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/SetVector.h"
22 #include "llvm/ADT/Triple.h"
23 #include "llvm/ADT/TinyPtrVector.h"
24 #include "llvm/Analysis/LibCallSemantics.h"
25 #include "llvm/CodeGen/WinEHFuncInfo.h"
26 #include "llvm/IR/Dominators.h"
27 #include "llvm/IR/Function.h"
28 #include "llvm/IR/IRBuilder.h"
29 #include "llvm/IR/Instructions.h"
30 #include "llvm/IR/IntrinsicInst.h"
31 #include "llvm/IR/Module.h"
32 #include "llvm/IR/PatternMatch.h"
33 #include "llvm/Pass.h"
34 #include "llvm/Support/CommandLine.h"
35 #include "llvm/Support/Debug.h"
36 #include "llvm/Support/raw_ostream.h"
37 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
38 #include "llvm/Transforms/Utils/Cloning.h"
39 #include "llvm/Transforms/Utils/Local.h"
40 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
44 using namespace llvm::PatternMatch;
46 #define DEBUG_TYPE "winehprepare"
50 // This map is used to model frame variable usage during outlining, to
51 // construct a structure type to hold the frame variables in a frame
52 // allocation block, and to remap the frame variable allocas (including
53 // spill locations as needed) to GEPs that get the variable from the
54 // frame allocation structure.
55 typedef MapVector<Value *, TinyPtrVector<AllocaInst *>> FrameVarInfoMap;
57 // TinyPtrVector cannot hold nullptr, so we need our own sentinel that isn't
59 AllocaInst *getCatchObjectSentinel() {
60 return static_cast<AllocaInst *>(nullptr) + 1;
63 typedef SmallSet<BasicBlock *, 4> VisitedBlockSet;
65 class LandingPadActions;
68 typedef DenseMap<const BasicBlock *, CatchHandler *> CatchHandlerMapTy;
69 typedef DenseMap<const BasicBlock *, CleanupHandler *> CleanupHandlerMapTy;
71 class WinEHPrepare : public FunctionPass {
73 static char ID; // Pass identification, replacement for typeid.
74 WinEHPrepare(const TargetMachine *TM = nullptr)
77 TheTriple = Triple(TM->getTargetTriple());
80 bool runOnFunction(Function &Fn) override;
82 bool doFinalization(Module &M) override;
84 void getAnalysisUsage(AnalysisUsage &AU) const override;
86 const char *getPassName() const override {
87 return "Windows exception handling preparation";
91 bool prepareExceptionHandlers(Function &F,
92 SmallVectorImpl<LandingPadInst *> &LPads);
93 void promoteLandingPadValues(LandingPadInst *LPad);
94 void demoteValuesLiveAcrossHandlers(Function &F,
95 SmallVectorImpl<LandingPadInst *> &LPads);
96 void findSEHEHReturnPoints(Function &F,
97 SetVector<BasicBlock *> &EHReturnBlocks);
98 void findCXXEHReturnPoints(Function &F,
99 SetVector<BasicBlock *> &EHReturnBlocks);
100 void completeNestedLandingPad(Function *ParentFn,
101 LandingPadInst *OutlinedLPad,
102 const LandingPadInst *OriginalLPad,
103 FrameVarInfoMap &VarInfo);
104 Function *createHandlerFunc(Type *RetTy, const Twine &Name, Module *M,
106 bool outlineHandler(ActionHandler *Action, Function *SrcFn,
107 LandingPadInst *LPad, BasicBlock *StartBB,
108 FrameVarInfoMap &VarInfo);
109 void addStubInvokeToHandlerIfNeeded(Function *Handler, Value *PersonalityFn);
111 void mapLandingPadBlocks(LandingPadInst *LPad, LandingPadActions &Actions);
112 CatchHandler *findCatchHandler(BasicBlock *BB, BasicBlock *&NextBB,
113 VisitedBlockSet &VisitedBlocks);
114 void findCleanupHandlers(LandingPadActions &Actions, BasicBlock *StartBB,
117 void processSEHCatchHandler(CatchHandler *Handler, BasicBlock *StartBB);
121 // All fields are reset by runOnFunction.
122 DominatorTree *DT = nullptr;
123 EHPersonality Personality = EHPersonality::Unknown;
124 CatchHandlerMapTy CatchHandlerMap;
125 CleanupHandlerMapTy CleanupHandlerMap;
126 DenseMap<const LandingPadInst *, LandingPadMap> LPadMaps;
128 // This maps landing pad instructions found in outlined handlers to
129 // the landing pad instruction in the parent function from which they
130 // were cloned. The cloned/nested landing pad is used as the key
131 // because the landing pad may be cloned into multiple handlers.
132 // This map will be used to add the llvm.eh.actions call to the nested
133 // landing pads after all handlers have been outlined.
134 DenseMap<LandingPadInst *, const LandingPadInst *> NestedLPtoOriginalLP;
136 // This maps blocks in the parent function which are destinations of
137 // catch handlers to cloned blocks in (other) outlined handlers. This
138 // handles the case where a nested landing pads has a catch handler that
139 // returns to a handler function rather than the parent function.
140 // The original block is used as the key here because there should only
141 // ever be one handler function from which the cloned block is not pruned.
142 // The original block will be pruned from the parent function after all
143 // handlers have been outlined. This map will be used to adjust the
144 // return instructions of handlers which return to the block that was
145 // outlined into a handler. This is done after all handlers have been
146 // outlined but before the outlined code is pruned from the parent function.
147 DenseMap<const BasicBlock *, BasicBlock *> LPadTargetBlocks;
149 // Map from outlined handler to call to llvm.frameaddress(1). Only used for
151 DenseMap<Function *, Value *> HandlerToParentFP;
153 AllocaInst *SEHExceptionCodeSlot = nullptr;
156 class WinEHFrameVariableMaterializer : public ValueMaterializer {
158 WinEHFrameVariableMaterializer(Function *OutlinedFn, Value *ParentFP,
159 FrameVarInfoMap &FrameVarInfo);
160 ~WinEHFrameVariableMaterializer() override {}
162 Value *materializeValueFor(Value *V) override;
164 void escapeCatchObject(Value *V);
167 FrameVarInfoMap &FrameVarInfo;
171 class LandingPadMap {
173 LandingPadMap() : OriginLPad(nullptr) {}
174 void mapLandingPad(const LandingPadInst *LPad);
176 bool isInitialized() { return OriginLPad != nullptr; }
178 bool isOriginLandingPadBlock(const BasicBlock *BB) const;
179 bool isLandingPadSpecificInst(const Instruction *Inst) const;
181 void remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
182 Value *SelectorValue) const;
185 const LandingPadInst *OriginLPad;
186 // We will normally only see one of each of these instructions, but
187 // if more than one occurs for some reason we can handle that.
188 TinyPtrVector<const ExtractValueInst *> ExtractedEHPtrs;
189 TinyPtrVector<const ExtractValueInst *> ExtractedSelectors;
192 class WinEHCloningDirectorBase : public CloningDirector {
194 WinEHCloningDirectorBase(Function *HandlerFn, Value *ParentFP,
195 FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
196 : Materializer(HandlerFn, ParentFP, VarInfo),
197 SelectorIDType(Type::getInt32Ty(HandlerFn->getContext())),
198 Int8PtrType(Type::getInt8PtrTy(HandlerFn->getContext())),
199 LPadMap(LPadMap), ParentFP(ParentFP) {}
201 CloningAction handleInstruction(ValueToValueMapTy &VMap,
202 const Instruction *Inst,
203 BasicBlock *NewBB) override;
205 virtual CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
206 const Instruction *Inst,
207 BasicBlock *NewBB) = 0;
208 virtual CloningAction handleEndCatch(ValueToValueMapTy &VMap,
209 const Instruction *Inst,
210 BasicBlock *NewBB) = 0;
211 virtual CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
212 const Instruction *Inst,
213 BasicBlock *NewBB) = 0;
214 virtual CloningAction handleInvoke(ValueToValueMapTy &VMap,
215 const InvokeInst *Invoke,
216 BasicBlock *NewBB) = 0;
217 virtual CloningAction handleResume(ValueToValueMapTy &VMap,
218 const ResumeInst *Resume,
219 BasicBlock *NewBB) = 0;
220 virtual CloningAction handleCompare(ValueToValueMapTy &VMap,
221 const CmpInst *Compare,
222 BasicBlock *NewBB) = 0;
223 virtual CloningAction handleLandingPad(ValueToValueMapTy &VMap,
224 const LandingPadInst *LPad,
225 BasicBlock *NewBB) = 0;
227 ValueMaterializer *getValueMaterializer() override { return &Materializer; }
230 WinEHFrameVariableMaterializer Materializer;
231 Type *SelectorIDType;
233 LandingPadMap &LPadMap;
235 /// The value representing the parent frame pointer.
239 class WinEHCatchDirector : public WinEHCloningDirectorBase {
242 Function *CatchFn, Value *ParentFP, Value *Selector,
243 FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap,
244 DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPads)
245 : WinEHCloningDirectorBase(CatchFn, ParentFP, VarInfo, LPadMap),
246 CurrentSelector(Selector->stripPointerCasts()),
247 ExceptionObjectVar(nullptr), NestedLPtoOriginalLP(NestedLPads) {}
249 CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
250 const Instruction *Inst,
251 BasicBlock *NewBB) override;
252 CloningAction handleEndCatch(ValueToValueMapTy &VMap, const Instruction *Inst,
253 BasicBlock *NewBB) override;
254 CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
255 const Instruction *Inst,
256 BasicBlock *NewBB) override;
257 CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
258 BasicBlock *NewBB) override;
259 CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
260 BasicBlock *NewBB) override;
261 CloningAction handleCompare(ValueToValueMapTy &VMap, const CmpInst *Compare,
262 BasicBlock *NewBB) override;
263 CloningAction handleLandingPad(ValueToValueMapTy &VMap,
264 const LandingPadInst *LPad,
265 BasicBlock *NewBB) override;
267 Value *getExceptionVar() { return ExceptionObjectVar; }
268 TinyPtrVector<BasicBlock *> &getReturnTargets() { return ReturnTargets; }
271 Value *CurrentSelector;
273 Value *ExceptionObjectVar;
274 TinyPtrVector<BasicBlock *> ReturnTargets;
276 // This will be a reference to the field of the same name in the WinEHPrepare
277 // object which instantiates this WinEHCatchDirector object.
278 DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPtoOriginalLP;
281 class WinEHCleanupDirector : public WinEHCloningDirectorBase {
283 WinEHCleanupDirector(Function *CleanupFn, Value *ParentFP,
284 FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
285 : WinEHCloningDirectorBase(CleanupFn, ParentFP, VarInfo,
288 CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
289 const Instruction *Inst,
290 BasicBlock *NewBB) override;
291 CloningAction handleEndCatch(ValueToValueMapTy &VMap, const Instruction *Inst,
292 BasicBlock *NewBB) override;
293 CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
294 const Instruction *Inst,
295 BasicBlock *NewBB) override;
296 CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
297 BasicBlock *NewBB) override;
298 CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
299 BasicBlock *NewBB) override;
300 CloningAction handleCompare(ValueToValueMapTy &VMap, const CmpInst *Compare,
301 BasicBlock *NewBB) override;
302 CloningAction handleLandingPad(ValueToValueMapTy &VMap,
303 const LandingPadInst *LPad,
304 BasicBlock *NewBB) override;
307 class LandingPadActions {
309 LandingPadActions() : HasCleanupHandlers(false) {}
311 void insertCatchHandler(CatchHandler *Action) { Actions.push_back(Action); }
312 void insertCleanupHandler(CleanupHandler *Action) {
313 Actions.push_back(Action);
314 HasCleanupHandlers = true;
317 bool includesCleanup() const { return HasCleanupHandlers; }
319 SmallVectorImpl<ActionHandler *> &actions() { return Actions; }
320 SmallVectorImpl<ActionHandler *>::iterator begin() { return Actions.begin(); }
321 SmallVectorImpl<ActionHandler *>::iterator end() { return Actions.end(); }
324 // Note that this class does not own the ActionHandler objects in this vector.
325 // The ActionHandlers are owned by the CatchHandlerMap and CleanupHandlerMap
326 // in the WinEHPrepare class.
327 SmallVector<ActionHandler *, 4> Actions;
328 bool HasCleanupHandlers;
331 } // end anonymous namespace
333 char WinEHPrepare::ID = 0;
334 INITIALIZE_TM_PASS(WinEHPrepare, "winehprepare", "Prepare Windows exceptions",
337 FunctionPass *llvm::createWinEHPass(const TargetMachine *TM) {
338 return new WinEHPrepare(TM);
341 bool WinEHPrepare::runOnFunction(Function &Fn) {
342 // No need to prepare outlined handlers.
343 if (Fn.hasFnAttribute("wineh-parent"))
346 SmallVector<LandingPadInst *, 4> LPads;
347 SmallVector<ResumeInst *, 4> Resumes;
348 for (BasicBlock &BB : Fn) {
349 if (auto *LP = BB.getLandingPadInst())
351 if (auto *Resume = dyn_cast<ResumeInst>(BB.getTerminator()))
352 Resumes.push_back(Resume);
355 // No need to prepare functions that lack landing pads.
359 // Classify the personality to see what kind of preparation we need.
360 Personality = classifyEHPersonality(LPads.back()->getPersonalityFn());
362 // Do nothing if this is not an MSVC personality.
363 if (!isMSVCEHPersonality(Personality))
366 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
368 // If there were any landing pads, prepareExceptionHandlers will make changes.
369 prepareExceptionHandlers(Fn, LPads);
373 bool WinEHPrepare::doFinalization(Module &M) { return false; }
375 void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {
376 AU.addRequired<DominatorTreeWrapperPass>();
379 static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler,
380 Constant *&Selector, BasicBlock *&NextBB);
382 // Finds blocks reachable from the starting set Worklist. Does not follow unwind
383 // edges or blocks listed in StopPoints.
384 static void findReachableBlocks(SmallPtrSetImpl<BasicBlock *> &ReachableBBs,
385 SetVector<BasicBlock *> &Worklist,
386 const SetVector<BasicBlock *> *StopPoints) {
387 while (!Worklist.empty()) {
388 BasicBlock *BB = Worklist.pop_back_val();
390 // Don't cross blocks that we should stop at.
391 if (StopPoints && StopPoints->count(BB))
394 if (!ReachableBBs.insert(BB).second)
395 continue; // Already visited.
397 // Don't follow unwind edges of invokes.
398 if (auto *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
399 Worklist.insert(II->getNormalDest());
403 // Otherwise, follow all successors.
404 Worklist.insert(succ_begin(BB), succ_end(BB));
408 // Attempt to find an instruction where a block can be split before
409 // a call to llvm.eh.begincatch and its operands. If the block
410 // begins with the begincatch call or one of its adjacent operands
411 // the block will not be split.
412 static Instruction *findBeginCatchSplitPoint(BasicBlock *BB,
414 // If the begincatch call is already the first instruction in the block,
416 Instruction *FirstNonPHI = BB->getFirstNonPHI();
417 if (II == FirstNonPHI)
420 // If either operand is in the same basic block as the instruction and
421 // isn't used by another instruction before the begincatch call, include it
422 // in the split block.
423 auto *Op0 = dyn_cast<Instruction>(II->getOperand(0));
424 auto *Op1 = dyn_cast<Instruction>(II->getOperand(1));
426 Instruction *I = II->getPrevNode();
427 Instruction *LastI = II;
429 while (I == Op0 || I == Op1) {
430 // If the block begins with one of the operands and there are no other
431 // instructions between the operand and the begincatch call, don't split.
432 if (I == FirstNonPHI)
436 I = I->getPrevNode();
439 // If there is at least one instruction in the block before the begincatch
440 // call and its operands, split the block at either the begincatch or
445 /// Find all points where exceptional control rejoins normal control flow via
446 /// llvm.eh.endcatch. Add them to the normal bb reachability worklist.
447 void WinEHPrepare::findCXXEHReturnPoints(
448 Function &F, SetVector<BasicBlock *> &EHReturnBlocks) {
449 for (auto BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) {
450 BasicBlock *BB = BBI;
451 for (Instruction &I : *BB) {
452 if (match(&I, m_Intrinsic<Intrinsic::eh_begincatch>())) {
453 Instruction *SplitPt =
454 findBeginCatchSplitPoint(BB, cast<IntrinsicInst>(&I));
456 // Split the block before the llvm.eh.begincatch call to allow
457 // cleanup and catch code to be distinguished later.
458 // Do not update BBI because we still need to process the
459 // portion of the block that we are splitting off.
460 SplitBlock(BB, SplitPt, DT);
464 if (match(&I, m_Intrinsic<Intrinsic::eh_endcatch>())) {
465 // Split the block after the call to llvm.eh.endcatch if there is
466 // anything other than an unconditional branch, or if the successor
467 // starts with a phi.
468 auto *Br = dyn_cast<BranchInst>(I.getNextNode());
469 if (!Br || !Br->isUnconditional() ||
470 isa<PHINode>(Br->getSuccessor(0)->begin())) {
471 DEBUG(dbgs() << "splitting block " << BB->getName()
472 << " with llvm.eh.endcatch\n");
473 BBI = SplitBlock(BB, I.getNextNode(), DT);
475 // The next BB is normal control flow.
476 EHReturnBlocks.insert(BB->getTerminator()->getSuccessor(0));
483 static bool isCatchAllLandingPad(const BasicBlock *BB) {
484 const LandingPadInst *LP = BB->getLandingPadInst();
487 unsigned N = LP->getNumClauses();
488 return (N > 0 && LP->isCatch(N - 1) &&
489 isa<ConstantPointerNull>(LP->getClause(N - 1)));
492 /// Find all points where exceptions control rejoins normal control flow via
493 /// selector dispatch.
494 void WinEHPrepare::findSEHEHReturnPoints(
495 Function &F, SetVector<BasicBlock *> &EHReturnBlocks) {
496 for (auto BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) {
497 BasicBlock *BB = BBI;
498 // If the landingpad is a catch-all, treat the whole lpad as if it is
499 // reachable from normal control flow.
500 // FIXME: This is imprecise. We need a better way of identifying where a
501 // catch-all starts and cleanups stop. As far as LLVM is concerned, there
503 if (isCatchAllLandingPad(BB)) {
504 EHReturnBlocks.insert(BB);
508 BasicBlock *CatchHandler;
511 if (isSelectorDispatch(BB, CatchHandler, Selector, NextBB)) {
512 // Split the edge if there is a phi node. Returning from EH to a phi node
513 // is just as impossible as having a phi after an indirectbr.
514 if (isa<PHINode>(CatchHandler->begin())) {
515 DEBUG(dbgs() << "splitting EH return edge from " << BB->getName()
516 << " to " << CatchHandler->getName() << '\n');
517 BBI = CatchHandler = SplitCriticalEdge(
518 BB, std::find(succ_begin(BB), succ_end(BB), CatchHandler));
520 EHReturnBlocks.insert(CatchHandler);
525 /// Ensure that all values live into and out of exception handlers are stored
527 /// FIXME: This falls down when values are defined in one handler and live into
528 /// another handler. For example, a cleanup defines a value used only by a
530 void WinEHPrepare::demoteValuesLiveAcrossHandlers(
531 Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
532 DEBUG(dbgs() << "Demoting values live across exception handlers in function "
533 << F.getName() << '\n');
535 // Build a set of all non-exceptional blocks and exceptional blocks.
536 // - Non-exceptional blocks are blocks reachable from the entry block while
537 // not following invoke unwind edges.
538 // - Exceptional blocks are blocks reachable from landingpads. Analysis does
539 // not follow llvm.eh.endcatch blocks, which mark a transition from
540 // exceptional to normal control.
541 SmallPtrSet<BasicBlock *, 4> NormalBlocks;
542 SmallPtrSet<BasicBlock *, 4> EHBlocks;
543 SetVector<BasicBlock *> EHReturnBlocks;
544 SetVector<BasicBlock *> Worklist;
546 if (Personality == EHPersonality::MSVC_CXX)
547 findCXXEHReturnPoints(F, EHReturnBlocks);
549 findSEHEHReturnPoints(F, EHReturnBlocks);
552 dbgs() << "identified the following blocks as EH return points:\n";
553 for (BasicBlock *BB : EHReturnBlocks)
554 dbgs() << " " << BB->getName() << '\n';
557 // Join points should not have phis at this point, unless they are a
558 // landingpad, in which case we will demote their phis later.
560 for (BasicBlock *BB : EHReturnBlocks)
561 assert((BB->isLandingPad() || !isa<PHINode>(BB->begin())) &&
562 "non-lpad EH return block has phi");
565 // Normal blocks are the blocks reachable from the entry block and all EH
567 Worklist = EHReturnBlocks;
568 Worklist.insert(&F.getEntryBlock());
569 findReachableBlocks(NormalBlocks, Worklist, nullptr);
571 dbgs() << "marked the following blocks as normal:\n";
572 for (BasicBlock *BB : NormalBlocks)
573 dbgs() << " " << BB->getName() << '\n';
576 // Exceptional blocks are the blocks reachable from landingpads that don't
577 // cross EH return points.
579 for (auto *LPI : LPads)
580 Worklist.insert(LPI->getParent());
581 findReachableBlocks(EHBlocks, Worklist, &EHReturnBlocks);
583 dbgs() << "marked the following blocks as exceptional:\n";
584 for (BasicBlock *BB : EHBlocks)
585 dbgs() << " " << BB->getName() << '\n';
588 SetVector<Argument *> ArgsToDemote;
589 SetVector<Instruction *> InstrsToDemote;
590 for (BasicBlock &BB : F) {
591 bool IsNormalBB = NormalBlocks.count(&BB);
592 bool IsEHBB = EHBlocks.count(&BB);
593 if (!IsNormalBB && !IsEHBB)
594 continue; // Blocks that are neither normal nor EH are unreachable.
595 for (Instruction &I : BB) {
596 for (Value *Op : I.operands()) {
597 // Don't demote static allocas, constants, and labels.
598 if (isa<Constant>(Op) || isa<BasicBlock>(Op) || isa<InlineAsm>(Op))
600 auto *AI = dyn_cast<AllocaInst>(Op);
601 if (AI && AI->isStaticAlloca())
604 if (auto *Arg = dyn_cast<Argument>(Op)) {
606 DEBUG(dbgs() << "Demoting argument " << *Arg
607 << " used by EH instr: " << I << "\n");
608 ArgsToDemote.insert(Arg);
613 auto *OpI = cast<Instruction>(Op);
614 BasicBlock *OpBB = OpI->getParent();
615 // If a value is produced and consumed in the same BB, we don't need to
619 bool IsOpNormalBB = NormalBlocks.count(OpBB);
620 bool IsOpEHBB = EHBlocks.count(OpBB);
621 if (IsNormalBB != IsOpNormalBB || IsEHBB != IsOpEHBB) {
623 dbgs() << "Demoting instruction live in-out from EH:\n";
624 dbgs() << "Instr: " << *OpI << '\n';
625 dbgs() << "User: " << I << '\n';
627 InstrsToDemote.insert(OpI);
633 // Demote values live into and out of handlers.
634 // FIXME: This demotion is inefficient. We should insert spills at the point
635 // of definition, insert one reload in each handler that uses the value, and
636 // insert reloads in the BB used to rejoin normal control flow.
637 Instruction *AllocaInsertPt = F.getEntryBlock().getFirstInsertionPt();
638 for (Instruction *I : InstrsToDemote)
639 DemoteRegToStack(*I, false, AllocaInsertPt);
641 // Demote arguments separately, and only for uses in EH blocks.
642 for (Argument *Arg : ArgsToDemote) {
643 auto *Slot = new AllocaInst(Arg->getType(), nullptr,
644 Arg->getName() + ".reg2mem", AllocaInsertPt);
645 SmallVector<User *, 4> Users(Arg->user_begin(), Arg->user_end());
646 for (User *U : Users) {
647 auto *I = dyn_cast<Instruction>(U);
648 if (I && EHBlocks.count(I->getParent())) {
649 auto *Reload = new LoadInst(Slot, Arg->getName() + ".reload", false, I);
650 U->replaceUsesOfWith(Arg, Reload);
653 new StoreInst(Arg, Slot, AllocaInsertPt);
656 // Demote landingpad phis, as the landingpad will be removed from the machine
658 for (LandingPadInst *LPI : LPads) {
659 BasicBlock *BB = LPI->getParent();
660 while (auto *Phi = dyn_cast<PHINode>(BB->begin()))
661 DemotePHIToStack(Phi, AllocaInsertPt);
664 DEBUG(dbgs() << "Demoted " << InstrsToDemote.size() << " instructions and "
665 << ArgsToDemote.size() << " arguments for WinEHPrepare\n\n");
668 bool WinEHPrepare::prepareExceptionHandlers(
669 Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
670 // Don't run on functions that are already prepared.
671 for (LandingPadInst *LPad : LPads) {
672 BasicBlock *LPadBB = LPad->getParent();
673 for (Instruction &Inst : *LPadBB)
674 if (match(&Inst, m_Intrinsic<Intrinsic::eh_actions>()))
678 demoteValuesLiveAcrossHandlers(F, LPads);
680 // These containers are used to re-map frame variables that are used in
681 // outlined catch and cleanup handlers. They will be populated as the
682 // handlers are outlined.
683 FrameVarInfoMap FrameVarInfo;
685 bool HandlersOutlined = false;
687 Module *M = F.getParent();
688 LLVMContext &Context = M->getContext();
690 // Create a new function to receive the handler contents.
691 PointerType *Int8PtrType = Type::getInt8PtrTy(Context);
692 Type *Int32Type = Type::getInt32Ty(Context);
693 Function *ActionIntrin = Intrinsic::getDeclaration(M, Intrinsic::eh_actions);
695 if (isAsynchronousEHPersonality(Personality)) {
696 // FIXME: Switch the ehptr type to i32 and then switch this.
697 SEHExceptionCodeSlot =
698 new AllocaInst(Int8PtrType, nullptr, "seh_exception_code",
699 F.getEntryBlock().getFirstInsertionPt());
702 for (LandingPadInst *LPad : LPads) {
703 // Look for evidence that this landingpad has already been processed.
704 bool LPadHasActionList = false;
705 BasicBlock *LPadBB = LPad->getParent();
706 for (Instruction &Inst : *LPadBB) {
707 if (match(&Inst, m_Intrinsic<Intrinsic::eh_actions>())) {
708 LPadHasActionList = true;
713 // If we've already outlined the handlers for this landingpad,
714 // there's nothing more to do here.
715 if (LPadHasActionList)
718 // If either of the values in the aggregate returned by the landing pad is
719 // extracted and stored to memory, promote the stored value to a register.
720 promoteLandingPadValues(LPad);
722 LandingPadActions Actions;
723 mapLandingPadBlocks(LPad, Actions);
725 HandlersOutlined |= !Actions.actions().empty();
726 for (ActionHandler *Action : Actions) {
727 if (Action->hasBeenProcessed())
729 BasicBlock *StartBB = Action->getStartBlock();
731 // SEH doesn't do any outlining for catches. Instead, pass the handler
732 // basic block addr to llvm.eh.actions and list the block as a return
734 if (isAsynchronousEHPersonality(Personality)) {
735 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
736 processSEHCatchHandler(CatchAction, StartBB);
741 outlineHandler(Action, &F, LPad, StartBB, FrameVarInfo);
744 // Split the block after the landingpad instruction so that it is just a
745 // call to llvm.eh.actions followed by indirectbr.
746 assert(!isa<PHINode>(LPadBB->begin()) && "lpad phi not removed");
747 SplitBlock(LPadBB, LPad->getNextNode(), DT);
748 // Erase the branch inserted by the split so we can insert indirectbr.
749 LPadBB->getTerminator()->eraseFromParent();
751 // Replace all extracted values with undef and ultimately replace the
752 // landingpad with undef.
753 SmallVector<Instruction *, 4> SEHCodeUses;
754 SmallVector<Instruction *, 4> EHUndefs;
755 for (User *U : LPad->users()) {
756 auto *E = dyn_cast<ExtractValueInst>(U);
759 assert(E->getNumIndices() == 1 &&
760 "Unexpected operation: extracting both landing pad values");
761 unsigned Idx = *E->idx_begin();
762 assert((Idx == 0 || Idx == 1) && "unexpected index");
763 if (Idx == 0 && isAsynchronousEHPersonality(Personality))
764 SEHCodeUses.push_back(E);
766 EHUndefs.push_back(E);
768 for (Instruction *E : EHUndefs) {
769 E->replaceAllUsesWith(UndefValue::get(E->getType()));
770 E->eraseFromParent();
772 LPad->replaceAllUsesWith(UndefValue::get(LPad->getType()));
774 // Rewrite uses of the exception pointer to loads of an alloca.
775 for (Instruction *E : SEHCodeUses) {
776 SmallVector<Use *, 4> Uses;
777 for (Use &U : E->uses())
779 for (Use *U : Uses) {
780 auto *I = cast<Instruction>(U->getUser());
781 if (isa<ResumeInst>(I))
784 if (auto *Phi = dyn_cast<PHINode>(I))
785 LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false,
786 Phi->getIncomingBlock(*U));
788 LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false, I);
791 E->replaceAllUsesWith(UndefValue::get(E->getType()));
792 E->eraseFromParent();
795 // Add a call to describe the actions for this landing pad.
796 std::vector<Value *> ActionArgs;
797 for (ActionHandler *Action : Actions) {
798 // Action codes from docs are: 0 cleanup, 1 catch.
799 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
800 ActionArgs.push_back(ConstantInt::get(Int32Type, 1));
801 ActionArgs.push_back(CatchAction->getSelector());
802 // Find the frame escape index of the exception object alloca in the
804 int FrameEscapeIdx = -1;
805 Value *EHObj = const_cast<Value *>(CatchAction->getExceptionVar());
806 if (EHObj && !isa<ConstantPointerNull>(EHObj)) {
807 auto I = FrameVarInfo.find(EHObj);
808 assert(I != FrameVarInfo.end() &&
809 "failed to map llvm.eh.begincatch var");
810 FrameEscapeIdx = std::distance(FrameVarInfo.begin(), I);
812 ActionArgs.push_back(ConstantInt::get(Int32Type, FrameEscapeIdx));
814 ActionArgs.push_back(ConstantInt::get(Int32Type, 0));
816 ActionArgs.push_back(Action->getHandlerBlockOrFunc());
819 CallInst::Create(ActionIntrin, ActionArgs, "recover", LPadBB);
821 // Add an indirect branch listing possible successors of the catch handlers.
822 SetVector<BasicBlock *> ReturnTargets;
823 for (ActionHandler *Action : Actions) {
824 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
825 const auto &CatchTargets = CatchAction->getReturnTargets();
826 ReturnTargets.insert(CatchTargets.begin(), CatchTargets.end());
829 IndirectBrInst *Branch =
830 IndirectBrInst::Create(Recover, ReturnTargets.size(), LPadBB);
831 for (BasicBlock *Target : ReturnTargets)
832 Branch->addDestination(Target);
833 } // End for each landingpad
835 // If nothing got outlined, there is no more processing to be done.
836 if (!HandlersOutlined)
839 // Replace any nested landing pad stubs with the correct action handler.
840 // This must be done before we remove unreachable blocks because it
841 // cleans up references to outlined blocks that will be deleted.
842 for (auto &LPadPair : NestedLPtoOriginalLP)
843 completeNestedLandingPad(&F, LPadPair.first, LPadPair.second, FrameVarInfo);
844 NestedLPtoOriginalLP.clear();
846 F.addFnAttr("wineh-parent", F.getName());
848 // Delete any blocks that were only used by handlers that were outlined above.
849 removeUnreachableBlocks(F);
851 BasicBlock *Entry = &F.getEntryBlock();
852 IRBuilder<> Builder(F.getParent()->getContext());
853 Builder.SetInsertPoint(Entry->getFirstInsertionPt());
855 Function *FrameEscapeFn =
856 Intrinsic::getDeclaration(M, Intrinsic::frameescape);
857 Function *RecoverFrameFn =
858 Intrinsic::getDeclaration(M, Intrinsic::framerecover);
859 SmallVector<Value *, 8> AllocasToEscape;
861 // Scan the entry block for an existing call to llvm.frameescape. We need to
862 // keep escaping those objects.
863 for (Instruction &I : F.front()) {
864 auto *II = dyn_cast<IntrinsicInst>(&I);
865 if (II && II->getIntrinsicID() == Intrinsic::frameescape) {
866 auto Args = II->arg_operands();
867 AllocasToEscape.append(Args.begin(), Args.end());
868 II->eraseFromParent();
873 // Finally, replace all of the temporary allocas for frame variables used in
874 // the outlined handlers with calls to llvm.framerecover.
875 for (auto &VarInfoEntry : FrameVarInfo) {
876 Value *ParentVal = VarInfoEntry.first;
877 TinyPtrVector<AllocaInst *> &Allocas = VarInfoEntry.second;
878 AllocaInst *ParentAlloca = cast<AllocaInst>(ParentVal);
880 // FIXME: We should try to sink unescaped allocas from the parent frame into
881 // the child frame. If the alloca is escaped, we have to use the lifetime
882 // markers to ensure that the alloca is only live within the child frame.
884 // Add this alloca to the list of things to escape.
885 AllocasToEscape.push_back(ParentAlloca);
887 // Next replace all outlined allocas that are mapped to it.
888 for (AllocaInst *TempAlloca : Allocas) {
889 if (TempAlloca == getCatchObjectSentinel())
890 continue; // Skip catch parameter sentinels.
891 Function *HandlerFn = TempAlloca->getParent()->getParent();
892 llvm::Value *FP = HandlerToParentFP[HandlerFn];
895 // FIXME: Sink this framerecover into the blocks where it is used.
896 Builder.SetInsertPoint(TempAlloca);
897 Builder.SetCurrentDebugLocation(TempAlloca->getDebugLoc());
898 Value *RecoverArgs[] = {
899 Builder.CreateBitCast(&F, Int8PtrType, ""), FP,
900 llvm::ConstantInt::get(Int32Type, AllocasToEscape.size() - 1)};
901 Instruction *RecoveredAlloca =
902 Builder.CreateCall(RecoverFrameFn, RecoverArgs);
904 // Add a pointer bitcast if the alloca wasn't an i8.
905 if (RecoveredAlloca->getType() != TempAlloca->getType()) {
906 RecoveredAlloca->setName(Twine(TempAlloca->getName()) + ".i8");
907 RecoveredAlloca = cast<Instruction>(
908 Builder.CreateBitCast(RecoveredAlloca, TempAlloca->getType()));
910 TempAlloca->replaceAllUsesWith(RecoveredAlloca);
911 TempAlloca->removeFromParent();
912 RecoveredAlloca->takeName(TempAlloca);
915 } // End for each FrameVarInfo entry.
917 // Insert 'call void (...)* @llvm.frameescape(...)' at the end of the entry
919 Builder.SetInsertPoint(&F.getEntryBlock().back());
920 Builder.CreateCall(FrameEscapeFn, AllocasToEscape);
922 if (SEHExceptionCodeSlot) {
923 if (SEHExceptionCodeSlot->hasNUses(0))
924 SEHExceptionCodeSlot->eraseFromParent();
926 PromoteMemToReg(SEHExceptionCodeSlot, *DT);
929 // Clean up the handler action maps we created for this function
930 DeleteContainerSeconds(CatchHandlerMap);
931 CatchHandlerMap.clear();
932 DeleteContainerSeconds(CleanupHandlerMap);
933 CleanupHandlerMap.clear();
934 HandlerToParentFP.clear();
937 return HandlersOutlined;
940 void WinEHPrepare::promoteLandingPadValues(LandingPadInst *LPad) {
941 // If the return values of the landing pad instruction are extracted and
942 // stored to memory, we want to promote the store locations to reg values.
943 SmallVector<AllocaInst *, 2> EHAllocas;
945 // The landingpad instruction returns an aggregate value. Typically, its
946 // value will be passed to a pair of extract value instructions and the
947 // results of those extracts are often passed to store instructions.
948 // In unoptimized code the stored value will often be loaded and then stored
950 for (auto *U : LPad->users()) {
951 ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
955 for (auto *EU : Extract->users()) {
956 if (auto *Store = dyn_cast<StoreInst>(EU)) {
957 auto *AV = cast<AllocaInst>(Store->getPointerOperand());
958 EHAllocas.push_back(AV);
963 // We can't do this without a dominator tree.
966 if (!EHAllocas.empty()) {
967 PromoteMemToReg(EHAllocas, *DT);
971 // After promotion, some extracts may be trivially dead. Remove them.
972 SmallVector<Value *, 4> Users(LPad->user_begin(), LPad->user_end());
973 for (auto *U : Users)
974 RecursivelyDeleteTriviallyDeadInstructions(U);
977 void WinEHPrepare::completeNestedLandingPad(Function *ParentFn,
978 LandingPadInst *OutlinedLPad,
979 const LandingPadInst *OriginalLPad,
980 FrameVarInfoMap &FrameVarInfo) {
981 // Get the nested block and erase the unreachable instruction that was
982 // temporarily inserted as its terminator.
983 LLVMContext &Context = ParentFn->getContext();
984 BasicBlock *OutlinedBB = OutlinedLPad->getParent();
985 assert(isa<UnreachableInst>(OutlinedBB->getTerminator()));
986 OutlinedBB->getTerminator()->eraseFromParent();
987 // That should leave OutlinedLPad as the last instruction in its block.
988 assert(&OutlinedBB->back() == OutlinedLPad);
990 // The original landing pad will have already had its action intrinsic
991 // built by the outlining loop. We need to clone that into the outlined
992 // location. It may also be necessary to add references to the exception
993 // variables to the outlined handler in which this landing pad is nested
994 // and remap return instructions in the nested handlers that should return
995 // to an address in the outlined handler.
996 Function *OutlinedHandlerFn = OutlinedBB->getParent();
997 BasicBlock::const_iterator II = OriginalLPad;
999 // The instruction after the landing pad should now be a call to eh.actions.
1000 const Instruction *Recover = II;
1001 assert(match(Recover, m_Intrinsic<Intrinsic::eh_actions>()));
1002 IntrinsicInst *EHActions = cast<IntrinsicInst>(Recover->clone());
1004 // Remap the exception variables into the outlined function.
1005 SmallVector<BlockAddress *, 4> ActionTargets;
1006 SmallVector<ActionHandler *, 4> ActionList;
1007 parseEHActions(EHActions, ActionList);
1008 for (auto *Action : ActionList) {
1009 auto *Catch = dyn_cast<CatchHandler>(Action);
1012 // The dyn_cast to function here selects C++ catch handlers and skips
1013 // SEH catch handlers.
1014 auto *Handler = dyn_cast<Function>(Catch->getHandlerBlockOrFunc());
1017 // Visit all the return instructions, looking for places that return
1018 // to a location within OutlinedHandlerFn.
1019 for (BasicBlock &NestedHandlerBB : *Handler) {
1020 auto *Ret = dyn_cast<ReturnInst>(NestedHandlerBB.getTerminator());
1024 // Handler functions must always return a block address.
1025 BlockAddress *BA = cast<BlockAddress>(Ret->getReturnValue());
1026 // The original target will have been in the main parent function,
1027 // but if it is the address of a block that has been outlined, it
1028 // should be a block that was outlined into OutlinedHandlerFn.
1029 assert(BA->getFunction() == ParentFn);
1031 // Ignore targets that aren't part of OutlinedHandlerFn.
1032 if (!LPadTargetBlocks.count(BA->getBasicBlock()))
1035 // If the return value is the address ofF a block that we
1036 // previously outlined into the parent handler function, replace
1037 // the return instruction and add the mapped target to the list
1038 // of possible return addresses.
1039 BasicBlock *MappedBB = LPadTargetBlocks[BA->getBasicBlock()];
1040 assert(MappedBB->getParent() == OutlinedHandlerFn);
1041 BlockAddress *NewBA = BlockAddress::get(OutlinedHandlerFn, MappedBB);
1042 Ret->eraseFromParent();
1043 ReturnInst::Create(Context, NewBA, &NestedHandlerBB);
1044 ActionTargets.push_back(NewBA);
1047 DeleteContainerPointers(ActionList);
1049 OutlinedBB->getInstList().push_back(EHActions);
1051 // Insert an indirect branch into the outlined landing pad BB.
1052 IndirectBrInst *IBr = IndirectBrInst::Create(EHActions, 0, OutlinedBB);
1053 // Add the previously collected action targets.
1054 for (auto *Target : ActionTargets)
1055 IBr->addDestination(Target->getBasicBlock());
1058 // This function examines a block to determine whether the block ends with a
1059 // conditional branch to a catch handler based on a selector comparison.
1060 // This function is used both by the WinEHPrepare::findSelectorComparison() and
1061 // WinEHCleanupDirector::handleTypeIdFor().
1062 static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler,
1063 Constant *&Selector, BasicBlock *&NextBB) {
1064 ICmpInst::Predicate Pred;
1065 BasicBlock *TBB, *FBB;
1068 if (!match(BB->getTerminator(),
1069 m_Br(m_ICmp(Pred, m_Value(LHS), m_Value(RHS)), TBB, FBB)))
1073 m_Intrinsic<Intrinsic::eh_typeid_for>(m_Constant(Selector))) &&
1074 !match(RHS, m_Intrinsic<Intrinsic::eh_typeid_for>(m_Constant(Selector))))
1077 if (Pred == CmpInst::ICMP_EQ) {
1083 if (Pred == CmpInst::ICMP_NE) {
1092 static bool isCatchBlock(BasicBlock *BB) {
1093 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
1095 if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_begincatch>()))
1101 static BasicBlock *createStubLandingPad(Function *Handler,
1102 Value *PersonalityFn) {
1103 // FIXME: Finish this!
1104 LLVMContext &Context = Handler->getContext();
1105 BasicBlock *StubBB = BasicBlock::Create(Context, "stub");
1106 Handler->getBasicBlockList().push_back(StubBB);
1107 IRBuilder<> Builder(StubBB);
1108 LandingPadInst *LPad = Builder.CreateLandingPad(
1109 llvm::StructType::get(Type::getInt8PtrTy(Context),
1110 Type::getInt32Ty(Context), nullptr),
1112 // Insert a call to llvm.eh.actions so that we don't try to outline this lpad.
1113 Function *ActionIntrin =
1114 Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::eh_actions);
1115 Builder.CreateCall(ActionIntrin, "recover");
1116 LPad->setCleanup(true);
1117 Builder.CreateUnreachable();
1121 // Cycles through the blocks in an outlined handler function looking for an
1122 // invoke instruction and inserts an invoke of llvm.donothing with an empty
1123 // landing pad if none is found. The code that generates the .xdata tables for
1124 // the handler needs at least one landing pad to identify the parent function's
1126 void WinEHPrepare::addStubInvokeToHandlerIfNeeded(Function *Handler,
1127 Value *PersonalityFn) {
1128 ReturnInst *Ret = nullptr;
1129 UnreachableInst *Unreached = nullptr;
1130 for (BasicBlock &BB : *Handler) {
1131 TerminatorInst *Terminator = BB.getTerminator();
1132 // If we find an invoke, there is nothing to be done.
1133 auto *II = dyn_cast<InvokeInst>(Terminator);
1136 // If we've already recorded a return instruction, keep looking for invokes.
1138 Ret = dyn_cast<ReturnInst>(Terminator);
1139 // If we haven't recorded an unreachable instruction, try this terminator.
1141 Unreached = dyn_cast<UnreachableInst>(Terminator);
1144 // If we got this far, the handler contains no invokes. We should have seen
1145 // at least one return or unreachable instruction. We'll insert an invoke of
1146 // llvm.donothing ahead of that instruction.
1147 assert(Ret || Unreached);
1148 TerminatorInst *Term;
1153 BasicBlock *OldRetBB = Term->getParent();
1154 BasicBlock *NewRetBB = SplitBlock(OldRetBB, Term, DT);
1155 // SplitBlock adds an unconditional branch instruction at the end of the
1156 // parent block. We want to replace that with an invoke call, so we can
1158 OldRetBB->getTerminator()->eraseFromParent();
1159 BasicBlock *StubLandingPad = createStubLandingPad(Handler, PersonalityFn);
1161 Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::donothing);
1162 InvokeInst::Create(F, NewRetBB, StubLandingPad, None, "", OldRetBB);
1165 // FIXME: Consider sinking this into lib/Target/X86 somehow. TargetLowering
1166 // usually doesn't build LLVM IR, so that's probably the wrong place.
1167 Function *WinEHPrepare::createHandlerFunc(Type *RetTy, const Twine &Name,
1168 Module *M, Value *&ParentFP) {
1169 // x64 uses a two-argument prototype where the parent FP is the second
1170 // argument. x86 uses no arguments, just the incoming EBP value.
1171 LLVMContext &Context = M->getContext();
1172 FunctionType *FnType;
1173 if (TheTriple.getArch() == Triple::x86_64) {
1174 Type *Int8PtrType = Type::getInt8PtrTy(Context);
1175 Type *ArgTys[2] = {Int8PtrType, Int8PtrType};
1176 FnType = FunctionType::get(RetTy, ArgTys, false);
1178 FnType = FunctionType::get(RetTy, None, false);
1182 Function::Create(FnType, GlobalVariable::InternalLinkage, Name, M);
1183 BasicBlock *Entry = BasicBlock::Create(Context, "entry");
1184 Handler->getBasicBlockList().push_front(Entry);
1185 if (TheTriple.getArch() == Triple::x86_64) {
1186 ParentFP = &(Handler->getArgumentList().back());
1189 Function *FrameAddressFn =
1190 Intrinsic::getDeclaration(M, Intrinsic::frameaddress);
1191 Value *Args[1] = {ConstantInt::get(Type::getInt32Ty(Context), 1)};
1192 ParentFP = CallInst::Create(FrameAddressFn, Args, "parent_fp",
1193 &Handler->getEntryBlock());
1198 bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn,
1199 LandingPadInst *LPad, BasicBlock *StartBB,
1200 FrameVarInfoMap &VarInfo) {
1201 Module *M = SrcFn->getParent();
1202 LLVMContext &Context = M->getContext();
1203 Type *Int8PtrType = Type::getInt8PtrTy(Context);
1205 // Create a new function to receive the handler contents.
1208 if (Action->getType() == Catch) {
1209 Handler = createHandlerFunc(Int8PtrType, SrcFn->getName() + ".catch", M,
1212 Handler = createHandlerFunc(Type::getVoidTy(Context),
1213 SrcFn->getName() + ".cleanup", M, ParentFP);
1215 HandlerToParentFP[Handler] = ParentFP;
1216 Handler->addFnAttr("wineh-parent", SrcFn->getName());
1217 BasicBlock *Entry = &Handler->getEntryBlock();
1219 // Generate a standard prolog to setup the frame recovery structure.
1220 IRBuilder<> Builder(Context);
1221 Builder.SetInsertPoint(Entry);
1222 Builder.SetCurrentDebugLocation(LPad->getDebugLoc());
1224 std::unique_ptr<WinEHCloningDirectorBase> Director;
1226 ValueToValueMapTy VMap;
1228 LandingPadMap &LPadMap = LPadMaps[LPad];
1229 if (!LPadMap.isInitialized())
1230 LPadMap.mapLandingPad(LPad);
1231 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
1232 Constant *Sel = CatchAction->getSelector();
1233 Director.reset(new WinEHCatchDirector(Handler, ParentFP, Sel,
1235 NestedLPtoOriginalLP));
1236 LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
1237 ConstantInt::get(Type::getInt32Ty(Context), 1));
1240 new WinEHCleanupDirector(Handler, ParentFP, VarInfo, LPadMap));
1241 LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
1242 UndefValue::get(Type::getInt32Ty(Context)));
1245 SmallVector<ReturnInst *, 8> Returns;
1246 ClonedCodeInfo OutlinedFunctionInfo;
1248 // If the start block contains PHI nodes, we need to map them.
1249 BasicBlock::iterator II = StartBB->begin();
1250 while (auto *PN = dyn_cast<PHINode>(II)) {
1251 bool Mapped = false;
1252 // Look for PHI values that we have already mapped (such as the selector).
1253 for (Value *Val : PN->incoming_values()) {
1254 if (VMap.count(Val)) {
1255 VMap[PN] = VMap[Val];
1259 // If we didn't find a match for this value, map it as an undef.
1261 VMap[PN] = UndefValue::get(PN->getType());
1266 // The landing pad value may be used by PHI nodes. It will ultimately be
1267 // eliminated, but we need it in the map for intermediate handling.
1268 VMap[LPad] = UndefValue::get(LPad->getType());
1270 // Skip over PHIs and, if applicable, landingpad instructions.
1271 II = StartBB->getFirstInsertionPt();
1273 CloneAndPruneIntoFromInst(Handler, SrcFn, II, VMap,
1274 /*ModuleLevelChanges=*/false, Returns, "",
1275 &OutlinedFunctionInfo, Director.get());
1277 // Move all the instructions in the cloned "entry" block into our entry block.
1278 // Depending on how the parent function was laid out, the block that will
1279 // correspond to the outlined entry block may not be the first block in the
1280 // list. We can recognize it, however, as the cloned block which has no
1281 // predecessors. Any other block wouldn't have been cloned if it didn't
1282 // have a predecessor which was also cloned.
1283 Function::iterator ClonedIt = std::next(Function::iterator(Entry));
1284 while (!pred_empty(ClonedIt))
1286 BasicBlock *ClonedEntryBB = ClonedIt;
1287 assert(ClonedEntryBB);
1288 Entry->getInstList().splice(Entry->end(), ClonedEntryBB->getInstList());
1289 ClonedEntryBB->eraseFromParent();
1291 // Make sure we can identify the handler's personality later.
1292 addStubInvokeToHandlerIfNeeded(Handler, LPad->getPersonalityFn());
1294 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
1295 WinEHCatchDirector *CatchDirector =
1296 reinterpret_cast<WinEHCatchDirector *>(Director.get());
1297 CatchAction->setExceptionVar(CatchDirector->getExceptionVar());
1298 CatchAction->setReturnTargets(CatchDirector->getReturnTargets());
1300 // Look for blocks that are not part of the landing pad that we just
1301 // outlined but terminate with a call to llvm.eh.endcatch and a
1302 // branch to a block that is in the handler we just outlined.
1303 // These blocks will be part of a nested landing pad that intends to
1304 // return to an address in this handler. This case is best handled
1305 // after both landing pads have been outlined, so for now we'll just
1306 // save the association of the blocks in LPadTargetBlocks. The
1307 // return instructions which are created from these branches will be
1308 // replaced after all landing pads have been outlined.
1309 for (const auto MapEntry : VMap) {
1310 // VMap maps all values and blocks that were just cloned, but dead
1311 // blocks which were pruned will map to nullptr.
1312 if (!isa<BasicBlock>(MapEntry.first) || MapEntry.second == nullptr)
1314 const BasicBlock *MappedBB = cast<BasicBlock>(MapEntry.first);
1315 for (auto *Pred : predecessors(const_cast<BasicBlock *>(MappedBB))) {
1316 auto *Branch = dyn_cast<BranchInst>(Pred->getTerminator());
1317 if (!Branch || !Branch->isUnconditional() || Pred->size() <= 1)
1319 BasicBlock::iterator II = const_cast<BranchInst *>(Branch);
1321 if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_endcatch>())) {
1322 // This would indicate that a nested landing pad wants to return
1323 // to a block that is outlined into two different handlers.
1324 assert(!LPadTargetBlocks.count(MappedBB));
1325 LPadTargetBlocks[MappedBB] = cast<BasicBlock>(MapEntry.second);
1329 } // End if (CatchAction)
1331 Action->setHandlerBlockOrFunc(Handler);
1336 /// This BB must end in a selector dispatch. All we need to do is pass the
1337 /// handler block to llvm.eh.actions and list it as a possible indirectbr
1339 void WinEHPrepare::processSEHCatchHandler(CatchHandler *CatchAction,
1340 BasicBlock *StartBB) {
1341 BasicBlock *HandlerBB;
1344 bool Res = isSelectorDispatch(StartBB, HandlerBB, Selector, NextBB);
1346 // If this was EH dispatch, this must be a conditional branch to the handler
1348 // FIXME: Handle instructions in the dispatch block. Currently we drop them,
1349 // leading to crashes if some optimization hoists stuff here.
1350 assert(CatchAction->getSelector() && HandlerBB &&
1351 "expected catch EH dispatch");
1353 // This must be a catch-all. Split the block after the landingpad.
1354 assert(CatchAction->getSelector()->isNullValue() && "expected catch-all");
1355 HandlerBB = SplitBlock(StartBB, StartBB->getFirstInsertionPt(), DT);
1357 IRBuilder<> Builder(HandlerBB->getFirstInsertionPt());
1358 Function *EHCodeFn = Intrinsic::getDeclaration(
1359 StartBB->getParent()->getParent(), Intrinsic::eh_exceptioncode);
1360 Value *Code = Builder.CreateCall(EHCodeFn, "sehcode");
1361 Code = Builder.CreateIntToPtr(Code, SEHExceptionCodeSlot->getAllocatedType());
1362 Builder.CreateStore(Code, SEHExceptionCodeSlot);
1363 CatchAction->setHandlerBlockOrFunc(BlockAddress::get(HandlerBB));
1364 TinyPtrVector<BasicBlock *> Targets(HandlerBB);
1365 CatchAction->setReturnTargets(Targets);
1368 void LandingPadMap::mapLandingPad(const LandingPadInst *LPad) {
1369 // Each instance of this class should only ever be used to map a single
1371 assert(OriginLPad == nullptr || OriginLPad == LPad);
1373 // If the landing pad has already been mapped, there's nothing more to do.
1374 if (OriginLPad == LPad)
1379 // The landingpad instruction returns an aggregate value. Typically, its
1380 // value will be passed to a pair of extract value instructions and the
1381 // results of those extracts will have been promoted to reg values before
1382 // this routine is called.
1383 for (auto *U : LPad->users()) {
1384 const ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
1387 assert(Extract->getNumIndices() == 1 &&
1388 "Unexpected operation: extracting both landing pad values");
1389 unsigned int Idx = *(Extract->idx_begin());
1390 assert((Idx == 0 || Idx == 1) &&
1391 "Unexpected operation: extracting an unknown landing pad element");
1393 ExtractedEHPtrs.push_back(Extract);
1394 } else if (Idx == 1) {
1395 ExtractedSelectors.push_back(Extract);
1400 bool LandingPadMap::isOriginLandingPadBlock(const BasicBlock *BB) const {
1401 return BB->getLandingPadInst() == OriginLPad;
1404 bool LandingPadMap::isLandingPadSpecificInst(const Instruction *Inst) const {
1405 if (Inst == OriginLPad)
1407 for (auto *Extract : ExtractedEHPtrs) {
1408 if (Inst == Extract)
1411 for (auto *Extract : ExtractedSelectors) {
1412 if (Inst == Extract)
1418 void LandingPadMap::remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
1419 Value *SelectorValue) const {
1420 // Remap all landing pad extract instructions to the specified values.
1421 for (auto *Extract : ExtractedEHPtrs)
1422 VMap[Extract] = EHPtrValue;
1423 for (auto *Extract : ExtractedSelectors)
1424 VMap[Extract] = SelectorValue;
1427 static bool isFrameAddressCall(const Value *V) {
1428 return match(const_cast<Value *>(V),
1429 m_Intrinsic<Intrinsic::frameaddress>(m_SpecificInt(0)));
1432 CloningDirector::CloningAction WinEHCloningDirectorBase::handleInstruction(
1433 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1434 // If this is one of the boilerplate landing pad instructions, skip it.
1435 // The instruction will have already been remapped in VMap.
1436 if (LPadMap.isLandingPadSpecificInst(Inst))
1437 return CloningDirector::SkipInstruction;
1439 // Nested landing pads will be cloned as stubs, with just the
1440 // landingpad instruction and an unreachable instruction. When
1441 // all landingpads have been outlined, we'll replace this with the
1442 // llvm.eh.actions call and indirect branch created when the
1443 // landing pad was outlined.
1444 if (auto *LPad = dyn_cast<LandingPadInst>(Inst)) {
1445 return handleLandingPad(VMap, LPad, NewBB);
1448 if (auto *Invoke = dyn_cast<InvokeInst>(Inst))
1449 return handleInvoke(VMap, Invoke, NewBB);
1451 if (auto *Resume = dyn_cast<ResumeInst>(Inst))
1452 return handleResume(VMap, Resume, NewBB);
1454 if (auto *Cmp = dyn_cast<CmpInst>(Inst))
1455 return handleCompare(VMap, Cmp, NewBB);
1457 if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>()))
1458 return handleBeginCatch(VMap, Inst, NewBB);
1459 if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
1460 return handleEndCatch(VMap, Inst, NewBB);
1461 if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
1462 return handleTypeIdFor(VMap, Inst, NewBB);
1464 // When outlining llvm.frameaddress(i32 0), remap that to the second argument,
1465 // which is the FP of the parent.
1466 if (isFrameAddressCall(Inst)) {
1467 VMap[Inst] = ParentFP;
1468 return CloningDirector::SkipInstruction;
1471 // Continue with the default cloning behavior.
1472 return CloningDirector::CloneInstruction;
1475 CloningDirector::CloningAction WinEHCatchDirector::handleLandingPad(
1476 ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
1477 Instruction *NewInst = LPad->clone();
1478 if (LPad->hasName())
1479 NewInst->setName(LPad->getName());
1480 // Save this correlation for later processing.
1481 NestedLPtoOriginalLP[cast<LandingPadInst>(NewInst)] = LPad;
1482 VMap[LPad] = NewInst;
1483 BasicBlock::InstListType &InstList = NewBB->getInstList();
1484 InstList.push_back(NewInst);
1485 InstList.push_back(new UnreachableInst(NewBB->getContext()));
1486 return CloningDirector::StopCloningBB;
1489 CloningDirector::CloningAction WinEHCatchDirector::handleBeginCatch(
1490 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1491 // The argument to the call is some form of the first element of the
1492 // landingpad aggregate value, but that doesn't matter. It isn't used
1494 // The second argument is an outparameter where the exception object will be
1495 // stored. Typically the exception object is a scalar, but it can be an
1496 // aggregate when catching by value.
1497 // FIXME: Leave something behind to indicate where the exception object lives
1498 // for this handler. Should it be part of llvm.eh.actions?
1499 assert(ExceptionObjectVar == nullptr && "Multiple calls to "
1500 "llvm.eh.begincatch found while "
1501 "outlining catch handler.");
1502 ExceptionObjectVar = Inst->getOperand(1)->stripPointerCasts();
1503 if (isa<ConstantPointerNull>(ExceptionObjectVar))
1504 return CloningDirector::SkipInstruction;
1505 assert(cast<AllocaInst>(ExceptionObjectVar)->isStaticAlloca() &&
1506 "catch parameter is not static alloca");
1507 Materializer.escapeCatchObject(ExceptionObjectVar);
1508 return CloningDirector::SkipInstruction;
1511 CloningDirector::CloningAction
1512 WinEHCatchDirector::handleEndCatch(ValueToValueMapTy &VMap,
1513 const Instruction *Inst, BasicBlock *NewBB) {
1514 auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst);
1515 // It might be interesting to track whether or not we are inside a catch
1516 // function, but that might make the algorithm more brittle than it needs
1519 // The end catch call can occur in one of two places: either in a
1520 // landingpad block that is part of the catch handlers exception mechanism,
1521 // or at the end of the catch block. However, a catch-all handler may call
1522 // end catch from the original landing pad. If the call occurs in a nested
1523 // landing pad block, we must skip it and continue so that the landing pad
1525 auto *ParentBB = IntrinCall->getParent();
1526 if (ParentBB->isLandingPad() && !LPadMap.isOriginLandingPadBlock(ParentBB))
1527 return CloningDirector::SkipInstruction;
1529 // If an end catch occurs anywhere else we want to terminate the handler
1530 // with a return to the code that follows the endcatch call. If the
1531 // next instruction is not an unconditional branch, we need to split the
1532 // block to provide a clear target for the return instruction.
1533 BasicBlock *ContinueBB;
1534 auto Next = std::next(BasicBlock::const_iterator(IntrinCall));
1535 const BranchInst *Branch = dyn_cast<BranchInst>(Next);
1536 if (!Branch || !Branch->isUnconditional()) {
1537 // We're interrupting the cloning process at this location, so the
1538 // const_cast we're doing here will not cause a problem.
1539 ContinueBB = SplitBlock(const_cast<BasicBlock *>(ParentBB),
1540 const_cast<Instruction *>(cast<Instruction>(Next)));
1542 ContinueBB = Branch->getSuccessor(0);
1545 ReturnInst::Create(NewBB->getContext(), BlockAddress::get(ContinueBB), NewBB);
1546 ReturnTargets.push_back(ContinueBB);
1548 // We just added a terminator to the cloned block.
1549 // Tell the caller to stop processing the current basic block so that
1550 // the branch instruction will be skipped.
1551 return CloningDirector::StopCloningBB;
1554 CloningDirector::CloningAction WinEHCatchDirector::handleTypeIdFor(
1555 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1556 auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst);
1557 Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts();
1558 // This causes a replacement that will collapse the landing pad CFG based
1559 // on the filter function we intend to match.
1560 if (Selector == CurrentSelector)
1561 VMap[Inst] = ConstantInt::get(SelectorIDType, 1);
1563 VMap[Inst] = ConstantInt::get(SelectorIDType, 0);
1564 // Tell the caller not to clone this instruction.
1565 return CloningDirector::SkipInstruction;
1568 CloningDirector::CloningAction
1569 WinEHCatchDirector::handleInvoke(ValueToValueMapTy &VMap,
1570 const InvokeInst *Invoke, BasicBlock *NewBB) {
1571 return CloningDirector::CloneInstruction;
1574 CloningDirector::CloningAction
1575 WinEHCatchDirector::handleResume(ValueToValueMapTy &VMap,
1576 const ResumeInst *Resume, BasicBlock *NewBB) {
1577 // Resume instructions shouldn't be reachable from catch handlers.
1578 // We still need to handle it, but it will be pruned.
1579 BasicBlock::InstListType &InstList = NewBB->getInstList();
1580 InstList.push_back(new UnreachableInst(NewBB->getContext()));
1581 return CloningDirector::StopCloningBB;
1584 CloningDirector::CloningAction
1585 WinEHCatchDirector::handleCompare(ValueToValueMapTy &VMap,
1586 const CmpInst *Compare, BasicBlock *NewBB) {
1587 const IntrinsicInst *IntrinCall = nullptr;
1588 if (match(Compare->getOperand(0), m_Intrinsic<Intrinsic::eh_typeid_for>())) {
1589 IntrinCall = dyn_cast<IntrinsicInst>(Compare->getOperand(0));
1590 } else if (match(Compare->getOperand(1),
1591 m_Intrinsic<Intrinsic::eh_typeid_for>())) {
1592 IntrinCall = dyn_cast<IntrinsicInst>(Compare->getOperand(1));
1595 Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts();
1596 // This causes a replacement that will collapse the landing pad CFG based
1597 // on the filter function we intend to match.
1598 if (Selector == CurrentSelector->stripPointerCasts()) {
1599 VMap[Compare] = ConstantInt::get(SelectorIDType, 1);
1601 VMap[Compare] = ConstantInt::get(SelectorIDType, 0);
1603 return CloningDirector::SkipInstruction;
1605 return CloningDirector::CloneInstruction;
1608 CloningDirector::CloningAction WinEHCleanupDirector::handleLandingPad(
1609 ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
1610 // The MS runtime will terminate the process if an exception occurs in a
1611 // cleanup handler, so we shouldn't encounter landing pads in the actual
1612 // cleanup code, but they may appear in catch blocks. Depending on where
1613 // we started cloning we may see one, but it will get dropped during dead
1615 Instruction *NewInst = new UnreachableInst(NewBB->getContext());
1616 VMap[LPad] = NewInst;
1617 BasicBlock::InstListType &InstList = NewBB->getInstList();
1618 InstList.push_back(NewInst);
1619 return CloningDirector::StopCloningBB;
1622 CloningDirector::CloningAction WinEHCleanupDirector::handleBeginCatch(
1623 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1624 // Cleanup code may flow into catch blocks or the catch block may be part
1625 // of a branch that will be optimized away. We'll insert a return
1626 // instruction now, but it may be pruned before the cloning process is
1628 ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
1629 return CloningDirector::StopCloningBB;
1632 CloningDirector::CloningAction WinEHCleanupDirector::handleEndCatch(
1633 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1634 // Cleanup handlers nested within catch handlers may begin with a call to
1635 // eh.endcatch. We can just ignore that instruction.
1636 return CloningDirector::SkipInstruction;
1639 CloningDirector::CloningAction WinEHCleanupDirector::handleTypeIdFor(
1640 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1641 // If we encounter a selector comparison while cloning a cleanup handler,
1642 // we want to stop cloning immediately. Anything after the dispatch
1643 // will be outlined into a different handler.
1644 BasicBlock *CatchHandler;
1647 if (isSelectorDispatch(const_cast<BasicBlock *>(Inst->getParent()),
1648 CatchHandler, Selector, NextBB)) {
1649 ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
1650 return CloningDirector::StopCloningBB;
1652 // If eg.typeid.for is called for any other reason, it can be ignored.
1653 VMap[Inst] = ConstantInt::get(SelectorIDType, 0);
1654 return CloningDirector::SkipInstruction;
1657 CloningDirector::CloningAction WinEHCleanupDirector::handleInvoke(
1658 ValueToValueMapTy &VMap, const InvokeInst *Invoke, BasicBlock *NewBB) {
1659 // All invokes in cleanup handlers can be replaced with calls.
1660 SmallVector<Value *, 16> CallArgs(Invoke->op_begin(), Invoke->op_end() - 3);
1661 // Insert a normal call instruction...
1663 CallInst::Create(const_cast<Value *>(Invoke->getCalledValue()), CallArgs,
1664 Invoke->getName(), NewBB);
1665 NewCall->setCallingConv(Invoke->getCallingConv());
1666 NewCall->setAttributes(Invoke->getAttributes());
1667 NewCall->setDebugLoc(Invoke->getDebugLoc());
1668 VMap[Invoke] = NewCall;
1670 // Remap the operands.
1671 llvm::RemapInstruction(NewCall, VMap, RF_None, nullptr, &Materializer);
1673 // Insert an unconditional branch to the normal destination.
1674 BranchInst::Create(Invoke->getNormalDest(), NewBB);
1676 // The unwind destination won't be cloned into the new function, so
1677 // we don't need to clean up its phi nodes.
1679 // We just added a terminator to the cloned block.
1680 // Tell the caller to stop processing the current basic block.
1681 return CloningDirector::CloneSuccessors;
1684 CloningDirector::CloningAction WinEHCleanupDirector::handleResume(
1685 ValueToValueMapTy &VMap, const ResumeInst *Resume, BasicBlock *NewBB) {
1686 ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
1688 // We just added a terminator to the cloned block.
1689 // Tell the caller to stop processing the current basic block so that
1690 // the branch instruction will be skipped.
1691 return CloningDirector::StopCloningBB;
1694 CloningDirector::CloningAction
1695 WinEHCleanupDirector::handleCompare(ValueToValueMapTy &VMap,
1696 const CmpInst *Compare, BasicBlock *NewBB) {
1697 if (match(Compare->getOperand(0), m_Intrinsic<Intrinsic::eh_typeid_for>()) ||
1698 match(Compare->getOperand(1), m_Intrinsic<Intrinsic::eh_typeid_for>())) {
1699 VMap[Compare] = ConstantInt::get(SelectorIDType, 1);
1700 return CloningDirector::SkipInstruction;
1702 return CloningDirector::CloneInstruction;
1705 WinEHFrameVariableMaterializer::WinEHFrameVariableMaterializer(
1706 Function *OutlinedFn, Value *ParentFP, FrameVarInfoMap &FrameVarInfo)
1707 : FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) {
1708 BasicBlock *EntryBB = &OutlinedFn->getEntryBlock();
1710 // New allocas should be inserted in the entry block, but after the parent FP
1711 // is established if it is an instruction.
1712 Instruction *InsertPoint = EntryBB->getFirstInsertionPt();
1713 if (auto *FPInst = dyn_cast<Instruction>(ParentFP))
1714 InsertPoint = FPInst->getNextNode();
1715 Builder.SetInsertPoint(EntryBB, InsertPoint);
1718 Value *WinEHFrameVariableMaterializer::materializeValueFor(Value *V) {
1719 // If we're asked to materialize a static alloca, we temporarily create an
1720 // alloca in the outlined function and add this to the FrameVarInfo map. When
1721 // all the outlining is complete, we'll replace these temporary allocas with
1722 // calls to llvm.framerecover.
1723 if (auto *AV = dyn_cast<AllocaInst>(V)) {
1724 assert(AV->isStaticAlloca() &&
1725 "cannot materialize un-demoted dynamic alloca");
1726 AllocaInst *NewAlloca = dyn_cast<AllocaInst>(AV->clone());
1727 Builder.Insert(NewAlloca, AV->getName());
1728 FrameVarInfo[AV].push_back(NewAlloca);
1732 if (isa<Instruction>(V) || isa<Argument>(V)) {
1733 errs() << "Failed to demote instruction used in exception handler:\n";
1734 errs() << " " << *V << '\n';
1735 report_fatal_error("WinEHPrepare failed to demote instruction");
1738 // Don't materialize other values.
1742 void WinEHFrameVariableMaterializer::escapeCatchObject(Value *V) {
1743 // Catch parameter objects have to live in the parent frame. When we see a use
1744 // of a catch parameter, add a sentinel to the multimap to indicate that it's
1745 // used from another handler. This will prevent us from trying to sink the
1746 // alloca into the handler and ensure that the catch parameter is present in
1747 // the call to llvm.frameescape.
1748 FrameVarInfo[V].push_back(getCatchObjectSentinel());
1751 // This function maps the catch and cleanup handlers that are reachable from the
1752 // specified landing pad. The landing pad sequence will have this basic shape:
1754 // <cleanup handler>
1755 // <selector comparison>
1757 // <cleanup handler>
1758 // <selector comparison>
1760 // <cleanup handler>
1763 // Any of the cleanup slots may be absent. The cleanup slots may be occupied by
1764 // any arbitrary control flow, but all paths through the cleanup code must
1765 // eventually reach the next selector comparison and no path can skip to a
1766 // different selector comparisons, though some paths may terminate abnormally.
1767 // Therefore, we will use a depth first search from the start of any given
1768 // cleanup block and stop searching when we find the next selector comparison.
1770 // If the landingpad instruction does not have a catch clause, we will assume
1771 // that any instructions other than selector comparisons and catch handlers can
1772 // be ignored. In practice, these will only be the boilerplate instructions.
1774 // The catch handlers may also have any control structure, but we are only
1775 // interested in the start of the catch handlers, so we don't need to actually
1776 // follow the flow of the catch handlers. The start of the catch handlers can
1777 // be located from the compare instructions, but they can be skipped in the
1778 // flow by following the contrary branch.
1779 void WinEHPrepare::mapLandingPadBlocks(LandingPadInst *LPad,
1780 LandingPadActions &Actions) {
1781 unsigned int NumClauses = LPad->getNumClauses();
1782 unsigned int HandlersFound = 0;
1783 BasicBlock *BB = LPad->getParent();
1785 DEBUG(dbgs() << "Mapping landing pad: " << BB->getName() << "\n");
1787 if (NumClauses == 0) {
1788 findCleanupHandlers(Actions, BB, nullptr);
1792 VisitedBlockSet VisitedBlocks;
1794 while (HandlersFound != NumClauses) {
1795 BasicBlock *NextBB = nullptr;
1797 // Skip over filter clauses.
1798 if (LPad->isFilter(HandlersFound)) {
1803 // See if the clause we're looking for is a catch-all.
1804 // If so, the catch begins immediately.
1805 Constant *ExpectedSelector =
1806 LPad->getClause(HandlersFound)->stripPointerCasts();
1807 if (isa<ConstantPointerNull>(ExpectedSelector)) {
1808 // The catch all must occur last.
1809 assert(HandlersFound == NumClauses - 1);
1811 // There can be additional selector dispatches in the call chain that we
1813 BasicBlock *CatchBlock = nullptr;
1815 while (BB && isSelectorDispatch(BB, CatchBlock, Selector, NextBB)) {
1816 DEBUG(dbgs() << " Found extra catch dispatch in block "
1817 << CatchBlock->getName() << "\n");
1821 // Add the catch handler to the action list.
1822 CatchHandler *Action = nullptr;
1823 if (CatchHandlerMap.count(BB) && CatchHandlerMap[BB] != nullptr) {
1824 // If the CatchHandlerMap already has an entry for this BB, re-use it.
1825 Action = CatchHandlerMap[BB];
1826 assert(Action->getSelector() == ExpectedSelector);
1828 // We don't expect a selector dispatch, but there may be a call to
1829 // llvm.eh.begincatch, which separates catch handling code from
1830 // cleanup code in the same control flow. This call looks for the
1831 // begincatch intrinsic.
1832 Action = findCatchHandler(BB, NextBB, VisitedBlocks);
1834 // For C++ EH, check if there is any interesting cleanup code before
1835 // we begin the catch. This is important because cleanups cannot
1836 // rethrow exceptions but code called from catches can. For SEH, it
1837 // isn't important if some finally code before a catch-all is executed
1838 // out of line or after recovering from the exception.
1839 if (Personality == EHPersonality::MSVC_CXX)
1840 findCleanupHandlers(Actions, BB, BB);
1842 // If an action was not found, it means that the control flows
1843 // directly into the catch-all handler and there is no cleanup code.
1844 // That's an expected situation and we must create a catch action.
1845 // Since this is a catch-all handler, the selector won't actually
1846 // appear in the code anywhere. ExpectedSelector here is the constant
1847 // null ptr that we got from the landing pad instruction.
1848 Action = new CatchHandler(BB, ExpectedSelector, nullptr);
1849 CatchHandlerMap[BB] = Action;
1852 Actions.insertCatchHandler(Action);
1853 DEBUG(dbgs() << " Catch all handler at block " << BB->getName() << "\n");
1856 // Once we reach a catch-all, don't expect to hit a resume instruction.
1861 CatchHandler *CatchAction = findCatchHandler(BB, NextBB, VisitedBlocks);
1862 assert(CatchAction);
1864 // See if there is any interesting code executed before the dispatch.
1865 findCleanupHandlers(Actions, BB, CatchAction->getStartBlock());
1867 // When the source program contains multiple nested try blocks the catch
1868 // handlers can get strung together in such a way that we can encounter
1869 // a dispatch for a selector that we've already had a handler for.
1870 if (CatchAction->getSelector()->stripPointerCasts() == ExpectedSelector) {
1873 // Add the catch handler to the action list.
1874 DEBUG(dbgs() << " Found catch dispatch in block "
1875 << CatchAction->getStartBlock()->getName() << "\n");
1876 Actions.insertCatchHandler(CatchAction);
1878 // Under some circumstances optimized IR will flow unconditionally into a
1879 // handler block without checking the selector. This can only happen if
1880 // the landing pad has a catch-all handler and the handler for the
1881 // preceeding catch clause is identical to the catch-call handler
1882 // (typically an empty catch). In this case, the handler must be shared
1883 // by all remaining clauses.
1884 if (isa<ConstantPointerNull>(
1885 CatchAction->getSelector()->stripPointerCasts())) {
1886 DEBUG(dbgs() << " Applying early catch-all handler in block "
1887 << CatchAction->getStartBlock()->getName()
1888 << " to all remaining clauses.\n");
1889 Actions.insertCatchHandler(CatchAction);
1893 DEBUG(dbgs() << " Found extra catch dispatch in block "
1894 << CatchAction->getStartBlock()->getName() << "\n");
1897 // Move on to the block after the catch handler.
1901 // If we didn't wind up in a catch-all, see if there is any interesting code
1902 // executed before the resume.
1903 findCleanupHandlers(Actions, BB, BB);
1905 // It's possible that some optimization moved code into a landingpad that
1907 // previously being used for cleanup. If that happens, we need to execute
1909 // extra code from a cleanup handler.
1910 if (Actions.includesCleanup() && !LPad->isCleanup())
1911 LPad->setCleanup(true);
1914 // This function searches starting with the input block for the next
1915 // block that terminates with a branch whose condition is based on a selector
1916 // comparison. This may be the input block. See the mapLandingPadBlocks
1917 // comments for a discussion of control flow assumptions.
1919 CatchHandler *WinEHPrepare::findCatchHandler(BasicBlock *BB,
1920 BasicBlock *&NextBB,
1921 VisitedBlockSet &VisitedBlocks) {
1922 // See if we've already found a catch handler use it.
1923 // Call count() first to avoid creating a null entry for blocks
1924 // we haven't seen before.
1925 if (CatchHandlerMap.count(BB) && CatchHandlerMap[BB] != nullptr) {
1926 CatchHandler *Action = cast<CatchHandler>(CatchHandlerMap[BB]);
1927 NextBB = Action->getNextBB();
1931 // VisitedBlocks applies only to the current search. We still
1932 // need to consider blocks that we've visited while mapping other
1934 VisitedBlocks.insert(BB);
1936 BasicBlock *CatchBlock = nullptr;
1937 Constant *Selector = nullptr;
1939 // If this is the first time we've visited this block from any landing pad
1940 // look to see if it is a selector dispatch block.
1941 if (!CatchHandlerMap.count(BB)) {
1942 if (isSelectorDispatch(BB, CatchBlock, Selector, NextBB)) {
1943 CatchHandler *Action = new CatchHandler(BB, Selector, NextBB);
1944 CatchHandlerMap[BB] = Action;
1947 // If we encounter a block containing an llvm.eh.begincatch before we
1948 // find a selector dispatch block, the handler is assumed to be
1949 // reached unconditionally. This happens for catch-all blocks, but
1950 // it can also happen for other catch handlers that have been combined
1951 // with the catch-all handler during optimization.
1952 if (isCatchBlock(BB)) {
1953 PointerType *Int8PtrTy = Type::getInt8PtrTy(BB->getContext());
1954 Constant *NullSelector = ConstantPointerNull::get(Int8PtrTy);
1955 CatchHandler *Action = new CatchHandler(BB, NullSelector, nullptr);
1956 CatchHandlerMap[BB] = Action;
1961 // Visit each successor, looking for the dispatch.
1962 // FIXME: We expect to find the dispatch quickly, so this will probably
1963 // work better as a breadth first search.
1964 for (BasicBlock *Succ : successors(BB)) {
1965 if (VisitedBlocks.count(Succ))
1968 CatchHandler *Action = findCatchHandler(Succ, NextBB, VisitedBlocks);
1975 // These are helper functions to combine repeated code from findCleanupHandlers.
1976 static void createCleanupHandler(LandingPadActions &Actions,
1977 CleanupHandlerMapTy &CleanupHandlerMap,
1979 CleanupHandler *Action = new CleanupHandler(BB);
1980 CleanupHandlerMap[BB] = Action;
1981 Actions.insertCleanupHandler(Action);
1982 DEBUG(dbgs() << " Found cleanup code in block "
1983 << Action->getStartBlock()->getName() << "\n");
1986 static CallSite matchOutlinedFinallyCall(BasicBlock *BB,
1987 Instruction *MaybeCall) {
1988 // Look for finally blocks that Clang has already outlined for us.
1989 // %fp = call i8* @llvm.frameaddress(i32 0)
1990 // call void @"fin$parent"(iN 1, i8* %fp)
1991 if (isFrameAddressCall(MaybeCall) && MaybeCall != BB->getTerminator())
1992 MaybeCall = MaybeCall->getNextNode();
1993 CallSite FinallyCall(MaybeCall);
1994 if (!FinallyCall || FinallyCall.arg_size() != 2)
1996 if (!match(FinallyCall.getArgument(0), m_SpecificInt(1)))
1998 if (!isFrameAddressCall(FinallyCall.getArgument(1)))
2003 static BasicBlock *followSingleUnconditionalBranches(BasicBlock *BB) {
2004 // Skip single ubr blocks.
2005 while (BB->getFirstNonPHIOrDbg() == BB->getTerminator()) {
2006 auto *Br = dyn_cast<BranchInst>(BB->getTerminator());
2007 if (Br && Br->isUnconditional())
2008 BB = Br->getSuccessor(0);
2015 // This function searches starting with the input block for the next block that
2016 // contains code that is not part of a catch handler and would not be eliminated
2017 // during handler outlining.
2019 void WinEHPrepare::findCleanupHandlers(LandingPadActions &Actions,
2020 BasicBlock *StartBB, BasicBlock *EndBB) {
2021 // Here we will skip over the following:
2023 // landing pad prolog:
2025 // Unconditional branches
2027 // Selector dispatch
2031 // Anything else marks the start of an interesting block
2033 BasicBlock *BB = StartBB;
2034 // Anything other than an unconditional branch will kick us out of this loop
2035 // one way or another.
2037 BB = followSingleUnconditionalBranches(BB);
2038 // If we've already scanned this block, don't scan it again. If it is
2039 // a cleanup block, there will be an action in the CleanupHandlerMap.
2040 // If we've scanned it and it is not a cleanup block, there will be a
2041 // nullptr in the CleanupHandlerMap. If we have not scanned it, there will
2042 // be no entry in the CleanupHandlerMap. We must call count() first to
2043 // avoid creating a null entry for blocks we haven't scanned.
2044 if (CleanupHandlerMap.count(BB)) {
2045 if (auto *Action = CleanupHandlerMap[BB]) {
2046 Actions.insertCleanupHandler(Action);
2047 DEBUG(dbgs() << " Found cleanup code in block "
2048 << Action->getStartBlock()->getName() << "\n");
2049 // FIXME: This cleanup might chain into another, and we need to discover
2053 // Here we handle the case where the cleanup handler map contains a
2054 // value for this block but the value is a nullptr. This means that
2055 // we have previously analyzed the block and determined that it did
2056 // not contain any cleanup code. Based on the earlier analysis, we
2057 // know the the block must end in either an unconditional branch, a
2058 // resume or a conditional branch that is predicated on a comparison
2059 // with a selector. Either the resume or the selector dispatch
2060 // would terminate the search for cleanup code, so the unconditional
2061 // branch is the only case for which we might need to continue
2063 BasicBlock *SuccBB = followSingleUnconditionalBranches(BB);
2064 if (SuccBB == BB || SuccBB == EndBB)
2071 // Create an entry in the cleanup handler map for this block. Initially
2072 // we create an entry that says this isn't a cleanup block. If we find
2073 // cleanup code, the caller will replace this entry.
2074 CleanupHandlerMap[BB] = nullptr;
2076 TerminatorInst *Terminator = BB->getTerminator();
2078 // Landing pad blocks have extra instructions we need to accept.
2079 LandingPadMap *LPadMap = nullptr;
2080 if (BB->isLandingPad()) {
2081 LandingPadInst *LPad = BB->getLandingPadInst();
2082 LPadMap = &LPadMaps[LPad];
2083 if (!LPadMap->isInitialized())
2084 LPadMap->mapLandingPad(LPad);
2087 // Look for the bare resume pattern:
2088 // %lpad.val1 = insertvalue { i8*, i32 } undef, i8* %exn, 0
2089 // %lpad.val2 = insertvalue { i8*, i32 } %lpad.val1, i32 %sel, 1
2090 // resume { i8*, i32 } %lpad.val2
2091 if (auto *Resume = dyn_cast<ResumeInst>(Terminator)) {
2092 InsertValueInst *Insert1 = nullptr;
2093 InsertValueInst *Insert2 = nullptr;
2094 Value *ResumeVal = Resume->getOperand(0);
2095 // If the resume value isn't a phi or landingpad value, it should be a
2096 // series of insertions. Identify them so we can avoid them when scanning
2098 if (!isa<PHINode>(ResumeVal) && !isa<LandingPadInst>(ResumeVal)) {
2099 Insert2 = dyn_cast<InsertValueInst>(ResumeVal);
2101 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2102 Insert1 = dyn_cast<InsertValueInst>(Insert2->getAggregateOperand());
2104 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2106 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
2108 Instruction *Inst = II;
2109 if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
2111 if (Inst == Insert1 || Inst == Insert2 || Inst == Resume)
2113 if (!Inst->hasOneUse() ||
2114 (Inst->user_back() != Insert1 && Inst->user_back() != Insert2)) {
2115 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2121 BranchInst *Branch = dyn_cast<BranchInst>(Terminator);
2122 if (Branch && Branch->isConditional()) {
2123 // Look for the selector dispatch.
2124 // %2 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIf to i8*))
2125 // %matches = icmp eq i32 %sel, %2
2126 // br i1 %matches, label %catch14, label %eh.resume
2127 CmpInst *Compare = dyn_cast<CmpInst>(Branch->getCondition());
2128 if (!Compare || !Compare->isEquality())
2129 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2130 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
2132 Instruction *Inst = II;
2133 if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
2135 if (Inst == Compare || Inst == Branch)
2137 if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
2139 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2141 // The selector dispatch block should always terminate our search.
2142 assert(BB == EndBB);
2146 if (isAsynchronousEHPersonality(Personality)) {
2147 // If this is a landingpad block, split the block at the first non-landing
2149 Instruction *MaybeCall = BB->getFirstNonPHIOrDbg();
2151 while (MaybeCall != BB->getTerminator() &&
2152 LPadMap->isLandingPadSpecificInst(MaybeCall))
2153 MaybeCall = MaybeCall->getNextNode();
2156 // Look for outlined finally calls.
2157 if (CallSite FinallyCall = matchOutlinedFinallyCall(BB, MaybeCall)) {
2158 Function *Fin = FinallyCall.getCalledFunction();
2159 assert(Fin && "outlined finally call should be direct");
2160 auto *Action = new CleanupHandler(BB);
2161 Action->setHandlerBlockOrFunc(Fin);
2162 Actions.insertCleanupHandler(Action);
2163 CleanupHandlerMap[BB] = Action;
2164 DEBUG(dbgs() << " Found frontend-outlined finally call to "
2165 << Fin->getName() << " in block "
2166 << Action->getStartBlock()->getName() << "\n");
2168 // Split the block if there were more interesting instructions and look
2169 // for finally calls in the normal successor block.
2170 BasicBlock *SuccBB = BB;
2171 if (FinallyCall.getInstruction() != BB->getTerminator() &&
2172 FinallyCall.getInstruction()->getNextNode() !=
2173 BB->getTerminator()) {
2175 SplitBlock(BB, FinallyCall.getInstruction()->getNextNode(), DT);
2177 if (FinallyCall.isInvoke()) {
2179 cast<InvokeInst>(FinallyCall.getInstruction())->getNormalDest();
2181 SuccBB = BB->getUniqueSuccessor();
2183 "splitOutlinedFinallyCalls didn't insert a branch");
2193 // Anything else is either a catch block or interesting cleanup code.
2194 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
2196 Instruction *Inst = II;
2197 if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
2199 // Unconditional branches fall through to this loop.
2202 // If this is a catch block, there is no cleanup code to be found.
2203 if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>()))
2205 // If this a nested landing pad, it may contain an endcatch call.
2206 if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
2208 // Anything else makes this interesting cleanup code.
2209 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2212 // Only unconditional branches in empty blocks should get this far.
2213 assert(Branch && Branch->isUnconditional());
2216 BB = Branch->getSuccessor(0);
2220 // This is a public function, declared in WinEHFuncInfo.h and is also
2221 // referenced by WinEHNumbering in FunctionLoweringInfo.cpp.
2222 void llvm::parseEHActions(const IntrinsicInst *II,
2223 SmallVectorImpl<ActionHandler *> &Actions) {
2224 for (unsigned I = 0, E = II->getNumArgOperands(); I != E;) {
2225 uint64_t ActionKind =
2226 cast<ConstantInt>(II->getArgOperand(I))->getZExtValue();
2227 if (ActionKind == /*catch=*/1) {
2228 auto *Selector = cast<Constant>(II->getArgOperand(I + 1));
2229 ConstantInt *EHObjIndex = cast<ConstantInt>(II->getArgOperand(I + 2));
2230 int64_t EHObjIndexVal = EHObjIndex->getSExtValue();
2231 Constant *Handler = cast<Constant>(II->getArgOperand(I + 3));
2233 auto *CH = new CatchHandler(/*BB=*/nullptr, Selector, /*NextBB=*/nullptr);
2234 CH->setHandlerBlockOrFunc(Handler);
2235 CH->setExceptionVarIndex(EHObjIndexVal);
2236 Actions.push_back(CH);
2237 } else if (ActionKind == 0) {
2238 Constant *Handler = cast<Constant>(II->getArgOperand(I + 1));
2240 auto *CH = new CleanupHandler(/*BB=*/nullptr);
2241 CH->setHandlerBlockOrFunc(Handler);
2242 Actions.push_back(CH);
2244 llvm_unreachable("Expected either a catch or cleanup handler!");
2247 std::reverse(Actions.begin(), Actions.end());