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(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);
297 /// Information describing an invoke range.
299 MCSymbol *BeginLabel = nullptr;
300 MCSymbol *EndLabel = nullptr;
303 /// If we saw a potentially throwing call between this range and the last
305 bool SawPotentiallyThrowing = false;
308 /// Iterator over the begin/end label pairs of invokes within a basic block.
309 class InvokeLabelIterator {
311 InvokeLabelIterator(WinEHFuncInfo &EHInfo,
312 MachineBasicBlock::const_iterator MBBI,
313 MachineBasicBlock::const_iterator MBBIEnd)
314 : EHInfo(EHInfo), MBBI(MBBI), MBBIEnd(MBBIEnd) {
319 bool operator==(const InvokeLabelIterator &o) const { return MBBI == o.MBBI; }
320 bool operator!=(const InvokeLabelIterator &o) const { return MBBI != o.MBBI; }
321 InvokeRange &operator*() { return CurRange; }
322 InvokeRange *operator->() { return &CurRange; }
323 InvokeLabelIterator &operator++() { return scan(); }
326 // Scan forward to find the next invoke range, or hit the end iterator.
327 InvokeLabelIterator &scan();
329 WinEHFuncInfo &EHInfo;
330 MachineBasicBlock::const_iterator MBBI;
331 MachineBasicBlock::const_iterator MBBIEnd;
332 InvokeRange CurRange;
334 } // end anonymous namespace
336 /// Invoke label range iteration logic. Increment MBBI until we find the next
337 /// EH_LABEL pair, and then update MBBI to point after the end label.
338 InvokeLabelIterator &InvokeLabelIterator::scan() {
340 CurRange = InvokeRange{};
342 for (const MachineInstr &MI : make_range(MBBI, MBBIEnd)) {
343 // Remember if we had to cross a potentially throwing call instruction that
344 // must unwind to caller.
346 CurRange.SawPotentiallyThrowing |=
347 !EHStreamer::callToNoUnwindFunction(&MI);
350 // Find the next EH_LABEL instruction.
354 // If this is a begin label, break out with the state and end label.
355 // Otherwise this is probably a CFI EH_LABEL that we should continue past.
356 MCSymbol *Label = MI.getOperand(0).getMCSymbol();
357 auto StateAndEnd = EHInfo.InvokeToStateMap.find(Label);
358 if (StateAndEnd == EHInfo.InvokeToStateMap.end())
360 MBBI = MachineBasicBlock::const_iterator(&MI);
361 CurRange.BeginLabel = Label;
362 CurRange.EndLabel = StateAndEnd->second.second;
363 CurRange.State = StateAndEnd->second.first;
367 // If we didn't find a begin label, we are done, return the end iterator.
368 if (!CurRange.BeginLabel) {
373 // If this is a begin label, update MBBI to point past the end label.
374 for (; MBBI != MBBIEnd; ++MBBI)
375 if (MBBI->isEHLabel() &&
376 MBBI->getOperand(0).getMCSymbol() == CurRange.EndLabel)
381 /// Utility for making a range for all the invoke ranges.
382 static iterator_range<InvokeLabelIterator>
383 invoke_ranges(WinEHFuncInfo &EHInfo, const MachineBasicBlock &MBB) {
384 return make_range(InvokeLabelIterator(EHInfo, MBB.begin(), MBB.end()),
385 InvokeLabelIterator(EHInfo, MBB.end(), MBB.end()));
388 /// Emit the language-specific data that __C_specific_handler expects. This
389 /// handler lives in the x64 Microsoft C runtime and allows catching or cleaning
390 /// up after faults with __try, __except, and __finally. The typeinfo values
391 /// are not really RTTI data, but pointers to filter functions that return an
392 /// integer (1, 0, or -1) indicating how to handle the exception. For __finally
393 /// blocks and other cleanups, the landing pad label is zero, and the filter
394 /// function is actually a cleanup handler with the same prototype. A catch-all
395 /// entry is modeled with a null filter function field and a non-zero landing
398 /// Possible filter function return values:
399 /// EXCEPTION_EXECUTE_HANDLER (1):
400 /// Jump to the landing pad label after cleanups.
401 /// EXCEPTION_CONTINUE_SEARCH (0):
402 /// Continue searching this table or continue unwinding.
403 /// EXCEPTION_CONTINUE_EXECUTION (-1):
404 /// Resume execution at the trapping PC.
406 /// Inferred table structure:
410 /// imagerel32 LabelStart;
411 /// imagerel32 LabelEnd;
412 /// imagerel32 FilterOrFinally; // One means catch-all.
413 /// imagerel32 LabelLPad; // Zero means __finally.
414 /// } Entries[NumEntries];
416 void WinException::emitCSpecificHandlerTable(const MachineFunction *MF) {
417 auto &OS = *Asm->OutStreamer;
418 MCContext &Ctx = Asm->OutContext;
420 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(MF->getFunction());
422 // Remember what state we were in the last time we found a begin try label.
423 // This allows us to coalesce many nearby invokes with the same state into
425 int LastEHState = -1;
426 MCSymbol *LastBeginLabel = nullptr;
427 MCSymbol *LastEndLabel = nullptr;
429 // Use the assembler to compute the number of table entries through label
430 // difference and division.
431 MCSymbol *TableBegin =
432 Ctx.createTempSymbol("lsda_begin", /*AlwaysAddSuffix=*/true);
434 Ctx.createTempSymbol("lsda_end", /*AlwaysAddSuffix=*/true);
435 const MCExpr *LabelDiff =
436 MCBinaryExpr::createSub(MCSymbolRefExpr::create(TableEnd, Ctx),
437 MCSymbolRefExpr::create(TableBegin, Ctx), Ctx);
438 const MCExpr *EntrySize = MCConstantExpr::create(16, Ctx);
439 const MCExpr *EntryCount = MCBinaryExpr::createDiv(LabelDiff, EntrySize, Ctx);
440 OS.EmitValue(EntryCount, 4);
442 OS.EmitLabel(TableBegin);
444 // Iterate over all the invoke try ranges. Unlike MSVC, LLVM currently only
445 // models exceptions from invokes. LLVM also allows arbitrary reordering of
446 // the code, so our tables end up looking a bit different. Rather than
447 // trying to match MSVC's tables exactly, we emit a denormalized table. For
448 // each range of invokes in the same state, we emit table entries for all
449 // the actions that would be taken in that state. This means our tables are
450 // slightly bigger, which is OK.
451 for (const auto &MBB : *MF) {
452 // Break out before we enter into a finally funclet.
453 // FIXME: We need to emit separate EH tables for cleanups.
454 if (MBB.isEHFuncletEntry() && &MBB != MF->begin())
457 for (InvokeRange &I : invoke_ranges(FuncInfo, MBB)) {
458 // If this invoke is in the same state as the last invoke and there were
459 // no non-throwing calls between it, extend the range to include both
461 if (!I.SawPotentiallyThrowing && I.State == LastEHState) {
462 LastEndLabel = I.EndLabel;
466 // If this invoke ends a previous one, emit all the actions for this
468 if (LastEHState != -1)
469 emitSEHActionsForRange(FuncInfo, LastBeginLabel, LastEndLabel,
472 LastBeginLabel = I.BeginLabel;
473 LastEndLabel = I.EndLabel;
474 LastEHState = I.State;
478 // Hitting the end of the function causes us to emit the range for the
481 emitSEHActionsForRange(FuncInfo, LastBeginLabel, LastEndLabel, LastEHState);
483 OS.EmitLabel(TableEnd);
486 void WinException::emitSEHActionsForRange(WinEHFuncInfo &FuncInfo,
487 MCSymbol *BeginLabel,
488 MCSymbol *EndLabel, int State) {
489 auto &OS = *Asm->OutStreamer;
490 MCContext &Ctx = Asm->OutContext;
492 assert(BeginLabel && EndLabel);
493 while (State != -1) {
494 SEHUnwindMapEntry &UME = FuncInfo.SEHUnwindMap[State];
495 const MCExpr *FilterOrFinally;
496 const MCExpr *ExceptOrNull;
497 auto *Handler = UME.Handler.get<MachineBasicBlock *>();
499 FilterOrFinally = create32bitRef(getMCSymbolForMBB(Asm, Handler));
500 ExceptOrNull = MCConstantExpr::create(0, Ctx);
502 // For an except, the filter can be 1 (catch-all) or a function
504 FilterOrFinally = UME.Filter ? create32bitRef(UME.Filter)
505 : MCConstantExpr::create(1, Ctx);
506 ExceptOrNull = create32bitRef(Handler->getSymbol());
509 OS.EmitValue(getLabelPlusOne(BeginLabel), 4);
510 OS.EmitValue(getLabelPlusOne(EndLabel), 4);
511 OS.EmitValue(FilterOrFinally, 4);
512 OS.EmitValue(ExceptOrNull, 4);
514 assert(UME.ToState < State && "states should decrease");
519 void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
520 const Function *F = MF->getFunction();
521 auto &OS = *Asm->OutStreamer;
522 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
524 StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
526 SmallVector<std::pair<const MCExpr *, int>, 4> IPToStateTable;
527 MCSymbol *FuncInfoXData = nullptr;
528 if (shouldEmitPersonality) {
529 // If we're 64-bit, emit a pointer to the C++ EH data, and build a map from
530 // IPs to state numbers.
532 Asm->OutContext.getOrCreateSymbol(Twine("$cppxdata$", FuncLinkageName));
533 computeIP2StateTable(MF, FuncInfo, IPToStateTable);
535 FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(FuncLinkageName);
536 emitEHRegistrationOffsetLabel(FuncInfo, FuncLinkageName);
539 int UnwindHelpOffset = 0;
540 if (Asm->MAI->usesWindowsCFI())
541 UnwindHelpOffset = getFrameIndexOffset(FuncInfo.UnwindHelpFrameIdx);
543 MCSymbol *UnwindMapXData = nullptr;
544 MCSymbol *TryBlockMapXData = nullptr;
545 MCSymbol *IPToStateXData = nullptr;
546 if (!FuncInfo.CxxUnwindMap.empty())
547 UnwindMapXData = Asm->OutContext.getOrCreateSymbol(
548 Twine("$stateUnwindMap$", FuncLinkageName));
549 if (!FuncInfo.TryBlockMap.empty())
551 Asm->OutContext.getOrCreateSymbol(Twine("$tryMap$", FuncLinkageName));
552 if (!IPToStateTable.empty())
554 Asm->OutContext.getOrCreateSymbol(Twine("$ip2state$", FuncLinkageName));
557 // uint32_t MagicNumber
559 // UnwindMapEntry *UnwindMap;
560 // uint32_t NumTryBlocks;
561 // TryBlockMapEntry *TryBlockMap;
562 // uint32_t IPMapEntries; // always 0 for x86
563 // IPToStateMapEntry *IPToStateMap; // always 0 for x86
564 // uint32_t UnwindHelp; // non-x86 only
565 // ESTypeList *ESTypeList;
568 // EHFlags & 1 -> Synchronous exceptions only, no async exceptions.
569 // EHFlags & 2 -> ???
570 // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue.
571 OS.EmitValueToAlignment(4);
572 OS.EmitLabel(FuncInfoXData);
573 OS.EmitIntValue(0x19930522, 4); // MagicNumber
574 OS.EmitIntValue(FuncInfo.CxxUnwindMap.size(), 4); // MaxState
575 OS.EmitValue(create32bitRef(UnwindMapXData), 4); // UnwindMap
576 OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4); // NumTryBlocks
577 OS.EmitValue(create32bitRef(TryBlockMapXData), 4); // TryBlockMap
578 OS.EmitIntValue(IPToStateTable.size(), 4); // IPMapEntries
579 OS.EmitValue(create32bitRef(IPToStateXData), 4); // IPToStateMap
580 if (Asm->MAI->usesWindowsCFI())
581 OS.EmitIntValue(UnwindHelpOffset, 4); // UnwindHelp
582 OS.EmitIntValue(0, 4); // ESTypeList
583 OS.EmitIntValue(1, 4); // EHFlags
589 if (UnwindMapXData) {
590 OS.EmitLabel(UnwindMapXData);
591 for (const CxxUnwindMapEntry &UME : FuncInfo.CxxUnwindMap) {
592 MCSymbol *CleanupSym =
593 getMCSymbolForMBB(Asm, UME.Cleanup.dyn_cast<MachineBasicBlock *>());
594 OS.EmitIntValue(UME.ToState, 4); // ToState
595 OS.EmitValue(create32bitRef(CleanupSym), 4); // Action
602 // int32_t CatchHigh;
603 // int32_t NumCatches;
604 // HandlerType *HandlerArray;
606 if (TryBlockMapXData) {
607 OS.EmitLabel(TryBlockMapXData);
608 SmallVector<MCSymbol *, 1> HandlerMaps;
609 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
610 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
612 MCSymbol *HandlerMapXData = nullptr;
613 if (!TBME.HandlerArray.empty())
615 Asm->OutContext.getOrCreateSymbol(Twine("$handlerMap$")
618 .concat(FuncLinkageName));
619 HandlerMaps.push_back(HandlerMapXData);
621 // TBMEs should form intervals.
622 assert(0 <= TBME.TryLow && "bad trymap interval");
623 assert(TBME.TryLow <= TBME.TryHigh && "bad trymap interval");
624 assert(TBME.TryHigh < TBME.CatchHigh && "bad trymap interval");
625 assert(TBME.CatchHigh < int(FuncInfo.CxxUnwindMap.size()) &&
626 "bad trymap interval");
628 OS.EmitIntValue(TBME.TryLow, 4); // TryLow
629 OS.EmitIntValue(TBME.TryHigh, 4); // TryHigh
630 OS.EmitIntValue(TBME.CatchHigh, 4); // CatchHigh
631 OS.EmitIntValue(TBME.HandlerArray.size(), 4); // NumCatches
632 OS.EmitValue(create32bitRef(HandlerMapXData), 4); // HandlerArray
635 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
636 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
637 MCSymbol *HandlerMapXData = HandlerMaps[I];
638 if (!HandlerMapXData)
641 // int32_t Adjectives;
642 // TypeDescriptor *Type;
643 // int32_t CatchObjOffset;
644 // void (*Handler)();
645 // int32_t ParentFrameOffset; // x64 only
647 OS.EmitLabel(HandlerMapXData);
648 for (const WinEHHandlerType &HT : TBME.HandlerArray) {
649 // Get the frame escape label with the offset of the catch object. If
650 // the index is INT_MAX, then there is no catch object, and we should
651 // emit an offset of zero, indicating that no copy will occur.
652 const MCExpr *FrameAllocOffsetRef = nullptr;
653 if (HT.CatchObj.FrameIndex != INT_MAX) {
654 int Offset = getFrameIndexOffset(HT.CatchObj.FrameIndex);
655 // For 32-bit, the catch object offset is relative to the end of the
656 // EH registration node. For 64-bit, it's relative to SP at the end of
658 if (!shouldEmitPersonality) {
659 assert(FuncInfo.EHRegNodeEndOffset != INT_MAX);
660 Offset += FuncInfo.EHRegNodeEndOffset;
662 FrameAllocOffsetRef = MCConstantExpr::create(Offset, Asm->OutContext);
664 FrameAllocOffsetRef = MCConstantExpr::create(0, Asm->OutContext);
667 MCSymbol *HandlerSym =
668 getMCSymbolForMBB(Asm, HT.Handler.dyn_cast<MachineBasicBlock *>());
670 OS.EmitIntValue(HT.Adjectives, 4); // Adjectives
671 OS.EmitValue(create32bitRef(HT.TypeDescriptor), 4); // Type
672 OS.EmitValue(FrameAllocOffsetRef, 4); // CatchObjOffset
673 OS.EmitValue(create32bitRef(HandlerSym), 4); // Handler
675 if (shouldEmitPersonality) {
676 // Keep this in sync with X86FrameLowering::emitPrologue.
677 int ParentFrameOffset =
678 16 + 8 + MF->getFrameInfo()->getMaxCallFrameSize();
679 OS.EmitIntValue(ParentFrameOffset, 4); // ParentFrameOffset
685 // IPToStateMapEntry {
689 if (IPToStateXData) {
690 OS.EmitLabel(IPToStateXData);
691 for (auto &IPStatePair : IPToStateTable) {
692 OS.EmitValue(IPStatePair.first, 4); // IP
693 OS.EmitIntValue(IPStatePair.second, 4); // State
698 void WinException::computeIP2StateTable(
699 const MachineFunction *MF, WinEHFuncInfo &FuncInfo,
700 SmallVectorImpl<std::pair<const MCExpr *, int>> &IPToStateTable) {
701 // Remember what state we were in the last time we found a begin try label.
702 // This allows us to coalesce many nearby invokes with the same state into one
704 int LastEHState = -1;
705 MCSymbol *LastEndLabel = Asm->getFunctionBegin();
706 assert(LastEndLabel && "need local function start label");
708 // Indicate that all calls from the prologue to the first invoke unwind to
709 // caller. We handle this as a special case since other ranges starting at end
710 // labels need to use LtmpN+1.
711 IPToStateTable.push_back(std::make_pair(create32bitRef(LastEndLabel), -1));
713 for (const auto &MBB : *MF) {
714 // FIXME: Do we need to emit entries for funclet base states?
716 for (InvokeRange &I : invoke_ranges(FuncInfo, MBB)) {
717 assert(I.BeginLabel && I.EndLabel);
718 // If there was a potentially throwing call between this begin label and
719 // the last end label, we need an extra base state entry to indicate that
720 // those calls unwind directly to the caller.
721 if (I.SawPotentiallyThrowing && LastEHState != -1) {
722 IPToStateTable.push_back(
723 std::make_pair(getLabelPlusOne(LastEndLabel), -1));
727 // Emit an entry indicating that PCs after 'Label' have this EH state.
728 if (I.State != LastEHState)
729 IPToStateTable.push_back(
730 std::make_pair(getLabelPlusOne(I.BeginLabel), I.State));
731 LastEHState = I.State;
732 LastEndLabel = I.EndLabel;
736 if (LastEndLabel != Asm->getFunctionBegin()) {
737 // Indicate that all calls from the last invoke until the epilogue unwind to
738 // caller. This also ensures that we have at least one ip2state entry, if
739 // somehow all invokes were deleted during CodeGen.
740 IPToStateTable.push_back(std::make_pair(getLabelPlusOne(LastEndLabel), -1));
744 void WinException::emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo,
745 StringRef FLinkageName) {
746 // Outlined helpers called by the EH runtime need to know the offset of the EH
747 // registration in order to recover the parent frame pointer. Now that we know
748 // we've code generated the parent, we can emit the label assignment that
749 // those helpers use to get the offset of the registration node.
750 assert(FuncInfo.EHRegNodeEscapeIndex != INT_MAX &&
751 "no EH reg node localescape index");
752 MCSymbol *ParentFrameOffset =
753 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(FLinkageName);
754 MCSymbol *RegistrationOffsetSym = Asm->OutContext.getOrCreateFrameAllocSymbol(
755 FLinkageName, FuncInfo.EHRegNodeEscapeIndex);
756 const MCExpr *RegistrationOffsetSymRef =
757 MCSymbolRefExpr::create(RegistrationOffsetSym, Asm->OutContext);
758 Asm->OutStreamer->EmitAssignment(ParentFrameOffset, RegistrationOffsetSymRef);
761 /// Emit the language-specific data that _except_handler3 and 4 expect. This is
762 /// functionally equivalent to the __C_specific_handler table, except it is
763 /// indexed by state number instead of IP.
764 void WinException::emitExceptHandlerTable(const MachineFunction *MF) {
765 MCStreamer &OS = *Asm->OutStreamer;
766 const Function *F = MF->getFunction();
767 StringRef FLinkageName = GlobalValue::getRealLinkageName(F->getName());
769 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
770 emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
772 // Emit the __ehtable label that we use for llvm.x86.seh.lsda.
773 MCSymbol *LSDALabel = Asm->OutContext.getOrCreateLSDASymbol(FLinkageName);
774 OS.EmitValueToAlignment(4);
775 OS.EmitLabel(LSDALabel);
777 const Function *Per =
778 dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
779 StringRef PerName = Per->getName();
781 if (PerName == "_except_handler4") {
782 // The LSDA for _except_handler4 starts with this struct, followed by the
785 // struct EH4ScopeTable {
786 // int32_t GSCookieOffset;
787 // int32_t GSCookieXOROffset;
788 // int32_t EHCookieOffset;
789 // int32_t EHCookieXOROffset;
790 // ScopeTableEntry ScopeRecord[];
793 // Only the EHCookieOffset field appears to vary, and it appears to be the
794 // offset from the final saved SP value to the retaddr.
795 OS.EmitIntValue(-2, 4);
796 OS.EmitIntValue(0, 4);
798 OS.EmitIntValue(9999, 4);
799 OS.EmitIntValue(0, 4);
803 assert(!FuncInfo.SEHUnwindMap.empty());
804 for (SEHUnwindMapEntry &UME : FuncInfo.SEHUnwindMap) {
805 MCSymbol *ExceptOrFinally =
806 UME.Handler.get<MachineBasicBlock *>()->getSymbol();
807 // -1 is usually the base state for "unwind to caller", but for
808 // _except_handler4 it's -2. Do that replacement here if necessary.
809 int ToState = UME.ToState == -1 ? BaseState : UME.ToState;
810 OS.EmitIntValue(ToState, 4); // ToState
811 OS.EmitValue(create32bitRef(UME.Filter), 4); // Filter
812 OS.EmitValue(create32bitRef(ExceptOrFinally), 4); // Except/Finally