1 //===-- CodeGen/AsmPrinter/DwarfException.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 DWARF exception info into asm files.
12 //===----------------------------------------------------------------------===//
14 #include "DwarfException.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/IR/DataLayout.h"
23 #include "llvm/IR/Mangler.h"
24 #include "llvm/IR/Module.h"
25 #include "llvm/MC/MCAsmInfo.h"
26 #include "llvm/MC/MCContext.h"
27 #include "llvm/MC/MCExpr.h"
28 #include "llvm/MC/MCSection.h"
29 #include "llvm/MC/MCStreamer.h"
30 #include "llvm/MC/MCSymbol.h"
31 #include "llvm/Support/Dwarf.h"
32 #include "llvm/Support/ErrorHandling.h"
33 #include "llvm/Support/FormattedStream.h"
34 #include "llvm/Support/LEB128.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 DwarfException::DwarfException(AsmPrinter *A)
42 : Asm(A), MMI(Asm->MMI) {}
44 DwarfException::~DwarfException() {}
46 /// SharedTypeIds - How many leading type ids two landing pads have in common.
47 unsigned DwarfException::SharedTypeIds(const LandingPadInfo *L,
48 const LandingPadInfo *R) {
49 const std::vector<int> &LIds = L->TypeIds, &RIds = R->TypeIds;
50 unsigned LSize = LIds.size(), RSize = RIds.size();
51 unsigned MinSize = LSize < RSize ? LSize : RSize;
54 for (; Count != MinSize; ++Count)
55 if (LIds[Count] != RIds[Count])
61 /// PadLT - Order landing pads lexicographically by type id.
62 bool DwarfException::PadLT(const LandingPadInfo *L, const LandingPadInfo *R) {
63 const std::vector<int> &LIds = L->TypeIds, &RIds = R->TypeIds;
64 unsigned LSize = LIds.size(), RSize = RIds.size();
65 unsigned MinSize = LSize < RSize ? LSize : RSize;
67 for (unsigned i = 0; i != MinSize; ++i)
68 if (LIds[i] != RIds[i])
69 return LIds[i] < RIds[i];
74 /// ComputeActionsTable - Compute the actions table and gather the first action
75 /// index for each landing pad site.
76 unsigned DwarfException::
77 ComputeActionsTable(const SmallVectorImpl<const LandingPadInfo*> &LandingPads,
78 SmallVectorImpl<ActionEntry> &Actions,
79 SmallVectorImpl<unsigned> &FirstActions) {
81 // The action table follows the call-site table in the LSDA. The individual
82 // records are of two types:
85 // * Exception specification
87 // The two record kinds have the same format, with only small differences.
88 // They are distinguished by the "switch value" field: Catch clauses
89 // (TypeInfos) have strictly positive switch values, and exception
90 // specifications (FilterIds) have strictly negative switch values. Value 0
91 // indicates a catch-all clause.
93 // Negative type IDs index into FilterIds. Positive type IDs index into
94 // TypeInfos. The value written for a positive type ID is just the type ID
95 // itself. For a negative type ID, however, the value written is the
96 // (negative) byte offset of the corresponding FilterIds entry. The byte
97 // offset is usually equal to the type ID (because the FilterIds entries are
98 // written using a variable width encoding, which outputs one byte per entry
99 // as long as the value written is not too large) but can differ. This kind
100 // of complication does not occur for positive type IDs because type infos are
101 // output using a fixed width encoding. FilterOffsets[i] holds the byte
102 // offset corresponding to FilterIds[i].
104 const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
105 SmallVector<int, 16> FilterOffsets;
106 FilterOffsets.reserve(FilterIds.size());
109 for (std::vector<unsigned>::const_iterator
110 I = FilterIds.begin(), E = FilterIds.end(); I != E; ++I) {
111 FilterOffsets.push_back(Offset);
112 Offset -= getULEB128Size(*I);
115 FirstActions.reserve(LandingPads.size());
118 unsigned SizeActions = 0;
119 const LandingPadInfo *PrevLPI = 0;
121 for (SmallVectorImpl<const LandingPadInfo *>::const_iterator
122 I = LandingPads.begin(), E = LandingPads.end(); I != E; ++I) {
123 const LandingPadInfo *LPI = *I;
124 const std::vector<int> &TypeIds = LPI->TypeIds;
125 unsigned NumShared = PrevLPI ? SharedTypeIds(LPI, PrevLPI) : 0;
126 unsigned SizeSiteActions = 0;
128 if (NumShared < TypeIds.size()) {
129 unsigned SizeAction = 0;
130 unsigned PrevAction = (unsigned)-1;
133 unsigned SizePrevIds = PrevLPI->TypeIds.size();
134 assert(Actions.size());
135 PrevAction = Actions.size() - 1;
136 SizeAction = getSLEB128Size(Actions[PrevAction].NextAction) +
137 getSLEB128Size(Actions[PrevAction].ValueForTypeID);
139 for (unsigned j = NumShared; j != SizePrevIds; ++j) {
140 assert(PrevAction != (unsigned)-1 && "PrevAction is invalid!");
141 SizeAction -= getSLEB128Size(Actions[PrevAction].ValueForTypeID);
142 SizeAction += -Actions[PrevAction].NextAction;
143 PrevAction = Actions[PrevAction].Previous;
147 // Compute the actions.
148 for (unsigned J = NumShared, M = TypeIds.size(); J != M; ++J) {
149 int TypeID = TypeIds[J];
150 assert(-1 - TypeID < (int)FilterOffsets.size() && "Unknown filter id!");
151 int ValueForTypeID = TypeID < 0 ? FilterOffsets[-1 - TypeID] : TypeID;
152 unsigned SizeTypeID = getSLEB128Size(ValueForTypeID);
154 int NextAction = SizeAction ? -(SizeAction + SizeTypeID) : 0;
155 SizeAction = SizeTypeID + getSLEB128Size(NextAction);
156 SizeSiteActions += SizeAction;
158 ActionEntry Action = { ValueForTypeID, NextAction, PrevAction };
159 Actions.push_back(Action);
160 PrevAction = Actions.size() - 1;
163 // Record the first action of the landing pad site.
164 FirstAction = SizeActions + SizeSiteActions - SizeAction + 1;
165 } // else identical - re-use previous FirstAction
167 // Information used when created the call-site table. The action record
168 // field of the call site record is the offset of the first associated
169 // action record, relative to the start of the actions table. This value is
170 // biased by 1 (1 indicating the start of the actions table), and 0
171 // indicates that there are no actions.
172 FirstActions.push_back(FirstAction);
174 // Compute this sites contribution to size.
175 SizeActions += SizeSiteActions;
183 /// CallToNoUnwindFunction - Return `true' if this is a call to a function
184 /// marked `nounwind'. Return `false' otherwise.
185 bool DwarfException::CallToNoUnwindFunction(const MachineInstr *MI) {
186 assert(MI->isCall() && "This should be a call instruction!");
188 bool MarkedNoUnwind = false;
189 bool SawFunc = false;
191 for (unsigned I = 0, E = MI->getNumOperands(); I != E; ++I) {
192 const MachineOperand &MO = MI->getOperand(I);
194 if (!MO.isGlobal()) continue;
196 const Function *F = dyn_cast<Function>(MO.getGlobal());
197 if (F == 0) continue;
200 // Be conservative. If we have more than one function operand for this
201 // call, then we can't make the assumption that it's the callee and
202 // not a parameter to the call.
204 // FIXME: Determine if there's a way to say that `F' is the callee or
206 MarkedNoUnwind = false;
210 MarkedNoUnwind = F->doesNotThrow();
214 return MarkedNoUnwind;
217 /// ComputeCallSiteTable - Compute the call-site table. The entry for an invoke
218 /// has a try-range containing the call, a non-zero landing pad, and an
219 /// appropriate action. The entry for an ordinary call has a try-range
220 /// containing the call and zero for the landing pad and the action. Calls
221 /// marked 'nounwind' have no entry and must not be contained in the try-range
222 /// of any entry - they form gaps in the table. Entries must be ordered by
223 /// try-range address.
224 void DwarfException::
225 ComputeCallSiteTable(SmallVectorImpl<CallSiteEntry> &CallSites,
226 const RangeMapType &PadMap,
227 const SmallVectorImpl<const LandingPadInfo *> &LandingPads,
228 const SmallVectorImpl<unsigned> &FirstActions) {
229 // The end label of the previous invoke or nounwind try-range.
230 MCSymbol *LastLabel = 0;
232 // Whether there is a potentially throwing instruction (currently this means
233 // an ordinary call) between the end of the previous try-range and now.
234 bool SawPotentiallyThrowing = false;
236 // Whether the last CallSite entry was for an invoke.
237 bool PreviousIsInvoke = false;
239 // Visit all instructions in order of address.
240 for (MachineFunction::const_iterator I = Asm->MF->begin(), E = Asm->MF->end();
242 for (MachineBasicBlock::const_iterator MI = I->begin(), E = I->end();
244 if (!MI->isLabel()) {
246 SawPotentiallyThrowing |= !CallToNoUnwindFunction(MI);
250 // End of the previous try-range?
251 MCSymbol *BeginLabel = MI->getOperand(0).getMCSymbol();
252 if (BeginLabel == LastLabel)
253 SawPotentiallyThrowing = false;
255 // Beginning of a new try-range?
256 RangeMapType::const_iterator L = PadMap.find(BeginLabel);
257 if (L == PadMap.end())
258 // Nope, it was just some random label.
261 const PadRange &P = L->second;
262 const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
263 assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
264 "Inconsistent landing pad map!");
266 // For Dwarf exception handling (SjLj handling doesn't use this). If some
267 // instruction between the previous try-range and this one may throw,
268 // create a call-site entry with no landing pad for the region between the
270 if (SawPotentiallyThrowing && Asm->MAI->isExceptionHandlingDwarf()) {
271 CallSiteEntry Site = { LastLabel, BeginLabel, 0, 0 };
272 CallSites.push_back(Site);
273 PreviousIsInvoke = false;
276 LastLabel = LandingPad->EndLabels[P.RangeIndex];
277 assert(BeginLabel && LastLabel && "Invalid landing pad!");
279 if (!LandingPad->LandingPadLabel) {
281 PreviousIsInvoke = false;
283 // This try-range is for an invoke.
284 CallSiteEntry Site = {
287 LandingPad->LandingPadLabel,
288 FirstActions[P.PadIndex]
291 // Try to merge with the previous call-site. SJLJ doesn't do this
292 if (PreviousIsInvoke && Asm->MAI->isExceptionHandlingDwarf()) {
293 CallSiteEntry &Prev = CallSites.back();
294 if (Site.PadLabel == Prev.PadLabel && Site.Action == Prev.Action) {
295 // Extend the range of the previous entry.
296 Prev.EndLabel = Site.EndLabel;
301 // Otherwise, create a new call-site.
302 if (Asm->MAI->isExceptionHandlingDwarf())
303 CallSites.push_back(Site);
305 // SjLj EH must maintain the call sites in the order assigned
306 // to them by the SjLjPrepare pass.
307 unsigned SiteNo = MMI->getCallSiteBeginLabel(BeginLabel);
308 if (CallSites.size() < SiteNo)
309 CallSites.resize(SiteNo);
310 CallSites[SiteNo - 1] = Site;
312 PreviousIsInvoke = true;
317 // If some instruction between the previous try-range and the end of the
318 // function may throw, create a call-site entry with no landing pad for the
319 // region following the try-range.
320 if (SawPotentiallyThrowing && Asm->MAI->isExceptionHandlingDwarf()) {
321 CallSiteEntry Site = { LastLabel, 0, 0, 0 };
322 CallSites.push_back(Site);
326 /// EmitExceptionTable - Emit landing pads and actions.
328 /// The general organization of the table is complex, but the basic concepts are
329 /// easy. First there is a header which describes the location and organization
330 /// of the three components that follow.
332 /// 1. The landing pad site information describes the range of code covered by
333 /// the try. In our case it's an accumulation of the ranges covered by the
334 /// invokes in the try. There is also a reference to the landing pad that
335 /// handles the exception once processed. Finally an index into the actions
337 /// 2. The action table, in our case, is composed of pairs of type IDs and next
338 /// action offset. Starting with the action index from the landing pad
339 /// site, each type ID is checked for a match to the current exception. If
340 /// it matches then the exception and type id are passed on to the landing
341 /// pad. Otherwise the next action is looked up. This chain is terminated
342 /// with a next action of zero. If no type id is found then the frame is
343 /// unwound and handling continues.
344 /// 3. Type ID table contains references to all the C++ typeinfo for all
345 /// catches in the function. This tables is reverse indexed base 1.
346 void DwarfException::EmitExceptionTable() {
347 const std::vector<const GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
348 const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
349 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
351 // Sort the landing pads in order of their type ids. This is used to fold
352 // duplicate actions.
353 SmallVector<const LandingPadInfo *, 64> LandingPads;
354 LandingPads.reserve(PadInfos.size());
356 for (unsigned i = 0, N = PadInfos.size(); i != N; ++i)
357 LandingPads.push_back(&PadInfos[i]);
359 std::sort(LandingPads.begin(), LandingPads.end(), PadLT);
361 // Compute the actions table and gather the first action index for each
363 SmallVector<ActionEntry, 32> Actions;
364 SmallVector<unsigned, 64> FirstActions;
365 unsigned SizeActions=ComputeActionsTable(LandingPads, Actions, FirstActions);
367 // Invokes and nounwind calls have entries in PadMap (due to being bracketed
368 // by try-range labels when lowered). Ordinary calls do not, so appropriate
369 // try-ranges for them need be deduced when using DWARF exception handling.
371 for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
372 const LandingPadInfo *LandingPad = LandingPads[i];
373 for (unsigned j = 0, E = LandingPad->BeginLabels.size(); j != E; ++j) {
374 MCSymbol *BeginLabel = LandingPad->BeginLabels[j];
375 assert(!PadMap.count(BeginLabel) && "Duplicate landing pad labels!");
376 PadRange P = { i, j };
377 PadMap[BeginLabel] = P;
381 // Compute the call-site table.
382 SmallVector<CallSiteEntry, 64> CallSites;
383 ComputeCallSiteTable(CallSites, PadMap, LandingPads, FirstActions);
388 bool IsSJLJ = Asm->MAI->getExceptionHandlingType() == ExceptionHandling::SjLj;
389 bool HaveTTData = IsSJLJ ? (!TypeInfos.empty() || !FilterIds.empty()) : true;
391 unsigned CallSiteTableLength;
393 CallSiteTableLength = 0;
395 unsigned SiteStartSize = 4; // dwarf::DW_EH_PE_udata4
396 unsigned SiteLengthSize = 4; // dwarf::DW_EH_PE_udata4
397 unsigned LandingPadSize = 4; // dwarf::DW_EH_PE_udata4
398 CallSiteTableLength =
399 CallSites.size() * (SiteStartSize + SiteLengthSize + LandingPadSize);
402 for (unsigned i = 0, e = CallSites.size(); i < e; ++i) {
403 CallSiteTableLength += getULEB128Size(CallSites[i].Action);
405 CallSiteTableLength += getULEB128Size(i);
409 const MCSection *LSDASection = Asm->getObjFileLowering().getLSDASection();
410 unsigned TTypeEncoding;
411 unsigned TypeFormatSize;
414 // For SjLj exceptions, if there is no TypeInfo, then we just explicitly say
415 // that we're omitting that bit.
416 TTypeEncoding = dwarf::DW_EH_PE_omit;
417 // dwarf::DW_EH_PE_absptr
418 TypeFormatSize = Asm->getDataLayout().getPointerSize();
420 // Okay, we have actual filters or typeinfos to emit. As such, we need to
421 // pick a type encoding for them. We're about to emit a list of pointers to
422 // typeinfo objects at the end of the LSDA. However, unless we're in static
423 // mode, this reference will require a relocation by the dynamic linker.
425 // Because of this, we have a couple of options:
427 // 1) If we are in -static mode, we can always use an absolute reference
428 // from the LSDA, because the static linker will resolve it.
430 // 2) Otherwise, if the LSDA section is writable, we can output the direct
431 // reference to the typeinfo and allow the dynamic linker to relocate
432 // it. Since it is in a writable section, the dynamic linker won't
435 // 3) Finally, if we're in PIC mode and the LDSA section isn't writable,
436 // we need to use some form of indirection. For example, on Darwin,
437 // we can output a statically-relocatable reference to a dyld stub. The
438 // offset to the stub is constant, but the contents are in a section
439 // that is updated by the dynamic linker. This is easy enough, but we
440 // need to tell the personality function of the unwinder to indirect
441 // through the dyld stub.
443 // FIXME: When (3) is actually implemented, we'll have to emit the stubs
444 // somewhere. This predicate should be moved to a shared location that is
445 // in target-independent code.
447 TTypeEncoding = Asm->getObjFileLowering().getTTypeEncoding();
448 TypeFormatSize = Asm->GetSizeOfEncodedValue(TTypeEncoding);
451 // Begin the exception table.
452 // Sometimes we want not to emit the data into separate section (e.g. ARM
453 // EHABI). In this case LSDASection will be NULL.
455 Asm->OutStreamer.SwitchSection(LSDASection);
456 Asm->EmitAlignment(2);
460 Asm->OutContext.GetOrCreateSymbol(Twine("GCC_except_table")+
461 Twine(Asm->getFunctionNumber()));
462 Asm->OutStreamer.EmitLabel(GCCETSym);
463 Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("exception",
464 Asm->getFunctionNumber()));
467 Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("_LSDA_",
468 Asm->getFunctionNumber()));
470 // Emit the LSDA header.
471 Asm->EmitEncodingByte(dwarf::DW_EH_PE_omit, "@LPStart");
472 Asm->EmitEncodingByte(TTypeEncoding, "@TType");
474 // The type infos need to be aligned. GCC does this by inserting padding just
475 // before the type infos. However, this changes the size of the exception
476 // table, so you need to take this into account when you output the exception
477 // table size. However, the size is output using a variable length encoding.
478 // So by increasing the size by inserting padding, you may increase the number
479 // of bytes used for writing the size. If it increases, say by one byte, then
480 // you now need to output one less byte of padding to get the type infos
481 // aligned. However this decreases the size of the exception table. This
482 // changes the value you have to output for the exception table size. Due to
483 // the variable length encoding, the number of bytes used for writing the
484 // length may decrease. If so, you then have to increase the amount of
485 // padding. And so on. If you look carefully at the GCC code you will see that
486 // it indeed does this in a loop, going on and on until the values stabilize.
487 // We chose another solution: don't output padding inside the table like GCC
488 // does, instead output it before the table.
489 unsigned SizeTypes = TypeInfos.size() * TypeFormatSize;
490 unsigned CallSiteTableLengthSize = getULEB128Size(CallSiteTableLength);
491 unsigned TTypeBaseOffset =
492 sizeof(int8_t) + // Call site format
493 CallSiteTableLengthSize + // Call site table length size
494 CallSiteTableLength + // Call site table length
495 SizeActions + // Actions size
497 unsigned TTypeBaseOffsetSize = getULEB128Size(TTypeBaseOffset);
499 sizeof(int8_t) + // LPStart format
500 sizeof(int8_t) + // TType format
501 (HaveTTData ? TTypeBaseOffsetSize : 0) + // TType base offset size
502 TTypeBaseOffset; // TType base offset
503 unsigned SizeAlign = (4 - TotalSize) & 3;
506 // Account for any extra padding that will be added to the call site table
508 Asm->EmitULEB128(TTypeBaseOffset, "@TType base offset", SizeAlign);
512 bool VerboseAsm = Asm->OutStreamer.isVerboseAsm();
514 // SjLj Exception handling
516 Asm->EmitEncodingByte(dwarf::DW_EH_PE_udata4, "Call site");
518 // Add extra padding if it wasn't added to the TType base offset.
519 Asm->EmitULEB128(CallSiteTableLength, "Call site table length", SizeAlign);
521 // Emit the landing pad site information.
523 for (SmallVectorImpl<CallSiteEntry>::const_iterator
524 I = CallSites.begin(), E = CallSites.end(); I != E; ++I, ++idx) {
525 const CallSiteEntry &S = *I;
527 // Offset of the landing pad, counted in 16-byte bundles relative to the
530 Asm->OutStreamer.AddComment(">> Call Site " + Twine(idx) + " <<");
531 Asm->OutStreamer.AddComment(" On exception at call site "+Twine(idx));
533 Asm->EmitULEB128(idx);
535 // Offset of the first associated action record, relative to the start of
536 // the action table. This value is biased by 1 (1 indicates the start of
537 // the action table), and 0 indicates that there are no actions.
540 Asm->OutStreamer.AddComment(" Action: cleanup");
542 Asm->OutStreamer.AddComment(" Action: " +
543 Twine((S.Action - 1) / 2 + 1));
545 Asm->EmitULEB128(S.Action);
548 // DWARF Exception handling
549 assert(Asm->MAI->isExceptionHandlingDwarf());
551 // The call-site table is a list of all call sites that may throw an
552 // exception (including C++ 'throw' statements) in the procedure
553 // fragment. It immediately follows the LSDA header. Each entry indicates,
554 // for a given call, the first corresponding action record and corresponding
557 // The table begins with the number of bytes, stored as an LEB128
558 // compressed, unsigned integer. The records immediately follow the record
559 // count. They are sorted in increasing call-site address. Each record
562 // * The position of the call-site.
563 // * The position of the landing pad.
564 // * The first action record for that call site.
566 // A missing entry in the call-site table indicates that a call is not
567 // supposed to throw.
569 // Emit the landing pad call site table.
570 Asm->EmitEncodingByte(dwarf::DW_EH_PE_udata4, "Call site");
572 // Add extra padding if it wasn't added to the TType base offset.
573 Asm->EmitULEB128(CallSiteTableLength, "Call site table length", SizeAlign);
576 for (SmallVectorImpl<CallSiteEntry>::const_iterator
577 I = CallSites.begin(), E = CallSites.end(); I != E; ++I) {
578 const CallSiteEntry &S = *I;
580 MCSymbol *EHFuncBeginSym =
581 Asm->GetTempSymbol("eh_func_begin", Asm->getFunctionNumber());
583 MCSymbol *BeginLabel = S.BeginLabel;
585 BeginLabel = EHFuncBeginSym;
586 MCSymbol *EndLabel = S.EndLabel;
588 EndLabel = Asm->GetTempSymbol("eh_func_end", Asm->getFunctionNumber());
591 // Offset of the call site relative to the previous call site, counted in
592 // number of 16-byte bundles. The first call site is counted relative to
593 // the start of the procedure fragment.
595 Asm->OutStreamer.AddComment(">> Call Site " + Twine(++Entry) + " <<");
596 Asm->EmitLabelDifference(BeginLabel, EHFuncBeginSym, 4);
598 Asm->OutStreamer.AddComment(Twine(" Call between ") +
599 BeginLabel->getName() + " and " +
600 EndLabel->getName());
601 Asm->EmitLabelDifference(EndLabel, BeginLabel, 4);
603 // Offset of the landing pad, counted in 16-byte bundles relative to the
607 Asm->OutStreamer.AddComment(" has no landing pad");
608 Asm->OutStreamer.EmitIntValue(0, 4/*size*/);
611 Asm->OutStreamer.AddComment(Twine(" jumps to ") +
612 S.PadLabel->getName());
613 Asm->EmitLabelDifference(S.PadLabel, EHFuncBeginSym, 4);
616 // Offset of the first associated action record, relative to the start of
617 // the action table. This value is biased by 1 (1 indicates the start of
618 // the action table), and 0 indicates that there are no actions.
621 Asm->OutStreamer.AddComment(" On action: cleanup");
623 Asm->OutStreamer.AddComment(" On action: " +
624 Twine((S.Action - 1) / 2 + 1));
626 Asm->EmitULEB128(S.Action);
630 // Emit the Action Table.
632 for (SmallVectorImpl<ActionEntry>::const_iterator
633 I = Actions.begin(), E = Actions.end(); I != E; ++I) {
634 const ActionEntry &Action = *I;
637 // Emit comments that decode the action table.
638 Asm->OutStreamer.AddComment(">> Action Record " + Twine(++Entry) + " <<");
643 // Used by the runtime to match the type of the thrown exception to the
644 // type of the catch clauses or the types in the exception specification.
646 if (Action.ValueForTypeID > 0)
647 Asm->OutStreamer.AddComment(" Catch TypeInfo " +
648 Twine(Action.ValueForTypeID));
649 else if (Action.ValueForTypeID < 0)
650 Asm->OutStreamer.AddComment(" Filter TypeInfo " +
651 Twine(Action.ValueForTypeID));
653 Asm->OutStreamer.AddComment(" Cleanup");
655 Asm->EmitSLEB128(Action.ValueForTypeID);
659 // Self-relative signed displacement in bytes of the next action record,
660 // or 0 if there is no next action record.
662 if (Action.NextAction == 0) {
663 Asm->OutStreamer.AddComment(" No further actions");
665 unsigned NextAction = Entry + (Action.NextAction + 1) / 2;
666 Asm->OutStreamer.AddComment(" Continue to action "+Twine(NextAction));
669 Asm->EmitSLEB128(Action.NextAction);
672 EmitTypeInfos(TTypeEncoding);
674 Asm->EmitAlignment(2);
677 void DwarfException::EmitTypeInfos(unsigned TTypeEncoding) {
678 const std::vector<const GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
679 const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
681 bool VerboseAsm = Asm->OutStreamer.isVerboseAsm();
684 // Emit the Catch TypeInfos.
685 if (VerboseAsm && !TypeInfos.empty()) {
686 Asm->OutStreamer.AddComment(">> Catch TypeInfos <<");
687 Asm->OutStreamer.AddBlankLine();
688 Entry = TypeInfos.size();
691 for (std::vector<const GlobalVariable *>::const_reverse_iterator
692 I = TypeInfos.rbegin(), E = TypeInfos.rend(); I != E; ++I) {
693 const GlobalVariable *GV = *I;
695 Asm->OutStreamer.AddComment("TypeInfo " + Twine(Entry--));
696 Asm->EmitTTypeReference(GV, TTypeEncoding);
699 // Emit the Exception Specifications.
700 if (VerboseAsm && !FilterIds.empty()) {
701 Asm->OutStreamer.AddComment(">> Filter TypeInfos <<");
702 Asm->OutStreamer.AddBlankLine();
705 for (std::vector<unsigned>::const_iterator
706 I = FilterIds.begin(), E = FilterIds.end(); I < E; ++I) {
707 unsigned TypeID = *I;
711 Asm->OutStreamer.AddComment("FilterInfo " + Twine(Entry));
714 Asm->EmitULEB128(TypeID);
718 /// endModule - Emit all exception information that should come after the
720 void DwarfException::endModule() {
721 llvm_unreachable("Should be implemented");
724 /// beginFunction - Gather pre-function exception information. Assumes it's
725 /// being emitted immediately after the function entry point.
726 void DwarfException::beginFunction(const MachineFunction *MF) {
727 llvm_unreachable("Should be implemented");
730 /// endFunction - Gather and emit post-function exception information.
731 void DwarfException::endFunction(const MachineFunction *) {
732 llvm_unreachable("Should be implemented");