DwarfEHPrepare.cpp revision 19b59f45bddaaabef125d3deec372552a8f0df39
1//===-- DwarfEHPrepare - Prepare exception handling for code generation ---===// 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 mulches exception handling code into a form adapted to code 11// generation. Required if using dwarf exception handling. 12// 13//===----------------------------------------------------------------------===// 14 15#define DEBUG_TYPE "dwarfehprepare" 16#include "llvm/Function.h" 17#include "llvm/Instructions.h" 18#include "llvm/IntrinsicInst.h" 19#include "llvm/Module.h" 20#include "llvm/Pass.h" 21#include "llvm/ADT/Statistic.h" 22#include "llvm/Analysis/Dominators.h" 23#include "llvm/CodeGen/Passes.h" 24#include "llvm/MC/MCAsmInfo.h" 25#include "llvm/Target/TargetLowering.h" 26#include "llvm/Transforms/Utils/BasicBlockUtils.h" 27#include "llvm/Transforms/Utils/PromoteMemToReg.h" 28using namespace llvm; 29 30STATISTIC(NumLandingPadsSplit, "Number of landing pads split"); 31STATISTIC(NumUnwindsLowered, "Number of unwind instructions lowered"); 32STATISTIC(NumExceptionValuesMoved, "Number of eh.exception calls moved"); 33STATISTIC(NumStackTempsIntroduced, "Number of stack temporaries introduced"); 34 35namespace { 36 class DwarfEHPrepare : public FunctionPass { 37 const TargetLowering *TLI; 38 bool CompileFast; 39 40 // The eh.exception intrinsic. 41 Function *ExceptionValueIntrinsic; 42 43 // The eh.selector intrinsic. 44 Function *SelectorIntrinsic; 45 46 // _Unwind_Resume_or_Rethrow call. 47 Constant *URoR; 48 49 // The EH language-specific catch-all type. 50 GlobalVariable *EHCatchAllValue; 51 52 // _Unwind_Resume or the target equivalent. 53 Constant *RewindFunction; 54 55 // Dominator info is used when turning stack temporaries into registers. 56 DominatorTree *DT; 57 DominanceFrontier *DF; 58 59 // The function we are running on. 60 Function *F; 61 62 // The landing pads for this function. 63 typedef SmallPtrSet<BasicBlock*, 8> BBSet; 64 BBSet LandingPads; 65 66 // Stack temporary used to hold eh.exception values. 67 AllocaInst *ExceptionValueVar; 68 69 bool NormalizeLandingPads(); 70 bool LowerUnwinds(); 71 bool MoveExceptionValueCalls(); 72 bool FinishStackTemporaries(); 73 bool PromoteStackTemporaries(); 74 75 Instruction *CreateExceptionValueCall(BasicBlock *BB); 76 Instruction *CreateValueLoad(BasicBlock *BB); 77 78 /// CreateReadOfExceptionValue - Return the result of the eh.exception 79 /// intrinsic by calling the intrinsic if in a landing pad, or loading it 80 /// from the exception value variable otherwise. 81 Instruction *CreateReadOfExceptionValue(BasicBlock *BB) { 82 return LandingPads.count(BB) ? 83 CreateExceptionValueCall(BB) : CreateValueLoad(BB); 84 } 85 86 /// CleanupSelectors - Any remaining eh.selector intrinsic calls which still 87 /// use the ".llvm.eh.catch.all.value" call need to convert to using it's 88 /// initializer instead. 89 bool CleanupSelectors(); 90 91 /// FindAllCleanupSelectors - Find all eh.selector calls that are clean-ups. 92 void FindAllCleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels); 93 94 /// FindAllURoRInvokes - Find all URoR invokes in the function. 95 void FindAllURoRInvokes(SmallPtrSet<InvokeInst*, 32> &URoRInvokes); 96 97 /// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow" 98 /// calls. The "unwind" part of these invokes jump to a landing pad within 99 /// the current function. This is a candidate to merge the selector 100 /// associated with the URoR invoke with the one from the URoR's landing 101 /// pad. 102 bool HandleURoRInvokes(); 103 104 public: 105 static char ID; // Pass identification, replacement for typeid. 106 DwarfEHPrepare(const TargetLowering *tli, bool fast) : 107 FunctionPass(&ID), TLI(tli), CompileFast(fast), 108 ExceptionValueIntrinsic(0), SelectorIntrinsic(0), 109 URoR(0), EHCatchAllValue(0), RewindFunction(0) {} 110 111 virtual bool runOnFunction(Function &Fn); 112 113 // getAnalysisUsage - We need dominance frontiers for memory promotion. 114 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 115 if (!CompileFast) 116 AU.addRequired<DominatorTree>(); 117 AU.addPreserved<DominatorTree>(); 118 if (!CompileFast) 119 AU.addRequired<DominanceFrontier>(); 120 AU.addPreserved<DominanceFrontier>(); 121 } 122 123 const char *getPassName() const { 124 return "Exception handling preparation"; 125 } 126 127 }; 128} // end anonymous namespace 129 130char DwarfEHPrepare::ID = 0; 131 132FunctionPass *llvm::createDwarfEHPass(const TargetLowering *tli, bool fast) { 133 return new DwarfEHPrepare(tli, fast); 134} 135 136/// FindAllCleanupSelectors - Find all eh.selector calls that are clean-ups. 137void DwarfEHPrepare:: 138FindAllCleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels) { 139 for (Value::use_iterator 140 I = SelectorIntrinsic->use_begin(), 141 E = SelectorIntrinsic->use_end(); I != E; ++I) { 142 IntrinsicInst *SI = cast<IntrinsicInst>(I); 143 if (!SI || SI->getParent()->getParent() != F) continue; 144 145 unsigned NumOps = SI->getNumOperands(); 146 if (NumOps > 4) continue; 147 bool IsCleanUp = (NumOps == 3); 148 149 if (!IsCleanUp) 150 if (ConstantInt *CI = dyn_cast<ConstantInt>(SI->getOperand(3))) 151 IsCleanUp = (CI->getZExtValue() == 0); 152 153 if (IsCleanUp) 154 Sels.insert(SI); 155 } 156} 157 158/// FindAllURoRInvokes - Find all URoR invokes in the function. 159void DwarfEHPrepare:: 160FindAllURoRInvokes(SmallPtrSet<InvokeInst*, 32> &URoRInvokes) { 161 for (Value::use_iterator 162 I = URoR->use_begin(), 163 E = URoR->use_end(); I != E; ++I) { 164 if (InvokeInst *II = dyn_cast<InvokeInst>(I)) 165 URoRInvokes.insert(II); 166 } 167} 168 169/// CleanupSelectors - Any remaining eh.selector intrinsic calls which still use 170/// the ".llvm.eh.catch.all.value" call need to convert to using it's 171/// initializer instead. 172bool DwarfEHPrepare::CleanupSelectors() { 173 if (!EHCatchAllValue) return false; 174 175 if (!SelectorIntrinsic) { 176 SelectorIntrinsic = 177 Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_selector); 178 if (!SelectorIntrinsic) return false; 179 } 180 181 bool Changed = false; 182 for (Value::use_iterator 183 I = SelectorIntrinsic->use_begin(), 184 E = SelectorIntrinsic->use_end(); I != E; ++I) { 185 IntrinsicInst *Sel = dyn_cast<IntrinsicInst>(I); 186 if (!Sel || Sel->getParent()->getParent() != F) continue; 187 188 // Index of the ".llvm.eh.catch.all.value" variable. 189 unsigned OpIdx = Sel->getNumOperands() - 1; 190 GlobalVariable *GV = dyn_cast<GlobalVariable>(Sel->getOperand(OpIdx)); 191 if (GV != EHCatchAllValue) continue; 192 Sel->setOperand(OpIdx, EHCatchAllValue->getInitializer()); 193 Changed = true; 194 } 195 196 return Changed; 197} 198 199/// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow" calls. The 200/// "unwind" part of these invokes jump to a landing pad within the current 201/// function. This is a candidate to merge the selector associated with the URoR 202/// invoke with the one from the URoR's landing pad. 203bool DwarfEHPrepare::HandleURoRInvokes() { 204 if (!DT) return CleanupSelectors(); // We require DominatorTree information. 205 206 if (!EHCatchAllValue) { 207 EHCatchAllValue = 208 F->getParent()->getNamedGlobal(".llvm.eh.catch.all.value"); 209 if (!EHCatchAllValue) return false; 210 } 211 212 if (!SelectorIntrinsic) { 213 SelectorIntrinsic = 214 Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_selector); 215 if (!SelectorIntrinsic) return false; 216 } 217 218 if (!URoR) { 219 URoR = F->getParent()->getFunction("_Unwind_Resume_or_Rethrow"); 220 if (!URoR) return CleanupSelectors(); 221 } 222 223 SmallPtrSet<IntrinsicInst*, 32> Sels; 224 SmallPtrSet<InvokeInst*, 32> URoRInvokes; 225 FindAllCleanupSelectors(Sels); 226 FindAllURoRInvokes(URoRInvokes); 227 228 SmallPtrSet<IntrinsicInst*, 32> SelsToConvert; 229 230 for (SmallPtrSet<IntrinsicInst*, 32>::iterator 231 SI = Sels.begin(), SE = Sels.end(); SI != SE; ++SI) { 232 const BasicBlock *SelBB = (*SI)->getParent(); 233 for (SmallPtrSet<InvokeInst*, 32>::iterator 234 UI = URoRInvokes.begin(), UE = URoRInvokes.end(); UI != UE; ++UI) { 235 const BasicBlock *URoRBB = (*UI)->getParent(); 236 if (SelBB == URoRBB || DT->dominates(SelBB, URoRBB)) { 237 SelsToConvert.insert(*SI); 238 break; 239 } 240 } 241 } 242 243 bool Changed = false; 244 245 if (!SelsToConvert.empty()) { 246 // Convert all clean-up eh.selectors, which are associated with "invokes" of 247 // URoR calls, into catch-all eh.selectors. 248 Changed = true; 249 250 for (SmallPtrSet<IntrinsicInst*, 8>::iterator 251 SI = SelsToConvert.begin(), SE = SelsToConvert.end(); 252 SI != SE; ++SI) { 253 IntrinsicInst *II = *SI; 254 SmallVector<Value*, 8> Args; 255 256 // Use the exception object pointer and the personality function 257 // from the original selector. 258 Args.push_back(II->getOperand(1)); // Exception object pointer. 259 Args.push_back(II->getOperand(2)); // Personality function. 260 Args.push_back(EHCatchAllValue->getInitializer()); // Catch-all indicator. 261 262 CallInst *NewSelector = 263 CallInst::Create(SelectorIntrinsic, Args.begin(), Args.end(), 264 "eh.sel.catch.all", II); 265 266 NewSelector->setTailCall(II->isTailCall()); 267 NewSelector->setAttributes(II->getAttributes()); 268 NewSelector->setCallingConv(II->getCallingConv()); 269 270 II->replaceAllUsesWith(NewSelector); 271 II->eraseFromParent(); 272 } 273 } 274 275 Changed |= CleanupSelectors(); 276 return Changed; 277} 278 279/// NormalizeLandingPads - Normalize and discover landing pads, noting them 280/// in the LandingPads set. A landing pad is normal if the only CFG edges 281/// that end at it are unwind edges from invoke instructions. If we inlined 282/// through an invoke we could have a normal branch from the previous 283/// unwind block through to the landing pad for the original invoke. 284/// Abnormal landing pads are fixed up by redirecting all unwind edges to 285/// a new basic block which falls through to the original. 286bool DwarfEHPrepare::NormalizeLandingPads() { 287 bool Changed = false; 288 289 const MCAsmInfo *MAI = TLI->getTargetMachine().getMCAsmInfo(); 290 bool usingSjLjEH = MAI->getExceptionHandlingType() == ExceptionHandling::SjLj; 291 292 for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) { 293 TerminatorInst *TI = I->getTerminator(); 294 if (!isa<InvokeInst>(TI)) 295 continue; 296 BasicBlock *LPad = TI->getSuccessor(1); 297 // Skip landing pads that have already been normalized. 298 if (LandingPads.count(LPad)) 299 continue; 300 301 // Check that only invoke unwind edges end at the landing pad. 302 bool OnlyUnwoundTo = true; 303 bool SwitchOK = usingSjLjEH; 304 for (pred_iterator PI = pred_begin(LPad), PE = pred_end(LPad); 305 PI != PE; ++PI) { 306 TerminatorInst *PT = (*PI)->getTerminator(); 307 // The SjLj dispatch block uses a switch instruction. This is effectively 308 // an unwind edge, so we can disregard it here. There will only ever 309 // be one dispatch, however, so if there are multiple switches, one 310 // of them truly is a normal edge, not an unwind edge. 311 if (SwitchOK && isa<SwitchInst>(PT)) { 312 SwitchOK = false; 313 continue; 314 } 315 if (!isa<InvokeInst>(PT) || LPad == PT->getSuccessor(0)) { 316 OnlyUnwoundTo = false; 317 break; 318 } 319 } 320 321 if (OnlyUnwoundTo) { 322 // Only unwind edges lead to the landing pad. Remember the landing pad. 323 LandingPads.insert(LPad); 324 continue; 325 } 326 327 // At least one normal edge ends at the landing pad. Redirect the unwind 328 // edges to a new basic block which falls through into this one. 329 330 // Create the new basic block. 331 BasicBlock *NewBB = BasicBlock::Create(F->getContext(), 332 LPad->getName() + "_unwind_edge"); 333 334 // Insert it into the function right before the original landing pad. 335 LPad->getParent()->getBasicBlockList().insert(LPad, NewBB); 336 337 // Redirect unwind edges from the original landing pad to NewBB. 338 for (pred_iterator PI = pred_begin(LPad), PE = pred_end(LPad); PI != PE; ) { 339 TerminatorInst *PT = (*PI++)->getTerminator(); 340 if (isa<InvokeInst>(PT) && PT->getSuccessor(1) == LPad) 341 // Unwind to the new block. 342 PT->setSuccessor(1, NewBB); 343 } 344 345 // If there are any PHI nodes in LPad, we need to update them so that they 346 // merge incoming values from NewBB instead. 347 for (BasicBlock::iterator II = LPad->begin(); isa<PHINode>(II); ++II) { 348 PHINode *PN = cast<PHINode>(II); 349 pred_iterator PB = pred_begin(NewBB), PE = pred_end(NewBB); 350 351 // Check to see if all of the values coming in via unwind edges are the 352 // same. If so, we don't need to create a new PHI node. 353 Value *InVal = PN->getIncomingValueForBlock(*PB); 354 for (pred_iterator PI = PB; PI != PE; ++PI) { 355 if (PI != PB && InVal != PN->getIncomingValueForBlock(*PI)) { 356 InVal = 0; 357 break; 358 } 359 } 360 361 if (InVal == 0) { 362 // Different unwind edges have different values. Create a new PHI node 363 // in NewBB. 364 PHINode *NewPN = PHINode::Create(PN->getType(), PN->getName()+".unwind", 365 NewBB); 366 // Add an entry for each unwind edge, using the value from the old PHI. 367 for (pred_iterator PI = PB; PI != PE; ++PI) 368 NewPN->addIncoming(PN->getIncomingValueForBlock(*PI), *PI); 369 370 // Now use this new PHI as the common incoming value for NewBB in PN. 371 InVal = NewPN; 372 } 373 374 // Revector exactly one entry in the PHI node to come from NewBB 375 // and delete all other entries that come from unwind edges. If 376 // there are both normal and unwind edges from the same predecessor, 377 // this leaves an entry for the normal edge. 378 for (pred_iterator PI = PB; PI != PE; ++PI) 379 PN->removeIncomingValue(*PI); 380 PN->addIncoming(InVal, NewBB); 381 } 382 383 // Add a fallthrough from NewBB to the original landing pad. 384 BranchInst::Create(LPad, NewBB); 385 386 // Now update DominatorTree and DominanceFrontier analysis information. 387 if (DT) 388 DT->splitBlock(NewBB); 389 if (DF) 390 DF->splitBlock(NewBB); 391 392 // Remember the newly constructed landing pad. The original landing pad 393 // LPad is no longer a landing pad now that all unwind edges have been 394 // revectored to NewBB. 395 LandingPads.insert(NewBB); 396 ++NumLandingPadsSplit; 397 Changed = true; 398 } 399 400 return Changed; 401} 402 403/// LowerUnwinds - Turn unwind instructions into calls to _Unwind_Resume, 404/// rethrowing any previously caught exception. This will crash horribly 405/// at runtime if there is no such exception: using unwind to throw a new 406/// exception is currently not supported. 407bool DwarfEHPrepare::LowerUnwinds() { 408 SmallVector<TerminatorInst*, 16> UnwindInsts; 409 410 for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) { 411 TerminatorInst *TI = I->getTerminator(); 412 if (isa<UnwindInst>(TI)) 413 UnwindInsts.push_back(TI); 414 } 415 416 if (UnwindInsts.empty()) return false; 417 418 // Find the rewind function if we didn't already. 419 if (!RewindFunction) { 420 LLVMContext &Ctx = UnwindInsts[0]->getContext(); 421 std::vector<const Type*> 422 Params(1, Type::getInt8PtrTy(Ctx)); 423 FunctionType *FTy = FunctionType::get(Type::getVoidTy(Ctx), 424 Params, false); 425 const char *RewindName = TLI->getLibcallName(RTLIB::UNWIND_RESUME); 426 RewindFunction = F->getParent()->getOrInsertFunction(RewindName, FTy); 427 } 428 429 bool Changed = false; 430 431 for (SmallVectorImpl<TerminatorInst*>::iterator 432 I = UnwindInsts.begin(), E = UnwindInsts.end(); I != E; ++I) { 433 TerminatorInst *TI = *I; 434 435 // Replace the unwind instruction with a call to _Unwind_Resume (or the 436 // appropriate target equivalent) followed by an UnreachableInst. 437 438 // Create the call... 439 CallInst *CI = CallInst::Create(RewindFunction, 440 CreateReadOfExceptionValue(TI->getParent()), 441 "", TI); 442 CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME)); 443 // ...followed by an UnreachableInst. 444 new UnreachableInst(TI->getContext(), TI); 445 446 // Nuke the unwind instruction. 447 TI->eraseFromParent(); 448 ++NumUnwindsLowered; 449 Changed = true; 450 } 451 452 return Changed; 453} 454 455/// MoveExceptionValueCalls - Ensure that eh.exception is only ever called from 456/// landing pads by replacing calls outside of landing pads with loads from a 457/// stack temporary. Move eh.exception calls inside landing pads to the start 458/// of the landing pad (optional, but may make things simpler for later passes). 459bool DwarfEHPrepare::MoveExceptionValueCalls() { 460 // If the eh.exception intrinsic is not declared in the module then there is 461 // nothing to do. Speed up compilation by checking for this common case. 462 if (!ExceptionValueIntrinsic && 463 !F->getParent()->getFunction(Intrinsic::getName(Intrinsic::eh_exception))) 464 return false; 465 466 bool Changed = false; 467 468 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) { 469 for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E;) 470 if (IntrinsicInst *CI = dyn_cast<IntrinsicInst>(II++)) 471 if (CI->getIntrinsicID() == Intrinsic::eh_exception) { 472 if (!CI->use_empty()) { 473 Value *ExceptionValue = CreateReadOfExceptionValue(BB); 474 if (CI == ExceptionValue) { 475 // The call was at the start of a landing pad - leave it alone. 476 assert(LandingPads.count(BB) && 477 "Created eh.exception call outside landing pad!"); 478 continue; 479 } 480 CI->replaceAllUsesWith(ExceptionValue); 481 } 482 CI->eraseFromParent(); 483 ++NumExceptionValuesMoved; 484 Changed = true; 485 } 486 } 487 488 return Changed; 489} 490 491/// FinishStackTemporaries - If we introduced a stack variable to hold the 492/// exception value then initialize it in each landing pad. 493bool DwarfEHPrepare::FinishStackTemporaries() { 494 if (!ExceptionValueVar) 495 // Nothing to do. 496 return false; 497 498 bool Changed = false; 499 500 // Make sure that there is a store of the exception value at the start of 501 // each landing pad. 502 for (BBSet::iterator LI = LandingPads.begin(), LE = LandingPads.end(); 503 LI != LE; ++LI) { 504 Instruction *ExceptionValue = CreateReadOfExceptionValue(*LI); 505 Instruction *Store = new StoreInst(ExceptionValue, ExceptionValueVar); 506 Store->insertAfter(ExceptionValue); 507 Changed = true; 508 } 509 510 return Changed; 511} 512 513/// PromoteStackTemporaries - Turn any stack temporaries we introduced into 514/// registers if possible. 515bool DwarfEHPrepare::PromoteStackTemporaries() { 516 if (ExceptionValueVar && DT && DF && isAllocaPromotable(ExceptionValueVar)) { 517 // Turn the exception temporary into registers and phi nodes if possible. 518 std::vector<AllocaInst*> Allocas(1, ExceptionValueVar); 519 PromoteMemToReg(Allocas, *DT, *DF); 520 return true; 521 } 522 return false; 523} 524 525/// CreateExceptionValueCall - Insert a call to the eh.exception intrinsic at 526/// the start of the basic block (unless there already is one, in which case 527/// the existing call is returned). 528Instruction *DwarfEHPrepare::CreateExceptionValueCall(BasicBlock *BB) { 529 Instruction *Start = BB->getFirstNonPHI(); 530 // Is this a call to eh.exception? 531 if (IntrinsicInst *CI = dyn_cast<IntrinsicInst>(Start)) 532 if (CI->getIntrinsicID() == Intrinsic::eh_exception) 533 // Reuse the existing call. 534 return Start; 535 536 // Find the eh.exception intrinsic if we didn't already. 537 if (!ExceptionValueIntrinsic) 538 ExceptionValueIntrinsic = Intrinsic::getDeclaration(F->getParent(), 539 Intrinsic::eh_exception); 540 541 // Create the call. 542 return CallInst::Create(ExceptionValueIntrinsic, "eh.value.call", Start); 543} 544 545/// CreateValueLoad - Insert a load of the exception value stack variable 546/// (creating it if necessary) at the start of the basic block (unless 547/// there already is a load, in which case the existing load is returned). 548Instruction *DwarfEHPrepare::CreateValueLoad(BasicBlock *BB) { 549 Instruction *Start = BB->getFirstNonPHI(); 550 // Is this a load of the exception temporary? 551 if (ExceptionValueVar) 552 if (LoadInst* LI = dyn_cast<LoadInst>(Start)) 553 if (LI->getPointerOperand() == ExceptionValueVar) 554 // Reuse the existing load. 555 return Start; 556 557 // Create the temporary if we didn't already. 558 if (!ExceptionValueVar) { 559 ExceptionValueVar = new AllocaInst(PointerType::getUnqual( 560 Type::getInt8Ty(BB->getContext())), "eh.value", F->begin()->begin()); 561 ++NumStackTempsIntroduced; 562 } 563 564 // Load the value. 565 return new LoadInst(ExceptionValueVar, "eh.value.load", Start); 566} 567 568bool DwarfEHPrepare::runOnFunction(Function &Fn) { 569 bool Changed = false; 570 571 // Initialize internal state. 572 DT = getAnalysisIfAvailable<DominatorTree>(); 573 DF = getAnalysisIfAvailable<DominanceFrontier>(); 574 ExceptionValueVar = 0; 575 F = &Fn; 576 577 // Ensure that only unwind edges end at landing pads (a landing pad is a 578 // basic block where an invoke unwind edge ends). 579 Changed |= NormalizeLandingPads(); 580 581 // Turn unwind instructions into libcalls. 582 Changed |= LowerUnwinds(); 583 584 // TODO: Move eh.selector calls to landing pads and combine them. 585 586 // Move eh.exception calls to landing pads. 587 Changed |= MoveExceptionValueCalls(); 588 589 // Initialize any stack temporaries we introduced. 590 Changed |= FinishStackTemporaries(); 591 592 // Turn any stack temporaries into registers if possible. 593 if (!CompileFast) 594 Changed |= PromoteStackTemporaries(); 595 596 Changed |= HandleURoRInvokes(); 597 598 LandingPads.clear(); 599 600 return Changed; 601} 602