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 = MMI->getPersonality();
75 shouldEmitPersonality = hasLandingPads &&
76 PerEncoding != dwarf::DW_EH_PE_omit && Per;
78 unsigned LSDAEncoding = TLOF.getLSDAEncoding();
79 shouldEmitLSDA = shouldEmitPersonality &&
80 LSDAEncoding != dwarf::DW_EH_PE_omit;
82 // If we're not using CFI, we don't want the CFI or the personality. Emit the
83 // LSDA if this is the parent function.
84 if (!Asm->MAI->usesWindowsCFI()) {
85 shouldEmitLSDA = (hasLandingPads && F == ParentF);
86 shouldEmitPersonality = false;
90 // If this was an outlined handler, we need to define the label corresponding
91 // to the offset of the parent frame relative to the stack pointer after the
94 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(ParentF);
95 auto I = FuncInfo.CatchHandlerParentFrameObjOffset.find(F);
96 if (I != FuncInfo.CatchHandlerParentFrameObjOffset.end()) {
97 MCSymbol *HandlerTypeParentFrameOffset =
98 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(
99 GlobalValue::getRealLinkageName(F->getName()));
101 // Emit a symbol assignment.
102 Asm->OutStreamer->EmitAssignment(
103 HandlerTypeParentFrameOffset,
104 MCConstantExpr::create(I->second, Asm->OutContext));
108 if (shouldEmitMoves || shouldEmitPersonality)
109 Asm->OutStreamer->EmitWinCFIStartProc(Asm->CurrentFnSym);
111 if (shouldEmitPersonality) {
112 const MCSymbol *PersHandlerSym =
113 TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
114 Asm->OutStreamer->EmitWinEHHandler(PersHandlerSym, true, true);
118 /// endFunction - Gather and emit post-function exception information.
120 void WinException::endFunction(const MachineFunction *MF) {
121 if (!shouldEmitPersonality && !shouldEmitMoves && !shouldEmitLSDA)
124 EHPersonality Per = MMI->getPersonalityType();
126 // Get rid of any dead landing pads if we're not using a Windows EH scheme. In
127 // Windows EH schemes, the landing pad is not actually reachable. It only
128 // exists so that we can emit the right table data.
129 if (!isMSVCEHPersonality(Per))
130 MMI->TidyLandingPads();
132 if (shouldEmitPersonality || shouldEmitLSDA) {
133 Asm->OutStreamer->PushSection();
135 if (shouldEmitMoves || shouldEmitPersonality) {
136 // Emit an UNWIND_INFO struct describing the prologue.
137 Asm->OutStreamer->EmitWinEHHandlerData();
139 // Just switch sections to the right xdata section. This use of
140 // CurrentFnSym assumes that we only emit the LSDA when ending the parent
142 MCSection *XData = WinEH::UnwindEmitter::getXDataSection(
143 Asm->CurrentFnSym, Asm->OutContext);
144 Asm->OutStreamer->SwitchSection(XData);
147 // Emit the tables appropriate to the personality function in use. If we
148 // don't recognize the personality, assume it uses an Itanium-style LSDA.
149 if (Per == EHPersonality::MSVC_Win64SEH)
150 emitCSpecificHandlerTable();
151 else if (Per == EHPersonality::MSVC_X86SEH)
152 emitExceptHandlerTable(MF);
153 else if (Per == EHPersonality::MSVC_CXX)
154 emitCXXFrameHandler3Table(MF);
156 emitExceptionTable();
158 Asm->OutStreamer->PopSection();
162 Asm->OutStreamer->EmitWinCFIEndProc();
165 const MCExpr *WinException::create32bitRef(const MCSymbol *Value) {
167 return MCConstantExpr::create(0, Asm->OutContext);
168 return MCSymbolRefExpr::create(Value, useImageRel32
169 ? MCSymbolRefExpr::VK_COFF_IMGREL32
170 : MCSymbolRefExpr::VK_None,
174 const MCExpr *WinException::create32bitRef(const GlobalValue *GV) {
176 return MCConstantExpr::create(0, Asm->OutContext);
177 return create32bitRef(Asm->getSymbol(GV));
180 /// Emit the language-specific data that __C_specific_handler expects. This
181 /// handler lives in the x64 Microsoft C runtime and allows catching or cleaning
182 /// up after faults with __try, __except, and __finally. The typeinfo values
183 /// are not really RTTI data, but pointers to filter functions that return an
184 /// integer (1, 0, or -1) indicating how to handle the exception. For __finally
185 /// blocks and other cleanups, the landing pad label is zero, and the filter
186 /// function is actually a cleanup handler with the same prototype. A catch-all
187 /// entry is modeled with a null filter function field and a non-zero landing
190 /// Possible filter function return values:
191 /// EXCEPTION_EXECUTE_HANDLER (1):
192 /// Jump to the landing pad label after cleanups.
193 /// EXCEPTION_CONTINUE_SEARCH (0):
194 /// Continue searching this table or continue unwinding.
195 /// EXCEPTION_CONTINUE_EXECUTION (-1):
196 /// Resume execution at the trapping PC.
198 /// Inferred table structure:
202 /// imagerel32 LabelStart;
203 /// imagerel32 LabelEnd;
204 /// imagerel32 FilterOrFinally; // One means catch-all.
205 /// imagerel32 LabelLPad; // Zero means __finally.
206 /// } Entries[NumEntries];
208 void WinException::emitCSpecificHandlerTable() {
209 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
211 // Simplifying assumptions for first implementation:
212 // - Cleanups are not implemented.
213 // - Filters are not implemented.
215 // The Itanium LSDA table sorts similar landing pads together to simplify the
216 // actions table, but we don't need that.
217 SmallVector<const LandingPadInfo *, 64> LandingPads;
218 LandingPads.reserve(PadInfos.size());
219 for (const auto &LP : PadInfos)
220 LandingPads.push_back(&LP);
222 // Compute label ranges for call sites as we would for the Itanium LSDA, but
223 // use an all zero action table because we aren't using these actions.
224 SmallVector<unsigned, 64> FirstActions;
225 FirstActions.resize(LandingPads.size());
226 SmallVector<CallSiteEntry, 64> CallSites;
227 computeCallSiteTable(CallSites, LandingPads, FirstActions);
229 MCSymbol *EHFuncBeginSym = Asm->getFunctionBegin();
230 MCSymbol *EHFuncEndSym = Asm->getFunctionEnd();
232 // Emit the number of table entries.
233 unsigned NumEntries = 0;
234 for (const CallSiteEntry &CSE : CallSites) {
236 continue; // Ignore gaps.
237 NumEntries += CSE.LPad->SEHHandlers.size();
239 Asm->OutStreamer->EmitIntValue(NumEntries, 4);
241 // If there are no actions, we don't need to iterate again.
245 // Emit the four-label records for each call site entry. The table has to be
246 // sorted in layout order, and the call sites should already be sorted.
247 for (const CallSiteEntry &CSE : CallSites) {
248 // Ignore gaps. Unlike the Itanium model, unwinding through a frame without
249 // an EH table entry will propagate the exception rather than terminating
253 const LandingPadInfo *LPad = CSE.LPad;
255 // Compute the label range. We may reuse the function begin and end labels
256 // rather than forming new ones.
257 const MCExpr *Begin =
258 create32bitRef(CSE.BeginLabel ? CSE.BeginLabel : EHFuncBeginSym);
261 // The interval is half-open, so we have to add one to include the return
262 // address of the last invoke in the range.
263 End = MCBinaryExpr::createAdd(create32bitRef(CSE.EndLabel),
264 MCConstantExpr::create(1, Asm->OutContext),
267 End = create32bitRef(EHFuncEndSym);
270 // Emit an entry for each action.
271 for (SEHHandler Handler : LPad->SEHHandlers) {
272 Asm->OutStreamer->EmitValue(Begin, 4);
273 Asm->OutStreamer->EmitValue(End, 4);
275 // Emit the filter or finally function pointer, if present. Otherwise,
276 // emit '1' to indicate a catch-all.
277 const Function *F = Handler.FilterOrFinally;
279 Asm->OutStreamer->EmitValue(create32bitRef(Asm->getSymbol(F)), 4);
281 Asm->OutStreamer->EmitIntValue(1, 4);
283 // Emit the recovery address, if present. Otherwise, this must be a
285 const BlockAddress *BA = Handler.RecoverBA;
287 Asm->OutStreamer->EmitValue(
288 create32bitRef(Asm->GetBlockAddressSymbol(BA)), 4);
290 Asm->OutStreamer->EmitIntValue(0, 4);
295 void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
296 const Function *F = MF->getFunction();
297 const Function *ParentF = MMI->getWinEHParent(F);
298 auto &OS = *Asm->OutStreamer;
299 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(ParentF);
301 StringRef ParentLinkageName =
302 GlobalValue::getRealLinkageName(ParentF->getName());
304 MCSymbol *FuncInfoXData = nullptr;
305 if (shouldEmitPersonality) {
306 FuncInfoXData = Asm->OutContext.getOrCreateSymbol(
307 Twine("$cppxdata$", ParentLinkageName));
308 OS.EmitValue(create32bitRef(FuncInfoXData), 4);
310 extendIP2StateTable(MF, ParentF, FuncInfo);
312 // Defer emission until we've visited the parent function and all the catch
313 // handlers. Cleanups don't contribute to the ip2state table, so don't count
315 if (ParentF != F && !FuncInfo.CatchHandlerMaxState.count(F))
317 ++FuncInfo.NumIPToStateFuncsVisited;
318 if (FuncInfo.NumIPToStateFuncsVisited != FuncInfo.CatchHandlerMaxState.size())
321 FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(ParentLinkageName);
322 emitEHRegistrationOffsetLabel(FuncInfo, ParentLinkageName);
325 MCSymbol *UnwindMapXData = nullptr;
326 MCSymbol *TryBlockMapXData = nullptr;
327 MCSymbol *IPToStateXData = nullptr;
328 if (!FuncInfo.UnwindMap.empty())
329 UnwindMapXData = Asm->OutContext.getOrCreateSymbol(
330 Twine("$stateUnwindMap$", ParentLinkageName));
331 if (!FuncInfo.TryBlockMap.empty())
332 TryBlockMapXData = Asm->OutContext.getOrCreateSymbol(
333 Twine("$tryMap$", ParentLinkageName));
334 if (!FuncInfo.IPToStateList.empty())
335 IPToStateXData = Asm->OutContext.getOrCreateSymbol(
336 Twine("$ip2state$", ParentLinkageName));
339 // uint32_t MagicNumber
341 // UnwindMapEntry *UnwindMap;
342 // uint32_t NumTryBlocks;
343 // TryBlockMapEntry *TryBlockMap;
344 // uint32_t IPMapEntries; // always 0 for x86
345 // IPToStateMapEntry *IPToStateMap; // always 0 for x86
346 // uint32_t UnwindHelp; // non-x86 only
347 // ESTypeList *ESTypeList;
350 // EHFlags & 1 -> Synchronous exceptions only, no async exceptions.
351 // EHFlags & 2 -> ???
352 // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue.
353 OS.EmitValueToAlignment(4);
354 OS.EmitLabel(FuncInfoXData);
355 OS.EmitIntValue(0x19930522, 4); // MagicNumber
356 OS.EmitIntValue(FuncInfo.UnwindMap.size(), 4); // MaxState
357 OS.EmitValue(create32bitRef(UnwindMapXData), 4); // UnwindMap
358 OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4); // NumTryBlocks
359 OS.EmitValue(create32bitRef(TryBlockMapXData), 4); // TryBlockMap
360 OS.EmitIntValue(FuncInfo.IPToStateList.size(), 4); // IPMapEntries
361 OS.EmitValue(create32bitRef(IPToStateXData), 4); // IPToStateMap
362 if (Asm->MAI->usesWindowsCFI())
363 OS.EmitIntValue(FuncInfo.UnwindHelpFrameOffset, 4); // UnwindHelp
364 OS.EmitIntValue(0, 4); // ESTypeList
365 OS.EmitIntValue(1, 4); // EHFlags
371 if (UnwindMapXData) {
372 OS.EmitLabel(UnwindMapXData);
373 for (const WinEHUnwindMapEntry &UME : FuncInfo.UnwindMap) {
374 OS.EmitIntValue(UME.ToState, 4); // ToState
375 OS.EmitValue(create32bitRef(UME.Cleanup), 4); // Action
382 // int32_t CatchHigh;
383 // int32_t NumCatches;
384 // HandlerType *HandlerArray;
386 if (TryBlockMapXData) {
387 OS.EmitLabel(TryBlockMapXData);
388 SmallVector<MCSymbol *, 1> HandlerMaps;
389 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
390 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
391 MCSymbol *HandlerMapXData = nullptr;
393 if (!TBME.HandlerArray.empty())
395 Asm->OutContext.getOrCreateSymbol(Twine("$handlerMap$")
398 .concat(ParentLinkageName));
400 HandlerMaps.push_back(HandlerMapXData);
403 for (WinEHHandlerType &HT : TBME.HandlerArray)
405 std::max(CatchHigh, FuncInfo.CatchHandlerMaxState[HT.Handler]);
407 assert(TBME.TryLow <= TBME.TryHigh);
408 OS.EmitIntValue(TBME.TryLow, 4); // TryLow
409 OS.EmitIntValue(TBME.TryHigh, 4); // TryHigh
410 OS.EmitIntValue(CatchHigh, 4); // CatchHigh
411 OS.EmitIntValue(TBME.HandlerArray.size(), 4); // NumCatches
412 OS.EmitValue(create32bitRef(HandlerMapXData), 4); // HandlerArray
415 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
416 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
417 MCSymbol *HandlerMapXData = HandlerMaps[I];
418 if (!HandlerMapXData)
421 // int32_t Adjectives;
422 // TypeDescriptor *Type;
423 // int32_t CatchObjOffset;
424 // void (*Handler)();
425 // int32_t ParentFrameOffset; // x64 only
427 OS.EmitLabel(HandlerMapXData);
428 for (const WinEHHandlerType &HT : TBME.HandlerArray) {
429 // Get the frame escape label with the offset of the catch object. If
430 // the index is -1, then there is no catch object, and we should emit an
431 // offset of zero, indicating that no copy will occur.
432 const MCExpr *FrameAllocOffsetRef = nullptr;
433 if (HT.CatchObjRecoverIdx >= 0) {
434 MCSymbol *FrameAllocOffset =
435 Asm->OutContext.getOrCreateFrameAllocSymbol(
436 GlobalValue::getRealLinkageName(ParentF->getName()),
437 HT.CatchObjRecoverIdx);
438 FrameAllocOffsetRef = MCSymbolRefExpr::create(
439 FrameAllocOffset, MCSymbolRefExpr::VK_None, Asm->OutContext);
441 FrameAllocOffsetRef = MCConstantExpr::create(0, Asm->OutContext);
444 OS.EmitIntValue(HT.Adjectives, 4); // Adjectives
445 OS.EmitValue(create32bitRef(HT.TypeDescriptor), 4); // Type
446 OS.EmitValue(FrameAllocOffsetRef, 4); // CatchObjOffset
447 OS.EmitValue(create32bitRef(HT.Handler), 4); // Handler
449 if (shouldEmitPersonality) {
450 MCSymbol *ParentFrameOffset =
451 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(
452 GlobalValue::getRealLinkageName(HT.Handler->getName()));
453 const MCSymbolRefExpr *ParentFrameOffsetRef = MCSymbolRefExpr::create(
454 ParentFrameOffset, Asm->OutContext);
455 OS.EmitValue(ParentFrameOffsetRef, 4); // ParentFrameOffset
461 // IPToStateMapEntry {
465 if (IPToStateXData) {
466 OS.EmitLabel(IPToStateXData);
467 for (auto &IPStatePair : FuncInfo.IPToStateList) {
468 OS.EmitValue(create32bitRef(IPStatePair.first), 4); // IP
469 OS.EmitIntValue(IPStatePair.second, 4); // State
474 void WinException::extendIP2StateTable(const MachineFunction *MF,
475 const Function *ParentF,
476 WinEHFuncInfo &FuncInfo) {
477 const Function *F = MF->getFunction();
479 // The Itanium LSDA table sorts similar landing pads together to simplify the
480 // actions table, but we don't need that.
481 SmallVector<const LandingPadInfo *, 64> LandingPads;
482 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
483 LandingPads.reserve(PadInfos.size());
484 for (const auto &LP : PadInfos)
485 LandingPads.push_back(&LP);
488 computePadMap(LandingPads, PadMap);
490 // The end label of the previous invoke or nounwind try-range.
491 MCSymbol *LastLabel = Asm->getFunctionBegin();
493 // Whether there is a potentially throwing instruction (currently this means
494 // an ordinary call) between the end of the previous try-range and now.
495 bool SawPotentiallyThrowing = false;
497 int LastEHState = -2;
499 // The parent function and the catch handlers contribute to the 'ip2state'
502 // Include ip2state entries for the beginning of the main function and
503 // for catch handler functions.
505 FuncInfo.IPToStateList.push_back(std::make_pair(LastLabel, -1));
507 } else if (FuncInfo.HandlerBaseState.count(F)) {
508 FuncInfo.IPToStateList.push_back(
509 std::make_pair(LastLabel, FuncInfo.HandlerBaseState[F]));
510 LastEHState = FuncInfo.HandlerBaseState[F];
512 for (const auto &MBB : *MF) {
513 for (const auto &MI : MBB) {
514 if (!MI.isEHLabel()) {
516 SawPotentiallyThrowing |= !callToNoUnwindFunction(&MI);
520 // End of the previous try-range?
521 MCSymbol *BeginLabel = MI.getOperand(0).getMCSymbol();
522 if (BeginLabel == LastLabel)
523 SawPotentiallyThrowing = false;
525 // Beginning of a new try-range?
526 RangeMapType::const_iterator L = PadMap.find(BeginLabel);
527 if (L == PadMap.end())
528 // Nope, it was just some random label.
531 const PadRange &P = L->second;
532 const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
533 assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
534 "Inconsistent landing pad map!");
536 // FIXME: Should this be using FuncInfo.HandlerBaseState?
537 if (SawPotentiallyThrowing && LastEHState != -1) {
538 FuncInfo.IPToStateList.push_back(std::make_pair(LastLabel, -1));
539 SawPotentiallyThrowing = false;
543 if (LandingPad->WinEHState != LastEHState)
544 FuncInfo.IPToStateList.push_back(
545 std::make_pair(BeginLabel, LandingPad->WinEHState));
546 LastEHState = LandingPad->WinEHState;
547 LastLabel = LandingPad->EndLabels[P.RangeIndex];
552 void WinException::emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo,
553 StringRef FLinkageName) {
554 // Outlined helpers called by the EH runtime need to know the offset of the EH
555 // registration in order to recover the parent frame pointer. Now that we know
556 // we've code generated the parent, we can emit the label assignment that
557 // those helpers use to get the offset of the registration node.
558 assert(FuncInfo.EHRegNodeEscapeIndex != INT_MAX &&
559 "no EH reg node localescape index");
560 MCSymbol *ParentFrameOffset =
561 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(FLinkageName);
562 MCSymbol *RegistrationOffsetSym = Asm->OutContext.getOrCreateFrameAllocSymbol(
563 FLinkageName, FuncInfo.EHRegNodeEscapeIndex);
564 const MCExpr *RegistrationOffsetSymRef =
565 MCSymbolRefExpr::create(RegistrationOffsetSym, Asm->OutContext);
566 Asm->OutStreamer->EmitAssignment(ParentFrameOffset, RegistrationOffsetSymRef);
569 /// Emit the language-specific data that _except_handler3 and 4 expect. This is
570 /// functionally equivalent to the __C_specific_handler table, except it is
571 /// indexed by state number instead of IP.
572 void WinException::emitExceptHandlerTable(const MachineFunction *MF) {
573 MCStreamer &OS = *Asm->OutStreamer;
574 const Function *F = MF->getFunction();
575 StringRef FLinkageName = GlobalValue::getRealLinkageName(F->getName());
577 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
578 emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
580 // Emit the __ehtable label that we use for llvm.x86.seh.lsda.
581 MCSymbol *LSDALabel = Asm->OutContext.getOrCreateLSDASymbol(FLinkageName);
582 OS.EmitValueToAlignment(4);
583 OS.EmitLabel(LSDALabel);
585 const Function *Per = MMI->getPersonality();
586 StringRef PerName = Per->getName();
588 if (PerName == "_except_handler4") {
589 // The LSDA for _except_handler4 starts with this struct, followed by the
592 // struct EH4ScopeTable {
593 // int32_t GSCookieOffset;
594 // int32_t GSCookieXOROffset;
595 // int32_t EHCookieOffset;
596 // int32_t EHCookieXOROffset;
597 // ScopeTableEntry ScopeRecord[];
600 // Only the EHCookieOffset field appears to vary, and it appears to be the
601 // offset from the final saved SP value to the retaddr.
602 OS.EmitIntValue(-2, 4);
603 OS.EmitIntValue(0, 4);
605 OS.EmitIntValue(9999, 4);
606 OS.EmitIntValue(0, 4);
610 // Build a list of pointers to LandingPadInfos and then sort by WinEHState.
611 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
612 SmallVector<const LandingPadInfo *, 4> LPads;
613 LPads.reserve((PadInfos.size()));
614 for (const LandingPadInfo &LPInfo : PadInfos)
615 LPads.push_back(&LPInfo);
616 std::sort(LPads.begin(), LPads.end(),
617 [](const LandingPadInfo *L, const LandingPadInfo *R) {
618 return L->WinEHState < R->WinEHState;
621 // For each action in each lpad, emit one of these:
622 // struct ScopeTableEntry {
623 // int32_t EnclosingLevel;
624 // int32_t (__cdecl *Filter)();
625 // void *HandlerOrFinally;
628 // The "outermost" action will use BaseState as its enclosing level. Each
629 // other action will refer to the previous state as its enclosing level.
631 for (const LandingPadInfo *LPInfo : LPads) {
632 int EnclosingLevel = BaseState;
633 assert(CurState + int(LPInfo->SEHHandlers.size()) - 1 ==
634 LPInfo->WinEHState &&
635 "gaps in the SEH scope table");
636 for (auto I = LPInfo->SEHHandlers.rbegin(), E = LPInfo->SEHHandlers.rend();
638 const SEHHandler &Handler = *I;
639 const BlockAddress *BA = Handler.RecoverBA;
640 const Function *F = Handler.FilterOrFinally;
641 assert(F && "cannot catch all in 32-bit SEH without filter function");
642 const MCExpr *FilterOrNull =
643 create32bitRef(BA ? Asm->getSymbol(F) : nullptr);
644 const MCExpr *ExceptOrFinally = create32bitRef(
645 BA ? Asm->GetBlockAddressSymbol(BA) : Asm->getSymbol(F));
647 OS.EmitIntValue(EnclosingLevel, 4);
648 OS.EmitValue(FilterOrNull, 4);
649 OS.EmitValue(ExceptOrFinally, 4);
651 // The next state unwinds to this state.
652 EnclosingLevel = CurState;