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"
41 #include "llvm/Target/TargetSubtargetInfo.h"
44 WinException::WinException(AsmPrinter *A) : EHStreamer(A) {
45 // MSVC's EH tables are always composed of 32-bit words. All known 64-bit
46 // platforms use an imagerel32 relocation to refer to symbols.
47 useImageRel32 = (A->getDataLayout().getPointerSizeInBits() == 64);
50 WinException::~WinException() {}
52 /// endModule - Emit all exception information that should come after the
54 void WinException::endModule() {
55 auto &OS = *Asm->OutStreamer;
56 const Module *M = MMI->getModule();
57 for (const Function &F : *M)
58 if (F.hasFnAttribute("safeseh"))
59 OS.EmitCOFFSafeSEH(Asm->getSymbol(&F));
62 void WinException::beginFunction(const MachineFunction *MF) {
63 shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
65 // If any landing pads survive, we need an EH table.
66 bool hasLandingPads = !MMI->getLandingPads().empty();
67 bool hasEHFunclets = MMI->hasEHFunclets();
69 const Function *F = MF->getFunction();
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 if (!Asm->MAI->usesWindowsCFI()) {
94 shouldEmitLSDA = hasEHFunclets;
95 shouldEmitPersonality = false;
99 beginFunclet(MF->front(), Asm->CurrentFnSym);
102 /// endFunction - Gather and emit post-function exception information.
104 void WinException::endFunction(const MachineFunction *MF) {
105 if (!shouldEmitPersonality && !shouldEmitMoves && !shouldEmitLSDA)
108 const Function *F = MF->getFunction();
109 EHPersonality Per = EHPersonality::Unknown;
110 if (F->hasPersonalityFn())
111 Per = classifyEHPersonality(F->getPersonalityFn());
113 // Get rid of any dead landing pads if we're not using funclets. In funclet
114 // schemes, the landing pad is not actually reachable. It only exists so
115 // that we can emit the right table data.
116 if (!isFuncletEHPersonality(Per))
117 MMI->TidyLandingPads();
121 // endFunclet will emit the necessary .xdata tables for x64 SEH.
122 if (Per == EHPersonality::MSVC_Win64SEH && MMI->hasEHFunclets())
125 if (shouldEmitPersonality || shouldEmitLSDA) {
126 Asm->OutStreamer->PushSection();
128 // Just switch sections to the right xdata section. This use of CurrentFnSym
129 // assumes that we only emit the LSDA when ending the parent function.
130 MCSection *XData = WinEH::UnwindEmitter::getXDataSection(Asm->CurrentFnSym,
132 Asm->OutStreamer->SwitchSection(XData);
134 // Emit the tables appropriate to the personality function in use. If we
135 // don't recognize the personality, assume it uses an Itanium-style LSDA.
136 if (Per == EHPersonality::MSVC_Win64SEH)
137 emitCSpecificHandlerTable(MF);
138 else if (Per == EHPersonality::MSVC_X86SEH)
139 emitExceptHandlerTable(MF);
140 else if (Per == EHPersonality::MSVC_CXX)
141 emitCXXFrameHandler3Table(MF);
142 else if (Per == EHPersonality::CoreCLR)
143 emitCLRExceptionTable(MF);
145 emitExceptionTable();
147 Asm->OutStreamer->PopSection();
151 /// Retreive the MCSymbol for a GlobalValue or MachineBasicBlock.
152 static MCSymbol *getMCSymbolForMBB(AsmPrinter *Asm,
153 const MachineBasicBlock *MBB) {
157 assert(MBB->isEHFuncletEntry());
159 // Give catches and cleanups a name based off of their parent function and
160 // their funclet entry block's number.
161 const MachineFunction *MF = MBB->getParent();
162 const Function *F = MF->getFunction();
163 StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
164 MCContext &Ctx = MF->getContext();
165 StringRef HandlerPrefix = MBB->isCleanupFuncletEntry() ? "dtor" : "catch";
166 return Ctx.getOrCreateSymbol("?" + HandlerPrefix + "$" +
167 Twine(MBB->getNumber()) + "@?0?" +
168 FuncLinkageName + "@4HA");
171 void WinException::beginFunclet(const MachineBasicBlock &MBB,
173 CurrentFuncletEntry = &MBB;
175 const Function *F = Asm->MF->getFunction();
176 // If a symbol was not provided for the funclet, invent one.
178 Sym = getMCSymbolForMBB(Asm, &MBB);
180 // Describe our funclet symbol as a function with internal linkage.
181 Asm->OutStreamer->BeginCOFFSymbolDef(Sym);
182 Asm->OutStreamer->EmitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC);
183 Asm->OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
184 << COFF::SCT_COMPLEX_TYPE_SHIFT);
185 Asm->OutStreamer->EndCOFFSymbolDef();
187 // We want our funclet's entry point to be aligned such that no nops will be
188 // present after the label.
189 Asm->EmitAlignment(std::max(Asm->MF->getAlignment(), MBB.getAlignment()),
192 // Now that we've emitted the alignment directive, point at our funclet.
193 Asm->OutStreamer->EmitLabel(Sym);
196 // Mark 'Sym' as starting our funclet.
197 if (shouldEmitMoves || shouldEmitPersonality)
198 Asm->OutStreamer->EmitWinCFIStartProc(Sym);
200 if (shouldEmitPersonality) {
201 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
202 const Function *PerFn = nullptr;
204 // Determine which personality routine we are using for this funclet.
205 if (F->hasPersonalityFn())
206 PerFn = dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
207 const MCSymbol *PersHandlerSym =
208 TLOF.getCFIPersonalitySymbol(PerFn, *Asm->Mang, Asm->TM, MMI);
210 // Classify the personality routine so that we may reason about it.
211 EHPersonality Per = EHPersonality::Unknown;
212 if (F->hasPersonalityFn())
213 Per = classifyEHPersonality(F->getPersonalityFn());
215 // Do not emit a .seh_handler directive if it is a C++ cleanup funclet.
216 if (Per != EHPersonality::MSVC_CXX ||
217 !CurrentFuncletEntry->isCleanupFuncletEntry())
218 Asm->OutStreamer->EmitWinEHHandler(PersHandlerSym, true, true);
222 void WinException::endFunclet() {
223 // No funclet to process? Great, we have nothing to do.
224 if (!CurrentFuncletEntry)
227 if (shouldEmitMoves || shouldEmitPersonality) {
228 const Function *F = Asm->MF->getFunction();
229 EHPersonality Per = EHPersonality::Unknown;
230 if (F->hasPersonalityFn())
231 Per = classifyEHPersonality(F->getPersonalityFn());
233 // The .seh_handlerdata directive implicitly switches section, push the
234 // current section so that we may return to it.
235 Asm->OutStreamer->PushSection();
237 // Emit an UNWIND_INFO struct describing the prologue.
238 Asm->OutStreamer->EmitWinEHHandlerData();
240 if (Per == EHPersonality::MSVC_CXX && shouldEmitPersonality &&
241 !CurrentFuncletEntry->isCleanupFuncletEntry()) {
242 // If this is a C++ catch funclet (or the parent function),
243 // emit a reference to the LSDA for the parent function.
244 StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
245 MCSymbol *FuncInfoXData = Asm->OutContext.getOrCreateSymbol(
246 Twine("$cppxdata$", FuncLinkageName));
247 Asm->OutStreamer->EmitValue(create32bitRef(FuncInfoXData), 4);
248 } else if (Per == EHPersonality::MSVC_Win64SEH && MMI->hasEHFunclets() &&
249 !CurrentFuncletEntry->isEHFuncletEntry()) {
250 // If this is the parent function in Win64 SEH, emit the LSDA immediately
251 // following .seh_handlerdata.
252 emitCSpecificHandlerTable(Asm->MF);
255 // Switch back to the previous section now that we are done writing to
257 Asm->OutStreamer->PopSection();
259 // Emit a .seh_endproc directive to mark the end of the function.
260 Asm->OutStreamer->EmitWinCFIEndProc();
263 // Let's make sure we don't try to end the same funclet twice.
264 CurrentFuncletEntry = nullptr;
267 const MCExpr *WinException::create32bitRef(const MCSymbol *Value) {
269 return MCConstantExpr::create(0, Asm->OutContext);
270 return MCSymbolRefExpr::create(Value, useImageRel32
271 ? MCSymbolRefExpr::VK_COFF_IMGREL32
272 : MCSymbolRefExpr::VK_None,
276 const MCExpr *WinException::create32bitRef(const Value *V) {
278 return MCConstantExpr::create(0, Asm->OutContext);
279 if (const auto *GV = dyn_cast<GlobalValue>(V))
280 return create32bitRef(Asm->getSymbol(GV));
281 return create32bitRef(MMI->getAddrLabelSymbol(cast<BasicBlock>(V)));
284 const MCExpr *WinException::getLabelPlusOne(const MCSymbol *Label) {
285 return MCBinaryExpr::createAdd(create32bitRef(Label),
286 MCConstantExpr::create(1, Asm->OutContext),
290 const MCExpr *WinException::getOffset(const MCSymbol *OffsetOf,
291 const MCSymbol *OffsetFrom) {
292 return MCBinaryExpr::createSub(
293 MCSymbolRefExpr::create(OffsetOf, Asm->OutContext),
294 MCSymbolRefExpr::create(OffsetFrom, Asm->OutContext), Asm->OutContext);
297 const MCExpr *WinException::getOffsetPlusOne(const MCSymbol *OffsetOf,
298 const MCSymbol *OffsetFrom) {
299 return MCBinaryExpr::createAdd(getOffset(OffsetOf, OffsetFrom),
300 MCConstantExpr::create(1, Asm->OutContext),
304 int WinException::getFrameIndexOffset(int FrameIndex) {
305 const TargetFrameLowering &TFI = *Asm->MF->getSubtarget().getFrameLowering();
307 if (Asm->MAI->usesWindowsCFI())
308 return TFI.getFrameIndexReferenceFromSP(*Asm->MF, FrameIndex, UnusedReg);
309 return TFI.getFrameIndexReference(*Asm->MF, FrameIndex, UnusedReg);
314 /// Top-level state used to represent unwind to caller
315 const int NullState = -1;
317 struct InvokeStateChange {
318 /// EH Label immediately after the last invoke in the previous state, or
319 /// nullptr if the previous state was the null state.
320 const MCSymbol *PreviousEndLabel;
322 /// EH label immediately before the first invoke in the new state, or nullptr
323 /// if the new state is the null state.
324 const MCSymbol *NewStartLabel;
326 /// State of the invoke following NewStartLabel, or NullState to indicate
327 /// the presence of calls which may unwind to caller.
331 /// Iterator that reports all the invoke state changes in a range of machine
332 /// basic blocks. Changes to the null state are reported whenever a call that
333 /// may unwind to caller is encountered. The MBB range is expected to be an
334 /// entire function or funclet, and the start and end of the range are treated
335 /// as being in the NullState even if there's not an unwind-to-caller call
336 /// before the first invoke or after the last one (i.e., the first state change
337 /// reported is the first change to something other than NullState, and a
338 /// change back to NullState is always reported at the end of iteration).
339 class InvokeStateChangeIterator {
340 InvokeStateChangeIterator(WinEHFuncInfo &EHInfo,
341 MachineFunction::const_iterator MFI,
342 MachineFunction::const_iterator MFE,
343 MachineBasicBlock::const_iterator MBBI)
344 : EHInfo(EHInfo), MFI(MFI), MFE(MFE), MBBI(MBBI) {
345 LastStateChange.PreviousEndLabel = nullptr;
346 LastStateChange.NewStartLabel = nullptr;
347 LastStateChange.NewState = NullState;
352 static iterator_range<InvokeStateChangeIterator>
353 range(WinEHFuncInfo &EHInfo, const MachineFunction &MF) {
354 // Reject empty MFs to simplify bookkeeping by ensuring that we can get the
355 // end of the last block.
357 auto FuncBegin = MF.begin();
358 auto FuncEnd = MF.end();
359 auto BlockBegin = FuncBegin->begin();
360 auto BlockEnd = MF.back().end();
362 InvokeStateChangeIterator(EHInfo, FuncBegin, FuncEnd, BlockBegin),
363 InvokeStateChangeIterator(EHInfo, FuncEnd, FuncEnd, BlockEnd));
365 static iterator_range<InvokeStateChangeIterator>
366 range(WinEHFuncInfo &EHInfo, MachineFunction::const_iterator Begin,
367 MachineFunction::const_iterator End) {
368 // Reject empty ranges to simplify bookkeeping by ensuring that we can get
369 // the end of the last block.
370 assert(Begin != End);
371 auto BlockBegin = Begin->begin();
372 auto BlockEnd = std::prev(End)->end();
373 return make_range(InvokeStateChangeIterator(EHInfo, Begin, End, BlockBegin),
374 InvokeStateChangeIterator(EHInfo, End, End, BlockEnd));
378 bool operator==(const InvokeStateChangeIterator &O) const {
379 // Must be visiting same block.
382 // Must be visiting same isntr.
385 // At end of block/instr iteration, we can still have two distinct states:
386 // one to report the final EndLabel, and another indicating the end of the
387 // state change iteration. Check for CurrentEndLabel equality to
388 // distinguish these.
389 return CurrentEndLabel == O.CurrentEndLabel;
392 bool operator!=(const InvokeStateChangeIterator &O) const {
393 return !operator==(O);
395 InvokeStateChange &operator*() { return LastStateChange; }
396 InvokeStateChange *operator->() { return &LastStateChange; }
397 InvokeStateChangeIterator &operator++() { return scan(); }
400 InvokeStateChangeIterator &scan();
402 WinEHFuncInfo &EHInfo;
403 const MCSymbol *CurrentEndLabel = nullptr;
404 MachineFunction::const_iterator MFI;
405 MachineFunction::const_iterator MFE;
406 MachineBasicBlock::const_iterator MBBI;
407 InvokeStateChange LastStateChange;
408 bool VisitingInvoke = false;
411 } // end anonymous namespace
413 InvokeStateChangeIterator &InvokeStateChangeIterator::scan() {
414 bool IsNewBlock = false;
415 for (; MFI != MFE; ++MFI, IsNewBlock = true) {
418 for (auto MBBE = MFI->end(); MBBI != MBBE; ++MBBI) {
419 const MachineInstr &MI = *MBBI;
420 if (!VisitingInvoke && LastStateChange.NewState != NullState &&
421 MI.isCall() && !EHStreamer::callToNoUnwindFunction(&MI)) {
422 // Indicate a change of state to the null state. We don't have
423 // start/end EH labels handy but the caller won't expect them for
424 // null state regions.
425 LastStateChange.PreviousEndLabel = CurrentEndLabel;
426 LastStateChange.NewStartLabel = nullptr;
427 LastStateChange.NewState = NullState;
428 CurrentEndLabel = nullptr;
429 // Don't re-visit this instr on the next scan
434 // All other state changes are at EH labels before/after invokes.
437 MCSymbol *Label = MI.getOperand(0).getMCSymbol();
438 if (Label == CurrentEndLabel) {
439 VisitingInvoke = false;
442 auto InvokeMapIter = EHInfo.InvokeToStateMap.find(Label);
443 // Ignore EH labels that aren't the ones inserted before an invoke
444 if (InvokeMapIter == EHInfo.InvokeToStateMap.end())
446 auto &StateAndEnd = InvokeMapIter->second;
447 int NewState = StateAndEnd.first;
448 // Ignore EH labels explicitly annotated with the null state (which
449 // can happen for invokes that unwind to a chain of endpads the last
450 // of which unwinds to caller). We'll see the subsequent invoke and
451 // report a transition to the null state same as we do for calls.
452 if (NewState == NullState)
454 // Keep track of the fact that we're between EH start/end labels so
455 // we know not to treat the inoke we'll see as unwinding to caller.
456 VisitingInvoke = true;
457 if (NewState == LastStateChange.NewState) {
458 // The state isn't actually changing here. Record the new end and
460 CurrentEndLabel = StateAndEnd.second;
463 // Found a state change to report
464 LastStateChange.PreviousEndLabel = CurrentEndLabel;
465 LastStateChange.NewStartLabel = Label;
466 LastStateChange.NewState = NewState;
467 // Start keeping track of the new current end
468 CurrentEndLabel = StateAndEnd.second;
469 // Don't re-visit this instr on the next scan
474 // Iteration hit the end of the block range.
475 if (LastStateChange.NewState != NullState) {
476 // Report the end of the last new state
477 LastStateChange.PreviousEndLabel = CurrentEndLabel;
478 LastStateChange.NewStartLabel = nullptr;
479 LastStateChange.NewState = NullState;
480 // Leave CurrentEndLabel non-null to distinguish this state from end.
481 assert(CurrentEndLabel != nullptr);
484 // We've reported all state changes and hit the end state.
485 CurrentEndLabel = nullptr;
489 /// Emit the language-specific data that __C_specific_handler expects. This
490 /// handler lives in the x64 Microsoft C runtime and allows catching or cleaning
491 /// up after faults with __try, __except, and __finally. The typeinfo values
492 /// are not really RTTI data, but pointers to filter functions that return an
493 /// integer (1, 0, or -1) indicating how to handle the exception. For __finally
494 /// blocks and other cleanups, the landing pad label is zero, and the filter
495 /// function is actually a cleanup handler with the same prototype. A catch-all
496 /// entry is modeled with a null filter function field and a non-zero landing
499 /// Possible filter function return values:
500 /// EXCEPTION_EXECUTE_HANDLER (1):
501 /// Jump to the landing pad label after cleanups.
502 /// EXCEPTION_CONTINUE_SEARCH (0):
503 /// Continue searching this table or continue unwinding.
504 /// EXCEPTION_CONTINUE_EXECUTION (-1):
505 /// Resume execution at the trapping PC.
507 /// Inferred table structure:
511 /// imagerel32 LabelStart;
512 /// imagerel32 LabelEnd;
513 /// imagerel32 FilterOrFinally; // One means catch-all.
514 /// imagerel32 LabelLPad; // Zero means __finally.
515 /// } Entries[NumEntries];
517 void WinException::emitCSpecificHandlerTable(const MachineFunction *MF) {
518 auto &OS = *Asm->OutStreamer;
519 MCContext &Ctx = Asm->OutContext;
521 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(MF->getFunction());
522 // Use the assembler to compute the number of table entries through label
523 // difference and division.
524 MCSymbol *TableBegin =
525 Ctx.createTempSymbol("lsda_begin", /*AlwaysAddSuffix=*/true);
527 Ctx.createTempSymbol("lsda_end", /*AlwaysAddSuffix=*/true);
528 const MCExpr *LabelDiff = getOffset(TableEnd, TableBegin);
529 const MCExpr *EntrySize = MCConstantExpr::create(16, Ctx);
530 const MCExpr *EntryCount = MCBinaryExpr::createDiv(LabelDiff, EntrySize, Ctx);
531 OS.EmitValue(EntryCount, 4);
533 OS.EmitLabel(TableBegin);
535 // Iterate over all the invoke try ranges. Unlike MSVC, LLVM currently only
536 // models exceptions from invokes. LLVM also allows arbitrary reordering of
537 // the code, so our tables end up looking a bit different. Rather than
538 // trying to match MSVC's tables exactly, we emit a denormalized table. For
539 // each range of invokes in the same state, we emit table entries for all
540 // the actions that would be taken in that state. This means our tables are
541 // slightly bigger, which is OK.
542 const MCSymbol *LastStartLabel = nullptr;
543 int LastEHState = -1;
544 // Break out before we enter into a finally funclet.
545 // FIXME: We need to emit separate EH tables for cleanups.
546 MachineFunction::const_iterator End = MF->end();
547 MachineFunction::const_iterator Stop = std::next(MF->begin());
548 while (Stop != End && !Stop->isEHFuncletEntry())
550 for (const auto &StateChange :
551 InvokeStateChangeIterator::range(FuncInfo, MF->begin(), Stop)) {
552 // Emit all the actions for the state we just transitioned out of
553 // if it was not the null state
554 if (LastEHState != -1)
555 emitSEHActionsForRange(FuncInfo, LastStartLabel,
556 StateChange.PreviousEndLabel, LastEHState);
557 LastStartLabel = StateChange.NewStartLabel;
558 LastEHState = StateChange.NewState;
561 OS.EmitLabel(TableEnd);
564 void WinException::emitSEHActionsForRange(WinEHFuncInfo &FuncInfo,
565 const MCSymbol *BeginLabel,
566 const MCSymbol *EndLabel, int State) {
567 auto &OS = *Asm->OutStreamer;
568 MCContext &Ctx = Asm->OutContext;
570 assert(BeginLabel && EndLabel);
571 while (State != -1) {
572 SEHUnwindMapEntry &UME = FuncInfo.SEHUnwindMap[State];
573 const MCExpr *FilterOrFinally;
574 const MCExpr *ExceptOrNull;
575 auto *Handler = UME.Handler.get<MachineBasicBlock *>();
577 FilterOrFinally = create32bitRef(getMCSymbolForMBB(Asm, Handler));
578 ExceptOrNull = MCConstantExpr::create(0, Ctx);
580 // For an except, the filter can be 1 (catch-all) or a function
582 FilterOrFinally = UME.Filter ? create32bitRef(UME.Filter)
583 : MCConstantExpr::create(1, Ctx);
584 ExceptOrNull = create32bitRef(Handler->getSymbol());
587 OS.EmitValue(getLabelPlusOne(BeginLabel), 4);
588 OS.EmitValue(getLabelPlusOne(EndLabel), 4);
589 OS.EmitValue(FilterOrFinally, 4);
590 OS.EmitValue(ExceptOrNull, 4);
592 assert(UME.ToState < State && "states should decrease");
597 void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
598 const Function *F = MF->getFunction();
599 auto &OS = *Asm->OutStreamer;
600 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
602 StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
604 SmallVector<std::pair<const MCExpr *, int>, 4> IPToStateTable;
605 MCSymbol *FuncInfoXData = nullptr;
606 if (shouldEmitPersonality) {
607 // If we're 64-bit, emit a pointer to the C++ EH data, and build a map from
608 // IPs to state numbers.
610 Asm->OutContext.getOrCreateSymbol(Twine("$cppxdata$", FuncLinkageName));
611 computeIP2StateTable(MF, FuncInfo, IPToStateTable);
613 FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(FuncLinkageName);
614 emitEHRegistrationOffsetLabel(FuncInfo, FuncLinkageName);
617 int UnwindHelpOffset = 0;
618 if (Asm->MAI->usesWindowsCFI())
619 UnwindHelpOffset = getFrameIndexOffset(FuncInfo.UnwindHelpFrameIdx);
621 MCSymbol *UnwindMapXData = nullptr;
622 MCSymbol *TryBlockMapXData = nullptr;
623 MCSymbol *IPToStateXData = nullptr;
624 if (!FuncInfo.CxxUnwindMap.empty())
625 UnwindMapXData = Asm->OutContext.getOrCreateSymbol(
626 Twine("$stateUnwindMap$", FuncLinkageName));
627 if (!FuncInfo.TryBlockMap.empty())
629 Asm->OutContext.getOrCreateSymbol(Twine("$tryMap$", FuncLinkageName));
630 if (!IPToStateTable.empty())
632 Asm->OutContext.getOrCreateSymbol(Twine("$ip2state$", FuncLinkageName));
635 // uint32_t MagicNumber
637 // UnwindMapEntry *UnwindMap;
638 // uint32_t NumTryBlocks;
639 // TryBlockMapEntry *TryBlockMap;
640 // uint32_t IPMapEntries; // always 0 for x86
641 // IPToStateMapEntry *IPToStateMap; // always 0 for x86
642 // uint32_t UnwindHelp; // non-x86 only
643 // ESTypeList *ESTypeList;
646 // EHFlags & 1 -> Synchronous exceptions only, no async exceptions.
647 // EHFlags & 2 -> ???
648 // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue.
649 OS.EmitValueToAlignment(4);
650 OS.EmitLabel(FuncInfoXData);
651 OS.EmitIntValue(0x19930522, 4); // MagicNumber
652 OS.EmitIntValue(FuncInfo.CxxUnwindMap.size(), 4); // MaxState
653 OS.EmitValue(create32bitRef(UnwindMapXData), 4); // UnwindMap
654 OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4); // NumTryBlocks
655 OS.EmitValue(create32bitRef(TryBlockMapXData), 4); // TryBlockMap
656 OS.EmitIntValue(IPToStateTable.size(), 4); // IPMapEntries
657 OS.EmitValue(create32bitRef(IPToStateXData), 4); // IPToStateMap
658 if (Asm->MAI->usesWindowsCFI())
659 OS.EmitIntValue(UnwindHelpOffset, 4); // UnwindHelp
660 OS.EmitIntValue(0, 4); // ESTypeList
661 OS.EmitIntValue(1, 4); // EHFlags
667 if (UnwindMapXData) {
668 OS.EmitLabel(UnwindMapXData);
669 for (const CxxUnwindMapEntry &UME : FuncInfo.CxxUnwindMap) {
670 MCSymbol *CleanupSym =
671 getMCSymbolForMBB(Asm, UME.Cleanup.dyn_cast<MachineBasicBlock *>());
672 OS.EmitIntValue(UME.ToState, 4); // ToState
673 OS.EmitValue(create32bitRef(CleanupSym), 4); // Action
680 // int32_t CatchHigh;
681 // int32_t NumCatches;
682 // HandlerType *HandlerArray;
684 if (TryBlockMapXData) {
685 OS.EmitLabel(TryBlockMapXData);
686 SmallVector<MCSymbol *, 1> HandlerMaps;
687 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
688 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
690 MCSymbol *HandlerMapXData = nullptr;
691 if (!TBME.HandlerArray.empty())
693 Asm->OutContext.getOrCreateSymbol(Twine("$handlerMap$")
696 .concat(FuncLinkageName));
697 HandlerMaps.push_back(HandlerMapXData);
699 // TBMEs should form intervals.
700 assert(0 <= TBME.TryLow && "bad trymap interval");
701 assert(TBME.TryLow <= TBME.TryHigh && "bad trymap interval");
702 assert(TBME.TryHigh < TBME.CatchHigh && "bad trymap interval");
703 assert(TBME.CatchHigh < int(FuncInfo.CxxUnwindMap.size()) &&
704 "bad trymap interval");
706 OS.EmitIntValue(TBME.TryLow, 4); // TryLow
707 OS.EmitIntValue(TBME.TryHigh, 4); // TryHigh
708 OS.EmitIntValue(TBME.CatchHigh, 4); // CatchHigh
709 OS.EmitIntValue(TBME.HandlerArray.size(), 4); // NumCatches
710 OS.EmitValue(create32bitRef(HandlerMapXData), 4); // HandlerArray
713 // All funclets use the same parent frame offset currently.
714 unsigned ParentFrameOffset = 0;
715 if (shouldEmitPersonality) {
716 const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
717 ParentFrameOffset = TFI->getWinEHParentFrameOffset(*MF);
720 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
721 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
722 MCSymbol *HandlerMapXData = HandlerMaps[I];
723 if (!HandlerMapXData)
726 // int32_t Adjectives;
727 // TypeDescriptor *Type;
728 // int32_t CatchObjOffset;
729 // void (*Handler)();
730 // int32_t ParentFrameOffset; // x64 only
732 OS.EmitLabel(HandlerMapXData);
733 for (const WinEHHandlerType &HT : TBME.HandlerArray) {
734 // Get the frame escape label with the offset of the catch object. If
735 // the index is INT_MAX, then there is no catch object, and we should
736 // emit an offset of zero, indicating that no copy will occur.
737 const MCExpr *FrameAllocOffsetRef = nullptr;
738 if (HT.CatchObj.FrameIndex != INT_MAX) {
739 int Offset = getFrameIndexOffset(HT.CatchObj.FrameIndex);
740 // For 32-bit, the catch object offset is relative to the end of the
741 // EH registration node. For 64-bit, it's relative to SP at the end of
743 if (!shouldEmitPersonality) {
744 assert(FuncInfo.EHRegNodeEndOffset != INT_MAX);
745 Offset += FuncInfo.EHRegNodeEndOffset;
747 FrameAllocOffsetRef = MCConstantExpr::create(Offset, Asm->OutContext);
749 FrameAllocOffsetRef = MCConstantExpr::create(0, Asm->OutContext);
752 MCSymbol *HandlerSym =
753 getMCSymbolForMBB(Asm, HT.Handler.dyn_cast<MachineBasicBlock *>());
755 OS.EmitIntValue(HT.Adjectives, 4); // Adjectives
756 OS.EmitValue(create32bitRef(HT.TypeDescriptor), 4); // Type
757 OS.EmitValue(FrameAllocOffsetRef, 4); // CatchObjOffset
758 OS.EmitValue(create32bitRef(HandlerSym), 4); // Handler
759 if (shouldEmitPersonality)
760 OS.EmitIntValue(ParentFrameOffset, 4); // ParentFrameOffset
765 // IPToStateMapEntry {
769 if (IPToStateXData) {
770 OS.EmitLabel(IPToStateXData);
771 for (auto &IPStatePair : IPToStateTable) {
772 OS.EmitValue(IPStatePair.first, 4); // IP
773 OS.EmitIntValue(IPStatePair.second, 4); // State
778 void WinException::computeIP2StateTable(
779 const MachineFunction *MF, WinEHFuncInfo &FuncInfo,
780 SmallVectorImpl<std::pair<const MCExpr *, int>> &IPToStateTable) {
781 // Indicate that all calls from the prologue to the first invoke unwind to
782 // caller. We handle this as a special case since other ranges starting at end
783 // labels need to use LtmpN+1.
784 MCSymbol *StartLabel = Asm->getFunctionBegin();
785 assert(StartLabel && "need local function start label");
786 IPToStateTable.push_back(std::make_pair(create32bitRef(StartLabel), -1));
788 // FIXME: Do we need to emit entries for funclet base states?
789 for (const auto &StateChange :
790 InvokeStateChangeIterator::range(FuncInfo, *MF)) {
791 // Compute the label to report as the start of this entry; use the EH start
792 // label for the invoke if we have one, otherwise (this is a call which may
793 // unwind to our caller and does not have an EH start label, so) use the
794 // previous end label.
795 const MCSymbol *ChangeLabel = StateChange.NewStartLabel;
797 ChangeLabel = StateChange.PreviousEndLabel;
798 // Emit an entry indicating that PCs after 'Label' have this EH state.
799 IPToStateTable.push_back(
800 std::make_pair(getLabelPlusOne(ChangeLabel), StateChange.NewState));
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 assert(!FuncInfo.SEHUnwindMap.empty());
864 for (SEHUnwindMapEntry &UME : FuncInfo.SEHUnwindMap) {
865 MCSymbol *ExceptOrFinally =
866 UME.Handler.get<MachineBasicBlock *>()->getSymbol();
867 // -1 is usually the base state for "unwind to caller", but for
868 // _except_handler4 it's -2. Do that replacement here if necessary.
869 int ToState = UME.ToState == -1 ? BaseState : UME.ToState;
870 OS.EmitIntValue(ToState, 4); // ToState
871 OS.EmitValue(create32bitRef(UME.Filter), 4); // Filter
872 OS.EmitValue(create32bitRef(ExceptOrFinally), 4); // Except/Finally
876 static int getRank(WinEHFuncInfo &FuncInfo, int State) {
878 while (State != -1) {
880 State = FuncInfo.ClrEHUnwindMap[State].Parent;
885 static int getAncestor(WinEHFuncInfo &FuncInfo, int Left, int Right) {
886 int LeftRank = getRank(FuncInfo, Left);
887 int RightRank = getRank(FuncInfo, Right);
889 while (LeftRank < RightRank) {
890 Right = FuncInfo.ClrEHUnwindMap[Right].Parent;
894 while (RightRank < LeftRank) {
895 Left = FuncInfo.ClrEHUnwindMap[Left].Parent;
899 while (Left != Right) {
900 Left = FuncInfo.ClrEHUnwindMap[Left].Parent;
901 Right = FuncInfo.ClrEHUnwindMap[Right].Parent;
907 void WinException::emitCLRExceptionTable(const MachineFunction *MF) {
908 // CLR EH "states" are really just IDs that identify handlers/funclets;
909 // states, handlers, and funclets all have 1:1 mappings between them, and a
910 // handler/funclet's "state" is its index in the ClrEHUnwindMap.
911 MCStreamer &OS = *Asm->OutStreamer;
912 const Function *F = MF->getFunction();
913 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
914 MCSymbol *FuncBeginSym = Asm->getFunctionBegin();
915 MCSymbol *FuncEndSym = Asm->getFunctionEnd();
917 // A ClrClause describes a protected region.
919 const MCSymbol *StartLabel; // Start of protected region
920 const MCSymbol *EndLabel; // End of protected region
921 int State; // Index of handler protecting the protected region
922 int EnclosingState; // Index of funclet enclosing the protected region
924 SmallVector<ClrClause, 8> Clauses;
926 // Build a map from handler MBBs to their corresponding states (i.e. their
927 // indices in the ClrEHUnwindMap).
928 int NumStates = FuncInfo.ClrEHUnwindMap.size();
929 assert(NumStates > 0 && "Don't need exception table!");
930 DenseMap<const MachineBasicBlock *, int> HandlerStates;
931 for (int State = 0; State < NumStates; ++State) {
932 MachineBasicBlock *HandlerBlock =
933 FuncInfo.ClrEHUnwindMap[State].Handler.get<MachineBasicBlock *>();
934 HandlerStates[HandlerBlock] = State;
935 // Use this loop through all handlers to verify our assumption (used in
936 // the MinEnclosingState computation) that ancestors have lower state
937 // numbers than their descendants.
938 assert(FuncInfo.ClrEHUnwindMap[State].Parent < State &&
939 "ill-formed state numbering");
941 // Map the main function to the NullState.
942 HandlerStates[MF->begin()] = NullState;
944 // Write out a sentinel indicating the end of the standard (Windows) xdata
945 // and the start of the additional (CLR) info.
946 OS.EmitIntValue(0xffffffff, 4);
947 // Write out the number of funclets
948 OS.EmitIntValue(NumStates, 4);
950 // Walk the machine blocks/instrs, computing and emitting a few things:
951 // 1. Emit a list of the offsets to each handler entry, in lexical order.
952 // 2. Compute a map (EndSymbolMap) from each funclet to the symbol at its end.
953 // 3. Compute the list of ClrClauses, in the required order (inner before
954 // outer, earlier before later; the order by which a forward scan with
955 // early termination will find the innermost enclosing clause covering
957 // 4. A map (MinClauseMap) from each handler index to the index of the
958 // outermost funclet/function which contains a try clause targeting the
959 // key handler. This will be used to determine IsDuplicate-ness when
960 // emitting ClrClauses. The NullState value is used to indicate that the
961 // top-level function contains a try clause targeting the key handler.
962 // HandlerStack is a stack of (PendingStartLabel, PendingState) pairs for
963 // try regions we entered before entering the PendingState try but which
964 // we haven't yet exited.
965 SmallVector<std::pair<const MCSymbol *, int>, 4> HandlerStack;
966 // EndSymbolMap and MinClauseMap are maps described above.
967 std::unique_ptr<MCSymbol *[]> EndSymbolMap(new MCSymbol *[NumStates]);
968 SmallVector<int, 4> MinClauseMap((size_t)NumStates, NumStates);
970 // Visit the root function and each funclet.
972 for (MachineFunction::const_iterator FuncletStart = MF->begin(),
973 FuncletEnd = MF->begin(),
975 FuncletStart != End; FuncletStart = FuncletEnd) {
976 int FuncletState = HandlerStates[FuncletStart];
977 // Find the end of the funclet
978 MCSymbol *EndSymbol = FuncEndSym;
979 while (++FuncletEnd != End) {
980 if (FuncletEnd->isEHFuncletEntry()) {
981 EndSymbol = getMCSymbolForMBB(Asm, FuncletEnd);
985 // Emit the function/funclet end and, if this is a funclet (and not the
986 // root function), record it in the EndSymbolMap.
987 OS.EmitValue(getOffset(EndSymbol, FuncBeginSym), 4);
988 if (FuncletState != NullState) {
989 // Record the end of the handler.
990 EndSymbolMap[FuncletState] = EndSymbol;
993 // Walk the state changes in this function/funclet and compute its clauses.
994 // Funclets always start in the null state.
995 const MCSymbol *CurrentStartLabel = nullptr;
996 int CurrentState = NullState;
997 assert(HandlerStack.empty());
998 for (const auto &StateChange :
999 InvokeStateChangeIterator::range(FuncInfo, FuncletStart, FuncletEnd)) {
1000 // Close any try regions we're not still under
1002 getAncestor(FuncInfo, CurrentState, StateChange.NewState);
1003 while (CurrentState != AncestorState) {
1004 assert(CurrentState != NullState && "Failed to find ancestor!");
1005 // Close the pending clause
1006 Clauses.push_back({CurrentStartLabel, StateChange.PreviousEndLabel,
1007 CurrentState, FuncletState});
1008 // Now the parent handler is current
1009 CurrentState = FuncInfo.ClrEHUnwindMap[CurrentState].Parent;
1010 // Pop the new start label from the handler stack if we've exited all
1011 // descendants of the corresponding handler.
1012 if (HandlerStack.back().second == CurrentState)
1013 CurrentStartLabel = HandlerStack.pop_back_val().first;
1016 if (StateChange.NewState != CurrentState) {
1017 // For each clause we're starting, update the MinClauseMap so we can
1018 // know which is the topmost funclet containing a clause targeting
1020 for (int EnteredState = StateChange.NewState;
1021 EnteredState != CurrentState;
1022 EnteredState = FuncInfo.ClrEHUnwindMap[EnteredState].Parent) {
1023 int &MinEnclosingState = MinClauseMap[EnteredState];
1024 if (FuncletState < MinEnclosingState)
1025 MinEnclosingState = FuncletState;
1027 // Save the previous current start/label on the stack and update to
1028 // the newly-current start/state.
1029 HandlerStack.emplace_back(CurrentStartLabel, CurrentState);
1030 CurrentStartLabel = StateChange.NewStartLabel;
1031 CurrentState = StateChange.NewState;
1034 assert(HandlerStack.empty());
1037 // Now emit the clause info, starting with the number of clauses.
1038 OS.EmitIntValue(Clauses.size(), 4);
1039 for (ClrClause &Clause : Clauses) {
1040 // Emit a CORINFO_EH_CLAUSE :
1042 struct CORINFO_EH_CLAUSE
1044 CORINFO_EH_CLAUSE_FLAGS Flags; // actually a CorExceptionFlag
1046 DWORD TryLength; // actually TryEndOffset
1047 DWORD HandlerOffset;
1048 DWORD HandlerLength; // actually HandlerEndOffset
1051 DWORD ClassToken; // use for catch clauses
1052 DWORD FilterOffset; // use for filter clauses
1056 enum CORINFO_EH_CLAUSE_FLAGS
1058 CORINFO_EH_CLAUSE_NONE = 0,
1059 CORINFO_EH_CLAUSE_FILTER = 0x0001, // This clause is for a filter
1060 CORINFO_EH_CLAUSE_FINALLY = 0x0002, // This clause is a finally clause
1061 CORINFO_EH_CLAUSE_FAULT = 0x0004, // This clause is a fault clause
1063 typedef enum CorExceptionFlag
1065 COR_ILEXCEPTION_CLAUSE_NONE,
1066 COR_ILEXCEPTION_CLAUSE_FILTER = 0x0001, // This is a filter clause
1067 COR_ILEXCEPTION_CLAUSE_FINALLY = 0x0002, // This is a finally clause
1068 COR_ILEXCEPTION_CLAUSE_FAULT = 0x0004, // This is a fault clause
1069 COR_ILEXCEPTION_CLAUSE_DUPLICATED = 0x0008, // duplicated clause. This
1070 // clause was duplicated
1071 // to a funclet which was
1072 // pulled out of line
1075 // Add 1 to the start/end of the EH clause; the IP associated with a
1076 // call when the runtime does its scan is the IP of the next instruction
1077 // (the one to which control will return after the call), so we need
1078 // to add 1 to the end of the clause to cover that offset. We also add
1079 // 1 to the start of the clause to make sure that the ranges reported
1080 // for all clauses are disjoint. Note that we'll need some additional
1081 // logic when machine traps are supported, since in that case the IP
1082 // that the runtime uses is the offset of the faulting instruction
1083 // itself; if such an instruction immediately follows a call but the
1084 // two belong to different clauses, we'll need to insert a nop between
1085 // them so the runtime can distinguish the point to which the call will
1086 // return from the point at which the fault occurs.
1088 const MCExpr *ClauseBegin =
1089 getOffsetPlusOne(Clause.StartLabel, FuncBeginSym);
1090 const MCExpr *ClauseEnd = getOffsetPlusOne(Clause.EndLabel, FuncBeginSym);
1092 ClrEHUnwindMapEntry &Entry = FuncInfo.ClrEHUnwindMap[Clause.State];
1093 MachineBasicBlock *HandlerBlock = Entry.Handler.get<MachineBasicBlock *>();
1094 MCSymbol *BeginSym = getMCSymbolForMBB(Asm, HandlerBlock);
1095 const MCExpr *HandlerBegin = getOffset(BeginSym, FuncBeginSym);
1096 MCSymbol *EndSym = EndSymbolMap[Clause.State];
1097 const MCExpr *HandlerEnd = getOffset(EndSym, FuncBeginSym);
1100 switch (Entry.HandlerType) {
1101 case ClrHandlerType::Catch:
1102 // Leaving bits 0-2 clear indicates catch.
1104 case ClrHandlerType::Filter:
1107 case ClrHandlerType::Finally:
1110 case ClrHandlerType::Fault:
1114 if (Clause.EnclosingState != MinClauseMap[Clause.State]) {
1115 // This is a "duplicate" clause; the handler needs to be entered from a
1116 // frame above the one holding the invoke.
1117 assert(Clause.EnclosingState > MinClauseMap[Clause.State]);
1120 OS.EmitIntValue(Flags, 4);
1122 // Write the clause start/end
1123 OS.EmitValue(ClauseBegin, 4);
1124 OS.EmitValue(ClauseEnd, 4);
1126 // Write out the handler start/end
1127 OS.EmitValue(HandlerBegin, 4);
1128 OS.EmitValue(HandlerEnd, 4);
1130 // Write out the type token or filter offset
1131 assert(Entry.HandlerType != ClrHandlerType::Filter && "NYI: filters");
1132 OS.EmitIntValue(Entry.TypeToken, 4);