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 (shouldEmitMoves || shouldEmitPersonality)
102 Asm->OutStreamer->EmitWinCFIStartProc(Asm->CurrentFnSym);
104 if (shouldEmitPersonality) {
105 const MCSymbol *PersHandlerSym =
106 TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
107 Asm->OutStreamer->EmitWinEHHandler(PersHandlerSym, true, true);
111 /// endFunction - Gather and emit post-function exception information.
113 void WinException::endFunction(const MachineFunction *MF) {
114 if (!shouldEmitPersonality && !shouldEmitMoves && !shouldEmitLSDA)
117 const Function *F = MF->getFunction();
118 EHPersonality Per = EHPersonality::Unknown;
119 if (F->hasPersonalityFn())
120 Per = classifyEHPersonality(F->getPersonalityFn());
122 // Get rid of any dead landing pads if we're not using a Windows EH scheme. In
123 // Windows EH schemes, the landing pad is not actually reachable. It only
124 // exists so that we can emit the right table data.
125 if (!isMSVCEHPersonality(Per))
126 MMI->TidyLandingPads();
128 if (shouldEmitPersonality || shouldEmitLSDA) {
129 Asm->OutStreamer->PushSection();
131 if (shouldEmitMoves || shouldEmitPersonality) {
132 // Emit an UNWIND_INFO struct describing the prologue.
133 Asm->OutStreamer->EmitWinEHHandlerData();
135 // Just switch sections to the right xdata section. This use of
136 // CurrentFnSym assumes that we only emit the LSDA when ending the parent
138 MCSection *XData = WinEH::UnwindEmitter::getXDataSection(
139 Asm->CurrentFnSym, Asm->OutContext);
140 Asm->OutStreamer->SwitchSection(XData);
143 // Emit the tables appropriate to the personality function in use. If we
144 // don't recognize the personality, assume it uses an Itanium-style LSDA.
145 if (Per == EHPersonality::MSVC_Win64SEH)
146 emitCSpecificHandlerTable(MF);
147 else if (Per == EHPersonality::MSVC_X86SEH)
148 emitExceptHandlerTable(MF);
149 else if (Per == EHPersonality::MSVC_CXX)
150 emitCXXFrameHandler3Table(MF);
152 emitExceptionTable();
154 Asm->OutStreamer->PopSection();
157 if (shouldEmitMoves || shouldEmitPersonality)
158 Asm->OutStreamer->EmitWinCFIEndProc();
161 const MCExpr *WinException::create32bitRef(const MCSymbol *Value) {
163 return MCConstantExpr::create(0, Asm->OutContext);
164 return MCSymbolRefExpr::create(Value, useImageRel32
165 ? MCSymbolRefExpr::VK_COFF_IMGREL32
166 : MCSymbolRefExpr::VK_None,
170 const MCExpr *WinException::create32bitRef(const Value *V) {
172 return MCConstantExpr::create(0, Asm->OutContext);
173 // FIXME: Delete the GlobalValue case once the new IR is fully functional.
174 if (const auto *GV = dyn_cast<GlobalValue>(V))
175 return create32bitRef(Asm->getSymbol(GV));
176 return create32bitRef(MMI->getAddrLabelSymbol(cast<BasicBlock>(V)));
179 const MCExpr *WinException::getLabelPlusOne(MCSymbol *Label) {
180 return MCBinaryExpr::createAdd(create32bitRef(Label),
181 MCConstantExpr::create(1, Asm->OutContext),
185 /// Emit the language-specific data that __C_specific_handler expects. This
186 /// handler lives in the x64 Microsoft C runtime and allows catching or cleaning
187 /// up after faults with __try, __except, and __finally. The typeinfo values
188 /// are not really RTTI data, but pointers to filter functions that return an
189 /// integer (1, 0, or -1) indicating how to handle the exception. For __finally
190 /// blocks and other cleanups, the landing pad label is zero, and the filter
191 /// function is actually a cleanup handler with the same prototype. A catch-all
192 /// entry is modeled with a null filter function field and a non-zero landing
195 /// Possible filter function return values:
196 /// EXCEPTION_EXECUTE_HANDLER (1):
197 /// Jump to the landing pad label after cleanups.
198 /// EXCEPTION_CONTINUE_SEARCH (0):
199 /// Continue searching this table or continue unwinding.
200 /// EXCEPTION_CONTINUE_EXECUTION (-1):
201 /// Resume execution at the trapping PC.
203 /// Inferred table structure:
207 /// imagerel32 LabelStart;
208 /// imagerel32 LabelEnd;
209 /// imagerel32 FilterOrFinally; // One means catch-all.
210 /// imagerel32 LabelLPad; // Zero means __finally.
211 /// } Entries[NumEntries];
213 void WinException::emitCSpecificHandlerTable(const MachineFunction *MF) {
214 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
216 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(MF->getFunction());
217 if (!FuncInfo.SEHUnwindMap.empty())
218 report_fatal_error("x64 SEH tables not yet implemented");
220 // Simplifying assumptions for first implementation:
221 // - Cleanups are not implemented.
222 // - Filters are not implemented.
224 // The Itanium LSDA table sorts similar landing pads together to simplify the
225 // actions table, but we don't need that.
226 SmallVector<const LandingPadInfo *, 64> LandingPads;
227 LandingPads.reserve(PadInfos.size());
228 for (const auto &LP : PadInfos)
229 LandingPads.push_back(&LP);
231 // Compute label ranges for call sites as we would for the Itanium LSDA, but
232 // use an all zero action table because we aren't using these actions.
233 SmallVector<unsigned, 64> FirstActions;
234 FirstActions.resize(LandingPads.size());
235 SmallVector<CallSiteEntry, 64> CallSites;
236 computeCallSiteTable(CallSites, LandingPads, FirstActions);
238 MCSymbol *EHFuncBeginSym = Asm->getFunctionBegin();
239 MCSymbol *EHFuncEndSym = Asm->getFunctionEnd();
241 // Emit the number of table entries.
242 unsigned NumEntries = 0;
243 for (const CallSiteEntry &CSE : CallSites) {
245 continue; // Ignore gaps.
246 NumEntries += CSE.LPad->SEHHandlers.size();
248 Asm->OutStreamer->EmitIntValue(NumEntries, 4);
250 // If there are no actions, we don't need to iterate again.
254 // Emit the four-label records for each call site entry. The table has to be
255 // sorted in layout order, and the call sites should already be sorted.
256 for (const CallSiteEntry &CSE : CallSites) {
257 // Ignore gaps. Unlike the Itanium model, unwinding through a frame without
258 // an EH table entry will propagate the exception rather than terminating
262 const LandingPadInfo *LPad = CSE.LPad;
264 // Compute the label range. We may reuse the function begin and end labels
265 // rather than forming new ones.
266 const MCExpr *Begin =
267 create32bitRef(CSE.BeginLabel ? CSE.BeginLabel : EHFuncBeginSym);
270 // The interval is half-open, so we have to add one to include the return
271 // address of the last invoke in the range.
272 End = getLabelPlusOne(CSE.EndLabel);
274 End = create32bitRef(EHFuncEndSym);
277 // Emit an entry for each action.
278 for (SEHHandler Handler : LPad->SEHHandlers) {
279 Asm->OutStreamer->EmitValue(Begin, 4);
280 Asm->OutStreamer->EmitValue(End, 4);
282 // Emit the filter or finally function pointer, if present. Otherwise,
283 // emit '1' to indicate a catch-all.
284 const Function *F = Handler.FilterOrFinally;
286 Asm->OutStreamer->EmitValue(create32bitRef(Asm->getSymbol(F)), 4);
288 Asm->OutStreamer->EmitIntValue(1, 4);
290 // Emit the recovery address, if present. Otherwise, this must be a
292 const BlockAddress *BA = Handler.RecoverBA;
294 Asm->OutStreamer->EmitValue(
295 create32bitRef(Asm->GetBlockAddressSymbol(BA)), 4);
297 Asm->OutStreamer->EmitIntValue(0, 4);
302 /// Retreive the MCSymbol for a GlobalValue or MachineBasicBlock. GlobalValues
303 /// are used in the old WinEH scheme, and they will be removed eventually.
304 static MCSymbol *getMCSymbolForMBBOrGV(AsmPrinter *Asm, ValueOrMBB Handler) {
307 if (Handler.is<MachineBasicBlock *>())
308 return Handler.get<MachineBasicBlock *>()->getSymbol();
309 return Asm->getSymbol(cast<GlobalValue>(Handler.get<const Value *>()));
312 void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
313 const Function *F = MF->getFunction();
314 auto &OS = *Asm->OutStreamer;
315 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
317 StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
319 SmallVector<std::pair<const MCExpr *, int>, 4> IPToStateTable;
320 MCSymbol *FuncInfoXData = nullptr;
321 if (shouldEmitPersonality) {
322 // If we're 64-bit, emit a pointer to the C++ EH data, and build a map from
323 // IPs to state numbers.
325 Asm->OutContext.getOrCreateSymbol(Twine("$cppxdata$", FuncLinkageName));
326 OS.EmitValue(create32bitRef(FuncInfoXData), 4);
327 computeIP2StateTable(MF, FuncInfo, IPToStateTable);
329 FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(FuncLinkageName);
330 emitEHRegistrationOffsetLabel(FuncInfo, FuncLinkageName);
333 MCSymbol *UnwindMapXData = nullptr;
334 MCSymbol *TryBlockMapXData = nullptr;
335 MCSymbol *IPToStateXData = nullptr;
336 if (!FuncInfo.UnwindMap.empty())
337 UnwindMapXData = Asm->OutContext.getOrCreateSymbol(
338 Twine("$stateUnwindMap$", FuncLinkageName));
339 if (!FuncInfo.TryBlockMap.empty())
341 Asm->OutContext.getOrCreateSymbol(Twine("$tryMap$", FuncLinkageName));
342 if (!IPToStateTable.empty())
344 Asm->OutContext.getOrCreateSymbol(Twine("$ip2state$", FuncLinkageName));
347 // uint32_t MagicNumber
349 // UnwindMapEntry *UnwindMap;
350 // uint32_t NumTryBlocks;
351 // TryBlockMapEntry *TryBlockMap;
352 // uint32_t IPMapEntries; // always 0 for x86
353 // IPToStateMapEntry *IPToStateMap; // always 0 for x86
354 // uint32_t UnwindHelp; // non-x86 only
355 // ESTypeList *ESTypeList;
358 // EHFlags & 1 -> Synchronous exceptions only, no async exceptions.
359 // EHFlags & 2 -> ???
360 // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue.
361 OS.EmitValueToAlignment(4);
362 OS.EmitLabel(FuncInfoXData);
363 OS.EmitIntValue(0x19930522, 4); // MagicNumber
364 OS.EmitIntValue(FuncInfo.UnwindMap.size(), 4); // MaxState
365 OS.EmitValue(create32bitRef(UnwindMapXData), 4); // UnwindMap
366 OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4); // NumTryBlocks
367 OS.EmitValue(create32bitRef(TryBlockMapXData), 4); // TryBlockMap
368 OS.EmitIntValue(IPToStateTable.size(), 4); // IPMapEntries
369 OS.EmitValue(create32bitRef(IPToStateXData), 4); // IPToStateMap
370 if (Asm->MAI->usesWindowsCFI())
371 OS.EmitIntValue(FuncInfo.UnwindHelpFrameOffset, 4); // UnwindHelp
372 OS.EmitIntValue(0, 4); // ESTypeList
373 OS.EmitIntValue(1, 4); // EHFlags
379 if (UnwindMapXData) {
380 OS.EmitLabel(UnwindMapXData);
381 for (const WinEHUnwindMapEntry &UME : FuncInfo.UnwindMap) {
382 MCSymbol *CleanupSym = getMCSymbolForMBBOrGV(Asm, UME.Cleanup);
383 OS.EmitIntValue(UME.ToState, 4); // ToState
384 OS.EmitValue(create32bitRef(CleanupSym), 4); // Action
391 // int32_t CatchHigh;
392 // int32_t NumCatches;
393 // HandlerType *HandlerArray;
395 if (TryBlockMapXData) {
396 OS.EmitLabel(TryBlockMapXData);
397 SmallVector<MCSymbol *, 1> HandlerMaps;
398 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
399 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
401 MCSymbol *HandlerMapXData = nullptr;
402 if (!TBME.HandlerArray.empty())
404 Asm->OutContext.getOrCreateSymbol(Twine("$handlerMap$")
407 .concat(FuncLinkageName));
408 HandlerMaps.push_back(HandlerMapXData);
410 // TBMEs should form intervals.
411 assert(0 <= TBME.TryLow && "bad trymap interval");
412 assert(TBME.TryLow <= TBME.TryHigh && "bad trymap interval");
413 assert(TBME.TryHigh < TBME.CatchHigh && "bad trymap interval");
414 assert(TBME.CatchHigh < int(FuncInfo.UnwindMap.size()) &&
415 "bad trymap interval");
417 OS.EmitIntValue(TBME.TryLow, 4); // TryLow
418 OS.EmitIntValue(TBME.TryHigh, 4); // TryHigh
419 OS.EmitIntValue(TBME.CatchHigh, 4); // CatchHigh
420 OS.EmitIntValue(TBME.HandlerArray.size(), 4); // NumCatches
421 OS.EmitValue(create32bitRef(HandlerMapXData), 4); // HandlerArray
424 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
425 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
426 MCSymbol *HandlerMapXData = HandlerMaps[I];
427 if (!HandlerMapXData)
430 // int32_t Adjectives;
431 // TypeDescriptor *Type;
432 // int32_t CatchObjOffset;
433 // void (*Handler)();
434 // int32_t ParentFrameOffset; // x64 only
436 OS.EmitLabel(HandlerMapXData);
437 for (const WinEHHandlerType &HT : TBME.HandlerArray) {
438 // Get the frame escape label with the offset of the catch object. If
439 // the index is -1, then there is no catch object, and we should emit an
440 // offset of zero, indicating that no copy will occur.
441 const MCExpr *FrameAllocOffsetRef = nullptr;
442 if (HT.CatchObjRecoverIdx >= 0) {
443 MCSymbol *FrameAllocOffset =
444 Asm->OutContext.getOrCreateFrameAllocSymbol(
445 FuncLinkageName, HT.CatchObjRecoverIdx);
446 FrameAllocOffsetRef = MCSymbolRefExpr::create(
447 FrameAllocOffset, MCSymbolRefExpr::VK_None, Asm->OutContext);
448 } else if (HT.CatchObj.FrameOffset != INT_MAX) {
449 int Offset = HT.CatchObj.FrameOffset;
450 // For 32-bit, the catch object offset is relative to the end of the
451 // EH registration node. For 64-bit, it's relative to SP at the end of
453 if (!shouldEmitPersonality) {
454 assert(FuncInfo.EHRegNodeEndOffset != INT_MAX);
455 Offset += FuncInfo.EHRegNodeEndOffset;
457 FrameAllocOffsetRef = MCConstantExpr::create(Offset, Asm->OutContext);
459 FrameAllocOffsetRef = MCConstantExpr::create(0, Asm->OutContext);
462 MCSymbol *HandlerSym = getMCSymbolForMBBOrGV(Asm, HT.Handler);
464 OS.EmitIntValue(HT.Adjectives, 4); // Adjectives
465 OS.EmitValue(create32bitRef(HT.TypeDescriptor), 4); // Type
466 OS.EmitValue(FrameAllocOffsetRef, 4); // CatchObjOffset
467 OS.EmitValue(create32bitRef(HandlerSym), 4); // Handler
469 if (shouldEmitPersonality) {
470 // With the new IR, this is always 16 + 8 + getMaxCallFrameSize().
471 // Keep this in sync with X86FrameLowering::emitPrologue.
472 int ParentFrameOffset =
473 16 + 8 + MF->getFrameInfo()->getMaxCallFrameSize();
474 OS.EmitIntValue(ParentFrameOffset, 4); // ParentFrameOffset
480 // IPToStateMapEntry {
484 if (IPToStateXData) {
485 OS.EmitLabel(IPToStateXData);
486 for (auto &IPStatePair : IPToStateTable) {
487 OS.EmitValue(IPStatePair.first, 4); // IP
488 OS.EmitIntValue(IPStatePair.second, 4); // State
493 void WinException::computeIP2StateTable(
494 const MachineFunction *MF, WinEHFuncInfo &FuncInfo,
495 SmallVectorImpl<std::pair<const MCExpr *, int>> &IPToStateTable) {
496 // Whether there is a potentially throwing instruction (currently this means
497 // an ordinary call) between the end of the previous try-range and now.
498 bool SawPotentiallyThrowing = true;
500 // Remember what state we were in the last time we found a begin try label.
501 // This allows us to coalesce many nearby invokes with the same state into one
503 int LastEHState = -1;
504 MCSymbol *LastEndLabel = Asm->getFunctionBegin();
505 assert(LastEndLabel && "need local function start label");
507 // Indicate that all calls from the prologue to the first invoke unwind to
508 // caller. We handle this as a special case since other ranges starting at end
509 // labels need to use LtmpN+1.
510 IPToStateTable.push_back(std::make_pair(create32bitRef(LastEndLabel), -1));
512 for (const auto &MBB : *MF) {
513 // FIXME: Do we need to emit entries for funclet base states?
515 for (const auto &MI : MBB) {
516 // Find all the EH_LABEL instructions, tracking if we've crossed a
517 // potentially throwing call since the last label.
518 if (!MI.isEHLabel()) {
520 SawPotentiallyThrowing |= !callToNoUnwindFunction(&MI);
524 // If this was an end label, return SawPotentiallyThrowing to the start
525 // state and keep going. Otherwise, we will consider the call between the
526 // begin/end labels to be a potentially throwing call and generate extra
528 MCSymbol *Label = MI.getOperand(0).getMCSymbol();
529 if (Label == LastEndLabel)
530 SawPotentiallyThrowing = false;
532 // Check if this was a begin label. Otherwise, it must be an end label or
533 // some random label, and we should continue.
534 auto StateAndEnd = FuncInfo.InvokeToStateMap.find(Label);
535 if (StateAndEnd == FuncInfo.InvokeToStateMap.end())
538 // Extract the state and end label.
541 std::tie(State, EndLabel) = StateAndEnd->second;
543 // If there was a potentially throwing call between this begin label and
544 // the last end label, we need an extra base state entry to indicate that
545 // those calls unwind directly to the caller.
546 if (SawPotentiallyThrowing && LastEHState != -1) {
547 IPToStateTable.push_back(
548 std::make_pair(getLabelPlusOne(LastEndLabel), -1));
549 SawPotentiallyThrowing = false;
553 // Emit an entry indicating that PCs after 'Label' have this EH state.
554 if (State != LastEHState)
555 IPToStateTable.push_back(std::make_pair(create32bitRef(Label), State));
557 LastEndLabel = EndLabel;
561 if (LastEndLabel != Asm->getFunctionBegin()) {
562 // Indicate that all calls from the last invoke until the epilogue unwind to
563 // caller. This also ensures that we have at least one ip2state entry, if
564 // somehow all invokes were deleted during CodeGen.
565 IPToStateTable.push_back(std::make_pair(getLabelPlusOne(LastEndLabel), -1));
569 void WinException::emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo,
570 StringRef FLinkageName) {
571 // Outlined helpers called by the EH runtime need to know the offset of the EH
572 // registration in order to recover the parent frame pointer. Now that we know
573 // we've code generated the parent, we can emit the label assignment that
574 // those helpers use to get the offset of the registration node.
575 assert(FuncInfo.EHRegNodeEscapeIndex != INT_MAX &&
576 "no EH reg node localescape index");
577 MCSymbol *ParentFrameOffset =
578 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(FLinkageName);
579 MCSymbol *RegistrationOffsetSym = Asm->OutContext.getOrCreateFrameAllocSymbol(
580 FLinkageName, FuncInfo.EHRegNodeEscapeIndex);
581 const MCExpr *RegistrationOffsetSymRef =
582 MCSymbolRefExpr::create(RegistrationOffsetSym, Asm->OutContext);
583 Asm->OutStreamer->EmitAssignment(ParentFrameOffset, RegistrationOffsetSymRef);
586 /// Emit the language-specific data that _except_handler3 and 4 expect. This is
587 /// functionally equivalent to the __C_specific_handler table, except it is
588 /// indexed by state number instead of IP.
589 void WinException::emitExceptHandlerTable(const MachineFunction *MF) {
590 MCStreamer &OS = *Asm->OutStreamer;
591 const Function *F = MF->getFunction();
592 StringRef FLinkageName = GlobalValue::getRealLinkageName(F->getName());
594 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
595 emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
597 // Emit the __ehtable label that we use for llvm.x86.seh.lsda.
598 MCSymbol *LSDALabel = Asm->OutContext.getOrCreateLSDASymbol(FLinkageName);
599 OS.EmitValueToAlignment(4);
600 OS.EmitLabel(LSDALabel);
602 const Function *Per =
603 dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
604 StringRef PerName = Per->getName();
606 if (PerName == "_except_handler4") {
607 // The LSDA for _except_handler4 starts with this struct, followed by the
610 // struct EH4ScopeTable {
611 // int32_t GSCookieOffset;
612 // int32_t GSCookieXOROffset;
613 // int32_t EHCookieOffset;
614 // int32_t EHCookieXOROffset;
615 // ScopeTableEntry ScopeRecord[];
618 // Only the EHCookieOffset field appears to vary, and it appears to be the
619 // offset from the final saved SP value to the retaddr.
620 OS.EmitIntValue(-2, 4);
621 OS.EmitIntValue(0, 4);
623 OS.EmitIntValue(9999, 4);
624 OS.EmitIntValue(0, 4);
628 if (!FuncInfo.SEHUnwindMap.empty()) {
629 for (SEHUnwindMapEntry &UME : FuncInfo.SEHUnwindMap) {
630 MCSymbol *ExceptOrFinally =
631 UME.Handler.get<MachineBasicBlock *>()->getSymbol();
632 OS.EmitIntValue(UME.ToState, 4); // ToState
633 OS.EmitValue(create32bitRef(UME.Filter), 4); // Filter
634 OS.EmitValue(create32bitRef(ExceptOrFinally), 4); // Except/Finally
638 // FIXME: The following code is for the old landingpad-based SEH
639 // implementation. Remove it when possible.
641 // Build a list of pointers to LandingPadInfos and then sort by WinEHState.
642 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
643 SmallVector<const LandingPadInfo *, 4> LPads;
644 LPads.reserve((PadInfos.size()));
645 for (const LandingPadInfo &LPInfo : PadInfos)
646 LPads.push_back(&LPInfo);
647 std::sort(LPads.begin(), LPads.end(),
648 [](const LandingPadInfo *L, const LandingPadInfo *R) {
649 return L->WinEHState < R->WinEHState;
652 // For each action in each lpad, emit one of these:
653 // struct ScopeTableEntry {
654 // int32_t EnclosingLevel;
655 // int32_t (__cdecl *Filter)();
656 // void *HandlerOrFinally;
659 // The "outermost" action will use BaseState as its enclosing level. Each
660 // other action will refer to the previous state as its enclosing level.
662 for (const LandingPadInfo *LPInfo : LPads) {
663 int EnclosingLevel = BaseState;
664 assert(CurState + int(LPInfo->SEHHandlers.size()) - 1 ==
665 LPInfo->WinEHState &&
666 "gaps in the SEH scope table");
667 for (auto I = LPInfo->SEHHandlers.rbegin(), E = LPInfo->SEHHandlers.rend();
669 const SEHHandler &Handler = *I;
670 const BlockAddress *BA = Handler.RecoverBA;
671 const Function *F = Handler.FilterOrFinally;
672 assert(F && "cannot catch all in 32-bit SEH without filter function");
673 const MCExpr *FilterOrNull =
674 create32bitRef(BA ? Asm->getSymbol(F) : nullptr);
675 const MCExpr *ExceptOrFinally = create32bitRef(
676 BA ? Asm->GetBlockAddressSymbol(BA) : Asm->getSymbol(F));
678 OS.EmitIntValue(EnclosingLevel, 4);
679 OS.EmitValue(FilterOrNull, 4);
680 OS.EmitValue(ExceptOrFinally, 4);
682 // The next state unwinds to this state.
683 EnclosingLevel = CurState;