1 //===-- WinEHPrepare - Prepare exception handling for code generation ---===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This pass lowers LLVM IR exception handling into something closer to what the
11 // backend wants for functions using a personality function from a runtime
12 // provided by MSVC. Functions with other personality functions are left alone
13 // and may be prepared by other passes. In particular, all supported MSVC
14 // personality functions require cleanup code to be outlined, and the C++
15 // personality requires catch handler code to be outlined.
17 //===----------------------------------------------------------------------===//
19 #include "llvm/CodeGen/Passes.h"
20 #include "llvm/ADT/DenseMap.h"
21 #include "llvm/ADT/MapVector.h"
22 #include "llvm/ADT/STLExtras.h"
23 #include "llvm/Analysis/CFG.h"
24 #include "llvm/Analysis/EHPersonalities.h"
25 #include "llvm/CodeGen/MachineBasicBlock.h"
26 #include "llvm/CodeGen/WinEHFuncInfo.h"
27 #include "llvm/IR/Verifier.h"
28 #include "llvm/MC/MCSymbol.h"
29 #include "llvm/Pass.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/Support/raw_ostream.h"
32 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
33 #include "llvm/Transforms/Utils/Cloning.h"
34 #include "llvm/Transforms/Utils/Local.h"
35 #include "llvm/Transforms/Utils/SSAUpdater.h"
39 #define DEBUG_TYPE "winehprepare"
41 static cl::opt<bool> DisableDemotion(
42 "disable-demotion", cl::Hidden,
44 "Clone multicolor basic blocks but do not demote cross funclet values"),
47 static cl::opt<bool> DisableCleanups(
48 "disable-cleanups", cl::Hidden,
49 cl::desc("Do not remove implausible terminators or other similar cleanups"),
54 class WinEHPrepare : public FunctionPass {
56 static char ID; // Pass identification, replacement for typeid.
57 WinEHPrepare(const TargetMachine *TM = nullptr) : FunctionPass(ID) {}
59 bool runOnFunction(Function &Fn) override;
61 bool doFinalization(Module &M) override;
63 void getAnalysisUsage(AnalysisUsage &AU) const override;
65 const char *getPassName() const override {
66 return "Windows exception handling preparation";
70 void insertPHIStores(PHINode *OriginalPHI, AllocaInst *SpillSlot);
72 insertPHIStore(BasicBlock *PredBlock, Value *PredVal, AllocaInst *SpillSlot,
73 SmallVectorImpl<std::pair<BasicBlock *, Value *>> &Worklist);
74 AllocaInst *insertPHILoads(PHINode *PN, Function &F);
75 void replaceUseWithLoad(Value *V, Use &U, AllocaInst *&SpillSlot,
76 DenseMap<BasicBlock *, Value *> &Loads, Function &F);
77 bool prepareExplicitEH(Function &F);
78 void colorFunclets(Function &F);
80 void demotePHIsOnFunclets(Function &F);
81 void cloneCommonBlocks(Function &F);
82 void removeImplausibleInstructions(Function &F);
83 void cleanupPreparedFunclets(Function &F);
84 void verifyPreparedFunclets(Function &F);
86 // All fields are reset by runOnFunction.
87 EHPersonality Personality = EHPersonality::Unknown;
89 DenseMap<BasicBlock *, ColorVector> BlockColors;
90 MapVector<BasicBlock *, std::vector<BasicBlock *>> FuncletBlocks;
93 } // end anonymous namespace
95 char WinEHPrepare::ID = 0;
96 INITIALIZE_TM_PASS(WinEHPrepare, "winehprepare", "Prepare Windows exceptions",
99 FunctionPass *llvm::createWinEHPass(const TargetMachine *TM) {
100 return new WinEHPrepare(TM);
103 bool WinEHPrepare::runOnFunction(Function &Fn) {
104 if (!Fn.hasPersonalityFn())
107 // Classify the personality to see what kind of preparation we need.
108 Personality = classifyEHPersonality(Fn.getPersonalityFn());
110 // Do nothing if this is not a funclet-based personality.
111 if (!isFuncletEHPersonality(Personality))
114 return prepareExplicitEH(Fn);
117 bool WinEHPrepare::doFinalization(Module &M) { return false; }
119 void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {}
121 static int addUnwindMapEntry(WinEHFuncInfo &FuncInfo, int ToState,
122 const BasicBlock *BB) {
123 CxxUnwindMapEntry UME;
124 UME.ToState = ToState;
126 FuncInfo.CxxUnwindMap.push_back(UME);
127 return FuncInfo.getLastStateNumber();
130 static void addTryBlockMapEntry(WinEHFuncInfo &FuncInfo, int TryLow,
131 int TryHigh, int CatchHigh,
132 ArrayRef<const CatchPadInst *> Handlers) {
133 WinEHTryBlockMapEntry TBME;
134 TBME.TryLow = TryLow;
135 TBME.TryHigh = TryHigh;
136 TBME.CatchHigh = CatchHigh;
137 assert(TBME.TryLow <= TBME.TryHigh);
138 for (const CatchPadInst *CPI : Handlers) {
140 Constant *TypeInfo = cast<Constant>(CPI->getArgOperand(0));
141 if (TypeInfo->isNullValue())
142 HT.TypeDescriptor = nullptr;
144 HT.TypeDescriptor = cast<GlobalVariable>(TypeInfo->stripPointerCasts());
145 HT.Adjectives = cast<ConstantInt>(CPI->getArgOperand(1))->getZExtValue();
146 HT.Handler = CPI->getParent();
148 dyn_cast<AllocaInst>(CPI->getArgOperand(2)->stripPointerCasts()))
149 HT.CatchObj.Alloca = AI;
151 HT.CatchObj.Alloca = nullptr;
152 TBME.HandlerArray.push_back(HT);
154 FuncInfo.TryBlockMap.push_back(TBME);
157 static BasicBlock *getCleanupRetUnwindDest(const CleanupPadInst *CleanupPad) {
158 for (const User *U : CleanupPad->users())
159 if (const auto *CRI = dyn_cast<CleanupReturnInst>(U))
160 return CRI->getUnwindDest();
164 static void calculateStateNumbersForInvokes(const Function *Fn,
165 WinEHFuncInfo &FuncInfo) {
166 auto *F = const_cast<Function *>(Fn);
167 DenseMap<BasicBlock *, ColorVector> BlockColors = colorEHFunclets(*F);
168 for (BasicBlock &BB : *F) {
169 auto *II = dyn_cast<InvokeInst>(BB.getTerminator());
173 auto &BBColors = BlockColors[&BB];
174 assert(BBColors.size() == 1 && "multi-color BB not removed by preparation");
175 BasicBlock *FuncletEntryBB = BBColors.front();
177 BasicBlock *FuncletUnwindDest;
179 dyn_cast<FuncletPadInst>(FuncletEntryBB->getFirstNonPHI());
180 assert(FuncletPad || FuncletEntryBB == &Fn->getEntryBlock());
182 FuncletUnwindDest = nullptr;
183 else if (auto *CatchPad = dyn_cast<CatchPadInst>(FuncletPad))
184 FuncletUnwindDest = CatchPad->getCatchSwitch()->getUnwindDest();
185 else if (auto *CleanupPad = dyn_cast<CleanupPadInst>(FuncletPad))
186 FuncletUnwindDest = getCleanupRetUnwindDest(CleanupPad);
188 llvm_unreachable("unexpected funclet pad!");
190 BasicBlock *InvokeUnwindDest = II->getUnwindDest();
192 if (FuncletUnwindDest == InvokeUnwindDest) {
193 auto BaseStateI = FuncInfo.FuncletBaseStateMap.find(FuncletPad);
194 if (BaseStateI != FuncInfo.FuncletBaseStateMap.end())
195 BaseState = BaseStateI->second;
198 if (BaseState != -1) {
199 FuncInfo.InvokeStateMap[II] = BaseState;
201 Instruction *PadInst = InvokeUnwindDest->getFirstNonPHI();
202 assert(FuncInfo.EHPadStateMap.count(PadInst) && "EH Pad has no state!");
203 FuncInfo.InvokeStateMap[II] = FuncInfo.EHPadStateMap[PadInst];
208 // Given BB which ends in an unwind edge, return the EHPad that this BB belongs
209 // to. If the unwind edge came from an invoke, return null.
210 static const BasicBlock *getEHPadFromPredecessor(const BasicBlock *BB,
212 const TerminatorInst *TI = BB->getTerminator();
213 if (isa<InvokeInst>(TI))
215 if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(TI)) {
216 if (CatchSwitch->getParentPad() != ParentPad)
220 assert(!TI->isEHPad() && "unexpected EHPad!");
221 auto *CleanupPad = cast<CleanupReturnInst>(TI)->getCleanupPad();
222 if (CleanupPad->getParentPad() != ParentPad)
224 return CleanupPad->getParent();
227 static void calculateCXXStateNumbers(WinEHFuncInfo &FuncInfo,
228 const Instruction *FirstNonPHI,
230 const BasicBlock *BB = FirstNonPHI->getParent();
231 assert(BB->isEHPad() && "not a funclet!");
233 if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(FirstNonPHI)) {
234 assert(FuncInfo.EHPadStateMap.count(CatchSwitch) == 0 &&
235 "shouldn't revist catch funclets!");
237 SmallVector<const CatchPadInst *, 2> Handlers;
238 for (const BasicBlock *CatchPadBB : CatchSwitch->handlers()) {
239 auto *CatchPad = cast<CatchPadInst>(CatchPadBB->getFirstNonPHI());
240 Handlers.push_back(CatchPad);
242 int TryLow = addUnwindMapEntry(FuncInfo, ParentState, nullptr);
243 FuncInfo.EHPadStateMap[CatchSwitch] = TryLow;
244 for (const BasicBlock *PredBlock : predecessors(BB))
245 if ((PredBlock = getEHPadFromPredecessor(PredBlock,
246 CatchSwitch->getParentPad())))
247 calculateCXXStateNumbers(FuncInfo, PredBlock->getFirstNonPHI(),
249 int CatchLow = addUnwindMapEntry(FuncInfo, ParentState, nullptr);
251 // catchpads are separate funclets in C++ EH due to the way rethrow works.
252 int TryHigh = CatchLow - 1;
253 for (const auto *CatchPad : Handlers) {
254 FuncInfo.FuncletBaseStateMap[CatchPad] = CatchLow;
255 for (const User *U : CatchPad->users()) {
256 const auto *UserI = cast<Instruction>(U);
257 if (auto *InnerCatchSwitch = dyn_cast<CatchSwitchInst>(UserI))
258 if (InnerCatchSwitch->getUnwindDest() == CatchSwitch->getUnwindDest())
259 calculateCXXStateNumbers(FuncInfo, UserI, CatchLow);
260 if (auto *InnerCleanupPad = dyn_cast<CleanupPadInst>(UserI)) {
261 BasicBlock *UnwindDest = getCleanupRetUnwindDest(InnerCleanupPad);
262 // If a nested cleanup pad reports a null unwind destination and the
263 // enclosing catch pad doesn't it must be post-dominated by an
264 // unreachable instruction.
265 if (!UnwindDest || UnwindDest == CatchSwitch->getUnwindDest())
266 calculateCXXStateNumbers(FuncInfo, UserI, CatchLow);
270 int CatchHigh = FuncInfo.getLastStateNumber();
271 addTryBlockMapEntry(FuncInfo, TryLow, TryHigh, CatchHigh, Handlers);
272 DEBUG(dbgs() << "TryLow[" << BB->getName() << "]: " << TryLow << '\n');
273 DEBUG(dbgs() << "TryHigh[" << BB->getName() << "]: " << TryHigh << '\n');
274 DEBUG(dbgs() << "CatchHigh[" << BB->getName() << "]: " << CatchHigh
277 auto *CleanupPad = cast<CleanupPadInst>(FirstNonPHI);
279 // It's possible for a cleanup to be visited twice: it might have multiple
280 // cleanupret instructions.
281 if (FuncInfo.EHPadStateMap.count(CleanupPad))
284 int CleanupState = addUnwindMapEntry(FuncInfo, ParentState, BB);
285 FuncInfo.EHPadStateMap[CleanupPad] = CleanupState;
286 DEBUG(dbgs() << "Assigning state #" << CleanupState << " to BB "
287 << BB->getName() << '\n');
288 for (const BasicBlock *PredBlock : predecessors(BB)) {
289 if ((PredBlock = getEHPadFromPredecessor(PredBlock,
290 CleanupPad->getParentPad()))) {
291 calculateCXXStateNumbers(FuncInfo, PredBlock->getFirstNonPHI(),
295 for (const User *U : CleanupPad->users()) {
296 const auto *UserI = cast<Instruction>(U);
297 if (UserI->isEHPad())
298 report_fatal_error("Cleanup funclets for the MSVC++ personality cannot "
299 "contain exceptional actions");
304 static int addSEHExcept(WinEHFuncInfo &FuncInfo, int ParentState,
305 const Function *Filter, const BasicBlock *Handler) {
306 SEHUnwindMapEntry Entry;
307 Entry.ToState = ParentState;
308 Entry.IsFinally = false;
309 Entry.Filter = Filter;
310 Entry.Handler = Handler;
311 FuncInfo.SEHUnwindMap.push_back(Entry);
312 return FuncInfo.SEHUnwindMap.size() - 1;
315 static int addSEHFinally(WinEHFuncInfo &FuncInfo, int ParentState,
316 const BasicBlock *Handler) {
317 SEHUnwindMapEntry Entry;
318 Entry.ToState = ParentState;
319 Entry.IsFinally = true;
320 Entry.Filter = nullptr;
321 Entry.Handler = Handler;
322 FuncInfo.SEHUnwindMap.push_back(Entry);
323 return FuncInfo.SEHUnwindMap.size() - 1;
326 static void calculateSEHStateNumbers(WinEHFuncInfo &FuncInfo,
327 const Instruction *FirstNonPHI,
329 const BasicBlock *BB = FirstNonPHI->getParent();
330 assert(BB->isEHPad() && "no a funclet!");
332 if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(FirstNonPHI)) {
333 assert(FuncInfo.EHPadStateMap.count(CatchSwitch) == 0 &&
334 "shouldn't revist catch funclets!");
336 // Extract the filter function and the __except basic block and create a
338 assert(CatchSwitch->getNumHandlers() == 1 &&
339 "SEH doesn't have multiple handlers per __try");
340 const auto *CatchPad =
341 cast<CatchPadInst>((*CatchSwitch->handler_begin())->getFirstNonPHI());
342 const BasicBlock *CatchPadBB = CatchPad->getParent();
343 const Constant *FilterOrNull =
344 cast<Constant>(CatchPad->getArgOperand(0)->stripPointerCasts());
345 const Function *Filter = dyn_cast<Function>(FilterOrNull);
346 assert((Filter || FilterOrNull->isNullValue()) &&
347 "unexpected filter value");
348 int TryState = addSEHExcept(FuncInfo, ParentState, Filter, CatchPadBB);
350 // Everything in the __try block uses TryState as its parent state.
351 FuncInfo.EHPadStateMap[CatchSwitch] = TryState;
352 DEBUG(dbgs() << "Assigning state #" << TryState << " to BB "
353 << CatchPadBB->getName() << '\n');
354 for (const BasicBlock *PredBlock : predecessors(BB))
355 if ((PredBlock = getEHPadFromPredecessor(PredBlock,
356 CatchSwitch->getParentPad())))
357 calculateSEHStateNumbers(FuncInfo, PredBlock->getFirstNonPHI(),
360 // Everything in the __except block unwinds to ParentState, just like code
361 // outside the __try.
362 for (const User *U : CatchPad->users()) {
363 const auto *UserI = cast<Instruction>(U);
364 if (auto *InnerCatchSwitch = dyn_cast<CatchSwitchInst>(UserI))
365 if (InnerCatchSwitch->getUnwindDest() == CatchSwitch->getUnwindDest())
366 calculateSEHStateNumbers(FuncInfo, UserI, ParentState);
367 if (auto *InnerCleanupPad = dyn_cast<CleanupPadInst>(UserI)) {
368 BasicBlock *UnwindDest = getCleanupRetUnwindDest(InnerCleanupPad);
369 // If a nested cleanup pad reports a null unwind destination and the
370 // enclosing catch pad doesn't it must be post-dominated by an
371 // unreachable instruction.
372 if (!UnwindDest || UnwindDest == CatchSwitch->getUnwindDest())
373 calculateSEHStateNumbers(FuncInfo, UserI, ParentState);
377 auto *CleanupPad = cast<CleanupPadInst>(FirstNonPHI);
379 // It's possible for a cleanup to be visited twice: it might have multiple
380 // cleanupret instructions.
381 if (FuncInfo.EHPadStateMap.count(CleanupPad))
384 int CleanupState = addSEHFinally(FuncInfo, ParentState, BB);
385 FuncInfo.EHPadStateMap[CleanupPad] = CleanupState;
386 DEBUG(dbgs() << "Assigning state #" << CleanupState << " to BB "
387 << BB->getName() << '\n');
388 for (const BasicBlock *PredBlock : predecessors(BB))
390 getEHPadFromPredecessor(PredBlock, CleanupPad->getParentPad())))
391 calculateSEHStateNumbers(FuncInfo, PredBlock->getFirstNonPHI(),
393 for (const User *U : CleanupPad->users()) {
394 const auto *UserI = cast<Instruction>(U);
395 if (UserI->isEHPad())
396 report_fatal_error("Cleanup funclets for the SEH personality cannot "
397 "contain exceptional actions");
402 static bool isTopLevelPadForMSVC(const Instruction *EHPad) {
403 if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(EHPad))
404 return isa<ConstantTokenNone>(CatchSwitch->getParentPad()) &&
405 CatchSwitch->unwindsToCaller();
406 if (auto *CleanupPad = dyn_cast<CleanupPadInst>(EHPad))
407 return isa<ConstantTokenNone>(CleanupPad->getParentPad()) &&
408 getCleanupRetUnwindDest(CleanupPad) == nullptr;
409 if (isa<CatchPadInst>(EHPad))
411 llvm_unreachable("unexpected EHPad!");
414 void llvm::calculateSEHStateNumbers(const Function *Fn,
415 WinEHFuncInfo &FuncInfo) {
416 // Don't compute state numbers twice.
417 if (!FuncInfo.SEHUnwindMap.empty())
420 for (const BasicBlock &BB : *Fn) {
423 const Instruction *FirstNonPHI = BB.getFirstNonPHI();
424 if (!isTopLevelPadForMSVC(FirstNonPHI))
426 ::calculateSEHStateNumbers(FuncInfo, FirstNonPHI, -1);
429 calculateStateNumbersForInvokes(Fn, FuncInfo);
432 void llvm::calculateWinCXXEHStateNumbers(const Function *Fn,
433 WinEHFuncInfo &FuncInfo) {
434 // Return if it's already been done.
435 if (!FuncInfo.EHPadStateMap.empty())
438 for (const BasicBlock &BB : *Fn) {
441 const Instruction *FirstNonPHI = BB.getFirstNonPHI();
442 if (!isTopLevelPadForMSVC(FirstNonPHI))
444 calculateCXXStateNumbers(FuncInfo, FirstNonPHI, -1);
447 calculateStateNumbersForInvokes(Fn, FuncInfo);
450 static int addClrEHHandler(WinEHFuncInfo &FuncInfo, int HandlerParentState,
451 int TryParentState, ClrHandlerType HandlerType,
452 uint32_t TypeToken, const BasicBlock *Handler) {
453 ClrEHUnwindMapEntry Entry;
454 Entry.HandlerParentState = HandlerParentState;
455 Entry.TryParentState = TryParentState;
456 Entry.Handler = Handler;
457 Entry.HandlerType = HandlerType;
458 Entry.TypeToken = TypeToken;
459 FuncInfo.ClrEHUnwindMap.push_back(Entry);
460 return FuncInfo.ClrEHUnwindMap.size() - 1;
463 void llvm::calculateClrEHStateNumbers(const Function *Fn,
464 WinEHFuncInfo &FuncInfo) {
465 // Return if it's already been done.
466 if (!FuncInfo.EHPadStateMap.empty())
469 // This numbering assigns one state number to each catchpad and cleanuppad.
470 // It also computes two tree-like relations over states:
471 // 1) Each state has a "HandlerParentState", which is the state of the next
472 // outer handler enclosing this state's handler (same as nearest ancestor
473 // per the ParentPad linkage on EH pads, but skipping over catchswitches).
474 // 2) Each state has a "TryParentState", which:
475 // a) for a catchpad that's not the last handler on its catchswitch, is
476 // the state of the next catchpad on that catchswitch
477 // b) for all other pads, is the state of the pad whose try region is the
478 // next outer try region enclosing this state's try region. The "try
479 // regions are not present as such in the IR, but will be inferred
480 // based on the placement of invokes and pads which reach each other
481 // by exceptional exits
482 // Catchswitches do not get their own states, but each gets mapped to the
483 // state of its first catchpad.
485 // Step one: walk down from outermost to innermost funclets, assigning each
486 // catchpad and cleanuppad a state number. Add an entry to the
487 // ClrEHUnwindMap for each state, recording its HandlerParentState and
488 // handler attributes. Record the TryParentState as well for each catchpad
489 // that's not the last on its catchswitch, but initialize all other entries'
490 // TryParentStates to a sentinel -1 value that the next pass will update.
492 // Seed a worklist with pads that have no parent.
493 SmallVector<std::pair<const Instruction *, int>, 8> Worklist;
494 for (const BasicBlock &BB : *Fn) {
495 const Instruction *FirstNonPHI = BB.getFirstNonPHI();
496 const Value *ParentPad;
497 if (const auto *CPI = dyn_cast<CleanupPadInst>(FirstNonPHI))
498 ParentPad = CPI->getParentPad();
499 else if (const auto *CSI = dyn_cast<CatchSwitchInst>(FirstNonPHI))
500 ParentPad = CSI->getParentPad();
503 if (isa<ConstantTokenNone>(ParentPad))
504 Worklist.emplace_back(FirstNonPHI, -1);
507 // Use the worklist to visit all pads, from outer to inner. Record
508 // HandlerParentState for all pads. Record TryParentState only for catchpads
509 // that aren't the last on their catchswitch (setting all other entries'
510 // TryParentStates to an initial value of -1). This loop is also responsible
511 // for setting the EHPadStateMap entry for all catchpads, cleanuppads, and
513 while (!Worklist.empty()) {
514 const Instruction *Pad;
515 int HandlerParentState;
516 std::tie(Pad, HandlerParentState) = Worklist.pop_back_val();
518 if (const auto *Cleanup = dyn_cast<CleanupPadInst>(Pad)) {
519 // Create the entry for this cleanup with the appropriate handler
520 // properties. Finaly and fault handlers are distinguished by arity.
521 ClrHandlerType HandlerType =
522 (Cleanup->getNumArgOperands() ? ClrHandlerType::Fault
523 : ClrHandlerType::Finally);
524 int CleanupState = addClrEHHandler(FuncInfo, HandlerParentState, -1,
525 HandlerType, 0, Pad->getParent());
526 // Queue any child EH pads on the worklist.
527 for (const User *U : Cleanup->users())
528 if (const auto *I = dyn_cast<Instruction>(U))
530 Worklist.emplace_back(I, CleanupState);
531 // Remember this pad's state.
532 FuncInfo.EHPadStateMap[Cleanup] = CleanupState;
534 // Walk the handlers of this catchswitch in reverse order since all but
535 // the last need to set the following one as its TryParentState.
536 const auto *CatchSwitch = cast<CatchSwitchInst>(Pad);
537 int CatchState = -1, FollowerState = -1;
538 SmallVector<const BasicBlock *, 4> CatchBlocks(CatchSwitch->handlers());
539 for (auto CBI = CatchBlocks.rbegin(), CBE = CatchBlocks.rend();
540 CBI != CBE; ++CBI, FollowerState = CatchState) {
541 const BasicBlock *CatchBlock = *CBI;
542 // Create the entry for this catch with the appropriate handler
544 const auto *Catch = cast<CatchPadInst>(CatchBlock->getFirstNonPHI());
545 uint32_t TypeToken = static_cast<uint32_t>(
546 cast<ConstantInt>(Catch->getArgOperand(0))->getZExtValue());
548 addClrEHHandler(FuncInfo, HandlerParentState, FollowerState,
549 ClrHandlerType::Catch, TypeToken, CatchBlock);
550 // Queue any child EH pads on the worklist.
551 for (const User *U : Catch->users())
552 if (const auto *I = dyn_cast<Instruction>(U))
554 Worklist.emplace_back(I, CatchState);
555 // Remember this catch's state.
556 FuncInfo.EHPadStateMap[Catch] = CatchState;
558 // Associate the catchswitch with the state of its first catch.
559 assert(CatchSwitch->getNumHandlers());
560 FuncInfo.EHPadStateMap[CatchSwitch] = CatchState;
564 // Step two: record the TryParentState of each state. For cleanuppads that
565 // don't have cleanuprets, we may need to infer this from their child pads,
566 // so visit pads in descendant-most to ancestor-most order.
567 for (auto Entry = FuncInfo.ClrEHUnwindMap.rbegin(),
568 End = FuncInfo.ClrEHUnwindMap.rend();
569 Entry != End; ++Entry) {
570 const Instruction *Pad =
571 Entry->Handler.get<const BasicBlock *>()->getFirstNonPHI();
572 // For most pads, the TryParentState is the state associated with the
573 // unwind dest of exceptional exits from it.
574 const BasicBlock *UnwindDest;
575 if (const auto *Catch = dyn_cast<CatchPadInst>(Pad)) {
576 // If a catch is not the last in its catchswitch, its TryParentState is
577 // the state associated with the next catch in the switch, even though
578 // that's not the unwind dest of exceptions escaping the catch. Those
579 // cases were already assigned a TryParentState in the first pass, so
581 if (Entry->TryParentState != -1)
583 // Otherwise, get the unwind dest from the catchswitch.
584 UnwindDest = Catch->getCatchSwitch()->getUnwindDest();
586 const auto *Cleanup = cast<CleanupPadInst>(Pad);
587 UnwindDest = nullptr;
588 for (const User *U : Cleanup->users()) {
589 if (auto *CleanupRet = dyn_cast<CleanupReturnInst>(U)) {
590 // Common and unambiguous case -- cleanupret indicates cleanup's
592 UnwindDest = CleanupRet->getUnwindDest();
596 // Get an unwind dest for the user
597 const BasicBlock *UserUnwindDest = nullptr;
598 if (auto *Invoke = dyn_cast<InvokeInst>(U)) {
599 UserUnwindDest = Invoke->getUnwindDest();
600 } else if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(U)) {
601 UserUnwindDest = CatchSwitch->getUnwindDest();
602 } else if (auto *ChildCleanup = dyn_cast<CleanupPadInst>(U)) {
603 int UserState = FuncInfo.EHPadStateMap[ChildCleanup];
604 int UserUnwindState =
605 FuncInfo.ClrEHUnwindMap[UserState].TryParentState;
606 if (UserUnwindState != -1)
607 UserUnwindDest = FuncInfo.ClrEHUnwindMap[UserUnwindState]
608 .Handler.get<const BasicBlock *>();
611 // Not having an unwind dest for this user might indicate that it
612 // doesn't unwind, so can't be taken as proof that the cleanup itself
613 // may unwind to caller (see e.g. SimplifyUnreachable and
614 // RemoveUnwindEdge).
618 // Now we have an unwind dest for the user, but we need to see if it
619 // unwinds all the way out of the cleanup or if it stays within it.
620 const Instruction *UserUnwindPad = UserUnwindDest->getFirstNonPHI();
621 const Value *UserUnwindParent;
622 if (auto *CSI = dyn_cast<CatchSwitchInst>(UserUnwindPad))
623 UserUnwindParent = CSI->getParentPad();
626 cast<CleanupPadInst>(UserUnwindPad)->getParentPad();
628 // The unwind stays within the cleanup iff it targets a child of the
630 if (UserUnwindParent == Cleanup)
633 // This unwind exits the cleanup, so its dest is the cleanup's dest.
634 UnwindDest = UserUnwindDest;
639 // Record the state of the unwind dest as the TryParentState.
642 // If UnwindDest is null at this point, either the pad in question can
643 // be exited by unwind to caller, or it cannot be exited by unwind. In
644 // either case, reporting such cases as unwinding to caller is correct.
645 // This can lead to EH tables that "look strange" -- if this pad's is in
646 // a parent funclet which has other children that do unwind to an enclosing
647 // pad, the try region for this pad will be missing the "duplicate" EH
648 // clause entries that you'd expect to see covering the whole parent. That
649 // should be benign, since the unwind never actually happens. If it were
650 // an issue, we could add a subsequent pass that pushes unwind dests down
651 // from parents that have them to children that appear to unwind to caller.
653 UnwindDestState = -1;
655 UnwindDestState = FuncInfo.EHPadStateMap[UnwindDest->getFirstNonPHI()];
658 Entry->TryParentState = UnwindDestState;
661 // Step three: transfer information from pads to invokes.
662 calculateStateNumbersForInvokes(Fn, FuncInfo);
665 void WinEHPrepare::colorFunclets(Function &F) {
666 BlockColors = colorEHFunclets(F);
668 // Invert the map from BB to colors to color to BBs.
669 for (BasicBlock &BB : F) {
670 ColorVector &Colors = BlockColors[&BB];
671 for (BasicBlock *Color : Colors)
672 FuncletBlocks[Color].push_back(&BB);
676 void WinEHPrepare::demotePHIsOnFunclets(Function &F) {
677 // Strip PHI nodes off of EH pads.
678 SmallVector<PHINode *, 16> PHINodes;
679 for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) {
680 BasicBlock *BB = &*FI++;
683 for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
684 Instruction *I = &*BI++;
685 auto *PN = dyn_cast<PHINode>(I);
686 // Stop at the first non-PHI.
690 AllocaInst *SpillSlot = insertPHILoads(PN, F);
692 insertPHIStores(PN, SpillSlot);
694 PHINodes.push_back(PN);
698 for (auto *PN : PHINodes) {
699 // There may be lingering uses on other EH PHIs being removed
700 PN->replaceAllUsesWith(UndefValue::get(PN->getType()));
701 PN->eraseFromParent();
705 void WinEHPrepare::cloneCommonBlocks(Function &F) {
706 // We need to clone all blocks which belong to multiple funclets. Values are
707 // remapped throughout the funclet to propogate both the new instructions
708 // *and* the new basic blocks themselves.
709 for (auto &Funclets : FuncletBlocks) {
710 BasicBlock *FuncletPadBB = Funclets.first;
711 std::vector<BasicBlock *> &BlocksInFunclet = Funclets.second;
713 if (FuncletPadBB == &F.getEntryBlock())
714 FuncletToken = ConstantTokenNone::get(F.getContext());
716 FuncletToken = FuncletPadBB->getFirstNonPHI();
718 std::vector<std::pair<BasicBlock *, BasicBlock *>> Orig2Clone;
719 ValueToValueMapTy VMap;
720 for (BasicBlock *BB : BlocksInFunclet) {
721 ColorVector &ColorsForBB = BlockColors[BB];
722 // We don't need to do anything if the block is monochromatic.
723 size_t NumColorsForBB = ColorsForBB.size();
724 if (NumColorsForBB == 1)
727 DEBUG_WITH_TYPE("winehprepare-coloring",
728 dbgs() << " Cloning block \'" << BB->getName()
729 << "\' for funclet \'" << FuncletPadBB->getName()
732 // Create a new basic block and copy instructions into it!
734 CloneBasicBlock(BB, VMap, Twine(".for.", FuncletPadBB->getName()));
735 // Insert the clone immediately after the original to ensure determinism
736 // and to keep the same relative ordering of any funclet's blocks.
737 CBB->insertInto(&F, BB->getNextNode());
739 // Add basic block mapping.
742 // Record delta operations that we need to perform to our color mappings.
743 Orig2Clone.emplace_back(BB, CBB);
746 // If nothing was cloned, we're done cloning in this funclet.
747 if (Orig2Clone.empty())
750 // Update our color mappings to reflect that one block has lost a color and
751 // another has gained a color.
752 for (auto &BBMapping : Orig2Clone) {
753 BasicBlock *OldBlock = BBMapping.first;
754 BasicBlock *NewBlock = BBMapping.second;
756 BlocksInFunclet.push_back(NewBlock);
757 ColorVector &NewColors = BlockColors[NewBlock];
758 assert(NewColors.empty() && "A new block should only have one color!");
759 NewColors.push_back(FuncletPadBB);
761 DEBUG_WITH_TYPE("winehprepare-coloring",
762 dbgs() << " Assigned color \'" << FuncletPadBB->getName()
763 << "\' to block \'" << NewBlock->getName()
766 BlocksInFunclet.erase(
767 std::remove(BlocksInFunclet.begin(), BlocksInFunclet.end(), OldBlock),
768 BlocksInFunclet.end());
769 ColorVector &OldColors = BlockColors[OldBlock];
771 std::remove(OldColors.begin(), OldColors.end(), FuncletPadBB),
774 DEBUG_WITH_TYPE("winehprepare-coloring",
775 dbgs() << " Removed color \'" << FuncletPadBB->getName()
776 << "\' from block \'" << OldBlock->getName()
780 // Loop over all of the instructions in this funclet, fixing up operand
781 // references as we go. This uses VMap to do all the hard work.
782 for (BasicBlock *BB : BlocksInFunclet)
783 // Loop over all instructions, fixing each one as we find it...
784 for (Instruction &I : *BB)
785 RemapInstruction(&I, VMap,
786 RF_IgnoreMissingEntries | RF_NoModuleLevelChanges);
788 // Catchrets targeting cloned blocks need to be updated separately from
789 // the loop above because they are not in the current funclet.
790 SmallVector<CatchReturnInst *, 2> FixupCatchrets;
791 for (auto &BBMapping : Orig2Clone) {
792 BasicBlock *OldBlock = BBMapping.first;
793 BasicBlock *NewBlock = BBMapping.second;
795 FixupCatchrets.clear();
796 for (BasicBlock *Pred : predecessors(OldBlock))
797 if (auto *CatchRet = dyn_cast<CatchReturnInst>(Pred->getTerminator()))
798 if (CatchRet->getParentPad() == FuncletToken)
799 FixupCatchrets.push_back(CatchRet);
801 for (CatchReturnInst *CatchRet : FixupCatchrets)
802 CatchRet->setSuccessor(NewBlock);
805 auto UpdatePHIOnClonedBlock = [&](PHINode *PN, bool IsForOldBlock) {
806 unsigned NumPreds = PN->getNumIncomingValues();
807 for (unsigned PredIdx = 0, PredEnd = NumPreds; PredIdx != PredEnd;
809 BasicBlock *IncomingBlock = PN->getIncomingBlock(PredIdx);
810 bool EdgeTargetsFunclet;
812 dyn_cast<CatchReturnInst>(IncomingBlock->getTerminator())) {
813 EdgeTargetsFunclet = (CRI->getParentPad() == FuncletToken);
815 ColorVector &IncomingColors = BlockColors[IncomingBlock];
816 assert(!IncomingColors.empty() && "Block not colored!");
817 assert((IncomingColors.size() == 1 ||
818 llvm::all_of(IncomingColors,
819 [&](BasicBlock *Color) {
820 return Color != FuncletPadBB;
822 "Cloning should leave this funclet's blocks monochromatic");
823 EdgeTargetsFunclet = (IncomingColors.front() == FuncletPadBB);
825 if (IsForOldBlock != EdgeTargetsFunclet)
827 PN->removeIncomingValue(IncomingBlock, /*DeletePHIIfEmpty=*/false);
828 // Revisit the next entry.
834 for (auto &BBMapping : Orig2Clone) {
835 BasicBlock *OldBlock = BBMapping.first;
836 BasicBlock *NewBlock = BBMapping.second;
837 for (Instruction &OldI : *OldBlock) {
838 auto *OldPN = dyn_cast<PHINode>(&OldI);
841 UpdatePHIOnClonedBlock(OldPN, /*IsForOldBlock=*/true);
843 for (Instruction &NewI : *NewBlock) {
844 auto *NewPN = dyn_cast<PHINode>(&NewI);
847 UpdatePHIOnClonedBlock(NewPN, /*IsForOldBlock=*/false);
851 // Check to see if SuccBB has PHI nodes. If so, we need to add entries to
852 // the PHI nodes for NewBB now.
853 for (auto &BBMapping : Orig2Clone) {
854 BasicBlock *OldBlock = BBMapping.first;
855 BasicBlock *NewBlock = BBMapping.second;
856 for (BasicBlock *SuccBB : successors(NewBlock)) {
857 for (Instruction &SuccI : *SuccBB) {
858 auto *SuccPN = dyn_cast<PHINode>(&SuccI);
862 // Ok, we have a PHI node. Figure out what the incoming value was for
864 int OldBlockIdx = SuccPN->getBasicBlockIndex(OldBlock);
865 if (OldBlockIdx == -1)
867 Value *IV = SuccPN->getIncomingValue(OldBlockIdx);
869 // Remap the value if necessary.
870 if (auto *Inst = dyn_cast<Instruction>(IV)) {
871 ValueToValueMapTy::iterator I = VMap.find(Inst);
876 SuccPN->addIncoming(IV, NewBlock);
881 for (ValueToValueMapTy::value_type VT : VMap) {
882 // If there were values defined in BB that are used outside the funclet,
883 // then we now have to update all uses of the value to use either the
884 // original value, the cloned value, or some PHI derived value. This can
885 // require arbitrary PHI insertion, of which we are prepared to do, clean
887 SmallVector<Use *, 16> UsesToRename;
889 auto *OldI = dyn_cast<Instruction>(const_cast<Value *>(VT.first));
892 auto *NewI = cast<Instruction>(VT.second);
893 // Scan all uses of this instruction to see if it is used outside of its
894 // funclet, and if so, record them in UsesToRename.
895 for (Use &U : OldI->uses()) {
896 Instruction *UserI = cast<Instruction>(U.getUser());
897 BasicBlock *UserBB = UserI->getParent();
898 ColorVector &ColorsForUserBB = BlockColors[UserBB];
899 assert(!ColorsForUserBB.empty());
900 if (ColorsForUserBB.size() > 1 ||
901 *ColorsForUserBB.begin() != FuncletPadBB)
902 UsesToRename.push_back(&U);
905 // If there are no uses outside the block, we're done with this
907 if (UsesToRename.empty())
910 // We found a use of OldI outside of the funclet. Rename all uses of OldI
911 // that are outside its funclet to be uses of the appropriate PHI node
913 SSAUpdater SSAUpdate;
914 SSAUpdate.Initialize(OldI->getType(), OldI->getName());
915 SSAUpdate.AddAvailableValue(OldI->getParent(), OldI);
916 SSAUpdate.AddAvailableValue(NewI->getParent(), NewI);
918 while (!UsesToRename.empty())
919 SSAUpdate.RewriteUseAfterInsertions(*UsesToRename.pop_back_val());
924 void WinEHPrepare::removeImplausibleInstructions(Function &F) {
925 // Remove implausible terminators and replace them with UnreachableInst.
926 for (auto &Funclet : FuncletBlocks) {
927 BasicBlock *FuncletPadBB = Funclet.first;
928 std::vector<BasicBlock *> &BlocksInFunclet = Funclet.second;
929 Instruction *FirstNonPHI = FuncletPadBB->getFirstNonPHI();
930 auto *FuncletPad = dyn_cast<FuncletPadInst>(FirstNonPHI);
931 auto *CatchPad = dyn_cast_or_null<CatchPadInst>(FuncletPad);
932 auto *CleanupPad = dyn_cast_or_null<CleanupPadInst>(FuncletPad);
934 for (BasicBlock *BB : BlocksInFunclet) {
935 for (Instruction &I : *BB) {
940 Value *FuncletBundleOperand = nullptr;
941 if (auto BU = CS.getOperandBundle(LLVMContext::OB_funclet))
942 FuncletBundleOperand = BU->Inputs.front();
944 if (FuncletBundleOperand == FuncletPad)
947 // Skip call sites which are nounwind intrinsics.
949 dyn_cast<Function>(CS.getCalledValue()->stripPointerCasts());
950 if (CalledFn && CalledFn->isIntrinsic() && CS.doesNotThrow())
953 // This call site was not part of this funclet, remove it.
955 // Remove the unwind edge if it was an invoke.
956 removeUnwindEdge(BB);
957 // Get a pointer to the new call.
958 BasicBlock::iterator CallI =
959 std::prev(BB->getTerminator()->getIterator());
960 auto *CI = cast<CallInst>(&*CallI);
961 changeToUnreachable(CI, /*UseLLVMTrap=*/false);
963 changeToUnreachable(&I, /*UseLLVMTrap=*/false);
966 // There are no more instructions in the block (except for unreachable),
971 TerminatorInst *TI = BB->getTerminator();
972 // CatchPadInst and CleanupPadInst can't transfer control to a ReturnInst.
973 bool IsUnreachableRet = isa<ReturnInst>(TI) && FuncletPad;
974 // The token consumed by a CatchReturnInst must match the funclet token.
975 bool IsUnreachableCatchret = false;
976 if (auto *CRI = dyn_cast<CatchReturnInst>(TI))
977 IsUnreachableCatchret = CRI->getCatchPad() != CatchPad;
978 // The token consumed by a CleanupReturnInst must match the funclet token.
979 bool IsUnreachableCleanupret = false;
980 if (auto *CRI = dyn_cast<CleanupReturnInst>(TI))
981 IsUnreachableCleanupret = CRI->getCleanupPad() != CleanupPad;
982 if (IsUnreachableRet || IsUnreachableCatchret ||
983 IsUnreachableCleanupret) {
984 changeToUnreachable(TI, /*UseLLVMTrap=*/false);
985 } else if (isa<InvokeInst>(TI)) {
986 if (Personality == EHPersonality::MSVC_CXX && CleanupPad) {
987 // Invokes within a cleanuppad for the MSVC++ personality never
988 // transfer control to their unwind edge: the personality will
989 // terminate the program.
990 removeUnwindEdge(BB);
997 void WinEHPrepare::cleanupPreparedFunclets(Function &F) {
998 // Clean-up some of the mess we made by removing useles PHI nodes, trivial
1000 for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) {
1001 BasicBlock *BB = &*FI++;
1002 SimplifyInstructionsInBlock(BB);
1003 ConstantFoldTerminator(BB, /*DeleteDeadConditions=*/true);
1004 MergeBlockIntoPredecessor(BB);
1007 // We might have some unreachable blocks after cleaning up some impossible
1009 removeUnreachableBlocks(F);
1012 void WinEHPrepare::verifyPreparedFunclets(Function &F) {
1013 for (BasicBlock &BB : F) {
1014 size_t NumColors = BlockColors[&BB].size();
1015 assert(NumColors == 1 && "Expected monochromatic BB!");
1017 report_fatal_error("Uncolored BB!");
1019 report_fatal_error("Multicolor BB!");
1020 assert((DisableDemotion || !(BB.isEHPad() && isa<PHINode>(BB.begin()))) &&
1021 "EH Pad still has a PHI!");
1025 bool WinEHPrepare::prepareExplicitEH(Function &F) {
1026 // Remove unreachable blocks. It is not valuable to assign them a color and
1027 // their existence can trick us into thinking values are alive when they are
1029 removeUnreachableBlocks(F);
1031 // Determine which blocks are reachable from which funclet entries.
1034 cloneCommonBlocks(F);
1036 if (!DisableDemotion)
1037 demotePHIsOnFunclets(F);
1039 if (!DisableCleanups) {
1040 DEBUG(verifyFunction(F));
1041 removeImplausibleInstructions(F);
1043 DEBUG(verifyFunction(F));
1044 cleanupPreparedFunclets(F);
1047 DEBUG(verifyPreparedFunclets(F));
1048 // Recolor the CFG to verify that all is well.
1049 DEBUG(colorFunclets(F));
1050 DEBUG(verifyPreparedFunclets(F));
1052 BlockColors.clear();
1053 FuncletBlocks.clear();
1058 // TODO: Share loads when one use dominates another, or when a catchpad exit
1059 // dominates uses (needs dominators).
1060 AllocaInst *WinEHPrepare::insertPHILoads(PHINode *PN, Function &F) {
1061 BasicBlock *PHIBlock = PN->getParent();
1062 AllocaInst *SpillSlot = nullptr;
1063 Instruction *EHPad = PHIBlock->getFirstNonPHI();
1065 if (!isa<TerminatorInst>(EHPad)) {
1066 // If the EHPad isn't a terminator, then we can insert a load in this block
1067 // that will dominate all uses.
1068 SpillSlot = new AllocaInst(PN->getType(), nullptr,
1069 Twine(PN->getName(), ".wineh.spillslot"),
1070 &F.getEntryBlock().front());
1071 Value *V = new LoadInst(SpillSlot, Twine(PN->getName(), ".wineh.reload"),
1072 &*PHIBlock->getFirstInsertionPt());
1073 PN->replaceAllUsesWith(V);
1077 // Otherwise, we have a PHI on a terminator EHPad, and we give up and insert
1078 // loads of the slot before every use.
1079 DenseMap<BasicBlock *, Value *> Loads;
1080 for (Value::use_iterator UI = PN->use_begin(), UE = PN->use_end();
1083 auto *UsingInst = cast<Instruction>(U.getUser());
1084 if (isa<PHINode>(UsingInst) && UsingInst->getParent()->isEHPad()) {
1085 // Use is on an EH pad phi. Leave it alone; we'll insert loads and
1086 // stores for it separately.
1089 replaceUseWithLoad(PN, U, SpillSlot, Loads, F);
1094 // TODO: improve store placement. Inserting at def is probably good, but need
1095 // to be careful not to introduce interfering stores (needs liveness analysis).
1096 // TODO: identify related phi nodes that can share spill slots, and share them
1097 // (also needs liveness).
1098 void WinEHPrepare::insertPHIStores(PHINode *OriginalPHI,
1099 AllocaInst *SpillSlot) {
1100 // Use a worklist of (Block, Value) pairs -- the given Value needs to be
1101 // stored to the spill slot by the end of the given Block.
1102 SmallVector<std::pair<BasicBlock *, Value *>, 4> Worklist;
1104 Worklist.push_back({OriginalPHI->getParent(), OriginalPHI});
1106 while (!Worklist.empty()) {
1107 BasicBlock *EHBlock;
1109 std::tie(EHBlock, InVal) = Worklist.pop_back_val();
1111 PHINode *PN = dyn_cast<PHINode>(InVal);
1112 if (PN && PN->getParent() == EHBlock) {
1113 // The value is defined by another PHI we need to remove, with no room to
1114 // insert a store after the PHI, so each predecessor needs to store its
1116 for (unsigned i = 0, e = PN->getNumIncomingValues(); i < e; ++i) {
1117 Value *PredVal = PN->getIncomingValue(i);
1119 // Undef can safely be skipped.
1120 if (isa<UndefValue>(PredVal))
1123 insertPHIStore(PN->getIncomingBlock(i), PredVal, SpillSlot, Worklist);
1126 // We need to store InVal, which dominates EHBlock, but can't put a store
1127 // in EHBlock, so need to put stores in each predecessor.
1128 for (BasicBlock *PredBlock : predecessors(EHBlock)) {
1129 insertPHIStore(PredBlock, InVal, SpillSlot, Worklist);
1135 void WinEHPrepare::insertPHIStore(
1136 BasicBlock *PredBlock, Value *PredVal, AllocaInst *SpillSlot,
1137 SmallVectorImpl<std::pair<BasicBlock *, Value *>> &Worklist) {
1139 if (PredBlock->isEHPad() &&
1140 isa<TerminatorInst>(PredBlock->getFirstNonPHI())) {
1141 // Pred is unsplittable, so we need to queue it on the worklist.
1142 Worklist.push_back({PredBlock, PredVal});
1146 // Otherwise, insert the store at the end of the basic block.
1147 new StoreInst(PredVal, SpillSlot, PredBlock->getTerminator());
1150 void WinEHPrepare::replaceUseWithLoad(Value *V, Use &U, AllocaInst *&SpillSlot,
1151 DenseMap<BasicBlock *, Value *> &Loads,
1153 // Lazilly create the spill slot.
1155 SpillSlot = new AllocaInst(V->getType(), nullptr,
1156 Twine(V->getName(), ".wineh.spillslot"),
1157 &F.getEntryBlock().front());
1159 auto *UsingInst = cast<Instruction>(U.getUser());
1160 if (auto *UsingPHI = dyn_cast<PHINode>(UsingInst)) {
1161 // If this is a PHI node, we can't insert a load of the value before
1162 // the use. Instead insert the load in the predecessor block
1163 // corresponding to the incoming value.
1165 // Note that if there are multiple edges from a basic block to this
1166 // PHI node that we cannot have multiple loads. The problem is that
1167 // the resulting PHI node will have multiple values (from each load)
1168 // coming in from the same block, which is illegal SSA form.
1169 // For this reason, we keep track of and reuse loads we insert.
1170 BasicBlock *IncomingBlock = UsingPHI->getIncomingBlock(U);
1171 if (auto *CatchRet =
1172 dyn_cast<CatchReturnInst>(IncomingBlock->getTerminator())) {
1173 // Putting a load above a catchret and use on the phi would still leave
1174 // a cross-funclet def/use. We need to split the edge, change the
1175 // catchret to target the new block, and put the load there.
1176 BasicBlock *PHIBlock = UsingInst->getParent();
1177 BasicBlock *NewBlock = SplitEdge(IncomingBlock, PHIBlock);
1178 // SplitEdge gives us:
1181 // br label %NewBlock
1183 // catchret label %PHIBlock
1187 // catchret label %NewBlock
1189 // br label %PHIBlock
1190 // So move the terminators to each others' blocks and swap their
1192 BranchInst *Goto = cast<BranchInst>(IncomingBlock->getTerminator());
1193 Goto->removeFromParent();
1194 CatchRet->removeFromParent();
1195 IncomingBlock->getInstList().push_back(CatchRet);
1196 NewBlock->getInstList().push_back(Goto);
1197 Goto->setSuccessor(0, PHIBlock);
1198 CatchRet->setSuccessor(NewBlock);
1199 // Update the color mapping for the newly split edge.
1200 ColorVector &ColorsForPHIBlock = BlockColors[PHIBlock];
1201 BlockColors[NewBlock] = ColorsForPHIBlock;
1202 for (BasicBlock *FuncletPad : ColorsForPHIBlock)
1203 FuncletBlocks[FuncletPad].push_back(NewBlock);
1204 // Treat the new block as incoming for load insertion.
1205 IncomingBlock = NewBlock;
1207 Value *&Load = Loads[IncomingBlock];
1208 // Insert the load into the predecessor block
1210 Load = new LoadInst(SpillSlot, Twine(V->getName(), ".wineh.reload"),
1211 /*Volatile=*/false, IncomingBlock->getTerminator());
1215 // Reload right before the old use.
1216 auto *Load = new LoadInst(SpillSlot, Twine(V->getName(), ".wineh.reload"),
1217 /*Volatile=*/false, UsingInst);
1222 void WinEHFuncInfo::addIPToStateRange(const InvokeInst *II,
1223 MCSymbol *InvokeBegin,
1224 MCSymbol *InvokeEnd) {
1225 assert(InvokeStateMap.count(II) &&
1226 "should get invoke with precomputed state");
1227 LabelToStateMap[InvokeBegin] = std::make_pair(InvokeStateMap[II], InvokeEnd);
1230 WinEHFuncInfo::WinEHFuncInfo() {}