1//===-- CodeGen/AsmPrinter/WinException.cpp - Dwarf Exception Impl ------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains support for writing Win64 exception info into asm files.
10//
11//===----------------------------------------------------------------------===//
12
13#include "WinException.h"
14#include "llvm/ADT/Twine.h"
15#include "llvm/BinaryFormat/COFF.h"
16#include "llvm/BinaryFormat/Dwarf.h"
17#include "llvm/CodeGen/AsmPrinter.h"
18#include "llvm/CodeGen/MachineFrameInfo.h"
19#include "llvm/CodeGen/MachineFunction.h"
20#include "llvm/CodeGen/MachineModuleInfo.h"
21#include "llvm/CodeGen/TargetFrameLowering.h"
22#include "llvm/CodeGen/TargetLowering.h"
23#include "llvm/CodeGen/TargetSubtargetInfo.h"
24#include "llvm/CodeGen/WinEHFuncInfo.h"
25#include "llvm/IR/DataLayout.h"
26#include "llvm/IR/Module.h"
27#include "llvm/MC/MCAsmInfo.h"
28#include "llvm/MC/MCContext.h"
29#include "llvm/MC/MCExpr.h"
30#include "llvm/MC/MCStreamer.h"
31#include "llvm/Target/TargetLoweringObjectFile.h"
32#include "llvm/Target/TargetMachine.h"
33using namespace llvm;
34
35WinException::WinException(AsmPrinter *A) : EHStreamer(A) {
36 // MSVC's EH tables are always composed of 32-bit words. All known 64-bit
37 // platforms use an imagerel32 relocation to refer to symbols.
38 useImageRel32 = (A->getDataLayout().getPointerSizeInBits() == 64);
39 isAArch64 = Asm->TM.getTargetTriple().isAArch64();
40 isThumb = Asm->TM.getTargetTriple().isThumb();
41}
42
43WinException::~WinException() = default;
44
45/// endModule - Emit all exception information that should come after the
46/// content.
47void WinException::endModule() {
48 auto &OS = *Asm->OutStreamer;
49 const Module *M = MMI->getModule();
50 for (const Function &F : *M)
51 if (F.hasFnAttribute(Kind: "safeseh"))
52 OS.emitCOFFSafeSEH(Symbol: Asm->getSymbol(GV: &F));
53
54 if (M->getModuleFlag(Key: "ehcontguard") && !EHContTargets.empty()) {
55 // Emit the symbol index of each ehcont target.
56 OS.switchSection(Section: Asm->OutContext.getObjectFileInfo()->getGEHContSection());
57 for (const MCSymbol *S : EHContTargets) {
58 OS.emitCOFFSymbolIndex(Symbol: S);
59 }
60 }
61}
62
63void WinException::beginFunction(const MachineFunction *MF) {
64 shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
65
66 // If any landing pads survive, we need an EH table.
67 bool hasLandingPads = !MF->getLandingPads().empty();
68 bool hasEHFunclets = MF->hasEHFunclets();
69
70 const Function &F = MF->getFunction();
71
72 shouldEmitMoves = Asm->needsSEHMoves() && MF->hasWinCFI();
73
74 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
75 unsigned PerEncoding = TLOF.getPersonalityEncoding();
76
77 EHPersonality Per = EHPersonality::Unknown;
78 const Function *PerFn = nullptr;
79 if (F.hasPersonalityFn()) {
80 PerFn = dyn_cast<Function>(Val: F.getPersonalityFn()->stripPointerCasts());
81 Per = classifyEHPersonality(Pers: PerFn);
82 }
83
84 bool forceEmitPersonality = F.hasPersonalityFn() &&
85 !isNoOpWithoutInvoke(Pers: Per) &&
86 F.needsUnwindTableEntry();
87
88 shouldEmitPersonality =
89 forceEmitPersonality || ((hasLandingPads || hasEHFunclets) &&
90 PerEncoding != dwarf::DW_EH_PE_omit && PerFn);
91
92 unsigned LSDAEncoding = TLOF.getLSDAEncoding();
93 shouldEmitLSDA = shouldEmitPersonality &&
94 LSDAEncoding != dwarf::DW_EH_PE_omit;
95
96 // If we're not using CFI, we don't want the CFI or the personality, but we
97 // might want EH tables if we had EH pads.
98 if (!Asm->MAI->usesWindowsCFI()) {
99 if (Per == EHPersonality::MSVC_X86SEH && !hasEHFunclets) {
100 // If this is 32-bit SEH and we don't have any funclets (really invokes),
101 // make sure we emit the parent offset label. Some unreferenced filter
102 // functions may still refer to it.
103 const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
104 StringRef FLinkageName =
105 GlobalValue::dropLLVMManglingEscape(Name: MF->getFunction().getName());
106 emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
107 }
108 shouldEmitLSDA = hasEHFunclets;
109 shouldEmitPersonality = false;
110 return;
111 }
112
113 beginFunclet(MBB: MF->front(), Sym: Asm->CurrentFnSym);
114}
115
116void WinException::markFunctionEnd() {
117 if (isAArch64 && CurrentFuncletEntry &&
118 (shouldEmitMoves || shouldEmitPersonality))
119 Asm->OutStreamer->emitWinCFIFuncletOrFuncEnd();
120}
121
122/// endFunction - Gather and emit post-function exception information.
123///
124void WinException::endFunction(const MachineFunction *MF) {
125 if (!shouldEmitPersonality && !shouldEmitMoves && !shouldEmitLSDA)
126 return;
127
128 const Function &F = MF->getFunction();
129 EHPersonality Per = EHPersonality::Unknown;
130 if (F.hasPersonalityFn())
131 Per = classifyEHPersonality(Pers: F.getPersonalityFn()->stripPointerCasts());
132
133 endFuncletImpl();
134
135 // endFunclet will emit the necessary .xdata tables for table-based SEH.
136 if (Per == EHPersonality::MSVC_TableSEH && MF->hasEHFunclets())
137 return;
138
139 if (shouldEmitPersonality || shouldEmitLSDA) {
140 Asm->OutStreamer->pushSection();
141
142 // Just switch sections to the right xdata section.
143 MCSection *XData = Asm->OutStreamer->getAssociatedXDataSection(
144 TextSec: Asm->OutStreamer->getCurrentSectionOnly());
145 Asm->OutStreamer->switchSection(Section: XData);
146
147 // Emit the tables appropriate to the personality function in use. If we
148 // don't recognize the personality, assume it uses an Itanium-style LSDA.
149 if (Per == EHPersonality::MSVC_TableSEH)
150 emitCSpecificHandlerTable(MF);
151 else if (Per == EHPersonality::MSVC_X86SEH)
152 emitExceptHandlerTable(MF);
153 else if (Per == EHPersonality::MSVC_CXX)
154 emitCXXFrameHandler3Table(MF);
155 else if (Per == EHPersonality::CoreCLR)
156 emitCLRExceptionTable(MF);
157 else
158 emitExceptionTable();
159
160 Asm->OutStreamer->popSection();
161 }
162
163 if (!MF->getEHContTargets().empty()) {
164 // Copy the function's EH Continuation targets to a module-level list.
165 llvm::append_range(C&: EHContTargets, R: MF->getEHContTargets());
166 }
167}
168
169/// Retrieve the MCSymbol for a GlobalValue or MachineBasicBlock.
170static MCSymbol *getMCSymbolForMBB(AsmPrinter *Asm,
171 const MachineBasicBlock *MBB) {
172 if (!MBB)
173 return nullptr;
174
175 assert(MBB->isEHFuncletEntry());
176
177 // Give catches and cleanups a name based off of their parent function and
178 // their funclet entry block's number.
179 const MachineFunction *MF = MBB->getParent();
180 const Function &F = MF->getFunction();
181 StringRef FuncLinkageName = GlobalValue::dropLLVMManglingEscape(Name: F.getName());
182 MCContext &Ctx = MF->getContext();
183 StringRef HandlerPrefix = MBB->isCleanupFuncletEntry() ? "dtor" : "catch";
184 return Ctx.getOrCreateSymbol(Name: "?" + HandlerPrefix + "$" +
185 Twine(MBB->getNumber()) + "@?0?" +
186 FuncLinkageName + "@4HA");
187}
188
189void WinException::beginFunclet(const MachineBasicBlock &MBB,
190 MCSymbol *Sym) {
191 CurrentFuncletEntry = &MBB;
192
193 const Function &F = Asm->MF->getFunction();
194 // If a symbol was not provided for the funclet, invent one.
195 if (!Sym) {
196 Sym = getMCSymbolForMBB(Asm, MBB: &MBB);
197
198 // Describe our funclet symbol as a function with internal linkage.
199 Asm->OutStreamer->beginCOFFSymbolDef(Symbol: Sym);
200 Asm->OutStreamer->emitCOFFSymbolStorageClass(StorageClass: COFF::IMAGE_SYM_CLASS_STATIC);
201 Asm->OutStreamer->emitCOFFSymbolType(Type: COFF::IMAGE_SYM_DTYPE_FUNCTION
202 << COFF::SCT_COMPLEX_TYPE_SHIFT);
203 Asm->OutStreamer->endCOFFSymbolDef();
204
205 // We want our funclet's entry point to be aligned such that no nops will be
206 // present after the label.
207 Asm->emitAlignment(Alignment: std::max(a: Asm->MF->getAlignment(), b: MBB.getAlignment()),
208 GV: &F);
209
210 // Now that we've emitted the alignment directive, point at our funclet.
211 Asm->OutStreamer->emitLabel(Symbol: Sym);
212 }
213
214 // Mark 'Sym' as starting our funclet.
215 if (shouldEmitMoves || shouldEmitPersonality) {
216 CurrentFuncletTextSection = Asm->OutStreamer->getCurrentSectionOnly();
217 Asm->OutStreamer->emitWinCFIStartProc(Symbol: Sym);
218 }
219
220 if (shouldEmitPersonality) {
221 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
222 const Function *PerFn = nullptr;
223
224 // Determine which personality routine we are using for this funclet.
225 if (F.hasPersonalityFn())
226 PerFn = dyn_cast<Function>(Val: F.getPersonalityFn()->stripPointerCasts());
227 const MCSymbol *PersHandlerSym =
228 TLOF.getCFIPersonalitySymbol(GV: PerFn, TM: Asm->TM, MMI);
229
230 // Do not emit a .seh_handler directives for cleanup funclets.
231 // FIXME: This means cleanup funclets cannot handle exceptions. Given that
232 // Clang doesn't produce EH constructs inside cleanup funclets and LLVM's
233 // inliner doesn't allow inlining them, this isn't a major problem in
234 // practice.
235 if (!CurrentFuncletEntry->isCleanupFuncletEntry())
236 Asm->OutStreamer->emitWinEHHandler(Sym: PersHandlerSym, Unwind: true, Except: true);
237 }
238}
239
240void WinException::endFunclet() {
241 if (isAArch64 && CurrentFuncletEntry &&
242 (shouldEmitMoves || shouldEmitPersonality)) {
243 Asm->OutStreamer->switchSection(Section: CurrentFuncletTextSection);
244 Asm->OutStreamer->emitWinCFIFuncletOrFuncEnd();
245 }
246 endFuncletImpl();
247}
248
249void WinException::endFuncletImpl() {
250 // No funclet to process? Great, we have nothing to do.
251 if (!CurrentFuncletEntry)
252 return;
253
254 const MachineFunction *MF = Asm->MF;
255 if (shouldEmitMoves || shouldEmitPersonality) {
256 const Function &F = MF->getFunction();
257 EHPersonality Per = EHPersonality::Unknown;
258 if (F.hasPersonalityFn())
259 Per = classifyEHPersonality(Pers: F.getPersonalityFn()->stripPointerCasts());
260
261 if (Per == EHPersonality::MSVC_CXX && shouldEmitPersonality &&
262 !CurrentFuncletEntry->isCleanupFuncletEntry()) {
263 // Emit an UNWIND_INFO struct describing the prologue.
264 Asm->OutStreamer->emitWinEHHandlerData();
265
266 // If this is a C++ catch funclet (or the parent function),
267 // emit a reference to the LSDA for the parent function.
268 StringRef FuncLinkageName = GlobalValue::dropLLVMManglingEscape(Name: F.getName());
269 MCSymbol *FuncInfoXData = Asm->OutContext.getOrCreateSymbol(
270 Name: Twine("$cppxdata$", FuncLinkageName));
271 Asm->OutStreamer->emitValue(Value: create32bitRef(Value: FuncInfoXData), Size: 4);
272 } else if (Per == EHPersonality::MSVC_TableSEH && MF->hasEHFunclets() &&
273 !CurrentFuncletEntry->isEHFuncletEntry()) {
274 // Emit an UNWIND_INFO struct describing the prologue.
275 Asm->OutStreamer->emitWinEHHandlerData();
276
277 // If this is the parent function in Win64 SEH, emit the LSDA immediately
278 // following .seh_handlerdata.
279 emitCSpecificHandlerTable(MF);
280 } else if (shouldEmitPersonality || shouldEmitLSDA) {
281 // Emit an UNWIND_INFO struct describing the prologue.
282 Asm->OutStreamer->emitWinEHHandlerData();
283 // In these cases, no further info is written to the .xdata section
284 // right here, but is written by e.g. emitExceptionTable in endFunction()
285 // above.
286 } else {
287 // No need to emit the EH handler data right here if nothing needs
288 // writing to the .xdata section; it will be emitted for all
289 // functions that need it in the end anyway.
290 }
291
292 if (!MF->getEHContTargets().empty()) {
293 // Copy the function's EH Continuation targets to a module-level list.
294 llvm::append_range(C&: EHContTargets, R: MF->getEHContTargets());
295 }
296
297 // Switch back to the funclet start .text section now that we are done
298 // writing to .xdata, and emit an .seh_endproc directive to mark the end of
299 // the function.
300 Asm->OutStreamer->switchSection(Section: CurrentFuncletTextSection);
301 Asm->OutStreamer->emitWinCFIEndProc();
302 }
303
304 // Let's make sure we don't try to end the same funclet twice.
305 CurrentFuncletEntry = nullptr;
306}
307
308const MCExpr *WinException::create32bitRef(const MCSymbol *Value) {
309 if (!Value)
310 return MCConstantExpr::create(Value: 0, Ctx&: Asm->OutContext);
311 auto Spec = useImageRel32 ? uint16_t(MCSymbolRefExpr::VK_COFF_IMGREL32) : 0;
312 return MCSymbolRefExpr::create(Symbol: Value, specifier: Spec, Ctx&: Asm->OutContext);
313}
314
315const MCExpr *WinException::create32bitRef(const GlobalValue *GV) {
316 if (!GV)
317 return MCConstantExpr::create(Value: 0, Ctx&: Asm->OutContext);
318 return create32bitRef(Value: Asm->getSymbol(GV));
319}
320
321const MCExpr *WinException::getLabel(const MCSymbol *Label) {
322 return MCSymbolRefExpr::create(Symbol: Label, specifier: MCSymbolRefExpr::VK_COFF_IMGREL32,
323 Ctx&: Asm->OutContext);
324}
325
326const MCExpr *WinException::getLabelPlusOne(const MCSymbol *Label) {
327 return MCBinaryExpr::createAdd(LHS: getLabel(Label),
328 RHS: MCConstantExpr::create(Value: 1, Ctx&: Asm->OutContext),
329 Ctx&: Asm->OutContext);
330}
331
332const MCExpr *WinException::getOffset(const MCSymbol *OffsetOf,
333 const MCSymbol *OffsetFrom) {
334 return MCBinaryExpr::createSub(
335 LHS: MCSymbolRefExpr::create(Symbol: OffsetOf, Ctx&: Asm->OutContext),
336 RHS: MCSymbolRefExpr::create(Symbol: OffsetFrom, Ctx&: Asm->OutContext), Ctx&: Asm->OutContext);
337}
338
339const MCExpr *WinException::getOffsetPlusOne(const MCSymbol *OffsetOf,
340 const MCSymbol *OffsetFrom) {
341 return MCBinaryExpr::createAdd(LHS: getOffset(OffsetOf, OffsetFrom),
342 RHS: MCConstantExpr::create(Value: 1, Ctx&: Asm->OutContext),
343 Ctx&: Asm->OutContext);
344}
345
346int WinException::getFrameIndexOffset(int FrameIndex,
347 const WinEHFuncInfo &FuncInfo) {
348 const TargetFrameLowering &TFI = *Asm->MF->getSubtarget().getFrameLowering();
349 Register UnusedReg;
350 if (Asm->MAI->usesWindowsCFI()) {
351 StackOffset Offset =
352 TFI.getFrameIndexReferencePreferSP(MF: *Asm->MF, FI: FrameIndex, FrameReg&: UnusedReg,
353 /*IgnoreSPUpdates*/ true);
354 assert(UnusedReg ==
355 Asm->MF->getSubtarget()
356 .getTargetLowering()
357 ->getStackPointerRegisterToSaveRestore());
358 return Offset.getFixed();
359 }
360
361 // For 32-bit, offsets should be relative to the end of the EH registration
362 // node. For 64-bit, it's relative to SP at the end of the prologue.
363 assert(FuncInfo.EHRegNodeEndOffset != INT_MAX);
364 StackOffset Offset = TFI.getFrameIndexReference(MF: *Asm->MF, FI: FrameIndex, FrameReg&: UnusedReg);
365 Offset += StackOffset::getFixed(Fixed: FuncInfo.EHRegNodeEndOffset);
366 assert(!Offset.getScalable() &&
367 "Frame offsets with a scalable component are not supported");
368 return Offset.getFixed();
369}
370
371namespace {
372
373/// Top-level state used to represent unwind to caller
374const int NullState = -1;
375
376struct InvokeStateChange {
377 /// EH Label immediately after the last invoke in the previous state, or
378 /// nullptr if the previous state was the null state.
379 const MCSymbol *PreviousEndLabel;
380
381 /// EH label immediately before the first invoke in the new state, or nullptr
382 /// if the new state is the null state.
383 const MCSymbol *NewStartLabel;
384
385 /// State of the invoke following NewStartLabel, or NullState to indicate
386 /// the presence of calls which may unwind to caller.
387 int NewState;
388};
389
390/// Iterator that reports all the invoke state changes in a range of machine
391/// basic blocks. Changes to the null state are reported whenever a call that
392/// may unwind to caller is encountered. The MBB range is expected to be an
393/// entire function or funclet, and the start and end of the range are treated
394/// as being in the NullState even if there's not an unwind-to-caller call
395/// before the first invoke or after the last one (i.e., the first state change
396/// reported is the first change to something other than NullState, and a
397/// change back to NullState is always reported at the end of iteration).
398class InvokeStateChangeIterator {
399 InvokeStateChangeIterator(const WinEHFuncInfo &EHInfo,
400 MachineFunction::const_iterator MFI,
401 MachineFunction::const_iterator MFE,
402 MachineBasicBlock::const_iterator MBBI,
403 int BaseState)
404 : EHInfo(EHInfo), MFI(MFI), MFE(MFE), MBBI(MBBI), BaseState(BaseState) {
405 LastStateChange.PreviousEndLabel = nullptr;
406 LastStateChange.NewStartLabel = nullptr;
407 LastStateChange.NewState = BaseState;
408 scan();
409 }
410
411public:
412 static iterator_range<InvokeStateChangeIterator>
413 range(const WinEHFuncInfo &EHInfo, MachineFunction::const_iterator Begin,
414 MachineFunction::const_iterator End, int BaseState = NullState) {
415 // Reject empty ranges to simplify bookkeeping by ensuring that we can get
416 // the end of the last block.
417 assert(Begin != End);
418 auto BlockBegin = Begin->begin();
419 auto BlockEnd = std::prev(x: End)->end();
420 return make_range(
421 x: InvokeStateChangeIterator(EHInfo, Begin, End, BlockBegin, BaseState),
422 y: InvokeStateChangeIterator(EHInfo, End, End, BlockEnd, BaseState));
423 }
424
425 // Iterator methods.
426 bool operator==(const InvokeStateChangeIterator &O) const {
427 assert(BaseState == O.BaseState);
428 // Must be visiting same block.
429 if (MFI != O.MFI)
430 return false;
431 // Must be visiting same isntr.
432 if (MBBI != O.MBBI)
433 return false;
434 // At end of block/instr iteration, we can still have two distinct states:
435 // one to report the final EndLabel, and another indicating the end of the
436 // state change iteration. Check for CurrentEndLabel equality to
437 // distinguish these.
438 return CurrentEndLabel == O.CurrentEndLabel;
439 }
440
441 bool operator!=(const InvokeStateChangeIterator &O) const {
442 return !operator==(O);
443 }
444 InvokeStateChange &operator*() { return LastStateChange; }
445 InvokeStateChange *operator->() { return &LastStateChange; }
446 InvokeStateChangeIterator &operator++() { return scan(); }
447
448private:
449 InvokeStateChangeIterator &scan();
450
451 const WinEHFuncInfo &EHInfo;
452 const MCSymbol *CurrentEndLabel = nullptr;
453 MachineFunction::const_iterator MFI;
454 MachineFunction::const_iterator MFE;
455 MachineBasicBlock::const_iterator MBBI;
456 InvokeStateChange LastStateChange;
457 bool VisitingInvoke = false;
458 int BaseState;
459};
460
461} // end anonymous namespace
462
463InvokeStateChangeIterator &InvokeStateChangeIterator::scan() {
464 bool IsNewBlock = false;
465 for (; MFI != MFE; ++MFI, IsNewBlock = true) {
466 if (IsNewBlock)
467 MBBI = MFI->begin();
468 for (auto MBBE = MFI->end(); MBBI != MBBE; ++MBBI) {
469 const MachineInstr &MI = *MBBI;
470 if (!VisitingInvoke && LastStateChange.NewState != BaseState &&
471 MI.isCall() && !EHStreamer::callToNoUnwindFunction(MI: &MI)) {
472 // Indicate a change of state to the null state. We don't have
473 // start/end EH labels handy but the caller won't expect them for
474 // null state regions.
475 LastStateChange.PreviousEndLabel = CurrentEndLabel;
476 LastStateChange.NewStartLabel = nullptr;
477 LastStateChange.NewState = BaseState;
478 CurrentEndLabel = nullptr;
479 // Don't re-visit this instr on the next scan
480 ++MBBI;
481 return *this;
482 }
483
484 // All other state changes are at EH labels before/after invokes.
485 if (!MI.isEHLabel())
486 continue;
487 MCSymbol *Label = MI.getOperand(i: 0).getMCSymbol();
488 if (Label == CurrentEndLabel) {
489 VisitingInvoke = false;
490 continue;
491 }
492 auto InvokeMapIter = EHInfo.LabelToStateMap.find(Val: Label);
493 // Ignore EH labels that aren't the ones inserted before an invoke
494 if (InvokeMapIter == EHInfo.LabelToStateMap.end())
495 continue;
496 auto &StateAndEnd = InvokeMapIter->second;
497 int NewState = StateAndEnd.first;
498 // Keep track of the fact that we're between EH start/end labels so
499 // we know not to treat the inoke we'll see as unwinding to caller.
500 VisitingInvoke = true;
501 if (NewState == LastStateChange.NewState) {
502 // The state isn't actually changing here. Record the new end and
503 // keep going.
504 CurrentEndLabel = StateAndEnd.second;
505 continue;
506 }
507 // Found a state change to report
508 LastStateChange.PreviousEndLabel = CurrentEndLabel;
509 LastStateChange.NewStartLabel = Label;
510 LastStateChange.NewState = NewState;
511 // Start keeping track of the new current end
512 CurrentEndLabel = StateAndEnd.second;
513 // Don't re-visit this instr on the next scan
514 ++MBBI;
515 return *this;
516 }
517 }
518 // Iteration hit the end of the block range.
519 if (LastStateChange.NewState != BaseState) {
520 // Report the end of the last new state
521 LastStateChange.PreviousEndLabel = CurrentEndLabel;
522 LastStateChange.NewStartLabel = nullptr;
523 LastStateChange.NewState = BaseState;
524 // Leave CurrentEndLabel non-null to distinguish this state from end.
525 assert(CurrentEndLabel != nullptr);
526 return *this;
527 }
528 // We've reported all state changes and hit the end state.
529 CurrentEndLabel = nullptr;
530 return *this;
531}
532
533/// Emit the language-specific data that __C_specific_handler expects. This
534/// handler lives in the x64 Microsoft C runtime and allows catching or cleaning
535/// up after faults with __try, __except, and __finally. The typeinfo values
536/// are not really RTTI data, but pointers to filter functions that return an
537/// integer (1, 0, or -1) indicating how to handle the exception. For __finally
538/// blocks and other cleanups, the landing pad label is zero, and the filter
539/// function is actually a cleanup handler with the same prototype. A catch-all
540/// entry is modeled with a null filter function field and a non-zero landing
541/// pad label.
542///
543/// Possible filter function return values:
544/// EXCEPTION_EXECUTE_HANDLER (1):
545/// Jump to the landing pad label after cleanups.
546/// EXCEPTION_CONTINUE_SEARCH (0):
547/// Continue searching this table or continue unwinding.
548/// EXCEPTION_CONTINUE_EXECUTION (-1):
549/// Resume execution at the trapping PC.
550///
551/// Inferred table structure:
552/// struct Table {
553/// int NumEntries;
554/// struct Entry {
555/// imagerel32 LabelStart; // Inclusive
556/// imagerel32 LabelEnd; // Exclusive
557/// imagerel32 FilterOrFinally; // One means catch-all.
558/// imagerel32 LabelLPad; // Zero means __finally.
559/// } Entries[NumEntries];
560/// };
561void WinException::emitCSpecificHandlerTable(const MachineFunction *MF) {
562 auto &OS = *Asm->OutStreamer;
563 MCContext &Ctx = Asm->OutContext;
564 const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
565
566 bool VerboseAsm = OS.isVerboseAsm();
567 auto AddComment = [&](const Twine &Comment) {
568 if (VerboseAsm)
569 OS.AddComment(T: Comment);
570 };
571
572 if (!isAArch64) {
573 // Emit a label assignment with the SEH frame offset so we can use it for
574 // llvm.eh.recoverfp.
575 StringRef FLinkageName =
576 GlobalValue::dropLLVMManglingEscape(Name: MF->getFunction().getName());
577 MCSymbol *ParentFrameOffset =
578 Ctx.getOrCreateParentFrameOffsetSymbol(FuncName: FLinkageName);
579 const MCExpr *MCOffset =
580 MCConstantExpr::create(Value: FuncInfo.SEHSetFrameOffset, Ctx);
581 Asm->OutStreamer->emitAssignment(Symbol: ParentFrameOffset, Value: MCOffset);
582 }
583
584 // Use the assembler to compute the number of table entries through label
585 // difference and division.
586 MCSymbol *TableBegin =
587 Ctx.createTempSymbol(Name: "lsda_begin", /*AlwaysAddSuffix=*/true);
588 MCSymbol *TableEnd =
589 Ctx.createTempSymbol(Name: "lsda_end", /*AlwaysAddSuffix=*/true);
590 const MCExpr *LabelDiff = getOffset(OffsetOf: TableEnd, OffsetFrom: TableBegin);
591 const MCExpr *EntrySize = MCConstantExpr::create(Value: 16, Ctx);
592 const MCExpr *EntryCount = MCBinaryExpr::createDiv(LHS: LabelDiff, RHS: EntrySize, Ctx);
593 AddComment("Number of call sites");
594 OS.emitValue(Value: EntryCount, Size: 4);
595
596 OS.emitLabel(Symbol: TableBegin);
597
598 // Iterate over all the invoke try ranges. Unlike MSVC, LLVM currently only
599 // models exceptions from invokes. LLVM also allows arbitrary reordering of
600 // the code, so our tables end up looking a bit different. Rather than
601 // trying to match MSVC's tables exactly, we emit a denormalized table. For
602 // each range of invokes in the same state, we emit table entries for all
603 // the actions that would be taken in that state. This means our tables are
604 // slightly bigger, which is OK.
605 const MCSymbol *LastStartLabel = nullptr;
606 int LastEHState = -1;
607 // Break out before we enter into a finally funclet.
608 // FIXME: We need to emit separate EH tables for cleanups.
609 MachineFunction::const_iterator End = MF->end();
610 MachineFunction::const_iterator Stop = std::next(x: MF->begin());
611 while (Stop != End && !Stop->isEHFuncletEntry())
612 ++Stop;
613 for (const auto &StateChange :
614 InvokeStateChangeIterator::range(EHInfo: FuncInfo, Begin: MF->begin(), End: Stop)) {
615 // Emit all the actions for the state we just transitioned out of
616 // if it was not the null state
617 if (LastEHState != -1)
618 emitSEHActionsForRange(FuncInfo, BeginLabel: LastStartLabel,
619 EndLabel: StateChange.PreviousEndLabel, State: LastEHState);
620 LastStartLabel = StateChange.NewStartLabel;
621 LastEHState = StateChange.NewState;
622 }
623
624 OS.emitLabel(Symbol: TableEnd);
625}
626
627void WinException::emitSEHActionsForRange(const WinEHFuncInfo &FuncInfo,
628 const MCSymbol *BeginLabel,
629 const MCSymbol *EndLabel, int State) {
630 auto &OS = *Asm->OutStreamer;
631 MCContext &Ctx = Asm->OutContext;
632 bool VerboseAsm = OS.isVerboseAsm();
633 auto AddComment = [&](const Twine &Comment) {
634 if (VerboseAsm)
635 OS.AddComment(T: Comment);
636 };
637
638 assert(BeginLabel && EndLabel);
639 while (State != -1) {
640 const SEHUnwindMapEntry &UME = FuncInfo.SEHUnwindMap[State];
641 const MCExpr *FilterOrFinally;
642 const MCExpr *ExceptOrNull;
643 auto *Handler = cast<MachineBasicBlock *>(Val: UME.Handler);
644 if (UME.IsFinally) {
645 FilterOrFinally = create32bitRef(Value: getMCSymbolForMBB(Asm, MBB: Handler));
646 ExceptOrNull = MCConstantExpr::create(Value: 0, Ctx);
647 } else {
648 // For an except, the filter can be 1 (catch-all) or a function
649 // label.
650 FilterOrFinally = UME.Filter ? create32bitRef(GV: UME.Filter)
651 : MCConstantExpr::create(Value: 1, Ctx);
652 ExceptOrNull = create32bitRef(Value: Handler->getSymbol());
653 }
654
655 AddComment("LabelStart");
656 OS.emitValue(Value: getLabel(Label: BeginLabel), Size: 4);
657 AddComment("LabelEnd");
658 OS.emitValue(Value: getLabelPlusOne(Label: EndLabel), Size: 4);
659 AddComment(UME.IsFinally ? "FinallyFunclet" : UME.Filter ? "FilterFunction"
660 : "CatchAll");
661 OS.emitValue(Value: FilterOrFinally, Size: 4);
662 AddComment(UME.IsFinally ? "Null" : "ExceptionHandler");
663 OS.emitValue(Value: ExceptOrNull, Size: 4);
664
665 assert(UME.ToState < State && "states should decrease");
666 State = UME.ToState;
667 }
668}
669
670void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
671 const Function &F = MF->getFunction();
672 auto &OS = *Asm->OutStreamer;
673 const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
674
675 StringRef FuncLinkageName = GlobalValue::dropLLVMManglingEscape(Name: F.getName());
676
677 SmallVector<std::pair<const MCExpr *, int>, 4> IPToStateTable;
678 MCSymbol *FuncInfoXData = nullptr;
679 if (shouldEmitPersonality) {
680 // If we're 64-bit, emit a pointer to the C++ EH data, and build a map from
681 // IPs to state numbers.
682 FuncInfoXData =
683 Asm->OutContext.getOrCreateSymbol(Name: Twine("$cppxdata$", FuncLinkageName));
684 computeIP2StateTable(MF, FuncInfo, IPToStateTable);
685 } else {
686 FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(FuncName: FuncLinkageName);
687 }
688
689 int UnwindHelpOffset = 0;
690 // TODO: The check for UnwindHelpFrameIdx against max() below (and the
691 // second check further below) can be removed if MS C++ unwinding is
692 // implemented for ARM, when test/CodeGen/ARM/Windows/wineh-basic.ll
693 // passes without the check.
694 if (Asm->MAI->usesWindowsCFI() &&
695 FuncInfo.UnwindHelpFrameIdx != std::numeric_limits<int>::max())
696 UnwindHelpOffset =
697 getFrameIndexOffset(FrameIndex: FuncInfo.UnwindHelpFrameIdx, FuncInfo);
698
699 MCSymbol *UnwindMapXData = nullptr;
700 MCSymbol *TryBlockMapXData = nullptr;
701 MCSymbol *IPToStateXData = nullptr;
702 if (!FuncInfo.CxxUnwindMap.empty())
703 UnwindMapXData = Asm->OutContext.getOrCreateSymbol(
704 Name: Twine("$stateUnwindMap$", FuncLinkageName));
705 if (!FuncInfo.TryBlockMap.empty())
706 TryBlockMapXData =
707 Asm->OutContext.getOrCreateSymbol(Name: Twine("$tryMap$", FuncLinkageName));
708 if (!IPToStateTable.empty())
709 IPToStateXData =
710 Asm->OutContext.getOrCreateSymbol(Name: Twine("$ip2state$", FuncLinkageName));
711
712 bool VerboseAsm = OS.isVerboseAsm();
713 auto AddComment = [&](const Twine &Comment) {
714 if (VerboseAsm)
715 OS.AddComment(T: Comment);
716 };
717
718 // FuncInfo {
719 // uint32_t MagicNumber
720 // int32_t MaxState;
721 // UnwindMapEntry *UnwindMap;
722 // uint32_t NumTryBlocks;
723 // TryBlockMapEntry *TryBlockMap;
724 // uint32_t IPMapEntries; // always 0 for x86
725 // IPToStateMapEntry *IPToStateMap; // always 0 for x86
726 // uint32_t UnwindHelp; // non-x86 only
727 // ESTypeList *ESTypeList;
728 // int32_t EHFlags;
729 // }
730 // EHFlags & 1 -> Synchronous exceptions only, no async exceptions.
731 // EHFlags & 2 -> ???
732 // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue.
733 OS.emitValueToAlignment(Alignment: Align(4));
734 OS.emitLabel(Symbol: FuncInfoXData);
735
736 AddComment("MagicNumber");
737 OS.emitInt32(Value: 0x19930522);
738
739 AddComment("MaxState");
740 OS.emitInt32(Value: FuncInfo.CxxUnwindMap.size());
741
742 AddComment("UnwindMap");
743 OS.emitValue(Value: create32bitRef(Value: UnwindMapXData), Size: 4);
744
745 AddComment("NumTryBlocks");
746 OS.emitInt32(Value: FuncInfo.TryBlockMap.size());
747
748 AddComment("TryBlockMap");
749 OS.emitValue(Value: create32bitRef(Value: TryBlockMapXData), Size: 4);
750
751 AddComment("IPMapEntries");
752 OS.emitInt32(Value: IPToStateTable.size());
753
754 AddComment("IPToStateXData");
755 OS.emitValue(Value: create32bitRef(Value: IPToStateXData), Size: 4);
756
757 if (Asm->MAI->usesWindowsCFI() &&
758 FuncInfo.UnwindHelpFrameIdx != std::numeric_limits<int>::max()) {
759 AddComment("UnwindHelp");
760 OS.emitInt32(Value: UnwindHelpOffset);
761 }
762
763 AddComment("ESTypeList");
764 OS.emitInt32(Value: 0);
765
766 AddComment("EHFlags");
767 if (MMI->getModule()->getModuleFlag(Key: "eh-asynch")) {
768 OS.emitInt32(Value: 0);
769 } else {
770 OS.emitInt32(Value: 1);
771 }
772
773 // UnwindMapEntry {
774 // int32_t ToState;
775 // void (*Action)();
776 // };
777 if (UnwindMapXData) {
778 OS.emitLabel(Symbol: UnwindMapXData);
779 for (const CxxUnwindMapEntry &UME : FuncInfo.CxxUnwindMap) {
780 MCSymbol *CleanupSym = getMCSymbolForMBB(
781 Asm, MBB: dyn_cast_if_present<MachineBasicBlock *>(Val: UME.Cleanup));
782 AddComment("ToState");
783 OS.emitInt32(Value: UME.ToState);
784
785 AddComment("Action");
786 OS.emitValue(Value: create32bitRef(Value: CleanupSym), Size: 4);
787 }
788 }
789
790 // TryBlockMap {
791 // int32_t TryLow;
792 // int32_t TryHigh;
793 // int32_t CatchHigh;
794 // int32_t NumCatches;
795 // HandlerType *HandlerArray;
796 // };
797 if (TryBlockMapXData) {
798 OS.emitLabel(Symbol: TryBlockMapXData);
799 SmallVector<MCSymbol *, 1> HandlerMaps;
800 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
801 const WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
802
803 MCSymbol *HandlerMapXData = nullptr;
804 if (!TBME.HandlerArray.empty())
805 HandlerMapXData =
806 Asm->OutContext.getOrCreateSymbol(Name: Twine("$handlerMap$")
807 .concat(Suffix: Twine(I))
808 .concat(Suffix: "$")
809 .concat(Suffix: FuncLinkageName));
810 HandlerMaps.push_back(Elt: HandlerMapXData);
811
812 // TBMEs should form intervals.
813 assert(0 <= TBME.TryLow && "bad trymap interval");
814 assert(TBME.TryLow <= TBME.TryHigh && "bad trymap interval");
815 assert(TBME.TryHigh < TBME.CatchHigh && "bad trymap interval");
816 assert(TBME.CatchHigh < int(FuncInfo.CxxUnwindMap.size()) &&
817 "bad trymap interval");
818
819 AddComment("TryLow");
820 OS.emitInt32(Value: TBME.TryLow);
821
822 AddComment("TryHigh");
823 OS.emitInt32(Value: TBME.TryHigh);
824
825 AddComment("CatchHigh");
826 OS.emitInt32(Value: TBME.CatchHigh);
827
828 AddComment("NumCatches");
829 OS.emitInt32(Value: TBME.HandlerArray.size());
830
831 AddComment("HandlerArray");
832 OS.emitValue(Value: create32bitRef(Value: HandlerMapXData), Size: 4);
833 }
834
835 // All funclets use the same parent frame offset currently.
836 unsigned ParentFrameOffset = 0;
837 if (shouldEmitPersonality) {
838 const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
839 ParentFrameOffset = TFI->getWinEHParentFrameOffset(MF: *MF);
840 }
841
842 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
843 const WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
844 MCSymbol *HandlerMapXData = HandlerMaps[I];
845 if (!HandlerMapXData)
846 continue;
847 // HandlerType {
848 // int32_t Adjectives;
849 // TypeDescriptor *Type;
850 // int32_t CatchObjOffset;
851 // void (*Handler)();
852 // int32_t ParentFrameOffset; // x64 and AArch64 only
853 // };
854 OS.emitLabel(Symbol: HandlerMapXData);
855 for (const WinEHHandlerType &HT : TBME.HandlerArray) {
856 // Get the frame escape label with the offset of the catch object. If
857 // the index is INT_MAX, then there is no catch object, and we should
858 // emit an offset of zero, indicating that no copy will occur.
859 const MCExpr *FrameAllocOffsetRef = nullptr;
860 if (HT.CatchObj.FrameIndex != INT_MAX) {
861 int Offset = getFrameIndexOffset(FrameIndex: HT.CatchObj.FrameIndex, FuncInfo);
862 assert(Offset != 0 && "Illegal offset for catch object!");
863 FrameAllocOffsetRef = MCConstantExpr::create(Value: Offset, Ctx&: Asm->OutContext);
864 } else {
865 FrameAllocOffsetRef = MCConstantExpr::create(Value: 0, Ctx&: Asm->OutContext);
866 }
867
868 MCSymbol *HandlerSym = getMCSymbolForMBB(
869 Asm, MBB: dyn_cast_if_present<MachineBasicBlock *>(Val: HT.Handler));
870
871 AddComment("Adjectives");
872 OS.emitInt32(Value: HT.Adjectives);
873
874 AddComment("Type");
875 OS.emitValue(Value: create32bitRef(GV: HT.TypeDescriptor), Size: 4);
876
877 AddComment("CatchObjOffset");
878 OS.emitValue(Value: FrameAllocOffsetRef, Size: 4);
879
880 AddComment("Handler");
881 OS.emitValue(Value: create32bitRef(Value: HandlerSym), Size: 4);
882
883 if (shouldEmitPersonality) {
884 AddComment("ParentFrameOffset");
885 OS.emitInt32(Value: ParentFrameOffset);
886 }
887 }
888 }
889 }
890
891 // IPToStateMapEntry {
892 // void *IP;
893 // int32_t State;
894 // };
895 if (IPToStateXData) {
896 OS.emitLabel(Symbol: IPToStateXData);
897 for (auto &IPStatePair : IPToStateTable) {
898 AddComment("IP");
899 OS.emitValue(Value: IPStatePair.first, Size: 4);
900 AddComment("ToState");
901 OS.emitInt32(Value: IPStatePair.second);
902 }
903 }
904}
905
906void WinException::computeIP2StateTable(
907 const MachineFunction *MF, const WinEHFuncInfo &FuncInfo,
908 SmallVectorImpl<std::pair<const MCExpr *, int>> &IPToStateTable) {
909
910 for (MachineFunction::const_iterator FuncletStart = MF->begin(),
911 FuncletEnd = MF->begin(),
912 End = MF->end();
913 FuncletStart != End; FuncletStart = FuncletEnd) {
914 // Find the end of the funclet
915 while (++FuncletEnd != End) {
916 if (FuncletEnd->isEHFuncletEntry()) {
917 break;
918 }
919 }
920
921 // Don't emit ip2state entries for cleanup funclets. Any interesting
922 // exceptional actions in cleanups must be handled in a separate IR
923 // function.
924 if (FuncletStart->isCleanupFuncletEntry())
925 continue;
926
927 MCSymbol *StartLabel;
928 int BaseState;
929 if (FuncletStart == MF->begin()) {
930 BaseState = NullState;
931 StartLabel = Asm->getFunctionBegin();
932 } else {
933 auto *FuncletPad = cast<FuncletPadInst>(
934 Val: FuncletStart->getBasicBlock()->getFirstNonPHIIt());
935 assert(FuncInfo.FuncletBaseStateMap.count(FuncletPad) != 0);
936 BaseState = FuncInfo.FuncletBaseStateMap.find(Val: FuncletPad)->second;
937 StartLabel = getMCSymbolForMBB(Asm, MBB: &*FuncletStart);
938 }
939 assert(StartLabel && "need local function start label");
940 IPToStateTable.push_back(
941 Elt: std::make_pair(x: create32bitRef(Value: StartLabel), y&: BaseState));
942
943 for (const auto &StateChange : InvokeStateChangeIterator::range(
944 EHInfo: FuncInfo, Begin: FuncletStart, End: FuncletEnd, BaseState)) {
945 // Compute the label to report as the start of this entry; use the EH
946 // start label for the invoke if we have one, otherwise (this is a call
947 // which may unwind to our caller and does not have an EH start label, so)
948 // use the previous end label.
949 const MCSymbol *ChangeLabel = StateChange.NewStartLabel;
950 if (!ChangeLabel)
951 ChangeLabel = StateChange.PreviousEndLabel;
952 // Emit an entry indicating that PCs after 'Label' have this EH state.
953 // NOTE: On ARM architectures, the StateFromIp automatically takes into
954 // account that the return address is after the call instruction (whose EH
955 // state we should be using), but on other platforms we need to +1 to the
956 // label so that we are using the correct EH state.
957 const MCExpr *LabelExpression = (isAArch64 || isThumb)
958 ? getLabel(Label: ChangeLabel)
959 : getLabelPlusOne(Label: ChangeLabel);
960 IPToStateTable.push_back(
961 Elt: std::make_pair(x&: LabelExpression, y: StateChange.NewState));
962 // FIXME: assert that NewState is between CatchLow and CatchHigh.
963 }
964 }
965}
966
967void WinException::emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo,
968 StringRef FLinkageName) {
969 // Outlined helpers called by the EH runtime need to know the offset of the EH
970 // registration in order to recover the parent frame pointer. Now that we know
971 // we've code generated the parent, we can emit the label assignment that
972 // those helpers use to get the offset of the registration node.
973
974 // Compute the parent frame offset. The EHRegNodeFrameIndex will be invalid if
975 // after optimization all the invokes were eliminated. We still need to emit
976 // the parent frame offset label, but it should be garbage and should never be
977 // used.
978 int64_t Offset = 0;
979 int FI = FuncInfo.EHRegNodeFrameIndex;
980 if (FI != INT_MAX) {
981 const TargetFrameLowering *TFI = Asm->MF->getSubtarget().getFrameLowering();
982 Offset = TFI->getNonLocalFrameIndexReference(MF: *Asm->MF, FI).getFixed();
983 }
984
985 MCContext &Ctx = Asm->OutContext;
986 MCSymbol *ParentFrameOffset =
987 Ctx.getOrCreateParentFrameOffsetSymbol(FuncName: FLinkageName);
988 Asm->OutStreamer->emitAssignment(Symbol: ParentFrameOffset,
989 Value: MCConstantExpr::create(Value: Offset, Ctx));
990}
991
992/// Emit the language-specific data that _except_handler3 and 4 expect. This is
993/// functionally equivalent to the __C_specific_handler table, except it is
994/// indexed by state number instead of IP.
995void WinException::emitExceptHandlerTable(const MachineFunction *MF) {
996 MCStreamer &OS = *Asm->OutStreamer;
997 const Function &F = MF->getFunction();
998 StringRef FLinkageName = GlobalValue::dropLLVMManglingEscape(Name: F.getName());
999
1000 bool VerboseAsm = OS.isVerboseAsm();
1001 auto AddComment = [&](const Twine &Comment) {
1002 if (VerboseAsm)
1003 OS.AddComment(T: Comment);
1004 };
1005
1006 const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
1007 emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
1008
1009 // Emit the __ehtable label that we use for llvm.x86.seh.lsda.
1010 MCSymbol *LSDALabel = Asm->OutContext.getOrCreateLSDASymbol(FuncName: FLinkageName);
1011 OS.emitValueToAlignment(Alignment: Align(4));
1012 OS.emitLabel(Symbol: LSDALabel);
1013
1014 const auto *Per = cast<Function>(Val: F.getPersonalityFn()->stripPointerCasts());
1015 StringRef PerName = Per->getName();
1016 int BaseState = -1;
1017 if (PerName == "_except_handler4") {
1018 // The LSDA for _except_handler4 starts with this struct, followed by the
1019 // scope table:
1020 //
1021 // struct EH4ScopeTable {
1022 // int32_t GSCookieOffset;
1023 // int32_t GSCookieXOROffset;
1024 // int32_t EHCookieOffset;
1025 // int32_t EHCookieXOROffset;
1026 // ScopeTableEntry ScopeRecord[];
1027 // };
1028 //
1029 // Offsets are %ebp relative.
1030 //
1031 // The GS cookie is present only if the function needs stack protection.
1032 // GSCookieOffset = -2 means that GS cookie is not used.
1033 //
1034 // The EH cookie is always present.
1035 //
1036 // Check is done the following way:
1037 // (ebp+CookieXOROffset) ^ [ebp+CookieOffset] == _security_cookie
1038
1039 // Retrieve the Guard Stack slot.
1040 int GSCookieOffset = -2;
1041 const MachineFrameInfo &MFI = MF->getFrameInfo();
1042 if (MFI.hasStackProtectorIndex()) {
1043 Register UnusedReg;
1044 const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
1045 int SSPIdx = MFI.getStackProtectorIndex();
1046 GSCookieOffset =
1047 TFI->getFrameIndexReference(MF: *MF, FI: SSPIdx, FrameReg&: UnusedReg).getFixed();
1048 }
1049
1050 // Retrieve the EH Guard slot.
1051 // TODO(etienneb): Get rid of this value and change it for and assertion.
1052 int EHCookieOffset = 9999;
1053 if (FuncInfo.EHGuardFrameIndex != INT_MAX) {
1054 Register UnusedReg;
1055 const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
1056 int EHGuardIdx = FuncInfo.EHGuardFrameIndex;
1057 EHCookieOffset =
1058 TFI->getFrameIndexReference(MF: *MF, FI: EHGuardIdx, FrameReg&: UnusedReg).getFixed();
1059 }
1060
1061 AddComment("GSCookieOffset");
1062 OS.emitInt32(Value: GSCookieOffset);
1063 AddComment("GSCookieXOROffset");
1064 OS.emitInt32(Value: 0);
1065 AddComment("EHCookieOffset");
1066 OS.emitInt32(Value: EHCookieOffset);
1067 AddComment("EHCookieXOROffset");
1068 OS.emitInt32(Value: 0);
1069 BaseState = -2;
1070 }
1071
1072 assert(!FuncInfo.SEHUnwindMap.empty());
1073 for (const SEHUnwindMapEntry &UME : FuncInfo.SEHUnwindMap) {
1074 auto *Handler = cast<MachineBasicBlock *>(Val: UME.Handler);
1075 const MCSymbol *ExceptOrFinally =
1076 UME.IsFinally ? getMCSymbolForMBB(Asm, MBB: Handler) : Handler->getSymbol();
1077 // -1 is usually the base state for "unwind to caller", but for
1078 // _except_handler4 it's -2. Do that replacement here if necessary.
1079 int ToState = UME.ToState == -1 ? BaseState : UME.ToState;
1080 AddComment("ToState");
1081 OS.emitInt32(Value: ToState);
1082 AddComment(UME.IsFinally ? "Null" : "FilterFunction");
1083 OS.emitValue(Value: create32bitRef(GV: UME.Filter), Size: 4);
1084 AddComment(UME.IsFinally ? "FinallyFunclet" : "ExceptionHandler");
1085 OS.emitValue(Value: create32bitRef(Value: ExceptOrFinally), Size: 4);
1086 }
1087}
1088
1089static int getTryRank(const WinEHFuncInfo &FuncInfo, int State) {
1090 int Rank = 0;
1091 while (State != -1) {
1092 ++Rank;
1093 State = FuncInfo.ClrEHUnwindMap[State].TryParentState;
1094 }
1095 return Rank;
1096}
1097
1098static int getTryAncestor(const WinEHFuncInfo &FuncInfo, int Left, int Right) {
1099 int LeftRank = getTryRank(FuncInfo, State: Left);
1100 int RightRank = getTryRank(FuncInfo, State: Right);
1101
1102 while (LeftRank < RightRank) {
1103 Right = FuncInfo.ClrEHUnwindMap[Right].TryParentState;
1104 --RightRank;
1105 }
1106
1107 while (RightRank < LeftRank) {
1108 Left = FuncInfo.ClrEHUnwindMap[Left].TryParentState;
1109 --LeftRank;
1110 }
1111
1112 while (Left != Right) {
1113 Left = FuncInfo.ClrEHUnwindMap[Left].TryParentState;
1114 Right = FuncInfo.ClrEHUnwindMap[Right].TryParentState;
1115 }
1116
1117 return Left;
1118}
1119
1120void WinException::emitCLRExceptionTable(const MachineFunction *MF) {
1121 // CLR EH "states" are really just IDs that identify handlers/funclets;
1122 // states, handlers, and funclets all have 1:1 mappings between them, and a
1123 // handler/funclet's "state" is its index in the ClrEHUnwindMap.
1124 MCStreamer &OS = *Asm->OutStreamer;
1125 const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
1126 MCSymbol *FuncBeginSym = Asm->getFunctionBegin();
1127 MCSymbol *FuncEndSym = Asm->getFunctionEnd();
1128
1129 // A ClrClause describes a protected region.
1130 struct ClrClause {
1131 const MCSymbol *StartLabel; // Start of protected region
1132 const MCSymbol *EndLabel; // End of protected region
1133 int State; // Index of handler protecting the protected region
1134 int EnclosingState; // Index of funclet enclosing the protected region
1135 };
1136 SmallVector<ClrClause, 8> Clauses;
1137
1138 // Build a map from handler MBBs to their corresponding states (i.e. their
1139 // indices in the ClrEHUnwindMap).
1140 int NumStates = FuncInfo.ClrEHUnwindMap.size();
1141 assert(NumStates > 0 && "Don't need exception table!");
1142 DenseMap<const MachineBasicBlock *, int> HandlerStates;
1143 for (int State = 0; State < NumStates; ++State) {
1144 MachineBasicBlock *HandlerBlock =
1145 cast<MachineBasicBlock *>(Val: FuncInfo.ClrEHUnwindMap[State].Handler);
1146 HandlerStates[HandlerBlock] = State;
1147 // Use this loop through all handlers to verify our assumption (used in
1148 // the MinEnclosingState computation) that enclosing funclets have lower
1149 // state numbers than their enclosed funclets.
1150 assert(FuncInfo.ClrEHUnwindMap[State].HandlerParentState < State &&
1151 "ill-formed state numbering");
1152 }
1153 // Map the main function to the NullState.
1154 HandlerStates[&MF->front()] = NullState;
1155
1156 // Write out a sentinel indicating the end of the standard (Windows) xdata
1157 // and the start of the additional (CLR) info.
1158 OS.emitInt32(Value: 0xffffffff);
1159 // Write out the number of funclets
1160 OS.emitInt32(Value: NumStates);
1161
1162 // Walk the machine blocks/instrs, computing and emitting a few things:
1163 // 1. Emit a list of the offsets to each handler entry, in lexical order.
1164 // 2. Compute a map (EndSymbolMap) from each funclet to the symbol at its end.
1165 // 3. Compute the list of ClrClauses, in the required order (inner before
1166 // outer, earlier before later; the order by which a forward scan with
1167 // early termination will find the innermost enclosing clause covering
1168 // a given address).
1169 // 4. A map (MinClauseMap) from each handler index to the index of the
1170 // outermost funclet/function which contains a try clause targeting the
1171 // key handler. This will be used to determine IsDuplicate-ness when
1172 // emitting ClrClauses. The NullState value is used to indicate that the
1173 // top-level function contains a try clause targeting the key handler.
1174 // HandlerStack is a stack of (PendingStartLabel, PendingState) pairs for
1175 // try regions we entered before entering the PendingState try but which
1176 // we haven't yet exited.
1177 SmallVector<std::pair<const MCSymbol *, int>, 4> HandlerStack;
1178 // EndSymbolMap and MinClauseMap are maps described above.
1179 std::unique_ptr<MCSymbol *[]> EndSymbolMap(new MCSymbol *[NumStates]);
1180 SmallVector<int, 4> MinClauseMap((size_t)NumStates, NumStates);
1181
1182 // Visit the root function and each funclet.
1183 for (MachineFunction::const_iterator FuncletStart = MF->begin(),
1184 FuncletEnd = MF->begin(),
1185 End = MF->end();
1186 FuncletStart != End; FuncletStart = FuncletEnd) {
1187 int FuncletState = HandlerStates[&*FuncletStart];
1188 // Find the end of the funclet
1189 MCSymbol *EndSymbol = FuncEndSym;
1190 while (++FuncletEnd != End) {
1191 if (FuncletEnd->isEHFuncletEntry()) {
1192 EndSymbol = getMCSymbolForMBB(Asm, MBB: &*FuncletEnd);
1193 break;
1194 }
1195 }
1196 // Emit the function/funclet end and, if this is a funclet (and not the
1197 // root function), record it in the EndSymbolMap.
1198 OS.emitValue(Value: getOffset(OffsetOf: EndSymbol, OffsetFrom: FuncBeginSym), Size: 4);
1199 if (FuncletState != NullState) {
1200 // Record the end of the handler.
1201 EndSymbolMap[FuncletState] = EndSymbol;
1202 }
1203
1204 // Walk the state changes in this function/funclet and compute its clauses.
1205 // Funclets always start in the null state.
1206 const MCSymbol *CurrentStartLabel = nullptr;
1207 int CurrentState = NullState;
1208 assert(HandlerStack.empty());
1209 for (const auto &StateChange :
1210 InvokeStateChangeIterator::range(EHInfo: FuncInfo, Begin: FuncletStart, End: FuncletEnd)) {
1211 // Close any try regions we're not still under
1212 int StillPendingState =
1213 getTryAncestor(FuncInfo, Left: CurrentState, Right: StateChange.NewState);
1214 while (CurrentState != StillPendingState) {
1215 assert(CurrentState != NullState &&
1216 "Failed to find still-pending state!");
1217 // Close the pending clause
1218 Clauses.push_back(Elt: {.StartLabel: CurrentStartLabel, .EndLabel: StateChange.PreviousEndLabel,
1219 .State: CurrentState, .EnclosingState: FuncletState});
1220 // Now the next-outer try region is current
1221 CurrentState = FuncInfo.ClrEHUnwindMap[CurrentState].TryParentState;
1222 // Pop the new start label from the handler stack if we've exited all
1223 // inner try regions of the corresponding try region.
1224 if (HandlerStack.back().second == CurrentState)
1225 CurrentStartLabel = HandlerStack.pop_back_val().first;
1226 }
1227
1228 if (StateChange.NewState != CurrentState) {
1229 // For each clause we're starting, update the MinClauseMap so we can
1230 // know which is the topmost funclet containing a clause targeting
1231 // it.
1232 for (int EnteredState = StateChange.NewState;
1233 EnteredState != CurrentState;
1234 EnteredState =
1235 FuncInfo.ClrEHUnwindMap[EnteredState].TryParentState) {
1236 int &MinEnclosingState = MinClauseMap[EnteredState];
1237 if (FuncletState < MinEnclosingState)
1238 MinEnclosingState = FuncletState;
1239 }
1240 // Save the previous current start/label on the stack and update to
1241 // the newly-current start/state.
1242 HandlerStack.emplace_back(Args&: CurrentStartLabel, Args&: CurrentState);
1243 CurrentStartLabel = StateChange.NewStartLabel;
1244 CurrentState = StateChange.NewState;
1245 }
1246 }
1247 assert(HandlerStack.empty());
1248 }
1249
1250 // Now emit the clause info, starting with the number of clauses.
1251 OS.emitInt32(Value: Clauses.size());
1252 for (ClrClause &Clause : Clauses) {
1253 // Emit a CORINFO_EH_CLAUSE :
1254 /*
1255 struct CORINFO_EH_CLAUSE
1256 {
1257 CORINFO_EH_CLAUSE_FLAGS Flags; // actually a CorExceptionFlag
1258 DWORD TryOffset;
1259 DWORD TryLength; // actually TryEndOffset
1260 DWORD HandlerOffset;
1261 DWORD HandlerLength; // actually HandlerEndOffset
1262 union
1263 {
1264 DWORD ClassToken; // use for catch clauses
1265 DWORD FilterOffset; // use for filter clauses
1266 };
1267 };
1268
1269 enum CORINFO_EH_CLAUSE_FLAGS
1270 {
1271 CORINFO_EH_CLAUSE_NONE = 0,
1272 CORINFO_EH_CLAUSE_FILTER = 0x0001, // This clause is for a filter
1273 CORINFO_EH_CLAUSE_FINALLY = 0x0002, // This clause is a finally clause
1274 CORINFO_EH_CLAUSE_FAULT = 0x0004, // This clause is a fault clause
1275 };
1276 typedef enum CorExceptionFlag
1277 {
1278 COR_ILEXCEPTION_CLAUSE_NONE,
1279 COR_ILEXCEPTION_CLAUSE_FILTER = 0x0001, // This is a filter clause
1280 COR_ILEXCEPTION_CLAUSE_FINALLY = 0x0002, // This is a finally clause
1281 COR_ILEXCEPTION_CLAUSE_FAULT = 0x0004, // This is a fault clause
1282 COR_ILEXCEPTION_CLAUSE_DUPLICATED = 0x0008, // duplicated clause. This
1283 // clause was duplicated
1284 // to a funclet which was
1285 // pulled out of line
1286 } CorExceptionFlag;
1287 */
1288 // Add 1 to the start/end of the EH clause; the IP associated with a
1289 // call when the runtime does its scan is the IP of the next instruction
1290 // (the one to which control will return after the call), so we need
1291 // to add 1 to the end of the clause to cover that offset. We also add
1292 // 1 to the start of the clause to make sure that the ranges reported
1293 // for all clauses are disjoint. Note that we'll need some additional
1294 // logic when machine traps are supported, since in that case the IP
1295 // that the runtime uses is the offset of the faulting instruction
1296 // itself; if such an instruction immediately follows a call but the
1297 // two belong to different clauses, we'll need to insert a nop between
1298 // them so the runtime can distinguish the point to which the call will
1299 // return from the point at which the fault occurs.
1300
1301 const MCExpr *ClauseBegin =
1302 getOffsetPlusOne(OffsetOf: Clause.StartLabel, OffsetFrom: FuncBeginSym);
1303 const MCExpr *ClauseEnd = getOffsetPlusOne(OffsetOf: Clause.EndLabel, OffsetFrom: FuncBeginSym);
1304
1305 const ClrEHUnwindMapEntry &Entry = FuncInfo.ClrEHUnwindMap[Clause.State];
1306 MachineBasicBlock *HandlerBlock = cast<MachineBasicBlock *>(Val: Entry.Handler);
1307 MCSymbol *BeginSym = getMCSymbolForMBB(Asm, MBB: HandlerBlock);
1308 const MCExpr *HandlerBegin = getOffset(OffsetOf: BeginSym, OffsetFrom: FuncBeginSym);
1309 MCSymbol *EndSym = EndSymbolMap[Clause.State];
1310 const MCExpr *HandlerEnd = getOffset(OffsetOf: EndSym, OffsetFrom: FuncBeginSym);
1311
1312 uint32_t Flags = 0;
1313 switch (Entry.HandlerType) {
1314 case ClrHandlerType::Catch:
1315 // Leaving bits 0-2 clear indicates catch.
1316 break;
1317 case ClrHandlerType::Filter:
1318 Flags |= 1;
1319 break;
1320 case ClrHandlerType::Finally:
1321 Flags |= 2;
1322 break;
1323 case ClrHandlerType::Fault:
1324 Flags |= 4;
1325 break;
1326 }
1327 if (Clause.EnclosingState != MinClauseMap[Clause.State]) {
1328 // This is a "duplicate" clause; the handler needs to be entered from a
1329 // frame above the one holding the invoke.
1330 assert(Clause.EnclosingState > MinClauseMap[Clause.State]);
1331 Flags |= 8;
1332 }
1333 OS.emitInt32(Value: Flags);
1334
1335 // Write the clause start/end
1336 OS.emitValue(Value: ClauseBegin, Size: 4);
1337 OS.emitValue(Value: ClauseEnd, Size: 4);
1338
1339 // Write out the handler start/end
1340 OS.emitValue(Value: HandlerBegin, Size: 4);
1341 OS.emitValue(Value: HandlerEnd, Size: 4);
1342
1343 // Write out the type token or filter offset
1344 assert(Entry.HandlerType != ClrHandlerType::Filter && "NYI: filters");
1345 OS.emitInt32(Value: Entry.TypeToken);
1346 }
1347}
1348