1 //===-- CodeGen/AsmPrinter/Win64Exception.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 "Win64Exception.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/Support/Dwarf.h"
33 #include "llvm/Support/ErrorHandling.h"
34 #include "llvm/Support/FormattedStream.h"
35 #include "llvm/Target/TargetFrameLowering.h"
36 #include "llvm/Target/TargetLoweringObjectFile.h"
37 #include "llvm/Target/TargetOptions.h"
38 #include "llvm/Target/TargetRegisterInfo.h"
41 Win64Exception::Win64Exception(AsmPrinter *A)
42 : EHStreamer(A), shouldEmitPersonality(false), shouldEmitLSDA(false),
43 shouldEmitMoves(false) {}
45 Win64Exception::~Win64Exception() {}
47 /// endModule - Emit all exception information that should come after the
49 void Win64Exception::endModule() {
52 void Win64Exception::beginFunction(const MachineFunction *MF) {
53 shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
55 // If any landing pads survive, we need an EH table.
56 bool hasLandingPads = !MMI->getLandingPads().empty();
58 shouldEmitMoves = Asm->needsSEHMoves();
60 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
61 unsigned PerEncoding = TLOF.getPersonalityEncoding();
62 const Function *Per = MF->getMMI().getPersonality();
64 shouldEmitPersonality = hasLandingPads &&
65 PerEncoding != dwarf::DW_EH_PE_omit && Per;
67 unsigned LSDAEncoding = TLOF.getLSDAEncoding();
68 shouldEmitLSDA = shouldEmitPersonality &&
69 LSDAEncoding != dwarf::DW_EH_PE_omit;
72 // If this was an outlined handler, we need to define the label corresponding
73 // to the offset of the parent frame relative to the stack pointer after the
75 const Function *F = MF->getFunction();
76 const Function *ParentF = MMI->getWinEHParent(F);
78 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(ParentF);
79 auto I = FuncInfo.CatchHandlerParentFrameObjOffset.find(F);
80 if (I != FuncInfo.CatchHandlerParentFrameObjOffset.end()) {
81 MCSymbol *HandlerTypeParentFrameOffset =
82 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(
83 GlobalValue::getRealLinkageName(F->getName()));
85 // Emit a symbol assignment.
86 Asm->OutStreamer.EmitAssignment(
87 HandlerTypeParentFrameOffset,
88 MCConstantExpr::Create(I->second, Asm->OutContext));
92 if (!shouldEmitPersonality && !shouldEmitMoves)
95 Asm->OutStreamer.EmitWinCFIStartProc(Asm->CurrentFnSym);
97 if (!shouldEmitPersonality)
100 const MCSymbol *PersHandlerSym =
101 TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
102 Asm->OutStreamer.EmitWinEHHandler(PersHandlerSym, true, true);
105 /// endFunction - Gather and emit post-function exception information.
107 void Win64Exception::endFunction(const MachineFunction *MF) {
108 if (!shouldEmitPersonality && !shouldEmitMoves)
111 // Map all labels and get rid of any dead landing pads.
112 MMI->TidyLandingPads();
114 if (shouldEmitPersonality) {
115 Asm->OutStreamer.PushSection();
117 // Emit an UNWIND_INFO struct describing the prologue.
118 Asm->OutStreamer.EmitWinEHHandlerData();
120 // Emit the tables appropriate to the personality function in use. If we
121 // don't recognize the personality, assume it uses an Itanium-style LSDA.
122 EHPersonality Per = MMI->getPersonalityType();
123 if (Per == EHPersonality::MSVC_Win64SEH)
124 emitCSpecificHandlerTable();
125 else if (Per == EHPersonality::MSVC_CXX)
126 emitCXXFrameHandler3Table(MF);
128 emitExceptionTable();
130 Asm->OutStreamer.PopSection();
132 Asm->OutStreamer.EmitWinCFIEndProc();
135 const MCExpr *Win64Exception::createImageRel32(const MCSymbol *Value) {
137 return MCConstantExpr::Create(0, Asm->OutContext);
138 return MCSymbolRefExpr::Create(Value, MCSymbolRefExpr::VK_COFF_IMGREL32,
142 const MCExpr *Win64Exception::createImageRel32(const GlobalValue *GV) {
144 return MCConstantExpr::Create(0, Asm->OutContext);
145 return createImageRel32(Asm->getSymbol(GV));
148 /// Emit the language-specific data that __C_specific_handler expects. This
149 /// handler lives in the x64 Microsoft C runtime and allows catching or cleaning
150 /// up after faults with __try, __except, and __finally. The typeinfo values
151 /// are not really RTTI data, but pointers to filter functions that return an
152 /// integer (1, 0, or -1) indicating how to handle the exception. For __finally
153 /// blocks and other cleanups, the landing pad label is zero, and the filter
154 /// function is actually a cleanup handler with the same prototype. A catch-all
155 /// entry is modeled with a null filter function field and a non-zero landing
158 /// Possible filter function return values:
159 /// EXCEPTION_EXECUTE_HANDLER (1):
160 /// Jump to the landing pad label after cleanups.
161 /// EXCEPTION_CONTINUE_SEARCH (0):
162 /// Continue searching this table or continue unwinding.
163 /// EXCEPTION_CONTINUE_EXECUTION (-1):
164 /// Resume execution at the trapping PC.
166 /// Inferred table structure:
170 /// imagerel32 LabelStart;
171 /// imagerel32 LabelEnd;
172 /// imagerel32 FilterOrFinally; // One means catch-all.
173 /// imagerel32 LabelLPad; // Zero means __finally.
174 /// } Entries[NumEntries];
176 void Win64Exception::emitCSpecificHandlerTable() {
177 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
179 // Simplifying assumptions for first implementation:
180 // - Cleanups are not implemented.
181 // - Filters are not implemented.
183 // The Itanium LSDA table sorts similar landing pads together to simplify the
184 // actions table, but we don't need that.
185 SmallVector<const LandingPadInfo *, 64> LandingPads;
186 LandingPads.reserve(PadInfos.size());
187 for (const auto &LP : PadInfos)
188 LandingPads.push_back(&LP);
190 // Compute label ranges for call sites as we would for the Itanium LSDA, but
191 // use an all zero action table because we aren't using these actions.
192 SmallVector<unsigned, 64> FirstActions;
193 FirstActions.resize(LandingPads.size());
194 SmallVector<CallSiteEntry, 64> CallSites;
195 computeCallSiteTable(CallSites, LandingPads, FirstActions);
197 MCSymbol *EHFuncBeginSym = Asm->getFunctionBegin();
198 MCSymbol *EHFuncEndSym = Asm->getFunctionEnd();
200 // Emit the number of table entries.
201 unsigned NumEntries = 0;
202 for (const CallSiteEntry &CSE : CallSites) {
204 continue; // Ignore gaps.
205 for (int Selector : CSE.LPad->TypeIds) {
206 // Ignore C++ filter clauses in SEH.
207 // FIXME: Implement cleanup clauses.
208 if (isCatchEHSelector(Selector))
212 Asm->OutStreamer.EmitIntValue(NumEntries, 4);
214 // Emit the four-label records for each call site entry. The table has to be
215 // sorted in layout order, and the call sites should already be sorted.
216 for (const CallSiteEntry &CSE : CallSites) {
217 // Ignore gaps. Unlike the Itanium model, unwinding through a frame without
218 // an EH table entry will propagate the exception rather than terminating
222 const LandingPadInfo *LPad = CSE.LPad;
224 // Compute the label range. We may reuse the function begin and end labels
225 // rather than forming new ones.
226 const MCExpr *Begin =
227 createImageRel32(CSE.BeginLabel ? CSE.BeginLabel : EHFuncBeginSym);
230 // The interval is half-open, so we have to add one to include the return
231 // address of the last invoke in the range.
232 End = MCBinaryExpr::CreateAdd(createImageRel32(CSE.EndLabel),
233 MCConstantExpr::Create(1, Asm->OutContext),
236 End = createImageRel32(EHFuncEndSym);
239 // These aren't really type info globals, they are actually pointers to
240 // filter functions ordered by selector. The zero selector is used for
241 // cleanups, so slot zero corresponds to selector 1.
242 const std::vector<const GlobalValue *> &SelectorToFilter = MMI->getTypeInfos();
244 // Do a parallel iteration across typeids and clause labels, skipping filter
246 size_t NextClauseLabel = 0;
247 for (size_t I = 0, E = LPad->TypeIds.size(); I < E; ++I) {
248 // AddLandingPadInfo stores the clauses in reverse, but there is a FIXME
250 int Selector = LPad->TypeIds[E - I - 1];
252 // Ignore C++ filter clauses in SEH.
253 // FIXME: Implement cleanup clauses.
254 if (!isCatchEHSelector(Selector))
257 Asm->OutStreamer.EmitValue(Begin, 4);
258 Asm->OutStreamer.EmitValue(End, 4);
259 if (isCatchEHSelector(Selector)) {
260 assert(unsigned(Selector - 1) < SelectorToFilter.size());
261 const GlobalValue *TI = SelectorToFilter[Selector - 1];
262 if (TI) // Emit the filter function pointer.
263 Asm->OutStreamer.EmitValue(createImageRel32(Asm->getSymbol(TI)), 4);
264 else // Otherwise, this is a "catch i8* null", or catch all.
265 Asm->OutStreamer.EmitIntValue(1, 4);
267 MCSymbol *ClauseLabel = LPad->ClauseLabels[NextClauseLabel++];
268 Asm->OutStreamer.EmitValue(createImageRel32(ClauseLabel), 4);
273 void Win64Exception::emitCXXFrameHandler3Table(const MachineFunction *MF) {
274 const Function *F = MF->getFunction();
275 const Function *ParentF = MMI->getWinEHParent(F);
276 auto &OS = Asm->OutStreamer;
277 WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(ParentF);
279 StringRef ParentLinkageName =
280 GlobalValue::getRealLinkageName(ParentF->getName());
282 MCSymbol *FuncInfoXData =
283 Asm->OutContext.GetOrCreateSymbol(Twine("$cppxdata$", ParentLinkageName));
284 OS.EmitValue(createImageRel32(FuncInfoXData), 4);
286 // The Itanium LSDA table sorts similar landing pads together to simplify the
287 // actions table, but we don't need that.
288 SmallVector<const LandingPadInfo *, 64> LandingPads;
289 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
290 LandingPads.reserve(PadInfos.size());
291 for (const auto &LP : PadInfos)
292 LandingPads.push_back(&LP);
295 computePadMap(LandingPads, PadMap);
297 // The end label of the previous invoke or nounwind try-range.
298 MCSymbol *LastLabel = Asm->getFunctionBegin();
300 // Whether there is a potentially throwing instruction (currently this means
301 // an ordinary call) between the end of the previous try-range and now.
302 bool SawPotentiallyThrowing = false;
304 int LastEHState = -2;
306 // The parent function and the catch handlers contribute to the 'ip2state'
308 for (const auto &MBB : *MF) {
309 for (const auto &MI : MBB) {
310 if (!MI.isEHLabel()) {
312 SawPotentiallyThrowing |= !callToNoUnwindFunction(&MI);
316 // End of the previous try-range?
317 MCSymbol *BeginLabel = MI.getOperand(0).getMCSymbol();
318 if (BeginLabel == LastLabel)
319 SawPotentiallyThrowing = false;
321 // Beginning of a new try-range?
322 RangeMapType::const_iterator L = PadMap.find(BeginLabel);
323 if (L == PadMap.end())
324 // Nope, it was just some random label.
327 const PadRange &P = L->second;
328 const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
329 assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
330 "Inconsistent landing pad map!");
332 if (SawPotentiallyThrowing) {
333 FuncInfo.IPToStateList.push_back(std::make_pair(LastLabel, -1));
334 SawPotentiallyThrowing = false;
338 if (LandingPad->WinEHState != LastEHState)
339 FuncInfo.IPToStateList.push_back(
340 std::make_pair(BeginLabel, LandingPad->WinEHState));
341 LastEHState = LandingPad->WinEHState;
342 LastLabel = LandingPad->EndLabels[P.RangeIndex];
346 // Defer emission until we've visited the parent function and all the catch
347 // handlers. Cleanups don't contribute to the ip2state table yet, so don't
349 if (ParentF != F && !FuncInfo.CatchHandlerMaxState.count(F))
351 ++FuncInfo.NumIPToStateFuncsVisited;
352 if (FuncInfo.NumIPToStateFuncsVisited != FuncInfo.CatchHandlerMaxState.size())
355 MCSymbol *UnwindMapXData = nullptr;
356 MCSymbol *TryBlockMapXData = nullptr;
357 MCSymbol *IPToStateXData = nullptr;
358 if (!FuncInfo.UnwindMap.empty())
359 UnwindMapXData = Asm->OutContext.GetOrCreateSymbol(
360 Twine("$stateUnwindMap$", ParentLinkageName));
361 if (!FuncInfo.TryBlockMap.empty())
362 TryBlockMapXData = Asm->OutContext.GetOrCreateSymbol(
363 Twine("$tryMap$", ParentLinkageName));
364 if (!FuncInfo.IPToStateList.empty())
365 IPToStateXData = Asm->OutContext.GetOrCreateSymbol(
366 Twine("$ip2state$", ParentLinkageName));
369 // uint32_t MagicNumber
371 // UnwindMapEntry *UnwindMap;
372 // uint32_t NumTryBlocks;
373 // TryBlockMapEntry *TryBlockMap;
374 // uint32_t IPMapEntries;
375 // IPToStateMapEntry *IPToStateMap;
376 // uint32_t UnwindHelp; // (x64/ARM only)
377 // ESTypeList *ESTypeList;
380 // EHFlags & 1 -> Synchronous exceptions only, no async exceptions.
381 // EHFlags & 2 -> ???
382 // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue.
383 OS.EmitLabel(FuncInfoXData);
384 OS.EmitIntValue(0x19930522, 4); // MagicNumber
385 OS.EmitIntValue(FuncInfo.UnwindMap.size(), 4); // MaxState
386 OS.EmitValue(createImageRel32(UnwindMapXData), 4); // UnwindMap
387 OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4); // NumTryBlocks
388 OS.EmitValue(createImageRel32(TryBlockMapXData), 4); // TryBlockMap
389 OS.EmitIntValue(FuncInfo.IPToStateList.size(), 4); // IPMapEntries
390 OS.EmitValue(createImageRel32(IPToStateXData), 4); // IPToStateMap
391 OS.EmitIntValue(FuncInfo.UnwindHelpFrameOffset, 4); // UnwindHelp
392 OS.EmitIntValue(0, 4); // ESTypeList
393 OS.EmitIntValue(1, 4); // EHFlags
399 if (UnwindMapXData) {
400 OS.EmitLabel(UnwindMapXData);
401 for (const WinEHUnwindMapEntry &UME : FuncInfo.UnwindMap) {
402 OS.EmitIntValue(UME.ToState, 4); // ToState
403 OS.EmitValue(createImageRel32(UME.Cleanup), 4); // Action
410 // int32_t CatchHigh;
411 // int32_t NumCatches;
412 // HandlerType *HandlerArray;
414 if (TryBlockMapXData) {
415 OS.EmitLabel(TryBlockMapXData);
416 SmallVector<MCSymbol *, 1> HandlerMaps;
417 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
418 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
419 MCSymbol *HandlerMapXData = nullptr;
421 if (!TBME.HandlerArray.empty())
423 Asm->OutContext.GetOrCreateSymbol(Twine("$handlerMap$")
426 .concat(ParentLinkageName));
428 HandlerMaps.push_back(HandlerMapXData);
431 for (WinEHHandlerType &HT : TBME.HandlerArray)
433 std::max(CatchHigh, FuncInfo.CatchHandlerMaxState[HT.Handler]);
435 assert(TBME.TryLow <= TBME.TryHigh);
436 assert(CatchHigh > TBME.TryHigh);
437 OS.EmitIntValue(TBME.TryLow, 4); // TryLow
438 OS.EmitIntValue(TBME.TryHigh, 4); // TryHigh
439 OS.EmitIntValue(CatchHigh, 4); // CatchHigh
440 OS.EmitIntValue(TBME.HandlerArray.size(), 4); // NumCatches
441 OS.EmitValue(createImageRel32(HandlerMapXData), 4); // HandlerArray
444 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
445 WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
446 MCSymbol *HandlerMapXData = HandlerMaps[I];
447 if (!HandlerMapXData)
450 // int32_t Adjectives;
451 // TypeDescriptor *Type;
452 // int32_t CatchObjOffset;
453 // void (*Handler)();
454 // int32_t ParentFrameOffset; // x64 only
456 OS.EmitLabel(HandlerMapXData);
457 for (const WinEHHandlerType &HT : TBME.HandlerArray) {
458 MCSymbol *ParentFrameOffset =
459 Asm->OutContext.getOrCreateParentFrameOffsetSymbol(
460 GlobalValue::getRealLinkageName(HT.Handler->getName()));
461 const MCSymbolRefExpr *ParentFrameOffsetRef = MCSymbolRefExpr::Create(
462 ParentFrameOffset, MCSymbolRefExpr::VK_None, Asm->OutContext);
464 // Get the frame escape label with the offset of the catch object. If
465 // the index is -1, then there is no catch object, and we should emit an
466 // offset of zero, indicating that no copy will occur.
467 const MCExpr *FrameAllocOffsetRef = nullptr;
468 if (HT.CatchObjRecoverIdx >= 0) {
469 MCSymbol *FrameAllocOffset =
470 Asm->OutContext.getOrCreateFrameAllocSymbol(
471 GlobalValue::getRealLinkageName(F->getName()),
472 HT.CatchObjRecoverIdx);
473 FrameAllocOffsetRef = MCSymbolRefExpr::Create(
474 FrameAllocOffset, MCSymbolRefExpr::VK_None, Asm->OutContext);
476 FrameAllocOffsetRef = MCConstantExpr::Create(0, Asm->OutContext);
479 OS.EmitIntValue(HT.Adjectives, 4); // Adjectives
480 OS.EmitValue(createImageRel32(HT.TypeDescriptor), 4); // Type
481 OS.EmitValue(FrameAllocOffsetRef, 4); // CatchObjOffset
482 OS.EmitValue(createImageRel32(HT.Handler), 4); // Handler
483 OS.EmitValue(ParentFrameOffsetRef, 4); // ParentFrameOffset
488 // IPToStateMapEntry {
492 if (IPToStateXData) {
493 OS.EmitLabel(IPToStateXData);
494 for (auto &IPStatePair : FuncInfo.IPToStateList) {
495 OS.EmitValue(createImageRel32(IPStatePair.first), 4); // IP
496 OS.EmitIntValue(IPStatePair.second, 4); // State