType *NFTy = FunctionType::get(RetTy, Params, FTy->isVarArg()); 00395 00396 // Create the new function body and insert it into the module... 00397 Function *NF = new Function(NFTy, F->getLinkage(), F->getName()); 00398 NF->setCallingConv(F->getCallingConv()); 00399 F->getParent()->getFunctionList().insert(F, NF); 00400 00401 // Get the alias analysis information that we need to update to reflect our 00402 // changes. 00403 AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 00404 00405 // Loop over all of the callers of the function, transforming the call sites 00406 // to pass in the loaded pointers. 00407 // 00408 std::vector<Value*> Args; 00409 while (!F->use_empty()) { 00410 CallSite CS = CallSite::get(F->use_back()); 00411 Instruction *Call = CS.getInstruction(); 00412 00413 // Loop over the operands, inserting GEP and loads in the caller as 00414 // appropriate. 00415 CallSite::arg_iterator AI = CS.arg_begin(); 00416 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); 00417 I != E; ++I, ++AI) 00418 if (!ArgsToPromote.count(I)) 00419 Args.push_back(*AI); // Unmodified argument 00420 else if (!I->use_empty()) { 00421 // Non-dead argument: insert GEPs and loads as appropriate. 00422 ScalarizeTable &ArgIndices = ScalarizedElements[I]; 00423 for (ScalarizeTable::iterator SI = ArgIndices.begin(), 00424 E = ArgIndices.end(); SI != E; ++SI) { 00425 Value *V = *AI; 00426 LoadInst *OrigLoad = OriginalLoads[*SI]; 00427 if (!SI->empty()) { 00428 V = new GetElementPtrInst(V, *SI, V->getName()+".idx", Call); 00429 AA.copyValue(OrigLoad->getOperand(0), V); 00430 } 00431 Args.push_back(new LoadInst(V, V->getName()+".val", Call)); 00432 AA.copyValue(OrigLoad, Args.back()); 00433 } 00434 } 00435 00436 if (ExtraArgHack) 00437 Args.push_back(Constant::getNullValue(Type::IntTy)); 00438 00439 // Push any varargs arguments on the list 00440 for (; AI != CS.arg_end(); ++AI) 00441 Args.push_back(*AI); 00442 00443 Instruction *New; 00444 if (InvokeInst *II = dyn_cast<InvokeInst>(Call)) { 00445 New = new InvokeInst(NF, II->getNormalDest(), II->getUnwindDest(), 00446 Args, "", Call); 00447 cast<InvokeInst>(New)->setCallingConv(CS.getCallingConv()); 00448 } else { 00449 New = new CallInst(NF, Args, "", Call); 00450 cast<CallInst>(New)->setCallingConv(CS.getCallingConv()); 00451 if (cast<CallInst>(Call)->isTailCall()) 00452 cast<CallInst>(New)->setTailCall(); 00453 } 00454 Args.clear(); 00455 00456 // Update the alias analysis implementation to know that we are replacing 00457 // the old call with a new one. 00458 AA.replaceWithNewValue(Call, New); 00459 00460 if (!Call->use_empty()) { 00461 Call->replaceAllUsesWith(New); 00462 std::string Name = Call->getName(); 00463 Call->setName(""); 00464 New->setName(Name); 00465 } 00466 00467 // Finally, remove the old call from the program, reducing the use-count of 00468 // F. 00469 Call->getParent()->getInstList().erase(Call); 00470 } 00471 00472 // Since we have now created the new function, splice the body of the old 00473 // function right into the new function, leaving the old rotting hulk of the 00474 // function empty. 00475 NF->getBasicBlockList().splice(NF->begin(), F->getBasicBlockList()); 00476 00477 // Loop over the argument list, transfering uses of the old arguments over to 00478 // the new arguments, also transfering over the names as well. 00479 // 00480 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(), I2 = NF->arg_begin(); 00481 I != E; ++I) 00482 if (!ArgsToPromote.count(I)) { 00483 // If this is an unmodified argument, move the name and users over to the 00484 // new version. 00485 I->replaceAllUsesWith(I2); 00486 I2->setName(I->getName()); 00487 AA.replaceWithNewValue(I, I2); 00488 ++I2; 00489 } else if (I->use_empty()) { 00490 AA.deleteValue(I); 00491 } else { 00492 // Otherwise, if we promoted this argument, then all users are load 00493 // instructions, and all loads should be using the new argument that we 00494 // added. 00495 ScalarizeTable &ArgIndices = ScalarizedElements[I]; 00496 00497 while (!I->use_empty()) { 00498 if (LoadInst *LI = dyn_cast<LoadInst>(I->use_back())) { 00499 assert(ArgIndices.begin()->empty() && 00500 "Load element should sort to front!"); 00501 I2->setName(I->getName()+".val"); 00502 LI->replaceAllUsesWith(I2); 00503 AA.replaceWithNewValue(LI, I2); 00504 LI->getParent()->getInstList().erase(LI); 00505 DEBUG(std::cerr << "*** Promoted load of argument '" << I->getName() 00506 << "' in function '" << F->getName() << "'\n"); 00507 } else { 00508 GetElementPtrInst *GEP = cast<GetElementPtrInst>(I->use_back()); 00509 std::vector<Value*> Operands(GEP->op_begin()+1, GEP->op_end()); 00510 00511 unsigned ArgNo = 0; 00512 Function::arg_iterator TheArg = I2; 00513 for (ScalarizeTable::iterator It = ArgIndices.begin(); 00514 *It != Operands; ++It, ++TheArg) { 00515 assert(It != ArgIndices.end() && "GEP not handled??"); 00516 } 00517 00518 std::string NewName = I->getName(); 00519 for (unsigned i = 0, e = Operands.size(); i != e; ++i) 00520 if (ConstantInt *CI = dyn_cast<ConstantInt>(Operands[i])) 00521 NewName += "."+itostr((int64_t)CI->getRawValue()); 00522 else 00523 NewName += ".x"; 00524 TheArg->setName(NewName+".val"); 00525 00526 DEBUG(std::cerr << "*** Promoted agg argument '" << TheArg->getName() 00527 << "' of function '" << F->getName() << "'\n"); 00528 00529 // All of the uses must be load instructions. Replace them all with 00530 // the argument specified by ArgNo. 00531 while (!GEP->use_empty()) { 00532 LoadInst *L = cast<LoadInst>(GEP->use_back()); 00533 L->replaceAllUsesWith(TheArg); 00534 AA.replaceWithNewValue(L, TheArg); 00535 L->getParent()->getInstList().erase(L); 00536 } 00537 AA.deleteValue(GEP); 00538 GEP->getParent()->getInstList().erase(GEP); 00539 } 00540 } 00541 00542 // Increment I2 past all of the arguments added for this promoted pointer. 00543 for (unsigned i = 0, e = ArgIndices.size(); i != e; ++i) 00544 ++I2; 00545 } 00546 00547 // Notify the alias analysis implementation that we inserted a new argument. 00548 if (ExtraArgHack) 00549 AA.copyValue(Constant::getNullValue(Type::IntTy), NF->arg_begin()); 00550 00551 00552 // Tell the alias analysis that the old function is about to disappear. 00553 AA.replaceWithNewValue(F, NF); 00554 00555 // Now that the old function is dead, delete it. 00556 F->getParent()->getFunctionList().erase(F); 00557 return NF; 00558 }