1 //===-- WinEHPrepare - Prepare exception handling for code generation ---===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This pass lowers LLVM IR exception handling into something closer to what the
11 // backend wants for functions using a personality function from a runtime
12 // provided by MSVC. Functions with other personality functions are left alone
13 // and may be prepared by other passes. In particular, all supported MSVC
14 // personality functions require cleanup code to be outlined, and the C++
15 // personality requires catch handler code to be outlined.
17 //===----------------------------------------------------------------------===//
19 #include "llvm/CodeGen/Passes.h"
20 #include "llvm/ADT/MapVector.h"
21 #include "llvm/ADT/STLExtras.h"
22 #include "llvm/ADT/SmallSet.h"
23 #include "llvm/ADT/SetVector.h"
24 #include "llvm/ADT/Triple.h"
25 #include "llvm/ADT/TinyPtrVector.h"
26 #include "llvm/Analysis/LibCallSemantics.h"
27 #include "llvm/CodeGen/WinEHFuncInfo.h"
28 #include "llvm/IR/Dominators.h"
29 #include "llvm/IR/Function.h"
30 #include "llvm/IR/IRBuilder.h"
31 #include "llvm/IR/Instructions.h"
32 #include "llvm/IR/IntrinsicInst.h"
33 #include "llvm/IR/Module.h"
34 #include "llvm/IR/PatternMatch.h"
35 #include "llvm/Pass.h"
36 #include "llvm/Support/Debug.h"
37 #include "llvm/Support/raw_ostream.h"
38 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
39 #include "llvm/Transforms/Utils/Cloning.h"
40 #include "llvm/Transforms/Utils/Local.h"
41 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
45 using namespace llvm::PatternMatch;
47 #define DEBUG_TYPE "winehprepare"
51 // This map is used to model frame variable usage during outlining, to
52 // construct a structure type to hold the frame variables in a frame
53 // allocation block, and to remap the frame variable allocas (including
54 // spill locations as needed) to GEPs that get the variable from the
55 // frame allocation structure.
56 typedef MapVector<Value *, TinyPtrVector<AllocaInst *>> FrameVarInfoMap;
58 // TinyPtrVector cannot hold nullptr, so we need our own sentinel that isn't
60 AllocaInst *getCatchObjectSentinel() {
61 return static_cast<AllocaInst *>(nullptr) + 1;
64 typedef SmallSet<BasicBlock *, 4> VisitedBlockSet;
66 class LandingPadActions;
69 typedef DenseMap<const BasicBlock *, CatchHandler *> CatchHandlerMapTy;
70 typedef DenseMap<const BasicBlock *, CleanupHandler *> CleanupHandlerMapTy;
72 class WinEHPrepare : public FunctionPass {
74 static char ID; // Pass identification, replacement for typeid.
75 WinEHPrepare(const TargetMachine *TM = nullptr)
78 TheTriple = Triple(TM->getTargetTriple());
81 bool runOnFunction(Function &Fn) override;
83 bool doFinalization(Module &M) override;
85 void getAnalysisUsage(AnalysisUsage &AU) const override;
87 const char *getPassName() const override {
88 return "Windows exception handling preparation";
92 bool prepareExceptionHandlers(Function &F,
93 SmallVectorImpl<LandingPadInst *> &LPads);
94 void promoteLandingPadValues(LandingPadInst *LPad);
95 void demoteValuesLiveAcrossHandlers(Function &F,
96 SmallVectorImpl<LandingPadInst *> &LPads);
97 void findSEHEHReturnPoints(Function &F,
98 SetVector<BasicBlock *> &EHReturnBlocks);
99 void findCXXEHReturnPoints(Function &F,
100 SetVector<BasicBlock *> &EHReturnBlocks);
101 void completeNestedLandingPad(Function *ParentFn,
102 LandingPadInst *OutlinedLPad,
103 const LandingPadInst *OriginalLPad,
104 FrameVarInfoMap &VarInfo);
105 Function *createHandlerFunc(Type *RetTy, const Twine &Name, Module *M,
107 bool outlineHandler(ActionHandler *Action, Function *SrcFn,
108 LandingPadInst *LPad, BasicBlock *StartBB,
109 FrameVarInfoMap &VarInfo);
110 void addStubInvokeToHandlerIfNeeded(Function *Handler, Value *PersonalityFn);
112 void mapLandingPadBlocks(LandingPadInst *LPad, LandingPadActions &Actions);
113 CatchHandler *findCatchHandler(BasicBlock *BB, BasicBlock *&NextBB,
114 VisitedBlockSet &VisitedBlocks);
115 void findCleanupHandlers(LandingPadActions &Actions, BasicBlock *StartBB,
118 void processSEHCatchHandler(CatchHandler *Handler, BasicBlock *StartBB);
122 // All fields are reset by runOnFunction.
123 DominatorTree *DT = nullptr;
124 EHPersonality Personality = EHPersonality::Unknown;
125 CatchHandlerMapTy CatchHandlerMap;
126 CleanupHandlerMapTy CleanupHandlerMap;
127 DenseMap<const LandingPadInst *, LandingPadMap> LPadMaps;
129 // This maps landing pad instructions found in outlined handlers to
130 // the landing pad instruction in the parent function from which they
131 // were cloned. The cloned/nested landing pad is used as the key
132 // because the landing pad may be cloned into multiple handlers.
133 // This map will be used to add the llvm.eh.actions call to the nested
134 // landing pads after all handlers have been outlined.
135 DenseMap<LandingPadInst *, const LandingPadInst *> NestedLPtoOriginalLP;
137 // This maps blocks in the parent function which are destinations of
138 // catch handlers to cloned blocks in (other) outlined handlers. This
139 // handles the case where a nested landing pads has a catch handler that
140 // returns to a handler function rather than the parent function.
141 // The original block is used as the key here because there should only
142 // ever be one handler function from which the cloned block is not pruned.
143 // The original block will be pruned from the parent function after all
144 // handlers have been outlined. This map will be used to adjust the
145 // return instructions of handlers which return to the block that was
146 // outlined into a handler. This is done after all handlers have been
147 // outlined but before the outlined code is pruned from the parent function.
148 DenseMap<const BasicBlock *, BasicBlock *> LPadTargetBlocks;
150 // Map from outlined handler to call to llvm.frameaddress(1). Only used for
152 DenseMap<Function *, Value *> HandlerToParentFP;
154 AllocaInst *SEHExceptionCodeSlot = nullptr;
157 class WinEHFrameVariableMaterializer : public ValueMaterializer {
159 WinEHFrameVariableMaterializer(Function *OutlinedFn, Value *ParentFP,
160 FrameVarInfoMap &FrameVarInfo);
161 ~WinEHFrameVariableMaterializer() override {}
163 Value *materializeValueFor(Value *V) override;
165 void escapeCatchObject(Value *V);
168 FrameVarInfoMap &FrameVarInfo;
172 class LandingPadMap {
174 LandingPadMap() : OriginLPad(nullptr) {}
175 void mapLandingPad(const LandingPadInst *LPad);
177 bool isInitialized() { return OriginLPad != nullptr; }
179 bool isOriginLandingPadBlock(const BasicBlock *BB) const;
180 bool isLandingPadSpecificInst(const Instruction *Inst) const;
182 void remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
183 Value *SelectorValue) const;
186 const LandingPadInst *OriginLPad;
187 // We will normally only see one of each of these instructions, but
188 // if more than one occurs for some reason we can handle that.
189 TinyPtrVector<const ExtractValueInst *> ExtractedEHPtrs;
190 TinyPtrVector<const ExtractValueInst *> ExtractedSelectors;
193 class WinEHCloningDirectorBase : public CloningDirector {
195 WinEHCloningDirectorBase(Function *HandlerFn, Value *ParentFP,
196 FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
197 : Materializer(HandlerFn, ParentFP, VarInfo),
198 SelectorIDType(Type::getInt32Ty(HandlerFn->getContext())),
199 Int8PtrType(Type::getInt8PtrTy(HandlerFn->getContext())),
200 LPadMap(LPadMap), ParentFP(ParentFP) {}
202 CloningAction handleInstruction(ValueToValueMapTy &VMap,
203 const Instruction *Inst,
204 BasicBlock *NewBB) override;
206 virtual CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
207 const Instruction *Inst,
208 BasicBlock *NewBB) = 0;
209 virtual CloningAction handleEndCatch(ValueToValueMapTy &VMap,
210 const Instruction *Inst,
211 BasicBlock *NewBB) = 0;
212 virtual CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
213 const Instruction *Inst,
214 BasicBlock *NewBB) = 0;
215 virtual CloningAction handleInvoke(ValueToValueMapTy &VMap,
216 const InvokeInst *Invoke,
217 BasicBlock *NewBB) = 0;
218 virtual CloningAction handleResume(ValueToValueMapTy &VMap,
219 const ResumeInst *Resume,
220 BasicBlock *NewBB) = 0;
221 virtual CloningAction handleCompare(ValueToValueMapTy &VMap,
222 const CmpInst *Compare,
223 BasicBlock *NewBB) = 0;
224 virtual CloningAction handleLandingPad(ValueToValueMapTy &VMap,
225 const LandingPadInst *LPad,
226 BasicBlock *NewBB) = 0;
228 ValueMaterializer *getValueMaterializer() override { return &Materializer; }
231 WinEHFrameVariableMaterializer Materializer;
232 Type *SelectorIDType;
234 LandingPadMap &LPadMap;
236 /// The value representing the parent frame pointer.
240 class WinEHCatchDirector : public WinEHCloningDirectorBase {
243 Function *CatchFn, Value *ParentFP, Value *Selector,
244 FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap,
245 DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPads)
246 : WinEHCloningDirectorBase(CatchFn, ParentFP, VarInfo, LPadMap),
247 CurrentSelector(Selector->stripPointerCasts()),
248 ExceptionObjectVar(nullptr), NestedLPtoOriginalLP(NestedLPads) {}
250 CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
251 const Instruction *Inst,
252 BasicBlock *NewBB) override;
253 CloningAction handleEndCatch(ValueToValueMapTy &VMap, const Instruction *Inst,
254 BasicBlock *NewBB) override;
255 CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
256 const Instruction *Inst,
257 BasicBlock *NewBB) override;
258 CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
259 BasicBlock *NewBB) override;
260 CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
261 BasicBlock *NewBB) override;
262 CloningAction handleCompare(ValueToValueMapTy &VMap, const CmpInst *Compare,
263 BasicBlock *NewBB) override;
264 CloningAction handleLandingPad(ValueToValueMapTy &VMap,
265 const LandingPadInst *LPad,
266 BasicBlock *NewBB) override;
268 Value *getExceptionVar() { return ExceptionObjectVar; }
269 TinyPtrVector<BasicBlock *> &getReturnTargets() { return ReturnTargets; }
272 Value *CurrentSelector;
274 Value *ExceptionObjectVar;
275 TinyPtrVector<BasicBlock *> ReturnTargets;
277 // This will be a reference to the field of the same name in the WinEHPrepare
278 // object which instantiates this WinEHCatchDirector object.
279 DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPtoOriginalLP;
282 class WinEHCleanupDirector : public WinEHCloningDirectorBase {
284 WinEHCleanupDirector(Function *CleanupFn, Value *ParentFP,
285 FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
286 : WinEHCloningDirectorBase(CleanupFn, ParentFP, VarInfo,
289 CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
290 const Instruction *Inst,
291 BasicBlock *NewBB) override;
292 CloningAction handleEndCatch(ValueToValueMapTy &VMap, const Instruction *Inst,
293 BasicBlock *NewBB) override;
294 CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
295 const Instruction *Inst,
296 BasicBlock *NewBB) override;
297 CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
298 BasicBlock *NewBB) override;
299 CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
300 BasicBlock *NewBB) override;
301 CloningAction handleCompare(ValueToValueMapTy &VMap, const CmpInst *Compare,
302 BasicBlock *NewBB) override;
303 CloningAction handleLandingPad(ValueToValueMapTy &VMap,
304 const LandingPadInst *LPad,
305 BasicBlock *NewBB) override;
308 class LandingPadActions {
310 LandingPadActions() : HasCleanupHandlers(false) {}
312 void insertCatchHandler(CatchHandler *Action) { Actions.push_back(Action); }
313 void insertCleanupHandler(CleanupHandler *Action) {
314 Actions.push_back(Action);
315 HasCleanupHandlers = true;
318 bool includesCleanup() const { return HasCleanupHandlers; }
320 SmallVectorImpl<ActionHandler *> &actions() { return Actions; }
321 SmallVectorImpl<ActionHandler *>::iterator begin() { return Actions.begin(); }
322 SmallVectorImpl<ActionHandler *>::iterator end() { return Actions.end(); }
325 // Note that this class does not own the ActionHandler objects in this vector.
326 // The ActionHandlers are owned by the CatchHandlerMap and CleanupHandlerMap
327 // in the WinEHPrepare class.
328 SmallVector<ActionHandler *, 4> Actions;
329 bool HasCleanupHandlers;
332 } // end anonymous namespace
334 char WinEHPrepare::ID = 0;
335 INITIALIZE_TM_PASS(WinEHPrepare, "winehprepare", "Prepare Windows exceptions",
338 FunctionPass *llvm::createWinEHPass(const TargetMachine *TM) {
339 return new WinEHPrepare(TM);
342 bool WinEHPrepare::runOnFunction(Function &Fn) {
343 // No need to prepare outlined handlers.
344 if (Fn.hasFnAttribute("wineh-parent"))
347 SmallVector<LandingPadInst *, 4> LPads;
348 SmallVector<ResumeInst *, 4> Resumes;
349 for (BasicBlock &BB : Fn) {
350 if (auto *LP = BB.getLandingPadInst())
352 if (auto *Resume = dyn_cast<ResumeInst>(BB.getTerminator()))
353 Resumes.push_back(Resume);
356 // No need to prepare functions that lack landing pads.
360 // Classify the personality to see what kind of preparation we need.
361 Personality = classifyEHPersonality(LPads.back()->getPersonalityFn());
363 // Do nothing if this is not an MSVC personality.
364 if (!isMSVCEHPersonality(Personality))
367 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
369 // If there were any landing pads, prepareExceptionHandlers will make changes.
370 prepareExceptionHandlers(Fn, LPads);
374 bool WinEHPrepare::doFinalization(Module &M) { return false; }
376 void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {
377 AU.addRequired<DominatorTreeWrapperPass>();
380 static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler,
381 Constant *&Selector, BasicBlock *&NextBB);
383 // Finds blocks reachable from the starting set Worklist. Does not follow unwind
384 // edges or blocks listed in StopPoints.
385 static void findReachableBlocks(SmallPtrSetImpl<BasicBlock *> &ReachableBBs,
386 SetVector<BasicBlock *> &Worklist,
387 const SetVector<BasicBlock *> *StopPoints) {
388 while (!Worklist.empty()) {
389 BasicBlock *BB = Worklist.pop_back_val();
391 // Don't cross blocks that we should stop at.
392 if (StopPoints && StopPoints->count(BB))
395 if (!ReachableBBs.insert(BB).second)
396 continue; // Already visited.
398 // Don't follow unwind edges of invokes.
399 if (auto *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
400 Worklist.insert(II->getNormalDest());
404 // Otherwise, follow all successors.
405 Worklist.insert(succ_begin(BB), succ_end(BB));
409 // Attempt to find an instruction where a block can be split before
410 // a call to llvm.eh.begincatch and its operands. If the block
411 // begins with the begincatch call or one of its adjacent operands
412 // the block will not be split.
413 static Instruction *findBeginCatchSplitPoint(BasicBlock *BB,
415 // If the begincatch call is already the first instruction in the block,
417 Instruction *FirstNonPHI = BB->getFirstNonPHI();
418 if (II == FirstNonPHI)
421 // If either operand is in the same basic block as the instruction and
422 // isn't used by another instruction before the begincatch call, include it
423 // in the split block.
424 auto *Op0 = dyn_cast<Instruction>(II->getOperand(0));
425 auto *Op1 = dyn_cast<Instruction>(II->getOperand(1));
427 Instruction *I = II->getPrevNode();
428 Instruction *LastI = II;
430 while (I == Op0 || I == Op1) {
431 // If the block begins with one of the operands and there are no other
432 // instructions between the operand and the begincatch call, don't split.
433 if (I == FirstNonPHI)
437 I = I->getPrevNode();
440 // If there is at least one instruction in the block before the begincatch
441 // call and its operands, split the block at either the begincatch or
446 /// Find all points where exceptional control rejoins normal control flow via
447 /// llvm.eh.endcatch. Add them to the normal bb reachability worklist.
448 void WinEHPrepare::findCXXEHReturnPoints(
449 Function &F, SetVector<BasicBlock *> &EHReturnBlocks) {
450 for (auto BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) {
451 BasicBlock *BB = BBI;
452 for (Instruction &I : *BB) {
453 if (match(&I, m_Intrinsic<Intrinsic::eh_begincatch>())) {
454 Instruction *SplitPt =
455 findBeginCatchSplitPoint(BB, cast<IntrinsicInst>(&I));
457 // Split the block before the llvm.eh.begincatch call to allow
458 // cleanup and catch code to be distinguished later.
459 // Do not update BBI because we still need to process the
460 // portion of the block that we are splitting off.
461 SplitBlock(BB, SplitPt, DT);
465 if (match(&I, m_Intrinsic<Intrinsic::eh_endcatch>())) {
466 // Split the block after the call to llvm.eh.endcatch if there is
467 // anything other than an unconditional branch, or if the successor
468 // starts with a phi.
469 auto *Br = dyn_cast<BranchInst>(I.getNextNode());
470 if (!Br || !Br->isUnconditional() ||
471 isa<PHINode>(Br->getSuccessor(0)->begin())) {
472 DEBUG(dbgs() << "splitting block " << BB->getName()
473 << " with llvm.eh.endcatch\n");
474 BBI = SplitBlock(BB, I.getNextNode(), DT);
476 // The next BB is normal control flow.
477 EHReturnBlocks.insert(BB->getTerminator()->getSuccessor(0));
484 static bool isCatchAllLandingPad(const BasicBlock *BB) {
485 const LandingPadInst *LP = BB->getLandingPadInst();
488 unsigned N = LP->getNumClauses();
489 return (N > 0 && LP->isCatch(N - 1) &&
490 isa<ConstantPointerNull>(LP->getClause(N - 1)));
493 /// Find all points where exceptions control rejoins normal control flow via
494 /// selector dispatch.
495 void WinEHPrepare::findSEHEHReturnPoints(
496 Function &F, SetVector<BasicBlock *> &EHReturnBlocks) {
497 for (auto BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) {
498 BasicBlock *BB = BBI;
499 // If the landingpad is a catch-all, treat the whole lpad as if it is
500 // reachable from normal control flow.
501 // FIXME: This is imprecise. We need a better way of identifying where a
502 // catch-all starts and cleanups stop. As far as LLVM is concerned, there
504 if (isCatchAllLandingPad(BB)) {
505 EHReturnBlocks.insert(BB);
509 BasicBlock *CatchHandler;
512 if (isSelectorDispatch(BB, CatchHandler, Selector, NextBB)) {
513 // Split the edge if there is a phi node. Returning from EH to a phi node
514 // is just as impossible as having a phi after an indirectbr.
515 if (isa<PHINode>(CatchHandler->begin())) {
516 DEBUG(dbgs() << "splitting EH return edge from " << BB->getName()
517 << " to " << CatchHandler->getName() << '\n');
518 BBI = CatchHandler = SplitCriticalEdge(
519 BB, std::find(succ_begin(BB), succ_end(BB), CatchHandler));
521 EHReturnBlocks.insert(CatchHandler);
526 /// Ensure that all values live into and out of exception handlers are stored
528 /// FIXME: This falls down when values are defined in one handler and live into
529 /// another handler. For example, a cleanup defines a value used only by a
531 void WinEHPrepare::demoteValuesLiveAcrossHandlers(
532 Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
533 DEBUG(dbgs() << "Demoting values live across exception handlers in function "
534 << F.getName() << '\n');
536 // Build a set of all non-exceptional blocks and exceptional blocks.
537 // - Non-exceptional blocks are blocks reachable from the entry block while
538 // not following invoke unwind edges.
539 // - Exceptional blocks are blocks reachable from landingpads. Analysis does
540 // not follow llvm.eh.endcatch blocks, which mark a transition from
541 // exceptional to normal control.
542 SmallPtrSet<BasicBlock *, 4> NormalBlocks;
543 SmallPtrSet<BasicBlock *, 4> EHBlocks;
544 SetVector<BasicBlock *> EHReturnBlocks;
545 SetVector<BasicBlock *> Worklist;
547 if (Personality == EHPersonality::MSVC_CXX)
548 findCXXEHReturnPoints(F, EHReturnBlocks);
550 findSEHEHReturnPoints(F, EHReturnBlocks);
553 dbgs() << "identified the following blocks as EH return points:\n";
554 for (BasicBlock *BB : EHReturnBlocks)
555 dbgs() << " " << BB->getName() << '\n';
558 // Join points should not have phis at this point, unless they are a
559 // landingpad, in which case we will demote their phis later.
561 for (BasicBlock *BB : EHReturnBlocks)
562 assert((BB->isLandingPad() || !isa<PHINode>(BB->begin())) &&
563 "non-lpad EH return block has phi");
566 // Normal blocks are the blocks reachable from the entry block and all EH
568 Worklist = EHReturnBlocks;
569 Worklist.insert(&F.getEntryBlock());
570 findReachableBlocks(NormalBlocks, Worklist, nullptr);
572 dbgs() << "marked the following blocks as normal:\n";
573 for (BasicBlock *BB : NormalBlocks)
574 dbgs() << " " << BB->getName() << '\n';
577 // Exceptional blocks are the blocks reachable from landingpads that don't
578 // cross EH return points.
580 for (auto *LPI : LPads)
581 Worklist.insert(LPI->getParent());
582 findReachableBlocks(EHBlocks, Worklist, &EHReturnBlocks);
584 dbgs() << "marked the following blocks as exceptional:\n";
585 for (BasicBlock *BB : EHBlocks)
586 dbgs() << " " << BB->getName() << '\n';
589 SetVector<Argument *> ArgsToDemote;
590 SetVector<Instruction *> InstrsToDemote;
591 for (BasicBlock &BB : F) {
592 bool IsNormalBB = NormalBlocks.count(&BB);
593 bool IsEHBB = EHBlocks.count(&BB);
594 if (!IsNormalBB && !IsEHBB)
595 continue; // Blocks that are neither normal nor EH are unreachable.
596 for (Instruction &I : BB) {
597 for (Value *Op : I.operands()) {
598 // Don't demote static allocas, constants, and labels.
599 if (isa<Constant>(Op) || isa<BasicBlock>(Op) || isa<InlineAsm>(Op))
601 auto *AI = dyn_cast<AllocaInst>(Op);
602 if (AI && AI->isStaticAlloca())
605 if (auto *Arg = dyn_cast<Argument>(Op)) {
607 DEBUG(dbgs() << "Demoting argument " << *Arg
608 << " used by EH instr: " << I << "\n");
609 ArgsToDemote.insert(Arg);
614 auto *OpI = cast<Instruction>(Op);
615 BasicBlock *OpBB = OpI->getParent();
616 // If a value is produced and consumed in the same BB, we don't need to
620 bool IsOpNormalBB = NormalBlocks.count(OpBB);
621 bool IsOpEHBB = EHBlocks.count(OpBB);
622 if (IsNormalBB != IsOpNormalBB || IsEHBB != IsOpEHBB) {
624 dbgs() << "Demoting instruction live in-out from EH:\n";
625 dbgs() << "Instr: " << *OpI << '\n';
626 dbgs() << "User: " << I << '\n';
628 InstrsToDemote.insert(OpI);
634 // Demote values live into and out of handlers.
635 // FIXME: This demotion is inefficient. We should insert spills at the point
636 // of definition, insert one reload in each handler that uses the value, and
637 // insert reloads in the BB used to rejoin normal control flow.
638 Instruction *AllocaInsertPt = F.getEntryBlock().getFirstInsertionPt();
639 for (Instruction *I : InstrsToDemote)
640 DemoteRegToStack(*I, false, AllocaInsertPt);
642 // Demote arguments separately, and only for uses in EH blocks.
643 for (Argument *Arg : ArgsToDemote) {
644 auto *Slot = new AllocaInst(Arg->getType(), nullptr,
645 Arg->getName() + ".reg2mem", AllocaInsertPt);
646 SmallVector<User *, 4> Users(Arg->user_begin(), Arg->user_end());
647 for (User *U : Users) {
648 auto *I = dyn_cast<Instruction>(U);
649 if (I && EHBlocks.count(I->getParent())) {
650 auto *Reload = new LoadInst(Slot, Arg->getName() + ".reload", false, I);
651 U->replaceUsesOfWith(Arg, Reload);
654 new StoreInst(Arg, Slot, AllocaInsertPt);
657 // Demote landingpad phis, as the landingpad will be removed from the machine
659 for (LandingPadInst *LPI : LPads) {
660 BasicBlock *BB = LPI->getParent();
661 while (auto *Phi = dyn_cast<PHINode>(BB->begin()))
662 DemotePHIToStack(Phi, AllocaInsertPt);
665 DEBUG(dbgs() << "Demoted " << InstrsToDemote.size() << " instructions and "
666 << ArgsToDemote.size() << " arguments for WinEHPrepare\n\n");
669 bool WinEHPrepare::prepareExceptionHandlers(
670 Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
671 // Don't run on functions that are already prepared.
672 for (LandingPadInst *LPad : LPads) {
673 BasicBlock *LPadBB = LPad->getParent();
674 for (Instruction &Inst : *LPadBB)
675 if (match(&Inst, m_Intrinsic<Intrinsic::eh_actions>()))
679 demoteValuesLiveAcrossHandlers(F, LPads);
681 // These containers are used to re-map frame variables that are used in
682 // outlined catch and cleanup handlers. They will be populated as the
683 // handlers are outlined.
684 FrameVarInfoMap FrameVarInfo;
686 bool HandlersOutlined = false;
688 Module *M = F.getParent();
689 LLVMContext &Context = M->getContext();
691 // Create a new function to receive the handler contents.
692 PointerType *Int8PtrType = Type::getInt8PtrTy(Context);
693 Type *Int32Type = Type::getInt32Ty(Context);
694 Function *ActionIntrin = Intrinsic::getDeclaration(M, Intrinsic::eh_actions);
696 if (isAsynchronousEHPersonality(Personality)) {
697 // FIXME: Switch the ehptr type to i32 and then switch this.
698 SEHExceptionCodeSlot =
699 new AllocaInst(Int8PtrType, nullptr, "seh_exception_code",
700 F.getEntryBlock().getFirstInsertionPt());
703 for (LandingPadInst *LPad : LPads) {
704 // Look for evidence that this landingpad has already been processed.
705 bool LPadHasActionList = false;
706 BasicBlock *LPadBB = LPad->getParent();
707 for (Instruction &Inst : *LPadBB) {
708 if (match(&Inst, m_Intrinsic<Intrinsic::eh_actions>())) {
709 LPadHasActionList = true;
714 // If we've already outlined the handlers for this landingpad,
715 // there's nothing more to do here.
716 if (LPadHasActionList)
719 // If either of the values in the aggregate returned by the landing pad is
720 // extracted and stored to memory, promote the stored value to a register.
721 promoteLandingPadValues(LPad);
723 LandingPadActions Actions;
724 mapLandingPadBlocks(LPad, Actions);
726 HandlersOutlined |= !Actions.actions().empty();
727 for (ActionHandler *Action : Actions) {
728 if (Action->hasBeenProcessed())
730 BasicBlock *StartBB = Action->getStartBlock();
732 // SEH doesn't do any outlining for catches. Instead, pass the handler
733 // basic block addr to llvm.eh.actions and list the block as a return
735 if (isAsynchronousEHPersonality(Personality)) {
736 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
737 processSEHCatchHandler(CatchAction, StartBB);
742 outlineHandler(Action, &F, LPad, StartBB, FrameVarInfo);
745 // Split the block after the landingpad instruction so that it is just a
746 // call to llvm.eh.actions followed by indirectbr.
747 assert(!isa<PHINode>(LPadBB->begin()) && "lpad phi not removed");
748 SplitBlock(LPadBB, LPad->getNextNode(), DT);
749 // Erase the branch inserted by the split so we can insert indirectbr.
750 LPadBB->getTerminator()->eraseFromParent();
752 // Replace all extracted values with undef and ultimately replace the
753 // landingpad with undef.
754 SmallVector<Instruction *, 4> SEHCodeUses;
755 SmallVector<Instruction *, 4> EHUndefs;
756 for (User *U : LPad->users()) {
757 auto *E = dyn_cast<ExtractValueInst>(U);
760 assert(E->getNumIndices() == 1 &&
761 "Unexpected operation: extracting both landing pad values");
762 unsigned Idx = *E->idx_begin();
763 assert((Idx == 0 || Idx == 1) && "unexpected index");
764 if (Idx == 0 && isAsynchronousEHPersonality(Personality))
765 SEHCodeUses.push_back(E);
767 EHUndefs.push_back(E);
769 for (Instruction *E : EHUndefs) {
770 E->replaceAllUsesWith(UndefValue::get(E->getType()));
771 E->eraseFromParent();
773 LPad->replaceAllUsesWith(UndefValue::get(LPad->getType()));
775 // Rewrite uses of the exception pointer to loads of an alloca.
776 for (Instruction *E : SEHCodeUses) {
777 SmallVector<Use *, 4> Uses;
778 for (Use &U : E->uses())
780 for (Use *U : Uses) {
781 auto *I = cast<Instruction>(U->getUser());
782 if (isa<ResumeInst>(I))
785 if (auto *Phi = dyn_cast<PHINode>(I))
786 LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false,
787 Phi->getIncomingBlock(*U));
789 LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false, I);
792 E->replaceAllUsesWith(UndefValue::get(E->getType()));
793 E->eraseFromParent();
796 // Add a call to describe the actions for this landing pad.
797 std::vector<Value *> ActionArgs;
798 for (ActionHandler *Action : Actions) {
799 // Action codes from docs are: 0 cleanup, 1 catch.
800 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
801 ActionArgs.push_back(ConstantInt::get(Int32Type, 1));
802 ActionArgs.push_back(CatchAction->getSelector());
803 // Find the frame escape index of the exception object alloca in the
805 int FrameEscapeIdx = -1;
806 Value *EHObj = const_cast<Value *>(CatchAction->getExceptionVar());
807 if (EHObj && !isa<ConstantPointerNull>(EHObj)) {
808 auto I = FrameVarInfo.find(EHObj);
809 assert(I != FrameVarInfo.end() &&
810 "failed to map llvm.eh.begincatch var");
811 FrameEscapeIdx = std::distance(FrameVarInfo.begin(), I);
813 ActionArgs.push_back(ConstantInt::get(Int32Type, FrameEscapeIdx));
815 ActionArgs.push_back(ConstantInt::get(Int32Type, 0));
817 ActionArgs.push_back(Action->getHandlerBlockOrFunc());
820 CallInst::Create(ActionIntrin, ActionArgs, "recover", LPadBB);
822 // Add an indirect branch listing possible successors of the catch handlers.
823 SetVector<BasicBlock *> ReturnTargets;
824 for (ActionHandler *Action : Actions) {
825 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
826 const auto &CatchTargets = CatchAction->getReturnTargets();
827 ReturnTargets.insert(CatchTargets.begin(), CatchTargets.end());
830 IndirectBrInst *Branch =
831 IndirectBrInst::Create(Recover, ReturnTargets.size(), LPadBB);
832 for (BasicBlock *Target : ReturnTargets)
833 Branch->addDestination(Target);
834 } // End for each landingpad
836 // If nothing got outlined, there is no more processing to be done.
837 if (!HandlersOutlined)
840 // Replace any nested landing pad stubs with the correct action handler.
841 // This must be done before we remove unreachable blocks because it
842 // cleans up references to outlined blocks that will be deleted.
843 for (auto &LPadPair : NestedLPtoOriginalLP)
844 completeNestedLandingPad(&F, LPadPair.first, LPadPair.second, FrameVarInfo);
845 NestedLPtoOriginalLP.clear();
847 F.addFnAttr("wineh-parent", F.getName());
849 // Delete any blocks that were only used by handlers that were outlined above.
850 removeUnreachableBlocks(F);
852 BasicBlock *Entry = &F.getEntryBlock();
853 IRBuilder<> Builder(F.getParent()->getContext());
854 Builder.SetInsertPoint(Entry->getFirstInsertionPt());
856 Function *FrameEscapeFn =
857 Intrinsic::getDeclaration(M, Intrinsic::frameescape);
858 Function *RecoverFrameFn =
859 Intrinsic::getDeclaration(M, Intrinsic::framerecover);
860 SmallVector<Value *, 8> AllocasToEscape;
862 // Scan the entry block for an existing call to llvm.frameescape. We need to
863 // keep escaping those objects.
864 for (Instruction &I : F.front()) {
865 auto *II = dyn_cast<IntrinsicInst>(&I);
866 if (II && II->getIntrinsicID() == Intrinsic::frameescape) {
867 auto Args = II->arg_operands();
868 AllocasToEscape.append(Args.begin(), Args.end());
869 II->eraseFromParent();
874 // Finally, replace all of the temporary allocas for frame variables used in
875 // the outlined handlers with calls to llvm.framerecover.
876 for (auto &VarInfoEntry : FrameVarInfo) {
877 Value *ParentVal = VarInfoEntry.first;
878 TinyPtrVector<AllocaInst *> &Allocas = VarInfoEntry.second;
879 AllocaInst *ParentAlloca = cast<AllocaInst>(ParentVal);
881 // FIXME: We should try to sink unescaped allocas from the parent frame into
882 // the child frame. If the alloca is escaped, we have to use the lifetime
883 // markers to ensure that the alloca is only live within the child frame.
885 // Add this alloca to the list of things to escape.
886 AllocasToEscape.push_back(ParentAlloca);
888 // Next replace all outlined allocas that are mapped to it.
889 for (AllocaInst *TempAlloca : Allocas) {
890 if (TempAlloca == getCatchObjectSentinel())
891 continue; // Skip catch parameter sentinels.
892 Function *HandlerFn = TempAlloca->getParent()->getParent();
893 llvm::Value *FP = HandlerToParentFP[HandlerFn];
896 // FIXME: Sink this framerecover into the blocks where it is used.
897 Builder.SetInsertPoint(TempAlloca);
898 Builder.SetCurrentDebugLocation(TempAlloca->getDebugLoc());
899 Value *RecoverArgs[] = {
900 Builder.CreateBitCast(&F, Int8PtrType, ""), FP,
901 llvm::ConstantInt::get(Int32Type, AllocasToEscape.size() - 1)};
902 Instruction *RecoveredAlloca =
903 Builder.CreateCall(RecoverFrameFn, RecoverArgs);
905 // Add a pointer bitcast if the alloca wasn't an i8.
906 if (RecoveredAlloca->getType() != TempAlloca->getType()) {
907 RecoveredAlloca->setName(Twine(TempAlloca->getName()) + ".i8");
908 RecoveredAlloca = cast<Instruction>(
909 Builder.CreateBitCast(RecoveredAlloca, TempAlloca->getType()));
911 TempAlloca->replaceAllUsesWith(RecoveredAlloca);
912 TempAlloca->removeFromParent();
913 RecoveredAlloca->takeName(TempAlloca);
916 } // End for each FrameVarInfo entry.
918 // Insert 'call void (...)* @llvm.frameescape(...)' at the end of the entry
920 Builder.SetInsertPoint(&F.getEntryBlock().back());
921 Builder.CreateCall(FrameEscapeFn, AllocasToEscape);
923 if (SEHExceptionCodeSlot) {
924 if (SEHExceptionCodeSlot->hasNUses(0))
925 SEHExceptionCodeSlot->eraseFromParent();
926 else if (isAllocaPromotable(SEHExceptionCodeSlot))
927 PromoteMemToReg(SEHExceptionCodeSlot, *DT);
930 // Clean up the handler action maps we created for this function
931 DeleteContainerSeconds(CatchHandlerMap);
932 CatchHandlerMap.clear();
933 DeleteContainerSeconds(CleanupHandlerMap);
934 CleanupHandlerMap.clear();
935 HandlerToParentFP.clear();
937 SEHExceptionCodeSlot = nullptr;
939 return HandlersOutlined;
942 void WinEHPrepare::promoteLandingPadValues(LandingPadInst *LPad) {
943 // If the return values of the landing pad instruction are extracted and
944 // stored to memory, we want to promote the store locations to reg values.
945 SmallVector<AllocaInst *, 2> EHAllocas;
947 // The landingpad instruction returns an aggregate value. Typically, its
948 // value will be passed to a pair of extract value instructions and the
949 // results of those extracts are often passed to store instructions.
950 // In unoptimized code the stored value will often be loaded and then stored
952 for (auto *U : LPad->users()) {
953 ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
957 for (auto *EU : Extract->users()) {
958 if (auto *Store = dyn_cast<StoreInst>(EU)) {
959 auto *AV = cast<AllocaInst>(Store->getPointerOperand());
960 EHAllocas.push_back(AV);
965 // We can't do this without a dominator tree.
968 if (!EHAllocas.empty()) {
969 PromoteMemToReg(EHAllocas, *DT);
973 // After promotion, some extracts may be trivially dead. Remove them.
974 SmallVector<Value *, 4> Users(LPad->user_begin(), LPad->user_end());
975 for (auto *U : Users)
976 RecursivelyDeleteTriviallyDeadInstructions(U);
979 void WinEHPrepare::completeNestedLandingPad(Function *ParentFn,
980 LandingPadInst *OutlinedLPad,
981 const LandingPadInst *OriginalLPad,
982 FrameVarInfoMap &FrameVarInfo) {
983 // Get the nested block and erase the unreachable instruction that was
984 // temporarily inserted as its terminator.
985 LLVMContext &Context = ParentFn->getContext();
986 BasicBlock *OutlinedBB = OutlinedLPad->getParent();
987 assert(isa<UnreachableInst>(OutlinedBB->getTerminator()));
988 OutlinedBB->getTerminator()->eraseFromParent();
989 // That should leave OutlinedLPad as the last instruction in its block.
990 assert(&OutlinedBB->back() == OutlinedLPad);
992 // The original landing pad will have already had its action intrinsic
993 // built by the outlining loop. We need to clone that into the outlined
994 // location. It may also be necessary to add references to the exception
995 // variables to the outlined handler in which this landing pad is nested
996 // and remap return instructions in the nested handlers that should return
997 // to an address in the outlined handler.
998 Function *OutlinedHandlerFn = OutlinedBB->getParent();
999 BasicBlock::const_iterator II = OriginalLPad;
1001 // The instruction after the landing pad should now be a call to eh.actions.
1002 const Instruction *Recover = II;
1003 assert(match(Recover, m_Intrinsic<Intrinsic::eh_actions>()));
1004 IntrinsicInst *EHActions = cast<IntrinsicInst>(Recover->clone());
1006 // Remap the exception variables into the outlined function.
1007 SmallVector<BlockAddress *, 4> ActionTargets;
1008 SmallVector<ActionHandler *, 4> ActionList;
1009 parseEHActions(EHActions, ActionList);
1010 for (auto *Action : ActionList) {
1011 auto *Catch = dyn_cast<CatchHandler>(Action);
1014 // The dyn_cast to function here selects C++ catch handlers and skips
1015 // SEH catch handlers.
1016 auto *Handler = dyn_cast<Function>(Catch->getHandlerBlockOrFunc());
1019 // Visit all the return instructions, looking for places that return
1020 // to a location within OutlinedHandlerFn.
1021 for (BasicBlock &NestedHandlerBB : *Handler) {
1022 auto *Ret = dyn_cast<ReturnInst>(NestedHandlerBB.getTerminator());
1026 // Handler functions must always return a block address.
1027 BlockAddress *BA = cast<BlockAddress>(Ret->getReturnValue());
1028 // The original target will have been in the main parent function,
1029 // but if it is the address of a block that has been outlined, it
1030 // should be a block that was outlined into OutlinedHandlerFn.
1031 assert(BA->getFunction() == ParentFn);
1033 // Ignore targets that aren't part of OutlinedHandlerFn.
1034 if (!LPadTargetBlocks.count(BA->getBasicBlock()))
1037 // If the return value is the address ofF a block that we
1038 // previously outlined into the parent handler function, replace
1039 // the return instruction and add the mapped target to the list
1040 // of possible return addresses.
1041 BasicBlock *MappedBB = LPadTargetBlocks[BA->getBasicBlock()];
1042 assert(MappedBB->getParent() == OutlinedHandlerFn);
1043 BlockAddress *NewBA = BlockAddress::get(OutlinedHandlerFn, MappedBB);
1044 Ret->eraseFromParent();
1045 ReturnInst::Create(Context, NewBA, &NestedHandlerBB);
1046 ActionTargets.push_back(NewBA);
1049 DeleteContainerPointers(ActionList);
1051 OutlinedBB->getInstList().push_back(EHActions);
1053 // Insert an indirect branch into the outlined landing pad BB.
1054 IndirectBrInst *IBr = IndirectBrInst::Create(EHActions, 0, OutlinedBB);
1055 // Add the previously collected action targets.
1056 for (auto *Target : ActionTargets)
1057 IBr->addDestination(Target->getBasicBlock());
1060 // This function examines a block to determine whether the block ends with a
1061 // conditional branch to a catch handler based on a selector comparison.
1062 // This function is used both by the WinEHPrepare::findSelectorComparison() and
1063 // WinEHCleanupDirector::handleTypeIdFor().
1064 static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler,
1065 Constant *&Selector, BasicBlock *&NextBB) {
1066 ICmpInst::Predicate Pred;
1067 BasicBlock *TBB, *FBB;
1070 if (!match(BB->getTerminator(),
1071 m_Br(m_ICmp(Pred, m_Value(LHS), m_Value(RHS)), TBB, FBB)))
1075 m_Intrinsic<Intrinsic::eh_typeid_for>(m_Constant(Selector))) &&
1076 !match(RHS, m_Intrinsic<Intrinsic::eh_typeid_for>(m_Constant(Selector))))
1079 if (Pred == CmpInst::ICMP_EQ) {
1085 if (Pred == CmpInst::ICMP_NE) {
1094 static bool isCatchBlock(BasicBlock *BB) {
1095 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
1097 if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_begincatch>()))
1103 static BasicBlock *createStubLandingPad(Function *Handler,
1104 Value *PersonalityFn) {
1105 // FIXME: Finish this!
1106 LLVMContext &Context = Handler->getContext();
1107 BasicBlock *StubBB = BasicBlock::Create(Context, "stub");
1108 Handler->getBasicBlockList().push_back(StubBB);
1109 IRBuilder<> Builder(StubBB);
1110 LandingPadInst *LPad = Builder.CreateLandingPad(
1111 llvm::StructType::get(Type::getInt8PtrTy(Context),
1112 Type::getInt32Ty(Context), nullptr),
1114 // Insert a call to llvm.eh.actions so that we don't try to outline this lpad.
1115 Function *ActionIntrin =
1116 Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::eh_actions);
1117 Builder.CreateCall(ActionIntrin, "recover");
1118 LPad->setCleanup(true);
1119 Builder.CreateUnreachable();
1123 // Cycles through the blocks in an outlined handler function looking for an
1124 // invoke instruction and inserts an invoke of llvm.donothing with an empty
1125 // landing pad if none is found. The code that generates the .xdata tables for
1126 // the handler needs at least one landing pad to identify the parent function's
1128 void WinEHPrepare::addStubInvokeToHandlerIfNeeded(Function *Handler,
1129 Value *PersonalityFn) {
1130 ReturnInst *Ret = nullptr;
1131 UnreachableInst *Unreached = nullptr;
1132 for (BasicBlock &BB : *Handler) {
1133 TerminatorInst *Terminator = BB.getTerminator();
1134 // If we find an invoke, there is nothing to be done.
1135 auto *II = dyn_cast<InvokeInst>(Terminator);
1138 // If we've already recorded a return instruction, keep looking for invokes.
1140 Ret = dyn_cast<ReturnInst>(Terminator);
1141 // If we haven't recorded an unreachable instruction, try this terminator.
1143 Unreached = dyn_cast<UnreachableInst>(Terminator);
1146 // If we got this far, the handler contains no invokes. We should have seen
1147 // at least one return or unreachable instruction. We'll insert an invoke of
1148 // llvm.donothing ahead of that instruction.
1149 assert(Ret || Unreached);
1150 TerminatorInst *Term;
1155 BasicBlock *OldRetBB = Term->getParent();
1156 BasicBlock *NewRetBB = SplitBlock(OldRetBB, Term, DT);
1157 // SplitBlock adds an unconditional branch instruction at the end of the
1158 // parent block. We want to replace that with an invoke call, so we can
1160 OldRetBB->getTerminator()->eraseFromParent();
1161 BasicBlock *StubLandingPad = createStubLandingPad(Handler, PersonalityFn);
1163 Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::donothing);
1164 InvokeInst::Create(F, NewRetBB, StubLandingPad, None, "", OldRetBB);
1167 // FIXME: Consider sinking this into lib/Target/X86 somehow. TargetLowering
1168 // usually doesn't build LLVM IR, so that's probably the wrong place.
1169 Function *WinEHPrepare::createHandlerFunc(Type *RetTy, const Twine &Name,
1170 Module *M, Value *&ParentFP) {
1171 // x64 uses a two-argument prototype where the parent FP is the second
1172 // argument. x86 uses no arguments, just the incoming EBP value.
1173 LLVMContext &Context = M->getContext();
1174 FunctionType *FnType;
1175 if (TheTriple.getArch() == Triple::x86_64) {
1176 Type *Int8PtrType = Type::getInt8PtrTy(Context);
1177 Type *ArgTys[2] = {Int8PtrType, Int8PtrType};
1178 FnType = FunctionType::get(RetTy, ArgTys, false);
1180 FnType = FunctionType::get(RetTy, None, false);
1184 Function::Create(FnType, GlobalVariable::InternalLinkage, Name, M);
1185 BasicBlock *Entry = BasicBlock::Create(Context, "entry");
1186 Handler->getBasicBlockList().push_front(Entry);
1187 if (TheTriple.getArch() == Triple::x86_64) {
1188 ParentFP = &(Handler->getArgumentList().back());
1191 Function *FrameAddressFn =
1192 Intrinsic::getDeclaration(M, Intrinsic::frameaddress);
1193 Value *Args[1] = {ConstantInt::get(Type::getInt32Ty(Context), 1)};
1194 ParentFP = CallInst::Create(FrameAddressFn, Args, "parent_fp",
1195 &Handler->getEntryBlock());
1200 bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn,
1201 LandingPadInst *LPad, BasicBlock *StartBB,
1202 FrameVarInfoMap &VarInfo) {
1203 Module *M = SrcFn->getParent();
1204 LLVMContext &Context = M->getContext();
1205 Type *Int8PtrType = Type::getInt8PtrTy(Context);
1207 // Create a new function to receive the handler contents.
1210 if (Action->getType() == Catch) {
1211 Handler = createHandlerFunc(Int8PtrType, SrcFn->getName() + ".catch", M,
1214 Handler = createHandlerFunc(Type::getVoidTy(Context),
1215 SrcFn->getName() + ".cleanup", M, ParentFP);
1217 HandlerToParentFP[Handler] = ParentFP;
1218 Handler->addFnAttr("wineh-parent", SrcFn->getName());
1219 BasicBlock *Entry = &Handler->getEntryBlock();
1221 // Generate a standard prolog to setup the frame recovery structure.
1222 IRBuilder<> Builder(Context);
1223 Builder.SetInsertPoint(Entry);
1224 Builder.SetCurrentDebugLocation(LPad->getDebugLoc());
1226 std::unique_ptr<WinEHCloningDirectorBase> Director;
1228 ValueToValueMapTy VMap;
1230 LandingPadMap &LPadMap = LPadMaps[LPad];
1231 if (!LPadMap.isInitialized())
1232 LPadMap.mapLandingPad(LPad);
1233 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
1234 Constant *Sel = CatchAction->getSelector();
1235 Director.reset(new WinEHCatchDirector(Handler, ParentFP, Sel,
1237 NestedLPtoOriginalLP));
1238 LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
1239 ConstantInt::get(Type::getInt32Ty(Context), 1));
1242 new WinEHCleanupDirector(Handler, ParentFP, VarInfo, LPadMap));
1243 LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
1244 UndefValue::get(Type::getInt32Ty(Context)));
1247 SmallVector<ReturnInst *, 8> Returns;
1248 ClonedCodeInfo OutlinedFunctionInfo;
1250 // If the start block contains PHI nodes, we need to map them.
1251 BasicBlock::iterator II = StartBB->begin();
1252 while (auto *PN = dyn_cast<PHINode>(II)) {
1253 bool Mapped = false;
1254 // Look for PHI values that we have already mapped (such as the selector).
1255 for (Value *Val : PN->incoming_values()) {
1256 if (VMap.count(Val)) {
1257 VMap[PN] = VMap[Val];
1261 // If we didn't find a match for this value, map it as an undef.
1263 VMap[PN] = UndefValue::get(PN->getType());
1268 // The landing pad value may be used by PHI nodes. It will ultimately be
1269 // eliminated, but we need it in the map for intermediate handling.
1270 VMap[LPad] = UndefValue::get(LPad->getType());
1272 // Skip over PHIs and, if applicable, landingpad instructions.
1273 II = StartBB->getFirstInsertionPt();
1275 CloneAndPruneIntoFromInst(Handler, SrcFn, II, VMap,
1276 /*ModuleLevelChanges=*/false, Returns, "",
1277 &OutlinedFunctionInfo, Director.get());
1279 // Move all the instructions in the cloned "entry" block into our entry block.
1280 // Depending on how the parent function was laid out, the block that will
1281 // correspond to the outlined entry block may not be the first block in the
1282 // list. We can recognize it, however, as the cloned block which has no
1283 // predecessors. Any other block wouldn't have been cloned if it didn't
1284 // have a predecessor which was also cloned.
1285 Function::iterator ClonedIt = std::next(Function::iterator(Entry));
1286 while (!pred_empty(ClonedIt))
1288 BasicBlock *ClonedEntryBB = ClonedIt;
1289 assert(ClonedEntryBB);
1290 Entry->getInstList().splice(Entry->end(), ClonedEntryBB->getInstList());
1291 ClonedEntryBB->eraseFromParent();
1293 // Make sure we can identify the handler's personality later.
1294 addStubInvokeToHandlerIfNeeded(Handler, LPad->getPersonalityFn());
1296 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
1297 WinEHCatchDirector *CatchDirector =
1298 reinterpret_cast<WinEHCatchDirector *>(Director.get());
1299 CatchAction->setExceptionVar(CatchDirector->getExceptionVar());
1300 CatchAction->setReturnTargets(CatchDirector->getReturnTargets());
1302 // Look for blocks that are not part of the landing pad that we just
1303 // outlined but terminate with a call to llvm.eh.endcatch and a
1304 // branch to a block that is in the handler we just outlined.
1305 // These blocks will be part of a nested landing pad that intends to
1306 // return to an address in this handler. This case is best handled
1307 // after both landing pads have been outlined, so for now we'll just
1308 // save the association of the blocks in LPadTargetBlocks. The
1309 // return instructions which are created from these branches will be
1310 // replaced after all landing pads have been outlined.
1311 for (const auto MapEntry : VMap) {
1312 // VMap maps all values and blocks that were just cloned, but dead
1313 // blocks which were pruned will map to nullptr.
1314 if (!isa<BasicBlock>(MapEntry.first) || MapEntry.second == nullptr)
1316 const BasicBlock *MappedBB = cast<BasicBlock>(MapEntry.first);
1317 for (auto *Pred : predecessors(const_cast<BasicBlock *>(MappedBB))) {
1318 auto *Branch = dyn_cast<BranchInst>(Pred->getTerminator());
1319 if (!Branch || !Branch->isUnconditional() || Pred->size() <= 1)
1321 BasicBlock::iterator II = const_cast<BranchInst *>(Branch);
1323 if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_endcatch>())) {
1324 // This would indicate that a nested landing pad wants to return
1325 // to a block that is outlined into two different handlers.
1326 assert(!LPadTargetBlocks.count(MappedBB));
1327 LPadTargetBlocks[MappedBB] = cast<BasicBlock>(MapEntry.second);
1331 } // End if (CatchAction)
1333 Action->setHandlerBlockOrFunc(Handler);
1338 /// This BB must end in a selector dispatch. All we need to do is pass the
1339 /// handler block to llvm.eh.actions and list it as a possible indirectbr
1341 void WinEHPrepare::processSEHCatchHandler(CatchHandler *CatchAction,
1342 BasicBlock *StartBB) {
1343 BasicBlock *HandlerBB;
1346 bool Res = isSelectorDispatch(StartBB, HandlerBB, Selector, NextBB);
1348 // If this was EH dispatch, this must be a conditional branch to the handler
1350 // FIXME: Handle instructions in the dispatch block. Currently we drop them,
1351 // leading to crashes if some optimization hoists stuff here.
1352 assert(CatchAction->getSelector() && HandlerBB &&
1353 "expected catch EH dispatch");
1355 // This must be a catch-all. Split the block after the landingpad.
1356 assert(CatchAction->getSelector()->isNullValue() && "expected catch-all");
1357 HandlerBB = SplitBlock(StartBB, StartBB->getFirstInsertionPt(), DT);
1359 IRBuilder<> Builder(HandlerBB->getFirstInsertionPt());
1360 Function *EHCodeFn = Intrinsic::getDeclaration(
1361 StartBB->getParent()->getParent(), Intrinsic::eh_exceptioncode);
1362 Value *Code = Builder.CreateCall(EHCodeFn, "sehcode");
1363 Code = Builder.CreateIntToPtr(Code, SEHExceptionCodeSlot->getAllocatedType());
1364 Builder.CreateStore(Code, SEHExceptionCodeSlot);
1365 CatchAction->setHandlerBlockOrFunc(BlockAddress::get(HandlerBB));
1366 TinyPtrVector<BasicBlock *> Targets(HandlerBB);
1367 CatchAction->setReturnTargets(Targets);
1370 void LandingPadMap::mapLandingPad(const LandingPadInst *LPad) {
1371 // Each instance of this class should only ever be used to map a single
1373 assert(OriginLPad == nullptr || OriginLPad == LPad);
1375 // If the landing pad has already been mapped, there's nothing more to do.
1376 if (OriginLPad == LPad)
1381 // The landingpad instruction returns an aggregate value. Typically, its
1382 // value will be passed to a pair of extract value instructions and the
1383 // results of those extracts will have been promoted to reg values before
1384 // this routine is called.
1385 for (auto *U : LPad->users()) {
1386 const ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
1389 assert(Extract->getNumIndices() == 1 &&
1390 "Unexpected operation: extracting both landing pad values");
1391 unsigned int Idx = *(Extract->idx_begin());
1392 assert((Idx == 0 || Idx == 1) &&
1393 "Unexpected operation: extracting an unknown landing pad element");
1395 ExtractedEHPtrs.push_back(Extract);
1396 } else if (Idx == 1) {
1397 ExtractedSelectors.push_back(Extract);
1402 bool LandingPadMap::isOriginLandingPadBlock(const BasicBlock *BB) const {
1403 return BB->getLandingPadInst() == OriginLPad;
1406 bool LandingPadMap::isLandingPadSpecificInst(const Instruction *Inst) const {
1407 if (Inst == OriginLPad)
1409 for (auto *Extract : ExtractedEHPtrs) {
1410 if (Inst == Extract)
1413 for (auto *Extract : ExtractedSelectors) {
1414 if (Inst == Extract)
1420 void LandingPadMap::remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
1421 Value *SelectorValue) const {
1422 // Remap all landing pad extract instructions to the specified values.
1423 for (auto *Extract : ExtractedEHPtrs)
1424 VMap[Extract] = EHPtrValue;
1425 for (auto *Extract : ExtractedSelectors)
1426 VMap[Extract] = SelectorValue;
1429 static bool isFrameAddressCall(const Value *V) {
1430 return match(const_cast<Value *>(V),
1431 m_Intrinsic<Intrinsic::frameaddress>(m_SpecificInt(0)));
1434 CloningDirector::CloningAction WinEHCloningDirectorBase::handleInstruction(
1435 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1436 // If this is one of the boilerplate landing pad instructions, skip it.
1437 // The instruction will have already been remapped in VMap.
1438 if (LPadMap.isLandingPadSpecificInst(Inst))
1439 return CloningDirector::SkipInstruction;
1441 // Nested landing pads will be cloned as stubs, with just the
1442 // landingpad instruction and an unreachable instruction. When
1443 // all landingpads have been outlined, we'll replace this with the
1444 // llvm.eh.actions call and indirect branch created when the
1445 // landing pad was outlined.
1446 if (auto *LPad = dyn_cast<LandingPadInst>(Inst)) {
1447 return handleLandingPad(VMap, LPad, NewBB);
1450 if (auto *Invoke = dyn_cast<InvokeInst>(Inst))
1451 return handleInvoke(VMap, Invoke, NewBB);
1453 if (auto *Resume = dyn_cast<ResumeInst>(Inst))
1454 return handleResume(VMap, Resume, NewBB);
1456 if (auto *Cmp = dyn_cast<CmpInst>(Inst))
1457 return handleCompare(VMap, Cmp, NewBB);
1459 if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>()))
1460 return handleBeginCatch(VMap, Inst, NewBB);
1461 if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
1462 return handleEndCatch(VMap, Inst, NewBB);
1463 if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
1464 return handleTypeIdFor(VMap, Inst, NewBB);
1466 // When outlining llvm.frameaddress(i32 0), remap that to the second argument,
1467 // which is the FP of the parent.
1468 if (isFrameAddressCall(Inst)) {
1469 VMap[Inst] = ParentFP;
1470 return CloningDirector::SkipInstruction;
1473 // Continue with the default cloning behavior.
1474 return CloningDirector::CloneInstruction;
1477 CloningDirector::CloningAction WinEHCatchDirector::handleLandingPad(
1478 ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
1479 Instruction *NewInst = LPad->clone();
1480 if (LPad->hasName())
1481 NewInst->setName(LPad->getName());
1482 // Save this correlation for later processing.
1483 NestedLPtoOriginalLP[cast<LandingPadInst>(NewInst)] = LPad;
1484 VMap[LPad] = NewInst;
1485 BasicBlock::InstListType &InstList = NewBB->getInstList();
1486 InstList.push_back(NewInst);
1487 InstList.push_back(new UnreachableInst(NewBB->getContext()));
1488 return CloningDirector::StopCloningBB;
1491 CloningDirector::CloningAction WinEHCatchDirector::handleBeginCatch(
1492 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1493 // The argument to the call is some form of the first element of the
1494 // landingpad aggregate value, but that doesn't matter. It isn't used
1496 // The second argument is an outparameter where the exception object will be
1497 // stored. Typically the exception object is a scalar, but it can be an
1498 // aggregate when catching by value.
1499 // FIXME: Leave something behind to indicate where the exception object lives
1500 // for this handler. Should it be part of llvm.eh.actions?
1501 assert(ExceptionObjectVar == nullptr && "Multiple calls to "
1502 "llvm.eh.begincatch found while "
1503 "outlining catch handler.");
1504 ExceptionObjectVar = Inst->getOperand(1)->stripPointerCasts();
1505 if (isa<ConstantPointerNull>(ExceptionObjectVar))
1506 return CloningDirector::SkipInstruction;
1507 assert(cast<AllocaInst>(ExceptionObjectVar)->isStaticAlloca() &&
1508 "catch parameter is not static alloca");
1509 Materializer.escapeCatchObject(ExceptionObjectVar);
1510 return CloningDirector::SkipInstruction;
1513 CloningDirector::CloningAction
1514 WinEHCatchDirector::handleEndCatch(ValueToValueMapTy &VMap,
1515 const Instruction *Inst, BasicBlock *NewBB) {
1516 auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst);
1517 // It might be interesting to track whether or not we are inside a catch
1518 // function, but that might make the algorithm more brittle than it needs
1521 // The end catch call can occur in one of two places: either in a
1522 // landingpad block that is part of the catch handlers exception mechanism,
1523 // or at the end of the catch block. However, a catch-all handler may call
1524 // end catch from the original landing pad. If the call occurs in a nested
1525 // landing pad block, we must skip it and continue so that the landing pad
1527 auto *ParentBB = IntrinCall->getParent();
1528 if (ParentBB->isLandingPad() && !LPadMap.isOriginLandingPadBlock(ParentBB))
1529 return CloningDirector::SkipInstruction;
1531 // If an end catch occurs anywhere else we want to terminate the handler
1532 // with a return to the code that follows the endcatch call. If the
1533 // next instruction is not an unconditional branch, we need to split the
1534 // block to provide a clear target for the return instruction.
1535 BasicBlock *ContinueBB;
1536 auto Next = std::next(BasicBlock::const_iterator(IntrinCall));
1537 const BranchInst *Branch = dyn_cast<BranchInst>(Next);
1538 if (!Branch || !Branch->isUnconditional()) {
1539 // We're interrupting the cloning process at this location, so the
1540 // const_cast we're doing here will not cause a problem.
1541 ContinueBB = SplitBlock(const_cast<BasicBlock *>(ParentBB),
1542 const_cast<Instruction *>(cast<Instruction>(Next)));
1544 ContinueBB = Branch->getSuccessor(0);
1547 ReturnInst::Create(NewBB->getContext(), BlockAddress::get(ContinueBB), NewBB);
1548 ReturnTargets.push_back(ContinueBB);
1550 // We just added a terminator to the cloned block.
1551 // Tell the caller to stop processing the current basic block so that
1552 // the branch instruction will be skipped.
1553 return CloningDirector::StopCloningBB;
1556 CloningDirector::CloningAction WinEHCatchDirector::handleTypeIdFor(
1557 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1558 auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst);
1559 Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts();
1560 // This causes a replacement that will collapse the landing pad CFG based
1561 // on the filter function we intend to match.
1562 if (Selector == CurrentSelector)
1563 VMap[Inst] = ConstantInt::get(SelectorIDType, 1);
1565 VMap[Inst] = ConstantInt::get(SelectorIDType, 0);
1566 // Tell the caller not to clone this instruction.
1567 return CloningDirector::SkipInstruction;
1570 CloningDirector::CloningAction
1571 WinEHCatchDirector::handleInvoke(ValueToValueMapTy &VMap,
1572 const InvokeInst *Invoke, BasicBlock *NewBB) {
1573 return CloningDirector::CloneInstruction;
1576 CloningDirector::CloningAction
1577 WinEHCatchDirector::handleResume(ValueToValueMapTy &VMap,
1578 const ResumeInst *Resume, BasicBlock *NewBB) {
1579 // Resume instructions shouldn't be reachable from catch handlers.
1580 // We still need to handle it, but it will be pruned.
1581 BasicBlock::InstListType &InstList = NewBB->getInstList();
1582 InstList.push_back(new UnreachableInst(NewBB->getContext()));
1583 return CloningDirector::StopCloningBB;
1586 CloningDirector::CloningAction
1587 WinEHCatchDirector::handleCompare(ValueToValueMapTy &VMap,
1588 const CmpInst *Compare, BasicBlock *NewBB) {
1589 const IntrinsicInst *IntrinCall = nullptr;
1590 if (match(Compare->getOperand(0), m_Intrinsic<Intrinsic::eh_typeid_for>())) {
1591 IntrinCall = dyn_cast<IntrinsicInst>(Compare->getOperand(0));
1592 } else if (match(Compare->getOperand(1),
1593 m_Intrinsic<Intrinsic::eh_typeid_for>())) {
1594 IntrinCall = dyn_cast<IntrinsicInst>(Compare->getOperand(1));
1597 Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts();
1598 // This causes a replacement that will collapse the landing pad CFG based
1599 // on the filter function we intend to match.
1600 if (Selector == CurrentSelector->stripPointerCasts()) {
1601 VMap[Compare] = ConstantInt::get(SelectorIDType, 1);
1603 VMap[Compare] = ConstantInt::get(SelectorIDType, 0);
1605 return CloningDirector::SkipInstruction;
1607 return CloningDirector::CloneInstruction;
1610 CloningDirector::CloningAction WinEHCleanupDirector::handleLandingPad(
1611 ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
1612 // The MS runtime will terminate the process if an exception occurs in a
1613 // cleanup handler, so we shouldn't encounter landing pads in the actual
1614 // cleanup code, but they may appear in catch blocks. Depending on where
1615 // we started cloning we may see one, but it will get dropped during dead
1617 Instruction *NewInst = new UnreachableInst(NewBB->getContext());
1618 VMap[LPad] = NewInst;
1619 BasicBlock::InstListType &InstList = NewBB->getInstList();
1620 InstList.push_back(NewInst);
1621 return CloningDirector::StopCloningBB;
1624 CloningDirector::CloningAction WinEHCleanupDirector::handleBeginCatch(
1625 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1626 // Cleanup code may flow into catch blocks or the catch block may be part
1627 // of a branch that will be optimized away. We'll insert a return
1628 // instruction now, but it may be pruned before the cloning process is
1630 ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
1631 return CloningDirector::StopCloningBB;
1634 CloningDirector::CloningAction WinEHCleanupDirector::handleEndCatch(
1635 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1636 // Cleanup handlers nested within catch handlers may begin with a call to
1637 // eh.endcatch. We can just ignore that instruction.
1638 return CloningDirector::SkipInstruction;
1641 CloningDirector::CloningAction WinEHCleanupDirector::handleTypeIdFor(
1642 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1643 // If we encounter a selector comparison while cloning a cleanup handler,
1644 // we want to stop cloning immediately. Anything after the dispatch
1645 // will be outlined into a different handler.
1646 BasicBlock *CatchHandler;
1649 if (isSelectorDispatch(const_cast<BasicBlock *>(Inst->getParent()),
1650 CatchHandler, Selector, NextBB)) {
1651 ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
1652 return CloningDirector::StopCloningBB;
1654 // If eg.typeid.for is called for any other reason, it can be ignored.
1655 VMap[Inst] = ConstantInt::get(SelectorIDType, 0);
1656 return CloningDirector::SkipInstruction;
1659 CloningDirector::CloningAction WinEHCleanupDirector::handleInvoke(
1660 ValueToValueMapTy &VMap, const InvokeInst *Invoke, BasicBlock *NewBB) {
1661 // All invokes in cleanup handlers can be replaced with calls.
1662 SmallVector<Value *, 16> CallArgs(Invoke->op_begin(), Invoke->op_end() - 3);
1663 // Insert a normal call instruction...
1665 CallInst::Create(const_cast<Value *>(Invoke->getCalledValue()), CallArgs,
1666 Invoke->getName(), NewBB);
1667 NewCall->setCallingConv(Invoke->getCallingConv());
1668 NewCall->setAttributes(Invoke->getAttributes());
1669 NewCall->setDebugLoc(Invoke->getDebugLoc());
1670 VMap[Invoke] = NewCall;
1672 // Remap the operands.
1673 llvm::RemapInstruction(NewCall, VMap, RF_None, nullptr, &Materializer);
1675 // Insert an unconditional branch to the normal destination.
1676 BranchInst::Create(Invoke->getNormalDest(), NewBB);
1678 // The unwind destination won't be cloned into the new function, so
1679 // we don't need to clean up its phi nodes.
1681 // We just added a terminator to the cloned block.
1682 // Tell the caller to stop processing the current basic block.
1683 return CloningDirector::CloneSuccessors;
1686 CloningDirector::CloningAction WinEHCleanupDirector::handleResume(
1687 ValueToValueMapTy &VMap, const ResumeInst *Resume, BasicBlock *NewBB) {
1688 ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
1690 // We just added a terminator to the cloned block.
1691 // Tell the caller to stop processing the current basic block so that
1692 // the branch instruction will be skipped.
1693 return CloningDirector::StopCloningBB;
1696 CloningDirector::CloningAction
1697 WinEHCleanupDirector::handleCompare(ValueToValueMapTy &VMap,
1698 const CmpInst *Compare, BasicBlock *NewBB) {
1699 if (match(Compare->getOperand(0), m_Intrinsic<Intrinsic::eh_typeid_for>()) ||
1700 match(Compare->getOperand(1), m_Intrinsic<Intrinsic::eh_typeid_for>())) {
1701 VMap[Compare] = ConstantInt::get(SelectorIDType, 1);
1702 return CloningDirector::SkipInstruction;
1704 return CloningDirector::CloneInstruction;
1707 WinEHFrameVariableMaterializer::WinEHFrameVariableMaterializer(
1708 Function *OutlinedFn, Value *ParentFP, FrameVarInfoMap &FrameVarInfo)
1709 : FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) {
1710 BasicBlock *EntryBB = &OutlinedFn->getEntryBlock();
1712 // New allocas should be inserted in the entry block, but after the parent FP
1713 // is established if it is an instruction.
1714 Instruction *InsertPoint = EntryBB->getFirstInsertionPt();
1715 if (auto *FPInst = dyn_cast<Instruction>(ParentFP))
1716 InsertPoint = FPInst->getNextNode();
1717 Builder.SetInsertPoint(EntryBB, InsertPoint);
1720 Value *WinEHFrameVariableMaterializer::materializeValueFor(Value *V) {
1721 // If we're asked to materialize a static alloca, we temporarily create an
1722 // alloca in the outlined function and add this to the FrameVarInfo map. When
1723 // all the outlining is complete, we'll replace these temporary allocas with
1724 // calls to llvm.framerecover.
1725 if (auto *AV = dyn_cast<AllocaInst>(V)) {
1726 assert(AV->isStaticAlloca() &&
1727 "cannot materialize un-demoted dynamic alloca");
1728 AllocaInst *NewAlloca = dyn_cast<AllocaInst>(AV->clone());
1729 Builder.Insert(NewAlloca, AV->getName());
1730 FrameVarInfo[AV].push_back(NewAlloca);
1734 if (isa<Instruction>(V) || isa<Argument>(V)) {
1735 Function *Parent = isa<Instruction>(V)
1736 ? cast<Instruction>(V)->getParent()->getParent()
1737 : cast<Argument>(V)->getParent();
1739 << "Failed to demote instruction used in exception handler of function "
1740 << GlobalValue::getRealLinkageName(Parent->getName()) << ":\n";
1741 errs() << " " << *V << '\n';
1742 report_fatal_error("WinEHPrepare failed to demote instruction");
1745 // Don't materialize other values.
1749 void WinEHFrameVariableMaterializer::escapeCatchObject(Value *V) {
1750 // Catch parameter objects have to live in the parent frame. When we see a use
1751 // of a catch parameter, add a sentinel to the multimap to indicate that it's
1752 // used from another handler. This will prevent us from trying to sink the
1753 // alloca into the handler and ensure that the catch parameter is present in
1754 // the call to llvm.frameescape.
1755 FrameVarInfo[V].push_back(getCatchObjectSentinel());
1758 // This function maps the catch and cleanup handlers that are reachable from the
1759 // specified landing pad. The landing pad sequence will have this basic shape:
1761 // <cleanup handler>
1762 // <selector comparison>
1764 // <cleanup handler>
1765 // <selector comparison>
1767 // <cleanup handler>
1770 // Any of the cleanup slots may be absent. The cleanup slots may be occupied by
1771 // any arbitrary control flow, but all paths through the cleanup code must
1772 // eventually reach the next selector comparison and no path can skip to a
1773 // different selector comparisons, though some paths may terminate abnormally.
1774 // Therefore, we will use a depth first search from the start of any given
1775 // cleanup block and stop searching when we find the next selector comparison.
1777 // If the landingpad instruction does not have a catch clause, we will assume
1778 // that any instructions other than selector comparisons and catch handlers can
1779 // be ignored. In practice, these will only be the boilerplate instructions.
1781 // The catch handlers may also have any control structure, but we are only
1782 // interested in the start of the catch handlers, so we don't need to actually
1783 // follow the flow of the catch handlers. The start of the catch handlers can
1784 // be located from the compare instructions, but they can be skipped in the
1785 // flow by following the contrary branch.
1786 void WinEHPrepare::mapLandingPadBlocks(LandingPadInst *LPad,
1787 LandingPadActions &Actions) {
1788 unsigned int NumClauses = LPad->getNumClauses();
1789 unsigned int HandlersFound = 0;
1790 BasicBlock *BB = LPad->getParent();
1792 DEBUG(dbgs() << "Mapping landing pad: " << BB->getName() << "\n");
1794 if (NumClauses == 0) {
1795 findCleanupHandlers(Actions, BB, nullptr);
1799 VisitedBlockSet VisitedBlocks;
1801 while (HandlersFound != NumClauses) {
1802 BasicBlock *NextBB = nullptr;
1804 // Skip over filter clauses.
1805 if (LPad->isFilter(HandlersFound)) {
1810 // See if the clause we're looking for is a catch-all.
1811 // If so, the catch begins immediately.
1812 Constant *ExpectedSelector =
1813 LPad->getClause(HandlersFound)->stripPointerCasts();
1814 if (isa<ConstantPointerNull>(ExpectedSelector)) {
1815 // The catch all must occur last.
1816 assert(HandlersFound == NumClauses - 1);
1818 // There can be additional selector dispatches in the call chain that we
1820 BasicBlock *CatchBlock = nullptr;
1822 while (BB && isSelectorDispatch(BB, CatchBlock, Selector, NextBB)) {
1823 DEBUG(dbgs() << " Found extra catch dispatch in block "
1824 << CatchBlock->getName() << "\n");
1828 // Add the catch handler to the action list.
1829 CatchHandler *Action = nullptr;
1830 if (CatchHandlerMap.count(BB) && CatchHandlerMap[BB] != nullptr) {
1831 // If the CatchHandlerMap already has an entry for this BB, re-use it.
1832 Action = CatchHandlerMap[BB];
1833 assert(Action->getSelector() == ExpectedSelector);
1835 // We don't expect a selector dispatch, but there may be a call to
1836 // llvm.eh.begincatch, which separates catch handling code from
1837 // cleanup code in the same control flow. This call looks for the
1838 // begincatch intrinsic.
1839 Action = findCatchHandler(BB, NextBB, VisitedBlocks);
1841 // For C++ EH, check if there is any interesting cleanup code before
1842 // we begin the catch. This is important because cleanups cannot
1843 // rethrow exceptions but code called from catches can. For SEH, it
1844 // isn't important if some finally code before a catch-all is executed
1845 // out of line or after recovering from the exception.
1846 if (Personality == EHPersonality::MSVC_CXX)
1847 findCleanupHandlers(Actions, BB, BB);
1849 // If an action was not found, it means that the control flows
1850 // directly into the catch-all handler and there is no cleanup code.
1851 // That's an expected situation and we must create a catch action.
1852 // Since this is a catch-all handler, the selector won't actually
1853 // appear in the code anywhere. ExpectedSelector here is the constant
1854 // null ptr that we got from the landing pad instruction.
1855 Action = new CatchHandler(BB, ExpectedSelector, nullptr);
1856 CatchHandlerMap[BB] = Action;
1859 Actions.insertCatchHandler(Action);
1860 DEBUG(dbgs() << " Catch all handler at block " << BB->getName() << "\n");
1863 // Once we reach a catch-all, don't expect to hit a resume instruction.
1868 CatchHandler *CatchAction = findCatchHandler(BB, NextBB, VisitedBlocks);
1869 assert(CatchAction);
1871 // See if there is any interesting code executed before the dispatch.
1872 findCleanupHandlers(Actions, BB, CatchAction->getStartBlock());
1874 // When the source program contains multiple nested try blocks the catch
1875 // handlers can get strung together in such a way that we can encounter
1876 // a dispatch for a selector that we've already had a handler for.
1877 if (CatchAction->getSelector()->stripPointerCasts() == ExpectedSelector) {
1880 // Add the catch handler to the action list.
1881 DEBUG(dbgs() << " Found catch dispatch in block "
1882 << CatchAction->getStartBlock()->getName() << "\n");
1883 Actions.insertCatchHandler(CatchAction);
1885 // Under some circumstances optimized IR will flow unconditionally into a
1886 // handler block without checking the selector. This can only happen if
1887 // the landing pad has a catch-all handler and the handler for the
1888 // preceeding catch clause is identical to the catch-call handler
1889 // (typically an empty catch). In this case, the handler must be shared
1890 // by all remaining clauses.
1891 if (isa<ConstantPointerNull>(
1892 CatchAction->getSelector()->stripPointerCasts())) {
1893 DEBUG(dbgs() << " Applying early catch-all handler in block "
1894 << CatchAction->getStartBlock()->getName()
1895 << " to all remaining clauses.\n");
1896 Actions.insertCatchHandler(CatchAction);
1900 DEBUG(dbgs() << " Found extra catch dispatch in block "
1901 << CatchAction->getStartBlock()->getName() << "\n");
1904 // Move on to the block after the catch handler.
1908 // If we didn't wind up in a catch-all, see if there is any interesting code
1909 // executed before the resume.
1910 findCleanupHandlers(Actions, BB, BB);
1912 // It's possible that some optimization moved code into a landingpad that
1914 // previously being used for cleanup. If that happens, we need to execute
1916 // extra code from a cleanup handler.
1917 if (Actions.includesCleanup() && !LPad->isCleanup())
1918 LPad->setCleanup(true);
1921 // This function searches starting with the input block for the next
1922 // block that terminates with a branch whose condition is based on a selector
1923 // comparison. This may be the input block. See the mapLandingPadBlocks
1924 // comments for a discussion of control flow assumptions.
1926 CatchHandler *WinEHPrepare::findCatchHandler(BasicBlock *BB,
1927 BasicBlock *&NextBB,
1928 VisitedBlockSet &VisitedBlocks) {
1929 // See if we've already found a catch handler use it.
1930 // Call count() first to avoid creating a null entry for blocks
1931 // we haven't seen before.
1932 if (CatchHandlerMap.count(BB) && CatchHandlerMap[BB] != nullptr) {
1933 CatchHandler *Action = cast<CatchHandler>(CatchHandlerMap[BB]);
1934 NextBB = Action->getNextBB();
1938 // VisitedBlocks applies only to the current search. We still
1939 // need to consider blocks that we've visited while mapping other
1941 VisitedBlocks.insert(BB);
1943 BasicBlock *CatchBlock = nullptr;
1944 Constant *Selector = nullptr;
1946 // If this is the first time we've visited this block from any landing pad
1947 // look to see if it is a selector dispatch block.
1948 if (!CatchHandlerMap.count(BB)) {
1949 if (isSelectorDispatch(BB, CatchBlock, Selector, NextBB)) {
1950 CatchHandler *Action = new CatchHandler(BB, Selector, NextBB);
1951 CatchHandlerMap[BB] = Action;
1954 // If we encounter a block containing an llvm.eh.begincatch before we
1955 // find a selector dispatch block, the handler is assumed to be
1956 // reached unconditionally. This happens for catch-all blocks, but
1957 // it can also happen for other catch handlers that have been combined
1958 // with the catch-all handler during optimization.
1959 if (isCatchBlock(BB)) {
1960 PointerType *Int8PtrTy = Type::getInt8PtrTy(BB->getContext());
1961 Constant *NullSelector = ConstantPointerNull::get(Int8PtrTy);
1962 CatchHandler *Action = new CatchHandler(BB, NullSelector, nullptr);
1963 CatchHandlerMap[BB] = Action;
1968 // Visit each successor, looking for the dispatch.
1969 // FIXME: We expect to find the dispatch quickly, so this will probably
1970 // work better as a breadth first search.
1971 for (BasicBlock *Succ : successors(BB)) {
1972 if (VisitedBlocks.count(Succ))
1975 CatchHandler *Action = findCatchHandler(Succ, NextBB, VisitedBlocks);
1982 // These are helper functions to combine repeated code from findCleanupHandlers.
1983 static void createCleanupHandler(LandingPadActions &Actions,
1984 CleanupHandlerMapTy &CleanupHandlerMap,
1986 CleanupHandler *Action = new CleanupHandler(BB);
1987 CleanupHandlerMap[BB] = Action;
1988 Actions.insertCleanupHandler(Action);
1989 DEBUG(dbgs() << " Found cleanup code in block "
1990 << Action->getStartBlock()->getName() << "\n");
1993 static CallSite matchOutlinedFinallyCall(BasicBlock *BB,
1994 Instruction *MaybeCall) {
1995 // Look for finally blocks that Clang has already outlined for us.
1996 // %fp = call i8* @llvm.frameaddress(i32 0)
1997 // call void @"fin$parent"(iN 1, i8* %fp)
1998 if (isFrameAddressCall(MaybeCall) && MaybeCall != BB->getTerminator())
1999 MaybeCall = MaybeCall->getNextNode();
2000 CallSite FinallyCall(MaybeCall);
2001 if (!FinallyCall || FinallyCall.arg_size() != 2)
2003 if (!match(FinallyCall.getArgument(0), m_SpecificInt(1)))
2005 if (!isFrameAddressCall(FinallyCall.getArgument(1)))
2010 static BasicBlock *followSingleUnconditionalBranches(BasicBlock *BB) {
2011 // Skip single ubr blocks.
2012 while (BB->getFirstNonPHIOrDbg() == BB->getTerminator()) {
2013 auto *Br = dyn_cast<BranchInst>(BB->getTerminator());
2014 if (Br && Br->isUnconditional())
2015 BB = Br->getSuccessor(0);
2022 // This function searches starting with the input block for the next block that
2023 // contains code that is not part of a catch handler and would not be eliminated
2024 // during handler outlining.
2026 void WinEHPrepare::findCleanupHandlers(LandingPadActions &Actions,
2027 BasicBlock *StartBB, BasicBlock *EndBB) {
2028 // Here we will skip over the following:
2030 // landing pad prolog:
2032 // Unconditional branches
2034 // Selector dispatch
2038 // Anything else marks the start of an interesting block
2040 BasicBlock *BB = StartBB;
2041 // Anything other than an unconditional branch will kick us out of this loop
2042 // one way or another.
2044 BB = followSingleUnconditionalBranches(BB);
2045 // If we've already scanned this block, don't scan it again. If it is
2046 // a cleanup block, there will be an action in the CleanupHandlerMap.
2047 // If we've scanned it and it is not a cleanup block, there will be a
2048 // nullptr in the CleanupHandlerMap. If we have not scanned it, there will
2049 // be no entry in the CleanupHandlerMap. We must call count() first to
2050 // avoid creating a null entry for blocks we haven't scanned.
2051 if (CleanupHandlerMap.count(BB)) {
2052 if (auto *Action = CleanupHandlerMap[BB]) {
2053 Actions.insertCleanupHandler(Action);
2054 DEBUG(dbgs() << " Found cleanup code in block "
2055 << Action->getStartBlock()->getName() << "\n");
2056 // FIXME: This cleanup might chain into another, and we need to discover
2060 // Here we handle the case where the cleanup handler map contains a
2061 // value for this block but the value is a nullptr. This means that
2062 // we have previously analyzed the block and determined that it did
2063 // not contain any cleanup code. Based on the earlier analysis, we
2064 // know the the block must end in either an unconditional branch, a
2065 // resume or a conditional branch that is predicated on a comparison
2066 // with a selector. Either the resume or the selector dispatch
2067 // would terminate the search for cleanup code, so the unconditional
2068 // branch is the only case for which we might need to continue
2070 BasicBlock *SuccBB = followSingleUnconditionalBranches(BB);
2071 if (SuccBB == BB || SuccBB == EndBB)
2078 // Create an entry in the cleanup handler map for this block. Initially
2079 // we create an entry that says this isn't a cleanup block. If we find
2080 // cleanup code, the caller will replace this entry.
2081 CleanupHandlerMap[BB] = nullptr;
2083 TerminatorInst *Terminator = BB->getTerminator();
2085 // Landing pad blocks have extra instructions we need to accept.
2086 LandingPadMap *LPadMap = nullptr;
2087 if (BB->isLandingPad()) {
2088 LandingPadInst *LPad = BB->getLandingPadInst();
2089 LPadMap = &LPadMaps[LPad];
2090 if (!LPadMap->isInitialized())
2091 LPadMap->mapLandingPad(LPad);
2094 // Look for the bare resume pattern:
2095 // %lpad.val1 = insertvalue { i8*, i32 } undef, i8* %exn, 0
2096 // %lpad.val2 = insertvalue { i8*, i32 } %lpad.val1, i32 %sel, 1
2097 // resume { i8*, i32 } %lpad.val2
2098 if (auto *Resume = dyn_cast<ResumeInst>(Terminator)) {
2099 InsertValueInst *Insert1 = nullptr;
2100 InsertValueInst *Insert2 = nullptr;
2101 Value *ResumeVal = Resume->getOperand(0);
2102 // If the resume value isn't a phi or landingpad value, it should be a
2103 // series of insertions. Identify them so we can avoid them when scanning
2105 if (!isa<PHINode>(ResumeVal) && !isa<LandingPadInst>(ResumeVal)) {
2106 Insert2 = dyn_cast<InsertValueInst>(ResumeVal);
2108 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2109 Insert1 = dyn_cast<InsertValueInst>(Insert2->getAggregateOperand());
2111 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2113 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
2115 Instruction *Inst = II;
2116 if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
2118 if (Inst == Insert1 || Inst == Insert2 || Inst == Resume)
2120 if (!Inst->hasOneUse() ||
2121 (Inst->user_back() != Insert1 && Inst->user_back() != Insert2)) {
2122 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2128 BranchInst *Branch = dyn_cast<BranchInst>(Terminator);
2129 if (Branch && Branch->isConditional()) {
2130 // Look for the selector dispatch.
2131 // %2 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIf to i8*))
2132 // %matches = icmp eq i32 %sel, %2
2133 // br i1 %matches, label %catch14, label %eh.resume
2134 CmpInst *Compare = dyn_cast<CmpInst>(Branch->getCondition());
2135 if (!Compare || !Compare->isEquality())
2136 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2137 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
2139 Instruction *Inst = II;
2140 if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
2142 if (Inst == Compare || Inst == Branch)
2144 if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
2146 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2148 // The selector dispatch block should always terminate our search.
2149 assert(BB == EndBB);
2153 if (isAsynchronousEHPersonality(Personality)) {
2154 // If this is a landingpad block, split the block at the first non-landing
2156 Instruction *MaybeCall = BB->getFirstNonPHIOrDbg();
2158 while (MaybeCall != BB->getTerminator() &&
2159 LPadMap->isLandingPadSpecificInst(MaybeCall))
2160 MaybeCall = MaybeCall->getNextNode();
2163 // Look for outlined finally calls.
2164 if (CallSite FinallyCall = matchOutlinedFinallyCall(BB, MaybeCall)) {
2165 Function *Fin = FinallyCall.getCalledFunction();
2166 assert(Fin && "outlined finally call should be direct");
2167 auto *Action = new CleanupHandler(BB);
2168 Action->setHandlerBlockOrFunc(Fin);
2169 Actions.insertCleanupHandler(Action);
2170 CleanupHandlerMap[BB] = Action;
2171 DEBUG(dbgs() << " Found frontend-outlined finally call to "
2172 << Fin->getName() << " in block "
2173 << Action->getStartBlock()->getName() << "\n");
2175 // Split the block if there were more interesting instructions and look
2176 // for finally calls in the normal successor block.
2177 BasicBlock *SuccBB = BB;
2178 if (FinallyCall.getInstruction() != BB->getTerminator() &&
2179 FinallyCall.getInstruction()->getNextNode() !=
2180 BB->getTerminator()) {
2182 SplitBlock(BB, FinallyCall.getInstruction()->getNextNode(), DT);
2184 if (FinallyCall.isInvoke()) {
2186 cast<InvokeInst>(FinallyCall.getInstruction())->getNormalDest();
2188 SuccBB = BB->getUniqueSuccessor();
2190 "splitOutlinedFinallyCalls didn't insert a branch");
2200 // Anything else is either a catch block or interesting cleanup code.
2201 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
2203 Instruction *Inst = II;
2204 if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
2206 // Unconditional branches fall through to this loop.
2209 // If this is a catch block, there is no cleanup code to be found.
2210 if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>()))
2212 // If this a nested landing pad, it may contain an endcatch call.
2213 if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
2215 // Anything else makes this interesting cleanup code.
2216 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2219 // Only unconditional branches in empty blocks should get this far.
2220 assert(Branch && Branch->isUnconditional());
2223 BB = Branch->getSuccessor(0);
2227 // This is a public function, declared in WinEHFuncInfo.h and is also
2228 // referenced by WinEHNumbering in FunctionLoweringInfo.cpp.
2229 void llvm::parseEHActions(const IntrinsicInst *II,
2230 SmallVectorImpl<ActionHandler *> &Actions) {
2231 for (unsigned I = 0, E = II->getNumArgOperands(); I != E;) {
2232 uint64_t ActionKind =
2233 cast<ConstantInt>(II->getArgOperand(I))->getZExtValue();
2234 if (ActionKind == /*catch=*/1) {
2235 auto *Selector = cast<Constant>(II->getArgOperand(I + 1));
2236 ConstantInt *EHObjIndex = cast<ConstantInt>(II->getArgOperand(I + 2));
2237 int64_t EHObjIndexVal = EHObjIndex->getSExtValue();
2238 Constant *Handler = cast<Constant>(II->getArgOperand(I + 3));
2240 auto *CH = new CatchHandler(/*BB=*/nullptr, Selector, /*NextBB=*/nullptr);
2241 CH->setHandlerBlockOrFunc(Handler);
2242 CH->setExceptionVarIndex(EHObjIndexVal);
2243 Actions.push_back(CH);
2244 } else if (ActionKind == 0) {
2245 Constant *Handler = cast<Constant>(II->getArgOperand(I + 1));
2247 auto *CH = new CleanupHandler(/*BB=*/nullptr);
2248 CH->setHandlerBlockOrFunc(Handler);
2249 Actions.push_back(CH);
2251 llvm_unreachable("Expected either a catch or cleanup handler!");
2254 std::reverse(Actions.begin(), Actions.end());