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 GlobalValue *GV) {
278 return MCConstantExpr::create(0, Asm->OutContext);
279 return create32bitRef(Asm->getSymbol(GV));
282 const MCExpr *WinException::getLabelPlusOne(const MCSymbol *Label) {
283 return MCBinaryExpr::createAdd(create32bitRef(Label),
284 MCConstantExpr::create(1, Asm->OutContext),
288 const MCExpr *WinException::getOffset(const MCSymbol *OffsetOf,
289 const MCSymbol *OffsetFrom) {
290 return MCBinaryExpr::createSub(
291 MCSymbolRefExpr::create(OffsetOf, Asm->OutContext),
292 MCSymbolRefExpr::create(OffsetFrom, Asm->OutContext), Asm->OutContext);
295 const MCExpr *WinException::getOffsetPlusOne(const MCSymbol *OffsetOf,
296 const MCSymbol *OffsetFrom) {
297 return MCBinaryExpr::createAdd(getOffset(OffsetOf, OffsetFrom),
298 MCConstantExpr::create(1, Asm->OutContext),
302 int WinException::getFrameIndexOffset(int FrameIndex,
303 const WinEHFuncInfo &FuncInfo) {
304 const TargetFrameLowering &TFI = *Asm->MF->getSubtarget().getFrameLowering();
306 if (Asm->MAI->usesWindowsCFI())
307 return TFI.getFrameIndexReferenceFromSP(*Asm->MF, FrameIndex, UnusedReg);
308 // For 32-bit, offsets should be relative to the end of the EH registration
309 // node. For 64-bit, it's relative to SP at the end of the prologue.
310 assert(FuncInfo.EHRegNodeEndOffset != INT_MAX);
311 int Offset = TFI.getFrameIndexReference(*Asm->MF, FrameIndex, UnusedReg);
312 Offset += FuncInfo.EHRegNodeEndOffset;
318 /// Top-level state used to represent unwind to caller
319 const int NullState = -1;
321 struct InvokeStateChange {
322 /// EH Label immediately after the last invoke in the previous state, or
323 /// nullptr if the previous state was the null state.
324 const MCSymbol *PreviousEndLabel;
326 /// EH label immediately before the first invoke in the new state, or nullptr
327 /// if the new state is the null state.
328 const MCSymbol *NewStartLabel;
330 /// State of the invoke following NewStartLabel, or NullState to indicate
331 /// the presence of calls which may unwind to caller.
335 /// Iterator that reports all the invoke state changes in a range of machine
336 /// basic blocks. Changes to the null state are reported whenever a call that
337 /// may unwind to caller is encountered. The MBB range is expected to be an
338 /// entire function or funclet, and the start and end of the range are treated
339 /// as being in the NullState even if there's not an unwind-to-caller call
340 /// before the first invoke or after the last one (i.e., the first state change
341 /// reported is the first change to something other than NullState, and a
342 /// change back to NullState is always reported at the end of iteration).
343 class InvokeStateChangeIterator {
344 InvokeStateChangeIterator(const WinEHFuncInfo &EHInfo,
345 MachineFunction::const_iterator MFI,
346 MachineFunction::const_iterator MFE,
347 MachineBasicBlock::const_iterator MBBI,
349 : EHInfo(EHInfo), MFI(MFI), MFE(MFE), MBBI(MBBI), BaseState(BaseState) {
350 LastStateChange.PreviousEndLabel = nullptr;
351 LastStateChange.NewStartLabel = nullptr;
352 LastStateChange.NewState = BaseState;
357 static iterator_range<InvokeStateChangeIterator>
358 range(const WinEHFuncInfo &EHInfo, MachineFunction::const_iterator Begin,
359 MachineFunction::const_iterator End, int BaseState = NullState) {
360 // Reject empty ranges to simplify bookkeeping by ensuring that we can get
361 // the end of the last block.
362 assert(Begin != End);
363 auto BlockBegin = Begin->begin();
364 auto BlockEnd = std::prev(End)->end();
366 InvokeStateChangeIterator(EHInfo, Begin, End, BlockBegin, BaseState),
367 InvokeStateChangeIterator(EHInfo, End, End, BlockEnd, BaseState));
371 bool operator==(const InvokeStateChangeIterator &O) const {
372 assert(BaseState == O.BaseState);
373 // Must be visiting same block.
376 // Must be visiting same isntr.
379 // At end of block/instr iteration, we can still have two distinct states:
380 // one to report the final EndLabel, and another indicating the end of the
381 // state change iteration. Check for CurrentEndLabel equality to
382 // distinguish these.
383 return CurrentEndLabel == O.CurrentEndLabel;
386 bool operator!=(const InvokeStateChangeIterator &O) const {
387 return !operator==(O);
389 InvokeStateChange &operator*() { return LastStateChange; }
390 InvokeStateChange *operator->() { return &LastStateChange; }
391 InvokeStateChangeIterator &operator++() { return scan(); }
394 InvokeStateChangeIterator &scan();
396 const WinEHFuncInfo &EHInfo;
397 const MCSymbol *CurrentEndLabel = nullptr;
398 MachineFunction::const_iterator MFI;
399 MachineFunction::const_iterator MFE;
400 MachineBasicBlock::const_iterator MBBI;
401 InvokeStateChange LastStateChange;
402 bool VisitingInvoke = false;
406 } // end anonymous namespace
408 InvokeStateChangeIterator &InvokeStateChangeIterator::scan() {
409 bool IsNewBlock = false;
410 for (; MFI != MFE; ++MFI, IsNewBlock = true) {
413 for (auto MBBE = MFI->end(); MBBI != MBBE; ++MBBI) {
414 const MachineInstr &MI = *MBBI;
415 if (!VisitingInvoke && LastStateChange.NewState != BaseState &&
416 MI.isCall() && !EHStreamer::callToNoUnwindFunction(&MI)) {
417 // Indicate a change of state to the null state. We don't have
418 // start/end EH labels handy but the caller won't expect them for
419 // null state regions.
420 LastStateChange.PreviousEndLabel = CurrentEndLabel;
421 LastStateChange.NewStartLabel = nullptr;
422 LastStateChange.NewState = BaseState;
423 CurrentEndLabel = nullptr;
424 // Don't re-visit this instr on the next scan
429 // All other state changes are at EH labels before/after invokes.
432 MCSymbol *Label = MI.getOperand(0).getMCSymbol();
433 if (Label == CurrentEndLabel) {
434 VisitingInvoke = false;
437 auto InvokeMapIter = EHInfo.LabelToStateMap.find(Label);
438 // Ignore EH labels that aren't the ones inserted before an invoke
439 if (InvokeMapIter == EHInfo.LabelToStateMap.end())
441 auto &StateAndEnd = InvokeMapIter->second;
442 int NewState = StateAndEnd.first;
443 // Keep track of the fact that we're between EH start/end labels so
444 // we know not to treat the inoke we'll see as unwinding to caller.
445 VisitingInvoke = true;
446 if (NewState == LastStateChange.NewState) {
447 // The state isn't actually changing here. Record the new end and
449 CurrentEndLabel = StateAndEnd.second;
452 // Found a state change to report
453 LastStateChange.PreviousEndLabel = CurrentEndLabel;
454 LastStateChange.NewStartLabel = Label;
455 LastStateChange.NewState = NewState;
456 // Start keeping track of the new current end
457 CurrentEndLabel = StateAndEnd.second;
458 // Don't re-visit this instr on the next scan
463 // Iteration hit the end of the block range.
464 if (LastStateChange.NewState != BaseState) {
465 // Report the end of the last new state
466 LastStateChange.PreviousEndLabel = CurrentEndLabel;
467 LastStateChange.NewStartLabel = nullptr;
468 LastStateChange.NewState = BaseState;
469 // Leave CurrentEndLabel non-null to distinguish this state from end.
470 assert(CurrentEndLabel != nullptr);
473 // We've reported all state changes and hit the end state.
474 CurrentEndLabel = nullptr;
478 /// Emit the language-specific data that __C_specific_handler expects. This
479 /// handler lives in the x64 Microsoft C runtime and allows catching or cleaning
480 /// up after faults with __try, __except, and __finally. The typeinfo values
481 /// are not really RTTI data, but pointers to filter functions that return an
482 /// integer (1, 0, or -1) indicating how to handle the exception. For __finally
483 /// blocks and other cleanups, the landing pad label is zero, and the filter
484 /// function is actually a cleanup handler with the same prototype. A catch-all
485 /// entry is modeled with a null filter function field and a non-zero landing
488 /// Possible filter function return values:
489 /// EXCEPTION_EXECUTE_HANDLER (1):
490 /// Jump to the landing pad label after cleanups.
491 /// EXCEPTION_CONTINUE_SEARCH (0):
492 /// Continue searching this table or continue unwinding.
493 /// EXCEPTION_CONTINUE_EXECUTION (-1):
494 /// Resume execution at the trapping PC.
496 /// Inferred table structure:
500 /// imagerel32 LabelStart;
501 /// imagerel32 LabelEnd;
502 /// imagerel32 FilterOrFinally; // One means catch-all.
503 /// imagerel32 LabelLPad; // Zero means __finally.
504 /// } Entries[NumEntries];
506 void WinException::emitCSpecificHandlerTable(const MachineFunction *MF) {
507 auto &OS = *Asm->OutStreamer;
508 MCContext &Ctx = Asm->OutContext;
510 const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
511 // Use the assembler to compute the number of table entries through label
512 // difference and division.
513 MCSymbol *TableBegin =
514 Ctx.createTempSymbol("lsda_begin", /*AlwaysAddSuffix=*/true);
516 Ctx.createTempSymbol("lsda_end", /*AlwaysAddSuffix=*/true);
517 const MCExpr *LabelDiff = getOffset(TableEnd, TableBegin);
518 const MCExpr *EntrySize = MCConstantExpr::create(16, Ctx);
519 const MCExpr *EntryCount = MCBinaryExpr::createDiv(LabelDiff, EntrySize, Ctx);
520 OS.EmitValue(EntryCount, 4);
522 OS.EmitLabel(TableBegin);
524 // Iterate over all the invoke try ranges. Unlike MSVC, LLVM currently only
525 // models exceptions from invokes. LLVM also allows arbitrary reordering of
526 // the code, so our tables end up looking a bit different. Rather than
527 // trying to match MSVC's tables exactly, we emit a denormalized table. For
528 // each range of invokes in the same state, we emit table entries for all
529 // the actions that would be taken in that state. This means our tables are
530 // slightly bigger, which is OK.
531 const MCSymbol *LastStartLabel = nullptr;
532 int LastEHState = -1;
533 // Break out before we enter into a finally funclet.
534 // FIXME: We need to emit separate EH tables for cleanups.
535 MachineFunction::const_iterator End = MF->end();
536 MachineFunction::const_iterator Stop = std::next(MF->begin());
537 while (Stop != End && !Stop->isEHFuncletEntry())
539 for (const auto &StateChange :
540 InvokeStateChangeIterator::range(FuncInfo, MF->begin(), Stop)) {
541 // Emit all the actions for the state we just transitioned out of
542 // if it was not the null state
543 if (LastEHState != -1)
544 emitSEHActionsForRange(FuncInfo, LastStartLabel,
545 StateChange.PreviousEndLabel, LastEHState);
546 LastStartLabel = StateChange.NewStartLabel;
547 LastEHState = StateChange.NewState;
550 OS.EmitLabel(TableEnd);
553 void WinException::emitSEHActionsForRange(const WinEHFuncInfo &FuncInfo,
554 const MCSymbol *BeginLabel,
555 const MCSymbol *EndLabel, int State) {
556 auto &OS = *Asm->OutStreamer;
557 MCContext &Ctx = Asm->OutContext;
559 assert(BeginLabel && EndLabel);
560 while (State != -1) {
561 const SEHUnwindMapEntry &UME = FuncInfo.SEHUnwindMap[State];
562 const MCExpr *FilterOrFinally;
563 const MCExpr *ExceptOrNull;
564 auto *Handler = UME.Handler.get<MachineBasicBlock *>();
566 FilterOrFinally = create32bitRef(getMCSymbolForMBB(Asm, Handler));
567 ExceptOrNull = MCConstantExpr::create(0, Ctx);
569 // For an except, the filter can be 1 (catch-all) or a function
571 FilterOrFinally = UME.Filter ? create32bitRef(UME.Filter)
572 : MCConstantExpr::create(1, Ctx);
573 ExceptOrNull = create32bitRef(Handler->getSymbol());
576 OS.EmitValue(getLabelPlusOne(BeginLabel), 4);
577 OS.EmitValue(getLabelPlusOne(EndLabel), 4);
578 OS.EmitValue(FilterOrFinally, 4);
579 OS.EmitValue(ExceptOrNull, 4);
581 assert(UME.ToState < State && "states should decrease");
586 void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
587 const Function *F = MF->getFunction();
588 auto &OS = *Asm->OutStreamer;
589 const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
591 StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
593 SmallVector<std::pair<const MCExpr *, int>, 4> IPToStateTable;
594 MCSymbol *FuncInfoXData = nullptr;
595 if (shouldEmitPersonality) {
596 // If we're 64-bit, emit a pointer to the C++ EH data, and build a map from
597 // IPs to state numbers.
599 Asm->OutContext.getOrCreateSymbol(Twine("$cppxdata$", FuncLinkageName));
600 computeIP2StateTable(MF, FuncInfo, IPToStateTable);
602 FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(FuncLinkageName);
605 int UnwindHelpOffset = 0;
606 if (Asm->MAI->usesWindowsCFI())
608 getFrameIndexOffset(FuncInfo.UnwindHelpFrameIdx, FuncInfo);
610 MCSymbol *UnwindMapXData = nullptr;
611 MCSymbol *TryBlockMapXData = nullptr;
612 MCSymbol *IPToStateXData = nullptr;
613 if (!FuncInfo.CxxUnwindMap.empty())
614 UnwindMapXData = Asm->OutContext.getOrCreateSymbol(
615 Twine("$stateUnwindMap$", FuncLinkageName));
616 if (!FuncInfo.TryBlockMap.empty())
618 Asm->OutContext.getOrCreateSymbol(Twine("$tryMap$", FuncLinkageName));
619 if (!IPToStateTable.empty())
621 Asm->OutContext.getOrCreateSymbol(Twine("$ip2state$", FuncLinkageName));
624 // uint32_t MagicNumber
626 // UnwindMapEntry *UnwindMap;
627 // uint32_t NumTryBlocks;
628 // TryBlockMapEntry *TryBlockMap;
629 // uint32_t IPMapEntries; // always 0 for x86
630 // IPToStateMapEntry *IPToStateMap; // always 0 for x86
631 // uint32_t UnwindHelp; // non-x86 only
632 // ESTypeList *ESTypeList;
635 // EHFlags & 1 -> Synchronous exceptions only, no async exceptions.
636 // EHFlags & 2 -> ???
637 // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue.
638 OS.EmitValueToAlignment(4);
639 OS.EmitLabel(FuncInfoXData);
640 OS.EmitIntValue(0x19930522, 4); // MagicNumber
641 OS.EmitIntValue(FuncInfo.CxxUnwindMap.size(), 4); // MaxState
642 OS.EmitValue(create32bitRef(UnwindMapXData), 4); // UnwindMap
643 OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4); // NumTryBlocks
644 OS.EmitValue(create32bitRef(TryBlockMapXData), 4); // TryBlockMap
645 OS.EmitIntValue(IPToStateTable.size(), 4); // IPMapEntries
646 OS.EmitValue(create32bitRef(IPToStateXData), 4); // IPToStateMap
647 if (Asm->MAI->usesWindowsCFI())
648 OS.EmitIntValue(UnwindHelpOffset, 4); // UnwindHelp
649 OS.EmitIntValue(0, 4); // ESTypeList
650 OS.EmitIntValue(1, 4); // EHFlags
656 if (UnwindMapXData) {
657 OS.EmitLabel(UnwindMapXData);
658 for (const CxxUnwindMapEntry &UME : FuncInfo.CxxUnwindMap) {
659 MCSymbol *CleanupSym =
660 getMCSymbolForMBB(Asm, UME.Cleanup.dyn_cast<MachineBasicBlock *>());
661 OS.EmitIntValue(UME.ToState, 4); // ToState
662 OS.EmitValue(create32bitRef(CleanupSym), 4); // Action
669 // int32_t CatchHigh;
670 // int32_t NumCatches;
671 // HandlerType *HandlerArray;
673 if (TryBlockMapXData) {
674 OS.EmitLabel(TryBlockMapXData);
675 SmallVector<MCSymbol *, 1> HandlerMaps;
676 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
677 const WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
679 MCSymbol *HandlerMapXData = nullptr;
680 if (!TBME.HandlerArray.empty())
682 Asm->OutContext.getOrCreateSymbol(Twine("$handlerMap$")
685 .concat(FuncLinkageName));
686 HandlerMaps.push_back(HandlerMapXData);
688 // TBMEs should form intervals.
689 assert(0 <= TBME.TryLow && "bad trymap interval");
690 assert(TBME.TryLow <= TBME.TryHigh && "bad trymap interval");
691 assert(TBME.TryHigh < TBME.CatchHigh && "bad trymap interval");
692 assert(TBME.CatchHigh < int(FuncInfo.CxxUnwindMap.size()) &&
693 "bad trymap interval");
695 OS.EmitIntValue(TBME.TryLow, 4); // TryLow
696 OS.EmitIntValue(TBME.TryHigh, 4); // TryHigh
697 OS.EmitIntValue(TBME.CatchHigh, 4); // CatchHigh
698 OS.EmitIntValue(TBME.HandlerArray.size(), 4); // NumCatches
699 OS.EmitValue(create32bitRef(HandlerMapXData), 4); // HandlerArray
702 // All funclets use the same parent frame offset currently.
703 unsigned ParentFrameOffset = 0;
704 if (shouldEmitPersonality) {
705 const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
706 ParentFrameOffset = TFI->getWinEHParentFrameOffset(*MF);
709 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
710 const WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
711 MCSymbol *HandlerMapXData = HandlerMaps[I];
712 if (!HandlerMapXData)
715 // int32_t Adjectives;
716 // TypeDescriptor *Type;
717 // int32_t CatchObjOffset;
718 // void (*Handler)();
719 // int32_t ParentFrameOffset; // x64 only
721 OS.EmitLabel(HandlerMapXData);
722 for (const WinEHHandlerType &HT : TBME.HandlerArray) {
723 // Get the frame escape label with the offset of the catch object. If
724 // the index is INT_MAX, then there is no catch object, and we should
725 // emit an offset of zero, indicating that no copy will occur.
726 const MCExpr *FrameAllocOffsetRef = nullptr;
727 if (HT.CatchObj.FrameIndex != INT_MAX) {
728 int Offset = getFrameIndexOffset(HT.CatchObj.FrameIndex, FuncInfo);
729 FrameAllocOffsetRef = MCConstantExpr::create(Offset, Asm->OutContext);
731 FrameAllocOffsetRef = MCConstantExpr::create(0, Asm->OutContext);
734 MCSymbol *HandlerSym =
735 getMCSymbolForMBB(Asm, HT.Handler.dyn_cast<MachineBasicBlock *>());
737 OS.EmitIntValue(HT.Adjectives, 4); // Adjectives
738 OS.EmitValue(create32bitRef(HT.TypeDescriptor), 4); // Type
739 OS.EmitValue(FrameAllocOffsetRef, 4); // CatchObjOffset
740 OS.EmitValue(create32bitRef(HandlerSym), 4); // Handler
741 if (shouldEmitPersonality)
742 OS.EmitIntValue(ParentFrameOffset, 4); // ParentFrameOffset
747 // IPToStateMapEntry {
751 if (IPToStateXData) {
752 OS.EmitLabel(IPToStateXData);
753 for (auto &IPStatePair : IPToStateTable) {
754 OS.EmitValue(IPStatePair.first, 4); // IP
755 OS.EmitIntValue(IPStatePair.second, 4); // State
760 void WinException::computeIP2StateTable(
761 const MachineFunction *MF, const WinEHFuncInfo &FuncInfo,
762 SmallVectorImpl<std::pair<const MCExpr *, int>> &IPToStateTable) {
764 for (MachineFunction::const_iterator FuncletStart = MF->begin(),
765 FuncletEnd = MF->begin(),
767 FuncletStart != End; FuncletStart = FuncletEnd) {
768 // Find the end of the funclet
769 while (++FuncletEnd != End) {
770 if (FuncletEnd->isEHFuncletEntry()) {
775 // Don't emit ip2state entries for cleanup funclets. Any interesting
776 // exceptional actions in cleanups must be handled in a separate IR
778 if (FuncletStart->isCleanupFuncletEntry())
781 MCSymbol *StartLabel;
783 if (FuncletStart == MF->begin()) {
784 BaseState = NullState;
785 StartLabel = Asm->getFunctionBegin();
788 cast<FuncletPadInst>(FuncletStart->getBasicBlock()->getFirstNonPHI());
789 assert(FuncInfo.FuncletBaseStateMap.count(FuncletPad) != 0);
790 BaseState = FuncInfo.FuncletBaseStateMap.find(FuncletPad)->second;
791 StartLabel = getMCSymbolForMBB(Asm, &*FuncletStart);
793 assert(StartLabel && "need local function start label");
794 IPToStateTable.push_back(
795 std::make_pair(create32bitRef(StartLabel), BaseState));
797 for (const auto &StateChange : InvokeStateChangeIterator::range(
798 FuncInfo, FuncletStart, FuncletEnd, BaseState)) {
799 // Compute the label to report as the start of this entry; use the EH
800 // start label for the invoke if we have one, otherwise (this is a call
801 // which may unwind to our caller and does not have an EH start label, so)
802 // use the previous end label.
803 const MCSymbol *ChangeLabel = StateChange.NewStartLabel;
805 ChangeLabel = StateChange.PreviousEndLabel;
806 // Emit an entry indicating that PCs after 'Label' have this EH state.
807 IPToStateTable.push_back(
808 std::make_pair(getLabelPlusOne(ChangeLabel), StateChange.NewState));
809 // FIXME: assert that NewState is between CatchLow and CatchHigh.
814 void WinException::emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo,
815 StringRef FLinkageName) {
816 // Outlined helpers called by the EH runtime need to know the offset of the EH
817 // registration in order to recover the parent frame pointer. Now that we know
818 // we've code generated the parent, we can emit the label assignment that
819 // those helpers use to get the offset of the registration node.
820 MCContext &Ctx = Asm->OutContext;
821 MCSymbol *ParentFrameOffset =
822 Ctx.getOrCreateParentFrameOffsetSymbol(FLinkageName);
824 const TargetFrameLowering *TFI = Asm->MF->getSubtarget().getFrameLowering();
825 int64_t Offset = TFI->getFrameIndexReference(
826 *Asm->MF, FuncInfo.EHRegNodeFrameIndex, UnusedReg);
827 const MCExpr *MCOffset = MCConstantExpr::create(Offset, Ctx);
828 Asm->OutStreamer->EmitAssignment(ParentFrameOffset, MCOffset);
831 /// Emit the language-specific data that _except_handler3 and 4 expect. This is
832 /// functionally equivalent to the __C_specific_handler table, except it is
833 /// indexed by state number instead of IP.
834 void WinException::emitExceptHandlerTable(const MachineFunction *MF) {
835 MCStreamer &OS = *Asm->OutStreamer;
836 const Function *F = MF->getFunction();
837 StringRef FLinkageName = GlobalValue::getRealLinkageName(F->getName());
839 const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
840 emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
842 // Emit the __ehtable label that we use for llvm.x86.seh.lsda.
843 MCSymbol *LSDALabel = Asm->OutContext.getOrCreateLSDASymbol(FLinkageName);
844 OS.EmitValueToAlignment(4);
845 OS.EmitLabel(LSDALabel);
847 const Function *Per =
848 dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
849 StringRef PerName = Per->getName();
851 if (PerName == "_except_handler4") {
852 // The LSDA for _except_handler4 starts with this struct, followed by the
855 // struct EH4ScopeTable {
856 // int32_t GSCookieOffset;
857 // int32_t GSCookieXOROffset;
858 // int32_t EHCookieOffset;
859 // int32_t EHCookieXOROffset;
860 // ScopeTableEntry ScopeRecord[];
863 // Only the EHCookieOffset field appears to vary, and it appears to be the
864 // offset from the final saved SP value to the retaddr.
865 OS.EmitIntValue(-2, 4);
866 OS.EmitIntValue(0, 4);
868 OS.EmitIntValue(9999, 4);
869 OS.EmitIntValue(0, 4);
873 assert(!FuncInfo.SEHUnwindMap.empty());
874 for (const SEHUnwindMapEntry &UME : FuncInfo.SEHUnwindMap) {
875 MCSymbol *ExceptOrFinally =
876 UME.Handler.get<MachineBasicBlock *>()->getSymbol();
877 // -1 is usually the base state for "unwind to caller", but for
878 // _except_handler4 it's -2. Do that replacement here if necessary.
879 int ToState = UME.ToState == -1 ? BaseState : UME.ToState;
880 OS.EmitIntValue(ToState, 4); // ToState
881 OS.EmitValue(create32bitRef(UME.Filter), 4); // Filter
882 OS.EmitValue(create32bitRef(ExceptOrFinally), 4); // Except/Finally
886 static int getRank(const WinEHFuncInfo &FuncInfo, int State) {
888 while (State != -1) {
890 State = FuncInfo.ClrEHUnwindMap[State].Parent;
895 static int getAncestor(const WinEHFuncInfo &FuncInfo, int Left, int Right) {
896 int LeftRank = getRank(FuncInfo, Left);
897 int RightRank = getRank(FuncInfo, Right);
899 while (LeftRank < RightRank) {
900 Right = FuncInfo.ClrEHUnwindMap[Right].Parent;
904 while (RightRank < LeftRank) {
905 Left = FuncInfo.ClrEHUnwindMap[Left].Parent;
909 while (Left != Right) {
910 Left = FuncInfo.ClrEHUnwindMap[Left].Parent;
911 Right = FuncInfo.ClrEHUnwindMap[Right].Parent;
917 void WinException::emitCLRExceptionTable(const MachineFunction *MF) {
918 // CLR EH "states" are really just IDs that identify handlers/funclets;
919 // states, handlers, and funclets all have 1:1 mappings between them, and a
920 // handler/funclet's "state" is its index in the ClrEHUnwindMap.
921 MCStreamer &OS = *Asm->OutStreamer;
922 const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
923 MCSymbol *FuncBeginSym = Asm->getFunctionBegin();
924 MCSymbol *FuncEndSym = Asm->getFunctionEnd();
926 // A ClrClause describes a protected region.
928 const MCSymbol *StartLabel; // Start of protected region
929 const MCSymbol *EndLabel; // End of protected region
930 int State; // Index of handler protecting the protected region
931 int EnclosingState; // Index of funclet enclosing the protected region
933 SmallVector<ClrClause, 8> Clauses;
935 // Build a map from handler MBBs to their corresponding states (i.e. their
936 // indices in the ClrEHUnwindMap).
937 int NumStates = FuncInfo.ClrEHUnwindMap.size();
938 assert(NumStates > 0 && "Don't need exception table!");
939 DenseMap<const MachineBasicBlock *, int> HandlerStates;
940 for (int State = 0; State < NumStates; ++State) {
941 MachineBasicBlock *HandlerBlock =
942 FuncInfo.ClrEHUnwindMap[State].Handler.get<MachineBasicBlock *>();
943 HandlerStates[HandlerBlock] = State;
944 // Use this loop through all handlers to verify our assumption (used in
945 // the MinEnclosingState computation) that ancestors have lower state
946 // numbers than their descendants.
947 assert(FuncInfo.ClrEHUnwindMap[State].Parent < State &&
948 "ill-formed state numbering");
950 // Map the main function to the NullState.
951 HandlerStates[&MF->front()] = NullState;
953 // Write out a sentinel indicating the end of the standard (Windows) xdata
954 // and the start of the additional (CLR) info.
955 OS.EmitIntValue(0xffffffff, 4);
956 // Write out the number of funclets
957 OS.EmitIntValue(NumStates, 4);
959 // Walk the machine blocks/instrs, computing and emitting a few things:
960 // 1. Emit a list of the offsets to each handler entry, in lexical order.
961 // 2. Compute a map (EndSymbolMap) from each funclet to the symbol at its end.
962 // 3. Compute the list of ClrClauses, in the required order (inner before
963 // outer, earlier before later; the order by which a forward scan with
964 // early termination will find the innermost enclosing clause covering
966 // 4. A map (MinClauseMap) from each handler index to the index of the
967 // outermost funclet/function which contains a try clause targeting the
968 // key handler. This will be used to determine IsDuplicate-ness when
969 // emitting ClrClauses. The NullState value is used to indicate that the
970 // top-level function contains a try clause targeting the key handler.
971 // HandlerStack is a stack of (PendingStartLabel, PendingState) pairs for
972 // try regions we entered before entering the PendingState try but which
973 // we haven't yet exited.
974 SmallVector<std::pair<const MCSymbol *, int>, 4> HandlerStack;
975 // EndSymbolMap and MinClauseMap are maps described above.
976 std::unique_ptr<MCSymbol *[]> EndSymbolMap(new MCSymbol *[NumStates]);
977 SmallVector<int, 4> MinClauseMap((size_t)NumStates, NumStates);
979 // Visit the root function and each funclet.
981 for (MachineFunction::const_iterator FuncletStart = MF->begin(),
982 FuncletEnd = MF->begin(),
984 FuncletStart != End; FuncletStart = FuncletEnd) {
985 int FuncletState = HandlerStates[&*FuncletStart];
986 // Find the end of the funclet
987 MCSymbol *EndSymbol = FuncEndSym;
988 while (++FuncletEnd != End) {
989 if (FuncletEnd->isEHFuncletEntry()) {
990 EndSymbol = getMCSymbolForMBB(Asm, &*FuncletEnd);
994 // Emit the function/funclet end and, if this is a funclet (and not the
995 // root function), record it in the EndSymbolMap.
996 OS.EmitValue(getOffset(EndSymbol, FuncBeginSym), 4);
997 if (FuncletState != NullState) {
998 // Record the end of the handler.
999 EndSymbolMap[FuncletState] = EndSymbol;
1002 // Walk the state changes in this function/funclet and compute its clauses.
1003 // Funclets always start in the null state.
1004 const MCSymbol *CurrentStartLabel = nullptr;
1005 int CurrentState = NullState;
1006 assert(HandlerStack.empty());
1007 for (const auto &StateChange :
1008 InvokeStateChangeIterator::range(FuncInfo, FuncletStart, FuncletEnd)) {
1009 // Close any try regions we're not still under
1011 getAncestor(FuncInfo, CurrentState, StateChange.NewState);
1012 while (CurrentState != AncestorState) {
1013 assert(CurrentState != NullState && "Failed to find ancestor!");
1014 // Close the pending clause
1015 Clauses.push_back({CurrentStartLabel, StateChange.PreviousEndLabel,
1016 CurrentState, FuncletState});
1017 // Now the parent handler is current
1018 CurrentState = FuncInfo.ClrEHUnwindMap[CurrentState].Parent;
1019 // Pop the new start label from the handler stack if we've exited all
1020 // descendants of the corresponding handler.
1021 if (HandlerStack.back().second == CurrentState)
1022 CurrentStartLabel = HandlerStack.pop_back_val().first;
1025 if (StateChange.NewState != CurrentState) {
1026 // For each clause we're starting, update the MinClauseMap so we can
1027 // know which is the topmost funclet containing a clause targeting
1029 for (int EnteredState = StateChange.NewState;
1030 EnteredState != CurrentState;
1031 EnteredState = FuncInfo.ClrEHUnwindMap[EnteredState].Parent) {
1032 int &MinEnclosingState = MinClauseMap[EnteredState];
1033 if (FuncletState < MinEnclosingState)
1034 MinEnclosingState = FuncletState;
1036 // Save the previous current start/label on the stack and update to
1037 // the newly-current start/state.
1038 HandlerStack.emplace_back(CurrentStartLabel, CurrentState);
1039 CurrentStartLabel = StateChange.NewStartLabel;
1040 CurrentState = StateChange.NewState;
1043 assert(HandlerStack.empty());
1046 // Now emit the clause info, starting with the number of clauses.
1047 OS.EmitIntValue(Clauses.size(), 4);
1048 for (ClrClause &Clause : Clauses) {
1049 // Emit a CORINFO_EH_CLAUSE :
1051 struct CORINFO_EH_CLAUSE
1053 CORINFO_EH_CLAUSE_FLAGS Flags; // actually a CorExceptionFlag
1055 DWORD TryLength; // actually TryEndOffset
1056 DWORD HandlerOffset;
1057 DWORD HandlerLength; // actually HandlerEndOffset
1060 DWORD ClassToken; // use for catch clauses
1061 DWORD FilterOffset; // use for filter clauses
1065 enum CORINFO_EH_CLAUSE_FLAGS
1067 CORINFO_EH_CLAUSE_NONE = 0,
1068 CORINFO_EH_CLAUSE_FILTER = 0x0001, // This clause is for a filter
1069 CORINFO_EH_CLAUSE_FINALLY = 0x0002, // This clause is a finally clause
1070 CORINFO_EH_CLAUSE_FAULT = 0x0004, // This clause is a fault clause
1072 typedef enum CorExceptionFlag
1074 COR_ILEXCEPTION_CLAUSE_NONE,
1075 COR_ILEXCEPTION_CLAUSE_FILTER = 0x0001, // This is a filter clause
1076 COR_ILEXCEPTION_CLAUSE_FINALLY = 0x0002, // This is a finally clause
1077 COR_ILEXCEPTION_CLAUSE_FAULT = 0x0004, // This is a fault clause
1078 COR_ILEXCEPTION_CLAUSE_DUPLICATED = 0x0008, // duplicated clause. This
1079 // clause was duplicated
1080 // to a funclet which was
1081 // pulled out of line
1084 // Add 1 to the start/end of the EH clause; the IP associated with a
1085 // call when the runtime does its scan is the IP of the next instruction
1086 // (the one to which control will return after the call), so we need
1087 // to add 1 to the end of the clause to cover that offset. We also add
1088 // 1 to the start of the clause to make sure that the ranges reported
1089 // for all clauses are disjoint. Note that we'll need some additional
1090 // logic when machine traps are supported, since in that case the IP
1091 // that the runtime uses is the offset of the faulting instruction
1092 // itself; if such an instruction immediately follows a call but the
1093 // two belong to different clauses, we'll need to insert a nop between
1094 // them so the runtime can distinguish the point to which the call will
1095 // return from the point at which the fault occurs.
1097 const MCExpr *ClauseBegin =
1098 getOffsetPlusOne(Clause.StartLabel, FuncBeginSym);
1099 const MCExpr *ClauseEnd = getOffsetPlusOne(Clause.EndLabel, FuncBeginSym);
1101 const ClrEHUnwindMapEntry &Entry = FuncInfo.ClrEHUnwindMap[Clause.State];
1102 MachineBasicBlock *HandlerBlock = Entry.Handler.get<MachineBasicBlock *>();
1103 MCSymbol *BeginSym = getMCSymbolForMBB(Asm, HandlerBlock);
1104 const MCExpr *HandlerBegin = getOffset(BeginSym, FuncBeginSym);
1105 MCSymbol *EndSym = EndSymbolMap[Clause.State];
1106 const MCExpr *HandlerEnd = getOffset(EndSym, FuncBeginSym);
1109 switch (Entry.HandlerType) {
1110 case ClrHandlerType::Catch:
1111 // Leaving bits 0-2 clear indicates catch.
1113 case ClrHandlerType::Filter:
1116 case ClrHandlerType::Finally:
1119 case ClrHandlerType::Fault:
1123 if (Clause.EnclosingState != MinClauseMap[Clause.State]) {
1124 // This is a "duplicate" clause; the handler needs to be entered from a
1125 // frame above the one holding the invoke.
1126 assert(Clause.EnclosingState > MinClauseMap[Clause.State]);
1129 OS.EmitIntValue(Flags, 4);
1131 // Write the clause start/end
1132 OS.EmitValue(ClauseBegin, 4);
1133 OS.EmitValue(ClauseEnd, 4);
1135 // Write out the handler start/end
1136 OS.EmitValue(HandlerBegin, 4);
1137 OS.EmitValue(HandlerEnd, 4);
1139 // Write out the type token or filter offset
1140 assert(Entry.HandlerType != ClrHandlerType::Filter && "NYI: filters");
1141 OS.EmitIntValue(Entry.TypeToken, 4);