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);
143 emitExceptionTable();
145 Asm->OutStreamer->PopSection();
149 /// Retreive the MCSymbol for a GlobalValue or MachineBasicBlock.
150 static MCSymbol *getMCSymbolForMBB(AsmPrinter *Asm,
151 const MachineBasicBlock *MBB) {
155 assert(MBB->isEHFuncletEntry());
157 // Give catches and cleanups a name based off of their parent function and
158 // their funclet entry block's number.
159 const MachineFunction *MF = MBB->getParent();
160 const Function *F = MF->getFunction();
161 StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
162 MCContext &Ctx = MF->getContext();
163 StringRef HandlerPrefix = MBB->isCleanupFuncletEntry() ? "dtor" : "catch";
164 return Ctx.getOrCreateSymbol("?" + HandlerPrefix + "$" +
165 Twine(MBB->getNumber()) + "@?0?" +
166 FuncLinkageName + "@4HA");
169 void WinException::beginFunclet(const MachineBasicBlock &MBB,
171 CurrentFuncletEntry = &MBB;
173 const Function *F = Asm->MF->getFunction();
174 // If a symbol was not provided for the funclet, invent one.
176 Sym = getMCSymbolForMBB(Asm, &MBB);
178 // Describe our funclet symbol as a function with internal linkage.
179 Asm->OutStreamer->BeginCOFFSymbolDef(Sym);
180 Asm->OutStreamer->EmitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC);
181 Asm->OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
182 << COFF::SCT_COMPLEX_TYPE_SHIFT);
183 Asm->OutStreamer->EndCOFFSymbolDef();
185 // We want our funclet's entry point to be aligned such that no nops will be
186 // present after the label.
187 Asm->EmitAlignment(std::max(Asm->MF->getAlignment(), MBB.getAlignment()),
190 // Now that we've emitted the alignment directive, point at our funclet.
191 Asm->OutStreamer->EmitLabel(Sym);
194 // Mark 'Sym' as starting our funclet.
195 if (shouldEmitMoves || shouldEmitPersonality)
196 Asm->OutStreamer->EmitWinCFIStartProc(Sym);
198 if (shouldEmitPersonality) {
199 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
200 const Function *PerFn = nullptr;
202 // Determine which personality routine we are using for this funclet.
203 if (F->hasPersonalityFn())
204 PerFn = dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
205 const MCSymbol *PersHandlerSym =
206 TLOF.getCFIPersonalitySymbol(PerFn, *Asm->Mang, Asm->TM, MMI);
208 // Classify the personality routine so that we may reason about it.
209 EHPersonality Per = EHPersonality::Unknown;
210 if (F->hasPersonalityFn())
211 Per = classifyEHPersonality(F->getPersonalityFn());
213 // Do not emit a .seh_handler directive if it is a C++ cleanup funclet.
214 if (Per != EHPersonality::MSVC_CXX ||
215 !CurrentFuncletEntry->isCleanupFuncletEntry())
216 Asm->OutStreamer->EmitWinEHHandler(PersHandlerSym, true, true);
220 void WinException::endFunclet() {
221 // No funclet to process? Great, we have nothing to do.
222 if (!CurrentFuncletEntry)
225 if (shouldEmitMoves || shouldEmitPersonality) {
226 const Function *F = Asm->MF->getFunction();
227 EHPersonality Per = EHPersonality::Unknown;
228 if (F->hasPersonalityFn())
229 Per = classifyEHPersonality(F->getPersonalityFn());
231 // The .seh_handlerdata directive implicitly switches section, push the
232 // current section so that we may return to it.
233 Asm->OutStreamer->PushSection();
235 // Emit an UNWIND_INFO struct describing the prologue.
236 Asm->OutStreamer->EmitWinEHHandlerData();
238 if (Per == EHPersonality::MSVC_CXX && shouldEmitPersonality &&
239 !CurrentFuncletEntry->isCleanupFuncletEntry()) {
240 // If this is a C++ catch funclet (or the parent function),
241 // emit a reference to the LSDA for the parent function.
242 StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
243 MCSymbol *FuncInfoXData = Asm->OutContext.getOrCreateSymbol(
244 Twine("$cppxdata$", FuncLinkageName));
245 Asm->OutStreamer->EmitValue(create32bitRef(FuncInfoXData), 4);
246 } else if (Per == EHPersonality::MSVC_Win64SEH && MMI->hasEHFunclets() &&
247 !CurrentFuncletEntry->isEHFuncletEntry()) {
248 // If this is the parent function in Win64 SEH, emit the LSDA immediately
249 // following .seh_handlerdata.
250 emitCSpecificHandlerTable(Asm->MF);
253 // Switch back to the previous section now that we are done writing to
255 Asm->OutStreamer->PopSection();
257 // Emit a .seh_endproc directive to mark the end of the function.
258 Asm->OutStreamer->EmitWinCFIEndProc();
261 // Let's make sure we don't try to end the same funclet twice.
262 CurrentFuncletEntry = nullptr;
265 const MCExpr *WinException::create32bitRef(const MCSymbol *Value) {
267 return MCConstantExpr::create(0, Asm->OutContext);
268 return MCSymbolRefExpr::create(Value, useImageRel32
269 ? MCSymbolRefExpr::VK_COFF_IMGREL32
270 : MCSymbolRefExpr::VK_None,
274 const MCExpr *WinException::create32bitRef(const Value *V) {
276 return MCConstantExpr::create(0, Asm->OutContext);
277 if (const auto *GV = dyn_cast<GlobalValue>(V))
278 return create32bitRef(Asm->getSymbol(GV));
279 return create32bitRef(MMI->getAddrLabelSymbol(cast<BasicBlock>(V)));
282 const MCExpr *WinException::getLabelPlusOne(const MCSymbol *Label) {
283 return MCBinaryExpr::createAdd(create32bitRef(Label),
284 MCConstantExpr::create(1, Asm->OutContext),
288 int WinException::getFrameIndexOffset(int FrameIndex) {
289 const TargetFrameLowering &TFI = *Asm->MF->getSubtarget().getFrameLowering();
291 if (Asm->MAI->usesWindowsCFI())
292 return TFI.getFrameIndexReferenceFromSP(*Asm->MF, FrameIndex, UnusedReg);
293 return TFI.getFrameIndexReference(*Asm->MF, FrameIndex, UnusedReg);
298 /// Top-level state used to represent unwind to caller
299 const int NullState = -1;
301 struct InvokeStateChange {
302 /// EH Label immediately after the last invoke in the previous state, or
303 /// nullptr if the previous state was the null state.
304 const MCSymbol *PreviousEndLabel;
306 /// EH label immediately before the first invoke in the new state, or nullptr
307 /// if the new state is the null state.
308 const MCSymbol *NewStartLabel;
310 /// State of the invoke following NewStartLabel, or NullState to indicate
311 /// the presence of calls which may unwind to caller.
315 /// Iterator that reports all the invoke state changes in a range of machine
316 /// basic blocks. Changes to the null state are reported whenever a call that
317 /// may unwind to caller is encountered. The MBB range is expected to be an
318 /// entire function or funclet, and the start and end of the range are treated
319 /// as being in the NullState even if there's not an unwind-to-caller call
320 /// before the first invoke or after the last one (i.e., the first state change
321 /// reported is the first change to something other than NullState, and a
322 /// change back to NullState is always reported at the end of iteration).
323 class InvokeStateChangeIterator {
324 InvokeStateChangeIterator(WinEHFuncInfo &EHInfo,
325 MachineFunction::const_iterator MFI,
326 MachineFunction::const_iterator MFE,
327 MachineBasicBlock::const_iterator MBBI)
328 : EHInfo(EHInfo), MFI(MFI), MFE(MFE), MBBI(MBBI) {
329 LastStateChange.PreviousEndLabel = nullptr;
330 LastStateChange.NewStartLabel = nullptr;
331 LastStateChange.NewState = NullState;
336 static iterator_range<InvokeStateChangeIterator>
337 range(WinEHFuncInfo &EHInfo, const MachineFunction &MF) {
338 // Reject empty MFs to simplify bookkeeping by ensuring that we can get the
339 // end of the last block.
341 auto FuncBegin = MF.begin();
342 auto FuncEnd = MF.end();
343 auto BlockBegin = FuncBegin->begin();
344 auto BlockEnd = MF.back().end();
346 InvokeStateChangeIterator(EHInfo, FuncBegin, FuncEnd, BlockBegin),
347 InvokeStateChangeIterator(EHInfo, FuncEnd, FuncEnd, BlockEnd));
349 static iterator_range<InvokeStateChangeIterator>
350 range(WinEHFuncInfo &EHInfo, MachineFunction::const_iterator Begin,
351 MachineFunction::const_iterator End) {
352 // Reject empty ranges to simplify bookkeeping by ensuring that we can get
353 // the end of the last block.
354 assert(Begin != End);
355 auto BlockBegin = Begin->begin();
356 auto BlockEnd = std::prev(End)->end();
357 return make_range(InvokeStateChangeIterator(EHInfo, Begin, End, BlockBegin),
358 InvokeStateChangeIterator(EHInfo, End, End, BlockEnd));
362 bool operator==(const InvokeStateChangeIterator &O) const {
363 // Must be visiting same block.
366 // Must be visiting same isntr.
369 // At end of block/instr iteration, we can still have two distinct states:
370 // one to report the final EndLabel, and another indicating the end of the
371 // state change iteration. Check for CurrentEndLabel equality to
372 // distinguish these.
373 return CurrentEndLabel == O.CurrentEndLabel;
376 bool operator!=(const InvokeStateChangeIterator &O) const {
377 return !operator==(O);
379 InvokeStateChange &operator*() { return LastStateChange; }
380 InvokeStateChange *operator->() { return &LastStateChange; }
381 InvokeStateChangeIterator &operator++() { return scan(); }
384 InvokeStateChangeIterator &scan();
386 WinEHFuncInfo &EHInfo;
387 const MCSymbol *CurrentEndLabel = nullptr;
388 MachineFunction::const_iterator MFI;
389 MachineFunction::const_iterator MFE;
390 MachineBasicBlock::const_iterator MBBI;
391 InvokeStateChange LastStateChange;
392 bool VisitingInvoke = false;
395 } // end anonymous namespace
397 InvokeStateChangeIterator &InvokeStateChangeIterator::scan() {
398 bool IsNewBlock = false;
399 for (; MFI != MFE; ++MFI, IsNewBlock = true) {
402 for (auto MBBE = MFI->end(); MBBI != MBBE; ++MBBI) {
403 const MachineInstr &MI = *MBBI;
404 if (!VisitingInvoke && LastStateChange.NewState != NullState &&
405 MI.isCall() && !EHStreamer::callToNoUnwindFunction(&MI)) {
406 // Indicate a change of state to the null state. We don't have
407 // start/end EH labels handy but the caller won't expect them for
408 // null state regions.
409 LastStateChange.PreviousEndLabel = CurrentEndLabel;
410 LastStateChange.NewStartLabel = nullptr;
411 LastStateChange.NewState = NullState;
412 CurrentEndLabel = nullptr;
413 // Don't re-visit this instr on the next scan
418 // All other state changes are at EH labels before/after invokes.
421 MCSymbol *Label = MI.getOperand(0).getMCSymbol();
422 if (Label == CurrentEndLabel) {
423 VisitingInvoke = false;
426 auto InvokeMapIter = EHInfo.InvokeToStateMap.find(Label);
427 // Ignore EH labels that aren't the ones inserted before an invoke
428 if (InvokeMapIter == EHInfo.InvokeToStateMap.end())
430 auto &StateAndEnd = InvokeMapIter->second;
431 int NewState = StateAndEnd.first;
432 // Ignore EH labels explicitly annotated with the null state (which
433 // can happen for invokes that unwind to a chain of endpads the last
434 // of which unwinds to caller). We'll see the subsequent invoke and
435 // report a transition to the null state same as we do for calls.
436 if (NewState == NullState)
438 // Keep track of the fact that we're between EH start/end labels so
439 // we know not to treat the inoke we'll see as unwinding to caller.
440 VisitingInvoke = true;
441 if (NewState == LastStateChange.NewState) {
442 // The state isn't actually changing here. Record the new end and
444 CurrentEndLabel = StateAndEnd.second;
447 // Found a state change to report
448 LastStateChange.PreviousEndLabel = CurrentEndLabel;
449 LastStateChange.NewStartLabel = Label;
450 LastStateChange.NewState = NewState;
451 // Start keeping track of the new current end
452 CurrentEndLabel = StateAndEnd.second;
453 // Don't re-visit this instr on the next scan
458 // Iteration hit the end of the block range.
459 if (LastStateChange.NewState != NullState) {
460 // Report the end of the last new state
461 LastStateChange.PreviousEndLabel = CurrentEndLabel;
462 LastStateChange.NewStartLabel = nullptr;
463 LastStateChange.NewState = NullState;
464 // Leave CurrentEndLabel non-null to distinguish this state from end.
465 assert(CurrentEndLabel != nullptr);
468 // We've reported all state changes and hit the end state.
469 CurrentEndLabel = nullptr;
473 /// Emit the language-specific data that __C_specific_handler expects. This
474 /// handler lives in the x64 Microsoft C runtime and allows catching or cleaning
475 /// up after faults with __try, __except, and __finally. The typeinfo values
476 /// are not really RTTI data, but pointers to filter functions that return an
477 /// integer (1, 0, or -1) indicating how to handle the exception. For __finally
478 /// blocks and other cleanups, the landing pad label is zero, and the filter
479 /// function is actually a cleanup handler with the same prototype. A catch-all
480 /// entry is modeled with a null filter function field and a non-zero landing
483 /// Possible filter function return values:
484 /// EXCEPTION_EXECUTE_HANDLER (1):
485 /// Jump to the landing pad label after cleanups.
486 /// EXCEPTION_CONTINUE_SEARCH (0):
487 /// Continue searching this table or continue unwinding.
488 /// EXCEPTION_CONTINUE_EXECUTION (-1):
489 /// Resume execution at the trapping PC.
491 /// Inferred table structure:
495 /// imagerel32 LabelStart;
496 /// imagerel32 LabelEnd;
497 /// imagerel32 FilterOrFinally; // One means catch-all.
498 /// imagerel32 LabelLPad; // Zero means __finally.
499 /// } Entries[NumEntries];
501 void WinException::emitCSpecificHandlerTable(const MachineFunction *MF) {
502 auto &OS = *Asm->OutStreamer;
503 MCContext &Ctx = Asm->OutContext;
505 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(MF->getFunction());
506 // Use the assembler to compute the number of table entries through label
507 // difference and division.
508 MCSymbol *TableBegin =
509 Ctx.createTempSymbol("lsda_begin", /*AlwaysAddSuffix=*/true);
511 Ctx.createTempSymbol("lsda_end", /*AlwaysAddSuffix=*/true);
512 const MCExpr *LabelDiff =
513 MCBinaryExpr::createSub(MCSymbolRefExpr::create(TableEnd, Ctx),
514 MCSymbolRefExpr::create(TableBegin, Ctx), Ctx);
515 const MCExpr *EntrySize = MCConstantExpr::create(16, Ctx);
516 const MCExpr *EntryCount = MCBinaryExpr::createDiv(LabelDiff, EntrySize, Ctx);
517 OS.EmitValue(EntryCount, 4);
519 OS.EmitLabel(TableBegin);
521 // Iterate over all the invoke try ranges. Unlike MSVC, LLVM currently only
522 // models exceptions from invokes. LLVM also allows arbitrary reordering of
523 // the code, so our tables end up looking a bit different. Rather than
524 // trying to match MSVC's tables exactly, we emit a denormalized table. For
525 // each range of invokes in the same state, we emit table entries for all
526 // the actions that would be taken in that state. This means our tables are
527 // slightly bigger, which is OK.
528 const MCSymbol *LastStartLabel = nullptr;
529 int LastEHState = -1;
530 // Break out before we enter into a finally funclet.
531 // FIXME: We need to emit separate EH tables for cleanups.
532 MachineFunction::const_iterator End = MF->end();
533 MachineFunction::const_iterator Stop = std::next(MF->begin());
534 while (Stop != End && !Stop->isEHFuncletEntry())
536 for (const auto &StateChange :
537 InvokeStateChangeIterator::range(FuncInfo, MF->begin(), Stop)) {
538 // Emit all the actions for the state we just transitioned out of
539 // if it was not the null state
540 if (LastEHState != -1)
541 emitSEHActionsForRange(FuncInfo, LastStartLabel,
542 StateChange.PreviousEndLabel, LastEHState);
543 LastStartLabel = StateChange.NewStartLabel;
544 LastEHState = StateChange.NewState;
547 OS.EmitLabel(TableEnd);
550 void WinException::emitSEHActionsForRange(WinEHFuncInfo &FuncInfo,
551 const MCSymbol *BeginLabel,
552 const MCSymbol *EndLabel, int State) {
553 auto &OS = *Asm->OutStreamer;
554 MCContext &Ctx = Asm->OutContext;
556 assert(BeginLabel && EndLabel);
557 while (State != -1) {
558 SEHUnwindMapEntry &UME = FuncInfo.SEHUnwindMap[State];
559 const MCExpr *FilterOrFinally;
560 const MCExpr *ExceptOrNull;
561 auto *Handler = UME.Handler.get<MachineBasicBlock *>();
563 FilterOrFinally = create32bitRef(getMCSymbolForMBB(Asm, Handler));
564 ExceptOrNull = MCConstantExpr::create(0, Ctx);
566 // For an except, the filter can be 1 (catch-all) or a function
568 FilterOrFinally = UME.Filter ? create32bitRef(UME.Filter)
569 : MCConstantExpr::create(1, Ctx);
570 ExceptOrNull = create32bitRef(Handler->getSymbol());
573 OS.EmitValue(getLabelPlusOne(BeginLabel), 4);
574 OS.EmitValue(getLabelPlusOne(EndLabel), 4);
575 OS.EmitValue(FilterOrFinally, 4);
576 OS.EmitValue(ExceptOrNull, 4);
578 assert(UME.ToState < State && "states should decrease");
583 void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
584 const Function *F = MF->getFunction();
585 auto &OS = *Asm->OutStreamer;
586 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
588 StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
590 SmallVector<std::pair<const MCExpr *, int>, 4> IPToStateTable;
591 MCSymbol *FuncInfoXData = nullptr;
592 if (shouldEmitPersonality) {
593 // If we're 64-bit, emit a pointer to the C++ EH data, and build a map from
594 // IPs to state numbers.
596 Asm->OutContext.getOrCreateSymbol(Twine("$cppxdata$", FuncLinkageName));
597 computeIP2StateTable(MF, FuncInfo, IPToStateTable);
599 FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(FuncLinkageName);
600 emitEHRegistrationOffsetLabel(FuncInfo, FuncLinkageName);
603 int UnwindHelpOffset = 0;
604 if (Asm->MAI->usesWindowsCFI())
605 UnwindHelpOffset = getFrameIndexOffset(FuncInfo.UnwindHelpFrameIdx);
607 MCSymbol *UnwindMapXData = nullptr;
608 MCSymbol *TryBlockMapXData = nullptr;
609 MCSymbol *IPToStateXData = nullptr;
610 if (!FuncInfo.CxxUnwindMap.empty())
611 UnwindMapXData = Asm->OutContext.getOrCreateSymbol(
612 Twine("$stateUnwindMap$", FuncLinkageName));
613 if (!FuncInfo.TryBlockMap.empty())
615 Asm->OutContext.getOrCreateSymbol(Twine("$tryMap$", FuncLinkageName));
616 if (!IPToStateTable.empty())
618 Asm->OutContext.getOrCreateSymbol(Twine("$ip2state$", FuncLinkageName));
621 // uint32_t MagicNumber
623 // UnwindMapEntry *UnwindMap;
624 // uint32_t NumTryBlocks;
625 // TryBlockMapEntry *TryBlockMap;
626 // uint32_t IPMapEntries; // always 0 for x86
627 // IPToStateMapEntry *IPToStateMap; // always 0 for x86
628 // uint32_t UnwindHelp; // non-x86 only
629 // ESTypeList *ESTypeList;
632 // EHFlags & 1 -> Synchronous exceptions only, no async exceptions.
633 // EHFlags & 2 -> ???
634 // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue.
635 OS.EmitValueToAlignment(4);
636 OS.EmitLabel(FuncInfoXData);
637 OS.EmitIntValue(0x19930522, 4); // MagicNumber
638 OS.EmitIntValue(FuncInfo.CxxUnwindMap.size(), 4); // MaxState
639 OS.EmitValue(create32bitRef(UnwindMapXData), 4); // UnwindMap
640 OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4); // NumTryBlocks
641 OS.EmitValue(create32bitRef(TryBlockMapXData), 4); // TryBlockMap
642 OS.EmitIntValue(IPToStateTable.size(), 4); // IPMapEntries
643 OS.EmitValue(create32bitRef(IPToStateXData), 4); // IPToStateMap
644 if (Asm->MAI->usesWindowsCFI())
645 OS.EmitIntValue(UnwindHelpOffset, 4); // UnwindHelp
646 OS.EmitIntValue(0, 4); // ESTypeList
647 OS.EmitIntValue(1, 4); // EHFlags
653 if (UnwindMapXData) {
654 OS.EmitLabel(UnwindMapXData);
655 for (const CxxUnwindMapEntry &UME : FuncInfo.CxxUnwindMap) {
656 MCSymbol *CleanupSym =
657 getMCSymbolForMBB(Asm, UME.Cleanup.dyn_cast<MachineBasicBlock *>());
658 OS.EmitIntValue(UME.ToState, 4); // ToState
659 OS.EmitValue(create32bitRef(CleanupSym), 4); // Action
666 // int32_t CatchHigh;
667 // int32_t NumCatches;
668 // HandlerType *HandlerArray;
670 if (TryBlockMapXData) {
671 OS.EmitLabel(TryBlockMapXData);
672 SmallVector<MCSymbol *, 1> HandlerMaps;
673 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
674 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
676 MCSymbol *HandlerMapXData = nullptr;
677 if (!TBME.HandlerArray.empty())
679 Asm->OutContext.getOrCreateSymbol(Twine("$handlerMap$")
682 .concat(FuncLinkageName));
683 HandlerMaps.push_back(HandlerMapXData);
685 // TBMEs should form intervals.
686 assert(0 <= TBME.TryLow && "bad trymap interval");
687 assert(TBME.TryLow <= TBME.TryHigh && "bad trymap interval");
688 assert(TBME.TryHigh < TBME.CatchHigh && "bad trymap interval");
689 assert(TBME.CatchHigh < int(FuncInfo.CxxUnwindMap.size()) &&
690 "bad trymap interval");
692 OS.EmitIntValue(TBME.TryLow, 4); // TryLow
693 OS.EmitIntValue(TBME.TryHigh, 4); // TryHigh
694 OS.EmitIntValue(TBME.CatchHigh, 4); // CatchHigh
695 OS.EmitIntValue(TBME.HandlerArray.size(), 4); // NumCatches
696 OS.EmitValue(create32bitRef(HandlerMapXData), 4); // HandlerArray
699 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
700 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
701 MCSymbol *HandlerMapXData = HandlerMaps[I];
702 if (!HandlerMapXData)
705 // int32_t Adjectives;
706 // TypeDescriptor *Type;
707 // int32_t CatchObjOffset;
708 // void (*Handler)();
709 // int32_t ParentFrameOffset; // x64 only
711 OS.EmitLabel(HandlerMapXData);
712 for (const WinEHHandlerType &HT : TBME.HandlerArray) {
713 // Get the frame escape label with the offset of the catch object. If
714 // the index is INT_MAX, then there is no catch object, and we should
715 // emit an offset of zero, indicating that no copy will occur.
716 const MCExpr *FrameAllocOffsetRef = nullptr;
717 if (HT.CatchObj.FrameIndex != INT_MAX) {
718 int Offset = getFrameIndexOffset(HT.CatchObj.FrameIndex);
719 // For 32-bit, the catch object offset is relative to the end of the
720 // EH registration node. For 64-bit, it's relative to SP at the end of
722 if (!shouldEmitPersonality) {
723 assert(FuncInfo.EHRegNodeEndOffset != INT_MAX);
724 Offset += FuncInfo.EHRegNodeEndOffset;
726 FrameAllocOffsetRef = MCConstantExpr::create(Offset, Asm->OutContext);
728 FrameAllocOffsetRef = MCConstantExpr::create(0, Asm->OutContext);
731 MCSymbol *HandlerSym =
732 getMCSymbolForMBB(Asm, HT.Handler.dyn_cast<MachineBasicBlock *>());
734 OS.EmitIntValue(HT.Adjectives, 4); // Adjectives
735 OS.EmitValue(create32bitRef(HT.TypeDescriptor), 4); // Type
736 OS.EmitValue(FrameAllocOffsetRef, 4); // CatchObjOffset
737 OS.EmitValue(create32bitRef(HandlerSym), 4); // Handler
739 if (shouldEmitPersonality) {
740 // Keep this in sync with X86FrameLowering::emitPrologue.
741 int ParentFrameOffset =
742 16 + 8 + MF->getFrameInfo()->getMaxCallFrameSize();
743 OS.EmitIntValue(ParentFrameOffset, 4); // ParentFrameOffset
749 // IPToStateMapEntry {
753 if (IPToStateXData) {
754 OS.EmitLabel(IPToStateXData);
755 for (auto &IPStatePair : IPToStateTable) {
756 OS.EmitValue(IPStatePair.first, 4); // IP
757 OS.EmitIntValue(IPStatePair.second, 4); // State
762 void WinException::computeIP2StateTable(
763 const MachineFunction *MF, WinEHFuncInfo &FuncInfo,
764 SmallVectorImpl<std::pair<const MCExpr *, int>> &IPToStateTable) {
765 // Indicate that all calls from the prologue to the first invoke unwind to
766 // caller. We handle this as a special case since other ranges starting at end
767 // labels need to use LtmpN+1.
768 MCSymbol *StartLabel = Asm->getFunctionBegin();
769 assert(StartLabel && "need local function start label");
770 IPToStateTable.push_back(std::make_pair(create32bitRef(StartLabel), -1));
772 // FIXME: Do we need to emit entries for funclet base states?
773 for (const auto &StateChange :
774 InvokeStateChangeIterator::range(FuncInfo, *MF)) {
775 // Compute the label to report as the start of this entry; use the EH start
776 // label for the invoke if we have one, otherwise (this is a call which may
777 // unwind to our caller and does not have an EH start label, so) use the
778 // previous end label.
779 const MCSymbol *ChangeLabel = StateChange.NewStartLabel;
781 ChangeLabel = StateChange.PreviousEndLabel;
782 // Emit an entry indicating that PCs after 'Label' have this EH state.
783 IPToStateTable.push_back(
784 std::make_pair(getLabelPlusOne(ChangeLabel), StateChange.NewState));
788 void WinException::emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo,
789 StringRef FLinkageName) {
790 // Outlined helpers called by the EH runtime need to know the offset of the EH
791 // registration in order to recover the parent frame pointer. Now that we know
792 // we've code generated the parent, we can emit the label assignment that
793 // those helpers use to get the offset of the registration node.
794 assert(FuncInfo.EHRegNodeEscapeIndex != INT_MAX &&
795 "no EH reg node localescape index");
796 MCSymbol *ParentFrameOffset =
797 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(FLinkageName);
798 MCSymbol *RegistrationOffsetSym = Asm->OutContext.getOrCreateFrameAllocSymbol(
799 FLinkageName, FuncInfo.EHRegNodeEscapeIndex);
800 const MCExpr *RegistrationOffsetSymRef =
801 MCSymbolRefExpr::create(RegistrationOffsetSym, Asm->OutContext);
802 Asm->OutStreamer->EmitAssignment(ParentFrameOffset, RegistrationOffsetSymRef);
805 /// Emit the language-specific data that _except_handler3 and 4 expect. This is
806 /// functionally equivalent to the __C_specific_handler table, except it is
807 /// indexed by state number instead of IP.
808 void WinException::emitExceptHandlerTable(const MachineFunction *MF) {
809 MCStreamer &OS = *Asm->OutStreamer;
810 const Function *F = MF->getFunction();
811 StringRef FLinkageName = GlobalValue::getRealLinkageName(F->getName());
813 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
814 emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
816 // Emit the __ehtable label that we use for llvm.x86.seh.lsda.
817 MCSymbol *LSDALabel = Asm->OutContext.getOrCreateLSDASymbol(FLinkageName);
818 OS.EmitValueToAlignment(4);
819 OS.EmitLabel(LSDALabel);
821 const Function *Per =
822 dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
823 StringRef PerName = Per->getName();
825 if (PerName == "_except_handler4") {
826 // The LSDA for _except_handler4 starts with this struct, followed by the
829 // struct EH4ScopeTable {
830 // int32_t GSCookieOffset;
831 // int32_t GSCookieXOROffset;
832 // int32_t EHCookieOffset;
833 // int32_t EHCookieXOROffset;
834 // ScopeTableEntry ScopeRecord[];
837 // Only the EHCookieOffset field appears to vary, and it appears to be the
838 // offset from the final saved SP value to the retaddr.
839 OS.EmitIntValue(-2, 4);
840 OS.EmitIntValue(0, 4);
842 OS.EmitIntValue(9999, 4);
843 OS.EmitIntValue(0, 4);
847 assert(!FuncInfo.SEHUnwindMap.empty());
848 for (SEHUnwindMapEntry &UME : FuncInfo.SEHUnwindMap) {
849 MCSymbol *ExceptOrFinally =
850 UME.Handler.get<MachineBasicBlock *>()->getSymbol();
851 // -1 is usually the base state for "unwind to caller", but for
852 // _except_handler4 it's -2. Do that replacement here if necessary.
853 int ToState = UME.ToState == -1 ? BaseState : UME.ToState;
854 OS.EmitIntValue(ToState, 4); // ToState
855 OS.EmitValue(create32bitRef(UME.Filter), 4); // Filter
856 OS.EmitValue(create32bitRef(ExceptOrFinally), 4); // Except/Finally