Fix part 1 of pr4682. PICADD is a 16-bit instruction even in thumb2 mode.
[llvm/avr.git] / lib / CodeGen / AsmPrinter / DwarfException.cpp
blobfec1ad7557377b9e06408aae842bbf5e795db7b3
1 //===-- CodeGen/AsmPrinter/DwarfException.cpp - Dwarf Exception Impl ------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file contains support for writing dwarf exception info into asm files.
12 //===----------------------------------------------------------------------===//
14 #include "DwarfException.h"
15 #include "llvm/Module.h"
16 #include "llvm/CodeGen/MachineModuleInfo.h"
17 #include "llvm/CodeGen/MachineFrameInfo.h"
18 #include "llvm/CodeGen/MachineLocation.h"
19 #include "llvm/Support/Dwarf.h"
20 #include "llvm/Support/Timer.h"
21 #include "llvm/Support/raw_ostream.h"
22 #include "llvm/Target/TargetAsmInfo.h"
23 #include "llvm/Target/TargetData.h"
24 #include "llvm/Target/TargetFrameInfo.h"
25 #include "llvm/Target/TargetLoweringObjectFile.h"
26 #include "llvm/Target/TargetOptions.h"
27 #include "llvm/Target/TargetRegisterInfo.h"
28 #include "llvm/ADT/StringExtras.h"
29 using namespace llvm;
31 static TimerGroup &getDwarfTimerGroup() {
32 static TimerGroup DwarfTimerGroup("Dwarf Exception");
33 return DwarfTimerGroup;
36 DwarfException::DwarfException(raw_ostream &OS, AsmPrinter *A,
37 const TargetAsmInfo *T)
38 : Dwarf(OS, A, T, "eh"), shouldEmitTable(false), shouldEmitMoves(false),
39 shouldEmitTableModule(false), shouldEmitMovesModule(false),
40 ExceptionTimer(0) {
41 if (TimePassesIsEnabled)
42 ExceptionTimer = new Timer("Dwarf Exception Writer",
43 getDwarfTimerGroup());
46 DwarfException::~DwarfException() {
47 delete ExceptionTimer;
50 void DwarfException::EmitCommonEHFrame(const Function *Personality,
51 unsigned Index) {
52 // Size and sign of stack growth.
53 int stackGrowth =
54 Asm->TM.getFrameInfo()->getStackGrowthDirection() ==
55 TargetFrameInfo::StackGrowsUp ?
56 TD->getPointerSize() : -TD->getPointerSize();
58 // Begin eh frame section.
59 Asm->SwitchToSection(Asm->getObjFileLowering().getEHFrameSection());
61 if (TAI->is_EHSymbolPrivate())
62 O << TAI->getPrivateGlobalPrefix();
64 O << "EH_frame" << Index << ":\n";
65 EmitLabel("section_eh_frame", Index);
67 // Define base labels.
68 EmitLabel("eh_frame_common", Index);
70 // Define the eh frame length.
71 EmitDifference("eh_frame_common_end", Index,
72 "eh_frame_common_begin", Index, true);
73 Asm->EOL("Length of Common Information Entry");
75 // EH frame header.
76 EmitLabel("eh_frame_common_begin", Index);
77 Asm->EmitInt32((int)0);
78 Asm->EOL("CIE Identifier Tag");
79 Asm->EmitInt8(dwarf::DW_CIE_VERSION);
80 Asm->EOL("CIE Version");
82 // The personality presence indicates that language specific information will
83 // show up in the eh frame.
84 Asm->EmitString(Personality ? "zPLR" : "zR");
85 Asm->EOL("CIE Augmentation");
87 // Round out reader.
88 Asm->EmitULEB128Bytes(1);
89 Asm->EOL("CIE Code Alignment Factor");
90 Asm->EmitSLEB128Bytes(stackGrowth);
91 Asm->EOL("CIE Data Alignment Factor");
92 Asm->EmitInt8(RI->getDwarfRegNum(RI->getRARegister(), true));
93 Asm->EOL("CIE Return Address Column");
95 // If there is a personality, we need to indicate the functions location.
96 if (Personality) {
97 Asm->EmitULEB128Bytes(7);
98 Asm->EOL("Augmentation Size");
100 if (TAI->getNeedsIndirectEncoding()) {
101 Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4 |
102 dwarf::DW_EH_PE_indirect);
103 Asm->EOL("Personality (pcrel sdata4 indirect)");
104 } else {
105 Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
106 Asm->EOL("Personality (pcrel sdata4)");
109 PrintRelDirective(true);
110 O << TAI->getPersonalityPrefix();
111 Asm->EmitExternalGlobal((const GlobalVariable *)(Personality));
112 O << TAI->getPersonalitySuffix();
113 if (strcmp(TAI->getPersonalitySuffix(), "+4@GOTPCREL"))
114 O << "-" << TAI->getPCSymbol();
115 Asm->EOL("Personality");
117 Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
118 Asm->EOL("LSDA Encoding (pcrel sdata4)");
120 Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
121 Asm->EOL("FDE Encoding (pcrel sdata4)");
122 } else {
123 Asm->EmitULEB128Bytes(1);
124 Asm->EOL("Augmentation Size");
126 Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
127 Asm->EOL("FDE Encoding (pcrel sdata4)");
130 // Indicate locations of general callee saved registers in frame.
131 std::vector<MachineMove> Moves;
132 RI->getInitialFrameState(Moves);
133 EmitFrameMoves(NULL, 0, Moves, true);
135 // On Darwin the linker honors the alignment of eh_frame, which means it must
136 // be 8-byte on 64-bit targets to match what gcc does. Otherwise you get
137 // holes which confuse readers of eh_frame.
138 Asm->EmitAlignment(TD->getPointerSize() == sizeof(int32_t) ? 2 : 3,
139 0, 0, false);
140 EmitLabel("eh_frame_common_end", Index);
142 Asm->EOL();
145 /// EmitEHFrame - Emit function exception frame information.
147 void DwarfException::EmitEHFrame(const FunctionEHFrameInfo &EHFrameInfo) {
148 assert(!EHFrameInfo.function->hasAvailableExternallyLinkage() &&
149 "Should not emit 'available externally' functions at all");
151 const Function *TheFunc = EHFrameInfo.function;
153 Asm->SwitchToSection(Asm->getObjFileLowering().getEHFrameSection());
155 // Externally visible entry into the functions eh frame info. If the
156 // corresponding function is static, this should not be externally visible.
157 if (!TheFunc->hasLocalLinkage())
158 if (const char *GlobalEHDirective = TAI->getGlobalEHDirective())
159 O << GlobalEHDirective << EHFrameInfo.FnName << "\n";
161 // If corresponding function is weak definition, this should be too.
162 if (TheFunc->isWeakForLinker() && TAI->getWeakDefDirective())
163 O << TAI->getWeakDefDirective() << EHFrameInfo.FnName << "\n";
165 // If there are no calls then you can't unwind. This may mean we can omit the
166 // EH Frame, but some environments do not handle weak absolute symbols. If
167 // UnwindTablesMandatory is set we cannot do this optimization; the unwind
168 // info is to be available for non-EH uses.
169 if (!EHFrameInfo.hasCalls && !UnwindTablesMandatory &&
170 (!TheFunc->isWeakForLinker() ||
171 !TAI->getWeakDefDirective() ||
172 TAI->getSupportsWeakOmittedEHFrame())) {
173 O << EHFrameInfo.FnName << " = 0\n";
174 // This name has no connection to the function, so it might get
175 // dead-stripped when the function is not, erroneously. Prohibit
176 // dead-stripping unconditionally.
177 if (const char *UsedDirective = TAI->getUsedDirective())
178 O << UsedDirective << EHFrameInfo.FnName << "\n\n";
179 } else {
180 O << EHFrameInfo.FnName << ":\n";
182 // EH frame header.
183 EmitDifference("eh_frame_end", EHFrameInfo.Number,
184 "eh_frame_begin", EHFrameInfo.Number, true);
185 Asm->EOL("Length of Frame Information Entry");
187 EmitLabel("eh_frame_begin", EHFrameInfo.Number);
189 EmitSectionOffset("eh_frame_begin", "eh_frame_common",
190 EHFrameInfo.Number, EHFrameInfo.PersonalityIndex,
191 true, true, false);
193 Asm->EOL("FDE CIE offset");
195 EmitReference("eh_func_begin", EHFrameInfo.Number, true, true);
196 Asm->EOL("FDE initial location");
197 EmitDifference("eh_func_end", EHFrameInfo.Number,
198 "eh_func_begin", EHFrameInfo.Number, true);
199 Asm->EOL("FDE address range");
201 // If there is a personality and landing pads then point to the language
202 // specific data area in the exception table.
203 if (EHFrameInfo.PersonalityIndex) {
204 Asm->EmitULEB128Bytes(4);
205 Asm->EOL("Augmentation size");
207 if (EHFrameInfo.hasLandingPads)
208 EmitReference("exception", EHFrameInfo.Number, true, true);
209 else
210 Asm->EmitInt32((int)0);
211 Asm->EOL("Language Specific Data Area");
212 } else {
213 Asm->EmitULEB128Bytes(0);
214 Asm->EOL("Augmentation size");
217 // Indicate locations of function specific callee saved registers in frame.
218 EmitFrameMoves("eh_func_begin", EHFrameInfo.Number, EHFrameInfo.Moves,
219 true);
221 // On Darwin the linker honors the alignment of eh_frame, which means it
222 // must be 8-byte on 64-bit targets to match what gcc does. Otherwise you
223 // get holes which confuse readers of eh_frame.
224 Asm->EmitAlignment(TD->getPointerSize() == sizeof(int32_t) ? 2 : 3,
225 0, 0, false);
226 EmitLabel("eh_frame_end", EHFrameInfo.Number);
228 // If the function is marked used, this table should be also. We cannot
229 // make the mark unconditional in this case, since retaining the table also
230 // retains the function in this case, and there is code around that depends
231 // on unused functions (calling undefined externals) being dead-stripped to
232 // link correctly. Yes, there really is.
233 if (MMI->isUsedFunction(EHFrameInfo.function))
234 if (const char *UsedDirective = TAI->getUsedDirective())
235 O << UsedDirective << EHFrameInfo.FnName << "\n\n";
239 /// SharedTypeIds - How many leading type ids two landing pads have in common.
240 unsigned DwarfException::SharedTypeIds(const LandingPadInfo *L,
241 const LandingPadInfo *R) {
242 const std::vector<int> &LIds = L->TypeIds, &RIds = R->TypeIds;
243 unsigned LSize = LIds.size(), RSize = RIds.size();
244 unsigned MinSize = LSize < RSize ? LSize : RSize;
245 unsigned Count = 0;
247 for (; Count != MinSize; ++Count)
248 if (LIds[Count] != RIds[Count])
249 return Count;
251 return Count;
254 /// PadLT - Order landing pads lexicographically by type id.
255 bool DwarfException::PadLT(const LandingPadInfo *L, const LandingPadInfo *R) {
256 const std::vector<int> &LIds = L->TypeIds, &RIds = R->TypeIds;
257 unsigned LSize = LIds.size(), RSize = RIds.size();
258 unsigned MinSize = LSize < RSize ? LSize : RSize;
260 for (unsigned i = 0; i != MinSize; ++i)
261 if (LIds[i] != RIds[i])
262 return LIds[i] < RIds[i];
264 return LSize < RSize;
267 /// ComputeActionsTable - Compute the actions table and gather the first action
268 /// index for each landing pad site.
269 unsigned DwarfException::
270 ComputeActionsTable(const SmallVectorImpl<const LandingPadInfo*> &LandingPads,
271 SmallVectorImpl<ActionEntry> &Actions,
272 SmallVectorImpl<unsigned> &FirstActions) {
273 // Negative type IDs index into FilterIds. Positive type IDs index into
274 // TypeInfos. The value written for a positive type ID is just the type ID
275 // itself. For a negative type ID, however, the value written is the
276 // (negative) byte offset of the corresponding FilterIds entry. The byte
277 // offset is usually equal to the type ID (because the FilterIds entries are
278 // written using a variable width encoding, which outputs one byte per entry
279 // as long as the value written is not too large) but can differ. This kind
280 // of complication does not occur for positive type IDs because type infos are
281 // output using a fixed width encoding. FilterOffsets[i] holds the byte
282 // offset corresponding to FilterIds[i].
284 const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
285 SmallVector<int, 16> FilterOffsets;
286 FilterOffsets.reserve(FilterIds.size());
287 int Offset = -1;
289 for (std::vector<unsigned>::const_iterator
290 I = FilterIds.begin(), E = FilterIds.end(); I != E; ++I) {
291 FilterOffsets.push_back(Offset);
292 Offset -= TargetAsmInfo::getULEB128Size(*I);
295 FirstActions.reserve(LandingPads.size());
297 int FirstAction = 0;
298 unsigned SizeActions = 0;
299 const LandingPadInfo *PrevLPI = 0;
301 for (SmallVectorImpl<const LandingPadInfo *>::const_iterator
302 I = LandingPads.begin(), E = LandingPads.end(); I != E; ++I) {
303 const LandingPadInfo *LPI = *I;
304 const std::vector<int> &TypeIds = LPI->TypeIds;
305 const unsigned NumShared = PrevLPI ? SharedTypeIds(LPI, PrevLPI) : 0;
306 unsigned SizeSiteActions = 0;
308 if (NumShared < TypeIds.size()) {
309 unsigned SizeAction = 0;
310 ActionEntry *PrevAction = 0;
312 if (NumShared) {
313 const unsigned SizePrevIds = PrevLPI->TypeIds.size();
314 assert(Actions.size());
315 PrevAction = &Actions.back();
316 SizeAction = TargetAsmInfo::getSLEB128Size(PrevAction->NextAction) +
317 TargetAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
319 for (unsigned j = NumShared; j != SizePrevIds; ++j) {
320 SizeAction -=
321 TargetAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
322 SizeAction += -PrevAction->NextAction;
323 PrevAction = PrevAction->Previous;
327 // Compute the actions.
328 for (unsigned J = NumShared, M = TypeIds.size(); J != M; ++J) {
329 int TypeID = TypeIds[J];
330 assert(-1 - TypeID < (int)FilterOffsets.size() && "Unknown filter id!");
331 int ValueForTypeID = TypeID < 0 ? FilterOffsets[-1 - TypeID] : TypeID;
332 unsigned SizeTypeID = TargetAsmInfo::getSLEB128Size(ValueForTypeID);
334 int NextAction = SizeAction ? -(SizeAction + SizeTypeID) : 0;
335 SizeAction = SizeTypeID + TargetAsmInfo::getSLEB128Size(NextAction);
336 SizeSiteActions += SizeAction;
338 ActionEntry Action = {ValueForTypeID, NextAction, PrevAction};
339 Actions.push_back(Action);
340 PrevAction = &Actions.back();
343 // Record the first action of the landing pad site.
344 FirstAction = SizeActions + SizeSiteActions - SizeAction + 1;
345 } // else identical - re-use previous FirstAction
347 FirstActions.push_back(FirstAction);
349 // Compute this sites contribution to size.
350 SizeActions += SizeSiteActions;
352 PrevLPI = LPI;
355 return SizeActions;
358 /// ComputeCallSiteTable - Compute the call-site table. The entry for an invoke
359 /// has a try-range containing the call, a non-zero landing pad and an
360 /// appropriate action. The entry for an ordinary call has a try-range
361 /// containing the call and zero for the landing pad and the action. Calls
362 /// marked 'nounwind' have no entry and must not be contained in the try-range
363 /// of any entry - they form gaps in the table. Entries must be ordered by
364 /// try-range address.
365 void DwarfException::
366 ComputeCallSiteTable(SmallVectorImpl<CallSiteEntry> &CallSites,
367 const RangeMapType &PadMap,
368 const SmallVectorImpl<const LandingPadInfo *> &LandingPads,
369 const SmallVectorImpl<unsigned> &FirstActions) {
370 // The end label of the previous invoke or nounwind try-range.
371 unsigned LastLabel = 0;
373 // Whether there is a potentially throwing instruction (currently this means
374 // an ordinary call) between the end of the previous try-range and now.
375 bool SawPotentiallyThrowing = false;
377 // Whether the last CallSite entry was for an invoke.
378 bool PreviousIsInvoke = false;
380 // Visit all instructions in order of address.
381 for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
382 I != E; ++I) {
383 for (MachineBasicBlock::const_iterator MI = I->begin(), E = I->end();
384 MI != E; ++MI) {
385 if (!MI->isLabel()) {
386 SawPotentiallyThrowing |= MI->getDesc().isCall();
387 continue;
390 unsigned BeginLabel = MI->getOperand(0).getImm();
391 assert(BeginLabel && "Invalid label!");
393 // End of the previous try-range?
394 if (BeginLabel == LastLabel)
395 SawPotentiallyThrowing = false;
397 // Beginning of a new try-range?
398 RangeMapType::iterator L = PadMap.find(BeginLabel);
399 if (L == PadMap.end())
400 // Nope, it was just some random label.
401 continue;
403 PadRange P = L->second;
404 const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
405 assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
406 "Inconsistent landing pad map!");
408 // If some instruction between the previous try-range and this one may
409 // throw, create a call-site entry with no landing pad for the region
410 // between the try-ranges.
411 if (SawPotentiallyThrowing) {
412 CallSiteEntry Site = {LastLabel, BeginLabel, 0, 0};
413 CallSites.push_back(Site);
414 PreviousIsInvoke = false;
417 LastLabel = LandingPad->EndLabels[P.RangeIndex];
418 assert(BeginLabel && LastLabel && "Invalid landing pad!");
420 if (LandingPad->LandingPadLabel) {
421 // This try-range is for an invoke.
422 CallSiteEntry Site = {BeginLabel, LastLabel,
423 LandingPad->LandingPadLabel,
424 FirstActions[P.PadIndex]};
426 // Try to merge with the previous call-site.
427 if (PreviousIsInvoke) {
428 CallSiteEntry &Prev = CallSites.back();
429 if (Site.PadLabel == Prev.PadLabel && Site.Action == Prev.Action) {
430 // Extend the range of the previous entry.
431 Prev.EndLabel = Site.EndLabel;
432 continue;
436 // Otherwise, create a new call-site.
437 CallSites.push_back(Site);
438 PreviousIsInvoke = true;
439 } else {
440 // Create a gap.
441 PreviousIsInvoke = false;
446 // If some instruction between the previous try-range and the end of the
447 // function may throw, create a call-site entry with no landing pad for the
448 // region following the try-range.
449 if (SawPotentiallyThrowing) {
450 CallSiteEntry Site = {LastLabel, 0, 0, 0};
451 CallSites.push_back(Site);
455 /// EmitExceptionTable - Emit landing pads and actions.
457 /// The general organization of the table is complex, but the basic concepts are
458 /// easy. First there is a header which describes the location and organization
459 /// of the three components that follow.
460 ///
461 /// 1. The landing pad site information describes the range of code covered by
462 /// the try. In our case it's an accumulation of the ranges covered by the
463 /// invokes in the try. There is also a reference to the landing pad that
464 /// handles the exception once processed. Finally an index into the actions
465 /// table.
466 /// 2. The action table, in our case, is composed of pairs of type ids and next
467 /// action offset. Starting with the action index from the landing pad
468 /// site, each type Id is checked for a match to the current exception. If
469 /// it matches then the exception and type id are passed on to the landing
470 /// pad. Otherwise the next action is looked up. This chain is terminated
471 /// with a next action of zero. If no type id is found the the frame is
472 /// unwound and handling continues.
473 /// 3. Type id table contains references to all the C++ typeinfo for all
474 /// catches in the function. This tables is reversed indexed base 1.
475 void DwarfException::EmitExceptionTable() {
476 const std::vector<GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
477 const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
478 const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
479 if (PadInfos.empty()) return;
481 // Sort the landing pads in order of their type ids. This is used to fold
482 // duplicate actions.
483 SmallVector<const LandingPadInfo *, 64> LandingPads;
484 LandingPads.reserve(PadInfos.size());
486 for (unsigned i = 0, N = PadInfos.size(); i != N; ++i)
487 LandingPads.push_back(&PadInfos[i]);
489 std::sort(LandingPads.begin(), LandingPads.end(), PadLT);
491 // Compute the actions table and gather the first action index for each
492 // landing pad site.
493 SmallVector<ActionEntry, 32> Actions;
494 SmallVector<unsigned, 64> FirstActions;
495 unsigned SizeActions = ComputeActionsTable(LandingPads, Actions, FirstActions);
497 // Invokes and nounwind calls have entries in PadMap (due to being bracketed
498 // by try-range labels when lowered). Ordinary calls do not, so appropriate
499 // try-ranges for them need be deduced.
500 RangeMapType PadMap;
501 for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
502 const LandingPadInfo *LandingPad = LandingPads[i];
503 for (unsigned j = 0, E = LandingPad->BeginLabels.size(); j != E; ++j) {
504 unsigned BeginLabel = LandingPad->BeginLabels[j];
505 assert(!PadMap.count(BeginLabel) && "Duplicate landing pad labels!");
506 PadRange P = { i, j };
507 PadMap[BeginLabel] = P;
511 // Compute the call-site table.
512 SmallVector<CallSiteEntry, 64> CallSites;
513 ComputeCallSiteTable(CallSites, PadMap, LandingPads, FirstActions);
515 // Final tallies.
517 // Call sites.
518 const unsigned SiteStartSize = sizeof(int32_t); // DW_EH_PE_udata4
519 const unsigned SiteLengthSize = sizeof(int32_t); // DW_EH_PE_udata4
520 const unsigned LandingPadSize = sizeof(int32_t); // DW_EH_PE_udata4
521 unsigned SizeSites = CallSites.size() * (SiteStartSize +
522 SiteLengthSize +
523 LandingPadSize);
524 for (unsigned i = 0, e = CallSites.size(); i < e; ++i)
525 SizeSites += TargetAsmInfo::getULEB128Size(CallSites[i].Action);
527 // Type infos.
528 const unsigned TypeInfoSize = TD->getPointerSize(); // DW_EH_PE_absptr
529 unsigned SizeTypes = TypeInfos.size() * TypeInfoSize;
531 unsigned TypeOffset = sizeof(int8_t) + // Call site format
532 TargetAsmInfo::getULEB128Size(SizeSites) + // Call-site table length
533 SizeSites + SizeActions + SizeTypes;
535 unsigned TotalSize = sizeof(int8_t) + // LPStart format
536 sizeof(int8_t) + // TType format
537 TargetAsmInfo::getULEB128Size(TypeOffset) + // TType base offset
538 TypeOffset;
540 unsigned SizeAlign = (4 - TotalSize) & 3;
542 // Begin the exception table.
543 const MCSection *LSDASection = Asm->getObjFileLowering().getLSDASection();
544 Asm->SwitchToSection(LSDASection);
545 Asm->EmitAlignment(2, 0, 0, false);
546 O << "GCC_except_table" << SubprogramCount << ":\n";
548 for (unsigned i = 0; i != SizeAlign; ++i) {
549 Asm->EmitInt8(0);
550 Asm->EOL("Padding");
553 EmitLabel("exception", SubprogramCount);
555 // Emit the header.
556 Asm->EmitInt8(dwarf::DW_EH_PE_omit);
557 Asm->EOL("LPStart format (DW_EH_PE_omit)");
559 #if 0
560 if (TypeInfos.empty() && FilterIds.empty()) {
561 // If there are no typeinfos or filters, there is nothing to emit, optimize
562 // by specifying the "omit" encoding.
563 Asm->EmitInt8(dwarf::DW_EH_PE_omit);
564 Asm->EOL("TType format (DW_EH_PE_omit)");
565 } else {
566 // Okay, we have actual filters or typeinfos to emit. As such, we need to
567 // pick a type encoding for them. We're about to emit a list of pointers to
568 // typeinfo objects at the end of the LSDA. However, unless we're in static
569 // mode, this reference will require a relocation by the dynamic linker.
571 // Because of this, we have a couple of options:
572 // 1) If we are in -static mode, we can always use an absolute reference
573 // from the LSDA, because the static linker will resolve it.
574 // 2) Otherwise, if the LSDA section is writable, we can output the direct
575 // reference to the typeinfo and allow the dynamic linker to relocate
576 // it. Since it is in a writable section, the dynamic linker won't
577 // have a problem.
578 // 3) Finally, if we're in PIC mode and the LDSA section isn't writable,
579 // we need to use some form of indirection. For example, on Darwin,
580 // we can output a statically-relocatable reference to a dyld stub. The
581 // offset to the stub is constant, but the contents are in a section
582 // that is updated by the dynamic linker. This is easy enough, but we
583 // need to tell the personality function of the unwinder to indirect
584 // through the dyld stub.
586 // FIXME: When this is actually implemented, we'll have to emit the stubs
587 // somewhere. This predicate should be moved to a shared location that is
588 // in target-independent code.
590 if (LSDASection->isWritable() ||
591 Asm->TM.getRelocationModel() == Reloc::Static) {
592 Asm->EmitInt8(DW_EH_PE_absptr);
593 Asm->EOL("TType format (DW_EH_PE_absptr)");
594 } else {
595 Asm->EmitInt8(DW_EH_PE_pcrel | DW_EH_PE_indirect | DW_EH_PE_sdata4);
596 Asm->EOL("TType format (DW_EH_PE_pcrel | DW_EH_PE_indirect"
597 " | DW_EH_PE_sdata4)");
599 Asm->EmitULEB128Bytes(TypeOffset);
600 Asm->EOL("TType base offset");
602 #else
603 Asm->EmitInt8(dwarf::DW_EH_PE_absptr);
604 Asm->EOL("TType format (DW_EH_PE_absptr)");
605 Asm->EmitULEB128Bytes(TypeOffset);
606 Asm->EOL("TType base offset");
607 #endif
609 Asm->EmitInt8(dwarf::DW_EH_PE_udata4);
610 Asm->EOL("Call site format (DW_EH_PE_udata4)");
611 Asm->EmitULEB128Bytes(SizeSites);
612 Asm->EOL("Call-site table length");
614 // Emit the landing pad site information.
615 for (SmallVectorImpl<CallSiteEntry>::const_iterator
616 I = CallSites.begin(), E = CallSites.end(); I != E; ++I) {
617 const CallSiteEntry &S = *I;
618 const char *BeginTag;
619 unsigned BeginNumber;
621 if (!S.BeginLabel) {
622 BeginTag = "eh_func_begin";
623 BeginNumber = SubprogramCount;
624 } else {
625 BeginTag = "label";
626 BeginNumber = S.BeginLabel;
629 EmitSectionOffset(BeginTag, "eh_func_begin", BeginNumber, SubprogramCount,
630 true, true);
631 Asm->EOL("Region start");
633 if (!S.EndLabel)
634 EmitDifference("eh_func_end", SubprogramCount, BeginTag, BeginNumber,
635 true);
636 else
637 EmitDifference("label", S.EndLabel, BeginTag, BeginNumber, true);
639 Asm->EOL("Region length");
641 if (!S.PadLabel)
642 Asm->EmitInt32(0);
643 else
644 EmitSectionOffset("label", "eh_func_begin", S.PadLabel, SubprogramCount,
645 true, true);
647 Asm->EOL("Landing pad");
649 Asm->EmitULEB128Bytes(S.Action);
650 Asm->EOL("Action");
653 // Emit the actions.
654 for (SmallVectorImpl<ActionEntry>::const_iterator
655 I = Actions.begin(), E = Actions.end(); I != E; ++I) {
656 const ActionEntry &Action = *I;
657 Asm->EmitSLEB128Bytes(Action.ValueForTypeID);
658 Asm->EOL("TypeInfo index");
659 Asm->EmitSLEB128Bytes(Action.NextAction);
660 Asm->EOL("Next action");
663 // Emit the type ids.
664 for (std::vector<GlobalVariable *>::const_reverse_iterator
665 I = TypeInfos.rbegin(), E = TypeInfos.rend(); I != E; ++I) {
666 GlobalVariable *GV = *I;
667 PrintRelDirective();
669 if (GV) {
670 std::string GLN;
671 O << Asm->getGlobalLinkName(GV, GLN);
672 } else {
673 O << "0";
676 Asm->EOL("TypeInfo");
679 // Emit the filter typeids.
680 for (std::vector<unsigned>::const_iterator
681 I = FilterIds.begin(), E = FilterIds.end(); I < E; ++I) {
682 unsigned TypeID = *I;
683 Asm->EmitULEB128Bytes(TypeID);
684 Asm->EOL("Filter TypeInfo index");
687 Asm->EmitAlignment(2, 0, 0, false);
690 /// EndModule - Emit all exception information that should come after the
691 /// content.
692 void DwarfException::EndModule() {
693 if (TimePassesIsEnabled)
694 ExceptionTimer->startTimer();
696 if (shouldEmitMovesModule || shouldEmitTableModule) {
697 const std::vector<Function *> Personalities = MMI->getPersonalities();
698 for (unsigned i = 0; i < Personalities.size(); ++i)
699 EmitCommonEHFrame(Personalities[i], i);
701 for (std::vector<FunctionEHFrameInfo>::iterator I = EHFrames.begin(),
702 E = EHFrames.end(); I != E; ++I)
703 EmitEHFrame(*I);
706 if (TimePassesIsEnabled)
707 ExceptionTimer->stopTimer();
710 /// BeginFunction - Gather pre-function exception information. Assumes being
711 /// emitted immediately after the function entry point.
712 void DwarfException::BeginFunction(MachineFunction *MF) {
713 if (TimePassesIsEnabled)
714 ExceptionTimer->startTimer();
716 this->MF = MF;
717 shouldEmitTable = shouldEmitMoves = false;
719 if (MMI && TAI->doesSupportExceptionHandling()) {
720 // Map all labels and get rid of any dead landing pads.
721 MMI->TidyLandingPads();
723 // If any landing pads survive, we need an EH table.
724 if (MMI->getLandingPads().size())
725 shouldEmitTable = true;
727 // See if we need frame move info.
728 if (!MF->getFunction()->doesNotThrow() || UnwindTablesMandatory)
729 shouldEmitMoves = true;
731 if (shouldEmitMoves || shouldEmitTable)
732 // Assumes in correct section after the entry point.
733 EmitLabel("eh_func_begin", ++SubprogramCount);
736 shouldEmitTableModule |= shouldEmitTable;
737 shouldEmitMovesModule |= shouldEmitMoves;
739 if (TimePassesIsEnabled)
740 ExceptionTimer->stopTimer();
743 /// EndFunction - Gather and emit post-function exception information.
745 void DwarfException::EndFunction() {
746 if (TimePassesIsEnabled)
747 ExceptionTimer->startTimer();
749 if (shouldEmitMoves || shouldEmitTable) {
750 EmitLabel("eh_func_end", SubprogramCount);
751 EmitExceptionTable();
753 // Save EH frame information
754 EHFrames.push_back(
755 FunctionEHFrameInfo(getAsm()->getCurrentFunctionEHName(MF),
756 SubprogramCount,
757 MMI->getPersonalityIndex(),
758 MF->getFrameInfo()->hasCalls(),
759 !MMI->getLandingPads().empty(),
760 MMI->getFrameMoves(),
761 MF->getFunction()));
764 if (TimePassesIsEnabled)
765 ExceptionTimer->stopTimer();