1 //===-- CodeGen/AsmPrinter/WinException.cpp - Dwarf Exception Impl ------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains support for writing Win64 exception info into asm files.
12 //===----------------------------------------------------------------------===//
14 #include "WinException.h"
15 #include "llvm/ADT/SmallString.h"
16 #include "llvm/ADT/StringExtras.h"
17 #include "llvm/ADT/Twine.h"
18 #include "llvm/CodeGen/AsmPrinter.h"
19 #include "llvm/CodeGen/MachineFrameInfo.h"
20 #include "llvm/CodeGen/MachineFunction.h"
21 #include "llvm/CodeGen/MachineModuleInfo.h"
22 #include "llvm/CodeGen/WinEHFuncInfo.h"
23 #include "llvm/IR/DataLayout.h"
24 #include "llvm/IR/Mangler.h"
25 #include "llvm/IR/Module.h"
26 #include "llvm/MC/MCAsmInfo.h"
27 #include "llvm/MC/MCContext.h"
28 #include "llvm/MC/MCExpr.h"
29 #include "llvm/MC/MCSection.h"
30 #include "llvm/MC/MCStreamer.h"
31 #include "llvm/MC/MCSymbol.h"
32 #include "llvm/MC/MCWin64EH.h"
33 #include "llvm/Support/COFF.h"
34 #include "llvm/Support/Dwarf.h"
35 #include "llvm/Support/ErrorHandling.h"
36 #include "llvm/Support/FormattedStream.h"
37 #include "llvm/Target/TargetFrameLowering.h"
38 #include "llvm/Target/TargetLoweringObjectFile.h"
39 #include "llvm/Target/TargetOptions.h"
40 #include "llvm/Target/TargetRegisterInfo.h"
43 WinException::WinException(AsmPrinter *A) : EHStreamer(A) {
44 // MSVC's EH tables are always composed of 32-bit words. All known 64-bit
45 // platforms use an imagerel32 relocation to refer to symbols.
46 useImageRel32 = (A->getDataLayout().getPointerSizeInBits() == 64);
49 WinException::~WinException() {}
51 /// endModule - Emit all exception information that should come after the
53 void WinException::endModule() {
54 auto &OS = *Asm->OutStreamer;
55 const Module *M = MMI->getModule();
56 for (const Function &F : *M)
57 if (F.hasFnAttribute("safeseh"))
58 OS.EmitCOFFSafeSEH(Asm->getSymbol(&F));
61 void WinException::beginFunction(const MachineFunction *MF) {
62 shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
64 // If any landing pads survive, we need an EH table.
65 bool hasLandingPads = !MMI->getLandingPads().empty();
66 bool hasEHFunclets = MMI->hasEHFunclets();
68 const Function *F = MF->getFunction();
69 const Function *ParentF = MMI->getWinEHParent(F);
71 shouldEmitMoves = Asm->needsSEHMoves();
73 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
74 unsigned PerEncoding = TLOF.getPersonalityEncoding();
75 const Function *Per = nullptr;
76 if (F->hasPersonalityFn())
77 Per = dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
79 bool forceEmitPersonality =
80 F->hasPersonalityFn() && !isNoOpWithoutInvoke(classifyEHPersonality(Per)) &&
81 F->needsUnwindTableEntry();
83 shouldEmitPersonality =
84 forceEmitPersonality || ((hasLandingPads || hasEHFunclets) &&
85 PerEncoding != dwarf::DW_EH_PE_omit && Per);
87 unsigned LSDAEncoding = TLOF.getLSDAEncoding();
88 shouldEmitLSDA = shouldEmitPersonality &&
89 LSDAEncoding != dwarf::DW_EH_PE_omit;
91 // If we're not using CFI, we don't want the CFI or the personality, but we
92 // might want EH tables if we had EH pads.
93 // FIXME: If WinEHPrepare outlined something, we should emit the LSDA. Remove
94 // this once WinEHPrepare stops doing that.
95 if (!Asm->MAI->usesWindowsCFI()) {
97 hasEHFunclets || (F->hasFnAttribute("wineh-parent") && F == ParentF);
98 shouldEmitPersonality = false;
102 beginFunclet(MF->front(), Asm->CurrentFnSym);
105 /// endFunction - Gather and emit post-function exception information.
107 void WinException::endFunction(const MachineFunction *MF) {
108 if (!shouldEmitPersonality && !shouldEmitMoves && !shouldEmitLSDA)
111 const Function *F = MF->getFunction();
112 EHPersonality Per = EHPersonality::Unknown;
113 if (F->hasPersonalityFn())
114 Per = classifyEHPersonality(F->getPersonalityFn());
116 // Get rid of any dead landing pads if we're not using a Windows EH scheme. In
117 // Windows EH schemes, the landing pad is not actually reachable. It only
118 // exists so that we can emit the right table data.
119 if (!isMSVCEHPersonality(Per))
120 MMI->TidyLandingPads();
124 if (shouldEmitPersonality || shouldEmitLSDA) {
125 Asm->OutStreamer->PushSection();
127 // Just switch sections to the right xdata section. This use of CurrentFnSym
128 // assumes that we only emit the LSDA when ending the parent function.
129 MCSection *XData = WinEH::UnwindEmitter::getXDataSection(Asm->CurrentFnSym,
131 Asm->OutStreamer->SwitchSection(XData);
133 // Emit the tables appropriate to the personality function in use. If we
134 // don't recognize the personality, assume it uses an Itanium-style LSDA.
135 if (Per == EHPersonality::MSVC_Win64SEH)
136 emitCSpecificHandlerTable(MF);
137 else if (Per == EHPersonality::MSVC_X86SEH)
138 emitExceptHandlerTable(MF);
139 else if (Per == EHPersonality::MSVC_CXX)
140 emitCXXFrameHandler3Table(MF);
142 emitExceptionTable();
144 Asm->OutStreamer->PopSection();
148 /// Retreive the MCSymbol for a GlobalValue or MachineBasicBlock. GlobalValues
149 /// are used in the old WinEH scheme, and they will be removed eventually.
150 static MCSymbol *getMCSymbolForMBBOrGV(AsmPrinter *Asm, ValueOrMBB Handler) {
153 if (Handler.is<const MachineBasicBlock *>()) {
154 auto *MBB = Handler.get<const MachineBasicBlock *>();
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");
168 return Asm->getSymbol(cast<GlobalValue>(Handler.get<const Value *>()));
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 = getMCSymbolForMBBOrGV(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 this is a C++ catch funclet (or the parent function),
241 // emit a reference to the LSDA for the parent function.
242 if (Per == EHPersonality::MSVC_CXX && shouldEmitPersonality &&
243 !CurrentFuncletEntry->isCleanupFuncletEntry()) {
244 StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
245 MCSymbol *FuncInfoXData = Asm->OutContext.getOrCreateSymbol(
246 Twine("$cppxdata$", FuncLinkageName));
247 Asm->OutStreamer->EmitValue(create32bitRef(FuncInfoXData), 4);
250 // Switch back to the previous section now that we are done writing to
252 Asm->OutStreamer->PopSection();
254 // Emit a .seh_endproc directive to mark the end of the function.
255 Asm->OutStreamer->EmitWinCFIEndProc();
258 // Let's make sure we don't try to end the same funclet twice.
259 CurrentFuncletEntry = nullptr;
262 const MCExpr *WinException::create32bitRef(const MCSymbol *Value) {
264 return MCConstantExpr::create(0, Asm->OutContext);
265 return MCSymbolRefExpr::create(Value, useImageRel32
266 ? MCSymbolRefExpr::VK_COFF_IMGREL32
267 : MCSymbolRefExpr::VK_None,
271 const MCExpr *WinException::create32bitRef(const Value *V) {
273 return MCConstantExpr::create(0, Asm->OutContext);
274 // FIXME: Delete the GlobalValue case once the new IR is fully functional.
275 if (const auto *GV = dyn_cast<GlobalValue>(V))
276 return create32bitRef(Asm->getSymbol(GV));
277 return create32bitRef(MMI->getAddrLabelSymbol(cast<BasicBlock>(V)));
280 const MCExpr *WinException::getLabelPlusOne(MCSymbol *Label) {
281 return MCBinaryExpr::createAdd(create32bitRef(Label),
282 MCConstantExpr::create(1, Asm->OutContext),
286 /// Emit the language-specific data that __C_specific_handler expects. This
287 /// handler lives in the x64 Microsoft C runtime and allows catching or cleaning
288 /// up after faults with __try, __except, and __finally. The typeinfo values
289 /// are not really RTTI data, but pointers to filter functions that return an
290 /// integer (1, 0, or -1) indicating how to handle the exception. For __finally
291 /// blocks and other cleanups, the landing pad label is zero, and the filter
292 /// function is actually a cleanup handler with the same prototype. A catch-all
293 /// entry is modeled with a null filter function field and a non-zero landing
296 /// Possible filter function return values:
297 /// EXCEPTION_EXECUTE_HANDLER (1):
298 /// Jump to the landing pad label after cleanups.
299 /// EXCEPTION_CONTINUE_SEARCH (0):
300 /// Continue searching this table or continue unwinding.
301 /// EXCEPTION_CONTINUE_EXECUTION (-1):
302 /// Resume execution at the trapping PC.
304 /// Inferred table structure:
308 /// imagerel32 LabelStart;
309 /// imagerel32 LabelEnd;
310 /// imagerel32 FilterOrFinally; // One means catch-all.
311 /// imagerel32 LabelLPad; // Zero means __finally.
312 /// } Entries[NumEntries];
314 void WinException::emitCSpecificHandlerTable(const MachineFunction *MF) {
315 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
317 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(MF->getFunction());
318 if (!FuncInfo.SEHUnwindMap.empty())
319 report_fatal_error("x64 SEH tables not yet implemented");
321 // Simplifying assumptions for first implementation:
322 // - Cleanups are not implemented.
323 // - Filters are not implemented.
325 // The Itanium LSDA table sorts similar landing pads together to simplify the
326 // actions table, but we don't need that.
327 SmallVector<const LandingPadInfo *, 64> LandingPads;
328 LandingPads.reserve(PadInfos.size());
329 for (const auto &LP : PadInfos)
330 LandingPads.push_back(&LP);
332 // Compute label ranges for call sites as we would for the Itanium LSDA, but
333 // use an all zero action table because we aren't using these actions.
334 SmallVector<unsigned, 64> FirstActions;
335 FirstActions.resize(LandingPads.size());
336 SmallVector<CallSiteEntry, 64> CallSites;
337 computeCallSiteTable(CallSites, LandingPads, FirstActions);
339 MCSymbol *EHFuncBeginSym = Asm->getFunctionBegin();
340 MCSymbol *EHFuncEndSym = Asm->getFunctionEnd();
342 // Emit the number of table entries.
343 unsigned NumEntries = 0;
344 for (const CallSiteEntry &CSE : CallSites) {
346 continue; // Ignore gaps.
347 NumEntries += CSE.LPad->SEHHandlers.size();
349 Asm->OutStreamer->EmitIntValue(NumEntries, 4);
351 // If there are no actions, we don't need to iterate again.
355 // Emit the four-label records for each call site entry. The table has to be
356 // sorted in layout order, and the call sites should already be sorted.
357 for (const CallSiteEntry &CSE : CallSites) {
358 // Ignore gaps. Unlike the Itanium model, unwinding through a frame without
359 // an EH table entry will propagate the exception rather than terminating
363 const LandingPadInfo *LPad = CSE.LPad;
365 // Compute the label range. We may reuse the function begin and end labels
366 // rather than forming new ones.
367 const MCExpr *Begin =
368 create32bitRef(CSE.BeginLabel ? CSE.BeginLabel : EHFuncBeginSym);
371 // The interval is half-open, so we have to add one to include the return
372 // address of the last invoke in the range.
373 End = getLabelPlusOne(CSE.EndLabel);
375 End = create32bitRef(EHFuncEndSym);
378 // Emit an entry for each action.
379 for (SEHHandler Handler : LPad->SEHHandlers) {
380 Asm->OutStreamer->EmitValue(Begin, 4);
381 Asm->OutStreamer->EmitValue(End, 4);
383 // Emit the filter or finally function pointer, if present. Otherwise,
384 // emit '1' to indicate a catch-all.
385 const Function *F = Handler.FilterOrFinally;
387 Asm->OutStreamer->EmitValue(create32bitRef(Asm->getSymbol(F)), 4);
389 Asm->OutStreamer->EmitIntValue(1, 4);
391 // Emit the recovery address, if present. Otherwise, this must be a
393 const BlockAddress *BA = Handler.RecoverBA;
395 Asm->OutStreamer->EmitValue(
396 create32bitRef(Asm->GetBlockAddressSymbol(BA)), 4);
398 Asm->OutStreamer->EmitIntValue(0, 4);
403 void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
404 const Function *F = MF->getFunction();
405 auto &OS = *Asm->OutStreamer;
406 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
408 StringRef FuncLinkageName = GlobalValue::getRealLinkageName(F->getName());
410 SmallVector<std::pair<const MCExpr *, int>, 4> IPToStateTable;
411 MCSymbol *FuncInfoXData = nullptr;
412 if (shouldEmitPersonality) {
413 // If we're 64-bit, emit a pointer to the C++ EH data, and build a map from
414 // IPs to state numbers.
416 Asm->OutContext.getOrCreateSymbol(Twine("$cppxdata$", FuncLinkageName));
417 computeIP2StateTable(MF, FuncInfo, IPToStateTable);
419 FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(FuncLinkageName);
420 emitEHRegistrationOffsetLabel(FuncInfo, FuncLinkageName);
423 MCSymbol *UnwindMapXData = nullptr;
424 MCSymbol *TryBlockMapXData = nullptr;
425 MCSymbol *IPToStateXData = nullptr;
426 if (!FuncInfo.UnwindMap.empty())
427 UnwindMapXData = Asm->OutContext.getOrCreateSymbol(
428 Twine("$stateUnwindMap$", FuncLinkageName));
429 if (!FuncInfo.TryBlockMap.empty())
431 Asm->OutContext.getOrCreateSymbol(Twine("$tryMap$", FuncLinkageName));
432 if (!IPToStateTable.empty())
434 Asm->OutContext.getOrCreateSymbol(Twine("$ip2state$", FuncLinkageName));
437 // uint32_t MagicNumber
439 // UnwindMapEntry *UnwindMap;
440 // uint32_t NumTryBlocks;
441 // TryBlockMapEntry *TryBlockMap;
442 // uint32_t IPMapEntries; // always 0 for x86
443 // IPToStateMapEntry *IPToStateMap; // always 0 for x86
444 // uint32_t UnwindHelp; // non-x86 only
445 // ESTypeList *ESTypeList;
448 // EHFlags & 1 -> Synchronous exceptions only, no async exceptions.
449 // EHFlags & 2 -> ???
450 // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue.
451 OS.EmitValueToAlignment(4);
452 OS.EmitLabel(FuncInfoXData);
453 OS.EmitIntValue(0x19930522, 4); // MagicNumber
454 OS.EmitIntValue(FuncInfo.UnwindMap.size(), 4); // MaxState
455 OS.EmitValue(create32bitRef(UnwindMapXData), 4); // UnwindMap
456 OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4); // NumTryBlocks
457 OS.EmitValue(create32bitRef(TryBlockMapXData), 4); // TryBlockMap
458 OS.EmitIntValue(IPToStateTable.size(), 4); // IPMapEntries
459 OS.EmitValue(create32bitRef(IPToStateXData), 4); // IPToStateMap
460 if (Asm->MAI->usesWindowsCFI())
461 OS.EmitIntValue(FuncInfo.UnwindHelpFrameOffset, 4); // UnwindHelp
462 OS.EmitIntValue(0, 4); // ESTypeList
463 OS.EmitIntValue(1, 4); // EHFlags
469 if (UnwindMapXData) {
470 OS.EmitLabel(UnwindMapXData);
471 for (const WinEHUnwindMapEntry &UME : FuncInfo.UnwindMap) {
472 MCSymbol *CleanupSym = getMCSymbolForMBBOrGV(Asm, UME.Cleanup);
473 OS.EmitIntValue(UME.ToState, 4); // ToState
474 OS.EmitValue(create32bitRef(CleanupSym), 4); // Action
481 // int32_t CatchHigh;
482 // int32_t NumCatches;
483 // HandlerType *HandlerArray;
485 if (TryBlockMapXData) {
486 OS.EmitLabel(TryBlockMapXData);
487 SmallVector<MCSymbol *, 1> HandlerMaps;
488 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
489 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
491 MCSymbol *HandlerMapXData = nullptr;
492 if (!TBME.HandlerArray.empty())
494 Asm->OutContext.getOrCreateSymbol(Twine("$handlerMap$")
497 .concat(FuncLinkageName));
498 HandlerMaps.push_back(HandlerMapXData);
500 // TBMEs should form intervals.
501 assert(0 <= TBME.TryLow && "bad trymap interval");
502 assert(TBME.TryLow <= TBME.TryHigh && "bad trymap interval");
503 assert(TBME.TryHigh < TBME.CatchHigh && "bad trymap interval");
504 assert(TBME.CatchHigh < int(FuncInfo.UnwindMap.size()) &&
505 "bad trymap interval");
507 OS.EmitIntValue(TBME.TryLow, 4); // TryLow
508 OS.EmitIntValue(TBME.TryHigh, 4); // TryHigh
509 OS.EmitIntValue(TBME.CatchHigh, 4); // CatchHigh
510 OS.EmitIntValue(TBME.HandlerArray.size(), 4); // NumCatches
511 OS.EmitValue(create32bitRef(HandlerMapXData), 4); // HandlerArray
514 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
515 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
516 MCSymbol *HandlerMapXData = HandlerMaps[I];
517 if (!HandlerMapXData)
520 // int32_t Adjectives;
521 // TypeDescriptor *Type;
522 // int32_t CatchObjOffset;
523 // void (*Handler)();
524 // int32_t ParentFrameOffset; // x64 only
526 OS.EmitLabel(HandlerMapXData);
527 for (const WinEHHandlerType &HT : TBME.HandlerArray) {
528 // Get the frame escape label with the offset of the catch object. If
529 // the index is -1, then there is no catch object, and we should emit an
530 // offset of zero, indicating that no copy will occur.
531 const MCExpr *FrameAllocOffsetRef = nullptr;
532 if (HT.CatchObjRecoverIdx >= 0) {
533 MCSymbol *FrameAllocOffset =
534 Asm->OutContext.getOrCreateFrameAllocSymbol(
535 FuncLinkageName, HT.CatchObjRecoverIdx);
536 FrameAllocOffsetRef = MCSymbolRefExpr::create(
537 FrameAllocOffset, MCSymbolRefExpr::VK_None, Asm->OutContext);
538 } else if (HT.CatchObj.FrameOffset != INT_MAX) {
539 int Offset = HT.CatchObj.FrameOffset;
540 // For 32-bit, the catch object offset is relative to the end of the
541 // EH registration node. For 64-bit, it's relative to SP at the end of
543 if (!shouldEmitPersonality) {
544 assert(FuncInfo.EHRegNodeEndOffset != INT_MAX);
545 Offset += FuncInfo.EHRegNodeEndOffset;
547 FrameAllocOffsetRef = MCConstantExpr::create(Offset, Asm->OutContext);
549 FrameAllocOffsetRef = MCConstantExpr::create(0, Asm->OutContext);
552 MCSymbol *HandlerSym = getMCSymbolForMBBOrGV(Asm, HT.Handler);
554 OS.EmitIntValue(HT.Adjectives, 4); // Adjectives
555 OS.EmitValue(create32bitRef(HT.TypeDescriptor), 4); // Type
556 OS.EmitValue(FrameAllocOffsetRef, 4); // CatchObjOffset
557 OS.EmitValue(create32bitRef(HandlerSym), 4); // Handler
559 if (shouldEmitPersonality) {
560 // With the new IR, this is always 16 + 8 + getMaxCallFrameSize().
561 // Keep this in sync with X86FrameLowering::emitPrologue.
562 int ParentFrameOffset =
563 16 + 8 + MF->getFrameInfo()->getMaxCallFrameSize();
564 OS.EmitIntValue(ParentFrameOffset, 4); // ParentFrameOffset
570 // IPToStateMapEntry {
574 if (IPToStateXData) {
575 OS.EmitLabel(IPToStateXData);
576 for (auto &IPStatePair : IPToStateTable) {
577 OS.EmitValue(IPStatePair.first, 4); // IP
578 OS.EmitIntValue(IPStatePair.second, 4); // State
583 void WinException::computeIP2StateTable(
584 const MachineFunction *MF, WinEHFuncInfo &FuncInfo,
585 SmallVectorImpl<std::pair<const MCExpr *, int>> &IPToStateTable) {
586 // Whether there is a potentially throwing instruction (currently this means
587 // an ordinary call) between the end of the previous try-range and now.
588 bool SawPotentiallyThrowing = true;
590 // Remember what state we were in the last time we found a begin try label.
591 // This allows us to coalesce many nearby invokes with the same state into one
593 int LastEHState = -1;
594 MCSymbol *LastEndLabel = Asm->getFunctionBegin();
595 assert(LastEndLabel && "need local function start label");
597 // Indicate that all calls from the prologue to the first invoke unwind to
598 // caller. We handle this as a special case since other ranges starting at end
599 // labels need to use LtmpN+1.
600 IPToStateTable.push_back(std::make_pair(create32bitRef(LastEndLabel), -1));
602 for (const auto &MBB : *MF) {
603 // FIXME: Do we need to emit entries for funclet base states?
605 for (const auto &MI : MBB) {
606 // Find all the EH_LABEL instructions, tracking if we've crossed a
607 // potentially throwing call since the last label.
608 if (!MI.isEHLabel()) {
610 SawPotentiallyThrowing |= !callToNoUnwindFunction(&MI);
614 // If this was an end label, return SawPotentiallyThrowing to the start
615 // state and keep going. Otherwise, we will consider the call between the
616 // begin/end labels to be a potentially throwing call and generate extra
618 MCSymbol *Label = MI.getOperand(0).getMCSymbol();
619 if (Label == LastEndLabel)
620 SawPotentiallyThrowing = false;
622 // Check if this was a begin label. Otherwise, it must be an end label or
623 // some random label, and we should continue.
624 auto StateAndEnd = FuncInfo.InvokeToStateMap.find(Label);
625 if (StateAndEnd == FuncInfo.InvokeToStateMap.end())
628 // Extract the state and end label.
631 std::tie(State, EndLabel) = StateAndEnd->second;
633 // If there was a potentially throwing call between this begin label and
634 // the last end label, we need an extra base state entry to indicate that
635 // those calls unwind directly to the caller.
636 if (SawPotentiallyThrowing && LastEHState != -1) {
637 IPToStateTable.push_back(
638 std::make_pair(getLabelPlusOne(LastEndLabel), -1));
639 SawPotentiallyThrowing = false;
643 // Emit an entry indicating that PCs after 'Label' have this EH state.
644 if (State != LastEHState)
645 IPToStateTable.push_back(std::make_pair(create32bitRef(Label), State));
647 LastEndLabel = EndLabel;
651 if (LastEndLabel != Asm->getFunctionBegin()) {
652 // Indicate that all calls from the last invoke until the epilogue unwind to
653 // caller. This also ensures that we have at least one ip2state entry, if
654 // somehow all invokes were deleted during CodeGen.
655 IPToStateTable.push_back(std::make_pair(getLabelPlusOne(LastEndLabel), -1));
659 void WinException::emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo,
660 StringRef FLinkageName) {
661 // Outlined helpers called by the EH runtime need to know the offset of the EH
662 // registration in order to recover the parent frame pointer. Now that we know
663 // we've code generated the parent, we can emit the label assignment that
664 // those helpers use to get the offset of the registration node.
665 assert(FuncInfo.EHRegNodeEscapeIndex != INT_MAX &&
666 "no EH reg node localescape index");
667 MCSymbol *ParentFrameOffset =
668 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(FLinkageName);
669 MCSymbol *RegistrationOffsetSym = Asm->OutContext.getOrCreateFrameAllocSymbol(
670 FLinkageName, FuncInfo.EHRegNodeEscapeIndex);
671 const MCExpr *RegistrationOffsetSymRef =
672 MCSymbolRefExpr::create(RegistrationOffsetSym, Asm->OutContext);
673 Asm->OutStreamer->EmitAssignment(ParentFrameOffset, RegistrationOffsetSymRef);
676 /// Emit the language-specific data that _except_handler3 and 4 expect. This is
677 /// functionally equivalent to the __C_specific_handler table, except it is
678 /// indexed by state number instead of IP.
679 void WinException::emitExceptHandlerTable(const MachineFunction *MF) {
680 MCStreamer &OS = *Asm->OutStreamer;
681 const Function *F = MF->getFunction();
682 StringRef FLinkageName = GlobalValue::getRealLinkageName(F->getName());
684 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
685 emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
687 // Emit the __ehtable label that we use for llvm.x86.seh.lsda.
688 MCSymbol *LSDALabel = Asm->OutContext.getOrCreateLSDASymbol(FLinkageName);
689 OS.EmitValueToAlignment(4);
690 OS.EmitLabel(LSDALabel);
692 const Function *Per =
693 dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
694 StringRef PerName = Per->getName();
696 if (PerName == "_except_handler4") {
697 // The LSDA for _except_handler4 starts with this struct, followed by the
700 // struct EH4ScopeTable {
701 // int32_t GSCookieOffset;
702 // int32_t GSCookieXOROffset;
703 // int32_t EHCookieOffset;
704 // int32_t EHCookieXOROffset;
705 // ScopeTableEntry ScopeRecord[];
708 // Only the EHCookieOffset field appears to vary, and it appears to be the
709 // offset from the final saved SP value to the retaddr.
710 OS.EmitIntValue(-2, 4);
711 OS.EmitIntValue(0, 4);
713 OS.EmitIntValue(9999, 4);
714 OS.EmitIntValue(0, 4);
718 if (!FuncInfo.SEHUnwindMap.empty()) {
719 for (SEHUnwindMapEntry &UME : FuncInfo.SEHUnwindMap) {
720 MCSymbol *ExceptOrFinally =
721 UME.Handler.get<MachineBasicBlock *>()->getSymbol();
722 OS.EmitIntValue(UME.ToState, 4); // ToState
723 OS.EmitValue(create32bitRef(UME.Filter), 4); // Filter
724 OS.EmitValue(create32bitRef(ExceptOrFinally), 4); // Except/Finally
728 // FIXME: The following code is for the old landingpad-based SEH
729 // implementation. Remove it when possible.
731 // Build a list of pointers to LandingPadInfos and then sort by WinEHState.
732 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
733 SmallVector<const LandingPadInfo *, 4> LPads;
734 LPads.reserve((PadInfos.size()));
735 for (const LandingPadInfo &LPInfo : PadInfos)
736 LPads.push_back(&LPInfo);
737 std::sort(LPads.begin(), LPads.end(),
738 [](const LandingPadInfo *L, const LandingPadInfo *R) {
739 return L->WinEHState < R->WinEHState;
742 // For each action in each lpad, emit one of these:
743 // struct ScopeTableEntry {
744 // int32_t EnclosingLevel;
745 // int32_t (__cdecl *Filter)();
746 // void *HandlerOrFinally;
749 // The "outermost" action will use BaseState as its enclosing level. Each
750 // other action will refer to the previous state as its enclosing level.
752 for (const LandingPadInfo *LPInfo : LPads) {
753 int EnclosingLevel = BaseState;
754 assert(CurState + int(LPInfo->SEHHandlers.size()) - 1 ==
755 LPInfo->WinEHState &&
756 "gaps in the SEH scope table");
757 for (auto I = LPInfo->SEHHandlers.rbegin(), E = LPInfo->SEHHandlers.rend();
759 const SEHHandler &Handler = *I;
760 const BlockAddress *BA = Handler.RecoverBA;
761 const Function *F = Handler.FilterOrFinally;
762 assert(F && "cannot catch all in 32-bit SEH without filter function");
763 const MCExpr *FilterOrNull =
764 create32bitRef(BA ? Asm->getSymbol(F) : nullptr);
765 const MCExpr *ExceptOrFinally = create32bitRef(
766 BA ? Asm->GetBlockAddressSymbol(BA) : Asm->getSymbol(F));
768 OS.EmitIntValue(EnclosingLevel, 4);
769 OS.EmitValue(FilterOrNull, 4);
770 OS.EmitValue(ExceptOrFinally, 4);
772 // The next state unwinds to this state.
773 EnclosingLevel = CurState;