1//===-- WinEHPrepare - Prepare exception handling for code generation ---===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This pass lowers LLVM IR exception handling into something closer to what the
10// backend wants for functions using a personality function from a runtime
11// provided by MSVC. Functions with other personality functions are left alone
12// and may be prepared by other passes. In particular, all supported MSVC
13// personality functions require cleanup code to be outlined, and the C++
14// personality requires catch handler code to be outlined.
15//
16//===----------------------------------------------------------------------===//
17
18#include "llvm/CodeGen/WinEHPrepare.h"
19#include "llvm/ADT/DenseMap.h"
20#include "llvm/ADT/MapVector.h"
21#include "llvm/ADT/STLExtras.h"
22#include "llvm/CodeGen/MachineBasicBlock.h"
23#include "llvm/CodeGen/Passes.h"
24#include "llvm/CodeGen/WinEHFuncInfo.h"
25#include "llvm/IR/Constants.h"
26#include "llvm/IR/EHPersonalities.h"
27#include "llvm/IR/Instructions.h"
28#include "llvm/IR/Module.h"
29#include "llvm/IR/Verifier.h"
30#include "llvm/InitializePasses.h"
31#include "llvm/Pass.h"
32#include "llvm/Support/CommandLine.h"
33#include "llvm/Support/Debug.h"
34#include "llvm/Support/raw_ostream.h"
35#include "llvm/TargetParser/Triple.h"
36#include "llvm/Transforms/Utils/BasicBlockUtils.h"
37#include "llvm/Transforms/Utils/Cloning.h"
38#include "llvm/Transforms/Utils/Local.h"
39#include "llvm/Transforms/Utils/SSAUpdater.h"
40
41using namespace llvm;
42
43#define DEBUG_TYPE "win-eh-prepare"
44
45static cl::opt<bool> DisableDemotion(
46 "disable-demotion", cl::Hidden,
47 cl::desc(
48 "Clone multicolor basic blocks but do not demote cross scopes"),
49 cl::init(Val: false));
50
51static cl::opt<bool> DisableCleanups(
52 "disable-cleanups", cl::Hidden,
53 cl::desc("Do not remove implausible terminators or other similar cleanups"),
54 cl::init(Val: false));
55
56// TODO: Remove this option when we fully migrate to new pass manager
57static cl::opt<bool> DemoteCatchSwitchPHIOnlyOpt(
58 "demote-catchswitch-only", cl::Hidden,
59 cl::desc("Demote catchswitch BBs only (for wasm EH)"), cl::init(Val: false));
60
61namespace {
62
63class WinEHPrepareImpl {
64public:
65 WinEHPrepareImpl(bool DemoteCatchSwitchPHIOnly)
66 : DemoteCatchSwitchPHIOnly(DemoteCatchSwitchPHIOnly) {}
67
68 bool runOnFunction(Function &Fn);
69
70private:
71 void insertPHIStores(PHINode *OriginalPHI, AllocaInst *SpillSlot);
72 void
73 insertPHIStore(BasicBlock *PredBlock, Value *PredVal, AllocaInst *SpillSlot,
74 SmallVectorImpl<std::pair<BasicBlock *, Value *>> &Worklist);
75 AllocaInst *insertPHILoads(PHINode *PN, Function &F);
76 void replaceUseWithLoad(Value *V, Use &U, AllocaInst *&SpillSlot,
77 DenseMap<BasicBlock *, Value *> &Loads, Function &F);
78 bool prepareExplicitEH(Function &F);
79 void colorFunclets(Function &F);
80
81 void demotePHIsOnFunclets(Function &F, bool DemoteCatchSwitchPHIOnly);
82 void cloneCommonBlocks(Function &F);
83 void removeImplausibleInstructions(Function &F);
84 void cleanupPreparedFunclets(Function &F);
85 void verifyPreparedFunclets(Function &F);
86
87 bool DemoteCatchSwitchPHIOnly;
88
89 // All fields are reset by runOnFunction.
90 EHPersonality Personality = EHPersonality::Unknown;
91
92 const DataLayout *DL = nullptr;
93 DenseMap<BasicBlock *, ColorVector> BlockColors;
94 MapVector<BasicBlock *, std::vector<BasicBlock *>> FuncletBlocks;
95};
96
97class WinEHPrepare : public FunctionPass {
98 bool DemoteCatchSwitchPHIOnly;
99
100public:
101 static char ID; // Pass identification, replacement for typeid.
102
103 WinEHPrepare(bool DemoteCatchSwitchPHIOnly = false)
104 : FunctionPass(ID), DemoteCatchSwitchPHIOnly(DemoteCatchSwitchPHIOnly) {}
105
106 StringRef getPassName() const override {
107 return "Windows exception handling preparation";
108 }
109
110 bool runOnFunction(Function &Fn) override {
111 return WinEHPrepareImpl(DemoteCatchSwitchPHIOnly).runOnFunction(Fn);
112 }
113};
114
115} // end anonymous namespace
116
117PreservedAnalyses WinEHPreparePass::run(Function &F,
118 FunctionAnalysisManager &) {
119 bool Changed = WinEHPrepareImpl(DemoteCatchSwitchPHIOnly).runOnFunction(Fn&: F);
120 return Changed ? PreservedAnalyses::none() : PreservedAnalyses::all();
121}
122
123char WinEHPrepare::ID = 0;
124INITIALIZE_PASS(WinEHPrepare, DEBUG_TYPE, "Prepare Windows exceptions", false,
125 false)
126
127FunctionPass *llvm::createWinEHPass(bool DemoteCatchSwitchPHIOnly) {
128 return new WinEHPrepare(DemoteCatchSwitchPHIOnly);
129}
130
131bool WinEHPrepareImpl::runOnFunction(Function &Fn) {
132 if (!Fn.hasPersonalityFn())
133 return false;
134
135 // Classify the personality to see what kind of preparation we need.
136 Personality = classifyEHPersonality(Pers: Fn.getPersonalityFn());
137
138 // Do nothing if this is not a scope-based personality.
139 if (!isScopedEHPersonality(Pers: Personality))
140 return false;
141
142 DL = &Fn.getDataLayout();
143 return prepareExplicitEH(F&: Fn);
144}
145
146static int addUnwindMapEntry(WinEHFuncInfo &FuncInfo, int ToState,
147 const BasicBlock *BB) {
148 CxxUnwindMapEntry UME;
149 UME.ToState = ToState;
150 UME.Cleanup = BB;
151 FuncInfo.CxxUnwindMap.push_back(Elt: UME);
152 return FuncInfo.getLastStateNumber();
153}
154
155static void addTryBlockMapEntry(WinEHFuncInfo &FuncInfo, int TryLow,
156 int TryHigh, int CatchHigh,
157 ArrayRef<const CatchPadInst *> Handlers) {
158 WinEHTryBlockMapEntry TBME;
159 TBME.TryLow = TryLow;
160 TBME.TryHigh = TryHigh;
161 TBME.CatchHigh = CatchHigh;
162 assert(TBME.TryLow <= TBME.TryHigh);
163 for (const CatchPadInst *CPI : Handlers) {
164 WinEHHandlerType HT;
165 Constant *TypeInfo = cast<Constant>(Val: CPI->getArgOperand(i: 0));
166 if (TypeInfo->isNullValue())
167 HT.TypeDescriptor = nullptr;
168 else
169 HT.TypeDescriptor = cast<GlobalVariable>(Val: TypeInfo->stripPointerCasts());
170 HT.Adjectives = cast<ConstantInt>(Val: CPI->getArgOperand(i: 1))->getZExtValue();
171 HT.Handler = CPI->getParent();
172 if (auto *AI =
173 dyn_cast<AllocaInst>(Val: CPI->getArgOperand(i: 2)->stripPointerCasts()))
174 HT.CatchObj.Alloca = AI;
175 else
176 HT.CatchObj.Alloca = nullptr;
177 TBME.HandlerArray.push_back(Elt: HT);
178 }
179 FuncInfo.TryBlockMap.push_back(Elt: TBME);
180}
181
182static BasicBlock *getCleanupRetUnwindDest(const CleanupPadInst *CleanupPad) {
183 for (const User *U : CleanupPad->users())
184 if (const auto *CRI = dyn_cast<CleanupReturnInst>(Val: U))
185 return CRI->getUnwindDest();
186 return nullptr;
187}
188
189static void calculateStateNumbersForInvokes(const Function *Fn,
190 WinEHFuncInfo &FuncInfo) {
191 auto *F = const_cast<Function *>(Fn);
192 DenseMap<BasicBlock *, ColorVector> BlockColors = colorEHFunclets(F&: *F);
193 for (BasicBlock &BB : *F) {
194 auto *II = dyn_cast<InvokeInst>(Val: BB.getTerminator());
195 if (!II)
196 continue;
197
198 auto &BBColors = BlockColors[&BB];
199 assert(BBColors.size() == 1 && "multi-color BB not removed by preparation");
200 BasicBlock *FuncletEntryBB = BBColors.front();
201
202 BasicBlock *FuncletUnwindDest;
203 auto *FuncletPad =
204 dyn_cast<FuncletPadInst>(Val: FuncletEntryBB->getFirstNonPHI());
205 assert(FuncletPad || FuncletEntryBB == &Fn->getEntryBlock());
206 if (!FuncletPad)
207 FuncletUnwindDest = nullptr;
208 else if (auto *CatchPad = dyn_cast<CatchPadInst>(Val: FuncletPad))
209 FuncletUnwindDest = CatchPad->getCatchSwitch()->getUnwindDest();
210 else if (auto *CleanupPad = dyn_cast<CleanupPadInst>(Val: FuncletPad))
211 FuncletUnwindDest = getCleanupRetUnwindDest(CleanupPad);
212 else
213 llvm_unreachable("unexpected funclet pad!");
214
215 BasicBlock *InvokeUnwindDest = II->getUnwindDest();
216 int BaseState = -1;
217 if (FuncletUnwindDest == InvokeUnwindDest) {
218 auto BaseStateI = FuncInfo.FuncletBaseStateMap.find(Val: FuncletPad);
219 if (BaseStateI != FuncInfo.FuncletBaseStateMap.end())
220 BaseState = BaseStateI->second;
221 }
222
223 if (BaseState != -1) {
224 FuncInfo.InvokeStateMap[II] = BaseState;
225 } else {
226 Instruction *PadInst = InvokeUnwindDest->getFirstNonPHI();
227 assert(FuncInfo.EHPadStateMap.count(PadInst) && "EH Pad has no state!");
228 FuncInfo.InvokeStateMap[II] = FuncInfo.EHPadStateMap[PadInst];
229 }
230 }
231}
232
233// See comments below for calculateSEHStateForAsynchEH().
234// State - incoming State of normal paths
235struct WorkItem {
236 const BasicBlock *Block;
237 int State;
238 WorkItem(const BasicBlock *BB, int St) {
239 Block = BB;
240 State = St;
241 }
242};
243void llvm::calculateCXXStateForAsynchEH(const BasicBlock *BB, int State,
244 WinEHFuncInfo &EHInfo) {
245 SmallVector<struct WorkItem *, 8> WorkList;
246 struct WorkItem *WI = new WorkItem(BB, State);
247 WorkList.push_back(Elt: WI);
248
249 while (!WorkList.empty()) {
250 WI = WorkList.pop_back_val();
251 const BasicBlock *BB = WI->Block;
252 int State = WI->State;
253 delete WI;
254 if (EHInfo.BlockToStateMap.count(Val: BB) && EHInfo.BlockToStateMap[BB] <= State)
255 continue; // skip blocks already visited by lower State
256
257 const llvm::Instruction *I = BB->getFirstNonPHI();
258 const llvm::Instruction *TI = BB->getTerminator();
259 if (I->isEHPad())
260 State = EHInfo.EHPadStateMap[I];
261 EHInfo.BlockToStateMap[BB] = State; // Record state, also flag visiting
262
263 if ((isa<CleanupReturnInst>(Val: TI) || isa<CatchReturnInst>(Val: TI)) && State > 0) {
264 // Retrive the new State
265 State = EHInfo.CxxUnwindMap[State].ToState; // Retrive next State
266 } else if (isa<InvokeInst>(Val: TI)) {
267 auto *Call = cast<CallBase>(Val: TI);
268 const Function *Fn = Call->getCalledFunction();
269 if (Fn && Fn->isIntrinsic() &&
270 (Fn->getIntrinsicID() == Intrinsic::seh_scope_begin ||
271 Fn->getIntrinsicID() == Intrinsic::seh_try_begin))
272 // Retrive the new State from seh_scope_begin
273 State = EHInfo.InvokeStateMap[cast<InvokeInst>(Val: TI)];
274 else if (Fn && Fn->isIntrinsic() &&
275 (Fn->getIntrinsicID() == Intrinsic::seh_scope_end ||
276 Fn->getIntrinsicID() == Intrinsic::seh_try_end)) {
277 // In case of conditional ctor, let's retrieve State from Invoke
278 State = EHInfo.InvokeStateMap[cast<InvokeInst>(Val: TI)];
279 // end of current state, retrive new state from UnwindMap
280 State = EHInfo.CxxUnwindMap[State].ToState;
281 }
282 }
283 // Continue push successors into worklist
284 for (auto *SuccBB : successors(BB)) {
285 WI = new WorkItem(SuccBB, State);
286 WorkList.push_back(Elt: WI);
287 }
288 }
289}
290
291// The central theory of this routine is based on the following:
292// A _try scope is always a SEME (Single Entry Multiple Exits) region
293// as jumping into a _try is not allowed
294// The single entry must start with a seh_try_begin() invoke with a
295// correct State number that is the initial state of the SEME.
296// Through control-flow, state number is propagated into all blocks.
297// Side exits marked by seh_try_end() will unwind to parent state via
298// existing SEHUnwindMap[].
299// Side exits can ONLY jump into parent scopes (lower state number).
300// Thus, when a block succeeds various states from its predecessors,
301// the lowest State trumphs others.
302// If some exits flow to unreachable, propagation on those paths terminate,
303// not affecting remaining blocks.
304void llvm::calculateSEHStateForAsynchEH(const BasicBlock *BB, int State,
305 WinEHFuncInfo &EHInfo) {
306 SmallVector<struct WorkItem *, 8> WorkList;
307 struct WorkItem *WI = new WorkItem(BB, State);
308 WorkList.push_back(Elt: WI);
309
310 while (!WorkList.empty()) {
311 WI = WorkList.pop_back_val();
312 const BasicBlock *BB = WI->Block;
313 int State = WI->State;
314 delete WI;
315 if (EHInfo.BlockToStateMap.count(Val: BB) && EHInfo.BlockToStateMap[BB] <= State)
316 continue; // skip blocks already visited by lower State
317
318 const llvm::Instruction *I = BB->getFirstNonPHI();
319 const llvm::Instruction *TI = BB->getTerminator();
320 if (I->isEHPad())
321 State = EHInfo.EHPadStateMap[I];
322 EHInfo.BlockToStateMap[BB] = State; // Record state
323
324 if (isa<CatchPadInst>(Val: I) && isa<CatchReturnInst>(Val: TI)) {
325 const Constant *FilterOrNull = cast<Constant>(
326 Val: cast<CatchPadInst>(Val: I)->getArgOperand(i: 0)->stripPointerCasts());
327 const Function *Filter = dyn_cast<Function>(Val: FilterOrNull);
328 if (!Filter || !Filter->getName().starts_with(Prefix: "__IsLocalUnwind"))
329 State = EHInfo.SEHUnwindMap[State].ToState; // Retrive next State
330 } else if ((isa<CleanupReturnInst>(Val: TI) || isa<CatchReturnInst>(Val: TI)) &&
331 State > 0) {
332 // Retrive the new State.
333 State = EHInfo.SEHUnwindMap[State].ToState; // Retrive next State
334 } else if (isa<InvokeInst>(Val: TI)) {
335 auto *Call = cast<CallBase>(Val: TI);
336 const Function *Fn = Call->getCalledFunction();
337 if (Fn && Fn->isIntrinsic() &&
338 Fn->getIntrinsicID() == Intrinsic::seh_try_begin)
339 // Retrive the new State from seh_try_begin
340 State = EHInfo.InvokeStateMap[cast<InvokeInst>(Val: TI)];
341 else if (Fn && Fn->isIntrinsic() &&
342 Fn->getIntrinsicID() == Intrinsic::seh_try_end)
343 // end of current state, retrive new state from UnwindMap
344 State = EHInfo.SEHUnwindMap[State].ToState;
345 }
346 // Continue push successors into worklist
347 for (auto *SuccBB : successors(BB)) {
348 WI = new WorkItem(SuccBB, State);
349 WorkList.push_back(Elt: WI);
350 }
351 }
352}
353
354// Given BB which ends in an unwind edge, return the EHPad that this BB belongs
355// to. If the unwind edge came from an invoke, return null.
356static const BasicBlock *getEHPadFromPredecessor(const BasicBlock *BB,
357 Value *ParentPad) {
358 const Instruction *TI = BB->getTerminator();
359 if (isa<InvokeInst>(Val: TI))
360 return nullptr;
361 if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(Val: TI)) {
362 if (CatchSwitch->getParentPad() != ParentPad)
363 return nullptr;
364 return BB;
365 }
366 assert(!TI->isEHPad() && "unexpected EHPad!");
367 auto *CleanupPad = cast<CleanupReturnInst>(Val: TI)->getCleanupPad();
368 if (CleanupPad->getParentPad() != ParentPad)
369 return nullptr;
370 return CleanupPad->getParent();
371}
372
373// Starting from a EHPad, Backward walk through control-flow graph
374// to produce two primary outputs:
375// FuncInfo.EHPadStateMap[] and FuncInfo.CxxUnwindMap[]
376static void calculateCXXStateNumbers(WinEHFuncInfo &FuncInfo,
377 const Instruction *FirstNonPHI,
378 int ParentState) {
379 const BasicBlock *BB = FirstNonPHI->getParent();
380 assert(BB->isEHPad() && "not a funclet!");
381
382 if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(Val: FirstNonPHI)) {
383 assert(FuncInfo.EHPadStateMap.count(CatchSwitch) == 0 &&
384 "shouldn't revist catch funclets!");
385
386 SmallVector<const CatchPadInst *, 2> Handlers;
387 for (const BasicBlock *CatchPadBB : CatchSwitch->handlers()) {
388 auto *CatchPad = cast<CatchPadInst>(Val: CatchPadBB->getFirstNonPHI());
389 Handlers.push_back(Elt: CatchPad);
390 }
391 int TryLow = addUnwindMapEntry(FuncInfo, ToState: ParentState, BB: nullptr);
392 FuncInfo.EHPadStateMap[CatchSwitch] = TryLow;
393 for (const BasicBlock *PredBlock : predecessors(BB))
394 if ((PredBlock = getEHPadFromPredecessor(BB: PredBlock,
395 ParentPad: CatchSwitch->getParentPad())))
396 calculateCXXStateNumbers(FuncInfo, FirstNonPHI: PredBlock->getFirstNonPHI(),
397 ParentState: TryLow);
398 int CatchLow = addUnwindMapEntry(FuncInfo, ToState: ParentState, BB: nullptr);
399
400 // catchpads are separate funclets in C++ EH due to the way rethrow works.
401 int TryHigh = CatchLow - 1;
402
403 // MSVC FrameHandler3/4 on x64&Arm64 expect Catch Handlers in $tryMap$
404 // stored in pre-order (outer first, inner next), not post-order
405 // Add to map here. Fix the CatchHigh after children are processed
406 const Module *Mod = BB->getParent()->getParent();
407 bool IsPreOrder = Triple(Mod->getTargetTriple()).isArch64Bit();
408 if (IsPreOrder)
409 addTryBlockMapEntry(FuncInfo, TryLow, TryHigh, CatchHigh: CatchLow, Handlers);
410 unsigned TBMEIdx = FuncInfo.TryBlockMap.size() - 1;
411
412 for (const auto *CatchPad : Handlers) {
413 FuncInfo.FuncletBaseStateMap[CatchPad] = CatchLow;
414 FuncInfo.EHPadStateMap[CatchPad] = CatchLow;
415 for (const User *U : CatchPad->users()) {
416 const auto *UserI = cast<Instruction>(Val: U);
417 if (auto *InnerCatchSwitch = dyn_cast<CatchSwitchInst>(Val: UserI)) {
418 BasicBlock *UnwindDest = InnerCatchSwitch->getUnwindDest();
419 if (!UnwindDest || UnwindDest == CatchSwitch->getUnwindDest())
420 calculateCXXStateNumbers(FuncInfo, FirstNonPHI: UserI, ParentState: CatchLow);
421 }
422 if (auto *InnerCleanupPad = dyn_cast<CleanupPadInst>(Val: UserI)) {
423 BasicBlock *UnwindDest = getCleanupRetUnwindDest(CleanupPad: InnerCleanupPad);
424 // If a nested cleanup pad reports a null unwind destination and the
425 // enclosing catch pad doesn't it must be post-dominated by an
426 // unreachable instruction.
427 if (!UnwindDest || UnwindDest == CatchSwitch->getUnwindDest())
428 calculateCXXStateNumbers(FuncInfo, FirstNonPHI: UserI, ParentState: CatchLow);
429 }
430 }
431 }
432 int CatchHigh = FuncInfo.getLastStateNumber();
433 // Now child Catches are processed, update CatchHigh
434 if (IsPreOrder)
435 FuncInfo.TryBlockMap[TBMEIdx].CatchHigh = CatchHigh;
436 else // PostOrder
437 addTryBlockMapEntry(FuncInfo, TryLow, TryHigh, CatchHigh, Handlers);
438
439 LLVM_DEBUG(dbgs() << "TryLow[" << BB->getName() << "]: " << TryLow << '\n');
440 LLVM_DEBUG(dbgs() << "TryHigh[" << BB->getName() << "]: " << TryHigh
441 << '\n');
442 LLVM_DEBUG(dbgs() << "CatchHigh[" << BB->getName() << "]: " << CatchHigh
443 << '\n');
444 } else {
445 auto *CleanupPad = cast<CleanupPadInst>(Val: FirstNonPHI);
446
447 // It's possible for a cleanup to be visited twice: it might have multiple
448 // cleanupret instructions.
449 if (FuncInfo.EHPadStateMap.count(Val: CleanupPad))
450 return;
451
452 int CleanupState = addUnwindMapEntry(FuncInfo, ToState: ParentState, BB);
453 FuncInfo.EHPadStateMap[CleanupPad] = CleanupState;
454 LLVM_DEBUG(dbgs() << "Assigning state #" << CleanupState << " to BB "
455 << BB->getName() << '\n');
456 for (const BasicBlock *PredBlock : predecessors(BB)) {
457 if ((PredBlock = getEHPadFromPredecessor(BB: PredBlock,
458 ParentPad: CleanupPad->getParentPad()))) {
459 calculateCXXStateNumbers(FuncInfo, FirstNonPHI: PredBlock->getFirstNonPHI(),
460 ParentState: CleanupState);
461 }
462 }
463 for (const User *U : CleanupPad->users()) {
464 const auto *UserI = cast<Instruction>(Val: U);
465 if (UserI->isEHPad())
466 report_fatal_error(reason: "Cleanup funclets for the MSVC++ personality cannot "
467 "contain exceptional actions");
468 }
469 }
470}
471
472static int addSEHExcept(WinEHFuncInfo &FuncInfo, int ParentState,
473 const Function *Filter, const BasicBlock *Handler) {
474 SEHUnwindMapEntry Entry;
475 Entry.ToState = ParentState;
476 Entry.IsFinally = false;
477 Entry.Filter = Filter;
478 Entry.Handler = Handler;
479 FuncInfo.SEHUnwindMap.push_back(Elt: Entry);
480 return FuncInfo.SEHUnwindMap.size() - 1;
481}
482
483static int addSEHFinally(WinEHFuncInfo &FuncInfo, int ParentState,
484 const BasicBlock *Handler) {
485 SEHUnwindMapEntry Entry;
486 Entry.ToState = ParentState;
487 Entry.IsFinally = true;
488 Entry.Filter = nullptr;
489 Entry.Handler = Handler;
490 FuncInfo.SEHUnwindMap.push_back(Elt: Entry);
491 return FuncInfo.SEHUnwindMap.size() - 1;
492}
493
494// Starting from a EHPad, Backward walk through control-flow graph
495// to produce two primary outputs:
496// FuncInfo.EHPadStateMap[] and FuncInfo.SEHUnwindMap[]
497static void calculateSEHStateNumbers(WinEHFuncInfo &FuncInfo,
498 const Instruction *FirstNonPHI,
499 int ParentState) {
500 const BasicBlock *BB = FirstNonPHI->getParent();
501 assert(BB->isEHPad() && "no a funclet!");
502
503 if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(Val: FirstNonPHI)) {
504 assert(FuncInfo.EHPadStateMap.count(CatchSwitch) == 0 &&
505 "shouldn't revist catch funclets!");
506
507 // Extract the filter function and the __except basic block and create a
508 // state for them.
509 assert(CatchSwitch->getNumHandlers() == 1 &&
510 "SEH doesn't have multiple handlers per __try");
511 const auto *CatchPad =
512 cast<CatchPadInst>(Val: (*CatchSwitch->handler_begin())->getFirstNonPHI());
513 const BasicBlock *CatchPadBB = CatchPad->getParent();
514 const Constant *FilterOrNull =
515 cast<Constant>(Val: CatchPad->getArgOperand(i: 0)->stripPointerCasts());
516 const Function *Filter = dyn_cast<Function>(Val: FilterOrNull);
517 assert((Filter || FilterOrNull->isNullValue()) &&
518 "unexpected filter value");
519 int TryState = addSEHExcept(FuncInfo, ParentState, Filter, Handler: CatchPadBB);
520
521 // Everything in the __try block uses TryState as its parent state.
522 FuncInfo.EHPadStateMap[CatchSwitch] = TryState;
523 FuncInfo.EHPadStateMap[CatchPad] = TryState;
524 LLVM_DEBUG(dbgs() << "Assigning state #" << TryState << " to BB "
525 << CatchPadBB->getName() << '\n');
526 for (const BasicBlock *PredBlock : predecessors(BB))
527 if ((PredBlock = getEHPadFromPredecessor(BB: PredBlock,
528 ParentPad: CatchSwitch->getParentPad())))
529 calculateSEHStateNumbers(FuncInfo, FirstNonPHI: PredBlock->getFirstNonPHI(),
530 ParentState: TryState);
531
532 // Everything in the __except block unwinds to ParentState, just like code
533 // outside the __try.
534 for (const User *U : CatchPad->users()) {
535 const auto *UserI = cast<Instruction>(Val: U);
536 if (auto *InnerCatchSwitch = dyn_cast<CatchSwitchInst>(Val: UserI)) {
537 BasicBlock *UnwindDest = InnerCatchSwitch->getUnwindDest();
538 if (!UnwindDest || UnwindDest == CatchSwitch->getUnwindDest())
539 calculateSEHStateNumbers(FuncInfo, FirstNonPHI: UserI, ParentState);
540 }
541 if (auto *InnerCleanupPad = dyn_cast<CleanupPadInst>(Val: UserI)) {
542 BasicBlock *UnwindDest = getCleanupRetUnwindDest(CleanupPad: InnerCleanupPad);
543 // If a nested cleanup pad reports a null unwind destination and the
544 // enclosing catch pad doesn't it must be post-dominated by an
545 // unreachable instruction.
546 if (!UnwindDest || UnwindDest == CatchSwitch->getUnwindDest())
547 calculateSEHStateNumbers(FuncInfo, FirstNonPHI: UserI, ParentState);
548 }
549 }
550 } else {
551 auto *CleanupPad = cast<CleanupPadInst>(Val: FirstNonPHI);
552
553 // It's possible for a cleanup to be visited twice: it might have multiple
554 // cleanupret instructions.
555 if (FuncInfo.EHPadStateMap.count(Val: CleanupPad))
556 return;
557
558 int CleanupState = addSEHFinally(FuncInfo, ParentState, Handler: BB);
559 FuncInfo.EHPadStateMap[CleanupPad] = CleanupState;
560 LLVM_DEBUG(dbgs() << "Assigning state #" << CleanupState << " to BB "
561 << BB->getName() << '\n');
562 for (const BasicBlock *PredBlock : predecessors(BB))
563 if ((PredBlock =
564 getEHPadFromPredecessor(BB: PredBlock, ParentPad: CleanupPad->getParentPad())))
565 calculateSEHStateNumbers(FuncInfo, FirstNonPHI: PredBlock->getFirstNonPHI(),
566 ParentState: CleanupState);
567 for (const User *U : CleanupPad->users()) {
568 const auto *UserI = cast<Instruction>(Val: U);
569 if (UserI->isEHPad())
570 report_fatal_error(reason: "Cleanup funclets for the SEH personality cannot "
571 "contain exceptional actions");
572 }
573 }
574}
575
576static bool isTopLevelPadForMSVC(const Instruction *EHPad) {
577 if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(Val: EHPad))
578 return isa<ConstantTokenNone>(Val: CatchSwitch->getParentPad()) &&
579 CatchSwitch->unwindsToCaller();
580 if (auto *CleanupPad = dyn_cast<CleanupPadInst>(Val: EHPad))
581 return isa<ConstantTokenNone>(Val: CleanupPad->getParentPad()) &&
582 getCleanupRetUnwindDest(CleanupPad) == nullptr;
583 if (isa<CatchPadInst>(Val: EHPad))
584 return false;
585 llvm_unreachable("unexpected EHPad!");
586}
587
588void llvm::calculateSEHStateNumbers(const Function *Fn,
589 WinEHFuncInfo &FuncInfo) {
590 // Don't compute state numbers twice.
591 if (!FuncInfo.SEHUnwindMap.empty())
592 return;
593
594 for (const BasicBlock &BB : *Fn) {
595 if (!BB.isEHPad())
596 continue;
597 const Instruction *FirstNonPHI = BB.getFirstNonPHI();
598 if (!isTopLevelPadForMSVC(EHPad: FirstNonPHI))
599 continue;
600 ::calculateSEHStateNumbers(FuncInfo, FirstNonPHI, ParentState: -1);
601 }
602
603 calculateStateNumbersForInvokes(Fn, FuncInfo);
604
605 bool IsEHa = Fn->getParent()->getModuleFlag(Key: "eh-asynch");
606 if (IsEHa) {
607 const BasicBlock *EntryBB = &(Fn->getEntryBlock());
608 calculateSEHStateForAsynchEH(BB: EntryBB, State: -1, EHInfo&: FuncInfo);
609 }
610}
611
612void llvm::calculateWinCXXEHStateNumbers(const Function *Fn,
613 WinEHFuncInfo &FuncInfo) {
614 // Return if it's already been done.
615 if (!FuncInfo.EHPadStateMap.empty())
616 return;
617
618 for (const BasicBlock &BB : *Fn) {
619 if (!BB.isEHPad())
620 continue;
621 const Instruction *FirstNonPHI = BB.getFirstNonPHI();
622 if (!isTopLevelPadForMSVC(EHPad: FirstNonPHI))
623 continue;
624 calculateCXXStateNumbers(FuncInfo, FirstNonPHI, ParentState: -1);
625 }
626
627 calculateStateNumbersForInvokes(Fn, FuncInfo);
628
629 bool IsEHa = Fn->getParent()->getModuleFlag(Key: "eh-asynch");
630 if (IsEHa) {
631 const BasicBlock *EntryBB = &(Fn->getEntryBlock());
632 calculateCXXStateForAsynchEH(BB: EntryBB, State: -1, EHInfo&: FuncInfo);
633 }
634}
635
636static int addClrEHHandler(WinEHFuncInfo &FuncInfo, int HandlerParentState,
637 int TryParentState, ClrHandlerType HandlerType,
638 uint32_t TypeToken, const BasicBlock *Handler) {
639 ClrEHUnwindMapEntry Entry;
640 Entry.HandlerParentState = HandlerParentState;
641 Entry.TryParentState = TryParentState;
642 Entry.Handler = Handler;
643 Entry.HandlerType = HandlerType;
644 Entry.TypeToken = TypeToken;
645 FuncInfo.ClrEHUnwindMap.push_back(Elt: Entry);
646 return FuncInfo.ClrEHUnwindMap.size() - 1;
647}
648
649void llvm::calculateClrEHStateNumbers(const Function *Fn,
650 WinEHFuncInfo &FuncInfo) {
651 // Return if it's already been done.
652 if (!FuncInfo.EHPadStateMap.empty())
653 return;
654
655 // This numbering assigns one state number to each catchpad and cleanuppad.
656 // It also computes two tree-like relations over states:
657 // 1) Each state has a "HandlerParentState", which is the state of the next
658 // outer handler enclosing this state's handler (same as nearest ancestor
659 // per the ParentPad linkage on EH pads, but skipping over catchswitches).
660 // 2) Each state has a "TryParentState", which:
661 // a) for a catchpad that's not the last handler on its catchswitch, is
662 // the state of the next catchpad on that catchswitch
663 // b) for all other pads, is the state of the pad whose try region is the
664 // next outer try region enclosing this state's try region. The "try
665 // regions are not present as such in the IR, but will be inferred
666 // based on the placement of invokes and pads which reach each other
667 // by exceptional exits
668 // Catchswitches do not get their own states, but each gets mapped to the
669 // state of its first catchpad.
670
671 // Step one: walk down from outermost to innermost funclets, assigning each
672 // catchpad and cleanuppad a state number. Add an entry to the
673 // ClrEHUnwindMap for each state, recording its HandlerParentState and
674 // handler attributes. Record the TryParentState as well for each catchpad
675 // that's not the last on its catchswitch, but initialize all other entries'
676 // TryParentStates to a sentinel -1 value that the next pass will update.
677
678 // Seed a worklist with pads that have no parent.
679 SmallVector<std::pair<const Instruction *, int>, 8> Worklist;
680 for (const BasicBlock &BB : *Fn) {
681 const Instruction *FirstNonPHI = BB.getFirstNonPHI();
682 const Value *ParentPad;
683 if (const auto *CPI = dyn_cast<CleanupPadInst>(Val: FirstNonPHI))
684 ParentPad = CPI->getParentPad();
685 else if (const auto *CSI = dyn_cast<CatchSwitchInst>(Val: FirstNonPHI))
686 ParentPad = CSI->getParentPad();
687 else
688 continue;
689 if (isa<ConstantTokenNone>(Val: ParentPad))
690 Worklist.emplace_back(Args&: FirstNonPHI, Args: -1);
691 }
692
693 // Use the worklist to visit all pads, from outer to inner. Record
694 // HandlerParentState for all pads. Record TryParentState only for catchpads
695 // that aren't the last on their catchswitch (setting all other entries'
696 // TryParentStates to an initial value of -1). This loop is also responsible
697 // for setting the EHPadStateMap entry for all catchpads, cleanuppads, and
698 // catchswitches.
699 while (!Worklist.empty()) {
700 const Instruction *Pad;
701 int HandlerParentState;
702 std::tie(args&: Pad, args&: HandlerParentState) = Worklist.pop_back_val();
703
704 if (const auto *Cleanup = dyn_cast<CleanupPadInst>(Val: Pad)) {
705 // Create the entry for this cleanup with the appropriate handler
706 // properties. Finally and fault handlers are distinguished by arity.
707 ClrHandlerType HandlerType =
708 (Cleanup->arg_size() ? ClrHandlerType::Fault
709 : ClrHandlerType::Finally);
710 int CleanupState = addClrEHHandler(FuncInfo, HandlerParentState, TryParentState: -1,
711 HandlerType, TypeToken: 0, Handler: Pad->getParent());
712 // Queue any child EH pads on the worklist.
713 for (const User *U : Cleanup->users())
714 if (const auto *I = dyn_cast<Instruction>(Val: U))
715 if (I->isEHPad())
716 Worklist.emplace_back(Args&: I, Args&: CleanupState);
717 // Remember this pad's state.
718 FuncInfo.EHPadStateMap[Cleanup] = CleanupState;
719 } else {
720 // Walk the handlers of this catchswitch in reverse order since all but
721 // the last need to set the following one as its TryParentState.
722 const auto *CatchSwitch = cast<CatchSwitchInst>(Val: Pad);
723 int CatchState = -1, FollowerState = -1;
724 SmallVector<const BasicBlock *, 4> CatchBlocks(CatchSwitch->handlers());
725 for (const BasicBlock *CatchBlock : llvm::reverse(C&: CatchBlocks)) {
726 // Create the entry for this catch with the appropriate handler
727 // properties.
728 const auto *Catch = cast<CatchPadInst>(Val: CatchBlock->getFirstNonPHI());
729 uint32_t TypeToken = static_cast<uint32_t>(
730 cast<ConstantInt>(Val: Catch->getArgOperand(i: 0))->getZExtValue());
731 CatchState =
732 addClrEHHandler(FuncInfo, HandlerParentState, TryParentState: FollowerState,
733 HandlerType: ClrHandlerType::Catch, TypeToken, Handler: CatchBlock);
734 // Queue any child EH pads on the worklist.
735 for (const User *U : Catch->users())
736 if (const auto *I = dyn_cast<Instruction>(Val: U))
737 if (I->isEHPad())
738 Worklist.emplace_back(Args&: I, Args&: CatchState);
739 // Remember this catch's state.
740 FuncInfo.EHPadStateMap[Catch] = CatchState;
741 FollowerState = CatchState;
742 }
743 // Associate the catchswitch with the state of its first catch.
744 assert(CatchSwitch->getNumHandlers());
745 FuncInfo.EHPadStateMap[CatchSwitch] = CatchState;
746 }
747 }
748
749 // Step two: record the TryParentState of each state. For cleanuppads that
750 // don't have cleanuprets, we may need to infer this from their child pads,
751 // so visit pads in descendant-most to ancestor-most order.
752 for (ClrEHUnwindMapEntry &Entry : llvm::reverse(C&: FuncInfo.ClrEHUnwindMap)) {
753 const Instruction *Pad =
754 cast<const BasicBlock *>(Val&: Entry.Handler)->getFirstNonPHI();
755 // For most pads, the TryParentState is the state associated with the
756 // unwind dest of exceptional exits from it.
757 const BasicBlock *UnwindDest;
758 if (const auto *Catch = dyn_cast<CatchPadInst>(Val: Pad)) {
759 // If a catch is not the last in its catchswitch, its TryParentState is
760 // the state associated with the next catch in the switch, even though
761 // that's not the unwind dest of exceptions escaping the catch. Those
762 // cases were already assigned a TryParentState in the first pass, so
763 // skip them.
764 if (Entry.TryParentState != -1)
765 continue;
766 // Otherwise, get the unwind dest from the catchswitch.
767 UnwindDest = Catch->getCatchSwitch()->getUnwindDest();
768 } else {
769 const auto *Cleanup = cast<CleanupPadInst>(Val: Pad);
770 UnwindDest = nullptr;
771 for (const User *U : Cleanup->users()) {
772 if (auto *CleanupRet = dyn_cast<CleanupReturnInst>(Val: U)) {
773 // Common and unambiguous case -- cleanupret indicates cleanup's
774 // unwind dest.
775 UnwindDest = CleanupRet->getUnwindDest();
776 break;
777 }
778
779 // Get an unwind dest for the user
780 const BasicBlock *UserUnwindDest = nullptr;
781 if (auto *Invoke = dyn_cast<InvokeInst>(Val: U)) {
782 UserUnwindDest = Invoke->getUnwindDest();
783 } else if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(Val: U)) {
784 UserUnwindDest = CatchSwitch->getUnwindDest();
785 } else if (auto *ChildCleanup = dyn_cast<CleanupPadInst>(Val: U)) {
786 int UserState = FuncInfo.EHPadStateMap[ChildCleanup];
787 int UserUnwindState =
788 FuncInfo.ClrEHUnwindMap[UserState].TryParentState;
789 if (UserUnwindState != -1)
790 UserUnwindDest = cast<const BasicBlock *>(
791 Val&: FuncInfo.ClrEHUnwindMap[UserUnwindState].Handler);
792 }
793
794 // Not having an unwind dest for this user might indicate that it
795 // doesn't unwind, so can't be taken as proof that the cleanup itself
796 // may unwind to caller (see e.g. SimplifyUnreachable and
797 // RemoveUnwindEdge).
798 if (!UserUnwindDest)
799 continue;
800
801 // Now we have an unwind dest for the user, but we need to see if it
802 // unwinds all the way out of the cleanup or if it stays within it.
803 const Instruction *UserUnwindPad = UserUnwindDest->getFirstNonPHI();
804 const Value *UserUnwindParent;
805 if (auto *CSI = dyn_cast<CatchSwitchInst>(Val: UserUnwindPad))
806 UserUnwindParent = CSI->getParentPad();
807 else
808 UserUnwindParent =
809 cast<CleanupPadInst>(Val: UserUnwindPad)->getParentPad();
810
811 // The unwind stays within the cleanup iff it targets a child of the
812 // cleanup.
813 if (UserUnwindParent == Cleanup)
814 continue;
815
816 // This unwind exits the cleanup, so its dest is the cleanup's dest.
817 UnwindDest = UserUnwindDest;
818 break;
819 }
820 }
821
822 // Record the state of the unwind dest as the TryParentState.
823 int UnwindDestState;
824
825 // If UnwindDest is null at this point, either the pad in question can
826 // be exited by unwind to caller, or it cannot be exited by unwind. In
827 // either case, reporting such cases as unwinding to caller is correct.
828 // This can lead to EH tables that "look strange" -- if this pad's is in
829 // a parent funclet which has other children that do unwind to an enclosing
830 // pad, the try region for this pad will be missing the "duplicate" EH
831 // clause entries that you'd expect to see covering the whole parent. That
832 // should be benign, since the unwind never actually happens. If it were
833 // an issue, we could add a subsequent pass that pushes unwind dests down
834 // from parents that have them to children that appear to unwind to caller.
835 if (!UnwindDest) {
836 UnwindDestState = -1;
837 } else {
838 UnwindDestState = FuncInfo.EHPadStateMap[UnwindDest->getFirstNonPHI()];
839 }
840
841 Entry.TryParentState = UnwindDestState;
842 }
843
844 // Step three: transfer information from pads to invokes.
845 calculateStateNumbersForInvokes(Fn, FuncInfo);
846}
847
848void WinEHPrepareImpl::colorFunclets(Function &F) {
849 BlockColors = colorEHFunclets(F);
850
851 // Invert the map from BB to colors to color to BBs.
852 for (BasicBlock &BB : F) {
853 ColorVector &Colors = BlockColors[&BB];
854 for (BasicBlock *Color : Colors)
855 FuncletBlocks[Color].push_back(x: &BB);
856 }
857}
858
859void WinEHPrepareImpl::demotePHIsOnFunclets(Function &F,
860 bool DemoteCatchSwitchPHIOnly) {
861 // Strip PHI nodes off of EH pads.
862 SmallVector<PHINode *, 16> PHINodes;
863 for (BasicBlock &BB : make_early_inc_range(Range&: F)) {
864 if (!BB.isEHPad())
865 continue;
866 if (DemoteCatchSwitchPHIOnly && !isa<CatchSwitchInst>(Val: BB.getFirstNonPHI()))
867 continue;
868
869 for (Instruction &I : make_early_inc_range(Range&: BB)) {
870 auto *PN = dyn_cast<PHINode>(Val: &I);
871 // Stop at the first non-PHI.
872 if (!PN)
873 break;
874
875 AllocaInst *SpillSlot = insertPHILoads(PN, F);
876 if (SpillSlot)
877 insertPHIStores(OriginalPHI: PN, SpillSlot);
878
879 PHINodes.push_back(Elt: PN);
880 }
881 }
882
883 for (auto *PN : PHINodes) {
884 // There may be lingering uses on other EH PHIs being removed
885 PN->replaceAllUsesWith(V: PoisonValue::get(T: PN->getType()));
886 PN->eraseFromParent();
887 }
888}
889
890void WinEHPrepareImpl::cloneCommonBlocks(Function &F) {
891 // We need to clone all blocks which belong to multiple funclets. Values are
892 // remapped throughout the funclet to propagate both the new instructions
893 // *and* the new basic blocks themselves.
894 for (auto &Funclets : FuncletBlocks) {
895 BasicBlock *FuncletPadBB = Funclets.first;
896 std::vector<BasicBlock *> &BlocksInFunclet = Funclets.second;
897 Value *FuncletToken;
898 if (FuncletPadBB == &F.getEntryBlock())
899 FuncletToken = ConstantTokenNone::get(Context&: F.getContext());
900 else
901 FuncletToken = FuncletPadBB->getFirstNonPHI();
902
903 std::vector<std::pair<BasicBlock *, BasicBlock *>> Orig2Clone;
904 ValueToValueMapTy VMap;
905 for (BasicBlock *BB : BlocksInFunclet) {
906 ColorVector &ColorsForBB = BlockColors[BB];
907 // We don't need to do anything if the block is monochromatic.
908 size_t NumColorsForBB = ColorsForBB.size();
909 if (NumColorsForBB == 1)
910 continue;
911
912 DEBUG_WITH_TYPE("win-eh-prepare-coloring",
913 dbgs() << " Cloning block \'" << BB->getName()
914 << "\' for funclet \'" << FuncletPadBB->getName()
915 << "\'.\n");
916
917 // Create a new basic block and copy instructions into it!
918 BasicBlock *CBB =
919 CloneBasicBlock(BB, VMap, NameSuffix: Twine(".for.", FuncletPadBB->getName()));
920 // Insert the clone immediately after the original to ensure determinism
921 // and to keep the same relative ordering of any funclet's blocks.
922 CBB->insertInto(Parent: &F, InsertBefore: BB->getNextNode());
923
924 // Add basic block mapping.
925 VMap[BB] = CBB;
926
927 // Record delta operations that we need to perform to our color mappings.
928 Orig2Clone.emplace_back(args&: BB, args&: CBB);
929 }
930
931 // If nothing was cloned, we're done cloning in this funclet.
932 if (Orig2Clone.empty())
933 continue;
934
935 // Update our color mappings to reflect that one block has lost a color and
936 // another has gained a color.
937 for (auto &BBMapping : Orig2Clone) {
938 BasicBlock *OldBlock = BBMapping.first;
939 BasicBlock *NewBlock = BBMapping.second;
940
941 BlocksInFunclet.push_back(x: NewBlock);
942 ColorVector &NewColors = BlockColors[NewBlock];
943 assert(NewColors.empty() && "A new block should only have one color!");
944 NewColors.push_back(NewVal: FuncletPadBB);
945
946 DEBUG_WITH_TYPE("win-eh-prepare-coloring",
947 dbgs() << " Assigned color \'" << FuncletPadBB->getName()
948 << "\' to block \'" << NewBlock->getName()
949 << "\'.\n");
950
951 llvm::erase(C&: BlocksInFunclet, V: OldBlock);
952 ColorVector &OldColors = BlockColors[OldBlock];
953 llvm::erase(C&: OldColors, V: FuncletPadBB);
954
955 DEBUG_WITH_TYPE("win-eh-prepare-coloring",
956 dbgs() << " Removed color \'" << FuncletPadBB->getName()
957 << "\' from block \'" << OldBlock->getName()
958 << "\'.\n");
959 }
960
961 // Loop over all of the instructions in this funclet, fixing up operand
962 // references as we go. This uses VMap to do all the hard work.
963 for (BasicBlock *BB : BlocksInFunclet)
964 // Loop over all instructions, fixing each one as we find it...
965 for (Instruction &I : *BB)
966 RemapInstruction(I: &I, VM&: VMap,
967 Flags: RF_IgnoreMissingLocals | RF_NoModuleLevelChanges);
968
969 // Catchrets targeting cloned blocks need to be updated separately from
970 // the loop above because they are not in the current funclet.
971 SmallVector<CatchReturnInst *, 2> FixupCatchrets;
972 for (auto &BBMapping : Orig2Clone) {
973 BasicBlock *OldBlock = BBMapping.first;
974 BasicBlock *NewBlock = BBMapping.second;
975
976 FixupCatchrets.clear();
977 for (BasicBlock *Pred : predecessors(BB: OldBlock))
978 if (auto *CatchRet = dyn_cast<CatchReturnInst>(Val: Pred->getTerminator()))
979 if (CatchRet->getCatchSwitchParentPad() == FuncletToken)
980 FixupCatchrets.push_back(Elt: CatchRet);
981
982 for (CatchReturnInst *CatchRet : FixupCatchrets)
983 CatchRet->setSuccessor(NewBlock);
984 }
985
986 auto UpdatePHIOnClonedBlock = [&](PHINode *PN, bool IsForOldBlock) {
987 unsigned NumPreds = PN->getNumIncomingValues();
988 for (unsigned PredIdx = 0, PredEnd = NumPreds; PredIdx != PredEnd;
989 ++PredIdx) {
990 BasicBlock *IncomingBlock = PN->getIncomingBlock(i: PredIdx);
991 bool EdgeTargetsFunclet;
992 if (auto *CRI =
993 dyn_cast<CatchReturnInst>(Val: IncomingBlock->getTerminator())) {
994 EdgeTargetsFunclet = (CRI->getCatchSwitchParentPad() == FuncletToken);
995 } else {
996 ColorVector &IncomingColors = BlockColors[IncomingBlock];
997 assert(!IncomingColors.empty() && "Block not colored!");
998 assert((IncomingColors.size() == 1 ||
999 !llvm::is_contained(IncomingColors, FuncletPadBB)) &&
1000 "Cloning should leave this funclet's blocks monochromatic");
1001 EdgeTargetsFunclet = (IncomingColors.front() == FuncletPadBB);
1002 }
1003 if (IsForOldBlock != EdgeTargetsFunclet)
1004 continue;
1005 PN->removeIncomingValue(BB: IncomingBlock, /*DeletePHIIfEmpty=*/false);
1006 // Revisit the next entry.
1007 --PredIdx;
1008 --PredEnd;
1009 }
1010 };
1011
1012 for (auto &BBMapping : Orig2Clone) {
1013 BasicBlock *OldBlock = BBMapping.first;
1014 BasicBlock *NewBlock = BBMapping.second;
1015 for (PHINode &OldPN : OldBlock->phis()) {
1016 UpdatePHIOnClonedBlock(&OldPN, /*IsForOldBlock=*/true);
1017 }
1018 for (PHINode &NewPN : NewBlock->phis()) {
1019 UpdatePHIOnClonedBlock(&NewPN, /*IsForOldBlock=*/false);
1020 }
1021 }
1022
1023 // Check to see if SuccBB has PHI nodes. If so, we need to add entries to
1024 // the PHI nodes for NewBB now.
1025 for (auto &BBMapping : Orig2Clone) {
1026 BasicBlock *OldBlock = BBMapping.first;
1027 BasicBlock *NewBlock = BBMapping.second;
1028 for (BasicBlock *SuccBB : successors(BB: NewBlock)) {
1029 for (PHINode &SuccPN : SuccBB->phis()) {
1030 // Ok, we have a PHI node. Figure out what the incoming value was for
1031 // the OldBlock.
1032 int OldBlockIdx = SuccPN.getBasicBlockIndex(BB: OldBlock);
1033 if (OldBlockIdx == -1)
1034 break;
1035 Value *IV = SuccPN.getIncomingValue(i: OldBlockIdx);
1036
1037 // Remap the value if necessary.
1038 if (auto *Inst = dyn_cast<Instruction>(Val: IV)) {
1039 ValueToValueMapTy::iterator I = VMap.find(Val: Inst);
1040 if (I != VMap.end())
1041 IV = I->second;
1042 }
1043
1044 SuccPN.addIncoming(V: IV, BB: NewBlock);
1045 }
1046 }
1047 }
1048
1049 for (ValueToValueMapTy::value_type VT : VMap) {
1050 // If there were values defined in BB that are used outside the funclet,
1051 // then we now have to update all uses of the value to use either the
1052 // original value, the cloned value, or some PHI derived value. This can
1053 // require arbitrary PHI insertion, of which we are prepared to do, clean
1054 // these up now.
1055 SmallVector<Use *, 16> UsesToRename;
1056
1057 auto *OldI = dyn_cast<Instruction>(Val: const_cast<Value *>(VT.first));
1058 if (!OldI)
1059 continue;
1060 auto *NewI = cast<Instruction>(Val&: VT.second);
1061 // Scan all uses of this instruction to see if it is used outside of its
1062 // funclet, and if so, record them in UsesToRename.
1063 for (Use &U : OldI->uses()) {
1064 Instruction *UserI = cast<Instruction>(Val: U.getUser());
1065 BasicBlock *UserBB = UserI->getParent();
1066 ColorVector &ColorsForUserBB = BlockColors[UserBB];
1067 assert(!ColorsForUserBB.empty());
1068 if (ColorsForUserBB.size() > 1 ||
1069 *ColorsForUserBB.begin() != FuncletPadBB)
1070 UsesToRename.push_back(Elt: &U);
1071 }
1072
1073 // If there are no uses outside the block, we're done with this
1074 // instruction.
1075 if (UsesToRename.empty())
1076 continue;
1077
1078 // We found a use of OldI outside of the funclet. Rename all uses of OldI
1079 // that are outside its funclet to be uses of the appropriate PHI node
1080 // etc.
1081 SSAUpdater SSAUpdate;
1082 SSAUpdate.Initialize(Ty: OldI->getType(), Name: OldI->getName());
1083 SSAUpdate.AddAvailableValue(BB: OldI->getParent(), V: OldI);
1084 SSAUpdate.AddAvailableValue(BB: NewI->getParent(), V: NewI);
1085
1086 while (!UsesToRename.empty())
1087 SSAUpdate.RewriteUseAfterInsertions(U&: *UsesToRename.pop_back_val());
1088 }
1089 }
1090}
1091
1092void WinEHPrepareImpl::removeImplausibleInstructions(Function &F) {
1093 // Remove implausible terminators and replace them with UnreachableInst.
1094 for (auto &Funclet : FuncletBlocks) {
1095 BasicBlock *FuncletPadBB = Funclet.first;
1096 std::vector<BasicBlock *> &BlocksInFunclet = Funclet.second;
1097 Instruction *FirstNonPHI = FuncletPadBB->getFirstNonPHI();
1098 auto *FuncletPad = dyn_cast<FuncletPadInst>(Val: FirstNonPHI);
1099 auto *CatchPad = dyn_cast_or_null<CatchPadInst>(Val: FuncletPad);
1100 auto *CleanupPad = dyn_cast_or_null<CleanupPadInst>(Val: FuncletPad);
1101
1102 for (BasicBlock *BB : BlocksInFunclet) {
1103 for (Instruction &I : *BB) {
1104 auto *CB = dyn_cast<CallBase>(Val: &I);
1105 if (!CB)
1106 continue;
1107
1108 Value *FuncletBundleOperand = nullptr;
1109 if (auto BU = CB->getOperandBundle(ID: LLVMContext::OB_funclet))
1110 FuncletBundleOperand = BU->Inputs.front();
1111
1112 if (FuncletBundleOperand == FuncletPad)
1113 continue;
1114
1115 // Skip call sites which are nounwind intrinsics or inline asm.
1116 auto *CalledFn =
1117 dyn_cast<Function>(Val: CB->getCalledOperand()->stripPointerCasts());
1118 if (CalledFn && ((CalledFn->isIntrinsic() && CB->doesNotThrow()) ||
1119 CB->isInlineAsm()))
1120 continue;
1121
1122 // This call site was not part of this funclet, remove it.
1123 if (isa<InvokeInst>(Val: CB)) {
1124 // Remove the unwind edge if it was an invoke.
1125 removeUnwindEdge(BB);
1126 // Get a pointer to the new call.
1127 BasicBlock::iterator CallI =
1128 std::prev(x: BB->getTerminator()->getIterator());
1129 auto *CI = cast<CallInst>(Val: &*CallI);
1130 changeToUnreachable(I: CI);
1131 } else {
1132 changeToUnreachable(I: &I);
1133 }
1134
1135 // There are no more instructions in the block (except for unreachable),
1136 // we are done.
1137 break;
1138 }
1139
1140 Instruction *TI = BB->getTerminator();
1141 // CatchPadInst and CleanupPadInst can't transfer control to a ReturnInst.
1142 bool IsUnreachableRet = isa<ReturnInst>(Val: TI) && FuncletPad;
1143 // The token consumed by a CatchReturnInst must match the funclet token.
1144 bool IsUnreachableCatchret = false;
1145 if (auto *CRI = dyn_cast<CatchReturnInst>(Val: TI))
1146 IsUnreachableCatchret = CRI->getCatchPad() != CatchPad;
1147 // The token consumed by a CleanupReturnInst must match the funclet token.
1148 bool IsUnreachableCleanupret = false;
1149 if (auto *CRI = dyn_cast<CleanupReturnInst>(Val: TI))
1150 IsUnreachableCleanupret = CRI->getCleanupPad() != CleanupPad;
1151 if (IsUnreachableRet || IsUnreachableCatchret ||
1152 IsUnreachableCleanupret) {
1153 changeToUnreachable(I: TI);
1154 } else if (isa<InvokeInst>(Val: TI)) {
1155 if (Personality == EHPersonality::MSVC_CXX && CleanupPad) {
1156 // Invokes within a cleanuppad for the MSVC++ personality never
1157 // transfer control to their unwind edge: the personality will
1158 // terminate the program.
1159 removeUnwindEdge(BB);
1160 }
1161 }
1162 }
1163 }
1164}
1165
1166void WinEHPrepareImpl::cleanupPreparedFunclets(Function &F) {
1167 // Clean-up some of the mess we made by removing useles PHI nodes, trivial
1168 // branches, etc.
1169 for (BasicBlock &BB : llvm::make_early_inc_range(Range&: F)) {
1170 SimplifyInstructionsInBlock(BB: &BB);
1171 ConstantFoldTerminator(BB: &BB, /*DeleteDeadConditions=*/true);
1172 MergeBlockIntoPredecessor(BB: &BB);
1173 }
1174
1175 // We might have some unreachable blocks after cleaning up some impossible
1176 // control flow.
1177 removeUnreachableBlocks(F);
1178}
1179
1180#ifndef NDEBUG
1181void WinEHPrepareImpl::verifyPreparedFunclets(Function &F) {
1182 for (BasicBlock &BB : F) {
1183 size_t NumColors = BlockColors[&BB].size();
1184 assert(NumColors == 1 && "Expected monochromatic BB!");
1185 if (NumColors == 0)
1186 report_fatal_error("Uncolored BB!");
1187 if (NumColors > 1)
1188 report_fatal_error("Multicolor BB!");
1189 assert((DisableDemotion || !(BB.isEHPad() && isa<PHINode>(BB.begin()))) &&
1190 "EH Pad still has a PHI!");
1191 }
1192}
1193#endif
1194
1195bool WinEHPrepareImpl::prepareExplicitEH(Function &F) {
1196 // Remove unreachable blocks. It is not valuable to assign them a color and
1197 // their existence can trick us into thinking values are alive when they are
1198 // not.
1199 removeUnreachableBlocks(F);
1200
1201 // Determine which blocks are reachable from which funclet entries.
1202 colorFunclets(F);
1203
1204 cloneCommonBlocks(F);
1205
1206 if (!DisableDemotion)
1207 demotePHIsOnFunclets(F, DemoteCatchSwitchPHIOnly: DemoteCatchSwitchPHIOnly ||
1208 DemoteCatchSwitchPHIOnlyOpt);
1209
1210 if (!DisableCleanups) {
1211 assert(!verifyFunction(F, &dbgs()));
1212 removeImplausibleInstructions(F);
1213
1214 assert(!verifyFunction(F, &dbgs()));
1215 cleanupPreparedFunclets(F);
1216 }
1217
1218 LLVM_DEBUG(verifyPreparedFunclets(F));
1219 // Recolor the CFG to verify that all is well.
1220 LLVM_DEBUG(colorFunclets(F));
1221 LLVM_DEBUG(verifyPreparedFunclets(F));
1222
1223 return true;
1224}
1225
1226// TODO: Share loads when one use dominates another, or when a catchpad exit
1227// dominates uses (needs dominators).
1228AllocaInst *WinEHPrepareImpl::insertPHILoads(PHINode *PN, Function &F) {
1229 BasicBlock *PHIBlock = PN->getParent();
1230 AllocaInst *SpillSlot = nullptr;
1231 Instruction *EHPad = PHIBlock->getFirstNonPHI();
1232
1233 if (!EHPad->isTerminator()) {
1234 // If the EHPad isn't a terminator, then we can insert a load in this block
1235 // that will dominate all uses.
1236 SpillSlot = new AllocaInst(PN->getType(), DL->getAllocaAddrSpace(), nullptr,
1237 Twine(PN->getName(), ".wineh.spillslot"),
1238 F.getEntryBlock().begin());
1239 Value *V = new LoadInst(PN->getType(), SpillSlot,
1240 Twine(PN->getName(), ".wineh.reload"),
1241 PHIBlock->getFirstInsertionPt());
1242 PN->replaceAllUsesWith(V);
1243 return SpillSlot;
1244 }
1245
1246 // Otherwise, we have a PHI on a terminator EHPad, and we give up and insert
1247 // loads of the slot before every use.
1248 DenseMap<BasicBlock *, Value *> Loads;
1249 for (Use &U : llvm::make_early_inc_range(Range: PN->uses())) {
1250 auto *UsingInst = cast<Instruction>(Val: U.getUser());
1251 if (isa<PHINode>(Val: UsingInst) && UsingInst->getParent()->isEHPad()) {
1252 // Use is on an EH pad phi. Leave it alone; we'll insert loads and
1253 // stores for it separately.
1254 continue;
1255 }
1256 replaceUseWithLoad(V: PN, U, SpillSlot, Loads, F);
1257 }
1258 return SpillSlot;
1259}
1260
1261// TODO: improve store placement. Inserting at def is probably good, but need
1262// to be careful not to introduce interfering stores (needs liveness analysis).
1263// TODO: identify related phi nodes that can share spill slots, and share them
1264// (also needs liveness).
1265void WinEHPrepareImpl::insertPHIStores(PHINode *OriginalPHI,
1266 AllocaInst *SpillSlot) {
1267 // Use a worklist of (Block, Value) pairs -- the given Value needs to be
1268 // stored to the spill slot by the end of the given Block.
1269 SmallVector<std::pair<BasicBlock *, Value *>, 4> Worklist;
1270
1271 Worklist.push_back(Elt: {OriginalPHI->getParent(), OriginalPHI});
1272
1273 while (!Worklist.empty()) {
1274 BasicBlock *EHBlock;
1275 Value *InVal;
1276 std::tie(args&: EHBlock, args&: InVal) = Worklist.pop_back_val();
1277
1278 PHINode *PN = dyn_cast<PHINode>(Val: InVal);
1279 if (PN && PN->getParent() == EHBlock) {
1280 // The value is defined by another PHI we need to remove, with no room to
1281 // insert a store after the PHI, so each predecessor needs to store its
1282 // incoming value.
1283 for (unsigned i = 0, e = PN->getNumIncomingValues(); i < e; ++i) {
1284 Value *PredVal = PN->getIncomingValue(i);
1285
1286 // Undef can safely be skipped.
1287 if (isa<UndefValue>(Val: PredVal))
1288 continue;
1289
1290 insertPHIStore(PredBlock: PN->getIncomingBlock(i), PredVal, SpillSlot, Worklist);
1291 }
1292 } else {
1293 // We need to store InVal, which dominates EHBlock, but can't put a store
1294 // in EHBlock, so need to put stores in each predecessor.
1295 for (BasicBlock *PredBlock : predecessors(BB: EHBlock)) {
1296 insertPHIStore(PredBlock, PredVal: InVal, SpillSlot, Worklist);
1297 }
1298 }
1299 }
1300}
1301
1302void WinEHPrepareImpl::insertPHIStore(
1303 BasicBlock *PredBlock, Value *PredVal, AllocaInst *SpillSlot,
1304 SmallVectorImpl<std::pair<BasicBlock *, Value *>> &Worklist) {
1305
1306 if (PredBlock->isEHPad() && PredBlock->getFirstNonPHI()->isTerminator()) {
1307 // Pred is unsplittable, so we need to queue it on the worklist.
1308 Worklist.push_back(Elt: {PredBlock, PredVal});
1309 return;
1310 }
1311
1312 // Otherwise, insert the store at the end of the basic block.
1313 new StoreInst(PredVal, SpillSlot, PredBlock->getTerminator()->getIterator());
1314}
1315
1316void WinEHPrepareImpl::replaceUseWithLoad(
1317 Value *V, Use &U, AllocaInst *&SpillSlot,
1318 DenseMap<BasicBlock *, Value *> &Loads, Function &F) {
1319 // Lazilly create the spill slot.
1320 if (!SpillSlot)
1321 SpillSlot = new AllocaInst(V->getType(), DL->getAllocaAddrSpace(), nullptr,
1322 Twine(V->getName(), ".wineh.spillslot"),
1323 F.getEntryBlock().begin());
1324
1325 auto *UsingInst = cast<Instruction>(Val: U.getUser());
1326 if (auto *UsingPHI = dyn_cast<PHINode>(Val: UsingInst)) {
1327 // If this is a PHI node, we can't insert a load of the value before
1328 // the use. Instead insert the load in the predecessor block
1329 // corresponding to the incoming value.
1330 //
1331 // Note that if there are multiple edges from a basic block to this
1332 // PHI node that we cannot have multiple loads. The problem is that
1333 // the resulting PHI node will have multiple values (from each load)
1334 // coming in from the same block, which is illegal SSA form.
1335 // For this reason, we keep track of and reuse loads we insert.
1336 BasicBlock *IncomingBlock = UsingPHI->getIncomingBlock(U);
1337 if (auto *CatchRet =
1338 dyn_cast<CatchReturnInst>(Val: IncomingBlock->getTerminator())) {
1339 // Putting a load above a catchret and use on the phi would still leave
1340 // a cross-funclet def/use. We need to split the edge, change the
1341 // catchret to target the new block, and put the load there.
1342 BasicBlock *PHIBlock = UsingInst->getParent();
1343 BasicBlock *NewBlock = SplitEdge(From: IncomingBlock, To: PHIBlock);
1344 // SplitEdge gives us:
1345 // IncomingBlock:
1346 // ...
1347 // br label %NewBlock
1348 // NewBlock:
1349 // catchret label %PHIBlock
1350 // But we need:
1351 // IncomingBlock:
1352 // ...
1353 // catchret label %NewBlock
1354 // NewBlock:
1355 // br label %PHIBlock
1356 // So move the terminators to each others' blocks and swap their
1357 // successors.
1358 BranchInst *Goto = cast<BranchInst>(Val: IncomingBlock->getTerminator());
1359 Goto->removeFromParent();
1360 CatchRet->removeFromParent();
1361 CatchRet->insertInto(ParentBB: IncomingBlock, It: IncomingBlock->end());
1362 Goto->insertInto(ParentBB: NewBlock, It: NewBlock->end());
1363 Goto->setSuccessor(idx: 0, NewSucc: PHIBlock);
1364 CatchRet->setSuccessor(NewBlock);
1365 // Update the color mapping for the newly split edge.
1366 // Grab a reference to the ColorVector to be inserted before getting the
1367 // reference to the vector we are copying because inserting the new
1368 // element in BlockColors might cause the map to be reallocated.
1369 ColorVector &ColorsForNewBlock = BlockColors[NewBlock];
1370 ColorVector &ColorsForPHIBlock = BlockColors[PHIBlock];
1371 ColorsForNewBlock = ColorsForPHIBlock;
1372 for (BasicBlock *FuncletPad : ColorsForPHIBlock)
1373 FuncletBlocks[FuncletPad].push_back(x: NewBlock);
1374 // Treat the new block as incoming for load insertion.
1375 IncomingBlock = NewBlock;
1376 }
1377 Value *&Load = Loads[IncomingBlock];
1378 // Insert the load into the predecessor block
1379 if (!Load)
1380 Load = new LoadInst(
1381 V->getType(), SpillSlot, Twine(V->getName(), ".wineh.reload"),
1382 /*isVolatile=*/false, IncomingBlock->getTerminator()->getIterator());
1383
1384 U.set(Load);
1385 } else {
1386 // Reload right before the old use.
1387 auto *Load = new LoadInst(V->getType(), SpillSlot,
1388 Twine(V->getName(), ".wineh.reload"),
1389 /*isVolatile=*/false, UsingInst->getIterator());
1390 U.set(Load);
1391 }
1392}
1393
1394void WinEHFuncInfo::addIPToStateRange(const InvokeInst *II,
1395 MCSymbol *InvokeBegin,
1396 MCSymbol *InvokeEnd) {
1397 assert(InvokeStateMap.count(II) &&
1398 "should get invoke with precomputed state");
1399 LabelToStateMap[InvokeBegin] = std::make_pair(x&: InvokeStateMap[II], y&: InvokeEnd);
1400}
1401
1402void WinEHFuncInfo::addIPToStateRange(int State, MCSymbol* InvokeBegin,
1403 MCSymbol* InvokeEnd) {
1404 LabelToStateMap[InvokeBegin] = std::make_pair(x&: State, y&: InvokeEnd);
1405}
1406
1407WinEHFuncInfo::WinEHFuncInfo() = default;
1408