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. It snifs the personality function to see which kind of
12 // preparation is necessary. If the personality function uses the Itanium LSDA,
13 // this pass delegates to the DWARF EH preparation pass.
15 //===----------------------------------------------------------------------===//
17 #include "llvm/CodeGen/Passes.h"
18 #include "llvm/ADT/MapVector.h"
19 #include "llvm/ADT/STLExtras.h"
20 #include "llvm/ADT/SmallSet.h"
21 #include "llvm/ADT/TinyPtrVector.h"
22 #include "llvm/Analysis/LibCallSemantics.h"
23 #include "llvm/CodeGen/WinEHFuncInfo.h"
24 #include "llvm/IR/Dominators.h"
25 #include "llvm/IR/Function.h"
26 #include "llvm/IR/IRBuilder.h"
27 #include "llvm/IR/Instructions.h"
28 #include "llvm/IR/IntrinsicInst.h"
29 #include "llvm/IR/Module.h"
30 #include "llvm/IR/PatternMatch.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/Transforms/Utils/BasicBlockUtils.h"
36 #include "llvm/Transforms/Utils/Cloning.h"
37 #include "llvm/Transforms/Utils/Local.h"
38 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
42 using namespace llvm::PatternMatch;
44 #define DEBUG_TYPE "winehprepare"
48 // This map is used to model frame variable usage during outlining, to
49 // construct a structure type to hold the frame variables in a frame
50 // allocation block, and to remap the frame variable allocas (including
51 // spill locations as needed) to GEPs that get the variable from the
52 // frame allocation structure.
53 typedef MapVector<Value *, TinyPtrVector<AllocaInst *>> FrameVarInfoMap;
55 // TinyPtrVector cannot hold nullptr, so we need our own sentinel that isn't
57 AllocaInst *getCatchObjectSentinel() {
58 return static_cast<AllocaInst *>(nullptr) + 1;
61 typedef SmallSet<BasicBlock *, 4> VisitedBlockSet;
63 class LandingPadActions;
66 typedef DenseMap<const BasicBlock *, CatchHandler *> CatchHandlerMapTy;
67 typedef DenseMap<const BasicBlock *, CleanupHandler *> CleanupHandlerMapTy;
69 class WinEHPrepare : public FunctionPass {
71 static char ID; // Pass identification, replacement for typeid.
72 WinEHPrepare(const TargetMachine *TM = nullptr)
73 : FunctionPass(ID), DT(nullptr) {}
75 bool runOnFunction(Function &Fn) override;
77 bool doFinalization(Module &M) override;
79 void getAnalysisUsage(AnalysisUsage &AU) const override;
81 const char *getPassName() const override {
82 return "Windows exception handling preparation";
86 bool prepareExceptionHandlers(Function &F,
87 SmallVectorImpl<LandingPadInst *> &LPads);
88 void promoteLandingPadValues(LandingPadInst *LPad);
89 void completeNestedLandingPad(Function *ParentFn,
90 LandingPadInst *OutlinedLPad,
91 const LandingPadInst *OriginalLPad,
92 FrameVarInfoMap &VarInfo);
93 bool outlineHandler(ActionHandler *Action, Function *SrcFn,
94 LandingPadInst *LPad, BasicBlock *StartBB,
95 FrameVarInfoMap &VarInfo);
96 void addStubInvokeToHandlerIfNeeded(Function *Handler, Value *PersonalityFn);
98 void mapLandingPadBlocks(LandingPadInst *LPad, LandingPadActions &Actions);
99 CatchHandler *findCatchHandler(BasicBlock *BB, BasicBlock *&NextBB,
100 VisitedBlockSet &VisitedBlocks);
101 void findCleanupHandlers(LandingPadActions &Actions, BasicBlock *StartBB,
104 void processSEHCatchHandler(CatchHandler *Handler, BasicBlock *StartBB);
106 // All fields are reset by runOnFunction.
108 EHPersonality Personality;
109 CatchHandlerMapTy CatchHandlerMap;
110 CleanupHandlerMapTy CleanupHandlerMap;
111 DenseMap<const LandingPadInst *, LandingPadMap> LPadMaps;
113 // This maps landing pad instructions found in outlined handlers to
114 // the landing pad instruction in the parent function from which they
115 // were cloned. The cloned/nested landing pad is used as the key
116 // because the landing pad may be cloned into multiple handlers.
117 // This map will be used to add the llvm.eh.actions call to the nested
118 // landing pads after all handlers have been outlined.
119 DenseMap<LandingPadInst *, const LandingPadInst *> NestedLPtoOriginalLP;
121 // This maps blocks in the parent function which are destinations of
122 // catch handlers to cloned blocks in (other) outlined handlers. This
123 // handles the case where a nested landing pads has a catch handler that
124 // returns to a handler function rather than the parent function.
125 // The original block is used as the key here because there should only
126 // ever be one handler function from which the cloned block is not pruned.
127 // The original block will be pruned from the parent function after all
128 // handlers have been outlined. This map will be used to adjust the
129 // return instructions of handlers which return to the block that was
130 // outlined into a handler. This is done after all handlers have been
131 // outlined but before the outlined code is pruned from the parent function.
132 DenseMap<const BasicBlock *, BasicBlock *> LPadTargetBlocks;
135 class WinEHFrameVariableMaterializer : public ValueMaterializer {
137 WinEHFrameVariableMaterializer(Function *OutlinedFn,
138 FrameVarInfoMap &FrameVarInfo);
139 ~WinEHFrameVariableMaterializer() override {}
141 Value *materializeValueFor(Value *V) override;
143 void escapeCatchObject(Value *V);
146 FrameVarInfoMap &FrameVarInfo;
150 class LandingPadMap {
152 LandingPadMap() : OriginLPad(nullptr) {}
153 void mapLandingPad(const LandingPadInst *LPad);
155 bool isInitialized() { return OriginLPad != nullptr; }
157 bool isOriginLandingPadBlock(const BasicBlock *BB) const;
158 bool isLandingPadSpecificInst(const Instruction *Inst) const;
160 void remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
161 Value *SelectorValue) const;
164 const LandingPadInst *OriginLPad;
165 // We will normally only see one of each of these instructions, but
166 // if more than one occurs for some reason we can handle that.
167 TinyPtrVector<const ExtractValueInst *> ExtractedEHPtrs;
168 TinyPtrVector<const ExtractValueInst *> ExtractedSelectors;
171 class WinEHCloningDirectorBase : public CloningDirector {
173 WinEHCloningDirectorBase(Function *HandlerFn, FrameVarInfoMap &VarInfo,
174 LandingPadMap &LPadMap)
175 : Materializer(HandlerFn, VarInfo),
176 SelectorIDType(Type::getInt32Ty(HandlerFn->getContext())),
177 Int8PtrType(Type::getInt8PtrTy(HandlerFn->getContext())),
180 CloningAction handleInstruction(ValueToValueMapTy &VMap,
181 const Instruction *Inst,
182 BasicBlock *NewBB) override;
184 virtual CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
185 const Instruction *Inst,
186 BasicBlock *NewBB) = 0;
187 virtual CloningAction handleEndCatch(ValueToValueMapTy &VMap,
188 const Instruction *Inst,
189 BasicBlock *NewBB) = 0;
190 virtual CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
191 const Instruction *Inst,
192 BasicBlock *NewBB) = 0;
193 virtual CloningAction handleInvoke(ValueToValueMapTy &VMap,
194 const InvokeInst *Invoke,
195 BasicBlock *NewBB) = 0;
196 virtual CloningAction handleResume(ValueToValueMapTy &VMap,
197 const ResumeInst *Resume,
198 BasicBlock *NewBB) = 0;
199 virtual CloningAction handleCompare(ValueToValueMapTy &VMap,
200 const CmpInst *Compare,
201 BasicBlock *NewBB) = 0;
202 virtual CloningAction handleLandingPad(ValueToValueMapTy &VMap,
203 const LandingPadInst *LPad,
204 BasicBlock *NewBB) = 0;
206 ValueMaterializer *getValueMaterializer() override { return &Materializer; }
209 WinEHFrameVariableMaterializer Materializer;
210 Type *SelectorIDType;
212 LandingPadMap &LPadMap;
215 class WinEHCatchDirector : public WinEHCloningDirectorBase {
218 Function *CatchFn, Value *Selector, FrameVarInfoMap &VarInfo,
219 LandingPadMap &LPadMap,
220 DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPads)
221 : WinEHCloningDirectorBase(CatchFn, VarInfo, LPadMap),
222 CurrentSelector(Selector->stripPointerCasts()),
223 ExceptionObjectVar(nullptr), NestedLPtoOriginalLP(NestedLPads) {}
225 CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
226 const Instruction *Inst,
227 BasicBlock *NewBB) override;
228 CloningAction handleEndCatch(ValueToValueMapTy &VMap, const Instruction *Inst,
229 BasicBlock *NewBB) override;
230 CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
231 const Instruction *Inst,
232 BasicBlock *NewBB) override;
233 CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
234 BasicBlock *NewBB) override;
235 CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
236 BasicBlock *NewBB) override;
237 CloningAction handleCompare(ValueToValueMapTy &VMap,
238 const CmpInst *Compare, BasicBlock *NewBB) override;
239 CloningAction handleLandingPad(ValueToValueMapTy &VMap,
240 const LandingPadInst *LPad,
241 BasicBlock *NewBB) override;
243 Value *getExceptionVar() { return ExceptionObjectVar; }
244 TinyPtrVector<BasicBlock *> &getReturnTargets() { return ReturnTargets; }
247 Value *CurrentSelector;
249 Value *ExceptionObjectVar;
250 TinyPtrVector<BasicBlock *> ReturnTargets;
252 // This will be a reference to the field of the same name in the WinEHPrepare
253 // object which instantiates this WinEHCatchDirector object.
254 DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPtoOriginalLP;
257 class WinEHCleanupDirector : public WinEHCloningDirectorBase {
259 WinEHCleanupDirector(Function *CleanupFn, FrameVarInfoMap &VarInfo,
260 LandingPadMap &LPadMap)
261 : WinEHCloningDirectorBase(CleanupFn, VarInfo, LPadMap) {}
263 CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
264 const Instruction *Inst,
265 BasicBlock *NewBB) override;
266 CloningAction handleEndCatch(ValueToValueMapTy &VMap, const Instruction *Inst,
267 BasicBlock *NewBB) override;
268 CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
269 const Instruction *Inst,
270 BasicBlock *NewBB) override;
271 CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
272 BasicBlock *NewBB) override;
273 CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
274 BasicBlock *NewBB) override;
275 CloningAction handleCompare(ValueToValueMapTy &VMap,
276 const CmpInst *Compare, BasicBlock *NewBB) override;
277 CloningAction handleLandingPad(ValueToValueMapTy &VMap,
278 const LandingPadInst *LPad,
279 BasicBlock *NewBB) override;
282 class LandingPadActions {
284 LandingPadActions() : HasCleanupHandlers(false) {}
286 void insertCatchHandler(CatchHandler *Action) { Actions.push_back(Action); }
287 void insertCleanupHandler(CleanupHandler *Action) {
288 Actions.push_back(Action);
289 HasCleanupHandlers = true;
292 bool includesCleanup() const { return HasCleanupHandlers; }
294 SmallVectorImpl<ActionHandler *> &actions() { return Actions; }
295 SmallVectorImpl<ActionHandler *>::iterator begin() { return Actions.begin(); }
296 SmallVectorImpl<ActionHandler *>::iterator end() { return Actions.end(); }
299 // Note that this class does not own the ActionHandler objects in this vector.
300 // The ActionHandlers are owned by the CatchHandlerMap and CleanupHandlerMap
301 // in the WinEHPrepare class.
302 SmallVector<ActionHandler *, 4> Actions;
303 bool HasCleanupHandlers;
306 } // end anonymous namespace
308 char WinEHPrepare::ID = 0;
309 INITIALIZE_TM_PASS(WinEHPrepare, "winehprepare", "Prepare Windows exceptions",
312 FunctionPass *llvm::createWinEHPass(const TargetMachine *TM) {
313 return new WinEHPrepare(TM);
316 // FIXME: Remove this once the backend can handle the prepared IR.
318 SEHPrepare("sehprepare", cl::Hidden,
319 cl::desc("Prepare functions with SEH personalities"));
321 bool WinEHPrepare::runOnFunction(Function &Fn) {
322 SmallVector<LandingPadInst *, 4> LPads;
323 SmallVector<ResumeInst *, 4> Resumes;
324 for (BasicBlock &BB : Fn) {
325 if (auto *LP = BB.getLandingPadInst())
327 if (auto *Resume = dyn_cast<ResumeInst>(BB.getTerminator()))
328 Resumes.push_back(Resume);
331 // No need to prepare functions that lack landing pads.
335 // Classify the personality to see what kind of preparation we need.
336 Personality = classifyEHPersonality(LPads.back()->getPersonalityFn());
338 // Do nothing if this is not an MSVC personality.
339 if (!isMSVCEHPersonality(Personality))
342 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
344 if (isAsynchronousEHPersonality(Personality) && !SEHPrepare) {
345 // Replace all resume instructions with unreachable.
346 // FIXME: Remove this once the backend can handle the prepared IR.
347 for (ResumeInst *Resume : Resumes) {
348 IRBuilder<>(Resume).CreateUnreachable();
349 Resume->eraseFromParent();
354 // If there were any landing pads, prepareExceptionHandlers will make changes.
355 prepareExceptionHandlers(Fn, LPads);
359 bool WinEHPrepare::doFinalization(Module &M) { return false; }
361 void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {
362 AU.addRequired<DominatorTreeWrapperPass>();
365 bool WinEHPrepare::prepareExceptionHandlers(
366 Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
367 // These containers are used to re-map frame variables that are used in
368 // outlined catch and cleanup handlers. They will be populated as the
369 // handlers are outlined.
370 FrameVarInfoMap FrameVarInfo;
372 bool HandlersOutlined = false;
374 Module *M = F.getParent();
375 LLVMContext &Context = M->getContext();
377 // Create a new function to receive the handler contents.
378 PointerType *Int8PtrType = Type::getInt8PtrTy(Context);
379 Type *Int32Type = Type::getInt32Ty(Context);
380 Function *ActionIntrin = Intrinsic::getDeclaration(M, Intrinsic::eh_actions);
382 for (LandingPadInst *LPad : LPads) {
383 // Look for evidence that this landingpad has already been processed.
384 bool LPadHasActionList = false;
385 BasicBlock *LPadBB = LPad->getParent();
386 for (Instruction &Inst : *LPadBB) {
387 if (auto *IntrinCall = dyn_cast<IntrinsicInst>(&Inst)) {
388 if (IntrinCall->getIntrinsicID() == Intrinsic::eh_actions) {
389 LPadHasActionList = true;
393 // FIXME: This is here to help with the development of nested landing pad
394 // outlining. It should be removed when that is finished.
395 if (isa<UnreachableInst>(Inst)) {
396 LPadHasActionList = true;
401 // If we've already outlined the handlers for this landingpad,
402 // there's nothing more to do here.
403 if (LPadHasActionList)
406 // If either of the values in the aggregate returned by the landing pad is
407 // extracted and stored to memory, promote the stored value to a register.
408 promoteLandingPadValues(LPad);
410 LandingPadActions Actions;
411 mapLandingPadBlocks(LPad, Actions);
413 HandlersOutlined |= !Actions.actions().empty();
414 for (ActionHandler *Action : Actions) {
415 if (Action->hasBeenProcessed())
417 BasicBlock *StartBB = Action->getStartBlock();
419 // SEH doesn't do any outlining for catches. Instead, pass the handler
420 // basic block addr to llvm.eh.actions and list the block as a return
422 if (isAsynchronousEHPersonality(Personality)) {
423 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
424 processSEHCatchHandler(CatchAction, StartBB);
429 outlineHandler(Action, &F, LPad, StartBB, FrameVarInfo);
432 // Replace the landing pad with a new llvm.eh.action based landing pad.
433 BasicBlock *NewLPadBB = BasicBlock::Create(Context, "lpad", &F, LPadBB);
434 assert(!isa<PHINode>(LPadBB->begin()));
435 auto *NewLPad = cast<LandingPadInst>(LPad->clone());
436 NewLPadBB->getInstList().push_back(NewLPad);
437 while (!pred_empty(LPadBB)) {
438 auto *pred = *pred_begin(LPadBB);
439 InvokeInst *Invoke = cast<InvokeInst>(pred->getTerminator());
440 Invoke->setUnwindDest(NewLPadBB);
443 // If anyone is still using the old landingpad value, just give them undef
444 // instead. The eh pointer and selector values are not real.
445 LPad->replaceAllUsesWith(UndefValue::get(LPad->getType()));
447 // Replace the mapping of any nested landing pad that previously mapped
448 // to this landing pad with a referenced to the cloned version.
449 for (auto &LPadPair : NestedLPtoOriginalLP) {
450 const LandingPadInst *OriginalLPad = LPadPair.second;
451 if (OriginalLPad == LPad) {
452 LPadPair.second = NewLPad;
456 // Replace uses of the old lpad in phis with this block and delete the old
458 LPadBB->replaceSuccessorsPhiUsesWith(NewLPadBB);
459 LPadBB->getTerminator()->eraseFromParent();
460 new UnreachableInst(LPadBB->getContext(), LPadBB);
462 // Add a call to describe the actions for this landing pad.
463 std::vector<Value *> ActionArgs;
464 for (ActionHandler *Action : Actions) {
465 // Action codes from docs are: 0 cleanup, 1 catch.
466 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
467 ActionArgs.push_back(ConstantInt::get(Int32Type, 1));
468 ActionArgs.push_back(CatchAction->getSelector());
469 // Find the frame escape index of the exception object alloca in the
471 int FrameEscapeIdx = -1;
472 Value *EHObj = const_cast<Value *>(CatchAction->getExceptionVar());
473 if (EHObj && !isa<ConstantPointerNull>(EHObj)) {
474 auto I = FrameVarInfo.find(EHObj);
475 assert(I != FrameVarInfo.end() &&
476 "failed to map llvm.eh.begincatch var");
477 FrameEscapeIdx = std::distance(FrameVarInfo.begin(), I);
479 ActionArgs.push_back(ConstantInt::get(Int32Type, FrameEscapeIdx));
481 ActionArgs.push_back(ConstantInt::get(Int32Type, 0));
483 ActionArgs.push_back(Action->getHandlerBlockOrFunc());
486 CallInst::Create(ActionIntrin, ActionArgs, "recover", NewLPadBB);
488 // Add an indirect branch listing possible successors of the catch handlers.
489 IndirectBrInst *Branch = IndirectBrInst::Create(Recover, 0, NewLPadBB);
490 for (ActionHandler *Action : Actions) {
491 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
492 for (auto *Target : CatchAction->getReturnTargets()) {
493 Branch->addDestination(Target);
497 } // End for each landingpad
499 // If nothing got outlined, there is no more processing to be done.
500 if (!HandlersOutlined)
503 // Replace any nested landing pad stubs with the correct action handler.
504 // This must be done before we remove unreachable blocks because it
505 // cleans up references to outlined blocks that will be deleted.
506 for (auto &LPadPair : NestedLPtoOriginalLP)
507 completeNestedLandingPad(&F, LPadPair.first, LPadPair.second, FrameVarInfo);
508 NestedLPtoOriginalLP.clear();
510 F.addFnAttr("wineh-parent", F.getName());
512 // Delete any blocks that were only used by handlers that were outlined above.
513 removeUnreachableBlocks(F);
515 BasicBlock *Entry = &F.getEntryBlock();
516 IRBuilder<> Builder(F.getParent()->getContext());
517 Builder.SetInsertPoint(Entry->getFirstInsertionPt());
519 Function *FrameEscapeFn =
520 Intrinsic::getDeclaration(M, Intrinsic::frameescape);
521 Function *RecoverFrameFn =
522 Intrinsic::getDeclaration(M, Intrinsic::framerecover);
524 // Finally, replace all of the temporary allocas for frame variables used in
525 // the outlined handlers with calls to llvm.framerecover.
526 BasicBlock::iterator II = Entry->getFirstInsertionPt();
527 Instruction *AllocaInsertPt = II;
528 SmallVector<Value *, 8> AllocasToEscape;
529 for (auto &VarInfoEntry : FrameVarInfo) {
530 Value *ParentVal = VarInfoEntry.first;
531 TinyPtrVector<AllocaInst *> &Allocas = VarInfoEntry.second;
533 // If the mapped value isn't already an alloca, we need to spill it if it
534 // is a computed value or copy it if it is an argument.
535 AllocaInst *ParentAlloca = dyn_cast<AllocaInst>(ParentVal);
537 if (auto *Arg = dyn_cast<Argument>(ParentVal)) {
538 // Lower this argument to a copy and then demote that to the stack.
539 // We can't just use the argument location because the handler needs
540 // it to be in the frame allocation block.
541 // Use 'select i8 true, %arg, undef' to simulate a 'no-op' instruction.
542 Value *TrueValue = ConstantInt::getTrue(Context);
543 Value *UndefValue = UndefValue::get(Arg->getType());
545 SelectInst::Create(TrueValue, Arg, UndefValue,
546 Arg->getName() + ".tmp", AllocaInsertPt);
547 Arg->replaceAllUsesWith(SI);
548 // Reset the select operand, because it was clobbered by the RAUW above.
549 SI->setOperand(1, Arg);
550 ParentAlloca = DemoteRegToStack(*SI, true, SI);
551 } else if (auto *PN = dyn_cast<PHINode>(ParentVal)) {
552 ParentAlloca = DemotePHIToStack(PN, AllocaInsertPt);
554 Instruction *ParentInst = cast<Instruction>(ParentVal);
555 // FIXME: This is a work-around to temporarily handle the case where an
556 // instruction that is only used in handlers is not sunk.
557 // Without uses, DemoteRegToStack would just eliminate the value.
558 // This will fail if ParentInst is an invoke.
559 if (ParentInst->getNumUses() == 0) {
560 BasicBlock::iterator InsertPt = ParentInst;
563 new AllocaInst(ParentInst->getType(), nullptr,
564 ParentInst->getName() + ".reg2mem",
566 new StoreInst(ParentInst, ParentAlloca, InsertPt);
568 ParentAlloca = DemoteRegToStack(*ParentInst, true, AllocaInsertPt);
573 // FIXME: We should try to sink unescaped allocas from the parent frame into
574 // the child frame. If the alloca is escaped, we have to use the lifetime
575 // markers to ensure that the alloca is only live within the child frame.
577 // Add this alloca to the list of things to escape.
578 AllocasToEscape.push_back(ParentAlloca);
580 // Next replace all outlined allocas that are mapped to it.
581 for (AllocaInst *TempAlloca : Allocas) {
582 if (TempAlloca == getCatchObjectSentinel())
583 continue; // Skip catch parameter sentinels.
584 Function *HandlerFn = TempAlloca->getParent()->getParent();
585 // FIXME: Sink this GEP into the blocks where it is used.
586 Builder.SetInsertPoint(TempAlloca);
587 Builder.SetCurrentDebugLocation(TempAlloca->getDebugLoc());
588 Value *RecoverArgs[] = {
589 Builder.CreateBitCast(&F, Int8PtrType, ""),
590 &(HandlerFn->getArgumentList().back()),
591 llvm::ConstantInt::get(Int32Type, AllocasToEscape.size() - 1)};
592 Value *RecoveredAlloca = Builder.CreateCall(RecoverFrameFn, RecoverArgs);
593 // Add a pointer bitcast if the alloca wasn't an i8.
594 if (RecoveredAlloca->getType() != TempAlloca->getType()) {
595 RecoveredAlloca->setName(Twine(TempAlloca->getName()) + ".i8");
597 Builder.CreateBitCast(RecoveredAlloca, TempAlloca->getType());
599 TempAlloca->replaceAllUsesWith(RecoveredAlloca);
600 TempAlloca->removeFromParent();
601 RecoveredAlloca->takeName(TempAlloca);
604 } // End for each FrameVarInfo entry.
606 // Insert 'call void (...)* @llvm.frameescape(...)' at the end of the entry
608 Builder.SetInsertPoint(&F.getEntryBlock().back());
609 Builder.CreateCall(FrameEscapeFn, AllocasToEscape);
611 // Clean up the handler action maps we created for this function
612 DeleteContainerSeconds(CatchHandlerMap);
613 CatchHandlerMap.clear();
614 DeleteContainerSeconds(CleanupHandlerMap);
615 CleanupHandlerMap.clear();
617 return HandlersOutlined;
620 void WinEHPrepare::promoteLandingPadValues(LandingPadInst *LPad) {
621 // If the return values of the landing pad instruction are extracted and
622 // stored to memory, we want to promote the store locations to reg values.
623 SmallVector<AllocaInst *, 2> EHAllocas;
625 // The landingpad instruction returns an aggregate value. Typically, its
626 // value will be passed to a pair of extract value instructions and the
627 // results of those extracts are often passed to store instructions.
628 // In unoptimized code the stored value will often be loaded and then stored
630 for (auto *U : LPad->users()) {
631 ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
635 for (auto *EU : Extract->users()) {
636 if (auto *Store = dyn_cast<StoreInst>(EU)) {
637 auto *AV = cast<AllocaInst>(Store->getPointerOperand());
638 EHAllocas.push_back(AV);
643 // We can't do this without a dominator tree.
646 if (!EHAllocas.empty()) {
647 PromoteMemToReg(EHAllocas, *DT);
651 // After promotion, some extracts may be trivially dead. Remove them.
652 SmallVector<Value *, 4> Users(LPad->user_begin(), LPad->user_end());
653 for (auto *U : Users)
654 RecursivelyDeleteTriviallyDeadInstructions(U);
657 void WinEHPrepare::completeNestedLandingPad(Function *ParentFn,
658 LandingPadInst *OutlinedLPad,
659 const LandingPadInst *OriginalLPad,
660 FrameVarInfoMap &FrameVarInfo) {
661 // Get the nested block and erase the unreachable instruction that was
662 // temporarily inserted as its terminator.
663 LLVMContext &Context = ParentFn->getContext();
664 BasicBlock *OutlinedBB = OutlinedLPad->getParent();
665 assert(isa<UnreachableInst>(OutlinedBB->getTerminator()));
666 OutlinedBB->getTerminator()->eraseFromParent();
667 // That should leave OutlinedLPad as the last instruction in its block.
668 assert(&OutlinedBB->back() == OutlinedLPad);
670 // The original landing pad will have already had its action intrinsic
671 // built by the outlining loop. We need to clone that into the outlined
672 // location. It may also be necessary to add references to the exception
673 // variables to the outlined handler in which this landing pad is nested
674 // and remap return instructions in the nested handlers that should return
675 // to an address in the outlined handler.
676 Function *OutlinedHandlerFn = OutlinedBB->getParent();
677 BasicBlock::const_iterator II = OriginalLPad;
679 // The instruction after the landing pad should now be a call to eh.actions.
680 const Instruction *Recover = II;
681 assert(match(Recover, m_Intrinsic<Intrinsic::eh_actions>()));
682 IntrinsicInst *EHActions = cast<IntrinsicInst>(Recover->clone());
684 // Remap the exception variables into the outlined function.
685 WinEHFrameVariableMaterializer Materializer(OutlinedHandlerFn, FrameVarInfo);
686 SmallVector<BlockAddress *, 4> ActionTargets;
687 SmallVector<ActionHandler *, 4> ActionList;
688 parseEHActions(EHActions, ActionList);
689 for (auto *Action : ActionList) {
690 auto *Catch = dyn_cast<CatchHandler>(Action);
693 // The dyn_cast to function here selects C++ catch handlers and skips
694 // SEH catch handlers.
695 auto *Handler = dyn_cast<Function>(Catch->getHandlerBlockOrFunc());
698 // Visit all the return instructions, looking for places that return
699 // to a location within OutlinedHandlerFn.
700 for (BasicBlock &NestedHandlerBB : *Handler) {
701 auto *Ret = dyn_cast<ReturnInst>(NestedHandlerBB.getTerminator());
705 // Handler functions must always return a block address.
706 BlockAddress *BA = cast<BlockAddress>(Ret->getReturnValue());
707 // The original target will have been in the main parent function,
708 // but if it is the address of a block that has been outlined, it
709 // should be a block that was outlined into OutlinedHandlerFn.
710 assert(BA->getFunction() == ParentFn);
712 // Ignore targets that aren't part of OutlinedHandlerFn.
713 if (!LPadTargetBlocks.count(BA->getBasicBlock()))
716 // If the return value is the address ofF a block that we
717 // previously outlined into the parent handler function, replace
718 // the return instruction and add the mapped target to the list
719 // of possible return addresses.
720 BasicBlock *MappedBB = LPadTargetBlocks[BA->getBasicBlock()];
721 assert(MappedBB->getParent() == OutlinedHandlerFn);
722 BlockAddress *NewBA = BlockAddress::get(OutlinedHandlerFn, MappedBB);
723 Ret->eraseFromParent();
724 ReturnInst::Create(Context, NewBA, &NestedHandlerBB);
725 ActionTargets.push_back(NewBA);
728 DeleteContainerPointers(ActionList);
730 OutlinedBB->getInstList().push_back(EHActions);
732 // Insert an indirect branch into the outlined landing pad BB.
733 IndirectBrInst *IBr = IndirectBrInst::Create(EHActions, 0, OutlinedBB);
734 // Add the previously collected action targets.
735 for (auto *Target : ActionTargets)
736 IBr->addDestination(Target->getBasicBlock());
739 // This function examines a block to determine whether the block ends with a
740 // conditional branch to a catch handler based on a selector comparison.
741 // This function is used both by the WinEHPrepare::findSelectorComparison() and
742 // WinEHCleanupDirector::handleTypeIdFor().
743 static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler,
744 Constant *&Selector, BasicBlock *&NextBB) {
745 ICmpInst::Predicate Pred;
746 BasicBlock *TBB, *FBB;
749 if (!match(BB->getTerminator(),
750 m_Br(m_ICmp(Pred, m_Value(LHS), m_Value(RHS)), TBB, FBB)))
754 m_Intrinsic<Intrinsic::eh_typeid_for>(m_Constant(Selector))) &&
755 !match(RHS, m_Intrinsic<Intrinsic::eh_typeid_for>(m_Constant(Selector))))
758 if (Pred == CmpInst::ICMP_EQ) {
764 if (Pred == CmpInst::ICMP_NE) {
773 static bool isCatchBlock(BasicBlock *BB) {
774 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
776 if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_begincatch>()))
782 static BasicBlock *createStubLandingPad(Function *Handler,
783 Value *PersonalityFn) {
784 // FIXME: Finish this!
785 LLVMContext &Context = Handler->getContext();
786 BasicBlock *StubBB = BasicBlock::Create(Context, "stub");
787 Handler->getBasicBlockList().push_back(StubBB);
788 IRBuilder<> Builder(StubBB);
789 LandingPadInst *LPad = Builder.CreateLandingPad(
790 llvm::StructType::get(Type::getInt8PtrTy(Context),
791 Type::getInt32Ty(Context), nullptr),
793 LPad->setCleanup(true);
794 Builder.CreateUnreachable();
798 // Cycles through the blocks in an outlined handler function looking for an
799 // invoke instruction and inserts an invoke of llvm.donothing with an empty
800 // landing pad if none is found. The code that generates the .xdata tables for
801 // the handler needs at least one landing pad to identify the parent function's
803 void WinEHPrepare::addStubInvokeToHandlerIfNeeded(Function *Handler,
804 Value *PersonalityFn) {
805 ReturnInst *Ret = nullptr;
806 for (BasicBlock &BB : *Handler) {
807 TerminatorInst *Terminator = BB.getTerminator();
808 // If we find an invoke, there is nothing to be done.
809 auto *II = dyn_cast<InvokeInst>(Terminator);
812 // If we've already recorded a return instruction, keep looking for invokes.
815 // If we haven't recorded a return instruction yet, try this terminator.
816 Ret = dyn_cast<ReturnInst>(Terminator);
819 // If we got this far, the handler contains no invokes. We should have seen
820 // at least one return. We'll insert an invoke of llvm.donothing ahead of
823 BasicBlock *OldRetBB = Ret->getParent();
824 BasicBlock *NewRetBB = SplitBlock(OldRetBB, Ret);
825 // SplitBlock adds an unconditional branch instruction at the end of the
826 // parent block. We want to replace that with an invoke call, so we can
828 OldRetBB->getTerminator()->eraseFromParent();
829 BasicBlock *StubLandingPad = createStubLandingPad(Handler, PersonalityFn);
831 Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::donothing);
832 InvokeInst::Create(F, NewRetBB, StubLandingPad, None, "", OldRetBB);
835 bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn,
836 LandingPadInst *LPad, BasicBlock *StartBB,
837 FrameVarInfoMap &VarInfo) {
838 Module *M = SrcFn->getParent();
839 LLVMContext &Context = M->getContext();
841 // Create a new function to receive the handler contents.
842 Type *Int8PtrType = Type::getInt8PtrTy(Context);
843 std::vector<Type *> ArgTys;
844 ArgTys.push_back(Int8PtrType);
845 ArgTys.push_back(Int8PtrType);
847 if (Action->getType() == Catch) {
848 FunctionType *FnType = FunctionType::get(Int8PtrType, ArgTys, false);
849 Handler = Function::Create(FnType, GlobalVariable::InternalLinkage,
850 SrcFn->getName() + ".catch", M);
852 FunctionType *FnType =
853 FunctionType::get(Type::getVoidTy(Context), ArgTys, false);
854 Handler = Function::Create(FnType, GlobalVariable::InternalLinkage,
855 SrcFn->getName() + ".cleanup", M);
858 Handler->addFnAttr("wineh-parent", SrcFn->getName());
860 // Generate a standard prolog to setup the frame recovery structure.
861 IRBuilder<> Builder(Context);
862 BasicBlock *Entry = BasicBlock::Create(Context, "entry");
863 Handler->getBasicBlockList().push_front(Entry);
864 Builder.SetInsertPoint(Entry);
865 Builder.SetCurrentDebugLocation(LPad->getDebugLoc());
867 std::unique_ptr<WinEHCloningDirectorBase> Director;
869 ValueToValueMapTy VMap;
871 LandingPadMap &LPadMap = LPadMaps[LPad];
872 if (!LPadMap.isInitialized())
873 LPadMap.mapLandingPad(LPad);
874 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
875 Constant *Sel = CatchAction->getSelector();
876 Director.reset(new WinEHCatchDirector(Handler, Sel, VarInfo, LPadMap,
877 NestedLPtoOriginalLP));
878 LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
879 ConstantInt::get(Type::getInt32Ty(Context), 1));
881 Director.reset(new WinEHCleanupDirector(Handler, VarInfo, LPadMap));
882 LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
883 UndefValue::get(Type::getInt32Ty(Context)));
886 SmallVector<ReturnInst *, 8> Returns;
887 ClonedCodeInfo OutlinedFunctionInfo;
889 // If the start block contains PHI nodes, we need to map them.
890 BasicBlock::iterator II = StartBB->begin();
891 while (auto *PN = dyn_cast<PHINode>(II)) {
893 // Look for PHI values that we have already mapped (such as the selector).
894 for (Value *Val : PN->incoming_values()) {
895 if (VMap.count(Val)) {
896 VMap[PN] = VMap[Val];
900 // If we didn't find a match for this value, map it as an undef.
902 VMap[PN] = UndefValue::get(PN->getType());
907 // Skip over PHIs and, if applicable, landingpad instructions.
908 II = StartBB->getFirstInsertionPt();
910 CloneAndPruneIntoFromInst(Handler, SrcFn, II, VMap,
911 /*ModuleLevelChanges=*/false, Returns, "",
912 &OutlinedFunctionInfo, Director.get());
914 // Move all the instructions in the first cloned block into our entry block.
915 BasicBlock *FirstClonedBB = std::next(Function::iterator(Entry));
916 Entry->getInstList().splice(Entry->end(), FirstClonedBB->getInstList());
917 FirstClonedBB->eraseFromParent();
919 // Make sure we can identify the handler's personality later.
920 addStubInvokeToHandlerIfNeeded(Handler, LPad->getPersonalityFn());
922 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
923 WinEHCatchDirector *CatchDirector =
924 reinterpret_cast<WinEHCatchDirector *>(Director.get());
925 CatchAction->setExceptionVar(CatchDirector->getExceptionVar());
926 CatchAction->setReturnTargets(CatchDirector->getReturnTargets());
928 // Look for blocks that are not part of the landing pad that we just
929 // outlined but terminate with a call to llvm.eh.endcatch and a
930 // branch to a block that is in the handler we just outlined.
931 // These blocks will be part of a nested landing pad that intends to
932 // return to an address in this handler. This case is best handled
933 // after both landing pads have been outlined, so for now we'll just
934 // save the association of the blocks in LPadTargetBlocks. The
935 // return instructions which are created from these branches will be
936 // replaced after all landing pads have been outlined.
937 for (const auto MapEntry : VMap) {
938 // VMap maps all values and blocks that were just cloned, but dead
939 // blocks which were pruned will map to nullptr.
940 if (!isa<BasicBlock>(MapEntry.first) || MapEntry.second == nullptr)
942 const BasicBlock *MappedBB = cast<BasicBlock>(MapEntry.first);
943 for (auto *Pred : predecessors(const_cast<BasicBlock *>(MappedBB))) {
944 auto *Branch = dyn_cast<BranchInst>(Pred->getTerminator());
945 if (!Branch || !Branch->isUnconditional() || Pred->size() <= 1)
947 BasicBlock::iterator II = const_cast<BranchInst *>(Branch);
949 if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_endcatch>())) {
950 // This would indicate that a nested landing pad wants to return
951 // to a block that is outlined into two different handlers.
952 assert(!LPadTargetBlocks.count(MappedBB));
953 LPadTargetBlocks[MappedBB] = cast<BasicBlock>(MapEntry.second);
957 } // End if (CatchAction)
959 Action->setHandlerBlockOrFunc(Handler);
964 /// This BB must end in a selector dispatch. All we need to do is pass the
965 /// handler block to llvm.eh.actions and list it as a possible indirectbr
967 void WinEHPrepare::processSEHCatchHandler(CatchHandler *CatchAction,
968 BasicBlock *StartBB) {
969 BasicBlock *HandlerBB;
972 bool Res = isSelectorDispatch(StartBB, HandlerBB, Selector, NextBB);
974 // If this was EH dispatch, this must be a conditional branch to the handler
976 // FIXME: Handle instructions in the dispatch block. Currently we drop them,
977 // leading to crashes if some optimization hoists stuff here.
978 assert(CatchAction->getSelector() && HandlerBB &&
979 "expected catch EH dispatch");
981 // This must be a catch-all. Split the block after the landingpad.
982 assert(CatchAction->getSelector()->isNullValue() && "expected catch-all");
984 StartBB->splitBasicBlock(StartBB->getFirstInsertionPt(), "catch.all");
986 CatchAction->setHandlerBlockOrFunc(BlockAddress::get(HandlerBB));
987 TinyPtrVector<BasicBlock *> Targets(HandlerBB);
988 CatchAction->setReturnTargets(Targets);
991 void LandingPadMap::mapLandingPad(const LandingPadInst *LPad) {
992 // Each instance of this class should only ever be used to map a single
994 assert(OriginLPad == nullptr || OriginLPad == LPad);
996 // If the landing pad has already been mapped, there's nothing more to do.
997 if (OriginLPad == LPad)
1002 // The landingpad instruction returns an aggregate value. Typically, its
1003 // value will be passed to a pair of extract value instructions and the
1004 // results of those extracts will have been promoted to reg values before
1005 // this routine is called.
1006 for (auto *U : LPad->users()) {
1007 const ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
1010 assert(Extract->getNumIndices() == 1 &&
1011 "Unexpected operation: extracting both landing pad values");
1012 unsigned int Idx = *(Extract->idx_begin());
1013 assert((Idx == 0 || Idx == 1) &&
1014 "Unexpected operation: extracting an unknown landing pad element");
1016 ExtractedEHPtrs.push_back(Extract);
1017 } else if (Idx == 1) {
1018 ExtractedSelectors.push_back(Extract);
1023 bool LandingPadMap::isOriginLandingPadBlock(const BasicBlock *BB) const {
1024 return BB->getLandingPadInst() == OriginLPad;
1027 bool LandingPadMap::isLandingPadSpecificInst(const Instruction *Inst) const {
1028 if (Inst == OriginLPad)
1030 for (auto *Extract : ExtractedEHPtrs) {
1031 if (Inst == Extract)
1034 for (auto *Extract : ExtractedSelectors) {
1035 if (Inst == Extract)
1041 void LandingPadMap::remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
1042 Value *SelectorValue) const {
1043 // Remap all landing pad extract instructions to the specified values.
1044 for (auto *Extract : ExtractedEHPtrs)
1045 VMap[Extract] = EHPtrValue;
1046 for (auto *Extract : ExtractedSelectors)
1047 VMap[Extract] = SelectorValue;
1050 CloningDirector::CloningAction WinEHCloningDirectorBase::handleInstruction(
1051 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1052 // If this is one of the boilerplate landing pad instructions, skip it.
1053 // The instruction will have already been remapped in VMap.
1054 if (LPadMap.isLandingPadSpecificInst(Inst))
1055 return CloningDirector::SkipInstruction;
1057 // Nested landing pads will be cloned as stubs, with just the
1058 // landingpad instruction and an unreachable instruction. When
1059 // all landingpads have been outlined, we'll replace this with the
1060 // llvm.eh.actions call and indirect branch created when the
1061 // landing pad was outlined.
1062 if (auto *LPad = dyn_cast<LandingPadInst>(Inst)) {
1063 return handleLandingPad(VMap, LPad, NewBB);
1066 if (auto *Invoke = dyn_cast<InvokeInst>(Inst))
1067 return handleInvoke(VMap, Invoke, NewBB);
1069 if (auto *Resume = dyn_cast<ResumeInst>(Inst))
1070 return handleResume(VMap, Resume, NewBB);
1072 if (auto *Cmp = dyn_cast<CmpInst>(Inst))
1073 return handleCompare(VMap, Cmp, NewBB);
1075 if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>()))
1076 return handleBeginCatch(VMap, Inst, NewBB);
1077 if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
1078 return handleEndCatch(VMap, Inst, NewBB);
1079 if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
1080 return handleTypeIdFor(VMap, Inst, NewBB);
1082 // Continue with the default cloning behavior.
1083 return CloningDirector::CloneInstruction;
1086 CloningDirector::CloningAction WinEHCatchDirector::handleLandingPad(
1087 ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
1088 Instruction *NewInst = LPad->clone();
1089 if (LPad->hasName())
1090 NewInst->setName(LPad->getName());
1091 // Save this correlation for later processing.
1092 NestedLPtoOriginalLP[cast<LandingPadInst>(NewInst)] = LPad;
1093 VMap[LPad] = NewInst;
1094 BasicBlock::InstListType &InstList = NewBB->getInstList();
1095 InstList.push_back(NewInst);
1096 InstList.push_back(new UnreachableInst(NewBB->getContext()));
1097 return CloningDirector::StopCloningBB;
1100 CloningDirector::CloningAction WinEHCatchDirector::handleBeginCatch(
1101 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1102 // The argument to the call is some form of the first element of the
1103 // landingpad aggregate value, but that doesn't matter. It isn't used
1105 // The second argument is an outparameter where the exception object will be
1106 // stored. Typically the exception object is a scalar, but it can be an
1107 // aggregate when catching by value.
1108 // FIXME: Leave something behind to indicate where the exception object lives
1109 // for this handler. Should it be part of llvm.eh.actions?
1110 assert(ExceptionObjectVar == nullptr && "Multiple calls to "
1111 "llvm.eh.begincatch found while "
1112 "outlining catch handler.");
1113 ExceptionObjectVar = Inst->getOperand(1)->stripPointerCasts();
1114 if (isa<ConstantPointerNull>(ExceptionObjectVar))
1115 return CloningDirector::SkipInstruction;
1116 assert(cast<AllocaInst>(ExceptionObjectVar)->isStaticAlloca() &&
1117 "catch parameter is not static alloca");
1118 Materializer.escapeCatchObject(ExceptionObjectVar);
1119 return CloningDirector::SkipInstruction;
1122 CloningDirector::CloningAction
1123 WinEHCatchDirector::handleEndCatch(ValueToValueMapTy &VMap,
1124 const Instruction *Inst, BasicBlock *NewBB) {
1125 auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst);
1126 // It might be interesting to track whether or not we are inside a catch
1127 // function, but that might make the algorithm more brittle than it needs
1130 // The end catch call can occur in one of two places: either in a
1131 // landingpad block that is part of the catch handlers exception mechanism,
1132 // or at the end of the catch block. However, a catch-all handler may call
1133 // end catch from the original landing pad. If the call occurs in a nested
1134 // landing pad block, we must skip it and continue so that the landing pad
1136 auto *ParentBB = IntrinCall->getParent();
1137 if (ParentBB->isLandingPad() && !LPadMap.isOriginLandingPadBlock(ParentBB))
1138 return CloningDirector::SkipInstruction;
1140 // If an end catch occurs anywhere else we want to terminate the handler
1141 // with a return to the code that follows the endcatch call. If the
1142 // next instruction is not an unconditional branch, we need to split the
1143 // block to provide a clear target for the return instruction.
1144 BasicBlock *ContinueBB;
1145 auto Next = std::next(BasicBlock::const_iterator(IntrinCall));
1146 const BranchInst *Branch = dyn_cast<BranchInst>(Next);
1147 if (!Branch || !Branch->isUnconditional()) {
1148 // We're interrupting the cloning process at this location, so the
1149 // const_cast we're doing here will not cause a problem.
1150 ContinueBB = SplitBlock(const_cast<BasicBlock *>(ParentBB),
1151 const_cast<Instruction *>(cast<Instruction>(Next)));
1153 ContinueBB = Branch->getSuccessor(0);
1156 ReturnInst::Create(NewBB->getContext(), BlockAddress::get(ContinueBB), NewBB);
1157 ReturnTargets.push_back(ContinueBB);
1159 // We just added a terminator to the cloned block.
1160 // Tell the caller to stop processing the current basic block so that
1161 // the branch instruction will be skipped.
1162 return CloningDirector::StopCloningBB;
1165 CloningDirector::CloningAction WinEHCatchDirector::handleTypeIdFor(
1166 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1167 auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst);
1168 Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts();
1169 // This causes a replacement that will collapse the landing pad CFG based
1170 // on the filter function we intend to match.
1171 if (Selector == CurrentSelector)
1172 VMap[Inst] = ConstantInt::get(SelectorIDType, 1);
1174 VMap[Inst] = ConstantInt::get(SelectorIDType, 0);
1175 // Tell the caller not to clone this instruction.
1176 return CloningDirector::SkipInstruction;
1179 CloningDirector::CloningAction
1180 WinEHCatchDirector::handleInvoke(ValueToValueMapTy &VMap,
1181 const InvokeInst *Invoke, BasicBlock *NewBB) {
1182 return CloningDirector::CloneInstruction;
1185 CloningDirector::CloningAction
1186 WinEHCatchDirector::handleResume(ValueToValueMapTy &VMap,
1187 const ResumeInst *Resume, BasicBlock *NewBB) {
1188 // Resume instructions shouldn't be reachable from catch handlers.
1189 // We still need to handle it, but it will be pruned.
1190 BasicBlock::InstListType &InstList = NewBB->getInstList();
1191 InstList.push_back(new UnreachableInst(NewBB->getContext()));
1192 return CloningDirector::StopCloningBB;
1195 CloningDirector::CloningAction
1196 WinEHCatchDirector::handleCompare(ValueToValueMapTy &VMap,
1197 const CmpInst *Compare, BasicBlock *NewBB) {
1198 const IntrinsicInst *IntrinCall = nullptr;
1199 if (match(Compare->getOperand(0), m_Intrinsic<Intrinsic::eh_typeid_for>())) {
1200 IntrinCall = dyn_cast<IntrinsicInst>(Compare->getOperand(0));
1201 } else if (match(Compare->getOperand(1), m_Intrinsic<Intrinsic::eh_typeid_for>())) {
1202 IntrinCall = dyn_cast<IntrinsicInst>(Compare->getOperand(1));
1205 Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts();
1206 // This causes a replacement that will collapse the landing pad CFG based
1207 // on the filter function we intend to match.
1208 if (Selector == CurrentSelector->stripPointerCasts()) {
1209 VMap[Compare] = ConstantInt::get(SelectorIDType, 1);
1212 VMap[Compare] = ConstantInt::get(SelectorIDType, 0);
1214 return CloningDirector::SkipInstruction;
1216 return CloningDirector::CloneInstruction;
1219 CloningDirector::CloningAction WinEHCleanupDirector::handleLandingPad(
1220 ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
1221 // The MS runtime will terminate the process if an exception occurs in a
1222 // cleanup handler, so we shouldn't encounter landing pads in the actual
1223 // cleanup code, but they may appear in catch blocks. Depending on where
1224 // we started cloning we may see one, but it will get dropped during dead
1226 Instruction *NewInst = new UnreachableInst(NewBB->getContext());
1227 VMap[LPad] = NewInst;
1228 BasicBlock::InstListType &InstList = NewBB->getInstList();
1229 InstList.push_back(NewInst);
1230 return CloningDirector::StopCloningBB;
1233 CloningDirector::CloningAction WinEHCleanupDirector::handleBeginCatch(
1234 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1235 // Cleanup code may flow into catch blocks or the catch block may be part
1236 // of a branch that will be optimized away. We'll insert a return
1237 // instruction now, but it may be pruned before the cloning process is
1239 ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
1240 return CloningDirector::StopCloningBB;
1243 CloningDirector::CloningAction WinEHCleanupDirector::handleEndCatch(
1244 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1245 // Cleanup handlers nested within catch handlers may begin with a call to
1246 // eh.endcatch. We can just ignore that instruction.
1247 return CloningDirector::SkipInstruction;
1250 CloningDirector::CloningAction WinEHCleanupDirector::handleTypeIdFor(
1251 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1252 // If we encounter a selector comparison while cloning a cleanup handler,
1253 // we want to stop cloning immediately. Anything after the dispatch
1254 // will be outlined into a different handler.
1255 BasicBlock *CatchHandler;
1258 if (isSelectorDispatch(const_cast<BasicBlock *>(Inst->getParent()),
1259 CatchHandler, Selector, NextBB)) {
1260 ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
1261 return CloningDirector::StopCloningBB;
1263 // If eg.typeid.for is called for any other reason, it can be ignored.
1264 VMap[Inst] = ConstantInt::get(SelectorIDType, 0);
1265 return CloningDirector::SkipInstruction;
1268 CloningDirector::CloningAction WinEHCleanupDirector::handleInvoke(
1269 ValueToValueMapTy &VMap, const InvokeInst *Invoke, BasicBlock *NewBB) {
1270 // All invokes in cleanup handlers can be replaced with calls.
1271 SmallVector<Value *, 16> CallArgs(Invoke->op_begin(), Invoke->op_end() - 3);
1272 // Insert a normal call instruction...
1274 CallInst::Create(const_cast<Value *>(Invoke->getCalledValue()), CallArgs,
1275 Invoke->getName(), NewBB);
1276 NewCall->setCallingConv(Invoke->getCallingConv());
1277 NewCall->setAttributes(Invoke->getAttributes());
1278 NewCall->setDebugLoc(Invoke->getDebugLoc());
1279 VMap[Invoke] = NewCall;
1281 // Remap the operands.
1282 llvm::RemapInstruction(NewCall, VMap, RF_None, nullptr, &Materializer);
1284 // Insert an unconditional branch to the normal destination.
1285 BranchInst::Create(Invoke->getNormalDest(), NewBB);
1287 // The unwind destination won't be cloned into the new function, so
1288 // we don't need to clean up its phi nodes.
1290 // We just added a terminator to the cloned block.
1291 // Tell the caller to stop processing the current basic block.
1292 return CloningDirector::CloneSuccessors;
1295 CloningDirector::CloningAction WinEHCleanupDirector::handleResume(
1296 ValueToValueMapTy &VMap, const ResumeInst *Resume, BasicBlock *NewBB) {
1297 ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
1299 // We just added a terminator to the cloned block.
1300 // Tell the caller to stop processing the current basic block so that
1301 // the branch instruction will be skipped.
1302 return CloningDirector::StopCloningBB;
1305 CloningDirector::CloningAction
1306 WinEHCleanupDirector::handleCompare(ValueToValueMapTy &VMap,
1307 const CmpInst *Compare, BasicBlock *NewBB) {
1308 if (match(Compare->getOperand(0), m_Intrinsic<Intrinsic::eh_typeid_for>()) ||
1309 match(Compare->getOperand(1), m_Intrinsic<Intrinsic::eh_typeid_for>())) {
1310 VMap[Compare] = ConstantInt::get(SelectorIDType, 1);
1311 return CloningDirector::SkipInstruction;
1313 return CloningDirector::CloneInstruction;
1317 WinEHFrameVariableMaterializer::WinEHFrameVariableMaterializer(
1318 Function *OutlinedFn, FrameVarInfoMap &FrameVarInfo)
1319 : FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) {
1320 BasicBlock *EntryBB = &OutlinedFn->getEntryBlock();
1321 Builder.SetInsertPoint(EntryBB, EntryBB->getFirstInsertionPt());
1324 Value *WinEHFrameVariableMaterializer::materializeValueFor(Value *V) {
1325 // If we're asked to materialize a value that is an instruction, we
1326 // temporarily create an alloca in the outlined function and add this
1327 // to the FrameVarInfo map. When all the outlining is complete, we'll
1328 // collect these into a structure, spilling non-alloca values in the
1329 // parent frame as necessary, and replace these temporary allocas with
1330 // GEPs referencing the frame allocation block.
1332 // If the value is an alloca, the mapping is direct.
1333 if (auto *AV = dyn_cast<AllocaInst>(V)) {
1334 AllocaInst *NewAlloca = dyn_cast<AllocaInst>(AV->clone());
1335 Builder.Insert(NewAlloca, AV->getName());
1336 FrameVarInfo[AV].push_back(NewAlloca);
1340 // For other types of instructions or arguments, we need an alloca based on
1341 // the value's type and a load of the alloca. The alloca will be replaced
1342 // by a GEP, but the load will stay. In the parent function, the value will
1343 // be spilled to a location in the frame allocation block.
1344 if (isa<Instruction>(V) || isa<Argument>(V)) {
1345 AllocaInst *NewAlloca =
1346 Builder.CreateAlloca(V->getType(), nullptr, "eh.temp.alloca");
1347 FrameVarInfo[V].push_back(NewAlloca);
1348 LoadInst *NewLoad = Builder.CreateLoad(NewAlloca, V->getName() + ".reload");
1352 // Don't materialize other values.
1356 void WinEHFrameVariableMaterializer::escapeCatchObject(Value *V) {
1357 // Catch parameter objects have to live in the parent frame. When we see a use
1358 // of a catch parameter, add a sentinel to the multimap to indicate that it's
1359 // used from another handler. This will prevent us from trying to sink the
1360 // alloca into the handler and ensure that the catch parameter is present in
1361 // the call to llvm.frameescape.
1362 FrameVarInfo[V].push_back(getCatchObjectSentinel());
1365 // This function maps the catch and cleanup handlers that are reachable from the
1366 // specified landing pad. The landing pad sequence will have this basic shape:
1368 // <cleanup handler>
1369 // <selector comparison>
1371 // <cleanup handler>
1372 // <selector comparison>
1374 // <cleanup handler>
1377 // Any of the cleanup slots may be absent. The cleanup slots may be occupied by
1378 // any arbitrary control flow, but all paths through the cleanup code must
1379 // eventually reach the next selector comparison and no path can skip to a
1380 // different selector comparisons, though some paths may terminate abnormally.
1381 // Therefore, we will use a depth first search from the start of any given
1382 // cleanup block and stop searching when we find the next selector comparison.
1384 // If the landingpad instruction does not have a catch clause, we will assume
1385 // that any instructions other than selector comparisons and catch handlers can
1386 // be ignored. In practice, these will only be the boilerplate instructions.
1388 // The catch handlers may also have any control structure, but we are only
1389 // interested in the start of the catch handlers, so we don't need to actually
1390 // follow the flow of the catch handlers. The start of the catch handlers can
1391 // be located from the compare instructions, but they can be skipped in the
1392 // flow by following the contrary branch.
1393 void WinEHPrepare::mapLandingPadBlocks(LandingPadInst *LPad,
1394 LandingPadActions &Actions) {
1395 unsigned int NumClauses = LPad->getNumClauses();
1396 unsigned int HandlersFound = 0;
1397 BasicBlock *BB = LPad->getParent();
1399 DEBUG(dbgs() << "Mapping landing pad: " << BB->getName() << "\n");
1401 if (NumClauses == 0) {
1402 findCleanupHandlers(Actions, BB, nullptr);
1406 VisitedBlockSet VisitedBlocks;
1408 while (HandlersFound != NumClauses) {
1409 BasicBlock *NextBB = nullptr;
1411 // See if the clause we're looking for is a catch-all.
1412 // If so, the catch begins immediately.
1413 Constant *ExpectedSelector = LPad->getClause(HandlersFound)->stripPointerCasts();
1414 if (isa<ConstantPointerNull>(ExpectedSelector)) {
1415 // The catch all must occur last.
1416 assert(HandlersFound == NumClauses - 1);
1418 // There can be additional selector dispatches in the call chain that we
1420 BasicBlock *CatchBlock = nullptr;
1422 while (BB && isSelectorDispatch(BB, CatchBlock, Selector, NextBB)) {
1423 DEBUG(dbgs() << " Found extra catch dispatch in block "
1424 << CatchBlock->getName() << "\n");
1428 // For C++ EH, check if there is any interesting cleanup code before we
1429 // begin the catch. This is important because cleanups cannot rethrow
1430 // exceptions but code called from catches can. For SEH, it isn't
1431 // important if some finally code before a catch-all is executed out of
1432 // line or after recovering from the exception.
1433 if (Personality == EHPersonality::MSVC_CXX)
1434 findCleanupHandlers(Actions, BB, BB);
1436 // Add the catch handler to the action list.
1437 CatchHandler *Action = nullptr;
1438 if (CatchHandlerMap.count(BB) && CatchHandlerMap[BB] != nullptr) {
1439 // If the CatchHandlerMap already has an entry for this BB, re-use it.
1440 Action = CatchHandlerMap[BB];
1441 assert(Action->getSelector() == ExpectedSelector);
1443 // Since this is a catch-all handler, the selector won't actually appear
1444 // in the code anywhere. ExpectedSelector here is the constant null ptr
1445 // that we got from the landing pad instruction.
1446 Action = new CatchHandler(BB, ExpectedSelector, nullptr);
1447 CatchHandlerMap[BB] = Action;
1449 Actions.insertCatchHandler(Action);
1450 DEBUG(dbgs() << " Catch all handler at block " << BB->getName() << "\n");
1453 // Once we reach a catch-all, don't expect to hit a resume instruction.
1458 CatchHandler *CatchAction = findCatchHandler(BB, NextBB, VisitedBlocks);
1459 assert(CatchAction);
1461 // See if there is any interesting code executed before the dispatch.
1462 findCleanupHandlers(Actions, BB, CatchAction->getStartBlock());
1464 // When the source program contains multiple nested try blocks the catch
1465 // handlers can get strung together in such a way that we can encounter
1466 // a dispatch for a selector that we've already had a handler for.
1467 if (CatchAction->getSelector()->stripPointerCasts() == ExpectedSelector) {
1470 // Add the catch handler to the action list.
1471 DEBUG(dbgs() << " Found catch dispatch in block "
1472 << CatchAction->getStartBlock()->getName() << "\n");
1473 Actions.insertCatchHandler(CatchAction);
1475 // Under some circumstances optimized IR will flow unconditionally into a
1476 // handler block without checking the selector. This can only happen if
1477 // the landing pad has a catch-all handler and the handler for the
1478 // preceeding catch clause is identical to the catch-call handler
1479 // (typically an empty catch). In this case, the handler must be shared
1480 // by all remaining clauses.
1481 if (isa<ConstantPointerNull>(
1482 CatchAction->getSelector()->stripPointerCasts())) {
1483 DEBUG(dbgs() << " Applying early catch-all handler in block "
1484 << CatchAction->getStartBlock()->getName()
1485 << " to all remaining clauses.\n");
1486 Actions.insertCatchHandler(CatchAction);
1490 DEBUG(dbgs() << " Found extra catch dispatch in block "
1491 << CatchAction->getStartBlock()->getName() << "\n");
1494 // Move on to the block after the catch handler.
1498 // If we didn't wind up in a catch-all, see if there is any interesting code
1499 // executed before the resume.
1500 findCleanupHandlers(Actions, BB, BB);
1502 // It's possible that some optimization moved code into a landingpad that
1504 // previously being used for cleanup. If that happens, we need to execute
1506 // extra code from a cleanup handler.
1507 if (Actions.includesCleanup() && !LPad->isCleanup())
1508 LPad->setCleanup(true);
1511 // This function searches starting with the input block for the next
1512 // block that terminates with a branch whose condition is based on a selector
1513 // comparison. This may be the input block. See the mapLandingPadBlocks
1514 // comments for a discussion of control flow assumptions.
1516 CatchHandler *WinEHPrepare::findCatchHandler(BasicBlock *BB,
1517 BasicBlock *&NextBB,
1518 VisitedBlockSet &VisitedBlocks) {
1519 // See if we've already found a catch handler use it.
1520 // Call count() first to avoid creating a null entry for blocks
1521 // we haven't seen before.
1522 if (CatchHandlerMap.count(BB) && CatchHandlerMap[BB] != nullptr) {
1523 CatchHandler *Action = cast<CatchHandler>(CatchHandlerMap[BB]);
1524 NextBB = Action->getNextBB();
1528 // VisitedBlocks applies only to the current search. We still
1529 // need to consider blocks that we've visited while mapping other
1531 VisitedBlocks.insert(BB);
1533 BasicBlock *CatchBlock = nullptr;
1534 Constant *Selector = nullptr;
1536 // If this is the first time we've visited this block from any landing pad
1537 // look to see if it is a selector dispatch block.
1538 if (!CatchHandlerMap.count(BB)) {
1539 if (isSelectorDispatch(BB, CatchBlock, Selector, NextBB)) {
1540 CatchHandler *Action = new CatchHandler(BB, Selector, NextBB);
1541 CatchHandlerMap[BB] = Action;
1544 // If we encounter a block containing an llvm.eh.begincatch before we
1545 // find a selector dispatch block, the handler is assumed to be
1546 // reached unconditionally. This happens for catch-all blocks, but
1547 // it can also happen for other catch handlers that have been combined
1548 // with the catch-all handler during optimization.
1549 if (isCatchBlock(BB)) {
1550 PointerType *Int8PtrTy = Type::getInt8PtrTy(BB->getContext());
1551 Constant *NullSelector = ConstantPointerNull::get(Int8PtrTy);
1552 CatchHandler *Action = new CatchHandler(BB, NullSelector, nullptr);
1553 CatchHandlerMap[BB] = Action;
1558 // Visit each successor, looking for the dispatch.
1559 // FIXME: We expect to find the dispatch quickly, so this will probably
1560 // work better as a breadth first search.
1561 for (BasicBlock *Succ : successors(BB)) {
1562 if (VisitedBlocks.count(Succ))
1565 CatchHandler *Action = findCatchHandler(Succ, NextBB, VisitedBlocks);
1572 // These are helper functions to combine repeated code from findCleanupHandlers.
1573 static void createCleanupHandler(LandingPadActions &Actions,
1574 CleanupHandlerMapTy &CleanupHandlerMap,
1576 CleanupHandler *Action = new CleanupHandler(BB);
1577 CleanupHandlerMap[BB] = Action;
1578 Actions.insertCleanupHandler(Action);
1579 DEBUG(dbgs() << " Found cleanup code in block "
1580 << Action->getStartBlock()->getName() << "\n");
1583 static bool isFrameAddressCall(Value *V) {
1584 return match(V, m_Intrinsic<Intrinsic::frameaddress>(m_SpecificInt(0)));
1587 static CallSite matchOutlinedFinallyCall(BasicBlock *BB,
1588 Instruction *MaybeCall) {
1589 // Look for finally blocks that Clang has already outlined for us.
1590 // %fp = call i8* @llvm.frameaddress(i32 0)
1591 // call void @"fin$parent"(iN 1, i8* %fp)
1592 if (isFrameAddressCall(MaybeCall) && MaybeCall != BB->getTerminator())
1593 MaybeCall = MaybeCall->getNextNode();
1594 CallSite FinallyCall(MaybeCall);
1595 if (!FinallyCall || FinallyCall.arg_size() != 2)
1597 if (!match(FinallyCall.getArgument(0), m_SpecificInt(1)))
1599 if (!isFrameAddressCall(FinallyCall.getArgument(1)))
1604 static BasicBlock *followSingleUnconditionalBranches(BasicBlock *BB) {
1605 // Skip single ubr blocks.
1606 while (BB->getFirstNonPHIOrDbg() == BB->getTerminator()) {
1607 auto *Br = dyn_cast<BranchInst>(BB->getTerminator());
1608 if (Br && Br->isUnconditional())
1609 BB = Br->getSuccessor(0);
1616 // This function searches starting with the input block for the next block that
1617 // contains code that is not part of a catch handler and would not be eliminated
1618 // during handler outlining.
1620 void WinEHPrepare::findCleanupHandlers(LandingPadActions &Actions,
1621 BasicBlock *StartBB, BasicBlock *EndBB) {
1622 // Here we will skip over the following:
1624 // landing pad prolog:
1626 // Unconditional branches
1628 // Selector dispatch
1632 // Anything else marks the start of an interesting block
1634 BasicBlock *BB = StartBB;
1635 // Anything other than an unconditional branch will kick us out of this loop
1636 // one way or another.
1638 BB = followSingleUnconditionalBranches(BB);
1639 // If we've already scanned this block, don't scan it again. If it is
1640 // a cleanup block, there will be an action in the CleanupHandlerMap.
1641 // If we've scanned it and it is not a cleanup block, there will be a
1642 // nullptr in the CleanupHandlerMap. If we have not scanned it, there will
1643 // be no entry in the CleanupHandlerMap. We must call count() first to
1644 // avoid creating a null entry for blocks we haven't scanned.
1645 if (CleanupHandlerMap.count(BB)) {
1646 if (auto *Action = CleanupHandlerMap[BB]) {
1647 Actions.insertCleanupHandler(Action);
1648 DEBUG(dbgs() << " Found cleanup code in block "
1649 << Action->getStartBlock()->getName() << "\n");
1650 // FIXME: This cleanup might chain into another, and we need to discover
1654 // Here we handle the case where the cleanup handler map contains a
1655 // value for this block but the value is a nullptr. This means that
1656 // we have previously analyzed the block and determined that it did
1657 // not contain any cleanup code. Based on the earlier analysis, we
1658 // know the the block must end in either an unconditional branch, a
1659 // resume or a conditional branch that is predicated on a comparison
1660 // with a selector. Either the resume or the selector dispatch
1661 // would terminate the search for cleanup code, so the unconditional
1662 // branch is the only case for which we might need to continue
1664 BasicBlock *SuccBB = followSingleUnconditionalBranches(BB);
1665 if (SuccBB == BB || SuccBB == EndBB)
1672 // Create an entry in the cleanup handler map for this block. Initially
1673 // we create an entry that says this isn't a cleanup block. If we find
1674 // cleanup code, the caller will replace this entry.
1675 CleanupHandlerMap[BB] = nullptr;
1677 TerminatorInst *Terminator = BB->getTerminator();
1679 // Landing pad blocks have extra instructions we need to accept.
1680 LandingPadMap *LPadMap = nullptr;
1681 if (BB->isLandingPad()) {
1682 LandingPadInst *LPad = BB->getLandingPadInst();
1683 LPadMap = &LPadMaps[LPad];
1684 if (!LPadMap->isInitialized())
1685 LPadMap->mapLandingPad(LPad);
1688 // Look for the bare resume pattern:
1689 // %lpad.val1 = insertvalue { i8*, i32 } undef, i8* %exn, 0
1690 // %lpad.val2 = insertvalue { i8*, i32 } %lpad.val1, i32 %sel, 1
1691 // resume { i8*, i32 } %lpad.val2
1692 if (auto *Resume = dyn_cast<ResumeInst>(Terminator)) {
1693 InsertValueInst *Insert1 = nullptr;
1694 InsertValueInst *Insert2 = nullptr;
1695 Value *ResumeVal = Resume->getOperand(0);
1696 // If the resume value isn't a phi or landingpad value, it should be a
1697 // series of insertions. Identify them so we can avoid them when scanning
1699 if (!isa<PHINode>(ResumeVal) && !isa<LandingPadInst>(ResumeVal)) {
1700 Insert2 = dyn_cast<InsertValueInst>(ResumeVal);
1702 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
1703 Insert1 = dyn_cast<InsertValueInst>(Insert2->getAggregateOperand());
1705 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
1707 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
1709 Instruction *Inst = II;
1710 if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
1712 if (Inst == Insert1 || Inst == Insert2 || Inst == Resume)
1714 if (!Inst->hasOneUse() ||
1715 (Inst->user_back() != Insert1 && Inst->user_back() != Insert2)) {
1716 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
1722 BranchInst *Branch = dyn_cast<BranchInst>(Terminator);
1723 if (Branch && Branch->isConditional()) {
1724 // Look for the selector dispatch.
1725 // %2 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIf to i8*))
1726 // %matches = icmp eq i32 %sel, %2
1727 // br i1 %matches, label %catch14, label %eh.resume
1728 CmpInst *Compare = dyn_cast<CmpInst>(Branch->getCondition());
1729 if (!Compare || !Compare->isEquality())
1730 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
1731 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
1733 Instruction *Inst = II;
1734 if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
1736 if (Inst == Compare || Inst == Branch)
1738 if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
1740 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
1742 // The selector dispatch block should always terminate our search.
1743 assert(BB == EndBB);
1747 if (isAsynchronousEHPersonality(Personality)) {
1748 // If this is a landingpad block, split the block at the first non-landing
1750 Instruction *MaybeCall = BB->getFirstNonPHIOrDbg();
1752 while (MaybeCall != BB->getTerminator() &&
1753 LPadMap->isLandingPadSpecificInst(MaybeCall))
1754 MaybeCall = MaybeCall->getNextNode();
1757 // Look for outlined finally calls.
1758 if (CallSite FinallyCall = matchOutlinedFinallyCall(BB, MaybeCall)) {
1759 Function *Fin = FinallyCall.getCalledFunction();
1760 assert(Fin && "outlined finally call should be direct");
1761 auto *Action = new CleanupHandler(BB);
1762 Action->setHandlerBlockOrFunc(Fin);
1763 Actions.insertCleanupHandler(Action);
1764 CleanupHandlerMap[BB] = Action;
1765 DEBUG(dbgs() << " Found frontend-outlined finally call to "
1766 << Fin->getName() << " in block "
1767 << Action->getStartBlock()->getName() << "\n");
1769 // Split the block if there were more interesting instructions and look
1770 // for finally calls in the normal successor block.
1771 BasicBlock *SuccBB = BB;
1772 if (FinallyCall.getInstruction() != BB->getTerminator() &&
1773 FinallyCall.getInstruction()->getNextNode() != BB->getTerminator()) {
1774 SuccBB = BB->splitBasicBlock(FinallyCall.getInstruction()->getNextNode());
1776 if (FinallyCall.isInvoke()) {
1777 SuccBB = cast<InvokeInst>(FinallyCall.getInstruction())->getNormalDest();
1779 SuccBB = BB->getUniqueSuccessor();
1780 assert(SuccBB && "splitOutlinedFinallyCalls didn't insert a branch");
1790 // Anything else is either a catch block or interesting cleanup code.
1791 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
1793 Instruction *Inst = II;
1794 if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
1796 // Unconditional branches fall through to this loop.
1799 // If this is a catch block, there is no cleanup code to be found.
1800 if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>()))
1802 // If this a nested landing pad, it may contain an endcatch call.
1803 if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
1805 // Anything else makes this interesting cleanup code.
1806 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
1809 // Only unconditional branches in empty blocks should get this far.
1810 assert(Branch && Branch->isUnconditional());
1813 BB = Branch->getSuccessor(0);
1817 // This is a public function, declared in WinEHFuncInfo.h and is also
1818 // referenced by WinEHNumbering in FunctionLoweringInfo.cpp.
1819 void llvm::parseEHActions(const IntrinsicInst *II,
1820 SmallVectorImpl<ActionHandler *> &Actions) {
1821 for (unsigned I = 0, E = II->getNumArgOperands(); I != E;) {
1822 uint64_t ActionKind =
1823 cast<ConstantInt>(II->getArgOperand(I))->getZExtValue();
1824 if (ActionKind == /*catch=*/1) {
1825 auto *Selector = cast<Constant>(II->getArgOperand(I + 1));
1826 ConstantInt *EHObjIndex = cast<ConstantInt>(II->getArgOperand(I + 2));
1827 int64_t EHObjIndexVal = EHObjIndex->getSExtValue();
1828 Constant *Handler = cast<Constant>(II->getArgOperand(I + 3));
1830 auto *CH = new CatchHandler(/*BB=*/nullptr, Selector, /*NextBB=*/nullptr);
1831 CH->setHandlerBlockOrFunc(Handler);
1832 CH->setExceptionVarIndex(EHObjIndexVal);
1833 Actions.push_back(CH);
1834 } else if (ActionKind == 0) {
1835 Constant *Handler = cast<Constant>(II->getArgOperand(I + 1));
1837 auto *CH = new CleanupHandler(/*BB=*/nullptr);
1838 CH->setHandlerBlockOrFunc(Handler);
1839 Actions.push_back(CH);
1841 llvm_unreachable("Expected either a catch or cleanup handler!");
1844 std::reverse(Actions.begin(), Actions.end());