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/COFF.h"
34 #include "llvm/Support/Dwarf.h"
35 #include "llvm/Support/ErrorHandling.h"
36 #include "llvm/Support/FormattedStream.h"
37 #include "llvm/Target/TargetFrameLowering.h"
38 #include "llvm/Target/TargetLoweringObjectFile.h"
39 #include "llvm/Target/TargetOptions.h"
40 #include "llvm/Target/TargetRegisterInfo.h"
43 WinException::WinException(AsmPrinter *A) : EHStreamer(A) {
44 // MSVC's EH tables are always composed of 32-bit words. All known 64-bit
45 // platforms use an imagerel32 relocation to refer to symbols.
46 useImageRel32 = (A->getDataLayout().getPointerSizeInBits() == 64);
49 WinException::~WinException() {}
51 /// endModule - Emit all exception information that should come after the
53 void WinException::endModule() {
54 auto &OS = *Asm->OutStreamer;
55 const Module *M = MMI->getModule();
56 for (const Function &F : *M)
57 if (F.hasFnAttribute("safeseh"))
58 OS.EmitCOFFSafeSEH(Asm->getSymbol(&F));
61 void WinException::beginFunction(const MachineFunction *MF) {
62 shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
64 // If any landing pads survive, we need an EH table.
65 bool hasLandingPads = !MMI->getLandingPads().empty();
66 bool hasEHFunclets = MMI->hasEHFunclets();
68 const Function *F = MF->getFunction();
69 const Function *ParentF = MMI->getWinEHParent(F);
71 shouldEmitMoves = Asm->needsSEHMoves();
73 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
74 unsigned PerEncoding = TLOF.getPersonalityEncoding();
75 const Function *Per = nullptr;
76 if (F->hasPersonalityFn())
77 Per = dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
79 bool forceEmitPersonality =
80 F->hasPersonalityFn() && !isNoOpWithoutInvoke(classifyEHPersonality(Per)) &&
81 F->needsUnwindTableEntry();
83 shouldEmitPersonality =
84 forceEmitPersonality || ((hasLandingPads || hasEHFunclets) &&
85 PerEncoding != dwarf::DW_EH_PE_omit && Per);
87 unsigned LSDAEncoding = TLOF.getLSDAEncoding();
88 shouldEmitLSDA = shouldEmitPersonality &&
89 LSDAEncoding != dwarf::DW_EH_PE_omit;
91 // If we're not using CFI, we don't want the CFI or the personality, but we
92 // might want EH tables if we had EH pads.
93 // FIXME: If WinEHPrepare outlined something, we should emit the LSDA. Remove
94 // this once WinEHPrepare stops doing that.
95 if (!Asm->MAI->usesWindowsCFI()) {
97 hasEHFunclets || (F->hasFnAttribute("wineh-parent") && F == ParentF);
98 shouldEmitPersonality = false;
102 beginFunclet(MF->front(), Asm->CurrentFnSym);
105 /// endFunction - Gather and emit post-function exception information.
107 void WinException::endFunction(const MachineFunction *MF) {
108 if (!shouldEmitPersonality && !shouldEmitMoves && !shouldEmitLSDA)
111 const Function *F = MF->getFunction();
112 EHPersonality Per = EHPersonality::Unknown;
113 if (F->hasPersonalityFn())
114 Per = classifyEHPersonality(F->getPersonalityFn());
116 // Get rid of any dead landing pads if we're not using a Windows EH scheme. In
117 // Windows EH schemes, the landing pad is not actually reachable. It only
118 // exists so that we can emit the right table data.
119 if (!isMSVCEHPersonality(Per))
120 MMI->TidyLandingPads();
124 // endFunclet will emit the necessary .xdata tables for x64 SEH.
125 if (Per == EHPersonality::MSVC_Win64SEH && MMI->hasEHFunclets())
128 if (shouldEmitPersonality || shouldEmitLSDA) {
129 Asm->OutStreamer->PushSection();
131 // Just switch sections to the right xdata section. This use of CurrentFnSym
132 // assumes that we only emit the LSDA when ending the parent function.
133 MCSection *XData = WinEH::UnwindEmitter::getXDataSection(Asm->CurrentFnSym,
135 Asm->OutStreamer->SwitchSection(XData);
137 // Emit the tables appropriate to the personality function in use. If we
138 // don't recognize the personality, assume it uses an Itanium-style LSDA.
139 if (Per == EHPersonality::MSVC_Win64SEH)
140 emitCSpecificHandlerTable(MF);
141 else if (Per == EHPersonality::MSVC_X86SEH)
142 emitExceptHandlerTable(MF);
143 else if (Per == EHPersonality::MSVC_CXX)
144 emitCXXFrameHandler3Table(MF);
146 emitExceptionTable();
148 Asm->OutStreamer->PopSection();
152 /// Retreive the MCSymbol for a GlobalValue or MachineBasicBlock. GlobalValues
153 /// are used in the old WinEH scheme, and they will be removed eventually.
154 static MCSymbol *getMCSymbolForMBBOrGV(AsmPrinter *Asm, ValueOrMBB Handler) {
157 if (Handler.is<const MachineBasicBlock *>()) {
158 auto *MBB = Handler.get<const MachineBasicBlock *>();
159 assert(MBB->isEHFuncletEntry());
161 // Give catches and cleanups a name based off of their parent function and
162 // their funclet entry block's number.
163 const MachineFunction *MF = MBB->getParent();
164 const Function *F = MF->getFunction();
165 StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
166 MCContext &Ctx = MF->getContext();
167 StringRef HandlerPrefix = MBB->isCleanupFuncletEntry() ? "dtor" : "catch";
168 return Ctx.getOrCreateSymbol("?" + HandlerPrefix + "$" +
169 Twine(MBB->getNumber()) + "@?0?" +
170 FuncLinkageName + "@4HA");
172 return Asm->getSymbol(cast<GlobalValue>(Handler.get<const Value *>()));
175 void WinException::beginFunclet(const MachineBasicBlock &MBB,
177 CurrentFuncletEntry = &MBB;
179 const Function *F = Asm->MF->getFunction();
180 // If a symbol was not provided for the funclet, invent one.
182 Sym = getMCSymbolForMBBOrGV(Asm, &MBB);
184 // Describe our funclet symbol as a function with internal linkage.
185 Asm->OutStreamer->BeginCOFFSymbolDef(Sym);
186 Asm->OutStreamer->EmitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC);
187 Asm->OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
188 << COFF::SCT_COMPLEX_TYPE_SHIFT);
189 Asm->OutStreamer->EndCOFFSymbolDef();
191 // We want our funclet's entry point to be aligned such that no nops will be
192 // present after the label.
193 Asm->EmitAlignment(std::max(Asm->MF->getAlignment(), MBB.getAlignment()),
196 // Now that we've emitted the alignment directive, point at our funclet.
197 Asm->OutStreamer->EmitLabel(Sym);
200 // Mark 'Sym' as starting our funclet.
201 if (shouldEmitMoves || shouldEmitPersonality)
202 Asm->OutStreamer->EmitWinCFIStartProc(Sym);
204 if (shouldEmitPersonality) {
205 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
206 const Function *PerFn = nullptr;
208 // Determine which personality routine we are using for this funclet.
209 if (F->hasPersonalityFn())
210 PerFn = dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
211 const MCSymbol *PersHandlerSym =
212 TLOF.getCFIPersonalitySymbol(PerFn, *Asm->Mang, Asm->TM, MMI);
214 // Classify the personality routine so that we may reason about it.
215 EHPersonality Per = EHPersonality::Unknown;
216 if (F->hasPersonalityFn())
217 Per = classifyEHPersonality(F->getPersonalityFn());
219 // Do not emit a .seh_handler directive if it is a C++ cleanup funclet.
220 if (Per != EHPersonality::MSVC_CXX ||
221 !CurrentFuncletEntry->isCleanupFuncletEntry())
222 Asm->OutStreamer->EmitWinEHHandler(PersHandlerSym, true, true);
226 void WinException::endFunclet() {
227 // No funclet to process? Great, we have nothing to do.
228 if (!CurrentFuncletEntry)
231 if (shouldEmitMoves || shouldEmitPersonality) {
232 const Function *F = Asm->MF->getFunction();
233 EHPersonality Per = EHPersonality::Unknown;
234 if (F->hasPersonalityFn())
235 Per = classifyEHPersonality(F->getPersonalityFn());
237 // The .seh_handlerdata directive implicitly switches section, push the
238 // current section so that we may return to it.
239 Asm->OutStreamer->PushSection();
241 // Emit an UNWIND_INFO struct describing the prologue.
242 Asm->OutStreamer->EmitWinEHHandlerData();
244 if (Per == EHPersonality::MSVC_CXX && shouldEmitPersonality &&
245 !CurrentFuncletEntry->isCleanupFuncletEntry()) {
246 // If this is a C++ catch funclet (or the parent function),
247 // emit a reference to the LSDA for the parent function.
248 StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
249 MCSymbol *FuncInfoXData = Asm->OutContext.getOrCreateSymbol(
250 Twine("$cppxdata$", FuncLinkageName));
251 Asm->OutStreamer->EmitValue(create32bitRef(FuncInfoXData), 4);
252 } else if (Per == EHPersonality::MSVC_Win64SEH && MMI->hasEHFunclets() &&
253 !CurrentFuncletEntry->isEHFuncletEntry()) {
254 // If this is the parent function in Win64 SEH, emit the LSDA immediately
255 // following .seh_handlerdata.
256 emitCSpecificHandlerTable(Asm->MF);
259 // Switch back to the previous section now that we are done writing to
261 Asm->OutStreamer->PopSection();
263 // Emit a .seh_endproc directive to mark the end of the function.
264 Asm->OutStreamer->EmitWinCFIEndProc();
267 // Let's make sure we don't try to end the same funclet twice.
268 CurrentFuncletEntry = nullptr;
271 const MCExpr *WinException::create32bitRef(const MCSymbol *Value) {
273 return MCConstantExpr::create(0, Asm->OutContext);
274 return MCSymbolRefExpr::create(Value, useImageRel32
275 ? MCSymbolRefExpr::VK_COFF_IMGREL32
276 : MCSymbolRefExpr::VK_None,
280 const MCExpr *WinException::create32bitRef(const Value *V) {
282 return MCConstantExpr::create(0, Asm->OutContext);
283 // FIXME: Delete the GlobalValue case once the new IR is fully functional.
284 if (const auto *GV = dyn_cast<GlobalValue>(V))
285 return create32bitRef(Asm->getSymbol(GV));
286 return create32bitRef(MMI->getAddrLabelSymbol(cast<BasicBlock>(V)));
289 const MCExpr *WinException::getLabelPlusOne(MCSymbol *Label) {
290 return MCBinaryExpr::createAdd(create32bitRef(Label),
291 MCConstantExpr::create(1, Asm->OutContext),
295 /// Information describing an invoke range.
297 MCSymbol *BeginLabel = nullptr;
298 MCSymbol *EndLabel = nullptr;
301 /// If we saw a potentially throwing call between this range and the last
303 bool SawPotentiallyThrowing = false;
306 /// Iterator over the begin/end label pairs of invokes within a basic block.
307 class InvokeLabelIterator {
309 InvokeLabelIterator(WinEHFuncInfo &EHInfo,
310 MachineBasicBlock::const_iterator MBBI,
311 MachineBasicBlock::const_iterator MBBIEnd)
312 : EHInfo(EHInfo), MBBI(MBBI), MBBIEnd(MBBIEnd) {
317 bool operator==(const InvokeLabelIterator &o) const { return MBBI == o.MBBI; }
318 bool operator!=(const InvokeLabelIterator &o) const { return MBBI != o.MBBI; }
319 InvokeRange &operator*() { return CurRange; }
320 InvokeRange *operator->() { return &CurRange; }
321 InvokeLabelIterator &operator++() { return scan(); }
324 // Scan forward to find the next invoke range, or hit the end iterator.
325 InvokeLabelIterator &scan();
327 WinEHFuncInfo &EHInfo;
328 MachineBasicBlock::const_iterator MBBI;
329 MachineBasicBlock::const_iterator MBBIEnd;
330 InvokeRange CurRange;
333 /// Invoke label range iteration logic. Increment MBBI until we find the next
334 /// EH_LABEL pair, and then update MBBI to point after the end label.
335 InvokeLabelIterator &InvokeLabelIterator::scan() {
337 CurRange = InvokeRange{};
339 for (const MachineInstr &MI : make_range(MBBI, MBBIEnd)) {
340 // Remember if we had to cross a potentially throwing call instruction that
341 // must unwind to caller.
343 CurRange.SawPotentiallyThrowing |=
344 !EHStreamer::callToNoUnwindFunction(&MI);
347 // Find the next EH_LABEL instruction.
351 // If this is a begin label, break out with the state and end label.
352 // Otherwise this is probably a CFI EH_LABEL that we should continue past.
353 MCSymbol *Label = MI.getOperand(0).getMCSymbol();
354 auto StateAndEnd = EHInfo.InvokeToStateMap.find(Label);
355 if (StateAndEnd == EHInfo.InvokeToStateMap.end())
357 MBBI = MachineBasicBlock::const_iterator(&MI);
358 CurRange.BeginLabel = Label;
359 CurRange.EndLabel = StateAndEnd->second.second;
360 CurRange.State = StateAndEnd->second.first;
364 // If we didn't find a begin label, we are done, return the end iterator.
365 if (!CurRange.BeginLabel) {
370 // If this is a begin label, update MBBI to point past the end label.
371 for (; MBBI != MBBIEnd; ++MBBI)
372 if (MBBI->isEHLabel() &&
373 MBBI->getOperand(0).getMCSymbol() == CurRange.EndLabel)
378 /// Utility for making a range for all the invoke ranges.
379 static iterator_range<InvokeLabelIterator>
380 invoke_ranges(WinEHFuncInfo &EHInfo, const MachineBasicBlock &MBB) {
381 return make_range(InvokeLabelIterator(EHInfo, MBB.begin(), MBB.end()),
382 InvokeLabelIterator(EHInfo, MBB.end(), MBB.end()));
385 /// Emit the language-specific data that __C_specific_handler expects. This
386 /// handler lives in the x64 Microsoft C runtime and allows catching or cleaning
387 /// up after faults with __try, __except, and __finally. The typeinfo values
388 /// are not really RTTI data, but pointers to filter functions that return an
389 /// integer (1, 0, or -1) indicating how to handle the exception. For __finally
390 /// blocks and other cleanups, the landing pad label is zero, and the filter
391 /// function is actually a cleanup handler with the same prototype. A catch-all
392 /// entry is modeled with a null filter function field and a non-zero landing
395 /// Possible filter function return values:
396 /// EXCEPTION_EXECUTE_HANDLER (1):
397 /// Jump to the landing pad label after cleanups.
398 /// EXCEPTION_CONTINUE_SEARCH (0):
399 /// Continue searching this table or continue unwinding.
400 /// EXCEPTION_CONTINUE_EXECUTION (-1):
401 /// Resume execution at the trapping PC.
403 /// Inferred table structure:
407 /// imagerel32 LabelStart;
408 /// imagerel32 LabelEnd;
409 /// imagerel32 FilterOrFinally; // One means catch-all.
410 /// imagerel32 LabelLPad; // Zero means __finally.
411 /// } Entries[NumEntries];
413 void WinException::emitCSpecificHandlerTable(const MachineFunction *MF) {
414 auto &OS = *Asm->OutStreamer;
415 MCContext &Ctx = Asm->OutContext;
417 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(MF->getFunction());
418 if (!FuncInfo.SEHUnwindMap.empty()) {
419 // Remember what state we were in the last time we found a begin try label.
420 // This allows us to coalesce many nearby invokes with the same state into
422 int LastEHState = -1;
423 MCSymbol *LastBeginLabel = nullptr;
424 MCSymbol *LastEndLabel = nullptr;
426 // Use the assembler to compute the number of table entries through label
427 // difference and division.
428 MCSymbol *TableBegin = Ctx.createTempSymbol("lsda_begin");
429 MCSymbol *TableEnd = Ctx.createTempSymbol("lsda_end");
430 const MCExpr *LabelDiff =
431 MCBinaryExpr::createSub(MCSymbolRefExpr::create(TableEnd, Ctx),
432 MCSymbolRefExpr::create(TableBegin, Ctx), Ctx);
433 const MCExpr *EntrySize = MCConstantExpr::create(16, Ctx);
434 const MCExpr *EntryCount =
435 MCBinaryExpr::createDiv(LabelDiff, EntrySize, Ctx);
436 OS.EmitValue(EntryCount, 4);
438 OS.EmitLabel(TableBegin);
440 // Iterate over all the invoke try ranges. Unlike MSVC, LLVM currently only
441 // models exceptions from invokes. LLVM also allows arbitrary reordering of
442 // the code, so our tables end up looking a bit different. Rather than
443 // trying to match MSVC's tables exactly, we emit a denormalized table. For
444 // each range of invokes in the same state, we emit table entries for all
445 // the actions that would be taken in that state. This means our tables are
446 // slightly bigger, which is OK.
447 for (const auto &MBB : *MF) {
448 for (InvokeRange &I : invoke_ranges(FuncInfo, MBB)) {
449 // If this invoke is in the same state as the last invoke and there were
450 // no non-throwing calls between it, extend the range to include both
452 if (!I.SawPotentiallyThrowing && I.State == LastEHState) {
453 LastEndLabel = I.EndLabel;
457 // If this invoke ends a previous one, emit all the actions for this
459 if (LastEHState != -1) {
460 assert(LastBeginLabel && LastEndLabel);
461 for (int State = LastEHState; State != -1;) {
462 SEHUnwindMapEntry &UME = FuncInfo.SEHUnwindMap[State];
463 const MCExpr *FilterOrFinally;
464 const MCExpr *ExceptOrNull;
465 auto *Handler = UME.Handler.get<MachineBasicBlock *>();
467 FilterOrFinally = create32bitRef(Handler->getSymbol());
468 ExceptOrNull = MCConstantExpr::create(0, Ctx);
470 // For an except, the filter can be 1 (catch-all) or a function
472 FilterOrFinally = UME.Filter ? create32bitRef(UME.Filter)
473 : MCConstantExpr::create(1, Ctx);
474 ExceptOrNull = create32bitRef(Handler->getSymbol());
477 OS.EmitValue(getLabelPlusOne(LastBeginLabel), 4);
478 OS.EmitValue(getLabelPlusOne(LastEndLabel), 4);
479 OS.EmitValue(FilterOrFinally, 4);
480 OS.EmitValue(ExceptOrNull, 4);
486 LastBeginLabel = I.BeginLabel;
487 LastEndLabel = I.EndLabel;
488 LastEHState = I.State;
491 OS.EmitLabel(TableEnd);
495 // Simplifying assumptions for first implementation:
496 // - Cleanups are not implemented.
497 // - Filters are not implemented.
499 // The Itanium LSDA table sorts similar landing pads together to simplify the
500 // actions table, but we don't need that.
501 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
502 SmallVector<const LandingPadInfo *, 64> LandingPads;
503 LandingPads.reserve(PadInfos.size());
504 for (const auto &LP : PadInfos)
505 LandingPads.push_back(&LP);
507 // Compute label ranges for call sites as we would for the Itanium LSDA, but
508 // use an all zero action table because we aren't using these actions.
509 SmallVector<unsigned, 64> FirstActions;
510 FirstActions.resize(LandingPads.size());
511 SmallVector<CallSiteEntry, 64> CallSites;
512 computeCallSiteTable(CallSites, LandingPads, FirstActions);
514 MCSymbol *EHFuncBeginSym = Asm->getFunctionBegin();
515 MCSymbol *EHFuncEndSym = Asm->getFunctionEnd();
517 // Emit the number of table entries.
518 unsigned NumEntries = 0;
519 for (const CallSiteEntry &CSE : CallSites) {
521 continue; // Ignore gaps.
522 NumEntries += CSE.LPad->SEHHandlers.size();
524 OS.EmitIntValue(NumEntries, 4);
526 // If there are no actions, we don't need to iterate again.
530 // Emit the four-label records for each call site entry. The table has to be
531 // sorted in layout order, and the call sites should already be sorted.
532 for (const CallSiteEntry &CSE : CallSites) {
533 // Ignore gaps. Unlike the Itanium model, unwinding through a frame without
534 // an EH table entry will propagate the exception rather than terminating
538 const LandingPadInfo *LPad = CSE.LPad;
540 // Compute the label range. We may reuse the function begin and end labels
541 // rather than forming new ones.
542 const MCExpr *Begin =
543 create32bitRef(CSE.BeginLabel ? CSE.BeginLabel : EHFuncBeginSym);
546 // The interval is half-open, so we have to add one to include the return
547 // address of the last invoke in the range.
548 End = getLabelPlusOne(CSE.EndLabel);
550 End = create32bitRef(EHFuncEndSym);
553 // Emit an entry for each action.
554 for (SEHHandler Handler : LPad->SEHHandlers) {
555 OS.EmitValue(Begin, 4);
556 OS.EmitValue(End, 4);
558 // Emit the filter or finally function pointer, if present. Otherwise,
559 // emit '1' to indicate a catch-all.
560 const Function *F = Handler.FilterOrFinally;
562 OS.EmitValue(create32bitRef(Asm->getSymbol(F)), 4);
564 OS.EmitIntValue(1, 4);
566 // Emit the recovery address, if present. Otherwise, this must be a
568 const BlockAddress *BA = Handler.RecoverBA;
571 create32bitRef(Asm->GetBlockAddressSymbol(BA)), 4);
573 OS.EmitIntValue(0, 4);
578 void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
579 const Function *F = MF->getFunction();
580 auto &OS = *Asm->OutStreamer;
581 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
583 StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
585 SmallVector<std::pair<const MCExpr *, int>, 4> IPToStateTable;
586 MCSymbol *FuncInfoXData = nullptr;
587 if (shouldEmitPersonality) {
588 // If we're 64-bit, emit a pointer to the C++ EH data, and build a map from
589 // IPs to state numbers.
591 Asm->OutContext.getOrCreateSymbol(Twine("$cppxdata$", FuncLinkageName));
592 computeIP2StateTable(MF, FuncInfo, IPToStateTable);
594 FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(FuncLinkageName);
595 emitEHRegistrationOffsetLabel(FuncInfo, FuncLinkageName);
598 MCSymbol *UnwindMapXData = nullptr;
599 MCSymbol *TryBlockMapXData = nullptr;
600 MCSymbol *IPToStateXData = nullptr;
601 if (!FuncInfo.UnwindMap.empty())
602 UnwindMapXData = Asm->OutContext.getOrCreateSymbol(
603 Twine("$stateUnwindMap$", FuncLinkageName));
604 if (!FuncInfo.TryBlockMap.empty())
606 Asm->OutContext.getOrCreateSymbol(Twine("$tryMap$", FuncLinkageName));
607 if (!IPToStateTable.empty())
609 Asm->OutContext.getOrCreateSymbol(Twine("$ip2state$", FuncLinkageName));
612 // uint32_t MagicNumber
614 // UnwindMapEntry *UnwindMap;
615 // uint32_t NumTryBlocks;
616 // TryBlockMapEntry *TryBlockMap;
617 // uint32_t IPMapEntries; // always 0 for x86
618 // IPToStateMapEntry *IPToStateMap; // always 0 for x86
619 // uint32_t UnwindHelp; // non-x86 only
620 // ESTypeList *ESTypeList;
623 // EHFlags & 1 -> Synchronous exceptions only, no async exceptions.
624 // EHFlags & 2 -> ???
625 // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue.
626 OS.EmitValueToAlignment(4);
627 OS.EmitLabel(FuncInfoXData);
628 OS.EmitIntValue(0x19930522, 4); // MagicNumber
629 OS.EmitIntValue(FuncInfo.UnwindMap.size(), 4); // MaxState
630 OS.EmitValue(create32bitRef(UnwindMapXData), 4); // UnwindMap
631 OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4); // NumTryBlocks
632 OS.EmitValue(create32bitRef(TryBlockMapXData), 4); // TryBlockMap
633 OS.EmitIntValue(IPToStateTable.size(), 4); // IPMapEntries
634 OS.EmitValue(create32bitRef(IPToStateXData), 4); // IPToStateMap
635 if (Asm->MAI->usesWindowsCFI())
636 OS.EmitIntValue(FuncInfo.UnwindHelpFrameOffset, 4); // UnwindHelp
637 OS.EmitIntValue(0, 4); // ESTypeList
638 OS.EmitIntValue(1, 4); // EHFlags
644 if (UnwindMapXData) {
645 OS.EmitLabel(UnwindMapXData);
646 for (const WinEHUnwindMapEntry &UME : FuncInfo.UnwindMap) {
647 MCSymbol *CleanupSym = getMCSymbolForMBBOrGV(Asm, UME.Cleanup);
648 OS.EmitIntValue(UME.ToState, 4); // ToState
649 OS.EmitValue(create32bitRef(CleanupSym), 4); // Action
656 // int32_t CatchHigh;
657 // int32_t NumCatches;
658 // HandlerType *HandlerArray;
660 if (TryBlockMapXData) {
661 OS.EmitLabel(TryBlockMapXData);
662 SmallVector<MCSymbol *, 1> HandlerMaps;
663 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
664 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
666 MCSymbol *HandlerMapXData = nullptr;
667 if (!TBME.HandlerArray.empty())
669 Asm->OutContext.getOrCreateSymbol(Twine("$handlerMap$")
672 .concat(FuncLinkageName));
673 HandlerMaps.push_back(HandlerMapXData);
675 // TBMEs should form intervals.
676 assert(0 <= TBME.TryLow && "bad trymap interval");
677 assert(TBME.TryLow <= TBME.TryHigh && "bad trymap interval");
678 assert(TBME.TryHigh < TBME.CatchHigh && "bad trymap interval");
679 assert(TBME.CatchHigh < int(FuncInfo.UnwindMap.size()) &&
680 "bad trymap interval");
682 OS.EmitIntValue(TBME.TryLow, 4); // TryLow
683 OS.EmitIntValue(TBME.TryHigh, 4); // TryHigh
684 OS.EmitIntValue(TBME.CatchHigh, 4); // CatchHigh
685 OS.EmitIntValue(TBME.HandlerArray.size(), 4); // NumCatches
686 OS.EmitValue(create32bitRef(HandlerMapXData), 4); // HandlerArray
689 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
690 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
691 MCSymbol *HandlerMapXData = HandlerMaps[I];
692 if (!HandlerMapXData)
695 // int32_t Adjectives;
696 // TypeDescriptor *Type;
697 // int32_t CatchObjOffset;
698 // void (*Handler)();
699 // int32_t ParentFrameOffset; // x64 only
701 OS.EmitLabel(HandlerMapXData);
702 for (const WinEHHandlerType &HT : TBME.HandlerArray) {
703 // Get the frame escape label with the offset of the catch object. If
704 // the index is -1, then there is no catch object, and we should emit an
705 // offset of zero, indicating that no copy will occur.
706 const MCExpr *FrameAllocOffsetRef = nullptr;
707 if (HT.CatchObjRecoverIdx >= 0) {
708 MCSymbol *FrameAllocOffset =
709 Asm->OutContext.getOrCreateFrameAllocSymbol(
710 FuncLinkageName, HT.CatchObjRecoverIdx);
711 FrameAllocOffsetRef = MCSymbolRefExpr::create(
712 FrameAllocOffset, MCSymbolRefExpr::VK_None, Asm->OutContext);
713 } else if (HT.CatchObj.FrameOffset != INT_MAX) {
714 int Offset = HT.CatchObj.FrameOffset;
715 // For 32-bit, the catch object offset is relative to the end of the
716 // EH registration node. For 64-bit, it's relative to SP at the end of
718 if (!shouldEmitPersonality) {
719 assert(FuncInfo.EHRegNodeEndOffset != INT_MAX);
720 Offset += FuncInfo.EHRegNodeEndOffset;
722 FrameAllocOffsetRef = MCConstantExpr::create(Offset, Asm->OutContext);
724 FrameAllocOffsetRef = MCConstantExpr::create(0, Asm->OutContext);
727 MCSymbol *HandlerSym = getMCSymbolForMBBOrGV(Asm, HT.Handler);
729 OS.EmitIntValue(HT.Adjectives, 4); // Adjectives
730 OS.EmitValue(create32bitRef(HT.TypeDescriptor), 4); // Type
731 OS.EmitValue(FrameAllocOffsetRef, 4); // CatchObjOffset
732 OS.EmitValue(create32bitRef(HandlerSym), 4); // Handler
734 if (shouldEmitPersonality) {
735 // With the new IR, this is always 16 + 8 + getMaxCallFrameSize().
736 // Keep this in sync with X86FrameLowering::emitPrologue.
737 int ParentFrameOffset =
738 16 + 8 + MF->getFrameInfo()->getMaxCallFrameSize();
739 OS.EmitIntValue(ParentFrameOffset, 4); // ParentFrameOffset
745 // IPToStateMapEntry {
749 if (IPToStateXData) {
750 OS.EmitLabel(IPToStateXData);
751 for (auto &IPStatePair : IPToStateTable) {
752 OS.EmitValue(IPStatePair.first, 4); // IP
753 OS.EmitIntValue(IPStatePair.second, 4); // State
758 void WinException::computeIP2StateTable(
759 const MachineFunction *MF, WinEHFuncInfo &FuncInfo,
760 SmallVectorImpl<std::pair<const MCExpr *, int>> &IPToStateTable) {
761 // Remember what state we were in the last time we found a begin try label.
762 // This allows us to coalesce many nearby invokes with the same state into one
764 int LastEHState = -1;
765 MCSymbol *LastEndLabel = Asm->getFunctionBegin();
766 assert(LastEndLabel && "need local function start label");
768 // Indicate that all calls from the prologue to the first invoke unwind to
769 // caller. We handle this as a special case since other ranges starting at end
770 // labels need to use LtmpN+1.
771 IPToStateTable.push_back(std::make_pair(create32bitRef(LastEndLabel), -1));
773 for (const auto &MBB : *MF) {
774 // FIXME: Do we need to emit entries for funclet base states?
776 for (InvokeRange &I : invoke_ranges(FuncInfo, MBB)) {
777 assert(I.BeginLabel && I.EndLabel);
778 // If there was a potentially throwing call between this begin label and
779 // the last end label, we need an extra base state entry to indicate that
780 // those calls unwind directly to the caller.
781 if (I.SawPotentiallyThrowing && LastEHState != -1) {
782 IPToStateTable.push_back(
783 std::make_pair(getLabelPlusOne(LastEndLabel), -1));
787 // Emit an entry indicating that PCs after 'Label' have this EH state.
788 if (I.State != LastEHState)
789 IPToStateTable.push_back(
790 std::make_pair(create32bitRef(I.BeginLabel), I.State));
791 LastEHState = I.State;
792 LastEndLabel = I.EndLabel;
796 if (LastEndLabel != Asm->getFunctionBegin()) {
797 // Indicate that all calls from the last invoke until the epilogue unwind to
798 // caller. This also ensures that we have at least one ip2state entry, if
799 // somehow all invokes were deleted during CodeGen.
800 IPToStateTable.push_back(std::make_pair(getLabelPlusOne(LastEndLabel), -1));
804 void WinException::emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo,
805 StringRef FLinkageName) {
806 // Outlined helpers called by the EH runtime need to know the offset of the EH
807 // registration in order to recover the parent frame pointer. Now that we know
808 // we've code generated the parent, we can emit the label assignment that
809 // those helpers use to get the offset of the registration node.
810 assert(FuncInfo.EHRegNodeEscapeIndex != INT_MAX &&
811 "no EH reg node localescape index");
812 MCSymbol *ParentFrameOffset =
813 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(FLinkageName);
814 MCSymbol *RegistrationOffsetSym = Asm->OutContext.getOrCreateFrameAllocSymbol(
815 FLinkageName, FuncInfo.EHRegNodeEscapeIndex);
816 const MCExpr *RegistrationOffsetSymRef =
817 MCSymbolRefExpr::create(RegistrationOffsetSym, Asm->OutContext);
818 Asm->OutStreamer->EmitAssignment(ParentFrameOffset, RegistrationOffsetSymRef);
821 /// Emit the language-specific data that _except_handler3 and 4 expect. This is
822 /// functionally equivalent to the __C_specific_handler table, except it is
823 /// indexed by state number instead of IP.
824 void WinException::emitExceptHandlerTable(const MachineFunction *MF) {
825 MCStreamer &OS = *Asm->OutStreamer;
826 const Function *F = MF->getFunction();
827 StringRef FLinkageName = GlobalValue::getRealLinkageName(F->getName());
829 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
830 emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
832 // Emit the __ehtable label that we use for llvm.x86.seh.lsda.
833 MCSymbol *LSDALabel = Asm->OutContext.getOrCreateLSDASymbol(FLinkageName);
834 OS.EmitValueToAlignment(4);
835 OS.EmitLabel(LSDALabel);
837 const Function *Per =
838 dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
839 StringRef PerName = Per->getName();
841 if (PerName == "_except_handler4") {
842 // The LSDA for _except_handler4 starts with this struct, followed by the
845 // struct EH4ScopeTable {
846 // int32_t GSCookieOffset;
847 // int32_t GSCookieXOROffset;
848 // int32_t EHCookieOffset;
849 // int32_t EHCookieXOROffset;
850 // ScopeTableEntry ScopeRecord[];
853 // Only the EHCookieOffset field appears to vary, and it appears to be the
854 // offset from the final saved SP value to the retaddr.
855 OS.EmitIntValue(-2, 4);
856 OS.EmitIntValue(0, 4);
858 OS.EmitIntValue(9999, 4);
859 OS.EmitIntValue(0, 4);
863 if (!FuncInfo.SEHUnwindMap.empty()) {
864 for (SEHUnwindMapEntry &UME : FuncInfo.SEHUnwindMap) {
865 MCSymbol *ExceptOrFinally =
866 UME.Handler.get<MachineBasicBlock *>()->getSymbol();
867 OS.EmitIntValue(UME.ToState, 4); // ToState
868 OS.EmitValue(create32bitRef(UME.Filter), 4); // Filter
869 OS.EmitValue(create32bitRef(ExceptOrFinally), 4); // Except/Finally
873 // FIXME: The following code is for the old landingpad-based SEH
874 // implementation. Remove it when possible.
876 // Build a list of pointers to LandingPadInfos and then sort by WinEHState.
877 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
878 SmallVector<const LandingPadInfo *, 4> LPads;
879 LPads.reserve((PadInfos.size()));
880 for (const LandingPadInfo &LPInfo : PadInfos)
881 LPads.push_back(&LPInfo);
882 std::sort(LPads.begin(), LPads.end(),
883 [](const LandingPadInfo *L, const LandingPadInfo *R) {
884 return L->WinEHState < R->WinEHState;
887 // For each action in each lpad, emit one of these:
888 // struct ScopeTableEntry {
889 // int32_t EnclosingLevel;
890 // int32_t (__cdecl *Filter)();
891 // void *HandlerOrFinally;
894 // The "outermost" action will use BaseState as its enclosing level. Each
895 // other action will refer to the previous state as its enclosing level.
897 for (const LandingPadInfo *LPInfo : LPads) {
898 int EnclosingLevel = BaseState;
899 assert(CurState + int(LPInfo->SEHHandlers.size()) - 1 ==
900 LPInfo->WinEHState &&
901 "gaps in the SEH scope table");
902 for (auto I = LPInfo->SEHHandlers.rbegin(), E = LPInfo->SEHHandlers.rend();
904 const SEHHandler &Handler = *I;
905 const BlockAddress *BA = Handler.RecoverBA;
906 const Function *F = Handler.FilterOrFinally;
907 assert(F && "cannot catch all in 32-bit SEH without filter function");
908 const MCExpr *FilterOrNull =
909 create32bitRef(BA ? Asm->getSymbol(F) : nullptr);
910 const MCExpr *ExceptOrFinally = create32bitRef(
911 BA ? Asm->GetBlockAddressSymbol(BA) : Asm->getSymbol(F));
913 OS.EmitIntValue(EnclosingLevel, 4);
914 OS.EmitValue(FilterOrNull, 4);
915 OS.EmitValue(ExceptOrFinally, 4);
917 // The next state unwinds to this state.
918 EnclosingLevel = CurState;