lib/ExecutionEngine/JIT/JITDwarfEmitter.cpp

   1 //===----- JITDwarfEmitter.cpp - Write dwarf tables into memory -----------===//
   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 defines a JITDwarfEmitter object that is used by the JIT to
  11 // write dwarf tables to memory.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "JIT.h"
  16 #include "JITDwarfEmitter.h"
  17 #include "llvm/Function.h"
  18 #include "llvm/ADT/DenseMap.h"
  19 #include "llvm/CodeGen/JITCodeEmitter.h"
  20 #include "llvm/CodeGen/MachineFunction.h"
  21 #include "llvm/CodeGen/MachineLocation.h"
  22 #include "llvm/CodeGen/MachineModuleInfo.h"
  23 #include "llvm/ExecutionEngine/JITMemoryManager.h"
  24 #include "llvm/Support/ErrorHandling.h"
  25 #include "llvm/MC/MCAsmInfo.h"
  26 #include "llvm/MC/MCSymbol.h"
  27 #include "llvm/Target/TargetData.h"
  28 #include "llvm/Target/TargetInstrInfo.h"
  29 #include "llvm/Target/TargetFrameInfo.h"
  30 #include "llvm/Target/TargetMachine.h"
  31 #include "llvm/Target/TargetRegisterInfo.h"
  32 using namespace llvm;
  33
  34 JITDwarfEmitter::JITDwarfEmitter(JIT& theJit) : MMI(0), Jit(theJit) {}
  35
  36
  37 unsigned char* JITDwarfEmitter::EmitDwarfTable(MachineFunction& F,
  38                                                JITCodeEmitter& jce,
  39                                                unsigned char* StartFunction,
  40                                                unsigned char* EndFunction,
  41                                                unsigned char* &EHFramePtr) {
  42   assert(MMI && "MachineModuleInfo not registered!");
  43
  44   const TargetMachine& TM = F.getTarget();
  45   TD = TM.getTargetData();
  46   stackGrowthDirection = TM.getFrameInfo()->getStackGrowthDirection();
  47   RI = TM.getRegisterInfo();
  48   JCE = &jce;
  49
  50   unsigned char* ExceptionTable = EmitExceptionTable(&F, StartFunction,
  51                                                      EndFunction);
  52
  53   unsigned char* Result = 0;
  54
  55   const std::vector<const Function *> Personalities = MMI->getPersonalities();
  56   EHFramePtr = EmitCommonEHFrame(Personalities[MMI->getPersonalityIndex()]);
  57
  58   Result = EmitEHFrame(Personalities[MMI->getPersonalityIndex()], EHFramePtr,
  59                        StartFunction, EndFunction, ExceptionTable);
  60
  61   return Result;
  62 }
  63
  64
  65 void
  66 JITDwarfEmitter::EmitFrameMoves(intptr_t BaseLabelPtr,
  67                                 const std::vector<MachineMove> &Moves) const {
  68   unsigned PointerSize = TD->getPointerSize();
  69   int stackGrowth = stackGrowthDirection == TargetFrameInfo::StackGrowsUp ?
  70           PointerSize : -PointerSize;
  71   MCSymbol *BaseLabel = 0;
  72
  73   for (unsigned i = 0, N = Moves.size(); i < N; ++i) {
  74     const MachineMove &Move = Moves[i];
  75     MCSymbol *Label = Move.getLabel();
  76
  77     // Throw out move if the label is invalid.
  78     if (Label && (*JCE->getLabelLocations())[Label] == 0)
  79       continue;
  80
  81     intptr_t LabelPtr = 0;
  82     if (Label) LabelPtr = JCE->getLabelAddress(Label);
  83
  84     const MachineLocation &Dst = Move.getDestination();
  85     const MachineLocation &Src = Move.getSource();
  86
  87     // Advance row if new location.
  88     if (BaseLabelPtr && Label && BaseLabel != Label) {
  89       JCE->emitByte(dwarf::DW_CFA_advance_loc4);
  90       JCE->emitInt32(LabelPtr - BaseLabelPtr);
  91
  92       BaseLabel = Label;
  93       BaseLabelPtr = LabelPtr;
  94     }
  95
  96     // If advancing cfa.
  97     if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
  98       if (!Src.isReg()) {
  99         if (Src.getReg() == MachineLocation::VirtualFP) {
 100           JCE->emitByte(dwarf::DW_CFA_def_cfa_offset);
 101         } else {
 102           JCE->emitByte(dwarf::DW_CFA_def_cfa);
 103           JCE->emitULEB128Bytes(RI->getDwarfRegNum(Src.getReg(), true));
 104         }
 105
 106         JCE->emitULEB128Bytes(-Src.getOffset());
 107       } else {
 108         llvm_unreachable("Machine move not supported yet.");
 109       }
 110     } else if (Src.isReg() &&
 111       Src.getReg() == MachineLocation::VirtualFP) {
 112       if (Dst.isReg()) {
 113         JCE->emitByte(dwarf::DW_CFA_def_cfa_register);
 114         JCE->emitULEB128Bytes(RI->getDwarfRegNum(Dst.getReg(), true));
 115       } else {
 116         llvm_unreachable("Machine move not supported yet.");
 117       }
 118     } else {
 119       unsigned Reg = RI->getDwarfRegNum(Src.getReg(), true);
 120       int Offset = Dst.getOffset() / stackGrowth;
 121
 122       if (Offset < 0) {
 123         JCE->emitByte(dwarf::DW_CFA_offset_extended_sf);
 124         JCE->emitULEB128Bytes(Reg);
 125         JCE->emitSLEB128Bytes(Offset);
 126       } else if (Reg < 64) {
 127         JCE->emitByte(dwarf::DW_CFA_offset + Reg);
 128         JCE->emitULEB128Bytes(Offset);
 129       } else {
 130         JCE->emitByte(dwarf::DW_CFA_offset_extended);
 131         JCE->emitULEB128Bytes(Reg);
 132         JCE->emitULEB128Bytes(Offset);
 133       }
 134     }
 135   }
 136 }
 137
 138 /// SharedTypeIds - How many leading type ids two landing pads have in common.
 139 static unsigned SharedTypeIds(const LandingPadInfo *L,
 140                               const LandingPadInfo *R) {
 141   const std::vector<int> &LIds = L->TypeIds, &RIds = R->TypeIds;
 142   unsigned LSize = LIds.size(), RSize = RIds.size();
 143   unsigned MinSize = LSize < RSize ? LSize : RSize;
 144   unsigned Count = 0;
 145
 146   for (; Count != MinSize; ++Count)
 147     if (LIds[Count] != RIds[Count])
 148       return Count;
 149
 150   return Count;
 151 }
 152
 153
 154 /// PadLT - Order landing pads lexicographically by type id.
 155 static bool PadLT(const LandingPadInfo *L, const LandingPadInfo *R) {
 156   const std::vector<int> &LIds = L->TypeIds, &RIds = R->TypeIds;
 157   unsigned LSize = LIds.size(), RSize = RIds.size();
 158   unsigned MinSize = LSize < RSize ? LSize : RSize;
 159
 160   for (unsigned i = 0; i != MinSize; ++i)
 161     if (LIds[i] != RIds[i])
 162       return LIds[i] < RIds[i];
 163
 164   return LSize < RSize;
 165 }
 166
 167 namespace {
 168
 169 /// ActionEntry - Structure describing an entry in the actions table.
 170 struct ActionEntry {
 171   int ValueForTypeID; // The value to write - may not be equal to the type id.
 172   int NextAction;
 173   struct ActionEntry *Previous;
 174 };
 175
 176 /// PadRange - Structure holding a try-range and the associated landing pad.
 177 struct PadRange {
 178   // The index of the landing pad.
 179   unsigned PadIndex;
 180   // The index of the begin and end labels in the landing pad's label lists.
 181   unsigned RangeIndex;
 182 };
 183
 184 typedef DenseMap<MCSymbol*, PadRange> RangeMapType;
 185
 186 /// CallSiteEntry - Structure describing an entry in the call-site table.
 187 struct CallSiteEntry {
 188   MCSymbol *BeginLabel; // zero indicates the start of the function.
 189   MCSymbol *EndLabel;   // zero indicates the end of the function.
 190   MCSymbol *PadLabel;   // zero indicates that there is no landing pad.
 191   unsigned Action;
 192 };
 193
 194 }
 195
 196 unsigned char* JITDwarfEmitter::EmitExceptionTable(MachineFunction* MF,
 197                                          unsigned char* StartFunction,
 198                                          unsigned char* EndFunction) const {
 199   assert(MMI && "MachineModuleInfo not registered!");
 200
 201   // Map all labels and get rid of any dead landing pads.
 202   MMI->TidyLandingPads(JCE->getLabelLocations());
 203
 204   const std::vector<const GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
 205   const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
 206   const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
 207   if (PadInfos.empty()) return 0;
 208
 209   // Sort the landing pads in order of their type ids.  This is used to fold
 210   // duplicate actions.
 211   SmallVector<const LandingPadInfo *, 64> LandingPads;
 212   LandingPads.reserve(PadInfos.size());
 213   for (unsigned i = 0, N = PadInfos.size(); i != N; ++i)
 214     LandingPads.push_back(&PadInfos[i]);
 215   std::sort(LandingPads.begin(), LandingPads.end(), PadLT);
 216
 217   // Negative type ids index into FilterIds, positive type ids index into
 218   // TypeInfos.  The value written for a positive type id is just the type
 219   // id itself.  For a negative type id, however, the value written is the
 220   // (negative) byte offset of the corresponding FilterIds entry.  The byte
 221   // offset is usually equal to the type id, because the FilterIds entries
 222   // are written using a variable width encoding which outputs one byte per
 223   // entry as long as the value written is not too large, but can differ.
 224   // This kind of complication does not occur for positive type ids because
 225   // type infos are output using a fixed width encoding.
 226   // FilterOffsets[i] holds the byte offset corresponding to FilterIds[i].
 227   SmallVector<int, 16> FilterOffsets;
 228   FilterOffsets.reserve(FilterIds.size());
 229   int Offset = -1;
 230   for(std::vector<unsigned>::const_iterator I = FilterIds.begin(),
 231     E = FilterIds.end(); I != E; ++I) {
 232     FilterOffsets.push_back(Offset);
 233     Offset -= MCAsmInfo::getULEB128Size(*I);
 234   }
 235
 236   // Compute the actions table and gather the first action index for each
 237   // landing pad site.
 238   SmallVector<ActionEntry, 32> Actions;
 239   SmallVector<unsigned, 64> FirstActions;
 240   FirstActions.reserve(LandingPads.size());
 241
 242   int FirstAction = 0;
 243   unsigned SizeActions = 0;
 244   for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
 245     const LandingPadInfo *LP = LandingPads[i];
 246     const std::vector<int> &TypeIds = LP->TypeIds;
 247     const unsigned NumShared = i ? SharedTypeIds(LP, LandingPads[i-1]) : 0;
 248     unsigned SizeSiteActions = 0;
 249
 250     if (NumShared < TypeIds.size()) {
 251       unsigned SizeAction = 0;
 252       ActionEntry *PrevAction = 0;
 253
 254       if (NumShared) {
 255         const unsigned SizePrevIds = LandingPads[i-1]->TypeIds.size();
 256         assert(Actions.size());
 257         PrevAction = &Actions.back();
 258         SizeAction = MCAsmInfo::getSLEB128Size(PrevAction->NextAction) +
 259           MCAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
 260         for (unsigned j = NumShared; j != SizePrevIds; ++j) {
 261           SizeAction -= MCAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
 262           SizeAction += -PrevAction->NextAction;
 263           PrevAction = PrevAction->Previous;
 264         }
 265       }
 266
 267       // Compute the actions.
 268       for (unsigned I = NumShared, M = TypeIds.size(); I != M; ++I) {
 269         int TypeID = TypeIds[I];
 270         assert(-1-TypeID < (int)FilterOffsets.size() && "Unknown filter id!");
 271         int ValueForTypeID = TypeID < 0 ? FilterOffsets[-1 - TypeID] : TypeID;
 272         unsigned SizeTypeID = MCAsmInfo::getSLEB128Size(ValueForTypeID);
 273
 274         int NextAction = SizeAction ? -(SizeAction + SizeTypeID) : 0;
 275         SizeAction = SizeTypeID + MCAsmInfo::getSLEB128Size(NextAction);
 276         SizeSiteActions += SizeAction;
 277
 278         ActionEntry Action = {ValueForTypeID, NextAction, PrevAction};
 279         Actions.push_back(Action);
 280
 281         PrevAction = &Actions.back();
 282       }
 283
 284       // Record the first action of the landing pad site.
 285       FirstAction = SizeActions + SizeSiteActions - SizeAction + 1;
 286     } // else identical - re-use previous FirstAction
 287
 288     FirstActions.push_back(FirstAction);
 289
 290     // Compute this sites contribution to size.
 291     SizeActions += SizeSiteActions;
 292   }
 293
 294   // Compute the call-site table.  Entries must be ordered by address.
 295   SmallVector<CallSiteEntry, 64> CallSites;
 296
 297   RangeMapType PadMap;
 298   for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
 299     const LandingPadInfo *LandingPad = LandingPads[i];
 300     for (unsigned j=0, E = LandingPad->BeginLabels.size(); j != E; ++j) {
 301       MCSymbol *BeginLabel = LandingPad->BeginLabels[j];
 302       assert(!PadMap.count(BeginLabel) && "Duplicate landing pad labels!");
 303       PadRange P = { i, j };
 304       PadMap[BeginLabel] = P;
 305     }
 306   }
 307
 308   bool MayThrow = false;
 309   MCSymbol *LastLabel = 0;
 310   for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
 311         I != E; ++I) {
 312     for (MachineBasicBlock::const_iterator MI = I->begin(), E = I->end();
 313           MI != E; ++MI) {
 314       if (!MI->isLabel()) {
 315         MayThrow |= MI->getDesc().isCall();
 316         continue;
 317       }
 318
 319       MCSymbol *BeginLabel = MI->getOperand(0).getMCSymbol();
 320       assert(BeginLabel && "Invalid label!");
 321
 322       if (BeginLabel == LastLabel)
 323         MayThrow = false;
 324
 325       RangeMapType::iterator L = PadMap.find(BeginLabel);
 326
 327       if (L == PadMap.end())
 328         continue;
 329
 330       PadRange P = L->second;
 331       const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
 332
 333       assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
 334               "Inconsistent landing pad map!");
 335
 336       // If some instruction between the previous try-range and this one may
 337       // throw, create a call-site entry with no landing pad for the region
 338       // between the try-ranges.
 339       if (MayThrow) {
 340         CallSiteEntry Site = {LastLabel, BeginLabel, 0, 0};
 341         CallSites.push_back(Site);
 342       }
 343
 344       LastLabel = LandingPad->EndLabels[P.RangeIndex];
 345       CallSiteEntry Site = {BeginLabel, LastLabel,
 346         LandingPad->LandingPadLabel, FirstActions[P.PadIndex]};
 347
 348       assert(Site.BeginLabel && Site.EndLabel && Site.PadLabel &&
 349               "Invalid landing pad!");
 350
 351       // Try to merge with the previous call-site.
 352       if (CallSites.size()) {
 353         CallSiteEntry &Prev = CallSites.back();
 354         if (Site.PadLabel == Prev.PadLabel && Site.Action == Prev.Action) {
 355           // Extend the range of the previous entry.
 356           Prev.EndLabel = Site.EndLabel;
 357           continue;
 358         }
 359       }
 360
 361       // Otherwise, create a new call-site.
 362       CallSites.push_back(Site);
 363     }
 364   }
 365   // If some instruction between the previous try-range and the end of the
 366   // function may throw, create a call-site entry with no landing pad for the
 367   // region following the try-range.
 368   if (MayThrow) {
 369     CallSiteEntry Site = {LastLabel, 0, 0, 0};
 370     CallSites.push_back(Site);
 371   }
 372
 373   // Final tallies.
 374   unsigned SizeSites = CallSites.size() * (sizeof(int32_t) + // Site start.
 375                                             sizeof(int32_t) + // Site length.
 376                                             sizeof(int32_t)); // Landing pad.
 377   for (unsigned i = 0, e = CallSites.size(); i < e; ++i)
 378     SizeSites += MCAsmInfo::getULEB128Size(CallSites[i].Action);
 379
 380   unsigned SizeTypes = TypeInfos.size() * TD->getPointerSize();
 381
 382   unsigned TypeOffset = sizeof(int8_t) + // Call site format
 383                         // Call-site table length
 384                         MCAsmInfo::getULEB128Size(SizeSites) +
 385                         SizeSites + SizeActions + SizeTypes;
 386
 387   // Begin the exception table.
 388   JCE->emitAlignmentWithFill(4, 0);
 389   // Asm->EOL("Padding");
 390
 391   unsigned char* DwarfExceptionTable = (unsigned char*)JCE->getCurrentPCValue();
 392
 393   // Emit the header.
 394   JCE->emitByte(dwarf::DW_EH_PE_omit);
 395   // Asm->EOL("LPStart format (DW_EH_PE_omit)");
 396   JCE->emitByte(dwarf::DW_EH_PE_absptr);
 397   // Asm->EOL("TType format (DW_EH_PE_absptr)");
 398   JCE->emitULEB128Bytes(TypeOffset);
 399   // Asm->EOL("TType base offset");
 400   JCE->emitByte(dwarf::DW_EH_PE_udata4);
 401   // Asm->EOL("Call site format (DW_EH_PE_udata4)");
 402   JCE->emitULEB128Bytes(SizeSites);
 403   // Asm->EOL("Call-site table length");
 404
 405   // Emit the landing pad site information.
 406   for (unsigned i = 0; i < CallSites.size(); ++i) {
 407     CallSiteEntry &S = CallSites[i];
 408     intptr_t BeginLabelPtr = 0;
 409     intptr_t EndLabelPtr = 0;
 410
 411     if (!S.BeginLabel) {
 412       BeginLabelPtr = (intptr_t)StartFunction;
 413       JCE->emitInt32(0);
 414     } else {
 415       BeginLabelPtr = JCE->getLabelAddress(S.BeginLabel);
 416       JCE->emitInt32(BeginLabelPtr - (intptr_t)StartFunction);
 417     }
 418
 419     // Asm->EOL("Region start");
 420
 421     if (!S.EndLabel)
 422       EndLabelPtr = (intptr_t)EndFunction;
 423     else
 424       EndLabelPtr = JCE->getLabelAddress(S.EndLabel);
 425
 426     JCE->emitInt32(EndLabelPtr - BeginLabelPtr);
 427     //Asm->EOL("Region length");
 428
 429     if (!S.PadLabel) {
 430       JCE->emitInt32(0);
 431     } else {
 432       unsigned PadLabelPtr = JCE->getLabelAddress(S.PadLabel);
 433       JCE->emitInt32(PadLabelPtr - (intptr_t)StartFunction);
 434     }
 435     // Asm->EOL("Landing pad");
 436
 437     JCE->emitULEB128Bytes(S.Action);
 438     // Asm->EOL("Action");
 439   }
 440
 441   // Emit the actions.
 442   for (unsigned I = 0, N = Actions.size(); I != N; ++I) {
 443     ActionEntry &Action = Actions[I];
 444
 445     JCE->emitSLEB128Bytes(Action.ValueForTypeID);
 446     //Asm->EOL("TypeInfo index");
 447     JCE->emitSLEB128Bytes(Action.NextAction);
 448     //Asm->EOL("Next action");
 449   }
 450
 451   // Emit the type ids.
 452   for (unsigned M = TypeInfos.size(); M; --M) {
 453     const GlobalVariable *GV = TypeInfos[M - 1];
 454
 455     if (GV) {
 456       if (TD->getPointerSize() == sizeof(int32_t))
 457         JCE->emitInt32((intptr_t)Jit.getOrEmitGlobalVariable(GV));
 458       else
 459         JCE->emitInt64((intptr_t)Jit.getOrEmitGlobalVariable(GV));
 460     } else {
 461       if (TD->getPointerSize() == sizeof(int32_t))
 462         JCE->emitInt32(0);
 463       else
 464         JCE->emitInt64(0);
 465     }
 466     // Asm->EOL("TypeInfo");
 467   }
 468
 469   // Emit the filter typeids.
 470   for (unsigned j = 0, M = FilterIds.size(); j < M; ++j) {
 471     unsigned TypeID = FilterIds[j];
 472     JCE->emitULEB128Bytes(TypeID);
 473     //Asm->EOL("Filter TypeInfo index");
 474   }
 475
 476   JCE->emitAlignmentWithFill(4, 0);
 477
 478   return DwarfExceptionTable;
 479 }
 480
 481 unsigned char*
 482 JITDwarfEmitter::EmitCommonEHFrame(const Function* Personality) const {
 483   unsigned PointerSize = TD->getPointerSize();
 484   int stackGrowth = stackGrowthDirection == TargetFrameInfo::StackGrowsUp ?
 485           PointerSize : -PointerSize;
 486
 487   unsigned char* StartCommonPtr = (unsigned char*)JCE->getCurrentPCValue();
 488   // EH Common Frame header
 489   JCE->allocateSpace(4, 0);
 490   unsigned char* FrameCommonBeginPtr = (unsigned char*)JCE->getCurrentPCValue();
 491   JCE->emitInt32((int)0);
 492   JCE->emitByte(dwarf::DW_CIE_VERSION);
 493   JCE->emitString(Personality ? "zPLR" : "zR");
 494   JCE->emitULEB128Bytes(1);
 495   JCE->emitSLEB128Bytes(stackGrowth);
 496   JCE->emitByte(RI->getDwarfRegNum(RI->getRARegister(), true));
 497
 498   if (Personality) {
 499     // Augmentation Size: 3 small ULEBs of one byte each, and the personality
 500     // function which size is PointerSize.
 501     JCE->emitULEB128Bytes(3 + PointerSize);
 502
 503     // We set the encoding of the personality as direct encoding because we use
 504     // the function pointer. The encoding is not relative because the current
 505     // PC value may be bigger than the personality function pointer.
 506     if (PointerSize == 4) {
 507       JCE->emitByte(dwarf::DW_EH_PE_sdata4);
 508       JCE->emitInt32(((intptr_t)Jit.getPointerToGlobal(Personality)));
 509     } else {
 510       JCE->emitByte(dwarf::DW_EH_PE_sdata8);
 511       JCE->emitInt64(((intptr_t)Jit.getPointerToGlobal(Personality)));
 512     }
 513
 514     // LSDA encoding: This must match the encoding used in EmitEHFrame ()
 515     if (PointerSize == 4)
 516       JCE->emitULEB128Bytes(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
 517     else
 518       JCE->emitULEB128Bytes(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8);
 519     JCE->emitULEB128Bytes(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
 520   } else {
 521     JCE->emitULEB128Bytes(1);
 522     JCE->emitULEB128Bytes(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
 523   }
 524
 525   std::vector<MachineMove> Moves;
 526   RI->getInitialFrameState(Moves);
 527   EmitFrameMoves(0, Moves);
 528
 529   JCE->emitAlignmentWithFill(PointerSize, dwarf::DW_CFA_nop);
 530
 531   JCE->emitInt32At((uintptr_t*)StartCommonPtr,
 532                    (uintptr_t)((unsigned char*)JCE->getCurrentPCValue() -
 533                                FrameCommonBeginPtr));
 534
 535   return StartCommonPtr;
 536 }
 537
 538
 539 unsigned char*
 540 JITDwarfEmitter::EmitEHFrame(const Function* Personality,
 541                              unsigned char* StartCommonPtr,
 542                              unsigned char* StartFunction,
 543                              unsigned char* EndFunction,
 544                              unsigned char* ExceptionTable) const {
 545   unsigned PointerSize = TD->getPointerSize();
 546
 547   // EH frame header.
 548   unsigned char* StartEHPtr = (unsigned char*)JCE->getCurrentPCValue();
 549   JCE->allocateSpace(4, 0);
 550   unsigned char* FrameBeginPtr = (unsigned char*)JCE->getCurrentPCValue();
 551   // FDE CIE Offset
 552   JCE->emitInt32(FrameBeginPtr - StartCommonPtr);
 553   JCE->emitInt32(StartFunction - (unsigned char*)JCE->getCurrentPCValue());
 554   JCE->emitInt32(EndFunction - StartFunction);
 555
 556   // If there is a personality and landing pads then point to the language
 557   // specific data area in the exception table.
 558   if (Personality) {
 559     JCE->emitULEB128Bytes(PointerSize == 4 ? 4 : 8);
 560
 561     if (PointerSize == 4) {
 562       if (!MMI->getLandingPads().empty())
 563         JCE->emitInt32(ExceptionTable-(unsigned char*)JCE->getCurrentPCValue());
 564       else
 565         JCE->emitInt32((int)0);
 566     } else {
 567       if (!MMI->getLandingPads().empty())
 568         JCE->emitInt64(ExceptionTable-(unsigned char*)JCE->getCurrentPCValue());
 569       else
 570         JCE->emitInt64((int)0);
 571     }
 572   } else {
 573     JCE->emitULEB128Bytes(0);
 574   }
 575
 576   // Indicate locations of function specific  callee saved registers in
 577   // frame.
 578   EmitFrameMoves((intptr_t)StartFunction, MMI->getFrameMoves());
 579
 580   JCE->emitAlignmentWithFill(PointerSize, dwarf::DW_CFA_nop);
 581
 582   // Indicate the size of the table
 583   JCE->emitInt32At((uintptr_t*)StartEHPtr,
 584                    (uintptr_t)((unsigned char*)JCE->getCurrentPCValue() -
 585                                StartEHPtr));
 586
 587   // Double zeroes for the unwind runtime
 588   if (PointerSize == 8) {
 589     JCE->emitInt64(0);
 590     JCE->emitInt64(0);
 591   } else {
 592     JCE->emitInt32(0);
 593     JCE->emitInt32(0);
 594   }
 595
 596   return StartEHPtr;
 597 }