include/llvm/BinaryFormat/Dwarf.h

   1 //===-- llvm/BinaryFormat/Dwarf.h ---Dwarf Constants-------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 /// \file
  10 /// This file contains constants used for implementing Dwarf
  11 /// debug support.
  12 ///
  13 /// For details on the Dwarf specfication see the latest DWARF Debugging
  14 /// Information Format standard document on http://www.dwarfstd.org. This
  15 /// file often includes support for non-released standard features.
  16 //
  17 //===----------------------------------------------------------------------===//
  18
  19 #ifndef LLVM_BINARYFORMAT_DWARF_H
  20 #define LLVM_BINARYFORMAT_DWARF_H
  21
  22 #include "llvm/ADT/Optional.h"
  23 #include "llvm/Support/Compiler.h"
  24 #include "llvm/Support/DataTypes.h"
  25 #include "llvm/Support/ErrorHandling.h"
  26 #include "llvm/Support/Format.h"
  27 #include "llvm/Support/FormatVariadicDetails.h"
  28 #include "llvm/ADT/Triple.h"
  29
  30 namespace llvm {
  31 class StringRef;
  32
  33 namespace dwarf {
  34
  35 //===----------------------------------------------------------------------===//
  36 // DWARF constants as gleaned from the DWARF Debugging Information Format V.5
  37 // reference manual http://www.dwarfstd.org/.
  38 //
  39
  40 // Do not mix the following two enumerations sets.  DW_TAG_invalid changes the
  41 // enumeration base type.
  42
  43 enum LLVMConstants : uint32_t {
  44   // LLVM mock tags (see also llvm/BinaryFormat/Dwarf.def).
  45   DW_TAG_invalid = ~0U,        // Tag for invalid results.
  46   DW_VIRTUALITY_invalid = ~0U, // Virtuality for invalid results.
  47   DW_MACINFO_invalid = ~0U,    // Macinfo type for invalid results.
  48
  49   // Other constants.
  50   DWARF_VERSION = 4,       // Default dwarf version we output.
  51   DW_PUBTYPES_VERSION = 2, // Section version number for .debug_pubtypes.
  52   DW_PUBNAMES_VERSION = 2, // Section version number for .debug_pubnames.
  53   DW_ARANGES_VERSION = 2,  // Section version number for .debug_aranges.
  54   // Identifiers we use to distinguish vendor extensions.
  55   DWARF_VENDOR_DWARF = 0, // Defined in v2 or later of the DWARF standard.
  56   DWARF_VENDOR_APPLE = 1,
  57   DWARF_VENDOR_BORLAND = 2,
  58   DWARF_VENDOR_GNU = 3,
  59   DWARF_VENDOR_GOOGLE = 4,
  60   DWARF_VENDOR_LLVM = 5,
  61   DWARF_VENDOR_MIPS = 6
  62 };
  63
  64 /// Constants that define the DWARF format as 32 or 64 bit.
  65 enum DwarfFormat : uint8_t { DWARF32, DWARF64 };
  66
  67 /// Special ID values that distinguish a CIE from a FDE in DWARF CFI.
  68 /// Not inside an enum because a 64-bit value is needed.
  69 /// @{
  70 const uint32_t DW_CIE_ID = UINT32_MAX;
  71 const uint64_t DW64_CIE_ID = UINT64_MAX;
  72 /// @}
  73
  74 /// Identifier of an invalid DIE offset in the .debug_info section.
  75 const uint32_t DW_INVALID_OFFSET = UINT32_MAX;
  76
  77 enum Tag : uint16_t {
  78 #define HANDLE_DW_TAG(ID, NAME, VERSION, VENDOR) DW_TAG_##NAME = ID,
  79 #include "llvm/BinaryFormat/Dwarf.def"
  80   DW_TAG_lo_user = 0x4080,
  81   DW_TAG_hi_user = 0xffff,
  82   DW_TAG_user_base = 0x1000 ///< Recommended base for user tags.
  83 };
  84
  85 inline bool isType(Tag T) {
  86   switch (T) {
  87   case DW_TAG_array_type:
  88   case DW_TAG_class_type:
  89   case DW_TAG_interface_type:
  90   case DW_TAG_enumeration_type:
  91   case DW_TAG_pointer_type:
  92   case DW_TAG_reference_type:
  93   case DW_TAG_rvalue_reference_type:
  94   case DW_TAG_string_type:
  95   case DW_TAG_structure_type:
  96   case DW_TAG_subroutine_type:
  97   case DW_TAG_union_type:
  98   case DW_TAG_ptr_to_member_type:
  99   case DW_TAG_set_type:
 100   case DW_TAG_subrange_type:
 101   case DW_TAG_base_type:
 102   case DW_TAG_const_type:
 103   case DW_TAG_file_type:
 104   case DW_TAG_packed_type:
 105   case DW_TAG_volatile_type:
 106   case DW_TAG_typedef:
 107     return true;
 108   default:
 109     return false;
 110   }
 111 }
 112
 113 /// Attributes.
 114 enum Attribute : uint16_t {
 115 #define HANDLE_DW_AT(ID, NAME, VERSION, VENDOR) DW_AT_##NAME = ID,
 116 #include "llvm/BinaryFormat/Dwarf.def"
 117   DW_AT_lo_user = 0x2000,
 118   DW_AT_hi_user = 0x3fff,
 119 };
 120
 121 enum Form : uint16_t {
 122 #define HANDLE_DW_FORM(ID, NAME, VERSION, VENDOR) DW_FORM_##NAME = ID,
 123 #include "llvm/BinaryFormat/Dwarf.def"
 124   DW_FORM_lo_user = 0x1f00, ///< Not specified by DWARF.
 125 };
 126
 127 enum LocationAtom {
 128 #define HANDLE_DW_OP(ID, NAME, VERSION, VENDOR) DW_OP_##NAME = ID,
 129 #include "llvm/BinaryFormat/Dwarf.def"
 130   DW_OP_lo_user = 0xe0,
 131   DW_OP_hi_user = 0xff,
 132   DW_OP_LLVM_fragment = 0x1000 ///< Only used in LLVM metadata.
 133 };
 134
 135 enum TypeKind : uint8_t {
 136 #define HANDLE_DW_ATE(ID, NAME, VERSION, VENDOR) DW_ATE_##NAME = ID,
 137 #include "llvm/BinaryFormat/Dwarf.def"
 138   DW_ATE_lo_user = 0x80,
 139   DW_ATE_hi_user = 0xff
 140 };
 141
 142 enum DecimalSignEncoding {
 143   // Decimal sign attribute values
 144   DW_DS_unsigned = 0x01,
 145   DW_DS_leading_overpunch = 0x02,
 146   DW_DS_trailing_overpunch = 0x03,
 147   DW_DS_leading_separate = 0x04,
 148   DW_DS_trailing_separate = 0x05
 149 };
 150
 151 enum EndianityEncoding {
 152   // Endianity attribute values
 153 #define HANDLE_DW_END(ID, NAME) DW_END_##NAME = ID,
 154 #include "llvm/BinaryFormat/Dwarf.def"
 155   DW_END_lo_user = 0x40,
 156   DW_END_hi_user = 0xff
 157 };
 158
 159 enum AccessAttribute {
 160   // Accessibility codes
 161   DW_ACCESS_public = 0x01,
 162   DW_ACCESS_protected = 0x02,
 163   DW_ACCESS_private = 0x03
 164 };
 165
 166 enum VisibilityAttribute {
 167   // Visibility codes
 168   DW_VIS_local = 0x01,
 169   DW_VIS_exported = 0x02,
 170   DW_VIS_qualified = 0x03
 171 };
 172
 173 enum VirtualityAttribute {
 174 #define HANDLE_DW_VIRTUALITY(ID, NAME) DW_VIRTUALITY_##NAME = ID,
 175 #include "llvm/BinaryFormat/Dwarf.def"
 176   DW_VIRTUALITY_max = 0x02
 177 };
 178
 179 enum DefaultedMemberAttribute {
 180 #define HANDLE_DW_DEFAULTED(ID, NAME) DW_DEFAULTED_##NAME = ID,
 181 #include "llvm/BinaryFormat/Dwarf.def"
 182   DW_DEFAULTED_max = 0x02
 183 };
 184
 185 enum SourceLanguage {
 186 #define HANDLE_DW_LANG(ID, NAME, LOWER_BOUND, VERSION, VENDOR)                 \
 187   DW_LANG_##NAME = ID,
 188 #include "llvm/BinaryFormat/Dwarf.def"
 189   DW_LANG_lo_user = 0x8000,
 190   DW_LANG_hi_user = 0xffff
 191 };
 192
 193 enum CaseSensitivity {
 194   // Identifier case codes
 195   DW_ID_case_sensitive = 0x00,
 196   DW_ID_up_case = 0x01,
 197   DW_ID_down_case = 0x02,
 198   DW_ID_case_insensitive = 0x03
 199 };
 200
 201 enum CallingConvention {
 202 // Calling convention codes
 203 #define HANDLE_DW_CC(ID, NAME) DW_CC_##NAME = ID,
 204 #include "llvm/BinaryFormat/Dwarf.def"
 205   DW_CC_lo_user = 0x40,
 206   DW_CC_hi_user = 0xff
 207 };
 208
 209 enum InlineAttribute {
 210   // Inline codes
 211   DW_INL_not_inlined = 0x00,
 212   DW_INL_inlined = 0x01,
 213   DW_INL_declared_not_inlined = 0x02,
 214   DW_INL_declared_inlined = 0x03
 215 };
 216
 217 enum ArrayDimensionOrdering {
 218   // Array ordering
 219   DW_ORD_row_major = 0x00,
 220   DW_ORD_col_major = 0x01
 221 };
 222
 223 enum DiscriminantList {
 224   // Discriminant descriptor values
 225   DW_DSC_label = 0x00,
 226   DW_DSC_range = 0x01
 227 };
 228
 229 /// Line Number Standard Opcode Encodings.
 230 enum LineNumberOps : uint8_t {
 231 #define HANDLE_DW_LNS(ID, NAME) DW_LNS_##NAME = ID,
 232 #include "llvm/BinaryFormat/Dwarf.def"
 233 };
 234
 235 /// Line Number Extended Opcode Encodings.
 236 enum LineNumberExtendedOps {
 237 #define HANDLE_DW_LNE(ID, NAME) DW_LNE_##NAME = ID,
 238 #include "llvm/BinaryFormat/Dwarf.def"
 239   DW_LNE_lo_user = 0x80,
 240   DW_LNE_hi_user = 0xff
 241 };
 242
 243 enum LineNumberEntryFormat {
 244 #define HANDLE_DW_LNCT(ID, NAME) DW_LNCT_##NAME = ID,
 245 #include "llvm/BinaryFormat/Dwarf.def"
 246   DW_LNCT_lo_user = 0x2000,
 247   DW_LNCT_hi_user = 0x3fff,
 248 };
 249
 250 enum MacinfoRecordType {
 251   // Macinfo Type Encodings
 252   DW_MACINFO_define = 0x01,
 253   DW_MACINFO_undef = 0x02,
 254   DW_MACINFO_start_file = 0x03,
 255   DW_MACINFO_end_file = 0x04,
 256   DW_MACINFO_vendor_ext = 0xff
 257 };
 258
 259 /// DWARF v5 macro information entry type encodings.
 260 enum MacroEntryType {
 261 #define HANDLE_DW_MACRO(ID, NAME) DW_MACRO_##NAME = ID,
 262 #include "llvm/BinaryFormat/Dwarf.def"
 263   DW_MACRO_lo_user = 0xe0,
 264   DW_MACRO_hi_user = 0xff
 265 };
 266
 267 /// DWARF v5 range list entry encoding values.
 268 enum RangeListEntries {
 269 #define HANDLE_DW_RLE(ID, NAME) DW_RLE_##NAME = ID,
 270 #include "llvm/BinaryFormat/Dwarf.def"
 271 };
 272
 273 /// Call frame instruction encodings.
 274 enum CallFrameInfo {
 275 #define HANDLE_DW_CFA(ID, NAME) DW_CFA_##NAME = ID,
 276 #define HANDLE_DW_CFA_PRED(ID, NAME, ARCH) DW_CFA_##NAME = ID,
 277 #include "llvm/BinaryFormat/Dwarf.def"
 278   DW_CFA_extended = 0x00,
 279
 280   DW_CFA_lo_user = 0x1c,
 281   DW_CFA_hi_user = 0x3f
 282 };
 283
 284 enum Constants {
 285   // Children flag
 286   DW_CHILDREN_no = 0x00,
 287   DW_CHILDREN_yes = 0x01,
 288
 289   DW_EH_PE_absptr = 0x00,
 290   DW_EH_PE_omit = 0xff,
 291   DW_EH_PE_uleb128 = 0x01,
 292   DW_EH_PE_udata2 = 0x02,
 293   DW_EH_PE_udata4 = 0x03,
 294   DW_EH_PE_udata8 = 0x04,
 295   DW_EH_PE_sleb128 = 0x09,
 296   DW_EH_PE_sdata2 = 0x0A,
 297   DW_EH_PE_sdata4 = 0x0B,
 298   DW_EH_PE_sdata8 = 0x0C,
 299   DW_EH_PE_signed = 0x08,
 300   DW_EH_PE_pcrel = 0x10,
 301   DW_EH_PE_textrel = 0x20,
 302   DW_EH_PE_datarel = 0x30,
 303   DW_EH_PE_funcrel = 0x40,
 304   DW_EH_PE_aligned = 0x50,
 305   DW_EH_PE_indirect = 0x80
 306 };
 307
 308 /// Constants for location lists in DWARF v5.
 309 enum LocationListEntry : unsigned char {
 310   DW_LLE_end_of_list = 0x00,
 311   DW_LLE_base_addressx = 0x01,
 312   DW_LLE_startx_endx = 0x02,
 313   DW_LLE_startx_length = 0x03,
 314   DW_LLE_offset_pair = 0x04,
 315   DW_LLE_default_location = 0x05,
 316   DW_LLE_base_address = 0x06,
 317   DW_LLE_start_end = 0x07,
 318   DW_LLE_start_length = 0x08
 319 };
 320
 321 /// Constants for the DW_APPLE_PROPERTY_attributes attribute.
 322 /// Keep this list in sync with clang's DeclSpec.h ObjCPropertyAttributeKind!
 323 enum ApplePropertyAttributes {
 324 #define HANDLE_DW_APPLE_PROPERTY(ID, NAME) DW_APPLE_PROPERTY_##NAME = ID,
 325 #include "llvm/BinaryFormat/Dwarf.def"
 326 };
 327
 328 /// Constants for unit types in DWARF v5.
 329 enum UnitType : unsigned char {
 330 #define HANDLE_DW_UT(ID, NAME) DW_UT_##NAME = ID,
 331 #include "llvm/BinaryFormat/Dwarf.def"
 332   DW_UT_lo_user = 0x80,
 333   DW_UT_hi_user = 0xff
 334 };
 335
 336 enum Index {
 337 #define HANDLE_DW_IDX(ID, NAME) DW_IDX_##NAME = ID,
 338 #include "llvm/BinaryFormat/Dwarf.def"
 339   DW_IDX_lo_user = 0x2000,
 340   DW_IDX_hi_user = 0x3fff
 341 };
 342
 343 inline bool isUnitType(uint8_t UnitType) {
 344   switch (UnitType) {
 345   case DW_UT_compile:
 346   case DW_UT_type:
 347   case DW_UT_partial:
 348   case DW_UT_skeleton:
 349   case DW_UT_split_compile:
 350   case DW_UT_split_type:
 351     return true;
 352   default:
 353     return false;
 354   }
 355 }
 356
 357 inline bool isUnitType(dwarf::Tag T) {
 358   switch (T) {
 359   case DW_TAG_compile_unit:
 360   case DW_TAG_type_unit:
 361   case DW_TAG_partial_unit:
 362   case DW_TAG_skeleton_unit:
 363     return true;
 364   default:
 365     return false;
 366   }
 367 }
 368
 369 // Constants for the DWARF v5 Accelerator Table Proposal
 370 enum AcceleratorTable {
 371   // Data layout descriptors.
 372   DW_ATOM_null = 0u,       ///  Marker as the end of a list of atoms.
 373   DW_ATOM_die_offset = 1u, // DIE offset in the debug_info section.
 374   DW_ATOM_cu_offset = 2u, // Offset of the compile unit header that contains the
 375                           // item in question.
 376   DW_ATOM_die_tag = 3u,   // A tag entry.
 377   DW_ATOM_type_flags = 4u, // Set of flags for a type.
 378
 379   DW_ATOM_type_type_flags = 5u, // Dsymutil type extension.
 380   DW_ATOM_qual_name_hash = 6u,  // Dsymutil qualified hash extension.
 381
 382   // DW_ATOM_type_flags values.
 383
 384   // Always set for C++, only set for ObjC if this is the @implementation for a
 385   // class.
 386   DW_FLAG_type_implementation = 2u,
 387
 388   // Hash functions.
 389
 390   // Daniel J. Bernstein hash.
 391   DW_hash_function_djb = 0u
 392 };
 393
 394 // Constants for the GNU pubnames/pubtypes extensions supporting gdb index.
 395 enum GDBIndexEntryKind {
 396   GIEK_NONE,
 397   GIEK_TYPE,
 398   GIEK_VARIABLE,
 399   GIEK_FUNCTION,
 400   GIEK_OTHER,
 401   GIEK_UNUSED5,
 402   GIEK_UNUSED6,
 403   GIEK_UNUSED7
 404 };
 405
 406 enum GDBIndexEntryLinkage { GIEL_EXTERNAL, GIEL_STATIC };
 407
 408 /// \defgroup DwarfConstantsDumping Dwarf constants dumping functions
 409 ///
 410 /// All these functions map their argument's value back to the
 411 /// corresponding enumerator name or return an empty StringRef if the value
 412 /// isn't known.
 413 ///
 414 /// @{
 415 StringRef TagString(unsigned Tag);
 416 StringRef ChildrenString(unsigned Children);
 417 StringRef AttributeString(unsigned Attribute);
 418 StringRef FormEncodingString(unsigned Encoding);
 419 StringRef OperationEncodingString(unsigned Encoding);
 420 StringRef AttributeEncodingString(unsigned Encoding);
 421 StringRef DecimalSignString(unsigned Sign);
 422 StringRef EndianityString(unsigned Endian);
 423 StringRef AccessibilityString(unsigned Access);
 424 StringRef VisibilityString(unsigned Visibility);
 425 StringRef VirtualityString(unsigned Virtuality);
 426 StringRef LanguageString(unsigned Language);
 427 StringRef CaseString(unsigned Case);
 428 StringRef ConventionString(unsigned Convention);
 429 StringRef InlineCodeString(unsigned Code);
 430 StringRef ArrayOrderString(unsigned Order);
 431 StringRef LNStandardString(unsigned Standard);
 432 StringRef LNExtendedString(unsigned Encoding);
 433 StringRef MacinfoString(unsigned Encoding);
 434 StringRef RangeListEncodingString(unsigned Encoding);
 435 StringRef CallFrameString(unsigned Encoding, Triple::ArchType Arch);
 436 StringRef ApplePropertyString(unsigned);
 437 StringRef UnitTypeString(unsigned);
 438 StringRef AtomTypeString(unsigned Atom);
 439 StringRef GDBIndexEntryKindString(GDBIndexEntryKind Kind);
 440 StringRef GDBIndexEntryLinkageString(GDBIndexEntryLinkage Linkage);
 441 StringRef IndexString(unsigned Idx);
 442 /// @}
 443
 444 /// \defgroup DwarfConstantsParsing Dwarf constants parsing functions
 445 ///
 446 /// These functions map their strings back to the corresponding enumeration
 447 /// value or return 0 if there is none, except for these exceptions:
 448 ///
 449 /// \li \a getTag() returns \a DW_TAG_invalid on invalid input.
 450 /// \li \a getVirtuality() returns \a DW_VIRTUALITY_invalid on invalid input.
 451 /// \li \a getMacinfo() returns \a DW_MACINFO_invalid on invalid input.
 452 ///
 453 /// @{
 454 unsigned getTag(StringRef TagString);
 455 unsigned getOperationEncoding(StringRef OperationEncodingString);
 456 unsigned getVirtuality(StringRef VirtualityString);
 457 unsigned getLanguage(StringRef LanguageString);
 458 unsigned getCallingConvention(StringRef LanguageString);
 459 unsigned getAttributeEncoding(StringRef EncodingString);
 460 unsigned getMacinfo(StringRef MacinfoString);
 461 /// @}
 462
 463 /// \defgroup DwarfConstantsVersioning Dwarf version for constants
 464 ///
 465 /// For constants defined by DWARF, returns the DWARF version when the constant
 466 /// was first defined. For vendor extensions, if there is a version-related
 467 /// policy for when to emit it, returns a version number for that policy.
 468 /// Otherwise returns 0.
 469 ///
 470 /// @{
 471 unsigned TagVersion(Tag T);
 472 unsigned AttributeVersion(Attribute A);
 473 unsigned FormVersion(Form F);
 474 unsigned OperationVersion(LocationAtom O);
 475 unsigned AttributeEncodingVersion(TypeKind E);
 476 unsigned LanguageVersion(SourceLanguage L);
 477 /// @}
 478
 479 /// \defgroup DwarfConstantsVendor Dwarf "vendor" for constants
 480 ///
 481 /// These functions return an identifier describing "who" defined the constant,
 482 /// either the DWARF standard itself or the vendor who defined the extension.
 483 ///
 484 /// @{
 485 unsigned TagVendor(Tag T);
 486 unsigned AttributeVendor(Attribute A);
 487 unsigned FormVendor(Form F);
 488 unsigned OperationVendor(LocationAtom O);
 489 unsigned AttributeEncodingVendor(TypeKind E);
 490 unsigned LanguageVendor(SourceLanguage L);
 491 /// @}
 492
 493 Optional<unsigned> LanguageLowerBound(SourceLanguage L);
 494
 495 /// A helper struct providing information about the byte size of DW_FORM
 496 /// values that vary in size depending on the DWARF version, address byte
 497 /// size, or DWARF32/DWARF64.
 498 struct FormParams {
 499   uint16_t Version;
 500   uint8_t AddrSize;
 501   DwarfFormat Format;
 502
 503   /// The definition of the size of form DW_FORM_ref_addr depends on the
 504   /// version. In DWARF v2 it's the size of an address; after that, it's the
 505   /// size of a reference.
 506   uint8_t getRefAddrByteSize() const {
 507     if (Version == 2)
 508       return AddrSize;
 509     return getDwarfOffsetByteSize();
 510   }
 511
 512   /// The size of a reference is determined by the DWARF 32/64-bit format.
 513   uint8_t getDwarfOffsetByteSize() const {
 514     switch (Format) {
 515     case DwarfFormat::DWARF32:
 516       return 4;
 517     case DwarfFormat::DWARF64:
 518       return 8;
 519     }
 520     llvm_unreachable("Invalid Format value");
 521   }
 522
 523   explicit operator bool() const { return Version && AddrSize; }
 524 };
 525
 526 /// Get the fixed byte size for a given form.
 527 ///
 528 /// If the form has a fixed byte size, then an Optional with a value will be
 529 /// returned. If the form is always encoded using a variable length storage
 530 /// format (ULEB or SLEB numbers or blocks) then None will be returned.
 531 ///
 532 /// \param Form DWARF form to get the fixed byte size for.
 533 /// \param Params DWARF parameters to help interpret forms.
 534 /// \returns Optional<uint8_t> value with the fixed byte size or None if
 535 /// \p Form doesn't have a fixed byte size.
 536 Optional<uint8_t> getFixedFormByteSize(dwarf::Form Form, FormParams Params);
 537
 538 /// Tells whether the specified form is defined in the specified version,
 539 /// or is an extension if extensions are allowed.
 540 bool isValidFormForVersion(Form F, unsigned Version, bool ExtensionsOk = true);
 541
 542 /// Returns the symbolic string representing Val when used as a value
 543 /// for attribute Attr.
 544 StringRef AttributeValueString(uint16_t Attr, unsigned Val);
 545
 546 /// Returns the symbolic string representing Val when used as a value
 547 /// for atom Atom.
 548 StringRef AtomValueString(uint16_t Atom, unsigned Val);
 549
 550 /// Describes an entry of the various gnu_pub* debug sections.
 551 ///
 552 /// The gnu_pub* kind looks like:
 553 ///
 554 /// 0-3  reserved
 555 /// 4-6  symbol kind
 556 /// 7    0 == global, 1 == static
 557 ///
 558 /// A gdb_index descriptor includes the above kind, shifted 24 bits up with the
 559 /// offset of the cu within the debug_info section stored in those 24 bits.
 560 struct PubIndexEntryDescriptor {
 561   GDBIndexEntryKind Kind;
 562   GDBIndexEntryLinkage Linkage;
 563   PubIndexEntryDescriptor(GDBIndexEntryKind Kind, GDBIndexEntryLinkage Linkage)
 564       : Kind(Kind), Linkage(Linkage) {}
 565   /* implicit */ PubIndexEntryDescriptor(GDBIndexEntryKind Kind)
 566       : Kind(Kind), Linkage(GIEL_EXTERNAL) {}
 567   explicit PubIndexEntryDescriptor(uint8_t Value)
 568       : Kind(
 569             static_cast<GDBIndexEntryKind>((Value & KIND_MASK) >> KIND_OFFSET)),
 570         Linkage(static_cast<GDBIndexEntryLinkage>((Value & LINKAGE_MASK) >>
 571                                                   LINKAGE_OFFSET)) {}
 572   uint8_t toBits() const {
 573     return Kind << KIND_OFFSET | Linkage << LINKAGE_OFFSET;
 574   }
 575
 576 private:
 577   enum {
 578     KIND_OFFSET = 4,
 579     KIND_MASK = 7 << KIND_OFFSET,
 580     LINKAGE_OFFSET = 7,
 581     LINKAGE_MASK = 1 << LINKAGE_OFFSET
 582   };
 583 };
 584
 585 template <typename Enum> struct EnumTraits : public std::false_type {};
 586
 587 template <> struct EnumTraits<Attribute> : public std::true_type {
 588   static constexpr char Type[3] = "AT";
 589   static constexpr StringRef (*StringFn)(unsigned) = &AttributeString;
 590 };
 591
 592 template <> struct EnumTraits<Form> : public std::true_type {
 593   static constexpr char Type[5] = "FORM";
 594   static constexpr StringRef (*StringFn)(unsigned) = &FormEncodingString;
 595 };
 596
 597 template <> struct EnumTraits<Index> : public std::true_type {
 598   static constexpr char Type[4] = "IDX";
 599   static constexpr StringRef (*StringFn)(unsigned) = &IndexString;
 600 };
 601
 602 template <> struct EnumTraits<Tag> : public std::true_type {
 603   static constexpr char Type[4] = "TAG";
 604   static constexpr StringRef (*StringFn)(unsigned) = &TagString;
 605 };
 606 } // End of namespace dwarf
 607
 608 /// Dwarf constants format_provider
 609 ///
 610 /// Specialization of the format_provider template for dwarf enums. Unlike the
 611 /// dumping functions above, these format unknown enumerator values as
 612 /// DW_TYPE_unknown_1234 (e.g. DW_TAG_unknown_ffff).
 613 template <typename Enum>
 614 struct format_provider<
 615     Enum, typename std::enable_if<dwarf::EnumTraits<Enum>::value>::type> {
 616   static void format(const Enum &E, raw_ostream &OS, StringRef Style) {
 617     StringRef Str = dwarf::EnumTraits<Enum>::StringFn(E);
 618     if (Str.empty()) {
 619       OS << "DW_" << dwarf::EnumTraits<Enum>::Type << "_unknown_"
 620          << llvm::format("%x", E);
 621     } else
 622       OS << Str;
 623   }
 624 };
 625 } // End of namespace llvm
 626
 627 #endif