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/TargetFrameLowering.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.getFrameLowering()->getStackGrowthDirection();
  47   RI = TM.getRegisterInfo();
  48   TFI = TM.getFrameLowering();
  49   JCE = &jce;
  50
  51   unsigned char* ExceptionTable = EmitExceptionTable(&F, StartFunction,
  52                                                      EndFunction);
  53
  54   unsigned char* Result = 0;
  55
  56   const std::vector<const Function *> Personalities = MMI->getPersonalities();
  57   EHFramePtr = EmitCommonEHFrame(Personalities[MMI->getPersonalityIndex()]);
  58
  59   Result = EmitEHFrame(Personalities[MMI->getPersonalityIndex()], EHFramePtr,
  60                        StartFunction, EndFunction, ExceptionTable);
  61
  62   return Result;
  63 }
  64
  65
  66 void
  67 JITDwarfEmitter::EmitFrameMoves(intptr_t BaseLabelPtr,
  68                                 const std::vector<MachineMove> &Moves) const {
  69   unsigned PointerSize = TD->getPointerSize();
  70   int stackGrowth = stackGrowthDirection == TargetFrameLowering::StackGrowsUp ?
  71           PointerSize : -PointerSize;
  72   MCSymbol *BaseLabel = 0;
  73
  74   for (unsigned i = 0, N = Moves.size(); i < N; ++i) {
  75     const MachineMove &Move = Moves[i];
  76     MCSymbol *Label = Move.getLabel();
  77
  78     // Throw out move if the label is invalid.
  79     if (Label && (*JCE->getLabelLocations())[Label] == 0)
  80       continue;
  81
  82     intptr_t LabelPtr = 0;
  83     if (Label) LabelPtr = JCE->getLabelAddress(Label);
  84
  85     const MachineLocation &Dst = Move.getDestination();
  86     const MachineLocation &Src = Move.getSource();
  87
  88     // Advance row if new location.
  89     if (BaseLabelPtr && Label && BaseLabel != Label) {
  90       JCE->emitByte(dwarf::DW_CFA_advance_loc4);
  91       JCE->emitInt32(LabelPtr - BaseLabelPtr);
  92
  93       BaseLabel = Label;
  94       BaseLabelPtr = LabelPtr;
  95     }
  96
  97     // If advancing cfa.
  98     if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
  99       if (!Src.isReg()) {
 100         if (Src.getReg() == MachineLocation::VirtualFP) {
 101           JCE->emitByte(dwarf::DW_CFA_def_cfa_offset);
 102         } else {
 103           JCE->emitByte(dwarf::DW_CFA_def_cfa);
 104           JCE->emitULEB128Bytes(RI->getDwarfRegNum(Src.getReg(), true));
 105         }
 106
 107         JCE->emitULEB128Bytes(-Src.getOffset());
 108       } else {
 109         llvm_unreachable("Machine move not supported yet.");
 110       }
 111     } else if (Src.isReg() &&
 112       Src.getReg() == MachineLocation::VirtualFP) {
 113       if (Dst.isReg()) {
 114         JCE->emitByte(dwarf::DW_CFA_def_cfa_register);
 115         JCE->emitULEB128Bytes(RI->getDwarfRegNum(Dst.getReg(), true));
 116       } else {
 117         llvm_unreachable("Machine move not supported yet.");
 118       }
 119     } else {
 120       unsigned Reg = RI->getDwarfRegNum(Src.getReg(), true);
 121       int Offset = Dst.getOffset() / stackGrowth;
 122
 123       if (Offset < 0) {
 124         JCE->emitByte(dwarf::DW_CFA_offset_extended_sf);
 125         JCE->emitULEB128Bytes(Reg);
 126         JCE->emitSLEB128Bytes(Offset);
 127       } else if (Reg < 64) {
 128         JCE->emitByte(dwarf::DW_CFA_offset + Reg);
 129         JCE->emitULEB128Bytes(Offset);
 130       } else {
 131         JCE->emitByte(dwarf::DW_CFA_offset_extended);
 132         JCE->emitULEB128Bytes(Reg);
 133         JCE->emitULEB128Bytes(Offset);
 134       }
 135     }
 136   }
 137 }
 138
 139 /// SharedTypeIds - How many leading type ids two landing pads have in common.
 140 static unsigned SharedTypeIds(const LandingPadInfo *L,
 141                               const LandingPadInfo *R) {
 142   const std::vector<int> &LIds = L->TypeIds, &RIds = R->TypeIds;
 143   unsigned LSize = LIds.size(), RSize = RIds.size();
 144   unsigned MinSize = LSize < RSize ? LSize : RSize;
 145   unsigned Count = 0;
 146
 147   for (; Count != MinSize; ++Count)
 148     if (LIds[Count] != RIds[Count])
 149       return Count;
 150
 151   return Count;
 152 }
 153
 154
 155 /// PadLT - Order landing pads lexicographically by type id.
 156 static bool PadLT(const LandingPadInfo *L, const LandingPadInfo *R) {
 157   const std::vector<int> &LIds = L->TypeIds, &RIds = R->TypeIds;
 158   unsigned LSize = LIds.size(), RSize = RIds.size();
 159   unsigned MinSize = LSize < RSize ? LSize : RSize;
 160
 161   for (unsigned i = 0; i != MinSize; ++i)
 162     if (LIds[i] != RIds[i])
 163       return LIds[i] < RIds[i];
 164
 165   return LSize < RSize;
 166 }
 167
 168 namespace {
 169
 170 /// ActionEntry - Structure describing an entry in the actions table.
 171 struct ActionEntry {
 172   int ValueForTypeID; // The value to write - may not be equal to the type id.
 173   int NextAction;
 174   struct ActionEntry *Previous;
 175 };
 176
 177 /// PadRange - Structure holding a try-range and the associated landing pad.
 178 struct PadRange {
 179   // The index of the landing pad.
 180   unsigned PadIndex;
 181   // The index of the begin and end labels in the landing pad's label lists.
 182   unsigned RangeIndex;
 183 };
 184
 185 typedef DenseMap<MCSymbol*, PadRange> RangeMapType;
 186
 187 /// CallSiteEntry - Structure describing an entry in the call-site table.
 188 struct CallSiteEntry {
 189   MCSymbol *BeginLabel; // zero indicates the start of the function.
 190   MCSymbol *EndLabel;   // zero indicates the end of the function.
 191   MCSymbol *PadLabel;   // zero indicates that there is no landing pad.
 192   unsigned Action;
 193 };
 194
 195 }
 196
 197 unsigned char* JITDwarfEmitter::EmitExceptionTable(MachineFunction* MF,
 198                                          unsigned char* StartFunction,
 199                                          unsigned char* EndFunction) const {
 200   assert(MMI && "MachineModuleInfo not registered!");
 201
 202   // Map all labels and get rid of any dead landing pads.
 203   MMI->TidyLandingPads(JCE->getLabelLocations());
 204
 205   const std::vector<const GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
 206   const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
 207   const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
 208   if (PadInfos.empty()) return 0;
 209
 210   // Sort the landing pads in order of their type ids.  This is used to fold
 211   // duplicate actions.
 212   SmallVector<const LandingPadInfo *, 64> LandingPads;
 213   LandingPads.reserve(PadInfos.size());
 214   for (unsigned i = 0, N = PadInfos.size(); i != N; ++i)
 215     LandingPads.push_back(&PadInfos[i]);
 216   std::sort(LandingPads.begin(), LandingPads.end(), PadLT);
 217
 218   // Negative type ids index into FilterIds, positive type ids index into
 219   // TypeInfos.  The value written for a positive type id is just the type
 220   // id itself.  For a negative type id, however, the value written is the
 221   // (negative) byte offset of the corresponding FilterIds entry.  The byte
 222   // offset is usually equal to the type id, because the FilterIds entries
 223   // are written using a variable width encoding which outputs one byte per
 224   // entry as long as the value written is not too large, but can differ.
 225   // This kind of complication does not occur for positive type ids because
 226   // type infos are output using a fixed width encoding.
 227   // FilterOffsets[i] holds the byte offset corresponding to FilterIds[i].
 228   SmallVector<int, 16> FilterOffsets;
 229   FilterOffsets.reserve(FilterIds.size());
 230   int Offset = -1;
 231   for(std::vector<unsigned>::const_iterator I = FilterIds.begin(),
 232     E = FilterIds.end(); I != E; ++I) {
 233     FilterOffsets.push_back(Offset);
 234     Offset -= MCAsmInfo::getULEB128Size(*I);
 235   }
 236
 237   // Compute the actions table and gather the first action index for each
 238   // landing pad site.
 239   SmallVector<ActionEntry, 32> Actions;
 240   SmallVector<unsigned, 64> FirstActions;
 241   FirstActions.reserve(LandingPads.size());
 242
 243   int FirstAction = 0;
 244   unsigned SizeActions = 0;
 245   for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
 246     const LandingPadInfo *LP = LandingPads[i];
 247     const std::vector<int> &TypeIds = LP->TypeIds;
 248     const unsigned NumShared = i ? SharedTypeIds(LP, LandingPads[i-1]) : 0;
 249     unsigned SizeSiteActions = 0;
 250
 251     if (NumShared < TypeIds.size()) {
 252       unsigned SizeAction = 0;
 253       ActionEntry *PrevAction = 0;
 254
 255       if (NumShared) {
 256         const unsigned SizePrevIds = LandingPads[i-1]->TypeIds.size();
 257         assert(Actions.size());
 258         PrevAction = &Actions.back();
 259         SizeAction = MCAsmInfo::getSLEB128Size(PrevAction->NextAction) +
 260           MCAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
 261         for (unsigned j = NumShared; j != SizePrevIds; ++j) {
 262           SizeAction -= MCAsmInfo::getSLEB128Size(PrevAction->ValueForTypeID);
 263           SizeAction += -PrevAction->NextAction;
 264           PrevAction = PrevAction->Previous;
 265         }
 266       }
 267
 268       // Compute the actions.
 269       for (unsigned I = NumShared, M = TypeIds.size(); I != M; ++I) {
 270         int TypeID = TypeIds[I];
 271         assert(-1-TypeID < (int)FilterOffsets.size() && "Unknown filter id!");
 272         int ValueForTypeID = TypeID < 0 ? FilterOffsets[-1 - TypeID] : TypeID;
 273         unsigned SizeTypeID = MCAsmInfo::getSLEB128Size(ValueForTypeID);
 274
 275         int NextAction = SizeAction ? -(SizeAction + SizeTypeID) : 0;
 276         SizeAction = SizeTypeID + MCAsmInfo::getSLEB128Size(NextAction);
 277         SizeSiteActions += SizeAction;
 278
 279         ActionEntry Action = {ValueForTypeID, NextAction, PrevAction};
 280         Actions.push_back(Action);
 281
 282         PrevAction = &Actions.back();
 283       }
 284
 285       // Record the first action of the landing pad site.
 286       FirstAction = SizeActions + SizeSiteActions - SizeAction + 1;
 287     } // else identical - re-use previous FirstAction
 288
 289     FirstActions.push_back(FirstAction);
 290
 291     // Compute this sites contribution to size.
 292     SizeActions += SizeSiteActions;
 293   }
 294
 295   // Compute the call-site table.  Entries must be ordered by address.
 296   SmallVector<CallSiteEntry, 64> CallSites;
 297
 298   RangeMapType PadMap;
 299   for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
 300     const LandingPadInfo *LandingPad = LandingPads[i];
 301     for (unsigned j=0, E = LandingPad->BeginLabels.size(); j != E; ++j) {
 302       MCSymbol *BeginLabel = LandingPad->BeginLabels[j];
 303       assert(!PadMap.count(BeginLabel) && "Duplicate landing pad labels!");
 304       PadRange P = { i, j };
 305       PadMap[BeginLabel] = P;
 306     }
 307   }
 308
 309   bool MayThrow = false;
 310   MCSymbol *LastLabel = 0;
 311   for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
 312         I != E; ++I) {
 313     for (MachineBasicBlock::const_iterator MI = I->begin(), E = I->end();
 314           MI != E; ++MI) {
 315       if (!MI->isLabel()) {
 316         MayThrow |= MI->getDesc().isCall();
 317         continue;
 318       }
 319
 320       MCSymbol *BeginLabel = MI->getOperand(0).getMCSymbol();
 321       assert(BeginLabel && "Invalid label!");
 322
 323       if (BeginLabel == LastLabel)
 324         MayThrow = false;
 325
 326       RangeMapType::iterator L = PadMap.find(BeginLabel);
 327
 328       if (L == PadMap.end())
 329         continue;
 330
 331       PadRange P = L->second;
 332       const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
 333
 334       assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
 335               "Inconsistent landing pad map!");
 336
 337       // If some instruction between the previous try-range and this one may
 338       // throw, create a call-site entry with no landing pad for the region
 339       // between the try-ranges.
 340       if (MayThrow) {
 341         CallSiteEntry Site = {LastLabel, BeginLabel, 0, 0};
 342         CallSites.push_back(Site);
 343       }
 344
 345       LastLabel = LandingPad->EndLabels[P.RangeIndex];
 346       CallSiteEntry Site = {BeginLabel, LastLabel,
 347         LandingPad->LandingPadLabel, FirstActions[P.PadIndex]};
 348
 349       assert(Site.BeginLabel && Site.EndLabel && Site.PadLabel &&
 350               "Invalid landing pad!");
 351
 352       // Try to merge with the previous call-site.
 353       if (CallSites.size()) {
 354         CallSiteEntry &Prev = CallSites.back();
 355         if (Site.PadLabel == Prev.PadLabel && Site.Action == Prev.Action) {
 356           // Extend the range of the previous entry.
 357           Prev.EndLabel = Site.EndLabel;
 358           continue;
 359         }
 360       }
 361
 362       // Otherwise, create a new call-site.
 363       CallSites.push_back(Site);
 364     }
 365   }
 366   // If some instruction between the previous try-range and the end of the
 367   // function may throw, create a call-site entry with no landing pad for the
 368   // region following the try-range.
 369   if (MayThrow) {
 370     CallSiteEntry Site = {LastLabel, 0, 0, 0};
 371     CallSites.push_back(Site);
 372   }
 373
 374   // Final tallies.
 375   unsigned SizeSites = CallSites.size() * (sizeof(int32_t) + // Site start.
 376                                             sizeof(int32_t) + // Site length.
 377                                             sizeof(int32_t)); // Landing pad.
 378   for (unsigned i = 0, e = CallSites.size(); i < e; ++i)
 379     SizeSites += MCAsmInfo::getULEB128Size(CallSites[i].Action);
 380
 381   unsigned SizeTypes = TypeInfos.size() * TD->getPointerSize();
 382
 383   unsigned TypeOffset = sizeof(int8_t) + // Call site format
 384                         // Call-site table length
 385                         MCAsmInfo::getULEB128Size(SizeSites) +
 386                         SizeSites + SizeActions + SizeTypes;
 387
 388   // Begin the exception table.
 389   JCE->emitAlignmentWithFill(4, 0);
 390   // Asm->EOL("Padding");
 391
 392   unsigned char* DwarfExceptionTable = (unsigned char*)JCE->getCurrentPCValue();
 393
 394   // Emit the header.
 395   JCE->emitByte(dwarf::DW_EH_PE_omit);
 396   // Asm->EOL("LPStart format (DW_EH_PE_omit)");
 397   JCE->emitByte(dwarf::DW_EH_PE_absptr);
 398   // Asm->EOL("TType format (DW_EH_PE_absptr)");
 399   JCE->emitULEB128Bytes(TypeOffset);
 400   // Asm->EOL("TType base offset");
 401   JCE->emitByte(dwarf::DW_EH_PE_udata4);
 402   // Asm->EOL("Call site format (DW_EH_PE_udata4)");
 403   JCE->emitULEB128Bytes(SizeSites);
 404   // Asm->EOL("Call-site table length");
 405
 406   // Emit the landing pad site information.
 407   for (unsigned i = 0; i < CallSites.size(); ++i) {
 408     CallSiteEntry &S = CallSites[i];
 409     intptr_t BeginLabelPtr = 0;
 410     intptr_t EndLabelPtr = 0;
 411
 412     if (!S.BeginLabel) {
 413       BeginLabelPtr = (intptr_t)StartFunction;
 414       JCE->emitInt32(0);
 415     } else {
 416       BeginLabelPtr = JCE->getLabelAddress(S.BeginLabel);
 417       JCE->emitInt32(BeginLabelPtr - (intptr_t)StartFunction);
 418     }
 419
 420     // Asm->EOL("Region start");
 421
 422     if (!S.EndLabel)
 423       EndLabelPtr = (intptr_t)EndFunction;
 424     else
 425       EndLabelPtr = JCE->getLabelAddress(S.EndLabel);
 426
 427     JCE->emitInt32(EndLabelPtr - BeginLabelPtr);
 428     //Asm->EOL("Region length");
 429
 430     if (!S.PadLabel) {
 431       JCE->emitInt32(0);
 432     } else {
 433       unsigned PadLabelPtr = JCE->getLabelAddress(S.PadLabel);
 434       JCE->emitInt32(PadLabelPtr - (intptr_t)StartFunction);
 435     }
 436     // Asm->EOL("Landing pad");
 437
 438     JCE->emitULEB128Bytes(S.Action);
 439     // Asm->EOL("Action");
 440   }
 441
 442   // Emit the actions.
 443   for (unsigned I = 0, N = Actions.size(); I != N; ++I) {
 444     ActionEntry &Action = Actions[I];
 445
 446     JCE->emitSLEB128Bytes(Action.ValueForTypeID);
 447     //Asm->EOL("TypeInfo index");
 448     JCE->emitSLEB128Bytes(Action.NextAction);
 449     //Asm->EOL("Next action");
 450   }
 451
 452   // Emit the type ids.
 453   for (unsigned M = TypeInfos.size(); M; --M) {
 454     const GlobalVariable *GV = TypeInfos[M - 1];
 455
 456     if (GV) {
 457       if (TD->getPointerSize() == sizeof(int32_t))
 458         JCE->emitInt32((intptr_t)Jit.getOrEmitGlobalVariable(GV));
 459       else
 460         JCE->emitInt64((intptr_t)Jit.getOrEmitGlobalVariable(GV));
 461     } else {
 462       if (TD->getPointerSize() == sizeof(int32_t))
 463         JCE->emitInt32(0);
 464       else
 465         JCE->emitInt64(0);
 466     }
 467     // Asm->EOL("TypeInfo");
 468   }
 469
 470   // Emit the filter typeids.
 471   for (unsigned j = 0, M = FilterIds.size(); j < M; ++j) {
 472     unsigned TypeID = FilterIds[j];
 473     JCE->emitULEB128Bytes(TypeID);
 474     //Asm->EOL("Filter TypeInfo index");
 475   }
 476
 477   JCE->emitAlignmentWithFill(4, 0);
 478
 479   return DwarfExceptionTable;
 480 }
 481
 482 unsigned char*
 483 JITDwarfEmitter::EmitCommonEHFrame(const Function* Personality) const {
 484   unsigned PointerSize = TD->getPointerSize();
 485   int stackGrowth = stackGrowthDirection == TargetFrameLowering::StackGrowsUp ?
 486           PointerSize : -PointerSize;
 487
 488   unsigned char* StartCommonPtr = (unsigned char*)JCE->getCurrentPCValue();
 489   // EH Common Frame header
 490   JCE->allocateSpace(4, 0);
 491   unsigned char* FrameCommonBeginPtr = (unsigned char*)JCE->getCurrentPCValue();
 492   JCE->emitInt32((int)0);
 493   JCE->emitByte(dwarf::DW_CIE_VERSION);
 494   JCE->emitString(Personality ? "zPLR" : "zR");
 495   JCE->emitULEB128Bytes(1);
 496   JCE->emitSLEB128Bytes(stackGrowth);
 497   JCE->emitByte(RI->getDwarfRegNum(RI->getRARegister(), true));
 498
 499   if (Personality) {
 500     // Augmentation Size: 3 small ULEBs of one byte each, and the personality
 501     // function which size is PointerSize.
 502     JCE->emitULEB128Bytes(3 + PointerSize);
 503
 504     // We set the encoding of the personality as direct encoding because we use
 505     // the function pointer. The encoding is not relative because the current
 506     // PC value may be bigger than the personality function pointer.
 507     if (PointerSize == 4) {
 508       JCE->emitByte(dwarf::DW_EH_PE_sdata4);
 509       JCE->emitInt32(((intptr_t)Jit.getPointerToGlobal(Personality)));
 510     } else {
 511       JCE->emitByte(dwarf::DW_EH_PE_sdata8);
 512       JCE->emitInt64(((intptr_t)Jit.getPointerToGlobal(Personality)));
 513     }
 514
 515     // LSDA encoding: This must match the encoding used in EmitEHFrame ()
 516     if (PointerSize == 4)
 517       JCE->emitULEB128Bytes(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
 518     else
 519       JCE->emitULEB128Bytes(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8);
 520     JCE->emitULEB128Bytes(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
 521   } else {
 522     JCE->emitULEB128Bytes(1);
 523     JCE->emitULEB128Bytes(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
 524   }
 525
 526   std::vector<MachineMove> Moves;
 527   TFI->getInitialFrameState(Moves);
 528   EmitFrameMoves(0, Moves);
 529
 530   JCE->emitAlignmentWithFill(PointerSize, dwarf::DW_CFA_nop);
 531
 532   JCE->emitInt32At((uintptr_t*)StartCommonPtr,
 533                    (uintptr_t)((unsigned char*)JCE->getCurrentPCValue() -
 534                                FrameCommonBeginPtr));
 535
 536   return StartCommonPtr;
 537 }
 538
 539
 540 unsigned char*
 541 JITDwarfEmitter::EmitEHFrame(const Function* Personality,
 542                              unsigned char* StartCommonPtr,
 543                              unsigned char* StartFunction,
 544                              unsigned char* EndFunction,
 545                              unsigned char* ExceptionTable) const {
 546   unsigned PointerSize = TD->getPointerSize();
 547
 548   // EH frame header.
 549   unsigned char* StartEHPtr = (unsigned char*)JCE->getCurrentPCValue();
 550   JCE->allocateSpace(4, 0);
 551   unsigned char* FrameBeginPtr = (unsigned char*)JCE->getCurrentPCValue();
 552   // FDE CIE Offset
 553   JCE->emitInt32(FrameBeginPtr - StartCommonPtr);
 554   JCE->emitInt32(StartFunction - (unsigned char*)JCE->getCurrentPCValue());
 555   JCE->emitInt32(EndFunction - StartFunction);
 556
 557   // If there is a personality and landing pads then point to the language
 558   // specific data area in the exception table.
 559   if (Personality) {
 560     JCE->emitULEB128Bytes(PointerSize == 4 ? 4 : 8);
 561
 562     if (PointerSize == 4) {
 563       if (!MMI->getLandingPads().empty())
 564         JCE->emitInt32(ExceptionTable-(unsigned char*)JCE->getCurrentPCValue());
 565       else
 566         JCE->emitInt32((int)0);
 567     } else {
 568       if (!MMI->getLandingPads().empty())
 569         JCE->emitInt64(ExceptionTable-(unsigned char*)JCE->getCurrentPCValue());
 570       else
 571         JCE->emitInt64((int)0);
 572     }
 573   } else {
 574     JCE->emitULEB128Bytes(0);
 575   }
 576
 577   // Indicate locations of function specific  callee saved registers in
 578   // frame.
 579   EmitFrameMoves((intptr_t)StartFunction, MMI->getFrameMoves());
 580
 581   JCE->emitAlignmentWithFill(PointerSize, dwarf::DW_CFA_nop);
 582
 583   // Indicate the size of the table
 584   JCE->emitInt32At((uintptr_t*)StartEHPtr,
 585                    (uintptr_t)((unsigned char*)JCE->getCurrentPCValue() -
 586                                StartEHPtr));
 587
 588   // Double zeroes for the unwind runtime
 589   if (PointerSize == 8) {
 590     JCE->emitInt64(0);
 591     JCE->emitInt64(0);
 592   } else {
 593     JCE->emitInt32(0);
 594     JCE->emitInt32(0);
 595   }
 596
 597   return StartEHPtr;
 598 }