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 identifyEHBlocks(Function &F, SmallVectorImpl<LandingPadInst *> &LPads);
95 void promoteLandingPadValues(LandingPadInst *LPad);
96 void demoteValuesLiveAcrossHandlers(Function &F,
97 SmallVectorImpl<LandingPadInst *> &LPads);
98 void findSEHEHReturnPoints(Function &F,
99 SetVector<BasicBlock *> &EHReturnBlocks);
100 void findCXXEHReturnPoints(Function &F,
101 SetVector<BasicBlock *> &EHReturnBlocks);
102 void getPossibleReturnTargets(Function *ParentF, Function *HandlerF,
103 SetVector<BasicBlock*> &Targets);
104 void completeNestedLandingPad(Function *ParentFn,
105 LandingPadInst *OutlinedLPad,
106 const LandingPadInst *OriginalLPad,
107 FrameVarInfoMap &VarInfo);
108 Function *createHandlerFunc(Type *RetTy, const Twine &Name, Module *M,
110 bool outlineHandler(ActionHandler *Action, Function *SrcFn,
111 LandingPadInst *LPad, BasicBlock *StartBB,
112 FrameVarInfoMap &VarInfo);
113 void addStubInvokeToHandlerIfNeeded(Function *Handler, Value *PersonalityFn);
115 void mapLandingPadBlocks(LandingPadInst *LPad, LandingPadActions &Actions);
116 CatchHandler *findCatchHandler(BasicBlock *BB, BasicBlock *&NextBB,
117 VisitedBlockSet &VisitedBlocks);
118 void findCleanupHandlers(LandingPadActions &Actions, BasicBlock *StartBB,
121 void processSEHCatchHandler(CatchHandler *Handler, BasicBlock *StartBB);
125 // All fields are reset by runOnFunction.
126 DominatorTree *DT = nullptr;
127 EHPersonality Personality = EHPersonality::Unknown;
128 CatchHandlerMapTy CatchHandlerMap;
129 CleanupHandlerMapTy CleanupHandlerMap;
130 DenseMap<const LandingPadInst *, LandingPadMap> LPadMaps;
131 SmallPtrSet<BasicBlock *, 4> NormalBlocks;
132 SmallPtrSet<BasicBlock *, 4> EHBlocks;
133 SetVector<BasicBlock *> EHReturnBlocks;
135 // This maps landing pad instructions found in outlined handlers to
136 // the landing pad instruction in the parent function from which they
137 // were cloned. The cloned/nested landing pad is used as the key
138 // because the landing pad may be cloned into multiple handlers.
139 // This map will be used to add the llvm.eh.actions call to the nested
140 // landing pads after all handlers have been outlined.
141 DenseMap<LandingPadInst *, const LandingPadInst *> NestedLPtoOriginalLP;
143 // This maps blocks in the parent function which are destinations of
144 // catch handlers to cloned blocks in (other) outlined handlers. This
145 // handles the case where a nested landing pads has a catch handler that
146 // returns to a handler function rather than the parent function.
147 // The original block is used as the key here because there should only
148 // ever be one handler function from which the cloned block is not pruned.
149 // The original block will be pruned from the parent function after all
150 // handlers have been outlined. This map will be used to adjust the
151 // return instructions of handlers which return to the block that was
152 // outlined into a handler. This is done after all handlers have been
153 // outlined but before the outlined code is pruned from the parent function.
154 DenseMap<const BasicBlock *, BasicBlock *> LPadTargetBlocks;
156 // Map from outlined handler to call to llvm.frameaddress(1). Only used for
158 DenseMap<Function *, Value *> HandlerToParentFP;
160 AllocaInst *SEHExceptionCodeSlot = nullptr;
163 class WinEHFrameVariableMaterializer : public ValueMaterializer {
165 WinEHFrameVariableMaterializer(Function *OutlinedFn, Value *ParentFP,
166 FrameVarInfoMap &FrameVarInfo);
167 ~WinEHFrameVariableMaterializer() override {}
169 Value *materializeValueFor(Value *V) override;
171 void escapeCatchObject(Value *V);
174 FrameVarInfoMap &FrameVarInfo;
178 class LandingPadMap {
180 LandingPadMap() : OriginLPad(nullptr) {}
181 void mapLandingPad(const LandingPadInst *LPad);
183 bool isInitialized() { return OriginLPad != nullptr; }
185 bool isOriginLandingPadBlock(const BasicBlock *BB) const;
186 bool isLandingPadSpecificInst(const Instruction *Inst) const;
188 void remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
189 Value *SelectorValue) const;
192 const LandingPadInst *OriginLPad;
193 // We will normally only see one of each of these instructions, but
194 // if more than one occurs for some reason we can handle that.
195 TinyPtrVector<const ExtractValueInst *> ExtractedEHPtrs;
196 TinyPtrVector<const ExtractValueInst *> ExtractedSelectors;
199 class WinEHCloningDirectorBase : public CloningDirector {
201 WinEHCloningDirectorBase(Function *HandlerFn, Value *ParentFP,
202 FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
203 : Materializer(HandlerFn, ParentFP, VarInfo),
204 SelectorIDType(Type::getInt32Ty(HandlerFn->getContext())),
205 Int8PtrType(Type::getInt8PtrTy(HandlerFn->getContext())),
206 LPadMap(LPadMap), ParentFP(ParentFP) {}
208 CloningAction handleInstruction(ValueToValueMapTy &VMap,
209 const Instruction *Inst,
210 BasicBlock *NewBB) override;
212 virtual CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
213 const Instruction *Inst,
214 BasicBlock *NewBB) = 0;
215 virtual CloningAction handleEndCatch(ValueToValueMapTy &VMap,
216 const Instruction *Inst,
217 BasicBlock *NewBB) = 0;
218 virtual CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
219 const Instruction *Inst,
220 BasicBlock *NewBB) = 0;
221 virtual CloningAction handleIndirectBr(ValueToValueMapTy &VMap,
222 const IndirectBrInst *IBr,
223 BasicBlock *NewBB) = 0;
224 virtual CloningAction handleInvoke(ValueToValueMapTy &VMap,
225 const InvokeInst *Invoke,
226 BasicBlock *NewBB) = 0;
227 virtual CloningAction handleResume(ValueToValueMapTy &VMap,
228 const ResumeInst *Resume,
229 BasicBlock *NewBB) = 0;
230 virtual CloningAction handleCompare(ValueToValueMapTy &VMap,
231 const CmpInst *Compare,
232 BasicBlock *NewBB) = 0;
233 virtual CloningAction handleLandingPad(ValueToValueMapTy &VMap,
234 const LandingPadInst *LPad,
235 BasicBlock *NewBB) = 0;
237 ValueMaterializer *getValueMaterializer() override { return &Materializer; }
240 WinEHFrameVariableMaterializer Materializer;
241 Type *SelectorIDType;
243 LandingPadMap &LPadMap;
245 /// The value representing the parent frame pointer.
249 class WinEHCatchDirector : public WinEHCloningDirectorBase {
252 Function *CatchFn, Value *ParentFP, Value *Selector,
253 FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap,
254 DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPads,
255 DominatorTree *DT, SmallPtrSetImpl<BasicBlock *> &EHBlocks)
256 : WinEHCloningDirectorBase(CatchFn, ParentFP, VarInfo, LPadMap),
257 CurrentSelector(Selector->stripPointerCasts()),
258 ExceptionObjectVar(nullptr), NestedLPtoOriginalLP(NestedLPads),
259 DT(DT), EHBlocks(EHBlocks) {}
261 CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
262 const Instruction *Inst,
263 BasicBlock *NewBB) override;
264 CloningAction handleEndCatch(ValueToValueMapTy &VMap, const Instruction *Inst,
265 BasicBlock *NewBB) override;
266 CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
267 const Instruction *Inst,
268 BasicBlock *NewBB) override;
269 CloningAction handleIndirectBr(ValueToValueMapTy &VMap,
270 const IndirectBrInst *IBr,
271 BasicBlock *NewBB) override;
272 CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
273 BasicBlock *NewBB) override;
274 CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
275 BasicBlock *NewBB) override;
276 CloningAction handleCompare(ValueToValueMapTy &VMap, const CmpInst *Compare,
277 BasicBlock *NewBB) override;
278 CloningAction handleLandingPad(ValueToValueMapTy &VMap,
279 const LandingPadInst *LPad,
280 BasicBlock *NewBB) override;
282 Value *getExceptionVar() { return ExceptionObjectVar; }
283 TinyPtrVector<BasicBlock *> &getReturnTargets() { return ReturnTargets; }
286 Value *CurrentSelector;
288 Value *ExceptionObjectVar;
289 TinyPtrVector<BasicBlock *> ReturnTargets;
291 // This will be a reference to the field of the same name in the WinEHPrepare
292 // object which instantiates this WinEHCatchDirector object.
293 DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPtoOriginalLP;
295 SmallPtrSetImpl<BasicBlock *> &EHBlocks;
298 class WinEHCleanupDirector : public WinEHCloningDirectorBase {
300 WinEHCleanupDirector(Function *CleanupFn, Value *ParentFP,
301 FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
302 : WinEHCloningDirectorBase(CleanupFn, ParentFP, VarInfo,
305 CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
306 const Instruction *Inst,
307 BasicBlock *NewBB) override;
308 CloningAction handleEndCatch(ValueToValueMapTy &VMap, const Instruction *Inst,
309 BasicBlock *NewBB) override;
310 CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
311 const Instruction *Inst,
312 BasicBlock *NewBB) override;
313 CloningAction handleIndirectBr(ValueToValueMapTy &VMap,
314 const IndirectBrInst *IBr,
315 BasicBlock *NewBB) override;
316 CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
317 BasicBlock *NewBB) override;
318 CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
319 BasicBlock *NewBB) override;
320 CloningAction handleCompare(ValueToValueMapTy &VMap, const CmpInst *Compare,
321 BasicBlock *NewBB) override;
322 CloningAction handleLandingPad(ValueToValueMapTy &VMap,
323 const LandingPadInst *LPad,
324 BasicBlock *NewBB) override;
327 class LandingPadActions {
329 LandingPadActions() : HasCleanupHandlers(false) {}
331 void insertCatchHandler(CatchHandler *Action) { Actions.push_back(Action); }
332 void insertCleanupHandler(CleanupHandler *Action) {
333 Actions.push_back(Action);
334 HasCleanupHandlers = true;
337 bool includesCleanup() const { return HasCleanupHandlers; }
339 SmallVectorImpl<ActionHandler *> &actions() { return Actions; }
340 SmallVectorImpl<ActionHandler *>::iterator begin() { return Actions.begin(); }
341 SmallVectorImpl<ActionHandler *>::iterator end() { return Actions.end(); }
344 // Note that this class does not own the ActionHandler objects in this vector.
345 // The ActionHandlers are owned by the CatchHandlerMap and CleanupHandlerMap
346 // in the WinEHPrepare class.
347 SmallVector<ActionHandler *, 4> Actions;
348 bool HasCleanupHandlers;
351 } // end anonymous namespace
353 char WinEHPrepare::ID = 0;
354 INITIALIZE_TM_PASS(WinEHPrepare, "winehprepare", "Prepare Windows exceptions",
357 FunctionPass *llvm::createWinEHPass(const TargetMachine *TM) {
358 return new WinEHPrepare(TM);
361 bool WinEHPrepare::runOnFunction(Function &Fn) {
362 // No need to prepare outlined handlers.
363 if (Fn.hasFnAttribute("wineh-parent"))
366 SmallVector<LandingPadInst *, 4> LPads;
367 SmallVector<ResumeInst *, 4> Resumes;
368 for (BasicBlock &BB : Fn) {
369 if (auto *LP = BB.getLandingPadInst())
371 if (auto *Resume = dyn_cast<ResumeInst>(BB.getTerminator()))
372 Resumes.push_back(Resume);
375 // No need to prepare functions that lack landing pads.
379 // Classify the personality to see what kind of preparation we need.
380 Personality = classifyEHPersonality(LPads.back()->getPersonalityFn());
382 // Do nothing if this is not an MSVC personality.
383 if (!isMSVCEHPersonality(Personality))
386 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
388 // If there were any landing pads, prepareExceptionHandlers will make changes.
389 prepareExceptionHandlers(Fn, LPads);
393 bool WinEHPrepare::doFinalization(Module &M) { return false; }
395 void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {
396 AU.addRequired<DominatorTreeWrapperPass>();
399 static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler,
400 Constant *&Selector, BasicBlock *&NextBB);
402 // Finds blocks reachable from the starting set Worklist. Does not follow unwind
403 // edges or blocks listed in StopPoints.
404 static void findReachableBlocks(SmallPtrSetImpl<BasicBlock *> &ReachableBBs,
405 SetVector<BasicBlock *> &Worklist,
406 const SetVector<BasicBlock *> *StopPoints) {
407 while (!Worklist.empty()) {
408 BasicBlock *BB = Worklist.pop_back_val();
410 // Don't cross blocks that we should stop at.
411 if (StopPoints && StopPoints->count(BB))
414 if (!ReachableBBs.insert(BB).second)
415 continue; // Already visited.
417 // Don't follow unwind edges of invokes.
418 if (auto *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
419 Worklist.insert(II->getNormalDest());
423 // Otherwise, follow all successors.
424 Worklist.insert(succ_begin(BB), succ_end(BB));
428 // Attempt to find an instruction where a block can be split before
429 // a call to llvm.eh.begincatch and its operands. If the block
430 // begins with the begincatch call or one of its adjacent operands
431 // the block will not be split.
432 static Instruction *findBeginCatchSplitPoint(BasicBlock *BB,
434 // If the begincatch call is already the first instruction in the block,
436 Instruction *FirstNonPHI = BB->getFirstNonPHI();
437 if (II == FirstNonPHI)
440 // If either operand is in the same basic block as the instruction and
441 // isn't used by another instruction before the begincatch call, include it
442 // in the split block.
443 auto *Op0 = dyn_cast<Instruction>(II->getOperand(0));
444 auto *Op1 = dyn_cast<Instruction>(II->getOperand(1));
446 Instruction *I = II->getPrevNode();
447 Instruction *LastI = II;
449 while (I == Op0 || I == Op1) {
450 // If the block begins with one of the operands and there are no other
451 // instructions between the operand and the begincatch call, don't split.
452 if (I == FirstNonPHI)
456 I = I->getPrevNode();
459 // If there is at least one instruction in the block before the begincatch
460 // call and its operands, split the block at either the begincatch or
465 /// Find all points where exceptional control rejoins normal control flow via
466 /// llvm.eh.endcatch. Add them to the normal bb reachability worklist.
467 void WinEHPrepare::findCXXEHReturnPoints(
468 Function &F, SetVector<BasicBlock *> &EHReturnBlocks) {
469 for (auto BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) {
470 BasicBlock *BB = BBI;
471 for (Instruction &I : *BB) {
472 if (match(&I, m_Intrinsic<Intrinsic::eh_begincatch>())) {
473 Instruction *SplitPt =
474 findBeginCatchSplitPoint(BB, cast<IntrinsicInst>(&I));
476 // Split the block before the llvm.eh.begincatch call to allow
477 // cleanup and catch code to be distinguished later.
478 // Do not update BBI because we still need to process the
479 // portion of the block that we are splitting off.
480 SplitBlock(BB, SplitPt, DT);
484 if (match(&I, m_Intrinsic<Intrinsic::eh_endcatch>())) {
485 // Split the block after the call to llvm.eh.endcatch if there is
486 // anything other than an unconditional branch, or if the successor
487 // starts with a phi.
488 auto *Br = dyn_cast<BranchInst>(I.getNextNode());
489 if (!Br || !Br->isUnconditional() ||
490 isa<PHINode>(Br->getSuccessor(0)->begin())) {
491 DEBUG(dbgs() << "splitting block " << BB->getName()
492 << " with llvm.eh.endcatch\n");
493 BBI = SplitBlock(BB, I.getNextNode(), DT);
495 // The next BB is normal control flow.
496 EHReturnBlocks.insert(BB->getTerminator()->getSuccessor(0));
503 static bool isCatchAllLandingPad(const BasicBlock *BB) {
504 const LandingPadInst *LP = BB->getLandingPadInst();
507 unsigned N = LP->getNumClauses();
508 return (N > 0 && LP->isCatch(N - 1) &&
509 isa<ConstantPointerNull>(LP->getClause(N - 1)));
512 /// Find all points where exceptions control rejoins normal control flow via
513 /// selector dispatch.
514 void WinEHPrepare::findSEHEHReturnPoints(
515 Function &F, SetVector<BasicBlock *> &EHReturnBlocks) {
516 for (auto BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) {
517 BasicBlock *BB = BBI;
518 // If the landingpad is a catch-all, treat the whole lpad as if it is
519 // reachable from normal control flow.
520 // FIXME: This is imprecise. We need a better way of identifying where a
521 // catch-all starts and cleanups stop. As far as LLVM is concerned, there
523 if (isCatchAllLandingPad(BB)) {
524 EHReturnBlocks.insert(BB);
528 BasicBlock *CatchHandler;
531 if (isSelectorDispatch(BB, CatchHandler, Selector, NextBB)) {
532 // Split the edge if there is a phi node. Returning from EH to a phi node
533 // is just as impossible as having a phi after an indirectbr.
534 if (isa<PHINode>(CatchHandler->begin())) {
535 DEBUG(dbgs() << "splitting EH return edge from " << BB->getName()
536 << " to " << CatchHandler->getName() << '\n');
537 BBI = CatchHandler = SplitCriticalEdge(
538 BB, std::find(succ_begin(BB), succ_end(BB), CatchHandler));
540 EHReturnBlocks.insert(CatchHandler);
545 void WinEHPrepare::identifyEHBlocks(Function &F,
546 SmallVectorImpl<LandingPadInst *> &LPads) {
547 DEBUG(dbgs() << "Demoting values live across exception handlers in function "
548 << F.getName() << '\n');
550 // Build a set of all non-exceptional blocks and exceptional blocks.
551 // - Non-exceptional blocks are blocks reachable from the entry block while
552 // not following invoke unwind edges.
553 // - Exceptional blocks are blocks reachable from landingpads. Analysis does
554 // not follow llvm.eh.endcatch blocks, which mark a transition from
555 // exceptional to normal control.
557 if (Personality == EHPersonality::MSVC_CXX)
558 findCXXEHReturnPoints(F, EHReturnBlocks);
560 findSEHEHReturnPoints(F, EHReturnBlocks);
563 dbgs() << "identified the following blocks as EH return points:\n";
564 for (BasicBlock *BB : EHReturnBlocks)
565 dbgs() << " " << BB->getName() << '\n';
568 // Join points should not have phis at this point, unless they are a
569 // landingpad, in which case we will demote their phis later.
571 for (BasicBlock *BB : EHReturnBlocks)
572 assert((BB->isLandingPad() || !isa<PHINode>(BB->begin())) &&
573 "non-lpad EH return block has phi");
576 // Normal blocks are the blocks reachable from the entry block and all EH
578 SetVector<BasicBlock *> Worklist;
579 Worklist = EHReturnBlocks;
580 Worklist.insert(&F.getEntryBlock());
581 findReachableBlocks(NormalBlocks, Worklist, nullptr);
583 dbgs() << "marked the following blocks as normal:\n";
584 for (BasicBlock *BB : NormalBlocks)
585 dbgs() << " " << BB->getName() << '\n';
588 // Exceptional blocks are the blocks reachable from landingpads that don't
589 // cross EH return points.
591 for (auto *LPI : LPads)
592 Worklist.insert(LPI->getParent());
593 findReachableBlocks(EHBlocks, Worklist, &EHReturnBlocks);
595 dbgs() << "marked the following blocks as exceptional:\n";
596 for (BasicBlock *BB : EHBlocks)
597 dbgs() << " " << BB->getName() << '\n';
602 /// Ensure that all values live into and out of exception handlers are stored
604 /// FIXME: This falls down when values are defined in one handler and live into
605 /// another handler. For example, a cleanup defines a value used only by a
607 void WinEHPrepare::demoteValuesLiveAcrossHandlers(
608 Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
609 DEBUG(dbgs() << "Demoting values live across exception handlers in function "
610 << F.getName() << '\n');
612 // identifyEHBlocks() should have been called before this function.
613 assert(!NormalBlocks.empty());
615 SetVector<Argument *> ArgsToDemote;
616 SetVector<Instruction *> InstrsToDemote;
617 for (BasicBlock &BB : F) {
618 bool IsNormalBB = NormalBlocks.count(&BB);
619 bool IsEHBB = EHBlocks.count(&BB);
620 if (!IsNormalBB && !IsEHBB)
621 continue; // Blocks that are neither normal nor EH are unreachable.
622 for (Instruction &I : BB) {
623 for (Value *Op : I.operands()) {
624 // Don't demote static allocas, constants, and labels.
625 if (isa<Constant>(Op) || isa<BasicBlock>(Op) || isa<InlineAsm>(Op))
627 auto *AI = dyn_cast<AllocaInst>(Op);
628 if (AI && AI->isStaticAlloca())
631 if (auto *Arg = dyn_cast<Argument>(Op)) {
633 DEBUG(dbgs() << "Demoting argument " << *Arg
634 << " used by EH instr: " << I << "\n");
635 ArgsToDemote.insert(Arg);
640 auto *OpI = cast<Instruction>(Op);
641 BasicBlock *OpBB = OpI->getParent();
642 // If a value is produced and consumed in the same BB, we don't need to
646 bool IsOpNormalBB = NormalBlocks.count(OpBB);
647 bool IsOpEHBB = EHBlocks.count(OpBB);
648 if (IsNormalBB != IsOpNormalBB || IsEHBB != IsOpEHBB) {
650 dbgs() << "Demoting instruction live in-out from EH:\n";
651 dbgs() << "Instr: " << *OpI << '\n';
652 dbgs() << "User: " << I << '\n';
654 InstrsToDemote.insert(OpI);
660 // Demote values live into and out of handlers.
661 // FIXME: This demotion is inefficient. We should insert spills at the point
662 // of definition, insert one reload in each handler that uses the value, and
663 // insert reloads in the BB used to rejoin normal control flow.
664 Instruction *AllocaInsertPt = F.getEntryBlock().getFirstInsertionPt();
665 for (Instruction *I : InstrsToDemote)
666 DemoteRegToStack(*I, false, AllocaInsertPt);
668 // Demote arguments separately, and only for uses in EH blocks.
669 for (Argument *Arg : ArgsToDemote) {
670 auto *Slot = new AllocaInst(Arg->getType(), nullptr,
671 Arg->getName() + ".reg2mem", AllocaInsertPt);
672 SmallVector<User *, 4> Users(Arg->user_begin(), Arg->user_end());
673 for (User *U : Users) {
674 auto *I = dyn_cast<Instruction>(U);
675 if (I && EHBlocks.count(I->getParent())) {
676 auto *Reload = new LoadInst(Slot, Arg->getName() + ".reload", false, I);
677 U->replaceUsesOfWith(Arg, Reload);
680 new StoreInst(Arg, Slot, AllocaInsertPt);
683 // Demote landingpad phis, as the landingpad will be removed from the machine
685 for (LandingPadInst *LPI : LPads) {
686 BasicBlock *BB = LPI->getParent();
687 while (auto *Phi = dyn_cast<PHINode>(BB->begin()))
688 DemotePHIToStack(Phi, AllocaInsertPt);
691 DEBUG(dbgs() << "Demoted " << InstrsToDemote.size() << " instructions and "
692 << ArgsToDemote.size() << " arguments for WinEHPrepare\n\n");
695 bool WinEHPrepare::prepareExceptionHandlers(
696 Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
697 // Don't run on functions that are already prepared.
698 for (LandingPadInst *LPad : LPads) {
699 BasicBlock *LPadBB = LPad->getParent();
700 for (Instruction &Inst : *LPadBB)
701 if (match(&Inst, m_Intrinsic<Intrinsic::eh_actions>()))
705 identifyEHBlocks(F, LPads);
706 demoteValuesLiveAcrossHandlers(F, LPads);
708 // These containers are used to re-map frame variables that are used in
709 // outlined catch and cleanup handlers. They will be populated as the
710 // handlers are outlined.
711 FrameVarInfoMap FrameVarInfo;
713 bool HandlersOutlined = false;
715 Module *M = F.getParent();
716 LLVMContext &Context = M->getContext();
718 // Create a new function to receive the handler contents.
719 PointerType *Int8PtrType = Type::getInt8PtrTy(Context);
720 Type *Int32Type = Type::getInt32Ty(Context);
721 Function *ActionIntrin = Intrinsic::getDeclaration(M, Intrinsic::eh_actions);
723 if (isAsynchronousEHPersonality(Personality)) {
724 // FIXME: Switch the ehptr type to i32 and then switch this.
725 SEHExceptionCodeSlot =
726 new AllocaInst(Int8PtrType, nullptr, "seh_exception_code",
727 F.getEntryBlock().getFirstInsertionPt());
730 // In order to handle the case where one outlined catch handler returns
731 // to a block within another outlined catch handler that would otherwise
732 // be unreachable, we need to outline the nested landing pad before we
733 // outline the landing pad which encloses it.
734 if (!isAsynchronousEHPersonality(Personality))
735 std::sort(LPads.begin(), LPads.end(),
736 [this](LandingPadInst *const &L, LandingPadInst *const &R) {
737 return DT->properlyDominates(R->getParent(), L->getParent());
740 // This container stores the llvm.eh.recover and IndirectBr instructions
741 // that make up the body of each landing pad after it has been outlined.
742 // We need to defer the population of the target list for the indirectbr
743 // until all landing pads have been outlined so that we can handle the
744 // case of blocks in the target that are reached only from nested
746 SmallVector<std::pair<CallInst*, IndirectBrInst *>, 4> LPadImpls;
748 for (LandingPadInst *LPad : LPads) {
749 // Look for evidence that this landingpad has already been processed.
750 bool LPadHasActionList = false;
751 BasicBlock *LPadBB = LPad->getParent();
752 for (Instruction &Inst : *LPadBB) {
753 if (match(&Inst, m_Intrinsic<Intrinsic::eh_actions>())) {
754 LPadHasActionList = true;
759 // If we've already outlined the handlers for this landingpad,
760 // there's nothing more to do here.
761 if (LPadHasActionList)
764 // If either of the values in the aggregate returned by the landing pad is
765 // extracted and stored to memory, promote the stored value to a register.
766 promoteLandingPadValues(LPad);
768 LandingPadActions Actions;
769 mapLandingPadBlocks(LPad, Actions);
771 HandlersOutlined |= !Actions.actions().empty();
772 for (ActionHandler *Action : Actions) {
773 if (Action->hasBeenProcessed())
775 BasicBlock *StartBB = Action->getStartBlock();
777 // SEH doesn't do any outlining for catches. Instead, pass the handler
778 // basic block addr to llvm.eh.actions and list the block as a return
780 if (isAsynchronousEHPersonality(Personality)) {
781 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
782 processSEHCatchHandler(CatchAction, StartBB);
787 outlineHandler(Action, &F, LPad, StartBB, FrameVarInfo);
790 // Split the block after the landingpad instruction so that it is just a
791 // call to llvm.eh.actions followed by indirectbr.
792 assert(!isa<PHINode>(LPadBB->begin()) && "lpad phi not removed");
793 SplitBlock(LPadBB, LPad->getNextNode(), DT);
794 // Erase the branch inserted by the split so we can insert indirectbr.
795 LPadBB->getTerminator()->eraseFromParent();
797 // Replace all extracted values with undef and ultimately replace the
798 // landingpad with undef.
799 SmallVector<Instruction *, 4> SEHCodeUses;
800 SmallVector<Instruction *, 4> EHUndefs;
801 for (User *U : LPad->users()) {
802 auto *E = dyn_cast<ExtractValueInst>(U);
805 assert(E->getNumIndices() == 1 &&
806 "Unexpected operation: extracting both landing pad values");
807 unsigned Idx = *E->idx_begin();
808 assert((Idx == 0 || Idx == 1) && "unexpected index");
809 if (Idx == 0 && isAsynchronousEHPersonality(Personality))
810 SEHCodeUses.push_back(E);
812 EHUndefs.push_back(E);
814 for (Instruction *E : EHUndefs) {
815 E->replaceAllUsesWith(UndefValue::get(E->getType()));
816 E->eraseFromParent();
818 LPad->replaceAllUsesWith(UndefValue::get(LPad->getType()));
820 // Rewrite uses of the exception pointer to loads of an alloca.
821 for (Instruction *E : SEHCodeUses) {
822 SmallVector<Use *, 4> Uses;
823 for (Use &U : E->uses())
825 for (Use *U : Uses) {
826 auto *I = cast<Instruction>(U->getUser());
827 if (isa<ResumeInst>(I))
830 if (auto *Phi = dyn_cast<PHINode>(I))
831 LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false,
832 Phi->getIncomingBlock(*U));
834 LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false, I);
837 E->replaceAllUsesWith(UndefValue::get(E->getType()));
838 E->eraseFromParent();
841 // Add a call to describe the actions for this landing pad.
842 std::vector<Value *> ActionArgs;
843 for (ActionHandler *Action : Actions) {
844 // Action codes from docs are: 0 cleanup, 1 catch.
845 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
846 ActionArgs.push_back(ConstantInt::get(Int32Type, 1));
847 ActionArgs.push_back(CatchAction->getSelector());
848 // Find the frame escape index of the exception object alloca in the
850 int FrameEscapeIdx = -1;
851 Value *EHObj = const_cast<Value *>(CatchAction->getExceptionVar());
852 if (EHObj && !isa<ConstantPointerNull>(EHObj)) {
853 auto I = FrameVarInfo.find(EHObj);
854 assert(I != FrameVarInfo.end() &&
855 "failed to map llvm.eh.begincatch var");
856 FrameEscapeIdx = std::distance(FrameVarInfo.begin(), I);
858 ActionArgs.push_back(ConstantInt::get(Int32Type, FrameEscapeIdx));
860 ActionArgs.push_back(ConstantInt::get(Int32Type, 0));
862 ActionArgs.push_back(Action->getHandlerBlockOrFunc());
865 CallInst::Create(ActionIntrin, ActionArgs, "recover", LPadBB);
867 SetVector<BasicBlock *> ReturnTargets;
868 for (ActionHandler *Action : Actions) {
869 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
870 const auto &CatchTargets = CatchAction->getReturnTargets();
871 ReturnTargets.insert(CatchTargets.begin(), CatchTargets.end());
874 IndirectBrInst *Branch =
875 IndirectBrInst::Create(Recover, ReturnTargets.size(), LPadBB);
876 for (BasicBlock *Target : ReturnTargets)
877 Branch->addDestination(Target);
879 if (!isAsynchronousEHPersonality(Personality)) {
880 // C++ EH must repopulate the targets later to handle the case of
881 // targets that are reached indirectly through nested landing pads.
882 LPadImpls.push_back(std::make_pair(Recover, Branch));
885 } // End for each landingpad
887 // If nothing got outlined, there is no more processing to be done.
888 if (!HandlersOutlined)
891 // Replace any nested landing pad stubs with the correct action handler.
892 // This must be done before we remove unreachable blocks because it
893 // cleans up references to outlined blocks that will be deleted.
894 for (auto &LPadPair : NestedLPtoOriginalLP)
895 completeNestedLandingPad(&F, LPadPair.first, LPadPair.second, FrameVarInfo);
896 NestedLPtoOriginalLP.clear();
898 // Update the indirectbr instructions' target lists if necessary.
899 SetVector<BasicBlock*> CheckedTargets;
900 SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList;
901 for (auto &LPadImplPair : LPadImpls) {
902 IntrinsicInst *Recover = cast<IntrinsicInst>(LPadImplPair.first);
903 IndirectBrInst *Branch = LPadImplPair.second;
905 // Get a list of handlers called by
906 parseEHActions(Recover, ActionList);
908 // Add an indirect branch listing possible successors of the catch handlers.
909 SetVector<BasicBlock *> ReturnTargets;
910 for (const auto &Action : ActionList) {
911 if (auto *CA = dyn_cast<CatchHandler>(Action.get())) {
912 Function *Handler = cast<Function>(CA->getHandlerBlockOrFunc());
913 getPossibleReturnTargets(&F, Handler, ReturnTargets);
917 // Clear any targets we already knew about.
918 for (unsigned int I = 0, E = Branch->getNumDestinations(); I < E; ++I) {
919 BasicBlock *KnownTarget = Branch->getDestination(I);
920 if (ReturnTargets.count(KnownTarget))
921 ReturnTargets.remove(KnownTarget);
923 for (BasicBlock *Target : ReturnTargets) {
924 Branch->addDestination(Target);
925 // The target may be a block that we excepted to get pruned.
926 // If it is, it may contain a call to llvm.eh.endcatch.
927 if (CheckedTargets.insert(Target)) {
928 // Earlier preparations guarantee that all calls to llvm.eh.endcatch
929 // will be followed by an unconditional branch.
930 auto *Br = dyn_cast<BranchInst>(Target->getTerminator());
931 if (Br && Br->isUnconditional() &&
932 Br != Target->getFirstNonPHIOrDbgOrLifetime()) {
933 Instruction *Prev = Br->getPrevNode();
934 if (match(cast<Value>(Prev), m_Intrinsic<Intrinsic::eh_endcatch>()))
935 Prev->eraseFromParent();
942 F.addFnAttr("wineh-parent", F.getName());
944 // Delete any blocks that were only used by handlers that were outlined above.
945 removeUnreachableBlocks(F);
947 BasicBlock *Entry = &F.getEntryBlock();
948 IRBuilder<> Builder(F.getParent()->getContext());
949 Builder.SetInsertPoint(Entry->getFirstInsertionPt());
951 Function *FrameEscapeFn =
952 Intrinsic::getDeclaration(M, Intrinsic::frameescape);
953 Function *RecoverFrameFn =
954 Intrinsic::getDeclaration(M, Intrinsic::framerecover);
955 SmallVector<Value *, 8> AllocasToEscape;
957 // Scan the entry block for an existing call to llvm.frameescape. We need to
958 // keep escaping those objects.
959 for (Instruction &I : F.front()) {
960 auto *II = dyn_cast<IntrinsicInst>(&I);
961 if (II && II->getIntrinsicID() == Intrinsic::frameescape) {
962 auto Args = II->arg_operands();
963 AllocasToEscape.append(Args.begin(), Args.end());
964 II->eraseFromParent();
969 // Finally, replace all of the temporary allocas for frame variables used in
970 // the outlined handlers with calls to llvm.framerecover.
971 for (auto &VarInfoEntry : FrameVarInfo) {
972 Value *ParentVal = VarInfoEntry.first;
973 TinyPtrVector<AllocaInst *> &Allocas = VarInfoEntry.second;
974 AllocaInst *ParentAlloca = cast<AllocaInst>(ParentVal);
976 // FIXME: We should try to sink unescaped allocas from the parent frame into
977 // the child frame. If the alloca is escaped, we have to use the lifetime
978 // markers to ensure that the alloca is only live within the child frame.
980 // Add this alloca to the list of things to escape.
981 AllocasToEscape.push_back(ParentAlloca);
983 // Next replace all outlined allocas that are mapped to it.
984 for (AllocaInst *TempAlloca : Allocas) {
985 if (TempAlloca == getCatchObjectSentinel())
986 continue; // Skip catch parameter sentinels.
987 Function *HandlerFn = TempAlloca->getParent()->getParent();
988 llvm::Value *FP = HandlerToParentFP[HandlerFn];
991 // FIXME: Sink this framerecover into the blocks where it is used.
992 Builder.SetInsertPoint(TempAlloca);
993 Builder.SetCurrentDebugLocation(TempAlloca->getDebugLoc());
994 Value *RecoverArgs[] = {
995 Builder.CreateBitCast(&F, Int8PtrType, ""), FP,
996 llvm::ConstantInt::get(Int32Type, AllocasToEscape.size() - 1)};
997 Instruction *RecoveredAlloca =
998 Builder.CreateCall(RecoverFrameFn, RecoverArgs);
1000 // Add a pointer bitcast if the alloca wasn't an i8.
1001 if (RecoveredAlloca->getType() != TempAlloca->getType()) {
1002 RecoveredAlloca->setName(Twine(TempAlloca->getName()) + ".i8");
1003 RecoveredAlloca = cast<Instruction>(
1004 Builder.CreateBitCast(RecoveredAlloca, TempAlloca->getType()));
1006 TempAlloca->replaceAllUsesWith(RecoveredAlloca);
1007 TempAlloca->removeFromParent();
1008 RecoveredAlloca->takeName(TempAlloca);
1011 } // End for each FrameVarInfo entry.
1013 // Insert 'call void (...)* @llvm.frameescape(...)' at the end of the entry
1015 Builder.SetInsertPoint(&F.getEntryBlock().back());
1016 Builder.CreateCall(FrameEscapeFn, AllocasToEscape);
1018 if (SEHExceptionCodeSlot) {
1019 if (SEHExceptionCodeSlot->hasNUses(0))
1020 SEHExceptionCodeSlot->eraseFromParent();
1021 else if (isAllocaPromotable(SEHExceptionCodeSlot))
1022 PromoteMemToReg(SEHExceptionCodeSlot, *DT);
1025 // Clean up the handler action maps we created for this function
1026 DeleteContainerSeconds(CatchHandlerMap);
1027 CatchHandlerMap.clear();
1028 DeleteContainerSeconds(CleanupHandlerMap);
1029 CleanupHandlerMap.clear();
1030 HandlerToParentFP.clear();
1032 SEHExceptionCodeSlot = nullptr;
1034 NormalBlocks.clear();
1035 EHReturnBlocks.clear();
1037 return HandlersOutlined;
1040 void WinEHPrepare::promoteLandingPadValues(LandingPadInst *LPad) {
1041 // If the return values of the landing pad instruction are extracted and
1042 // stored to memory, we want to promote the store locations to reg values.
1043 SmallVector<AllocaInst *, 2> EHAllocas;
1045 // The landingpad instruction returns an aggregate value. Typically, its
1046 // value will be passed to a pair of extract value instructions and the
1047 // results of those extracts are often passed to store instructions.
1048 // In unoptimized code the stored value will often be loaded and then stored
1050 for (auto *U : LPad->users()) {
1051 ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
1055 for (auto *EU : Extract->users()) {
1056 if (auto *Store = dyn_cast<StoreInst>(EU)) {
1057 auto *AV = cast<AllocaInst>(Store->getPointerOperand());
1058 EHAllocas.push_back(AV);
1063 // We can't do this without a dominator tree.
1066 if (!EHAllocas.empty()) {
1067 PromoteMemToReg(EHAllocas, *DT);
1071 // After promotion, some extracts may be trivially dead. Remove them.
1072 SmallVector<Value *, 4> Users(LPad->user_begin(), LPad->user_end());
1073 for (auto *U : Users)
1074 RecursivelyDeleteTriviallyDeadInstructions(U);
1077 void WinEHPrepare::getPossibleReturnTargets(Function *ParentF,
1079 SetVector<BasicBlock*> &Targets) {
1080 for (BasicBlock &BB : *HandlerF) {
1081 // If the handler contains landing pads, check for any
1082 // handlers that may return directly to a block in the
1084 if (auto *LPI = BB.getLandingPadInst()) {
1085 IntrinsicInst *Recover = cast<IntrinsicInst>(LPI->getNextNode());
1086 SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList;
1087 parseEHActions(Recover, ActionList);
1088 for (const auto &Action : ActionList) {
1089 if (auto *CH = dyn_cast<CatchHandler>(Action.get())) {
1090 Function *NestedF = cast<Function>(CH->getHandlerBlockOrFunc());
1091 getPossibleReturnTargets(ParentF, NestedF, Targets);
1096 auto *Ret = dyn_cast<ReturnInst>(BB.getTerminator());
1100 // Handler functions must always return a block address.
1101 BlockAddress *BA = cast<BlockAddress>(Ret->getReturnValue());
1103 // If this is the handler for a nested landing pad, the
1104 // return address may have been remapped to a block in the
1105 // parent handler. We're not interested in those.
1106 if (BA->getFunction() != ParentF)
1109 Targets.insert(BA->getBasicBlock());
1113 void WinEHPrepare::completeNestedLandingPad(Function *ParentFn,
1114 LandingPadInst *OutlinedLPad,
1115 const LandingPadInst *OriginalLPad,
1116 FrameVarInfoMap &FrameVarInfo) {
1117 // Get the nested block and erase the unreachable instruction that was
1118 // temporarily inserted as its terminator.
1119 LLVMContext &Context = ParentFn->getContext();
1120 BasicBlock *OutlinedBB = OutlinedLPad->getParent();
1121 // If the nested landing pad was outlined before the landing pad that enclosed
1122 // it, it will already be in outlined form. In that case, we just need to see
1123 // if the returns and the enclosing branch instruction need to be updated.
1124 IndirectBrInst *Branch =
1125 dyn_cast<IndirectBrInst>(OutlinedBB->getTerminator());
1127 // If the landing pad wasn't in outlined form, it should be a stub with
1128 // an unreachable terminator.
1129 assert(isa<UnreachableInst>(OutlinedBB->getTerminator()));
1130 OutlinedBB->getTerminator()->eraseFromParent();
1131 // That should leave OutlinedLPad as the last instruction in its block.
1132 assert(&OutlinedBB->back() == OutlinedLPad);
1135 // The original landing pad will have already had its action intrinsic
1136 // built by the outlining loop. We need to clone that into the outlined
1137 // location. It may also be necessary to add references to the exception
1138 // variables to the outlined handler in which this landing pad is nested
1139 // and remap return instructions in the nested handlers that should return
1140 // to an address in the outlined handler.
1141 Function *OutlinedHandlerFn = OutlinedBB->getParent();
1142 BasicBlock::const_iterator II = OriginalLPad;
1144 // The instruction after the landing pad should now be a call to eh.actions.
1145 const Instruction *Recover = II;
1146 assert(match(Recover, m_Intrinsic<Intrinsic::eh_actions>()));
1147 const IntrinsicInst *EHActions = cast<IntrinsicInst>(Recover);
1149 // Remap the return target in the nested handler.
1150 SmallVector<BlockAddress *, 4> ActionTargets;
1151 SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList;
1152 parseEHActions(EHActions, ActionList);
1153 for (const auto &Action : ActionList) {
1154 auto *Catch = dyn_cast<CatchHandler>(Action.get());
1157 // The dyn_cast to function here selects C++ catch handlers and skips
1158 // SEH catch handlers.
1159 auto *Handler = dyn_cast<Function>(Catch->getHandlerBlockOrFunc());
1162 // Visit all the return instructions, looking for places that return
1163 // to a location within OutlinedHandlerFn.
1164 for (BasicBlock &NestedHandlerBB : *Handler) {
1165 auto *Ret = dyn_cast<ReturnInst>(NestedHandlerBB.getTerminator());
1169 // Handler functions must always return a block address.
1170 BlockAddress *BA = cast<BlockAddress>(Ret->getReturnValue());
1171 // The original target will have been in the main parent function,
1172 // but if it is the address of a block that has been outlined, it
1173 // should be a block that was outlined into OutlinedHandlerFn.
1174 assert(BA->getFunction() == ParentFn);
1176 // Ignore targets that aren't part of an outlined handler function.
1177 if (!LPadTargetBlocks.count(BA->getBasicBlock()))
1180 // If the return value is the address ofF a block that we
1181 // previously outlined into the parent handler function, replace
1182 // the return instruction and add the mapped target to the list
1183 // of possible return addresses.
1184 BasicBlock *MappedBB = LPadTargetBlocks[BA->getBasicBlock()];
1185 assert(MappedBB->getParent() == OutlinedHandlerFn);
1186 BlockAddress *NewBA = BlockAddress::get(OutlinedHandlerFn, MappedBB);
1187 Ret->eraseFromParent();
1188 ReturnInst::Create(Context, NewBA, &NestedHandlerBB);
1189 ActionTargets.push_back(NewBA);
1195 // If the landing pad was already in outlined form, just update its targets.
1196 for (unsigned int I = Branch->getNumDestinations(); I > 0; --I)
1197 Branch->removeDestination(I);
1198 // Add the previously collected action targets.
1199 for (auto *Target : ActionTargets)
1200 Branch->addDestination(Target->getBasicBlock());
1202 // If the landing pad was previously stubbed out, fill in its outlined form.
1203 IntrinsicInst *NewEHActions = cast<IntrinsicInst>(EHActions->clone());
1204 OutlinedBB->getInstList().push_back(NewEHActions);
1206 // Insert an indirect branch into the outlined landing pad BB.
1207 IndirectBrInst *IBr = IndirectBrInst::Create(NewEHActions, 0, OutlinedBB);
1208 // Add the previously collected action targets.
1209 for (auto *Target : ActionTargets)
1210 IBr->addDestination(Target->getBasicBlock());
1214 // This function examines a block to determine whether the block ends with a
1215 // conditional branch to a catch handler based on a selector comparison.
1216 // This function is used both by the WinEHPrepare::findSelectorComparison() and
1217 // WinEHCleanupDirector::handleTypeIdFor().
1218 static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler,
1219 Constant *&Selector, BasicBlock *&NextBB) {
1220 ICmpInst::Predicate Pred;
1221 BasicBlock *TBB, *FBB;
1224 if (!match(BB->getTerminator(),
1225 m_Br(m_ICmp(Pred, m_Value(LHS), m_Value(RHS)), TBB, FBB)))
1229 m_Intrinsic<Intrinsic::eh_typeid_for>(m_Constant(Selector))) &&
1230 !match(RHS, m_Intrinsic<Intrinsic::eh_typeid_for>(m_Constant(Selector))))
1233 if (Pred == CmpInst::ICMP_EQ) {
1239 if (Pred == CmpInst::ICMP_NE) {
1248 static bool isCatchBlock(BasicBlock *BB) {
1249 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
1251 if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_begincatch>()))
1257 static BasicBlock *createStubLandingPad(Function *Handler,
1258 Value *PersonalityFn) {
1259 // FIXME: Finish this!
1260 LLVMContext &Context = Handler->getContext();
1261 BasicBlock *StubBB = BasicBlock::Create(Context, "stub");
1262 Handler->getBasicBlockList().push_back(StubBB);
1263 IRBuilder<> Builder(StubBB);
1264 LandingPadInst *LPad = Builder.CreateLandingPad(
1265 llvm::StructType::get(Type::getInt8PtrTy(Context),
1266 Type::getInt32Ty(Context), nullptr),
1268 // Insert a call to llvm.eh.actions so that we don't try to outline this lpad.
1269 Function *ActionIntrin =
1270 Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::eh_actions);
1271 Builder.CreateCall(ActionIntrin, {}, "recover");
1272 LPad->setCleanup(true);
1273 Builder.CreateUnreachable();
1277 // Cycles through the blocks in an outlined handler function looking for an
1278 // invoke instruction and inserts an invoke of llvm.donothing with an empty
1279 // landing pad if none is found. The code that generates the .xdata tables for
1280 // the handler needs at least one landing pad to identify the parent function's
1282 void WinEHPrepare::addStubInvokeToHandlerIfNeeded(Function *Handler,
1283 Value *PersonalityFn) {
1284 ReturnInst *Ret = nullptr;
1285 UnreachableInst *Unreached = nullptr;
1286 for (BasicBlock &BB : *Handler) {
1287 TerminatorInst *Terminator = BB.getTerminator();
1288 // If we find an invoke, there is nothing to be done.
1289 auto *II = dyn_cast<InvokeInst>(Terminator);
1292 // If we've already recorded a return instruction, keep looking for invokes.
1294 Ret = dyn_cast<ReturnInst>(Terminator);
1295 // If we haven't recorded an unreachable instruction, try this terminator.
1297 Unreached = dyn_cast<UnreachableInst>(Terminator);
1300 // If we got this far, the handler contains no invokes. We should have seen
1301 // at least one return or unreachable instruction. We'll insert an invoke of
1302 // llvm.donothing ahead of that instruction.
1303 assert(Ret || Unreached);
1304 TerminatorInst *Term;
1309 BasicBlock *OldRetBB = Term->getParent();
1310 BasicBlock *NewRetBB = SplitBlock(OldRetBB, Term, DT);
1311 // SplitBlock adds an unconditional branch instruction at the end of the
1312 // parent block. We want to replace that with an invoke call, so we can
1314 OldRetBB->getTerminator()->eraseFromParent();
1315 BasicBlock *StubLandingPad = createStubLandingPad(Handler, PersonalityFn);
1317 Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::donothing);
1318 InvokeInst::Create(F, NewRetBB, StubLandingPad, None, "", OldRetBB);
1321 // FIXME: Consider sinking this into lib/Target/X86 somehow. TargetLowering
1322 // usually doesn't build LLVM IR, so that's probably the wrong place.
1323 Function *WinEHPrepare::createHandlerFunc(Type *RetTy, const Twine &Name,
1324 Module *M, Value *&ParentFP) {
1325 // x64 uses a two-argument prototype where the parent FP is the second
1326 // argument. x86 uses no arguments, just the incoming EBP value.
1327 LLVMContext &Context = M->getContext();
1328 FunctionType *FnType;
1329 if (TheTriple.getArch() == Triple::x86_64) {
1330 Type *Int8PtrType = Type::getInt8PtrTy(Context);
1331 Type *ArgTys[2] = {Int8PtrType, Int8PtrType};
1332 FnType = FunctionType::get(RetTy, ArgTys, false);
1334 FnType = FunctionType::get(RetTy, None, false);
1338 Function::Create(FnType, GlobalVariable::InternalLinkage, Name, M);
1339 BasicBlock *Entry = BasicBlock::Create(Context, "entry");
1340 Handler->getBasicBlockList().push_front(Entry);
1341 if (TheTriple.getArch() == Triple::x86_64) {
1342 ParentFP = &(Handler->getArgumentList().back());
1345 Function *FrameAddressFn =
1346 Intrinsic::getDeclaration(M, Intrinsic::frameaddress);
1347 Value *Args[1] = {ConstantInt::get(Type::getInt32Ty(Context), 1)};
1348 ParentFP = CallInst::Create(FrameAddressFn, Args, "parent_fp",
1349 &Handler->getEntryBlock());
1354 bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn,
1355 LandingPadInst *LPad, BasicBlock *StartBB,
1356 FrameVarInfoMap &VarInfo) {
1357 Module *M = SrcFn->getParent();
1358 LLVMContext &Context = M->getContext();
1359 Type *Int8PtrType = Type::getInt8PtrTy(Context);
1361 // Create a new function to receive the handler contents.
1364 if (Action->getType() == Catch) {
1365 Handler = createHandlerFunc(Int8PtrType, SrcFn->getName() + ".catch", M,
1368 Handler = createHandlerFunc(Type::getVoidTy(Context),
1369 SrcFn->getName() + ".cleanup", M, ParentFP);
1371 HandlerToParentFP[Handler] = ParentFP;
1372 Handler->addFnAttr("wineh-parent", SrcFn->getName());
1373 BasicBlock *Entry = &Handler->getEntryBlock();
1375 // Generate a standard prolog to setup the frame recovery structure.
1376 IRBuilder<> Builder(Context);
1377 Builder.SetInsertPoint(Entry);
1378 Builder.SetCurrentDebugLocation(LPad->getDebugLoc());
1380 std::unique_ptr<WinEHCloningDirectorBase> Director;
1382 ValueToValueMapTy VMap;
1384 LandingPadMap &LPadMap = LPadMaps[LPad];
1385 if (!LPadMap.isInitialized())
1386 LPadMap.mapLandingPad(LPad);
1387 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
1388 Constant *Sel = CatchAction->getSelector();
1389 Director.reset(new WinEHCatchDirector(Handler, ParentFP, Sel, VarInfo,
1390 LPadMap, NestedLPtoOriginalLP, DT,
1392 LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
1393 ConstantInt::get(Type::getInt32Ty(Context), 1));
1396 new WinEHCleanupDirector(Handler, ParentFP, VarInfo, LPadMap));
1397 LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
1398 UndefValue::get(Type::getInt32Ty(Context)));
1401 SmallVector<ReturnInst *, 8> Returns;
1402 ClonedCodeInfo OutlinedFunctionInfo;
1404 // If the start block contains PHI nodes, we need to map them.
1405 BasicBlock::iterator II = StartBB->begin();
1406 while (auto *PN = dyn_cast<PHINode>(II)) {
1407 bool Mapped = false;
1408 // Look for PHI values that we have already mapped (such as the selector).
1409 for (Value *Val : PN->incoming_values()) {
1410 if (VMap.count(Val)) {
1411 VMap[PN] = VMap[Val];
1415 // If we didn't find a match for this value, map it as an undef.
1417 VMap[PN] = UndefValue::get(PN->getType());
1422 // The landing pad value may be used by PHI nodes. It will ultimately be
1423 // eliminated, but we need it in the map for intermediate handling.
1424 VMap[LPad] = UndefValue::get(LPad->getType());
1426 // Skip over PHIs and, if applicable, landingpad instructions.
1427 II = StartBB->getFirstInsertionPt();
1429 CloneAndPruneIntoFromInst(Handler, SrcFn, II, VMap,
1430 /*ModuleLevelChanges=*/false, Returns, "",
1431 &OutlinedFunctionInfo, Director.get());
1433 // Move all the instructions in the cloned "entry" block into our entry block.
1434 // Depending on how the parent function was laid out, the block that will
1435 // correspond to the outlined entry block may not be the first block in the
1436 // list. We can recognize it, however, as the cloned block which has no
1437 // predecessors. Any other block wouldn't have been cloned if it didn't
1438 // have a predecessor which was also cloned.
1439 Function::iterator ClonedIt = std::next(Function::iterator(Entry));
1440 while (!pred_empty(ClonedIt))
1442 BasicBlock *ClonedEntryBB = ClonedIt;
1443 assert(ClonedEntryBB);
1444 Entry->getInstList().splice(Entry->end(), ClonedEntryBB->getInstList());
1445 ClonedEntryBB->eraseFromParent();
1447 // Make sure we can identify the handler's personality later.
1448 addStubInvokeToHandlerIfNeeded(Handler, LPad->getPersonalityFn());
1450 if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
1451 WinEHCatchDirector *CatchDirector =
1452 reinterpret_cast<WinEHCatchDirector *>(Director.get());
1453 CatchAction->setExceptionVar(CatchDirector->getExceptionVar());
1454 CatchAction->setReturnTargets(CatchDirector->getReturnTargets());
1456 // Look for blocks that are not part of the landing pad that we just
1457 // outlined but terminate with a call to llvm.eh.endcatch and a
1458 // branch to a block that is in the handler we just outlined.
1459 // These blocks will be part of a nested landing pad that intends to
1460 // return to an address in this handler. This case is best handled
1461 // after both landing pads have been outlined, so for now we'll just
1462 // save the association of the blocks in LPadTargetBlocks. The
1463 // return instructions which are created from these branches will be
1464 // replaced after all landing pads have been outlined.
1465 for (const auto MapEntry : VMap) {
1466 // VMap maps all values and blocks that were just cloned, but dead
1467 // blocks which were pruned will map to nullptr.
1468 if (!isa<BasicBlock>(MapEntry.first) || MapEntry.second == nullptr)
1470 const BasicBlock *MappedBB = cast<BasicBlock>(MapEntry.first);
1471 for (auto *Pred : predecessors(const_cast<BasicBlock *>(MappedBB))) {
1472 auto *Branch = dyn_cast<BranchInst>(Pred->getTerminator());
1473 if (!Branch || !Branch->isUnconditional() || Pred->size() <= 1)
1475 BasicBlock::iterator II = const_cast<BranchInst *>(Branch);
1477 if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_endcatch>())) {
1478 // This would indicate that a nested landing pad wants to return
1479 // to a block that is outlined into two different handlers.
1480 assert(!LPadTargetBlocks.count(MappedBB));
1481 LPadTargetBlocks[MappedBB] = cast<BasicBlock>(MapEntry.second);
1485 } // End if (CatchAction)
1487 Action->setHandlerBlockOrFunc(Handler);
1492 /// This BB must end in a selector dispatch. All we need to do is pass the
1493 /// handler block to llvm.eh.actions and list it as a possible indirectbr
1495 void WinEHPrepare::processSEHCatchHandler(CatchHandler *CatchAction,
1496 BasicBlock *StartBB) {
1497 BasicBlock *HandlerBB;
1500 bool Res = isSelectorDispatch(StartBB, HandlerBB, Selector, NextBB);
1502 // If this was EH dispatch, this must be a conditional branch to the handler
1504 // FIXME: Handle instructions in the dispatch block. Currently we drop them,
1505 // leading to crashes if some optimization hoists stuff here.
1506 assert(CatchAction->getSelector() && HandlerBB &&
1507 "expected catch EH dispatch");
1509 // This must be a catch-all. Split the block after the landingpad.
1510 assert(CatchAction->getSelector()->isNullValue() && "expected catch-all");
1511 HandlerBB = SplitBlock(StartBB, StartBB->getFirstInsertionPt(), DT);
1513 IRBuilder<> Builder(HandlerBB->getFirstInsertionPt());
1514 Function *EHCodeFn = Intrinsic::getDeclaration(
1515 StartBB->getParent()->getParent(), Intrinsic::eh_exceptioncode);
1516 Value *Code = Builder.CreateCall(EHCodeFn, {}, "sehcode");
1517 Code = Builder.CreateIntToPtr(Code, SEHExceptionCodeSlot->getAllocatedType());
1518 Builder.CreateStore(Code, SEHExceptionCodeSlot);
1519 CatchAction->setHandlerBlockOrFunc(BlockAddress::get(HandlerBB));
1520 TinyPtrVector<BasicBlock *> Targets(HandlerBB);
1521 CatchAction->setReturnTargets(Targets);
1524 void LandingPadMap::mapLandingPad(const LandingPadInst *LPad) {
1525 // Each instance of this class should only ever be used to map a single
1527 assert(OriginLPad == nullptr || OriginLPad == LPad);
1529 // If the landing pad has already been mapped, there's nothing more to do.
1530 if (OriginLPad == LPad)
1535 // The landingpad instruction returns an aggregate value. Typically, its
1536 // value will be passed to a pair of extract value instructions and the
1537 // results of those extracts will have been promoted to reg values before
1538 // this routine is called.
1539 for (auto *U : LPad->users()) {
1540 const ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
1543 assert(Extract->getNumIndices() == 1 &&
1544 "Unexpected operation: extracting both landing pad values");
1545 unsigned int Idx = *(Extract->idx_begin());
1546 assert((Idx == 0 || Idx == 1) &&
1547 "Unexpected operation: extracting an unknown landing pad element");
1549 ExtractedEHPtrs.push_back(Extract);
1550 } else if (Idx == 1) {
1551 ExtractedSelectors.push_back(Extract);
1556 bool LandingPadMap::isOriginLandingPadBlock(const BasicBlock *BB) const {
1557 return BB->getLandingPadInst() == OriginLPad;
1560 bool LandingPadMap::isLandingPadSpecificInst(const Instruction *Inst) const {
1561 if (Inst == OriginLPad)
1563 for (auto *Extract : ExtractedEHPtrs) {
1564 if (Inst == Extract)
1567 for (auto *Extract : ExtractedSelectors) {
1568 if (Inst == Extract)
1574 void LandingPadMap::remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
1575 Value *SelectorValue) const {
1576 // Remap all landing pad extract instructions to the specified values.
1577 for (auto *Extract : ExtractedEHPtrs)
1578 VMap[Extract] = EHPtrValue;
1579 for (auto *Extract : ExtractedSelectors)
1580 VMap[Extract] = SelectorValue;
1583 static bool isFrameAddressCall(const Value *V) {
1584 return match(const_cast<Value *>(V),
1585 m_Intrinsic<Intrinsic::frameaddress>(m_SpecificInt(0)));
1588 CloningDirector::CloningAction WinEHCloningDirectorBase::handleInstruction(
1589 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1590 // If this is one of the boilerplate landing pad instructions, skip it.
1591 // The instruction will have already been remapped in VMap.
1592 if (LPadMap.isLandingPadSpecificInst(Inst))
1593 return CloningDirector::SkipInstruction;
1595 // Nested landing pads that have not already been outlined will be cloned as
1596 // stubs, with just the landingpad instruction and an unreachable instruction.
1597 // When all landingpads have been outlined, we'll replace this with the
1598 // llvm.eh.actions call and indirect branch created when the landing pad was
1600 if (auto *LPad = dyn_cast<LandingPadInst>(Inst)) {
1601 return handleLandingPad(VMap, LPad, NewBB);
1604 // Nested landing pads that have already been outlined will be cloned in their
1605 // outlined form, but we need to intercept the ibr instruction to filter out
1606 // targets that do not return to the handler we are outlining.
1607 if (auto *IBr = dyn_cast<IndirectBrInst>(Inst)) {
1608 return handleIndirectBr(VMap, IBr, NewBB);
1611 if (auto *Invoke = dyn_cast<InvokeInst>(Inst))
1612 return handleInvoke(VMap, Invoke, NewBB);
1614 if (auto *Resume = dyn_cast<ResumeInst>(Inst))
1615 return handleResume(VMap, Resume, NewBB);
1617 if (auto *Cmp = dyn_cast<CmpInst>(Inst))
1618 return handleCompare(VMap, Cmp, NewBB);
1620 if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>()))
1621 return handleBeginCatch(VMap, Inst, NewBB);
1622 if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
1623 return handleEndCatch(VMap, Inst, NewBB);
1624 if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
1625 return handleTypeIdFor(VMap, Inst, NewBB);
1627 // When outlining llvm.frameaddress(i32 0), remap that to the second argument,
1628 // which is the FP of the parent.
1629 if (isFrameAddressCall(Inst)) {
1630 VMap[Inst] = ParentFP;
1631 return CloningDirector::SkipInstruction;
1634 // Continue with the default cloning behavior.
1635 return CloningDirector::CloneInstruction;
1638 CloningDirector::CloningAction WinEHCatchDirector::handleLandingPad(
1639 ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
1640 // If the instruction after the landing pad is a call to llvm.eh.actions
1641 // the landing pad has already been outlined. In this case, we should
1642 // clone it because it may return to a block in the handler we are
1643 // outlining now that would otherwise be unreachable. The landing pads
1644 // are sorted before outlining begins to enable this case to work
1646 const Instruction *NextI = LPad->getNextNode();
1647 if (match(NextI, m_Intrinsic<Intrinsic::eh_actions>()))
1648 return CloningDirector::CloneInstruction;
1650 // If the landing pad hasn't been outlined yet, the landing pad we are
1651 // outlining now does not dominate it and so it cannot return to a block
1652 // in this handler. In that case, we can just insert a stub landing
1653 // pad now and patch it up later.
1654 Instruction *NewInst = LPad->clone();
1655 if (LPad->hasName())
1656 NewInst->setName(LPad->getName());
1657 // Save this correlation for later processing.
1658 NestedLPtoOriginalLP[cast<LandingPadInst>(NewInst)] = LPad;
1659 VMap[LPad] = NewInst;
1660 BasicBlock::InstListType &InstList = NewBB->getInstList();
1661 InstList.push_back(NewInst);
1662 InstList.push_back(new UnreachableInst(NewBB->getContext()));
1663 return CloningDirector::StopCloningBB;
1666 CloningDirector::CloningAction WinEHCatchDirector::handleBeginCatch(
1667 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1668 // The argument to the call is some form of the first element of the
1669 // landingpad aggregate value, but that doesn't matter. It isn't used
1671 // The second argument is an outparameter where the exception object will be
1672 // stored. Typically the exception object is a scalar, but it can be an
1673 // aggregate when catching by value.
1674 // FIXME: Leave something behind to indicate where the exception object lives
1675 // for this handler. Should it be part of llvm.eh.actions?
1676 assert(ExceptionObjectVar == nullptr && "Multiple calls to "
1677 "llvm.eh.begincatch found while "
1678 "outlining catch handler.");
1679 ExceptionObjectVar = Inst->getOperand(1)->stripPointerCasts();
1680 if (isa<ConstantPointerNull>(ExceptionObjectVar))
1681 return CloningDirector::SkipInstruction;
1682 assert(cast<AllocaInst>(ExceptionObjectVar)->isStaticAlloca() &&
1683 "catch parameter is not static alloca");
1684 Materializer.escapeCatchObject(ExceptionObjectVar);
1685 return CloningDirector::SkipInstruction;
1688 CloningDirector::CloningAction
1689 WinEHCatchDirector::handleEndCatch(ValueToValueMapTy &VMap,
1690 const Instruction *Inst, BasicBlock *NewBB) {
1691 auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst);
1692 // It might be interesting to track whether or not we are inside a catch
1693 // function, but that might make the algorithm more brittle than it needs
1696 // The end catch call can occur in one of two places: either in a
1697 // landingpad block that is part of the catch handlers exception mechanism,
1698 // or at the end of the catch block. However, a catch-all handler may call
1699 // end catch from the original landing pad. If the call occurs in a nested
1700 // landing pad block, we must skip it and continue so that the landing pad
1702 auto *ParentBB = IntrinCall->getParent();
1703 if (ParentBB->isLandingPad() && !LPadMap.isOriginLandingPadBlock(ParentBB))
1704 return CloningDirector::SkipInstruction;
1706 // If an end catch occurs anywhere else we want to terminate the handler
1707 // with a return to the code that follows the endcatch call. If the
1708 // next instruction is not an unconditional branch, we need to split the
1709 // block to provide a clear target for the return instruction.
1710 BasicBlock *ContinueBB;
1711 auto Next = std::next(BasicBlock::const_iterator(IntrinCall));
1712 const BranchInst *Branch = dyn_cast<BranchInst>(Next);
1713 if (!Branch || !Branch->isUnconditional()) {
1714 // We're interrupting the cloning process at this location, so the
1715 // const_cast we're doing here will not cause a problem.
1716 ContinueBB = SplitBlock(const_cast<BasicBlock *>(ParentBB),
1717 const_cast<Instruction *>(cast<Instruction>(Next)));
1719 ContinueBB = Branch->getSuccessor(0);
1722 ReturnInst::Create(NewBB->getContext(), BlockAddress::get(ContinueBB), NewBB);
1723 ReturnTargets.push_back(ContinueBB);
1725 // We just added a terminator to the cloned block.
1726 // Tell the caller to stop processing the current basic block so that
1727 // the branch instruction will be skipped.
1728 return CloningDirector::StopCloningBB;
1731 CloningDirector::CloningAction WinEHCatchDirector::handleTypeIdFor(
1732 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1733 auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst);
1734 Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts();
1735 // This causes a replacement that will collapse the landing pad CFG based
1736 // on the filter function we intend to match.
1737 if (Selector == CurrentSelector)
1738 VMap[Inst] = ConstantInt::get(SelectorIDType, 1);
1740 VMap[Inst] = ConstantInt::get(SelectorIDType, 0);
1741 // Tell the caller not to clone this instruction.
1742 return CloningDirector::SkipInstruction;
1745 CloningDirector::CloningAction WinEHCatchDirector::handleIndirectBr(
1746 ValueToValueMapTy &VMap,
1747 const IndirectBrInst *IBr,
1748 BasicBlock *NewBB) {
1749 // If this indirect branch is not part of a landing pad block, just clone it.
1750 const BasicBlock *ParentBB = IBr->getParent();
1751 if (!ParentBB->isLandingPad())
1752 return CloningDirector::CloneInstruction;
1754 // If it is part of a landing pad, we want to filter out target blocks
1755 // that are not part of the handler we are outlining.
1756 const LandingPadInst *LPad = ParentBB->getLandingPadInst();
1758 // Save this correlation for later processing.
1759 NestedLPtoOriginalLP[cast<LandingPadInst>(VMap[LPad])] = LPad;
1761 // We should only get here for landing pads that have already been outlined.
1762 assert(match(LPad->getNextNode(), m_Intrinsic<Intrinsic::eh_actions>()));
1764 // Copy the indirectbr, but only include targets that were previously
1765 // identified as EH blocks and are dominated by the nested landing pad.
1766 SetVector<const BasicBlock *> ReturnTargets;
1767 for (int I = 0, E = IBr->getNumDestinations(); I < E; ++I) {
1768 auto *TargetBB = IBr->getDestination(I);
1769 if (EHBlocks.count(const_cast<BasicBlock*>(TargetBB)) &&
1770 DT->dominates(ParentBB, TargetBB)) {
1771 DEBUG(dbgs() << " Adding destination " << TargetBB->getName() << "\n");
1772 ReturnTargets.insert(TargetBB);
1775 IndirectBrInst *NewBranch =
1776 IndirectBrInst::Create(const_cast<Value *>(IBr->getAddress()),
1777 ReturnTargets.size(), NewBB);
1778 for (auto *Target : ReturnTargets)
1779 NewBranch->addDestination(const_cast<BasicBlock*>(Target));
1781 // The operands and targets of the branch instruction are remapped later
1782 // because it is a terminator. Tell the cloning code to clone the
1783 // blocks we just added to the target list.
1784 return CloningDirector::CloneSuccessors;
1787 CloningDirector::CloningAction
1788 WinEHCatchDirector::handleInvoke(ValueToValueMapTy &VMap,
1789 const InvokeInst *Invoke, BasicBlock *NewBB) {
1790 return CloningDirector::CloneInstruction;
1793 CloningDirector::CloningAction
1794 WinEHCatchDirector::handleResume(ValueToValueMapTy &VMap,
1795 const ResumeInst *Resume, BasicBlock *NewBB) {
1796 // Resume instructions shouldn't be reachable from catch handlers.
1797 // We still need to handle it, but it will be pruned.
1798 BasicBlock::InstListType &InstList = NewBB->getInstList();
1799 InstList.push_back(new UnreachableInst(NewBB->getContext()));
1800 return CloningDirector::StopCloningBB;
1803 CloningDirector::CloningAction
1804 WinEHCatchDirector::handleCompare(ValueToValueMapTy &VMap,
1805 const CmpInst *Compare, BasicBlock *NewBB) {
1806 const IntrinsicInst *IntrinCall = nullptr;
1807 if (match(Compare->getOperand(0), m_Intrinsic<Intrinsic::eh_typeid_for>())) {
1808 IntrinCall = dyn_cast<IntrinsicInst>(Compare->getOperand(0));
1809 } else if (match(Compare->getOperand(1),
1810 m_Intrinsic<Intrinsic::eh_typeid_for>())) {
1811 IntrinCall = dyn_cast<IntrinsicInst>(Compare->getOperand(1));
1814 Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts();
1815 // This causes a replacement that will collapse the landing pad CFG based
1816 // on the filter function we intend to match.
1817 if (Selector == CurrentSelector->stripPointerCasts()) {
1818 VMap[Compare] = ConstantInt::get(SelectorIDType, 1);
1820 VMap[Compare] = ConstantInt::get(SelectorIDType, 0);
1822 return CloningDirector::SkipInstruction;
1824 return CloningDirector::CloneInstruction;
1827 CloningDirector::CloningAction WinEHCleanupDirector::handleLandingPad(
1828 ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
1829 // The MS runtime will terminate the process if an exception occurs in a
1830 // cleanup handler, so we shouldn't encounter landing pads in the actual
1831 // cleanup code, but they may appear in catch blocks. Depending on where
1832 // we started cloning we may see one, but it will get dropped during dead
1834 Instruction *NewInst = new UnreachableInst(NewBB->getContext());
1835 VMap[LPad] = NewInst;
1836 BasicBlock::InstListType &InstList = NewBB->getInstList();
1837 InstList.push_back(NewInst);
1838 return CloningDirector::StopCloningBB;
1841 CloningDirector::CloningAction WinEHCleanupDirector::handleBeginCatch(
1842 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1843 // Cleanup code may flow into catch blocks or the catch block may be part
1844 // of a branch that will be optimized away. We'll insert a return
1845 // instruction now, but it may be pruned before the cloning process is
1847 ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
1848 return CloningDirector::StopCloningBB;
1851 CloningDirector::CloningAction WinEHCleanupDirector::handleEndCatch(
1852 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1853 // Cleanup handlers nested within catch handlers may begin with a call to
1854 // eh.endcatch. We can just ignore that instruction.
1855 return CloningDirector::SkipInstruction;
1858 CloningDirector::CloningAction WinEHCleanupDirector::handleTypeIdFor(
1859 ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
1860 // If we encounter a selector comparison while cloning a cleanup handler,
1861 // we want to stop cloning immediately. Anything after the dispatch
1862 // will be outlined into a different handler.
1863 BasicBlock *CatchHandler;
1866 if (isSelectorDispatch(const_cast<BasicBlock *>(Inst->getParent()),
1867 CatchHandler, Selector, NextBB)) {
1868 ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
1869 return CloningDirector::StopCloningBB;
1871 // If eg.typeid.for is called for any other reason, it can be ignored.
1872 VMap[Inst] = ConstantInt::get(SelectorIDType, 0);
1873 return CloningDirector::SkipInstruction;
1876 CloningDirector::CloningAction WinEHCleanupDirector::handleIndirectBr(
1877 ValueToValueMapTy &VMap,
1878 const IndirectBrInst *IBr,
1879 BasicBlock *NewBB) {
1880 // No special handling is required for cleanup cloning.
1881 return CloningDirector::CloneInstruction;
1884 CloningDirector::CloningAction WinEHCleanupDirector::handleInvoke(
1885 ValueToValueMapTy &VMap, const InvokeInst *Invoke, BasicBlock *NewBB) {
1886 // All invokes in cleanup handlers can be replaced with calls.
1887 SmallVector<Value *, 16> CallArgs(Invoke->op_begin(), Invoke->op_end() - 3);
1888 // Insert a normal call instruction...
1890 CallInst::Create(const_cast<Value *>(Invoke->getCalledValue()), CallArgs,
1891 Invoke->getName(), NewBB);
1892 NewCall->setCallingConv(Invoke->getCallingConv());
1893 NewCall->setAttributes(Invoke->getAttributes());
1894 NewCall->setDebugLoc(Invoke->getDebugLoc());
1895 VMap[Invoke] = NewCall;
1897 // Remap the operands.
1898 llvm::RemapInstruction(NewCall, VMap, RF_None, nullptr, &Materializer);
1900 // Insert an unconditional branch to the normal destination.
1901 BranchInst::Create(Invoke->getNormalDest(), NewBB);
1903 // The unwind destination won't be cloned into the new function, so
1904 // we don't need to clean up its phi nodes.
1906 // We just added a terminator to the cloned block.
1907 // Tell the caller to stop processing the current basic block.
1908 return CloningDirector::CloneSuccessors;
1911 CloningDirector::CloningAction WinEHCleanupDirector::handleResume(
1912 ValueToValueMapTy &VMap, const ResumeInst *Resume, BasicBlock *NewBB) {
1913 ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
1915 // We just added a terminator to the cloned block.
1916 // Tell the caller to stop processing the current basic block so that
1917 // the branch instruction will be skipped.
1918 return CloningDirector::StopCloningBB;
1921 CloningDirector::CloningAction
1922 WinEHCleanupDirector::handleCompare(ValueToValueMapTy &VMap,
1923 const CmpInst *Compare, BasicBlock *NewBB) {
1924 if (match(Compare->getOperand(0), m_Intrinsic<Intrinsic::eh_typeid_for>()) ||
1925 match(Compare->getOperand(1), m_Intrinsic<Intrinsic::eh_typeid_for>())) {
1926 VMap[Compare] = ConstantInt::get(SelectorIDType, 1);
1927 return CloningDirector::SkipInstruction;
1929 return CloningDirector::CloneInstruction;
1932 WinEHFrameVariableMaterializer::WinEHFrameVariableMaterializer(
1933 Function *OutlinedFn, Value *ParentFP, FrameVarInfoMap &FrameVarInfo)
1934 : FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) {
1935 BasicBlock *EntryBB = &OutlinedFn->getEntryBlock();
1937 // New allocas should be inserted in the entry block, but after the parent FP
1938 // is established if it is an instruction.
1939 Instruction *InsertPoint = EntryBB->getFirstInsertionPt();
1940 if (auto *FPInst = dyn_cast<Instruction>(ParentFP))
1941 InsertPoint = FPInst->getNextNode();
1942 Builder.SetInsertPoint(EntryBB, InsertPoint);
1945 Value *WinEHFrameVariableMaterializer::materializeValueFor(Value *V) {
1946 // If we're asked to materialize a static alloca, we temporarily create an
1947 // alloca in the outlined function and add this to the FrameVarInfo map. When
1948 // all the outlining is complete, we'll replace these temporary allocas with
1949 // calls to llvm.framerecover.
1950 if (auto *AV = dyn_cast<AllocaInst>(V)) {
1951 assert(AV->isStaticAlloca() &&
1952 "cannot materialize un-demoted dynamic alloca");
1953 AllocaInst *NewAlloca = dyn_cast<AllocaInst>(AV->clone());
1954 Builder.Insert(NewAlloca, AV->getName());
1955 FrameVarInfo[AV].push_back(NewAlloca);
1959 if (isa<Instruction>(V) || isa<Argument>(V)) {
1960 Function *Parent = isa<Instruction>(V)
1961 ? cast<Instruction>(V)->getParent()->getParent()
1962 : cast<Argument>(V)->getParent();
1964 << "Failed to demote instruction used in exception handler of function "
1965 << GlobalValue::getRealLinkageName(Parent->getName()) << ":\n";
1966 errs() << " " << *V << '\n';
1967 report_fatal_error("WinEHPrepare failed to demote instruction");
1970 // Don't materialize other values.
1974 void WinEHFrameVariableMaterializer::escapeCatchObject(Value *V) {
1975 // Catch parameter objects have to live in the parent frame. When we see a use
1976 // of a catch parameter, add a sentinel to the multimap to indicate that it's
1977 // used from another handler. This will prevent us from trying to sink the
1978 // alloca into the handler and ensure that the catch parameter is present in
1979 // the call to llvm.frameescape.
1980 FrameVarInfo[V].push_back(getCatchObjectSentinel());
1983 // This function maps the catch and cleanup handlers that are reachable from the
1984 // specified landing pad. The landing pad sequence will have this basic shape:
1986 // <cleanup handler>
1987 // <selector comparison>
1989 // <cleanup handler>
1990 // <selector comparison>
1992 // <cleanup handler>
1995 // Any of the cleanup slots may be absent. The cleanup slots may be occupied by
1996 // any arbitrary control flow, but all paths through the cleanup code must
1997 // eventually reach the next selector comparison and no path can skip to a
1998 // different selector comparisons, though some paths may terminate abnormally.
1999 // Therefore, we will use a depth first search from the start of any given
2000 // cleanup block and stop searching when we find the next selector comparison.
2002 // If the landingpad instruction does not have a catch clause, we will assume
2003 // that any instructions other than selector comparisons and catch handlers can
2004 // be ignored. In practice, these will only be the boilerplate instructions.
2006 // The catch handlers may also have any control structure, but we are only
2007 // interested in the start of the catch handlers, so we don't need to actually
2008 // follow the flow of the catch handlers. The start of the catch handlers can
2009 // be located from the compare instructions, but they can be skipped in the
2010 // flow by following the contrary branch.
2011 void WinEHPrepare::mapLandingPadBlocks(LandingPadInst *LPad,
2012 LandingPadActions &Actions) {
2013 unsigned int NumClauses = LPad->getNumClauses();
2014 unsigned int HandlersFound = 0;
2015 BasicBlock *BB = LPad->getParent();
2017 DEBUG(dbgs() << "Mapping landing pad: " << BB->getName() << "\n");
2019 if (NumClauses == 0) {
2020 findCleanupHandlers(Actions, BB, nullptr);
2024 VisitedBlockSet VisitedBlocks;
2026 while (HandlersFound != NumClauses) {
2027 BasicBlock *NextBB = nullptr;
2029 // Skip over filter clauses.
2030 if (LPad->isFilter(HandlersFound)) {
2035 // See if the clause we're looking for is a catch-all.
2036 // If so, the catch begins immediately.
2037 Constant *ExpectedSelector =
2038 LPad->getClause(HandlersFound)->stripPointerCasts();
2039 if (isa<ConstantPointerNull>(ExpectedSelector)) {
2040 // The catch all must occur last.
2041 assert(HandlersFound == NumClauses - 1);
2043 // There can be additional selector dispatches in the call chain that we
2045 BasicBlock *CatchBlock = nullptr;
2047 while (BB && isSelectorDispatch(BB, CatchBlock, Selector, NextBB)) {
2048 DEBUG(dbgs() << " Found extra catch dispatch in block "
2049 << CatchBlock->getName() << "\n");
2053 // Add the catch handler to the action list.
2054 CatchHandler *Action = nullptr;
2055 if (CatchHandlerMap.count(BB) && CatchHandlerMap[BB] != nullptr) {
2056 // If the CatchHandlerMap already has an entry for this BB, re-use it.
2057 Action = CatchHandlerMap[BB];
2058 assert(Action->getSelector() == ExpectedSelector);
2060 // We don't expect a selector dispatch, but there may be a call to
2061 // llvm.eh.begincatch, which separates catch handling code from
2062 // cleanup code in the same control flow. This call looks for the
2063 // begincatch intrinsic.
2064 Action = findCatchHandler(BB, NextBB, VisitedBlocks);
2066 // For C++ EH, check if there is any interesting cleanup code before
2067 // we begin the catch. This is important because cleanups cannot
2068 // rethrow exceptions but code called from catches can. For SEH, it
2069 // isn't important if some finally code before a catch-all is executed
2070 // out of line or after recovering from the exception.
2071 if (Personality == EHPersonality::MSVC_CXX)
2072 findCleanupHandlers(Actions, BB, BB);
2074 // If an action was not found, it means that the control flows
2075 // directly into the catch-all handler and there is no cleanup code.
2076 // That's an expected situation and we must create a catch action.
2077 // Since this is a catch-all handler, the selector won't actually
2078 // appear in the code anywhere. ExpectedSelector here is the constant
2079 // null ptr that we got from the landing pad instruction.
2080 Action = new CatchHandler(BB, ExpectedSelector, nullptr);
2081 CatchHandlerMap[BB] = Action;
2084 Actions.insertCatchHandler(Action);
2085 DEBUG(dbgs() << " Catch all handler at block " << BB->getName() << "\n");
2088 // Once we reach a catch-all, don't expect to hit a resume instruction.
2093 CatchHandler *CatchAction = findCatchHandler(BB, NextBB, VisitedBlocks);
2094 assert(CatchAction);
2096 // See if there is any interesting code executed before the dispatch.
2097 findCleanupHandlers(Actions, BB, CatchAction->getStartBlock());
2099 // When the source program contains multiple nested try blocks the catch
2100 // handlers can get strung together in such a way that we can encounter
2101 // a dispatch for a selector that we've already had a handler for.
2102 if (CatchAction->getSelector()->stripPointerCasts() == ExpectedSelector) {
2105 // Add the catch handler to the action list.
2106 DEBUG(dbgs() << " Found catch dispatch in block "
2107 << CatchAction->getStartBlock()->getName() << "\n");
2108 Actions.insertCatchHandler(CatchAction);
2110 // Under some circumstances optimized IR will flow unconditionally into a
2111 // handler block without checking the selector. This can only happen if
2112 // the landing pad has a catch-all handler and the handler for the
2113 // preceeding catch clause is identical to the catch-call handler
2114 // (typically an empty catch). In this case, the handler must be shared
2115 // by all remaining clauses.
2116 if (isa<ConstantPointerNull>(
2117 CatchAction->getSelector()->stripPointerCasts())) {
2118 DEBUG(dbgs() << " Applying early catch-all handler in block "
2119 << CatchAction->getStartBlock()->getName()
2120 << " to all remaining clauses.\n");
2121 Actions.insertCatchHandler(CatchAction);
2125 DEBUG(dbgs() << " Found extra catch dispatch in block "
2126 << CatchAction->getStartBlock()->getName() << "\n");
2129 // Move on to the block after the catch handler.
2133 // If we didn't wind up in a catch-all, see if there is any interesting code
2134 // executed before the resume.
2135 findCleanupHandlers(Actions, BB, BB);
2137 // It's possible that some optimization moved code into a landingpad that
2139 // previously being used for cleanup. If that happens, we need to execute
2141 // extra code from a cleanup handler.
2142 if (Actions.includesCleanup() && !LPad->isCleanup())
2143 LPad->setCleanup(true);
2146 // This function searches starting with the input block for the next
2147 // block that terminates with a branch whose condition is based on a selector
2148 // comparison. This may be the input block. See the mapLandingPadBlocks
2149 // comments for a discussion of control flow assumptions.
2151 CatchHandler *WinEHPrepare::findCatchHandler(BasicBlock *BB,
2152 BasicBlock *&NextBB,
2153 VisitedBlockSet &VisitedBlocks) {
2154 // See if we've already found a catch handler use it.
2155 // Call count() first to avoid creating a null entry for blocks
2156 // we haven't seen before.
2157 if (CatchHandlerMap.count(BB) && CatchHandlerMap[BB] != nullptr) {
2158 CatchHandler *Action = cast<CatchHandler>(CatchHandlerMap[BB]);
2159 NextBB = Action->getNextBB();
2163 // VisitedBlocks applies only to the current search. We still
2164 // need to consider blocks that we've visited while mapping other
2166 VisitedBlocks.insert(BB);
2168 BasicBlock *CatchBlock = nullptr;
2169 Constant *Selector = nullptr;
2171 // If this is the first time we've visited this block from any landing pad
2172 // look to see if it is a selector dispatch block.
2173 if (!CatchHandlerMap.count(BB)) {
2174 if (isSelectorDispatch(BB, CatchBlock, Selector, NextBB)) {
2175 CatchHandler *Action = new CatchHandler(BB, Selector, NextBB);
2176 CatchHandlerMap[BB] = Action;
2179 // If we encounter a block containing an llvm.eh.begincatch before we
2180 // find a selector dispatch block, the handler is assumed to be
2181 // reached unconditionally. This happens for catch-all blocks, but
2182 // it can also happen for other catch handlers that have been combined
2183 // with the catch-all handler during optimization.
2184 if (isCatchBlock(BB)) {
2185 PointerType *Int8PtrTy = Type::getInt8PtrTy(BB->getContext());
2186 Constant *NullSelector = ConstantPointerNull::get(Int8PtrTy);
2187 CatchHandler *Action = new CatchHandler(BB, NullSelector, nullptr);
2188 CatchHandlerMap[BB] = Action;
2193 // Visit each successor, looking for the dispatch.
2194 // FIXME: We expect to find the dispatch quickly, so this will probably
2195 // work better as a breadth first search.
2196 for (BasicBlock *Succ : successors(BB)) {
2197 if (VisitedBlocks.count(Succ))
2200 CatchHandler *Action = findCatchHandler(Succ, NextBB, VisitedBlocks);
2207 // These are helper functions to combine repeated code from findCleanupHandlers.
2208 static void createCleanupHandler(LandingPadActions &Actions,
2209 CleanupHandlerMapTy &CleanupHandlerMap,
2211 CleanupHandler *Action = new CleanupHandler(BB);
2212 CleanupHandlerMap[BB] = Action;
2213 Actions.insertCleanupHandler(Action);
2214 DEBUG(dbgs() << " Found cleanup code in block "
2215 << Action->getStartBlock()->getName() << "\n");
2218 static CallSite matchOutlinedFinallyCall(BasicBlock *BB,
2219 Instruction *MaybeCall) {
2220 // Look for finally blocks that Clang has already outlined for us.
2221 // %fp = call i8* @llvm.frameaddress(i32 0)
2222 // call void @"fin$parent"(iN 1, i8* %fp)
2223 if (isFrameAddressCall(MaybeCall) && MaybeCall != BB->getTerminator())
2224 MaybeCall = MaybeCall->getNextNode();
2225 CallSite FinallyCall(MaybeCall);
2226 if (!FinallyCall || FinallyCall.arg_size() != 2)
2228 if (!match(FinallyCall.getArgument(0), m_SpecificInt(1)))
2230 if (!isFrameAddressCall(FinallyCall.getArgument(1)))
2235 static BasicBlock *followSingleUnconditionalBranches(BasicBlock *BB) {
2236 // Skip single ubr blocks.
2237 while (BB->getFirstNonPHIOrDbg() == BB->getTerminator()) {
2238 auto *Br = dyn_cast<BranchInst>(BB->getTerminator());
2239 if (Br && Br->isUnconditional())
2240 BB = Br->getSuccessor(0);
2247 // This function searches starting with the input block for the next block that
2248 // contains code that is not part of a catch handler and would not be eliminated
2249 // during handler outlining.
2251 void WinEHPrepare::findCleanupHandlers(LandingPadActions &Actions,
2252 BasicBlock *StartBB, BasicBlock *EndBB) {
2253 // Here we will skip over the following:
2255 // landing pad prolog:
2257 // Unconditional branches
2259 // Selector dispatch
2263 // Anything else marks the start of an interesting block
2265 BasicBlock *BB = StartBB;
2266 // Anything other than an unconditional branch will kick us out of this loop
2267 // one way or another.
2269 BB = followSingleUnconditionalBranches(BB);
2270 // If we've already scanned this block, don't scan it again. If it is
2271 // a cleanup block, there will be an action in the CleanupHandlerMap.
2272 // If we've scanned it and it is not a cleanup block, there will be a
2273 // nullptr in the CleanupHandlerMap. If we have not scanned it, there will
2274 // be no entry in the CleanupHandlerMap. We must call count() first to
2275 // avoid creating a null entry for blocks we haven't scanned.
2276 if (CleanupHandlerMap.count(BB)) {
2277 if (auto *Action = CleanupHandlerMap[BB]) {
2278 Actions.insertCleanupHandler(Action);
2279 DEBUG(dbgs() << " Found cleanup code in block "
2280 << Action->getStartBlock()->getName() << "\n");
2281 // FIXME: This cleanup might chain into another, and we need to discover
2285 // Here we handle the case where the cleanup handler map contains a
2286 // value for this block but the value is a nullptr. This means that
2287 // we have previously analyzed the block and determined that it did
2288 // not contain any cleanup code. Based on the earlier analysis, we
2289 // know the the block must end in either an unconditional branch, a
2290 // resume or a conditional branch that is predicated on a comparison
2291 // with a selector. Either the resume or the selector dispatch
2292 // would terminate the search for cleanup code, so the unconditional
2293 // branch is the only case for which we might need to continue
2295 BasicBlock *SuccBB = followSingleUnconditionalBranches(BB);
2296 if (SuccBB == BB || SuccBB == EndBB)
2303 // Create an entry in the cleanup handler map for this block. Initially
2304 // we create an entry that says this isn't a cleanup block. If we find
2305 // cleanup code, the caller will replace this entry.
2306 CleanupHandlerMap[BB] = nullptr;
2308 TerminatorInst *Terminator = BB->getTerminator();
2310 // Landing pad blocks have extra instructions we need to accept.
2311 LandingPadMap *LPadMap = nullptr;
2312 if (BB->isLandingPad()) {
2313 LandingPadInst *LPad = BB->getLandingPadInst();
2314 LPadMap = &LPadMaps[LPad];
2315 if (!LPadMap->isInitialized())
2316 LPadMap->mapLandingPad(LPad);
2319 // Look for the bare resume pattern:
2320 // %lpad.val1 = insertvalue { i8*, i32 } undef, i8* %exn, 0
2321 // %lpad.val2 = insertvalue { i8*, i32 } %lpad.val1, i32 %sel, 1
2322 // resume { i8*, i32 } %lpad.val2
2323 if (auto *Resume = dyn_cast<ResumeInst>(Terminator)) {
2324 InsertValueInst *Insert1 = nullptr;
2325 InsertValueInst *Insert2 = nullptr;
2326 Value *ResumeVal = Resume->getOperand(0);
2327 // If the resume value isn't a phi or landingpad value, it should be a
2328 // series of insertions. Identify them so we can avoid them when scanning
2330 if (!isa<PHINode>(ResumeVal) && !isa<LandingPadInst>(ResumeVal)) {
2331 Insert2 = dyn_cast<InsertValueInst>(ResumeVal);
2333 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2334 Insert1 = dyn_cast<InsertValueInst>(Insert2->getAggregateOperand());
2336 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2338 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
2340 Instruction *Inst = II;
2341 if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
2343 if (Inst == Insert1 || Inst == Insert2 || Inst == Resume)
2345 if (!Inst->hasOneUse() ||
2346 (Inst->user_back() != Insert1 && Inst->user_back() != Insert2)) {
2347 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2353 BranchInst *Branch = dyn_cast<BranchInst>(Terminator);
2354 if (Branch && Branch->isConditional()) {
2355 // Look for the selector dispatch.
2356 // %2 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIf to i8*))
2357 // %matches = icmp eq i32 %sel, %2
2358 // br i1 %matches, label %catch14, label %eh.resume
2359 CmpInst *Compare = dyn_cast<CmpInst>(Branch->getCondition());
2360 if (!Compare || !Compare->isEquality())
2361 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2362 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
2364 Instruction *Inst = II;
2365 if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
2367 if (Inst == Compare || Inst == Branch)
2369 if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
2371 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2373 // The selector dispatch block should always terminate our search.
2374 assert(BB == EndBB);
2378 if (isAsynchronousEHPersonality(Personality)) {
2379 // If this is a landingpad block, split the block at the first non-landing
2381 Instruction *MaybeCall = BB->getFirstNonPHIOrDbg();
2383 while (MaybeCall != BB->getTerminator() &&
2384 LPadMap->isLandingPadSpecificInst(MaybeCall))
2385 MaybeCall = MaybeCall->getNextNode();
2388 // Look for outlined finally calls.
2389 if (CallSite FinallyCall = matchOutlinedFinallyCall(BB, MaybeCall)) {
2390 Function *Fin = FinallyCall.getCalledFunction();
2391 assert(Fin && "outlined finally call should be direct");
2392 auto *Action = new CleanupHandler(BB);
2393 Action->setHandlerBlockOrFunc(Fin);
2394 Actions.insertCleanupHandler(Action);
2395 CleanupHandlerMap[BB] = Action;
2396 DEBUG(dbgs() << " Found frontend-outlined finally call to "
2397 << Fin->getName() << " in block "
2398 << Action->getStartBlock()->getName() << "\n");
2400 // Split the block if there were more interesting instructions and look
2401 // for finally calls in the normal successor block.
2402 BasicBlock *SuccBB = BB;
2403 if (FinallyCall.getInstruction() != BB->getTerminator() &&
2404 FinallyCall.getInstruction()->getNextNode() !=
2405 BB->getTerminator()) {
2407 SplitBlock(BB, FinallyCall.getInstruction()->getNextNode(), DT);
2409 if (FinallyCall.isInvoke()) {
2411 cast<InvokeInst>(FinallyCall.getInstruction())->getNormalDest();
2413 SuccBB = BB->getUniqueSuccessor();
2415 "splitOutlinedFinallyCalls didn't insert a branch");
2425 // Anything else is either a catch block or interesting cleanup code.
2426 for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
2428 Instruction *Inst = II;
2429 if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
2431 // Unconditional branches fall through to this loop.
2434 // If this is a catch block, there is no cleanup code to be found.
2435 if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>()))
2437 // If this a nested landing pad, it may contain an endcatch call.
2438 if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
2440 // Anything else makes this interesting cleanup code.
2441 return createCleanupHandler(Actions, CleanupHandlerMap, BB);
2444 // Only unconditional branches in empty blocks should get this far.
2445 assert(Branch && Branch->isUnconditional());
2448 BB = Branch->getSuccessor(0);
2452 // This is a public function, declared in WinEHFuncInfo.h and is also
2453 // referenced by WinEHNumbering in FunctionLoweringInfo.cpp.
2454 void llvm::parseEHActions(
2455 const IntrinsicInst *II,
2456 SmallVectorImpl<std::unique_ptr<ActionHandler>> &Actions) {
2457 for (unsigned I = 0, E = II->getNumArgOperands(); I != E;) {
2458 uint64_t ActionKind =
2459 cast<ConstantInt>(II->getArgOperand(I))->getZExtValue();
2460 if (ActionKind == /*catch=*/1) {
2461 auto *Selector = cast<Constant>(II->getArgOperand(I + 1));
2462 ConstantInt *EHObjIndex = cast<ConstantInt>(II->getArgOperand(I + 2));
2463 int64_t EHObjIndexVal = EHObjIndex->getSExtValue();
2464 Constant *Handler = cast<Constant>(II->getArgOperand(I + 3));
2466 auto CH = make_unique<CatchHandler>(/*BB=*/nullptr, Selector,
2467 /*NextBB=*/nullptr);
2468 CH->setHandlerBlockOrFunc(Handler);
2469 CH->setExceptionVarIndex(EHObjIndexVal);
2470 Actions.push_back(std::move(CH));
2471 } else if (ActionKind == 0) {
2472 Constant *Handler = cast<Constant>(II->getArgOperand(I + 1));
2474 auto CH = make_unique<CleanupHandler>(/*BB=*/nullptr);
2475 CH->setHandlerBlockOrFunc(Handler);
2476 Actions.push_back(std::move(CH));
2478 llvm_unreachable("Expected either a catch or cleanup handler!");
2481 std::reverse(Actions.begin(), Actions.end());
2485 struct WinEHNumbering {
2486 WinEHNumbering(WinEHFuncInfo &FuncInfo) : FuncInfo(FuncInfo),
2487 CurrentBaseState(-1), NextState(0) {}
2489 WinEHFuncInfo &FuncInfo;
2490 int CurrentBaseState;
2493 SmallVector<std::unique_ptr<ActionHandler>, 4> HandlerStack;
2494 SmallPtrSet<const Function *, 4> VisitedHandlers;
2496 int currentEHNumber() const {
2497 return HandlerStack.empty() ? CurrentBaseState : HandlerStack.back()->getEHState();
2500 void createUnwindMapEntry(int ToState, ActionHandler *AH);
2501 void createTryBlockMapEntry(int TryLow, int TryHigh,
2502 ArrayRef<CatchHandler *> Handlers);
2503 void processCallSite(MutableArrayRef<std::unique_ptr<ActionHandler>> Actions,
2504 ImmutableCallSite CS);
2505 void popUnmatchedActions(int FirstMismatch);
2506 void calculateStateNumbers(const Function &F);
2507 void findActionRootLPads(const Function &F);
2511 void WinEHNumbering::createUnwindMapEntry(int ToState, ActionHandler *AH) {
2512 WinEHUnwindMapEntry UME;
2513 UME.ToState = ToState;
2514 if (auto *CH = dyn_cast_or_null<CleanupHandler>(AH))
2515 UME.Cleanup = cast<Function>(CH->getHandlerBlockOrFunc());
2517 UME.Cleanup = nullptr;
2518 FuncInfo.UnwindMap.push_back(UME);
2521 void WinEHNumbering::createTryBlockMapEntry(int TryLow, int TryHigh,
2522 ArrayRef<CatchHandler *> Handlers) {
2523 // See if we already have an entry for this set of handlers.
2524 // This is using iterators rather than a range-based for loop because
2525 // if we find the entry we're looking for we'll need the iterator to erase it.
2526 int NumHandlers = Handlers.size();
2527 auto I = FuncInfo.TryBlockMap.begin();
2528 auto E = FuncInfo.TryBlockMap.end();
2529 for ( ; I != E; ++I) {
2531 if (Entry.HandlerArray.size() != (size_t)NumHandlers)
2534 for (N = 0; N < NumHandlers; ++N) {
2535 if (Entry.HandlerArray[N].Handler != Handlers[N]->getHandlerBlockOrFunc())
2536 break; // breaks out of inner loop
2538 // If all the handlers match, this is what we were looking for.
2539 if (N == NumHandlers) {
2544 // If we found an existing entry for this set of handlers, extend the range
2545 // but move the entry to the end of the map vector. The order of entries
2546 // in the map is critical to the way that the runtime finds handlers.
2547 // FIXME: Depending on what has happened with block ordering, this may
2548 // incorrectly combine entries that should remain separate.
2550 // Copy the existing entry.
2551 WinEHTryBlockMapEntry Entry = *I;
2552 Entry.TryLow = std::min(TryLow, Entry.TryLow);
2553 Entry.TryHigh = std::max(TryHigh, Entry.TryHigh);
2554 assert(Entry.TryLow <= Entry.TryHigh);
2555 // Erase the old entry and add this one to the back.
2556 FuncInfo.TryBlockMap.erase(I);
2557 FuncInfo.TryBlockMap.push_back(Entry);
2561 // If we didn't find an entry, create a new one.
2562 WinEHTryBlockMapEntry TBME;
2563 TBME.TryLow = TryLow;
2564 TBME.TryHigh = TryHigh;
2565 assert(TBME.TryLow <= TBME.TryHigh);
2566 for (CatchHandler *CH : Handlers) {
2567 WinEHHandlerType HT;
2568 if (CH->getSelector()->isNullValue()) {
2569 HT.Adjectives = 0x40;
2570 HT.TypeDescriptor = nullptr;
2572 auto *GV = cast<GlobalVariable>(CH->getSelector()->stripPointerCasts());
2573 // Selectors are always pointers to GlobalVariables with 'struct' type.
2574 // The struct has two fields, adjectives and a type descriptor.
2575 auto *CS = cast<ConstantStruct>(GV->getInitializer());
2577 cast<ConstantInt>(CS->getAggregateElement(0U))->getZExtValue();
2579 cast<GlobalVariable>(CS->getAggregateElement(1)->stripPointerCasts());
2581 HT.Handler = cast<Function>(CH->getHandlerBlockOrFunc());
2582 HT.CatchObjRecoverIdx = CH->getExceptionVarIndex();
2583 TBME.HandlerArray.push_back(HT);
2585 FuncInfo.TryBlockMap.push_back(TBME);
2588 static void print_name(const Value *V) {
2591 DEBUG(dbgs() << "null");
2595 if (const auto *F = dyn_cast<Function>(V))
2596 DEBUG(dbgs() << F->getName());
2602 void WinEHNumbering::processCallSite(
2603 MutableArrayRef<std::unique_ptr<ActionHandler>> Actions,
2604 ImmutableCallSite CS) {
2605 DEBUG(dbgs() << "processCallSite (EH state = " << currentEHNumber()
2607 print_name(CS ? CS.getCalledValue() : nullptr);
2608 DEBUG(dbgs() << '\n');
2610 DEBUG(dbgs() << "HandlerStack: \n");
2611 for (int I = 0, E = HandlerStack.size(); I < E; ++I) {
2612 DEBUG(dbgs() << " ");
2613 print_name(HandlerStack[I]->getHandlerBlockOrFunc());
2614 DEBUG(dbgs() << '\n');
2616 DEBUG(dbgs() << "Actions: \n");
2617 for (int I = 0, E = Actions.size(); I < E; ++I) {
2618 DEBUG(dbgs() << " ");
2619 print_name(Actions[I]->getHandlerBlockOrFunc());
2620 DEBUG(dbgs() << '\n');
2622 int FirstMismatch = 0;
2623 for (int E = std::min(HandlerStack.size(), Actions.size()); FirstMismatch < E;
2625 if (HandlerStack[FirstMismatch]->getHandlerBlockOrFunc() !=
2626 Actions[FirstMismatch]->getHandlerBlockOrFunc())
2630 // Remove unmatched actions from the stack and process their EH states.
2631 popUnmatchedActions(FirstMismatch);
2633 DEBUG(dbgs() << "Pushing actions for CallSite: ");
2634 print_name(CS ? CS.getCalledValue() : nullptr);
2635 DEBUG(dbgs() << '\n');
2637 bool LastActionWasCatch = false;
2638 const LandingPadInst *LastRootLPad = nullptr;
2639 for (size_t I = FirstMismatch; I != Actions.size(); ++I) {
2640 // We can reuse eh states when pushing two catches for the same invoke.
2641 bool CurrActionIsCatch = isa<CatchHandler>(Actions[I].get());
2642 auto *Handler = cast<Function>(Actions[I]->getHandlerBlockOrFunc());
2643 // Various conditions can lead to a handler being popped from the
2644 // stack and re-pushed later. That shouldn't create a new state.
2645 // FIXME: Can code optimization lead to re-used handlers?
2646 if (FuncInfo.HandlerEnclosedState.count(Handler)) {
2647 // If we already assigned the state enclosed by this handler re-use it.
2648 Actions[I]->setEHState(FuncInfo.HandlerEnclosedState[Handler]);
2651 const LandingPadInst* RootLPad = FuncInfo.RootLPad[Handler];
2652 if (CurrActionIsCatch && LastActionWasCatch && RootLPad == LastRootLPad) {
2653 DEBUG(dbgs() << "setEHState for handler to " << currentEHNumber() << "\n");
2654 Actions[I]->setEHState(currentEHNumber());
2656 DEBUG(dbgs() << "createUnwindMapEntry(" << currentEHNumber() << ", ");
2657 print_name(Actions[I]->getHandlerBlockOrFunc());
2658 DEBUG(dbgs() << ") with EH state " << NextState << "\n");
2659 createUnwindMapEntry(currentEHNumber(), Actions[I].get());
2660 DEBUG(dbgs() << "setEHState for handler to " << NextState << "\n");
2661 Actions[I]->setEHState(NextState);
2664 HandlerStack.push_back(std::move(Actions[I]));
2665 LastActionWasCatch = CurrActionIsCatch;
2666 LastRootLPad = RootLPad;
2669 // This is used to defer numbering states for a handler until after the
2670 // last time it appears in an invoke action list.
2671 if (CS.isInvoke()) {
2672 for (int I = 0, E = HandlerStack.size(); I < E; ++I) {
2673 auto *Handler = cast<Function>(HandlerStack[I]->getHandlerBlockOrFunc());
2674 if (FuncInfo.LastInvoke[Handler] != cast<InvokeInst>(CS.getInstruction()))
2676 FuncInfo.LastInvokeVisited[Handler] = true;
2677 DEBUG(dbgs() << "Last invoke of ");
2678 print_name(Handler);
2679 DEBUG(dbgs() << " has been visited.\n");
2683 DEBUG(dbgs() << "In EHState " << currentEHNumber() << " for CallSite: ");
2684 print_name(CS ? CS.getCalledValue() : nullptr);
2685 DEBUG(dbgs() << '\n');
2688 void WinEHNumbering::popUnmatchedActions(int FirstMismatch) {
2689 // Don't recurse while we are looping over the handler stack. Instead, defer
2690 // the numbering of the catch handlers until we are done popping.
2691 SmallVector<CatchHandler *, 4> PoppedCatches;
2692 for (int I = HandlerStack.size() - 1; I >= FirstMismatch; --I) {
2693 std::unique_ptr<ActionHandler> Handler = HandlerStack.pop_back_val();
2694 if (isa<CatchHandler>(Handler.get()))
2695 PoppedCatches.push_back(cast<CatchHandler>(Handler.release()));
2698 int TryHigh = NextState - 1;
2699 int LastTryLowIdx = 0;
2700 for (int I = 0, E = PoppedCatches.size(); I != E; ++I) {
2701 CatchHandler *CH = PoppedCatches[I];
2702 DEBUG(dbgs() << "Popped handler with state " << CH->getEHState() << "\n");
2703 if (I + 1 == E || CH->getEHState() != PoppedCatches[I + 1]->getEHState()) {
2704 int TryLow = CH->getEHState();
2706 makeArrayRef(&PoppedCatches[LastTryLowIdx], I - LastTryLowIdx + 1);
2707 DEBUG(dbgs() << "createTryBlockMapEntry(" << TryLow << ", " << TryHigh);
2708 for (size_t J = 0; J < Handlers.size(); ++J) {
2709 DEBUG(dbgs() << ", ");
2710 print_name(Handlers[J]->getHandlerBlockOrFunc());
2712 DEBUG(dbgs() << ")\n");
2713 createTryBlockMapEntry(TryLow, TryHigh, Handlers);
2714 LastTryLowIdx = I + 1;
2718 for (CatchHandler *CH : PoppedCatches) {
2719 if (auto *F = dyn_cast<Function>(CH->getHandlerBlockOrFunc())) {
2720 if (FuncInfo.LastInvokeVisited[F]) {
2721 DEBUG(dbgs() << "Assigning base state " << NextState << " to ");
2723 DEBUG(dbgs() << '\n');
2724 FuncInfo.HandlerBaseState[F] = NextState;
2725 DEBUG(dbgs() << "createUnwindMapEntry(" << currentEHNumber()
2727 createUnwindMapEntry(currentEHNumber(), nullptr);
2729 calculateStateNumbers(*F);
2732 DEBUG(dbgs() << "Deferring handling of ");
2734 DEBUG(dbgs() << " until last invoke visited.\n");
2741 void WinEHNumbering::calculateStateNumbers(const Function &F) {
2742 auto I = VisitedHandlers.insert(&F);
2744 return; // We've already visited this handler, don't renumber it.
2746 int OldBaseState = CurrentBaseState;
2747 if (FuncInfo.HandlerBaseState.count(&F)) {
2748 CurrentBaseState = FuncInfo.HandlerBaseState[&F];
2751 size_t SavedHandlerStackSize = HandlerStack.size();
2753 DEBUG(dbgs() << "Calculating state numbers for: " << F.getName() << '\n');
2754 SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList;
2755 for (const BasicBlock &BB : F) {
2756 for (const Instruction &I : BB) {
2757 const auto *CI = dyn_cast<CallInst>(&I);
2758 if (!CI || CI->doesNotThrow())
2760 processCallSite(None, CI);
2762 const auto *II = dyn_cast<InvokeInst>(BB.getTerminator());
2765 const LandingPadInst *LPI = II->getLandingPadInst();
2766 auto *ActionsCall = dyn_cast<IntrinsicInst>(LPI->getNextNode());
2769 assert(ActionsCall->getIntrinsicID() == Intrinsic::eh_actions);
2770 parseEHActions(ActionsCall, ActionList);
2771 if (ActionList.empty())
2773 processCallSite(ActionList, II);
2775 FuncInfo.LandingPadStateMap[LPI] = currentEHNumber();
2776 DEBUG(dbgs() << "Assigning state " << currentEHNumber()
2777 << " to landing pad at " << LPI->getParent()->getName()
2781 // Pop any actions that were pushed on the stack for this function.
2782 popUnmatchedActions(SavedHandlerStackSize);
2784 DEBUG(dbgs() << "Assigning max state " << NextState - 1
2785 << " to " << F.getName() << '\n');
2786 FuncInfo.CatchHandlerMaxState[&F] = NextState - 1;
2788 CurrentBaseState = OldBaseState;
2791 // This function follows the same basic traversal as calculateStateNumbers
2792 // but it is necessary to identify the root landing pad associated
2793 // with each action before we start assigning state numbers.
2794 void WinEHNumbering::findActionRootLPads(const Function &F) {
2795 auto I = VisitedHandlers.insert(&F);
2797 return; // We've already visited this handler, don't revisit it.
2799 SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList;
2800 for (const BasicBlock &BB : F) {
2801 const auto *II = dyn_cast<InvokeInst>(BB.getTerminator());
2804 const LandingPadInst *LPI = II->getLandingPadInst();
2805 auto *ActionsCall = dyn_cast<IntrinsicInst>(LPI->getNextNode());
2809 assert(ActionsCall->getIntrinsicID() == Intrinsic::eh_actions);
2810 parseEHActions(ActionsCall, ActionList);
2811 if (ActionList.empty())
2813 for (int I = 0, E = ActionList.size(); I < E; ++I) {
2815 = dyn_cast<Function>(ActionList[I]->getHandlerBlockOrFunc())) {
2816 FuncInfo.LastInvoke[Handler] = II;
2817 // Don't replace the root landing pad if we previously saw this
2818 // handler in a different function.
2819 if (FuncInfo.RootLPad.count(Handler) &&
2820 FuncInfo.RootLPad[Handler]->getParent()->getParent() != &F)
2822 DEBUG(dbgs() << "Setting root lpad for ");
2823 print_name(Handler);
2824 DEBUG(dbgs() << " to " << LPI->getParent()->getName() << '\n');
2825 FuncInfo.RootLPad[Handler] = LPI;
2828 // Walk the actions again and look for nested handlers. This has to
2829 // happen after all of the actions have been processed in the current
2831 for (int I = 0, E = ActionList.size(); I < E; ++I)
2833 = dyn_cast<Function>(ActionList[I]->getHandlerBlockOrFunc()))
2834 findActionRootLPads(*Handler);
2839 void llvm::calculateWinCXXEHStateNumbers(const Function *ParentFn,
2840 WinEHFuncInfo &FuncInfo) {
2841 // Return if it's already been done.
2842 if (!FuncInfo.LandingPadStateMap.empty())
2845 WinEHNumbering Num(FuncInfo);
2846 Num.findActionRootLPads(*ParentFn);
2847 // The VisitedHandlers list is used by both findActionRootLPads and
2848 // calculateStateNumbers, but both functions need to visit all handlers.
2849 Num.VisitedHandlers.clear();
2850 Num.calculateStateNumbers(*ParentFn);
2851 // Pop everything on the handler stack.
2852 // It may be necessary to call this more than once because a handler can
2853 // be pushed on the stack as a result of clearing the stack.
2854 while (!Num.HandlerStack.empty())
2855 Num.processCallSite(None, ImmutableCallSite());