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();
65 bool hasEHFunclets = MMI->hasEHFunclets();
67 const Function *F = MF->getFunction();
68 const Function *ParentF = MMI->getWinEHParent(F);
70 shouldEmitMoves = Asm->needsSEHMoves();
72 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
73 unsigned PerEncoding = TLOF.getPersonalityEncoding();
74 const Function *Per = nullptr;
75 if (F->hasPersonalityFn())
76 Per = dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
78 bool forceEmitPersonality =
79 F->hasPersonalityFn() && !isNoOpWithoutInvoke(classifyEHPersonality(Per)) &&
80 F->needsUnwindTableEntry();
82 shouldEmitPersonality =
83 forceEmitPersonality || ((hasLandingPads || hasEHFunclets) &&
84 PerEncoding != dwarf::DW_EH_PE_omit && Per);
86 unsigned LSDAEncoding = TLOF.getLSDAEncoding();
87 shouldEmitLSDA = shouldEmitPersonality &&
88 LSDAEncoding != dwarf::DW_EH_PE_omit;
90 // If we're not using CFI, we don't want the CFI or the personality, but we
91 // might want EH tables if we had EH pads.
92 // FIXME: If WinEHPrepare outlined something, we should emit the LSDA. Remove
93 // this once WinEHPrepare stops doing that.
94 if (!Asm->MAI->usesWindowsCFI()) {
96 hasEHFunclets || (F->hasFnAttribute("wineh-parent") && F == ParentF);
97 shouldEmitPersonality = false;
101 // If this was an outlined handler, we need to define the label corresponding
102 // to the offset of the parent frame relative to the stack pointer after the
105 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(ParentF);
106 auto I = FuncInfo.CatchHandlerParentFrameObjOffset.find(F);
107 if (I != FuncInfo.CatchHandlerParentFrameObjOffset.end()) {
108 MCSymbol *HandlerTypeParentFrameOffset =
109 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(
110 GlobalValue::getRealLinkageName(F->getName()));
112 // Emit a symbol assignment.
113 Asm->OutStreamer->EmitAssignment(
114 HandlerTypeParentFrameOffset,
115 MCConstantExpr::create(I->second, Asm->OutContext));
119 if (shouldEmitMoves || shouldEmitPersonality)
120 Asm->OutStreamer->EmitWinCFIStartProc(Asm->CurrentFnSym);
122 if (shouldEmitPersonality) {
123 const MCSymbol *PersHandlerSym =
124 TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
125 Asm->OutStreamer->EmitWinEHHandler(PersHandlerSym, true, true);
129 /// endFunction - Gather and emit post-function exception information.
131 void WinException::endFunction(const MachineFunction *MF) {
132 if (!shouldEmitPersonality && !shouldEmitMoves && !shouldEmitLSDA)
135 const Function *F = MF->getFunction();
136 EHPersonality Per = EHPersonality::Unknown;
137 if (F->hasPersonalityFn())
138 Per = classifyEHPersonality(F->getPersonalityFn());
140 // Get rid of any dead landing pads if we're not using a Windows EH scheme. In
141 // Windows EH schemes, the landing pad is not actually reachable. It only
142 // exists so that we can emit the right table data.
143 if (!isMSVCEHPersonality(Per))
144 MMI->TidyLandingPads();
146 if (shouldEmitPersonality || shouldEmitLSDA) {
147 Asm->OutStreamer->PushSection();
149 if (shouldEmitMoves || shouldEmitPersonality) {
150 // Emit an UNWIND_INFO struct describing the prologue.
151 Asm->OutStreamer->EmitWinEHHandlerData();
153 // Just switch sections to the right xdata section. This use of
154 // CurrentFnSym assumes that we only emit the LSDA when ending the parent
156 MCSection *XData = WinEH::UnwindEmitter::getXDataSection(
157 Asm->CurrentFnSym, Asm->OutContext);
158 Asm->OutStreamer->SwitchSection(XData);
161 // Emit the tables appropriate to the personality function in use. If we
162 // don't recognize the personality, assume it uses an Itanium-style LSDA.
163 if (Per == EHPersonality::MSVC_Win64SEH)
164 emitCSpecificHandlerTable();
165 else if (Per == EHPersonality::MSVC_X86SEH)
166 emitExceptHandlerTable(MF);
167 else if (Per == EHPersonality::MSVC_CXX)
168 emitCXXFrameHandler3Table(MF);
170 emitExceptionTable();
172 Asm->OutStreamer->PopSection();
176 Asm->OutStreamer->EmitWinCFIEndProc();
179 const MCExpr *WinException::create32bitRef(const MCSymbol *Value) {
181 return MCConstantExpr::create(0, Asm->OutContext);
182 return MCSymbolRefExpr::create(Value, useImageRel32
183 ? MCSymbolRefExpr::VK_COFF_IMGREL32
184 : MCSymbolRefExpr::VK_None,
188 const MCExpr *WinException::create32bitRef(const Value *V) {
190 return MCConstantExpr::create(0, Asm->OutContext);
191 // FIXME: Delete the GlobalValue case once the new IR is fully functional.
192 if (const auto *GV = dyn_cast<GlobalValue>(V))
193 return create32bitRef(Asm->getSymbol(GV));
194 return create32bitRef(MMI->getAddrLabelSymbol(cast<BasicBlock>(V)));
197 /// Emit the language-specific data that __C_specific_handler expects. This
198 /// handler lives in the x64 Microsoft C runtime and allows catching or cleaning
199 /// up after faults with __try, __except, and __finally. The typeinfo values
200 /// are not really RTTI data, but pointers to filter functions that return an
201 /// integer (1, 0, or -1) indicating how to handle the exception. For __finally
202 /// blocks and other cleanups, the landing pad label is zero, and the filter
203 /// function is actually a cleanup handler with the same prototype. A catch-all
204 /// entry is modeled with a null filter function field and a non-zero landing
207 /// Possible filter function return values:
208 /// EXCEPTION_EXECUTE_HANDLER (1):
209 /// Jump to the landing pad label after cleanups.
210 /// EXCEPTION_CONTINUE_SEARCH (0):
211 /// Continue searching this table or continue unwinding.
212 /// EXCEPTION_CONTINUE_EXECUTION (-1):
213 /// Resume execution at the trapping PC.
215 /// Inferred table structure:
219 /// imagerel32 LabelStart;
220 /// imagerel32 LabelEnd;
221 /// imagerel32 FilterOrFinally; // One means catch-all.
222 /// imagerel32 LabelLPad; // Zero means __finally.
223 /// } Entries[NumEntries];
225 void WinException::emitCSpecificHandlerTable() {
226 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
228 // Simplifying assumptions for first implementation:
229 // - Cleanups are not implemented.
230 // - Filters are not implemented.
232 // The Itanium LSDA table sorts similar landing pads together to simplify the
233 // actions table, but we don't need that.
234 SmallVector<const LandingPadInfo *, 64> LandingPads;
235 LandingPads.reserve(PadInfos.size());
236 for (const auto &LP : PadInfos)
237 LandingPads.push_back(&LP);
239 // Compute label ranges for call sites as we would for the Itanium LSDA, but
240 // use an all zero action table because we aren't using these actions.
241 SmallVector<unsigned, 64> FirstActions;
242 FirstActions.resize(LandingPads.size());
243 SmallVector<CallSiteEntry, 64> CallSites;
244 computeCallSiteTable(CallSites, LandingPads, FirstActions);
246 MCSymbol *EHFuncBeginSym = Asm->getFunctionBegin();
247 MCSymbol *EHFuncEndSym = Asm->getFunctionEnd();
249 // Emit the number of table entries.
250 unsigned NumEntries = 0;
251 for (const CallSiteEntry &CSE : CallSites) {
253 continue; // Ignore gaps.
254 NumEntries += CSE.LPad->SEHHandlers.size();
256 Asm->OutStreamer->EmitIntValue(NumEntries, 4);
258 // If there are no actions, we don't need to iterate again.
262 // Emit the four-label records for each call site entry. The table has to be
263 // sorted in layout order, and the call sites should already be sorted.
264 for (const CallSiteEntry &CSE : CallSites) {
265 // Ignore gaps. Unlike the Itanium model, unwinding through a frame without
266 // an EH table entry will propagate the exception rather than terminating
270 const LandingPadInfo *LPad = CSE.LPad;
272 // Compute the label range. We may reuse the function begin and end labels
273 // rather than forming new ones.
274 const MCExpr *Begin =
275 create32bitRef(CSE.BeginLabel ? CSE.BeginLabel : EHFuncBeginSym);
278 // The interval is half-open, so we have to add one to include the return
279 // address of the last invoke in the range.
280 End = MCBinaryExpr::createAdd(create32bitRef(CSE.EndLabel),
281 MCConstantExpr::create(1, Asm->OutContext),
284 End = create32bitRef(EHFuncEndSym);
287 // Emit an entry for each action.
288 for (SEHHandler Handler : LPad->SEHHandlers) {
289 Asm->OutStreamer->EmitValue(Begin, 4);
290 Asm->OutStreamer->EmitValue(End, 4);
292 // Emit the filter or finally function pointer, if present. Otherwise,
293 // emit '1' to indicate a catch-all.
294 const Function *F = Handler.FilterOrFinally;
296 Asm->OutStreamer->EmitValue(create32bitRef(Asm->getSymbol(F)), 4);
298 Asm->OutStreamer->EmitIntValue(1, 4);
300 // Emit the recovery address, if present. Otherwise, this must be a
302 const BlockAddress *BA = Handler.RecoverBA;
304 Asm->OutStreamer->EmitValue(
305 create32bitRef(Asm->GetBlockAddressSymbol(BA)), 4);
307 Asm->OutStreamer->EmitIntValue(0, 4);
312 void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
313 const Function *F = MF->getFunction();
314 const Function *ParentF = MMI->getWinEHParent(F);
315 auto &OS = *Asm->OutStreamer;
316 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(ParentF);
318 StringRef ParentLinkageName =
319 GlobalValue::getRealLinkageName(ParentF->getName());
321 MCSymbol *FuncInfoXData = nullptr;
322 if (shouldEmitPersonality) {
323 FuncInfoXData = Asm->OutContext.getOrCreateSymbol(
324 Twine("$cppxdata$", ParentLinkageName));
325 OS.EmitValue(create32bitRef(FuncInfoXData), 4);
327 extendIP2StateTable(MF, ParentF, FuncInfo);
329 if (!MMI->hasEHFunclets()) {
330 // Defer emission until we've visited the parent function and all the
331 // catch handlers. Cleanups don't contribute to the ip2state table, so
333 if (ParentF != F && !FuncInfo.CatchHandlerMaxState.count(F))
335 ++FuncInfo.NumIPToStateFuncsVisited;
336 if (FuncInfo.NumIPToStateFuncsVisited !=
337 FuncInfo.CatchHandlerMaxState.size())
341 FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(ParentLinkageName);
342 emitEHRegistrationOffsetLabel(FuncInfo, ParentLinkageName);
345 MCSymbol *UnwindMapXData = nullptr;
346 MCSymbol *TryBlockMapXData = nullptr;
347 MCSymbol *IPToStateXData = nullptr;
348 if (!FuncInfo.UnwindMap.empty())
349 UnwindMapXData = Asm->OutContext.getOrCreateSymbol(
350 Twine("$stateUnwindMap$", ParentLinkageName));
351 if (!FuncInfo.TryBlockMap.empty())
352 TryBlockMapXData = Asm->OutContext.getOrCreateSymbol(
353 Twine("$tryMap$", ParentLinkageName));
354 if (!FuncInfo.IPToStateList.empty())
355 IPToStateXData = Asm->OutContext.getOrCreateSymbol(
356 Twine("$ip2state$", ParentLinkageName));
359 // uint32_t MagicNumber
361 // UnwindMapEntry *UnwindMap;
362 // uint32_t NumTryBlocks;
363 // TryBlockMapEntry *TryBlockMap;
364 // uint32_t IPMapEntries; // always 0 for x86
365 // IPToStateMapEntry *IPToStateMap; // always 0 for x86
366 // uint32_t UnwindHelp; // non-x86 only
367 // ESTypeList *ESTypeList;
370 // EHFlags & 1 -> Synchronous exceptions only, no async exceptions.
371 // EHFlags & 2 -> ???
372 // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue.
373 OS.EmitValueToAlignment(4);
374 OS.EmitLabel(FuncInfoXData);
375 OS.EmitIntValue(0x19930522, 4); // MagicNumber
376 OS.EmitIntValue(FuncInfo.UnwindMap.size(), 4); // MaxState
377 OS.EmitValue(create32bitRef(UnwindMapXData), 4); // UnwindMap
378 OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4); // NumTryBlocks
379 OS.EmitValue(create32bitRef(TryBlockMapXData), 4); // TryBlockMap
380 OS.EmitIntValue(FuncInfo.IPToStateList.size(), 4); // IPMapEntries
381 OS.EmitValue(create32bitRef(IPToStateXData), 4); // IPToStateMap
382 if (Asm->MAI->usesWindowsCFI())
383 OS.EmitIntValue(FuncInfo.UnwindHelpFrameOffset, 4); // UnwindHelp
384 OS.EmitIntValue(0, 4); // ESTypeList
385 OS.EmitIntValue(1, 4); // EHFlags
391 if (UnwindMapXData) {
392 OS.EmitLabel(UnwindMapXData);
393 for (const WinEHUnwindMapEntry &UME : FuncInfo.UnwindMap) {
394 OS.EmitIntValue(UME.ToState, 4); // ToState
395 OS.EmitValue(create32bitRef(UME.Cleanup), 4); // Action
402 // int32_t CatchHigh;
403 // int32_t NumCatches;
404 // HandlerType *HandlerArray;
406 if (TryBlockMapXData) {
407 OS.EmitLabel(TryBlockMapXData);
408 SmallVector<MCSymbol *, 1> HandlerMaps;
409 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
410 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
411 MCSymbol *HandlerMapXData = nullptr;
413 if (!TBME.HandlerArray.empty())
415 Asm->OutContext.getOrCreateSymbol(Twine("$handlerMap$")
418 .concat(ParentLinkageName));
420 HandlerMaps.push_back(HandlerMapXData);
422 int CatchHigh = TBME.CatchHigh;
423 if (CatchHigh == -1) {
424 for (WinEHHandlerType &HT : TBME.HandlerArray)
425 CatchHigh = std::max(
427 FuncInfo.CatchHandlerMaxState[cast<Function>(HT.Handler)]);
430 assert(TBME.TryLow <= TBME.TryHigh);
431 OS.EmitIntValue(TBME.TryLow, 4); // TryLow
432 OS.EmitIntValue(TBME.TryHigh, 4); // TryHigh
433 OS.EmitIntValue(CatchHigh, 4); // CatchHigh
434 OS.EmitIntValue(TBME.HandlerArray.size(), 4); // NumCatches
435 OS.EmitValue(create32bitRef(HandlerMapXData), 4); // HandlerArray
438 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
439 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
440 MCSymbol *HandlerMapXData = HandlerMaps[I];
441 if (!HandlerMapXData)
444 // int32_t Adjectives;
445 // TypeDescriptor *Type;
446 // int32_t CatchObjOffset;
447 // void (*Handler)();
448 // int32_t ParentFrameOffset; // x64 only
450 OS.EmitLabel(HandlerMapXData);
451 for (const WinEHHandlerType &HT : TBME.HandlerArray) {
452 // Get the frame escape label with the offset of the catch object. If
453 // the index is -1, then there is no catch object, and we should emit an
454 // offset of zero, indicating that no copy will occur.
455 const MCExpr *FrameAllocOffsetRef = nullptr;
456 if (HT.CatchObjRecoverIdx >= 0) {
457 MCSymbol *FrameAllocOffset =
458 Asm->OutContext.getOrCreateFrameAllocSymbol(
459 GlobalValue::getRealLinkageName(ParentF->getName()),
460 HT.CatchObjRecoverIdx);
461 FrameAllocOffsetRef = MCSymbolRefExpr::create(
462 FrameAllocOffset, MCSymbolRefExpr::VK_None, Asm->OutContext);
464 FrameAllocOffsetRef = MCConstantExpr::create(0, Asm->OutContext);
467 OS.EmitIntValue(HT.Adjectives, 4); // Adjectives
468 OS.EmitValue(create32bitRef(HT.TypeDescriptor), 4); // Type
469 OS.EmitValue(FrameAllocOffsetRef, 4); // CatchObjOffset
470 if (HT.HandlerMBB) // Handler
471 OS.EmitValue(create32bitRef(HT.HandlerMBB->getSymbol()), 4);
473 OS.EmitValue(create32bitRef(HT.Handler), 4);
475 if (shouldEmitPersonality) {
476 if (FuncInfo.CatchHandlerParentFrameObjOffset.empty()) {
477 // With the new IR, this is always 16 + 8 + getMaxCallFrameSize().
478 // Keep this in sync with X86FrameLowering::emitPrologue.
479 int ParentFrameOffset =
480 16 + 8 + MF->getFrameInfo()->getMaxCallFrameSize();
481 OS.EmitIntValue(ParentFrameOffset, 4); // ParentFrameOffset
483 MCSymbol *ParentFrameOffset =
484 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(
485 GlobalValue::getRealLinkageName(HT.Handler->getName()));
486 const MCSymbolRefExpr *ParentFrameOffsetRef =
487 MCSymbolRefExpr::create(ParentFrameOffset, Asm->OutContext);
488 OS.EmitValue(ParentFrameOffsetRef, 4); // ParentFrameOffset
495 // IPToStateMapEntry {
499 if (IPToStateXData) {
500 OS.EmitLabel(IPToStateXData);
501 for (auto &IPStatePair : FuncInfo.IPToStateList) {
502 OS.EmitValue(create32bitRef(IPStatePair.first), 4); // IP
503 OS.EmitIntValue(IPStatePair.second, 4); // State
508 void WinException::extendIP2StateTable(const MachineFunction *MF,
509 const Function *ParentF,
510 WinEHFuncInfo &FuncInfo) {
511 const Function *F = MF->getFunction();
513 // The Itanium LSDA table sorts similar landing pads together to simplify the
514 // actions table, but we don't need that.
515 SmallVector<const LandingPadInfo *, 64> LandingPads;
516 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
517 LandingPads.reserve(PadInfos.size());
518 for (const auto &LP : PadInfos)
519 LandingPads.push_back(&LP);
522 computePadMap(LandingPads, PadMap);
524 // The end label of the previous invoke or nounwind try-range.
525 MCSymbol *LastLabel = Asm->getFunctionBegin();
527 // Whether there is a potentially throwing instruction (currently this means
528 // an ordinary call) between the end of the previous try-range and now.
529 bool SawPotentiallyThrowing = false;
531 int LastEHState = -2;
533 // The parent function and the catch handlers contribute to the 'ip2state'
536 // Include ip2state entries for the beginning of the main function and
537 // for catch handler functions.
539 FuncInfo.IPToStateList.push_back(std::make_pair(LastLabel, -1));
541 } else if (FuncInfo.HandlerBaseState.count(F)) {
542 FuncInfo.IPToStateList.push_back(
543 std::make_pair(LastLabel, FuncInfo.HandlerBaseState[F]));
544 LastEHState = FuncInfo.HandlerBaseState[F];
546 for (const auto &MBB : *MF) {
547 for (const auto &MI : MBB) {
548 if (!MI.isEHLabel()) {
550 SawPotentiallyThrowing |= !callToNoUnwindFunction(&MI);
554 // End of the previous try-range?
555 MCSymbol *BeginLabel = MI.getOperand(0).getMCSymbol();
556 if (BeginLabel == LastLabel)
557 SawPotentiallyThrowing = false;
559 // Beginning of a new try-range?
560 RangeMapType::const_iterator L = PadMap.find(BeginLabel);
561 if (L == PadMap.end())
562 // Nope, it was just some random label.
565 const PadRange &P = L->second;
566 const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
567 assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
568 "Inconsistent landing pad map!");
570 // FIXME: Should this be using FuncInfo.HandlerBaseState?
571 if (SawPotentiallyThrowing && LastEHState != -1) {
572 FuncInfo.IPToStateList.push_back(std::make_pair(LastLabel, -1));
573 SawPotentiallyThrowing = false;
577 if (LandingPad->WinEHState != LastEHState)
578 FuncInfo.IPToStateList.push_back(
579 std::make_pair(BeginLabel, LandingPad->WinEHState));
580 LastEHState = LandingPad->WinEHState;
581 LastLabel = LandingPad->EndLabels[P.RangeIndex];
586 void WinException::emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo,
587 StringRef FLinkageName) {
588 // Outlined helpers called by the EH runtime need to know the offset of the EH
589 // registration in order to recover the parent frame pointer. Now that we know
590 // we've code generated the parent, we can emit the label assignment that
591 // those helpers use to get the offset of the registration node.
592 assert(FuncInfo.EHRegNodeEscapeIndex != INT_MAX &&
593 "no EH reg node localescape index");
594 MCSymbol *ParentFrameOffset =
595 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(FLinkageName);
596 MCSymbol *RegistrationOffsetSym = Asm->OutContext.getOrCreateFrameAllocSymbol(
597 FLinkageName, FuncInfo.EHRegNodeEscapeIndex);
598 const MCExpr *RegistrationOffsetSymRef =
599 MCSymbolRefExpr::create(RegistrationOffsetSym, Asm->OutContext);
600 Asm->OutStreamer->EmitAssignment(ParentFrameOffset, RegistrationOffsetSymRef);
603 /// Emit the language-specific data that _except_handler3 and 4 expect. This is
604 /// functionally equivalent to the __C_specific_handler table, except it is
605 /// indexed by state number instead of IP.
606 void WinException::emitExceptHandlerTable(const MachineFunction *MF) {
607 MCStreamer &OS = *Asm->OutStreamer;
608 const Function *F = MF->getFunction();
609 StringRef FLinkageName = GlobalValue::getRealLinkageName(F->getName());
611 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
612 emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
614 // Emit the __ehtable label that we use for llvm.x86.seh.lsda.
615 MCSymbol *LSDALabel = Asm->OutContext.getOrCreateLSDASymbol(FLinkageName);
616 OS.EmitValueToAlignment(4);
617 OS.EmitLabel(LSDALabel);
619 const Function *Per =
620 dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
621 StringRef PerName = Per->getName();
623 if (PerName == "_except_handler4") {
624 // The LSDA for _except_handler4 starts with this struct, followed by the
627 // struct EH4ScopeTable {
628 // int32_t GSCookieOffset;
629 // int32_t GSCookieXOROffset;
630 // int32_t EHCookieOffset;
631 // int32_t EHCookieXOROffset;
632 // ScopeTableEntry ScopeRecord[];
635 // Only the EHCookieOffset field appears to vary, and it appears to be the
636 // offset from the final saved SP value to the retaddr.
637 OS.EmitIntValue(-2, 4);
638 OS.EmitIntValue(0, 4);
640 OS.EmitIntValue(9999, 4);
641 OS.EmitIntValue(0, 4);
645 // Build a list of pointers to LandingPadInfos and then sort by WinEHState.
646 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
647 SmallVector<const LandingPadInfo *, 4> LPads;
648 LPads.reserve((PadInfos.size()));
649 for (const LandingPadInfo &LPInfo : PadInfos)
650 LPads.push_back(&LPInfo);
651 std::sort(LPads.begin(), LPads.end(),
652 [](const LandingPadInfo *L, const LandingPadInfo *R) {
653 return L->WinEHState < R->WinEHState;
656 // For each action in each lpad, emit one of these:
657 // struct ScopeTableEntry {
658 // int32_t EnclosingLevel;
659 // int32_t (__cdecl *Filter)();
660 // void *HandlerOrFinally;
663 // The "outermost" action will use BaseState as its enclosing level. Each
664 // other action will refer to the previous state as its enclosing level.
666 for (const LandingPadInfo *LPInfo : LPads) {
667 int EnclosingLevel = BaseState;
668 assert(CurState + int(LPInfo->SEHHandlers.size()) - 1 ==
669 LPInfo->WinEHState &&
670 "gaps in the SEH scope table");
671 for (auto I = LPInfo->SEHHandlers.rbegin(), E = LPInfo->SEHHandlers.rend();
673 const SEHHandler &Handler = *I;
674 const BlockAddress *BA = Handler.RecoverBA;
675 const Function *F = Handler.FilterOrFinally;
676 assert(F && "cannot catch all in 32-bit SEH without filter function");
677 const MCExpr *FilterOrNull =
678 create32bitRef(BA ? Asm->getSymbol(F) : nullptr);
679 const MCExpr *ExceptOrFinally = create32bitRef(
680 BA ? Asm->GetBlockAddressSymbol(BA) : Asm->getSymbol(F));
682 OS.EmitIntValue(EnclosingLevel, 4);
683 OS.EmitValue(FilterOrNull, 4);
684 OS.EmitValue(ExceptOrFinally, 4);
686 // The next state unwinds to this state.
687 EnclosingLevel = CurState;