LLVM  10.0.0svn
EHStreamer.cpp
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1 //===- CodeGen/AsmPrinter/EHStreamer.cpp - Exception Directive Streamer ---===//
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 exception info into assembly files.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "EHStreamer.h"
14 #include "llvm/ADT/SmallVector.h"
15 #include "llvm/ADT/Twine.h"
22 #include "llvm/IR/DataLayout.h"
23 #include "llvm/IR/Function.h"
24 #include "llvm/MC/MCAsmInfo.h"
25 #include "llvm/MC/MCContext.h"
26 #include "llvm/MC/MCStreamer.h"
27 #include "llvm/MC/MCSymbol.h"
29 #include "llvm/Support/Casting.h"
30 #include "llvm/Support/LEB128.h"
32 #include <algorithm>
33 #include <cassert>
34 #include <cstdint>
35 #include <vector>
36 
37 using namespace llvm;
38 
39 EHStreamer::EHStreamer(AsmPrinter *A) : Asm(A), MMI(Asm->MMI) {}
40 
41 EHStreamer::~EHStreamer() = default;
42 
43 /// How many leading type ids two landing pads have in common.
45  const LandingPadInfo *R) {
46  const std::vector<int> &LIds = L->TypeIds, &RIds = R->TypeIds;
47  unsigned LSize = LIds.size(), RSize = RIds.size();
48  unsigned MinSize = LSize < RSize ? LSize : RSize;
49  unsigned Count = 0;
50 
51  for (; Count != MinSize; ++Count)
52  if (LIds[Count] != RIds[Count])
53  return Count;
54 
55  return Count;
56 }
57 
58 /// Compute the actions table and gather the first action index for each landing
59 /// pad site.
61  const SmallVectorImpl<const LandingPadInfo *> &LandingPads,
63  SmallVectorImpl<unsigned> &FirstActions) {
64  // The action table follows the call-site table in the LSDA. The individual
65  // records are of two types:
66  //
67  // * Catch clause
68  // * Exception specification
69  //
70  // The two record kinds have the same format, with only small differences.
71  // They are distinguished by the "switch value" field: Catch clauses
72  // (TypeInfos) have strictly positive switch values, and exception
73  // specifications (FilterIds) have strictly negative switch values. Value 0
74  // indicates a catch-all clause.
75  //
76  // Negative type IDs index into FilterIds. Positive type IDs index into
77  // TypeInfos. The value written for a positive type ID is just the type ID
78  // itself. For a negative type ID, however, the value written is the
79  // (negative) byte offset of the corresponding FilterIds entry. The byte
80  // offset is usually equal to the type ID (because the FilterIds entries are
81  // written using a variable width encoding, which outputs one byte per entry
82  // as long as the value written is not too large) but can differ. This kind
83  // of complication does not occur for positive type IDs because type infos are
84  // output using a fixed width encoding. FilterOffsets[i] holds the byte
85  // offset corresponding to FilterIds[i].
86 
87  const std::vector<unsigned> &FilterIds = Asm->MF->getFilterIds();
88  SmallVector<int, 16> FilterOffsets;
89  FilterOffsets.reserve(FilterIds.size());
90  int Offset = -1;
91 
92  for (std::vector<unsigned>::const_iterator
93  I = FilterIds.begin(), E = FilterIds.end(); I != E; ++I) {
94  FilterOffsets.push_back(Offset);
95  Offset -= getULEB128Size(*I);
96  }
97 
98  FirstActions.reserve(LandingPads.size());
99 
100  int FirstAction = 0;
101  unsigned SizeActions = 0; // Total size of all action entries for a function
102  const LandingPadInfo *PrevLPI = nullptr;
103 
105  I = LandingPads.begin(), E = LandingPads.end(); I != E; ++I) {
106  const LandingPadInfo *LPI = *I;
107  const std::vector<int> &TypeIds = LPI->TypeIds;
108  unsigned NumShared = PrevLPI ? sharedTypeIDs(LPI, PrevLPI) : 0;
109  unsigned SizeSiteActions = 0; // Total size of all entries for a landingpad
110 
111  if (NumShared < TypeIds.size()) {
112  // Size of one action entry (typeid + next action)
113  unsigned SizeActionEntry = 0;
114  unsigned PrevAction = (unsigned)-1;
115 
116  if (NumShared) {
117  unsigned SizePrevIds = PrevLPI->TypeIds.size();
118  assert(Actions.size());
119  PrevAction = Actions.size() - 1;
120  SizeActionEntry = getSLEB128Size(Actions[PrevAction].NextAction) +
121  getSLEB128Size(Actions[PrevAction].ValueForTypeID);
122 
123  for (unsigned j = NumShared; j != SizePrevIds; ++j) {
124  assert(PrevAction != (unsigned)-1 && "PrevAction is invalid!");
125  SizeActionEntry -= getSLEB128Size(Actions[PrevAction].ValueForTypeID);
126  SizeActionEntry += -Actions[PrevAction].NextAction;
127  PrevAction = Actions[PrevAction].Previous;
128  }
129  }
130 
131  // Compute the actions.
132  for (unsigned J = NumShared, M = TypeIds.size(); J != M; ++J) {
133  int TypeID = TypeIds[J];
134  assert(-1 - TypeID < (int)FilterOffsets.size() && "Unknown filter id!");
135  int ValueForTypeID =
136  isFilterEHSelector(TypeID) ? FilterOffsets[-1 - TypeID] : TypeID;
137  unsigned SizeTypeID = getSLEB128Size(ValueForTypeID);
138 
139  int NextAction = SizeActionEntry ? -(SizeActionEntry + SizeTypeID) : 0;
140  SizeActionEntry = SizeTypeID + getSLEB128Size(NextAction);
141  SizeSiteActions += SizeActionEntry;
142 
143  ActionEntry Action = { ValueForTypeID, NextAction, PrevAction };
144  Actions.push_back(Action);
145  PrevAction = Actions.size() - 1;
146  }
147 
148  // Record the first action of the landing pad site.
149  FirstAction = SizeActions + SizeSiteActions - SizeActionEntry + 1;
150  } // else identical - re-use previous FirstAction
151 
152  // Information used when creating the call-site table. The action record
153  // field of the call site record is the offset of the first associated
154  // action record, relative to the start of the actions table. This value is
155  // biased by 1 (1 indicating the start of the actions table), and 0
156  // indicates that there are no actions.
157  FirstActions.push_back(FirstAction);
158 
159  // Compute this sites contribution to size.
160  SizeActions += SizeSiteActions;
161 
162  PrevLPI = LPI;
163  }
164 }
165 
166 /// Return `true' if this is a call to a function marked `nounwind'. Return
167 /// `false' otherwise.
169  assert(MI->isCall() && "This should be a call instruction!");
170 
171  bool MarkedNoUnwind = false;
172  bool SawFunc = false;
173 
174  for (unsigned I = 0, E = MI->getNumOperands(); I != E; ++I) {
175  const MachineOperand &MO = MI->getOperand(I);
176 
177  if (!MO.isGlobal()) continue;
178 
179  const Function *F = dyn_cast<Function>(MO.getGlobal());
180  if (!F) continue;
181 
182  if (SawFunc) {
183  // Be conservative. If we have more than one function operand for this
184  // call, then we can't make the assumption that it's the callee and
185  // not a parameter to the call.
186  //
187  // FIXME: Determine if there's a way to say that `F' is the callee or
188  // parameter.
189  MarkedNoUnwind = false;
190  break;
191  }
192 
193  MarkedNoUnwind = F->doesNotThrow();
194  SawFunc = true;
195  }
196 
197  return MarkedNoUnwind;
198 }
199 
201  const SmallVectorImpl<const LandingPadInfo *> &LandingPads,
202  RangeMapType &PadMap) {
203  // Invokes and nounwind calls have entries in PadMap (due to being bracketed
204  // by try-range labels when lowered). Ordinary calls do not, so appropriate
205  // try-ranges for them need be deduced so we can put them in the LSDA.
206  for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
207  const LandingPadInfo *LandingPad = LandingPads[i];
208  for (unsigned j = 0, E = LandingPad->BeginLabels.size(); j != E; ++j) {
209  MCSymbol *BeginLabel = LandingPad->BeginLabels[j];
210  assert(!PadMap.count(BeginLabel) && "Duplicate landing pad labels!");
211  PadRange P = { i, j };
212  PadMap[BeginLabel] = P;
213  }
214  }
215 }
216 
217 /// Compute the call-site table. The entry for an invoke has a try-range
218 /// containing the call, a non-zero landing pad, and an appropriate action. The
219 /// entry for an ordinary call has a try-range containing the call and zero for
220 /// the landing pad and the action. Calls marked 'nounwind' have no entry and
221 /// must not be contained in the try-range of any entry - they form gaps in the
222 /// table. Entries must be ordered by try-range address.
223 void EHStreamer::
225  const SmallVectorImpl<const LandingPadInfo *> &LandingPads,
226  const SmallVectorImpl<unsigned> &FirstActions) {
227  RangeMapType PadMap;
228  computePadMap(LandingPads, PadMap);
229 
230  // The end label of the previous invoke or nounwind try-range.
231  MCSymbol *LastLabel = nullptr;
232 
233  // Whether there is a potentially throwing instruction (currently this means
234  // an ordinary call) between the end of the previous try-range and now.
235  bool SawPotentiallyThrowing = false;
236 
237  // Whether the last CallSite entry was for an invoke.
238  bool PreviousIsInvoke = false;
239 
241 
242  // Visit all instructions in order of address.
243  for (const auto &MBB : *Asm->MF) {
244  for (const auto &MI : MBB) {
245  if (!MI.isEHLabel()) {
246  if (MI.isCall())
247  SawPotentiallyThrowing |= !callToNoUnwindFunction(&MI);
248  continue;
249  }
250 
251  // End of the previous try-range?
252  MCSymbol *BeginLabel = MI.getOperand(0).getMCSymbol();
253  if (BeginLabel == LastLabel)
254  SawPotentiallyThrowing = false;
255 
256  // Beginning of a new try-range?
257  RangeMapType::const_iterator L = PadMap.find(BeginLabel);
258  if (L == PadMap.end())
259  // Nope, it was just some random label.
260  continue;
261 
262  const PadRange &P = L->second;
263  const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
264  assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
265  "Inconsistent landing pad map!");
266 
267  // For Dwarf exception handling (SjLj handling doesn't use this). If some
268  // instruction between the previous try-range and this one may throw,
269  // create a call-site entry with no landing pad for the region between the
270  // try-ranges.
271  if (SawPotentiallyThrowing && Asm->MAI->usesCFIForEH()) {
272  CallSiteEntry Site = { LastLabel, BeginLabel, nullptr, 0 };
273  CallSites.push_back(Site);
274  PreviousIsInvoke = false;
275  }
276 
277  LastLabel = LandingPad->EndLabels[P.RangeIndex];
278  assert(BeginLabel && LastLabel && "Invalid landing pad!");
279 
280  if (!LandingPad->LandingPadLabel) {
281  // Create a gap.
282  PreviousIsInvoke = false;
283  } else {
284  // This try-range is for an invoke.
285  CallSiteEntry Site = {
286  BeginLabel,
287  LastLabel,
288  LandingPad,
289  FirstActions[P.PadIndex]
290  };
291 
292  // Try to merge with the previous call-site. SJLJ doesn't do this
293  if (PreviousIsInvoke && !IsSJLJ) {
294  CallSiteEntry &Prev = CallSites.back();
295  if (Site.LPad == Prev.LPad && Site.Action == Prev.Action) {
296  // Extend the range of the previous entry.
297  Prev.EndLabel = Site.EndLabel;
298  continue;
299  }
300  }
301 
302  // Otherwise, create a new call-site.
303  if (!IsSJLJ)
304  CallSites.push_back(Site);
305  else {
306  // SjLj EH must maintain the call sites in the order assigned
307  // to them by the SjLjPrepare pass.
308  unsigned SiteNo = Asm->MF->getCallSiteBeginLabel(BeginLabel);
309  if (CallSites.size() < SiteNo)
310  CallSites.resize(SiteNo);
311  CallSites[SiteNo - 1] = Site;
312  }
313  PreviousIsInvoke = true;
314  }
315  }
316  }
317 
318  // If some instruction between the previous try-range and the end of the
319  // function may throw, create a call-site entry with no landing pad for the
320  // region following the try-range.
321  if (SawPotentiallyThrowing && !IsSJLJ) {
322  CallSiteEntry Site = { LastLabel, nullptr, nullptr, 0 };
323  CallSites.push_back(Site);
324  }
325 }
326 
327 /// Emit landing pads and actions.
328 ///
329 /// The general organization of the table is complex, but the basic concepts are
330 /// easy. First there is a header which describes the location and organization
331 /// of the three components that follow.
332 ///
333 /// 1. The landing pad site information describes the range of code covered by
334 /// the try. In our case it's an accumulation of the ranges covered by the
335 /// invokes in the try. There is also a reference to the landing pad that
336 /// handles the exception once processed. Finally an index into the actions
337 /// table.
338 /// 2. The action table, in our case, is composed of pairs of type IDs and next
339 /// action offset. Starting with the action index from the landing pad
340 /// site, each type ID is checked for a match to the current exception. If
341 /// it matches then the exception and type id are passed on to the landing
342 /// pad. Otherwise the next action is looked up. This chain is terminated
343 /// with a next action of zero. If no type id is found then the frame is
344 /// unwound and handling continues.
345 /// 3. Type ID table contains references to all the C++ typeinfo for all
346 /// catches in the function. This tables is reverse indexed base 1.
347 ///
348 /// Returns the starting symbol of an exception table.
350  const MachineFunction *MF = Asm->MF;
351  const std::vector<const GlobalValue *> &TypeInfos = MF->getTypeInfos();
352  const std::vector<unsigned> &FilterIds = MF->getFilterIds();
353  const std::vector<LandingPadInfo> &PadInfos = MF->getLandingPads();
354 
355  // Sort the landing pads in order of their type ids. This is used to fold
356  // duplicate actions.
358  LandingPads.reserve(PadInfos.size());
359 
360  for (unsigned i = 0, N = PadInfos.size(); i != N; ++i)
361  LandingPads.push_back(&PadInfos[i]);
362 
363  // Order landing pads lexicographically by type id.
364  llvm::sort(LandingPads, [](const LandingPadInfo *L, const LandingPadInfo *R) {
365  return L->TypeIds < R->TypeIds;
366  });
367 
368  // Compute the actions table and gather the first action index for each
369  // landing pad site.
371  SmallVector<unsigned, 64> FirstActions;
372  computeActionsTable(LandingPads, Actions, FirstActions);
373 
374  // Compute the call-site table.
376  computeCallSiteTable(CallSites, LandingPads, FirstActions);
377 
380  unsigned CallSiteEncoding =
381  IsSJLJ ? static_cast<unsigned>(dwarf::DW_EH_PE_udata4) :
383  bool HaveTTData = !TypeInfos.empty() || !FilterIds.empty();
384 
385  // Type infos.
386  MCSection *LSDASection = Asm->getObjFileLowering().getLSDASection();
387  unsigned TTypeEncoding;
388 
389  if (!HaveTTData) {
390  // If there is no TypeInfo, then we just explicitly say that we're omitting
391  // that bit.
392  TTypeEncoding = dwarf::DW_EH_PE_omit;
393  } else {
394  // Okay, we have actual filters or typeinfos to emit. As such, we need to
395  // pick a type encoding for them. We're about to emit a list of pointers to
396  // typeinfo objects at the end of the LSDA. However, unless we're in static
397  // mode, this reference will require a relocation by the dynamic linker.
398  //
399  // Because of this, we have a couple of options:
400  //
401  // 1) If we are in -static mode, we can always use an absolute reference
402  // from the LSDA, because the static linker will resolve it.
403  //
404  // 2) Otherwise, if the LSDA section is writable, we can output the direct
405  // reference to the typeinfo and allow the dynamic linker to relocate
406  // it. Since it is in a writable section, the dynamic linker won't
407  // have a problem.
408  //
409  // 3) Finally, if we're in PIC mode and the LDSA section isn't writable,
410  // we need to use some form of indirection. For example, on Darwin,
411  // we can output a statically-relocatable reference to a dyld stub. The
412  // offset to the stub is constant, but the contents are in a section
413  // that is updated by the dynamic linker. This is easy enough, but we
414  // need to tell the personality function of the unwinder to indirect
415  // through the dyld stub.
416  //
417  // FIXME: When (3) is actually implemented, we'll have to emit the stubs
418  // somewhere. This predicate should be moved to a shared location that is
419  // in target-independent code.
420  //
421  TTypeEncoding = Asm->getObjFileLowering().getTTypeEncoding();
422  }
423 
424  // Begin the exception table.
425  // Sometimes we want not to emit the data into separate section (e.g. ARM
426  // EHABI). In this case LSDASection will be NULL.
427  if (LSDASection)
428  Asm->OutStreamer->SwitchSection(LSDASection);
429  Asm->EmitAlignment(2);
430 
431  // Emit the LSDA.
432  MCSymbol *GCCETSym =
433  Asm->OutContext.getOrCreateSymbol(Twine("GCC_except_table")+
435  Asm->OutStreamer->EmitLabel(GCCETSym);
436  Asm->OutStreamer->EmitLabel(Asm->getCurExceptionSym());
437 
438  // Emit the LSDA header.
440  Asm->EmitEncodingByte(TTypeEncoding, "@TType");
441 
442  MCSymbol *TTBaseLabel = nullptr;
443  if (HaveTTData) {
444  // N.B.: There is a dependency loop between the size of the TTBase uleb128
445  // here and the amount of padding before the aligned type table. The
446  // assembler must sometimes pad this uleb128 or insert extra padding before
447  // the type table. See PR35809 or GNU as bug 4029.
448  MCSymbol *TTBaseRefLabel = Asm->createTempSymbol("ttbaseref");
449  TTBaseLabel = Asm->createTempSymbol("ttbase");
450  Asm->EmitLabelDifferenceAsULEB128(TTBaseLabel, TTBaseRefLabel);
451  Asm->OutStreamer->EmitLabel(TTBaseRefLabel);
452  }
453 
454  bool VerboseAsm = Asm->OutStreamer->isVerboseAsm();
455 
456  // Emit the landing pad call site table.
457  MCSymbol *CstBeginLabel = Asm->createTempSymbol("cst_begin");
458  MCSymbol *CstEndLabel = Asm->createTempSymbol("cst_end");
459  Asm->EmitEncodingByte(CallSiteEncoding, "Call site");
460  Asm->EmitLabelDifferenceAsULEB128(CstEndLabel, CstBeginLabel);
461  Asm->OutStreamer->EmitLabel(CstBeginLabel);
462 
463  // SjLj / Wasm Exception handling
464  if (IsSJLJ || IsWasm) {
465  unsigned idx = 0;
467  I = CallSites.begin(), E = CallSites.end(); I != E; ++I, ++idx) {
468  const CallSiteEntry &S = *I;
469 
470  // Index of the call site entry.
471  if (VerboseAsm) {
472  Asm->OutStreamer->AddComment(">> Call Site " + Twine(idx) + " <<");
473  Asm->OutStreamer->AddComment(" On exception at call site "+Twine(idx));
474  }
475  Asm->EmitULEB128(idx);
476 
477  // Offset of the first associated action record, relative to the start of
478  // the action table. This value is biased by 1 (1 indicates the start of
479  // the action table), and 0 indicates that there are no actions.
480  if (VerboseAsm) {
481  if (S.Action == 0)
482  Asm->OutStreamer->AddComment(" Action: cleanup");
483  else
484  Asm->OutStreamer->AddComment(" Action: " +
485  Twine((S.Action - 1) / 2 + 1));
486  }
487  Asm->EmitULEB128(S.Action);
488  }
489  } else {
490  // Itanium LSDA exception handling
491 
492  // The call-site table is a list of all call sites that may throw an
493  // exception (including C++ 'throw' statements) in the procedure
494  // fragment. It immediately follows the LSDA header. Each entry indicates,
495  // for a given call, the first corresponding action record and corresponding
496  // landing pad.
497  //
498  // The table begins with the number of bytes, stored as an LEB128
499  // compressed, unsigned integer. The records immediately follow the record
500  // count. They are sorted in increasing call-site address. Each record
501  // indicates:
502  //
503  // * The position of the call-site.
504  // * The position of the landing pad.
505  // * The first action record for that call site.
506  //
507  // A missing entry in the call-site table indicates that a call is not
508  // supposed to throw.
509 
510  unsigned Entry = 0;
512  I = CallSites.begin(), E = CallSites.end(); I != E; ++I) {
513  const CallSiteEntry &S = *I;
514 
515  MCSymbol *EHFuncBeginSym = Asm->getFunctionBegin();
516 
517  MCSymbol *BeginLabel = S.BeginLabel;
518  if (!BeginLabel)
519  BeginLabel = EHFuncBeginSym;
520  MCSymbol *EndLabel = S.EndLabel;
521  if (!EndLabel)
522  EndLabel = Asm->getFunctionEnd();
523 
524  // Offset of the call site relative to the start of the procedure.
525  if (VerboseAsm)
526  Asm->OutStreamer->AddComment(">> Call Site " + Twine(++Entry) + " <<");
527  Asm->EmitCallSiteOffset(BeginLabel, EHFuncBeginSym, CallSiteEncoding);
528  if (VerboseAsm)
529  Asm->OutStreamer->AddComment(Twine(" Call between ") +
530  BeginLabel->getName() + " and " +
531  EndLabel->getName());
532  Asm->EmitCallSiteOffset(EndLabel, BeginLabel, CallSiteEncoding);
533 
534  // Offset of the landing pad relative to the start of the procedure.
535  if (!S.LPad) {
536  if (VerboseAsm)
537  Asm->OutStreamer->AddComment(" has no landing pad");
538  Asm->EmitCallSiteValue(0, CallSiteEncoding);
539  } else {
540  if (VerboseAsm)
541  Asm->OutStreamer->AddComment(Twine(" jumps to ") +
543  Asm->EmitCallSiteOffset(S.LPad->LandingPadLabel, EHFuncBeginSym,
544  CallSiteEncoding);
545  }
546 
547  // Offset of the first associated action record, relative to the start of
548  // the action table. This value is biased by 1 (1 indicates the start of
549  // the action table), and 0 indicates that there are no actions.
550  if (VerboseAsm) {
551  if (S.Action == 0)
552  Asm->OutStreamer->AddComment(" On action: cleanup");
553  else
554  Asm->OutStreamer->AddComment(" On action: " +
555  Twine((S.Action - 1) / 2 + 1));
556  }
557  Asm->EmitULEB128(S.Action);
558  }
559  }
560  Asm->OutStreamer->EmitLabel(CstEndLabel);
561 
562  // Emit the Action Table.
563  int Entry = 0;
565  I = Actions.begin(), E = Actions.end(); I != E; ++I) {
566  const ActionEntry &Action = *I;
567 
568  if (VerboseAsm) {
569  // Emit comments that decode the action table.
570  Asm->OutStreamer->AddComment(">> Action Record " + Twine(++Entry) + " <<");
571  }
572 
573  // Type Filter
574  //
575  // Used by the runtime to match the type of the thrown exception to the
576  // type of the catch clauses or the types in the exception specification.
577  if (VerboseAsm) {
578  if (Action.ValueForTypeID > 0)
579  Asm->OutStreamer->AddComment(" Catch TypeInfo " +
580  Twine(Action.ValueForTypeID));
581  else if (Action.ValueForTypeID < 0)
582  Asm->OutStreamer->AddComment(" Filter TypeInfo " +
583  Twine(Action.ValueForTypeID));
584  else
585  Asm->OutStreamer->AddComment(" Cleanup");
586  }
587  Asm->EmitSLEB128(Action.ValueForTypeID);
588 
589  // Action Record
590  //
591  // Self-relative signed displacement in bytes of the next action record,
592  // or 0 if there is no next action record.
593  if (VerboseAsm) {
594  if (Action.NextAction == 0) {
595  Asm->OutStreamer->AddComment(" No further actions");
596  } else {
597  unsigned NextAction = Entry + (Action.NextAction + 1) / 2;
598  Asm->OutStreamer->AddComment(" Continue to action "+Twine(NextAction));
599  }
600  }
601  Asm->EmitSLEB128(Action.NextAction);
602  }
603 
604  if (HaveTTData) {
605  Asm->EmitAlignment(2);
606  emitTypeInfos(TTypeEncoding, TTBaseLabel);
607  }
608 
609  Asm->EmitAlignment(2);
610  return GCCETSym;
611 }
612 
613 void EHStreamer::emitTypeInfos(unsigned TTypeEncoding, MCSymbol *TTBaseLabel) {
614  const MachineFunction *MF = Asm->MF;
615  const std::vector<const GlobalValue *> &TypeInfos = MF->getTypeInfos();
616  const std::vector<unsigned> &FilterIds = MF->getFilterIds();
617 
618  bool VerboseAsm = Asm->OutStreamer->isVerboseAsm();
619 
620  int Entry = 0;
621  // Emit the Catch TypeInfos.
622  if (VerboseAsm && !TypeInfos.empty()) {
623  Asm->OutStreamer->AddComment(">> Catch TypeInfos <<");
624  Asm->OutStreamer->AddBlankLine();
625  Entry = TypeInfos.size();
626  }
627 
628  for (const GlobalValue *GV : make_range(TypeInfos.rbegin(),
629  TypeInfos.rend())) {
630  if (VerboseAsm)
631  Asm->OutStreamer->AddComment("TypeInfo " + Twine(Entry--));
632  Asm->EmitTTypeReference(GV, TTypeEncoding);
633  }
634 
635  Asm->OutStreamer->EmitLabel(TTBaseLabel);
636 
637  // Emit the Exception Specifications.
638  if (VerboseAsm && !FilterIds.empty()) {
639  Asm->OutStreamer->AddComment(">> Filter TypeInfos <<");
640  Asm->OutStreamer->AddBlankLine();
641  Entry = 0;
642  }
643  for (std::vector<unsigned>::const_iterator
644  I = FilterIds.begin(), E = FilterIds.end(); I < E; ++I) {
645  unsigned TypeID = *I;
646  if (VerboseAsm) {
647  --Entry;
648  if (isFilterEHSelector(TypeID))
649  Asm->OutStreamer->AddComment("FilterInfo " + Twine(Entry));
650  }
651 
652  Asm->EmitULEB128(TypeID);
653  }
654 }
void EmitCallSiteOffset(const MCSymbol *Hi, const MCSymbol *Lo, unsigned Encoding) const
Emit reference to a call site with a specified encoding.
const TargetLoweringObjectFile & getObjFileLowering() const
Return information about object file lowering.
Definition: AsmPrinter.cpp:215
Instances of this class represent a uniqued identifier for a section in the current translation unit...
Definition: MCSection.h:38
static unsigned sharedTypeIDs(const LandingPadInfo *L, const LandingPadInfo *R)
How many leading type ids two landing pads have in common.
Definition: EHStreamer.cpp:44
Structure describing an entry in the call-site table.
Definition: EHStreamer.h:61
bool isCall(QueryType Type=AnyInBundle) const
Definition: MachineInstr.h:651
typename SuperClass::const_iterator const_iterator
Definition: SmallVector.h:320
std::unique_ptr< MCStreamer > OutStreamer
This is the MCStreamer object for the file we are generating.
Definition: AsmPrinter.h:93
This class represents lattice values for constants.
Definition: AllocatorList.h:23
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:41
MCContext & OutContext
This is the context for the output file that we are streaming.
Definition: AsmPrinter.h:88
setjmp/longjmp based exceptions
EHStreamer(AsmPrinter *A)
Definition: EHStreamer.cpp:39
This provides a very simple, boring adaptor for a begin and end iterator into a range type...
static bool callToNoUnwindFunction(const MachineInstr *MI)
Return `true&#39; if this is a call to a function marked `nounwind&#39;.
Definition: EHStreamer.cpp:168
unsigned getCallSiteBeginLabel(MCSymbol *BeginLabel) const
Get the call site number for a begin label.
F(f)
MachineFunction * MF
The current machine function.
Definition: AsmPrinter.h:96
Structure describing an entry in the actions table.
Definition: EHStreamer.h:54
void reserve(size_type N)
Definition: SmallVector.h:369
static bool isFilterEHSelector(int Selector)
Definition: EHStreamer.h:120
const LandingPadInfo * LPad
Definition: EHStreamer.h:67
const std::vector< unsigned > & getFilterIds() const
Return a reference to the typeids encoding filters used in the current function.
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:80
SmallVector< MCSymbol *, 1 > EndLabels
unsigned getNumOperands() const
Retuns the total number of operands.
Definition: MachineInstr.h:414
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APFloat.h:41
void computeActionsTable(const SmallVectorImpl< const LandingPadInfo *> &LandingPads, SmallVectorImpl< ActionEntry > &Actions, SmallVectorImpl< unsigned > &FirstActions)
Compute the actions table and gather the first action index for each landing pad site.
Definition: EHStreamer.cpp:60
TypeID
Definitions of all of the base types for the Type system.
Definition: Type.h:54
~EHStreamer() override
This structure is used to retain landing pad info for the current function.
MCSymbol * getFunctionBegin() const
Definition: AsmPrinter.h:208
void EmitLabelDifferenceAsULEB128(const MCSymbol *Hi, const MCSymbol *Lo) const
Emit something like ".uleb128 Hi-Lo".
iterator find(const_arg_type_t< KeyT > Val)
Definition: DenseMap.h:176
WebAssembly Exception Handling.
#define P(N)
const MCAsmInfo * MAI
Target Asm Printer information.
Definition: AsmPrinter.h:84
void EmitULEB128(uint64_t Value, const char *Desc=nullptr, unsigned PadTo=0) const
Emit the specified unsigned leb128 value.
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
SmallVector< MCSymbol *, 1 > BeginLabels
const GlobalValue * getGlobal() const
void EmitEncodingByte(unsigned Val, const char *Desc=nullptr) const
Emit a .byte 42 directive that corresponds to an encoding.
void EmitAlignment(unsigned NumBits, const GlobalObject *GV=nullptr) const
Emit an alignment directive to the specified power of two boundary.
This class is intended to be used as a driving class for all asm writers.
Definition: AsmPrinter.h:78
Type::TypeID TypeID
std::vector< int > TypeIds
void EmitCallSiteValue(uint64_t Value, unsigned Encoding) const
Emit an integer value corresponding to the call site encoding.
size_t size() const
Definition: SmallVector.h:52
AsmPrinter * Asm
Target of directive emission.
Definition: EHStreamer.h:33
unsigned getULEB128Size(uint64_t Value)
Utility function to get the size of the ULEB128-encoded value.
Definition: LEB128.cpp:19
void sort(IteratorTy Start, IteratorTy End)
Definition: STLExtras.h:1095
bool doesNotThrow() const
Determine if the function cannot unwind.
Definition: Function.h:533
iterator_range< T > make_range(T x, T y)
Convenience function for iterating over sub-ranges.
unsigned getFunctionNumber() const
Return a unique ID for the current function.
Definition: AsmPrinter.cpp:211
const std::vector< LandingPadInfo > & getLandingPads() const
Return a reference to the landing pad info for the current function.
void EmitSLEB128(int64_t Value, const char *Desc=nullptr) const
Emit the specified signed leb128 value.
bool isGlobal() const
isGlobal - Tests if this is a MO_GlobalAddress operand.
MachineOperand class - Representation of each machine instruction operand.
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
virtual void emitTypeInfos(unsigned TTypeEncoding, MCSymbol *TTBaseLabel)
Definition: EHStreamer.cpp:613
void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const
Emit reference to a ttype global with a specified encoding.
MCSymbol * getFunctionEnd() const
Definition: AsmPrinter.h:209
bool usesCFIForEH() const
Returns true if the exception handling method for the platform uses call frame information to unwind...
Definition: MCAsmInfo.h:593
virtual void computeCallSiteTable(SmallVectorImpl< CallSiteEntry > &CallSites, const SmallVectorImpl< const LandingPadInfo *> &LandingPads, const SmallVectorImpl< unsigned > &FirstActions)
Compute the call-site table.
Definition: EHStreamer.cpp:224
This file contains constants used for implementing Dwarf debug support.
MCSymbol * getCurExceptionSym()
void computePadMap(const SmallVectorImpl< const LandingPadInfo *> &LandingPads, RangeMapType &PadMap)
Definition: EHStreamer.cpp:200
Representation of each machine instruction.
Definition: MachineInstr.h:64
MCSymbol * getOrCreateSymbol(const Twine &Name)
Lookup the symbol inside with the specified Name.
Definition: MCContext.cpp:129
#define I(x, y, z)
Definition: MD5.cpp:58
#define N
iterator end()
Definition: DenseMap.h:108
LLVM_NODISCARD std::enable_if<!is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:332
size_type count(const_arg_type_t< KeyT > Val) const
Return 1 if the specified key is in the map, 0 otherwise.
Definition: DenseMap.h:171
unsigned getSLEB128Size(int64_t Value)
Utility function to get the size of the SLEB128-encoded value.
Definition: LEB128.cpp:29
StringRef getName() const
getName - Get the symbol name.
Definition: MCSymbol.h:204
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
MCSymbol * emitExceptionTable()
Emit landing pads and actions.
Definition: EHStreamer.cpp:349
ExceptionHandling getExceptionHandlingType() const
Definition: MCAsmInfo.h:584
MCSection * getLSDASection() const
IRTranslator LLVM IR MI
const std::vector< const GlobalValue * > & getTypeInfos() const
Return a reference to the C++ typeinfo for the current function.
const MachineOperand & getOperand(unsigned i) const
Definition: MachineInstr.h:416
Structure holding a try-range and the associated landing pad.
Definition: EHStreamer.h:43
MCSymbol * createTempSymbol(const Twine &Name) const
void resize(size_type N)
Definition: SmallVector.h:344