1 //===-- CodeGen/AsmPrinter/WinException.cpp - Dwarf Exception Impl ------===//
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 file contains support for writing Win64 exception info into asm files.
12 //===----------------------------------------------------------------------===//
14 #include "WinException.h"
15 #include "llvm/ADT/SmallString.h"
16 #include "llvm/ADT/StringExtras.h"
17 #include "llvm/ADT/Twine.h"
18 #include "llvm/CodeGen/AsmPrinter.h"
19 #include "llvm/CodeGen/MachineFrameInfo.h"
20 #include "llvm/CodeGen/MachineFunction.h"
21 #include "llvm/CodeGen/MachineModuleInfo.h"
22 #include "llvm/CodeGen/WinEHFuncInfo.h"
23 #include "llvm/IR/DataLayout.h"
24 #include "llvm/IR/Mangler.h"
25 #include "llvm/IR/Module.h"
26 #include "llvm/MC/MCAsmInfo.h"
27 #include "llvm/MC/MCContext.h"
28 #include "llvm/MC/MCExpr.h"
29 #include "llvm/MC/MCSection.h"
30 #include "llvm/MC/MCStreamer.h"
31 #include "llvm/MC/MCSymbol.h"
32 #include "llvm/MC/MCWin64EH.h"
33 #include "llvm/Support/Dwarf.h"
34 #include "llvm/Support/ErrorHandling.h"
35 #include "llvm/Support/FormattedStream.h"
36 #include "llvm/Target/TargetFrameLowering.h"
37 #include "llvm/Target/TargetLoweringObjectFile.h"
38 #include "llvm/Target/TargetOptions.h"
39 #include "llvm/Target/TargetRegisterInfo.h"
42 WinException::WinException(AsmPrinter *A) : EHStreamer(A) {
43 // MSVC's EH tables are always composed of 32-bit words. All known 64-bit
44 // platforms use an imagerel32 relocation to refer to symbols.
45 useImageRel32 = (A->getDataLayout().getPointerSizeInBits() == 64);
48 WinException::~WinException() {}
50 /// endModule - Emit all exception information that should come after the
52 void WinException::endModule() {
53 auto &OS = *Asm->OutStreamer;
54 const Module *M = MMI->getModule();
55 for (const Function &F : *M)
56 if (F.hasFnAttribute("safeseh"))
57 OS.EmitCOFFSafeSEH(Asm->getSymbol(&F));
60 void WinException::beginFunction(const MachineFunction *MF) {
61 shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
63 // If any landing pads survive, we need an EH table.
64 bool hasLandingPads = !MMI->getLandingPads().empty();
66 const Function *F = MF->getFunction();
67 const Function *ParentF = MMI->getWinEHParent(F);
69 shouldEmitMoves = Asm->needsSEHMoves();
71 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
72 unsigned PerEncoding = TLOF.getPersonalityEncoding();
73 const Function *Per = nullptr;
74 if (F->hasPersonalityFn())
75 Per = dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
77 bool forceEmitPersonality =
78 F->hasPersonalityFn() && !isNoOpWithoutInvoke(classifyEHPersonality(Per)) &&
79 F->needsUnwindTableEntry();
81 shouldEmitPersonality = forceEmitPersonality || (hasLandingPads &&
82 PerEncoding != dwarf::DW_EH_PE_omit && Per);
84 unsigned LSDAEncoding = TLOF.getLSDAEncoding();
85 shouldEmitLSDA = shouldEmitPersonality &&
86 LSDAEncoding != dwarf::DW_EH_PE_omit;
88 // If we're not using CFI, we don't want the CFI or the personality. If
89 // WinEHPrepare outlined something, we should emit the LSDA.
90 if (!Asm->MAI->usesWindowsCFI()) {
91 bool HasOutlinedChildren =
92 F->hasFnAttribute("wineh-parent") && F == ParentF;
93 shouldEmitLSDA = HasOutlinedChildren;
94 shouldEmitPersonality = false;
98 // If this was an outlined handler, we need to define the label corresponding
99 // to the offset of the parent frame relative to the stack pointer after the
102 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(ParentF);
103 auto I = FuncInfo.CatchHandlerParentFrameObjOffset.find(F);
104 if (I != FuncInfo.CatchHandlerParentFrameObjOffset.end()) {
105 MCSymbol *HandlerTypeParentFrameOffset =
106 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(
107 GlobalValue::getRealLinkageName(F->getName()));
109 // Emit a symbol assignment.
110 Asm->OutStreamer->EmitAssignment(
111 HandlerTypeParentFrameOffset,
112 MCConstantExpr::create(I->second, Asm->OutContext));
116 if (shouldEmitMoves || shouldEmitPersonality)
117 Asm->OutStreamer->EmitWinCFIStartProc(Asm->CurrentFnSym);
119 if (shouldEmitPersonality) {
120 const MCSymbol *PersHandlerSym =
121 TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
122 Asm->OutStreamer->EmitWinEHHandler(PersHandlerSym, true, true);
126 /// endFunction - Gather and emit post-function exception information.
128 void WinException::endFunction(const MachineFunction *MF) {
129 if (!shouldEmitPersonality && !shouldEmitMoves && !shouldEmitLSDA)
132 const Function *F = MF->getFunction();
133 EHPersonality Per = EHPersonality::Unknown;
134 if (F->hasPersonalityFn())
135 Per = classifyEHPersonality(F->getPersonalityFn());
137 // Get rid of any dead landing pads if we're not using a Windows EH scheme. In
138 // Windows EH schemes, the landing pad is not actually reachable. It only
139 // exists so that we can emit the right table data.
140 if (!isMSVCEHPersonality(Per))
141 MMI->TidyLandingPads();
143 if (shouldEmitPersonality || shouldEmitLSDA) {
144 Asm->OutStreamer->PushSection();
146 if (shouldEmitMoves || shouldEmitPersonality) {
147 // Emit an UNWIND_INFO struct describing the prologue.
148 Asm->OutStreamer->EmitWinEHHandlerData();
150 // Just switch sections to the right xdata section. This use of
151 // CurrentFnSym assumes that we only emit the LSDA when ending the parent
153 MCSection *XData = WinEH::UnwindEmitter::getXDataSection(
154 Asm->CurrentFnSym, Asm->OutContext);
155 Asm->OutStreamer->SwitchSection(XData);
158 // Emit the tables appropriate to the personality function in use. If we
159 // don't recognize the personality, assume it uses an Itanium-style LSDA.
160 if (Per == EHPersonality::MSVC_Win64SEH)
161 emitCSpecificHandlerTable();
162 else if (Per == EHPersonality::MSVC_X86SEH)
163 emitExceptHandlerTable(MF);
164 else if (Per == EHPersonality::MSVC_CXX)
165 emitCXXFrameHandler3Table(MF);
167 emitExceptionTable();
169 Asm->OutStreamer->PopSection();
173 Asm->OutStreamer->EmitWinCFIEndProc();
176 const MCExpr *WinException::create32bitRef(const MCSymbol *Value) {
178 return MCConstantExpr::create(0, Asm->OutContext);
179 return MCSymbolRefExpr::create(Value, useImageRel32
180 ? MCSymbolRefExpr::VK_COFF_IMGREL32
181 : MCSymbolRefExpr::VK_None,
185 const MCExpr *WinException::create32bitRef(const Value *V) {
187 return MCConstantExpr::create(0, Asm->OutContext);
188 return create32bitRef(Asm->getSymbol(cast<GlobalValue>(V)));
191 /// Emit the language-specific data that __C_specific_handler expects. This
192 /// handler lives in the x64 Microsoft C runtime and allows catching or cleaning
193 /// up after faults with __try, __except, and __finally. The typeinfo values
194 /// are not really RTTI data, but pointers to filter functions that return an
195 /// integer (1, 0, or -1) indicating how to handle the exception. For __finally
196 /// blocks and other cleanups, the landing pad label is zero, and the filter
197 /// function is actually a cleanup handler with the same prototype. A catch-all
198 /// entry is modeled with a null filter function field and a non-zero landing
201 /// Possible filter function return values:
202 /// EXCEPTION_EXECUTE_HANDLER (1):
203 /// Jump to the landing pad label after cleanups.
204 /// EXCEPTION_CONTINUE_SEARCH (0):
205 /// Continue searching this table or continue unwinding.
206 /// EXCEPTION_CONTINUE_EXECUTION (-1):
207 /// Resume execution at the trapping PC.
209 /// Inferred table structure:
213 /// imagerel32 LabelStart;
214 /// imagerel32 LabelEnd;
215 /// imagerel32 FilterOrFinally; // One means catch-all.
216 /// imagerel32 LabelLPad; // Zero means __finally.
217 /// } Entries[NumEntries];
219 void WinException::emitCSpecificHandlerTable() {
220 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
222 // Simplifying assumptions for first implementation:
223 // - Cleanups are not implemented.
224 // - Filters are not implemented.
226 // The Itanium LSDA table sorts similar landing pads together to simplify the
227 // actions table, but we don't need that.
228 SmallVector<const LandingPadInfo *, 64> LandingPads;
229 LandingPads.reserve(PadInfos.size());
230 for (const auto &LP : PadInfos)
231 LandingPads.push_back(&LP);
233 // Compute label ranges for call sites as we would for the Itanium LSDA, but
234 // use an all zero action table because we aren't using these actions.
235 SmallVector<unsigned, 64> FirstActions;
236 FirstActions.resize(LandingPads.size());
237 SmallVector<CallSiteEntry, 64> CallSites;
238 computeCallSiteTable(CallSites, LandingPads, FirstActions);
240 MCSymbol *EHFuncBeginSym = Asm->getFunctionBegin();
241 MCSymbol *EHFuncEndSym = Asm->getFunctionEnd();
243 // Emit the number of table entries.
244 unsigned NumEntries = 0;
245 for (const CallSiteEntry &CSE : CallSites) {
247 continue; // Ignore gaps.
248 NumEntries += CSE.LPad->SEHHandlers.size();
250 Asm->OutStreamer->EmitIntValue(NumEntries, 4);
252 // If there are no actions, we don't need to iterate again.
256 // Emit the four-label records for each call site entry. The table has to be
257 // sorted in layout order, and the call sites should already be sorted.
258 for (const CallSiteEntry &CSE : CallSites) {
259 // Ignore gaps. Unlike the Itanium model, unwinding through a frame without
260 // an EH table entry will propagate the exception rather than terminating
264 const LandingPadInfo *LPad = CSE.LPad;
266 // Compute the label range. We may reuse the function begin and end labels
267 // rather than forming new ones.
268 const MCExpr *Begin =
269 create32bitRef(CSE.BeginLabel ? CSE.BeginLabel : EHFuncBeginSym);
272 // The interval is half-open, so we have to add one to include the return
273 // address of the last invoke in the range.
274 End = MCBinaryExpr::createAdd(create32bitRef(CSE.EndLabel),
275 MCConstantExpr::create(1, Asm->OutContext),
278 End = create32bitRef(EHFuncEndSym);
281 // Emit an entry for each action.
282 for (SEHHandler Handler : LPad->SEHHandlers) {
283 Asm->OutStreamer->EmitValue(Begin, 4);
284 Asm->OutStreamer->EmitValue(End, 4);
286 // Emit the filter or finally function pointer, if present. Otherwise,
287 // emit '1' to indicate a catch-all.
288 const Function *F = Handler.FilterOrFinally;
290 Asm->OutStreamer->EmitValue(create32bitRef(Asm->getSymbol(F)), 4);
292 Asm->OutStreamer->EmitIntValue(1, 4);
294 // Emit the recovery address, if present. Otherwise, this must be a
296 const BlockAddress *BA = Handler.RecoverBA;
298 Asm->OutStreamer->EmitValue(
299 create32bitRef(Asm->GetBlockAddressSymbol(BA)), 4);
301 Asm->OutStreamer->EmitIntValue(0, 4);
306 void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
307 const Function *F = MF->getFunction();
308 const Function *ParentF = MMI->getWinEHParent(F);
309 auto &OS = *Asm->OutStreamer;
310 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(ParentF);
312 StringRef ParentLinkageName =
313 GlobalValue::getRealLinkageName(ParentF->getName());
315 MCSymbol *FuncInfoXData = nullptr;
316 if (shouldEmitPersonality) {
317 FuncInfoXData = Asm->OutContext.getOrCreateSymbol(
318 Twine("$cppxdata$", ParentLinkageName));
319 OS.EmitValue(create32bitRef(FuncInfoXData), 4);
321 extendIP2StateTable(MF, ParentF, FuncInfo);
323 // Defer emission until we've visited the parent function and all the catch
324 // handlers. Cleanups don't contribute to the ip2state table, so don't count
326 if (ParentF != F && !FuncInfo.CatchHandlerMaxState.count(F))
328 ++FuncInfo.NumIPToStateFuncsVisited;
329 if (FuncInfo.NumIPToStateFuncsVisited != FuncInfo.CatchHandlerMaxState.size())
332 FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(ParentLinkageName);
333 emitEHRegistrationOffsetLabel(FuncInfo, ParentLinkageName);
336 MCSymbol *UnwindMapXData = nullptr;
337 MCSymbol *TryBlockMapXData = nullptr;
338 MCSymbol *IPToStateXData = nullptr;
339 if (!FuncInfo.UnwindMap.empty())
340 UnwindMapXData = Asm->OutContext.getOrCreateSymbol(
341 Twine("$stateUnwindMap$", ParentLinkageName));
342 if (!FuncInfo.TryBlockMap.empty())
343 TryBlockMapXData = Asm->OutContext.getOrCreateSymbol(
344 Twine("$tryMap$", ParentLinkageName));
345 if (!FuncInfo.IPToStateList.empty())
346 IPToStateXData = Asm->OutContext.getOrCreateSymbol(
347 Twine("$ip2state$", ParentLinkageName));
350 // uint32_t MagicNumber
352 // UnwindMapEntry *UnwindMap;
353 // uint32_t NumTryBlocks;
354 // TryBlockMapEntry *TryBlockMap;
355 // uint32_t IPMapEntries; // always 0 for x86
356 // IPToStateMapEntry *IPToStateMap; // always 0 for x86
357 // uint32_t UnwindHelp; // non-x86 only
358 // ESTypeList *ESTypeList;
361 // EHFlags & 1 -> Synchronous exceptions only, no async exceptions.
362 // EHFlags & 2 -> ???
363 // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue.
364 OS.EmitValueToAlignment(4);
365 OS.EmitLabel(FuncInfoXData);
366 OS.EmitIntValue(0x19930522, 4); // MagicNumber
367 OS.EmitIntValue(FuncInfo.UnwindMap.size(), 4); // MaxState
368 OS.EmitValue(create32bitRef(UnwindMapXData), 4); // UnwindMap
369 OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4); // NumTryBlocks
370 OS.EmitValue(create32bitRef(TryBlockMapXData), 4); // TryBlockMap
371 OS.EmitIntValue(FuncInfo.IPToStateList.size(), 4); // IPMapEntries
372 OS.EmitValue(create32bitRef(IPToStateXData), 4); // IPToStateMap
373 if (Asm->MAI->usesWindowsCFI())
374 OS.EmitIntValue(FuncInfo.UnwindHelpFrameOffset, 4); // UnwindHelp
375 OS.EmitIntValue(0, 4); // ESTypeList
376 OS.EmitIntValue(1, 4); // EHFlags
382 if (UnwindMapXData) {
383 OS.EmitLabel(UnwindMapXData);
384 for (const WinEHUnwindMapEntry &UME : FuncInfo.UnwindMap) {
385 OS.EmitIntValue(UME.ToState, 4); // ToState
386 OS.EmitValue(create32bitRef(UME.Cleanup), 4); // Action
393 // int32_t CatchHigh;
394 // int32_t NumCatches;
395 // HandlerType *HandlerArray;
397 if (TryBlockMapXData) {
398 OS.EmitLabel(TryBlockMapXData);
399 SmallVector<MCSymbol *, 1> HandlerMaps;
400 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
401 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
402 MCSymbol *HandlerMapXData = nullptr;
404 if (!TBME.HandlerArray.empty())
406 Asm->OutContext.getOrCreateSymbol(Twine("$handlerMap$")
409 .concat(ParentLinkageName));
411 HandlerMaps.push_back(HandlerMapXData);
414 for (WinEHHandlerType &HT : TBME.HandlerArray)
417 FuncInfo.CatchHandlerMaxState[cast<Function>(HT.Handler)]);
419 assert(TBME.TryLow <= TBME.TryHigh);
420 OS.EmitIntValue(TBME.TryLow, 4); // TryLow
421 OS.EmitIntValue(TBME.TryHigh, 4); // TryHigh
422 OS.EmitIntValue(CatchHigh, 4); // CatchHigh
423 OS.EmitIntValue(TBME.HandlerArray.size(), 4); // NumCatches
424 OS.EmitValue(create32bitRef(HandlerMapXData), 4); // HandlerArray
427 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
428 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
429 MCSymbol *HandlerMapXData = HandlerMaps[I];
430 if (!HandlerMapXData)
433 // int32_t Adjectives;
434 // TypeDescriptor *Type;
435 // int32_t CatchObjOffset;
436 // void (*Handler)();
437 // int32_t ParentFrameOffset; // x64 only
439 OS.EmitLabel(HandlerMapXData);
440 for (const WinEHHandlerType &HT : TBME.HandlerArray) {
441 // Get the frame escape label with the offset of the catch object. If
442 // the index is -1, then there is no catch object, and we should emit an
443 // offset of zero, indicating that no copy will occur.
444 const MCExpr *FrameAllocOffsetRef = nullptr;
445 if (HT.CatchObjRecoverIdx >= 0) {
446 MCSymbol *FrameAllocOffset =
447 Asm->OutContext.getOrCreateFrameAllocSymbol(
448 GlobalValue::getRealLinkageName(ParentF->getName()),
449 HT.CatchObjRecoverIdx);
450 FrameAllocOffsetRef = MCSymbolRefExpr::create(
451 FrameAllocOffset, MCSymbolRefExpr::VK_None, Asm->OutContext);
453 FrameAllocOffsetRef = MCConstantExpr::create(0, Asm->OutContext);
456 OS.EmitIntValue(HT.Adjectives, 4); // Adjectives
457 OS.EmitValue(create32bitRef(HT.TypeDescriptor), 4); // Type
458 OS.EmitValue(FrameAllocOffsetRef, 4); // CatchObjOffset
459 OS.EmitValue(create32bitRef(HT.Handler), 4); // Handler
461 if (shouldEmitPersonality) {
462 MCSymbol *ParentFrameOffset =
463 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(
464 GlobalValue::getRealLinkageName(HT.Handler->getName()));
465 const MCSymbolRefExpr *ParentFrameOffsetRef = MCSymbolRefExpr::create(
466 ParentFrameOffset, Asm->OutContext);
467 OS.EmitValue(ParentFrameOffsetRef, 4); // ParentFrameOffset
473 // IPToStateMapEntry {
477 if (IPToStateXData) {
478 OS.EmitLabel(IPToStateXData);
479 for (auto &IPStatePair : FuncInfo.IPToStateList) {
480 OS.EmitValue(create32bitRef(IPStatePair.first), 4); // IP
481 OS.EmitIntValue(IPStatePair.second, 4); // State
486 void WinException::extendIP2StateTable(const MachineFunction *MF,
487 const Function *ParentF,
488 WinEHFuncInfo &FuncInfo) {
489 const Function *F = MF->getFunction();
491 // The Itanium LSDA table sorts similar landing pads together to simplify the
492 // actions table, but we don't need that.
493 SmallVector<const LandingPadInfo *, 64> LandingPads;
494 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
495 LandingPads.reserve(PadInfos.size());
496 for (const auto &LP : PadInfos)
497 LandingPads.push_back(&LP);
500 computePadMap(LandingPads, PadMap);
502 // The end label of the previous invoke or nounwind try-range.
503 MCSymbol *LastLabel = Asm->getFunctionBegin();
505 // Whether there is a potentially throwing instruction (currently this means
506 // an ordinary call) between the end of the previous try-range and now.
507 bool SawPotentiallyThrowing = false;
509 int LastEHState = -2;
511 // The parent function and the catch handlers contribute to the 'ip2state'
514 // Include ip2state entries for the beginning of the main function and
515 // for catch handler functions.
517 FuncInfo.IPToStateList.push_back(std::make_pair(LastLabel, -1));
519 } else if (FuncInfo.HandlerBaseState.count(F)) {
520 FuncInfo.IPToStateList.push_back(
521 std::make_pair(LastLabel, FuncInfo.HandlerBaseState[F]));
522 LastEHState = FuncInfo.HandlerBaseState[F];
524 for (const auto &MBB : *MF) {
525 for (const auto &MI : MBB) {
526 if (!MI.isEHLabel()) {
528 SawPotentiallyThrowing |= !callToNoUnwindFunction(&MI);
532 // End of the previous try-range?
533 MCSymbol *BeginLabel = MI.getOperand(0).getMCSymbol();
534 if (BeginLabel == LastLabel)
535 SawPotentiallyThrowing = false;
537 // Beginning of a new try-range?
538 RangeMapType::const_iterator L = PadMap.find(BeginLabel);
539 if (L == PadMap.end())
540 // Nope, it was just some random label.
543 const PadRange &P = L->second;
544 const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
545 assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
546 "Inconsistent landing pad map!");
548 // FIXME: Should this be using FuncInfo.HandlerBaseState?
549 if (SawPotentiallyThrowing && LastEHState != -1) {
550 FuncInfo.IPToStateList.push_back(std::make_pair(LastLabel, -1));
551 SawPotentiallyThrowing = false;
555 if (LandingPad->WinEHState != LastEHState)
556 FuncInfo.IPToStateList.push_back(
557 std::make_pair(BeginLabel, LandingPad->WinEHState));
558 LastEHState = LandingPad->WinEHState;
559 LastLabel = LandingPad->EndLabels[P.RangeIndex];
564 void WinException::emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo,
565 StringRef FLinkageName) {
566 // Outlined helpers called by the EH runtime need to know the offset of the EH
567 // registration in order to recover the parent frame pointer. Now that we know
568 // we've code generated the parent, we can emit the label assignment that
569 // those helpers use to get the offset of the registration node.
570 assert(FuncInfo.EHRegNodeEscapeIndex != INT_MAX &&
571 "no EH reg node localescape index");
572 MCSymbol *ParentFrameOffset =
573 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(FLinkageName);
574 MCSymbol *RegistrationOffsetSym = Asm->OutContext.getOrCreateFrameAllocSymbol(
575 FLinkageName, FuncInfo.EHRegNodeEscapeIndex);
576 const MCExpr *RegistrationOffsetSymRef =
577 MCSymbolRefExpr::create(RegistrationOffsetSym, Asm->OutContext);
578 Asm->OutStreamer->EmitAssignment(ParentFrameOffset, RegistrationOffsetSymRef);
581 /// Emit the language-specific data that _except_handler3 and 4 expect. This is
582 /// functionally equivalent to the __C_specific_handler table, except it is
583 /// indexed by state number instead of IP.
584 void WinException::emitExceptHandlerTable(const MachineFunction *MF) {
585 MCStreamer &OS = *Asm->OutStreamer;
586 const Function *F = MF->getFunction();
587 StringRef FLinkageName = GlobalValue::getRealLinkageName(F->getName());
589 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
590 emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
592 // Emit the __ehtable label that we use for llvm.x86.seh.lsda.
593 MCSymbol *LSDALabel = Asm->OutContext.getOrCreateLSDASymbol(FLinkageName);
594 OS.EmitValueToAlignment(4);
595 OS.EmitLabel(LSDALabel);
597 const Function *Per =
598 dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
599 StringRef PerName = Per->getName();
601 if (PerName == "_except_handler4") {
602 // The LSDA for _except_handler4 starts with this struct, followed by the
605 // struct EH4ScopeTable {
606 // int32_t GSCookieOffset;
607 // int32_t GSCookieXOROffset;
608 // int32_t EHCookieOffset;
609 // int32_t EHCookieXOROffset;
610 // ScopeTableEntry ScopeRecord[];
613 // Only the EHCookieOffset field appears to vary, and it appears to be the
614 // offset from the final saved SP value to the retaddr.
615 OS.EmitIntValue(-2, 4);
616 OS.EmitIntValue(0, 4);
618 OS.EmitIntValue(9999, 4);
619 OS.EmitIntValue(0, 4);
623 // Build a list of pointers to LandingPadInfos and then sort by WinEHState.
624 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
625 SmallVector<const LandingPadInfo *, 4> LPads;
626 LPads.reserve((PadInfos.size()));
627 for (const LandingPadInfo &LPInfo : PadInfos)
628 LPads.push_back(&LPInfo);
629 std::sort(LPads.begin(), LPads.end(),
630 [](const LandingPadInfo *L, const LandingPadInfo *R) {
631 return L->WinEHState < R->WinEHState;
634 // For each action in each lpad, emit one of these:
635 // struct ScopeTableEntry {
636 // int32_t EnclosingLevel;
637 // int32_t (__cdecl *Filter)();
638 // void *HandlerOrFinally;
641 // The "outermost" action will use BaseState as its enclosing level. Each
642 // other action will refer to the previous state as its enclosing level.
644 for (const LandingPadInfo *LPInfo : LPads) {
645 int EnclosingLevel = BaseState;
646 assert(CurState + int(LPInfo->SEHHandlers.size()) - 1 ==
647 LPInfo->WinEHState &&
648 "gaps in the SEH scope table");
649 for (auto I = LPInfo->SEHHandlers.rbegin(), E = LPInfo->SEHHandlers.rend();
651 const SEHHandler &Handler = *I;
652 const BlockAddress *BA = Handler.RecoverBA;
653 const Function *F = Handler.FilterOrFinally;
654 assert(F && "cannot catch all in 32-bit SEH without filter function");
655 const MCExpr *FilterOrNull =
656 create32bitRef(BA ? Asm->getSymbol(F) : nullptr);
657 const MCExpr *ExceptOrFinally = create32bitRef(
658 BA ? Asm->GetBlockAddressSymbol(BA) : Asm->getSymbol(F));
660 OS.EmitIntValue(EnclosingLevel, 4);
661 OS.EmitValue(FilterOrNull, 4);
662 OS.EmitValue(ExceptOrFinally, 4);
664 // The next state unwinds to this state.
665 EnclosingLevel = CurState;