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   // Special values for an initial length field.
  50   DW_LENGTH_lo_reserved = 0xfffffff0, // Lower bound of the reserved range.
  51   DW_LENGTH_DWARF64 = 0xffffffff,     // Indicator of 64-bit DWARF format.
  52   DW_LENGTH_hi_reserved = 0xffffffff, // Upper bound of the reserved range.
  53
  54   // Other constants.
  55   DWARF_VERSION = 4,       // Default dwarf version we output.
  56   DW_PUBTYPES_VERSION = 2, // Section version number for .debug_pubtypes.
  57   DW_PUBNAMES_VERSION = 2, // Section version number for .debug_pubnames.
  58   DW_ARANGES_VERSION = 2,  // Section version number for .debug_aranges.
  59   // Identifiers we use to distinguish vendor extensions.
  60   DWARF_VENDOR_DWARF = 0, // Defined in v2 or later of the DWARF standard.
  61   DWARF_VENDOR_APPLE = 1,
  62   DWARF_VENDOR_BORLAND = 2,
  63   DWARF_VENDOR_GNU = 3,
  64   DWARF_VENDOR_GOOGLE = 4,
  65   DWARF_VENDOR_LLVM = 5,
  66   DWARF_VENDOR_MIPS = 6
  67 };
  68
  69 /// Constants that define the DWARF format as 32 or 64 bit.
  70 enum DwarfFormat : uint8_t { DWARF32, DWARF64 };
  71
  72 /// Special ID values that distinguish a CIE from a FDE in DWARF CFI.
  73 /// Not inside an enum because a 64-bit value is needed.
  74 /// @{
  75 const uint32_t DW_CIE_ID = UINT32_MAX;
  76 const uint64_t DW64_CIE_ID = UINT64_MAX;
  77 /// @}
  78
  79 /// Identifier of an invalid DIE offset in the .debug_info section.
  80 const uint32_t DW_INVALID_OFFSET = UINT32_MAX;
  81
  82 enum Tag : uint16_t {
  83 #define HANDLE_DW_TAG(ID, NAME, VERSION, VENDOR, KIND) DW_TAG_##NAME = ID,
  84 #include "llvm/BinaryFormat/Dwarf.def"
  85   DW_TAG_lo_user = 0x4080,
  86   DW_TAG_hi_user = 0xffff,
  87   DW_TAG_user_base = 0x1000 ///< Recommended base for user tags.
  88 };
  89
  90 inline bool isType(Tag T) {
  91   switch (T) {
  92   default:
  93     return false;
  94 #define HANDLE_DW_TAG(ID, NAME, VERSION, VENDOR, KIND)                         \
  95   case DW_TAG_##NAME:                                                          \
  96     return (KIND == DW_KIND_TYPE);
  97 #include "llvm/BinaryFormat/Dwarf.def"
  98   }
  99 }
 100
 101 /// Attributes.
 102 enum Attribute : uint16_t {
 103 #define HANDLE_DW_AT(ID, NAME, VERSION, VENDOR) DW_AT_##NAME = ID,
 104 #include "llvm/BinaryFormat/Dwarf.def"
 105   DW_AT_lo_user = 0x2000,
 106   DW_AT_hi_user = 0x3fff,
 107 };
 108
 109 enum Form : uint16_t {
 110 #define HANDLE_DW_FORM(ID, NAME, VERSION, VENDOR) DW_FORM_##NAME = ID,
 111 #include "llvm/BinaryFormat/Dwarf.def"
 112   DW_FORM_lo_user = 0x1f00, ///< Not specified by DWARF.
 113 };
 114
 115 enum LocationAtom {
 116 #define HANDLE_DW_OP(ID, NAME, VERSION, VENDOR) DW_OP_##NAME = ID,
 117 #include "llvm/BinaryFormat/Dwarf.def"
 118   DW_OP_lo_user = 0xe0,
 119   DW_OP_hi_user = 0xff,
 120   DW_OP_LLVM_fragment = 0x1000,   ///< Only used in LLVM metadata.
 121   DW_OP_LLVM_convert = 0x1001,    ///< Only used in LLVM metadata.
 122   DW_OP_LLVM_tag_offset = 0x1002, ///< Only used in LLVM metadata.
 123 };
 124
 125 enum TypeKind : uint8_t {
 126 #define HANDLE_DW_ATE(ID, NAME, VERSION, VENDOR) DW_ATE_##NAME = ID,
 127 #include "llvm/BinaryFormat/Dwarf.def"
 128   DW_ATE_lo_user = 0x80,
 129   DW_ATE_hi_user = 0xff
 130 };
 131
 132 enum DecimalSignEncoding {
 133   // Decimal sign attribute values
 134   DW_DS_unsigned = 0x01,
 135   DW_DS_leading_overpunch = 0x02,
 136   DW_DS_trailing_overpunch = 0x03,
 137   DW_DS_leading_separate = 0x04,
 138   DW_DS_trailing_separate = 0x05
 139 };
 140
 141 enum EndianityEncoding {
 142   // Endianity attribute values
 143 #define HANDLE_DW_END(ID, NAME) DW_END_##NAME = ID,
 144 #include "llvm/BinaryFormat/Dwarf.def"
 145   DW_END_lo_user = 0x40,
 146   DW_END_hi_user = 0xff
 147 };
 148
 149 enum AccessAttribute {
 150   // Accessibility codes
 151   DW_ACCESS_public = 0x01,
 152   DW_ACCESS_protected = 0x02,
 153   DW_ACCESS_private = 0x03
 154 };
 155
 156 enum VisibilityAttribute {
 157   // Visibility codes
 158   DW_VIS_local = 0x01,
 159   DW_VIS_exported = 0x02,
 160   DW_VIS_qualified = 0x03
 161 };
 162
 163 enum VirtualityAttribute {
 164 #define HANDLE_DW_VIRTUALITY(ID, NAME) DW_VIRTUALITY_##NAME = ID,
 165 #include "llvm/BinaryFormat/Dwarf.def"
 166   DW_VIRTUALITY_max = 0x02
 167 };
 168
 169 enum DefaultedMemberAttribute {
 170 #define HANDLE_DW_DEFAULTED(ID, NAME) DW_DEFAULTED_##NAME = ID,
 171 #include "llvm/BinaryFormat/Dwarf.def"
 172   DW_DEFAULTED_max = 0x02
 173 };
 174
 175 enum SourceLanguage {
 176 #define HANDLE_DW_LANG(ID, NAME, LOWER_BOUND, VERSION, VENDOR)                 \
 177   DW_LANG_##NAME = ID,
 178 #include "llvm/BinaryFormat/Dwarf.def"
 179   DW_LANG_lo_user = 0x8000,
 180   DW_LANG_hi_user = 0xffff
 181 };
 182
 183 enum CaseSensitivity {
 184   // Identifier case codes
 185   DW_ID_case_sensitive = 0x00,
 186   DW_ID_up_case = 0x01,
 187   DW_ID_down_case = 0x02,
 188   DW_ID_case_insensitive = 0x03
 189 };
 190
 191 enum CallingConvention {
 192 // Calling convention codes
 193 #define HANDLE_DW_CC(ID, NAME) DW_CC_##NAME = ID,
 194 #include "llvm/BinaryFormat/Dwarf.def"
 195   DW_CC_lo_user = 0x40,
 196   DW_CC_hi_user = 0xff
 197 };
 198
 199 enum InlineAttribute {
 200   // Inline codes
 201   DW_INL_not_inlined = 0x00,
 202   DW_INL_inlined = 0x01,
 203   DW_INL_declared_not_inlined = 0x02,
 204   DW_INL_declared_inlined = 0x03
 205 };
 206
 207 enum ArrayDimensionOrdering {
 208   // Array ordering
 209   DW_ORD_row_major = 0x00,
 210   DW_ORD_col_major = 0x01
 211 };
 212
 213 enum DiscriminantList {
 214   // Discriminant descriptor values
 215   DW_DSC_label = 0x00,
 216   DW_DSC_range = 0x01
 217 };
 218
 219 /// Line Number Standard Opcode Encodings.
 220 enum LineNumberOps : uint8_t {
 221 #define HANDLE_DW_LNS(ID, NAME) DW_LNS_##NAME = ID,
 222 #include "llvm/BinaryFormat/Dwarf.def"
 223 };
 224
 225 /// Line Number Extended Opcode Encodings.
 226 enum LineNumberExtendedOps {
 227 #define HANDLE_DW_LNE(ID, NAME) DW_LNE_##NAME = ID,
 228 #include "llvm/BinaryFormat/Dwarf.def"
 229   DW_LNE_lo_user = 0x80,
 230   DW_LNE_hi_user = 0xff
 231 };
 232
 233 enum LineNumberEntryFormat {
 234 #define HANDLE_DW_LNCT(ID, NAME) DW_LNCT_##NAME = ID,
 235 #include "llvm/BinaryFormat/Dwarf.def"
 236   DW_LNCT_lo_user = 0x2000,
 237   DW_LNCT_hi_user = 0x3fff,
 238 };
 239
 240 enum MacinfoRecordType {
 241   // Macinfo Type Encodings
 242   DW_MACINFO_define = 0x01,
 243   DW_MACINFO_undef = 0x02,
 244   DW_MACINFO_start_file = 0x03,
 245   DW_MACINFO_end_file = 0x04,
 246   DW_MACINFO_vendor_ext = 0xff
 247 };
 248
 249 /// DWARF v5 macro information entry type encodings.
 250 enum MacroEntryType {
 251 #define HANDLE_DW_MACRO(ID, NAME) DW_MACRO_##NAME = ID,
 252 #include "llvm/BinaryFormat/Dwarf.def"
 253   DW_MACRO_lo_user = 0xe0,
 254   DW_MACRO_hi_user = 0xff
 255 };
 256
 257 /// DWARF v5 range list entry encoding values.
 258 enum RangeListEntries {
 259 #define HANDLE_DW_RLE(ID, NAME) DW_RLE_##NAME = ID,
 260 #include "llvm/BinaryFormat/Dwarf.def"
 261 };
 262
 263 /// Call frame instruction encodings.
 264 enum CallFrameInfo {
 265 #define HANDLE_DW_CFA(ID, NAME) DW_CFA_##NAME = ID,
 266 #define HANDLE_DW_CFA_PRED(ID, NAME, ARCH) DW_CFA_##NAME = ID,
 267 #include "llvm/BinaryFormat/Dwarf.def"
 268   DW_CFA_extended = 0x00,
 269
 270   DW_CFA_lo_user = 0x1c,
 271   DW_CFA_hi_user = 0x3f
 272 };
 273
 274 enum Constants {
 275   // Children flag
 276   DW_CHILDREN_no = 0x00,
 277   DW_CHILDREN_yes = 0x01,
 278
 279   DW_EH_PE_absptr = 0x00,
 280   DW_EH_PE_omit = 0xff,
 281   DW_EH_PE_uleb128 = 0x01,
 282   DW_EH_PE_udata2 = 0x02,
 283   DW_EH_PE_udata4 = 0x03,
 284   DW_EH_PE_udata8 = 0x04,
 285   DW_EH_PE_sleb128 = 0x09,
 286   DW_EH_PE_sdata2 = 0x0A,
 287   DW_EH_PE_sdata4 = 0x0B,
 288   DW_EH_PE_sdata8 = 0x0C,
 289   DW_EH_PE_signed = 0x08,
 290   DW_EH_PE_pcrel = 0x10,
 291   DW_EH_PE_textrel = 0x20,
 292   DW_EH_PE_datarel = 0x30,
 293   DW_EH_PE_funcrel = 0x40,
 294   DW_EH_PE_aligned = 0x50,
 295   DW_EH_PE_indirect = 0x80
 296 };
 297
 298 /// Constants for location lists in DWARF v5.
 299 enum LocationListEntry : unsigned char {
 300   DW_LLE_end_of_list = 0x00,
 301   DW_LLE_base_addressx = 0x01,
 302   DW_LLE_startx_endx = 0x02,
 303   DW_LLE_startx_length = 0x03,
 304   DW_LLE_offset_pair = 0x04,
 305   DW_LLE_default_location = 0x05,
 306   DW_LLE_base_address = 0x06,
 307   DW_LLE_start_end = 0x07,
 308   DW_LLE_start_length = 0x08
 309 };
 310
 311 /// Constants for the DW_APPLE_PROPERTY_attributes attribute.
 312 /// Keep this list in sync with clang's DeclSpec.h ObjCPropertyAttributeKind!
 313 enum ApplePropertyAttributes {
 314 #define HANDLE_DW_APPLE_PROPERTY(ID, NAME) DW_APPLE_PROPERTY_##NAME = ID,
 315 #include "llvm/BinaryFormat/Dwarf.def"
 316 };
 317
 318 /// Constants for unit types in DWARF v5.
 319 enum UnitType : unsigned char {
 320 #define HANDLE_DW_UT(ID, NAME) DW_UT_##NAME = ID,
 321 #include "llvm/BinaryFormat/Dwarf.def"
 322   DW_UT_lo_user = 0x80,
 323   DW_UT_hi_user = 0xff
 324 };
 325
 326 enum Index {
 327 #define HANDLE_DW_IDX(ID, NAME) DW_IDX_##NAME = ID,
 328 #include "llvm/BinaryFormat/Dwarf.def"
 329   DW_IDX_lo_user = 0x2000,
 330   DW_IDX_hi_user = 0x3fff
 331 };
 332
 333 inline bool isUnitType(uint8_t UnitType) {
 334   switch (UnitType) {
 335   case DW_UT_compile:
 336   case DW_UT_type:
 337   case DW_UT_partial:
 338   case DW_UT_skeleton:
 339   case DW_UT_split_compile:
 340   case DW_UT_split_type:
 341     return true;
 342   default:
 343     return false;
 344   }
 345 }
 346
 347 inline bool isUnitType(dwarf::Tag T) {
 348   switch (T) {
 349   case DW_TAG_compile_unit:
 350   case DW_TAG_type_unit:
 351   case DW_TAG_partial_unit:
 352   case DW_TAG_skeleton_unit:
 353     return true;
 354   default:
 355     return false;
 356   }
 357 }
 358
 359 // Constants for the DWARF v5 Accelerator Table Proposal
 360 enum AcceleratorTable {
 361   // Data layout descriptors.
 362   DW_ATOM_null = 0u,       ///  Marker as the end of a list of atoms.
 363   DW_ATOM_die_offset = 1u, // DIE offset in the debug_info section.
 364   DW_ATOM_cu_offset = 2u, // Offset of the compile unit header that contains the
 365                           // item in question.
 366   DW_ATOM_die_tag = 3u,   // A tag entry.
 367   DW_ATOM_type_flags = 4u, // Set of flags for a type.
 368
 369   DW_ATOM_type_type_flags = 5u, // Dsymutil type extension.
 370   DW_ATOM_qual_name_hash = 6u,  // Dsymutil qualified hash extension.
 371
 372   // DW_ATOM_type_flags values.
 373
 374   // Always set for C++, only set for ObjC if this is the @implementation for a
 375   // class.
 376   DW_FLAG_type_implementation = 2u,
 377
 378   // Hash functions.
 379
 380   // Daniel J. Bernstein hash.
 381   DW_hash_function_djb = 0u
 382 };
 383
 384 // Constants for the GNU pubnames/pubtypes extensions supporting gdb index.
 385 enum GDBIndexEntryKind {
 386   GIEK_NONE,
 387   GIEK_TYPE,
 388   GIEK_VARIABLE,
 389   GIEK_FUNCTION,
 390   GIEK_OTHER,
 391   GIEK_UNUSED5,
 392   GIEK_UNUSED6,
 393   GIEK_UNUSED7
 394 };
 395
 396 enum GDBIndexEntryLinkage { GIEL_EXTERNAL, GIEL_STATIC };
 397
 398 /// \defgroup DwarfConstantsDumping Dwarf constants dumping functions
 399 ///
 400 /// All these functions map their argument's value back to the
 401 /// corresponding enumerator name or return an empty StringRef if the value
 402 /// isn't known.
 403 ///
 404 /// @{
 405 StringRef TagString(unsigned Tag);
 406 StringRef ChildrenString(unsigned Children);
 407 StringRef AttributeString(unsigned Attribute);
 408 StringRef FormEncodingString(unsigned Encoding);
 409 StringRef OperationEncodingString(unsigned Encoding);
 410 StringRef AttributeEncodingString(unsigned Encoding);
 411 StringRef DecimalSignString(unsigned Sign);
 412 StringRef EndianityString(unsigned Endian);
 413 StringRef AccessibilityString(unsigned Access);
 414 StringRef VisibilityString(unsigned Visibility);
 415 StringRef VirtualityString(unsigned Virtuality);
 416 StringRef LanguageString(unsigned Language);
 417 StringRef CaseString(unsigned Case);
 418 StringRef ConventionString(unsigned Convention);
 419 StringRef InlineCodeString(unsigned Code);
 420 StringRef ArrayOrderString(unsigned Order);
 421 StringRef LNStandardString(unsigned Standard);
 422 StringRef LNExtendedString(unsigned Encoding);
 423 StringRef MacinfoString(unsigned Encoding);
 424 StringRef RangeListEncodingString(unsigned Encoding);
 425 StringRef CallFrameString(unsigned Encoding, Triple::ArchType Arch);
 426 StringRef ApplePropertyString(unsigned);
 427 StringRef UnitTypeString(unsigned);
 428 StringRef AtomTypeString(unsigned Atom);
 429 StringRef GDBIndexEntryKindString(GDBIndexEntryKind Kind);
 430 StringRef GDBIndexEntryLinkageString(GDBIndexEntryLinkage Linkage);
 431 StringRef IndexString(unsigned Idx);
 432 /// @}
 433
 434 /// \defgroup DwarfConstantsParsing Dwarf constants parsing functions
 435 ///
 436 /// These functions map their strings back to the corresponding enumeration
 437 /// value or return 0 if there is none, except for these exceptions:
 438 ///
 439 /// \li \a getTag() returns \a DW_TAG_invalid on invalid input.
 440 /// \li \a getVirtuality() returns \a DW_VIRTUALITY_invalid on invalid input.
 441 /// \li \a getMacinfo() returns \a DW_MACINFO_invalid on invalid input.
 442 ///
 443 /// @{
 444 unsigned getTag(StringRef TagString);
 445 unsigned getOperationEncoding(StringRef OperationEncodingString);
 446 unsigned getVirtuality(StringRef VirtualityString);
 447 unsigned getLanguage(StringRef LanguageString);
 448 unsigned getCallingConvention(StringRef LanguageString);
 449 unsigned getAttributeEncoding(StringRef EncodingString);
 450 unsigned getMacinfo(StringRef MacinfoString);
 451 /// @}
 452
 453 /// \defgroup DwarfConstantsVersioning Dwarf version for constants
 454 ///
 455 /// For constants defined by DWARF, returns the DWARF version when the constant
 456 /// was first defined. For vendor extensions, if there is a version-related
 457 /// policy for when to emit it, returns a version number for that policy.
 458 /// Otherwise returns 0.
 459 ///
 460 /// @{
 461 unsigned TagVersion(Tag T);
 462 unsigned AttributeVersion(Attribute A);
 463 unsigned FormVersion(Form F);
 464 unsigned OperationVersion(LocationAtom O);
 465 unsigned AttributeEncodingVersion(TypeKind E);
 466 unsigned LanguageVersion(SourceLanguage L);
 467 /// @}
 468
 469 /// \defgroup DwarfConstantsVendor Dwarf "vendor" for constants
 470 ///
 471 /// These functions return an identifier describing "who" defined the constant,
 472 /// either the DWARF standard itself or the vendor who defined the extension.
 473 ///
 474 /// @{
 475 unsigned TagVendor(Tag T);
 476 unsigned AttributeVendor(Attribute A);
 477 unsigned FormVendor(Form F);
 478 unsigned OperationVendor(LocationAtom O);
 479 unsigned AttributeEncodingVendor(TypeKind E);
 480 unsigned LanguageVendor(SourceLanguage L);
 481 /// @}
 482
 483 Optional<unsigned> LanguageLowerBound(SourceLanguage L);
 484
 485 /// A helper struct providing information about the byte size of DW_FORM
 486 /// values that vary in size depending on the DWARF version, address byte
 487 /// size, or DWARF32/DWARF64.
 488 struct FormParams {
 489   uint16_t Version;
 490   uint8_t AddrSize;
 491   DwarfFormat Format;
 492
 493   /// The definition of the size of form DW_FORM_ref_addr depends on the
 494   /// version. In DWARF v2 it's the size of an address; after that, it's the
 495   /// size of a reference.
 496   uint8_t getRefAddrByteSize() const {
 497     if (Version == 2)
 498       return AddrSize;
 499     return getDwarfOffsetByteSize();
 500   }
 501
 502   /// The size of a reference is determined by the DWARF 32/64-bit format.
 503   uint8_t getDwarfOffsetByteSize() const {
 504     switch (Format) {
 505     case DwarfFormat::DWARF32:
 506       return 4;
 507     case DwarfFormat::DWARF64:
 508       return 8;
 509     }
 510     llvm_unreachable("Invalid Format value");
 511   }
 512
 513   explicit operator bool() const { return Version && AddrSize; }
 514 };
 515
 516 /// Get the byte size of the unit length field depending on the DWARF format.
 517 inline uint8_t getUnitLengthFieldByteSize(DwarfFormat Format) {
 518   switch (Format) {
 519   case DwarfFormat::DWARF32:
 520     return 4;
 521   case DwarfFormat::DWARF64:
 522     return 12;
 523   }
 524   llvm_unreachable("Invalid Format value");
 525 }
 526
 527 /// Get the fixed byte size for a given form.
 528 ///
 529 /// If the form has a fixed byte size, then an Optional with a value will be
 530 /// returned. If the form is always encoded using a variable length storage
 531 /// format (ULEB or SLEB numbers or blocks) then None will be returned.
 532 ///
 533 /// \param Form DWARF form to get the fixed byte size for.
 534 /// \param Params DWARF parameters to help interpret forms.
 535 /// \returns Optional<uint8_t> value with the fixed byte size or None if
 536 /// \p Form doesn't have a fixed byte size.
 537 Optional<uint8_t> getFixedFormByteSize(dwarf::Form Form, FormParams Params);
 538
 539 /// Tells whether the specified form is defined in the specified version,
 540 /// or is an extension if extensions are allowed.
 541 bool isValidFormForVersion(Form F, unsigned Version, bool ExtensionsOk = true);
 542
 543 /// Returns the symbolic string representing Val when used as a value
 544 /// for attribute Attr.
 545 StringRef AttributeValueString(uint16_t Attr, unsigned Val);
 546
 547 /// Returns the symbolic string representing Val when used as a value
 548 /// for atom Atom.
 549 StringRef AtomValueString(uint16_t Atom, unsigned Val);
 550
 551 /// Describes an entry of the various gnu_pub* debug sections.
 552 ///
 553 /// The gnu_pub* kind looks like:
 554 ///
 555 /// 0-3  reserved
 556 /// 4-6  symbol kind
 557 /// 7    0 == global, 1 == static
 558 ///
 559 /// A gdb_index descriptor includes the above kind, shifted 24 bits up with the
 560 /// offset of the cu within the debug_info section stored in those 24 bits.
 561 struct PubIndexEntryDescriptor {
 562   GDBIndexEntryKind Kind;
 563   GDBIndexEntryLinkage Linkage;
 564   PubIndexEntryDescriptor(GDBIndexEntryKind Kind, GDBIndexEntryLinkage Linkage)
 565       : Kind(Kind), Linkage(Linkage) {}
 566   /* implicit */ PubIndexEntryDescriptor(GDBIndexEntryKind Kind)
 567       : Kind(Kind), Linkage(GIEL_EXTERNAL) {}
 568   explicit PubIndexEntryDescriptor(uint8_t Value)
 569       : Kind(
 570             static_cast<GDBIndexEntryKind>((Value & KIND_MASK) >> KIND_OFFSET)),
 571         Linkage(static_cast<GDBIndexEntryLinkage>((Value & LINKAGE_MASK) >>
 572                                                   LINKAGE_OFFSET)) {}
 573   uint8_t toBits() const {
 574     return Kind << KIND_OFFSET | Linkage << LINKAGE_OFFSET;
 575   }
 576
 577 private:
 578   enum {
 579     KIND_OFFSET = 4,
 580     KIND_MASK = 7 << KIND_OFFSET,
 581     LINKAGE_OFFSET = 7,
 582     LINKAGE_MASK = 1 << LINKAGE_OFFSET
 583   };
 584 };
 585
 586 template <typename Enum> struct EnumTraits : public std::false_type {};
 587
 588 template <> struct EnumTraits<Attribute> : public std::true_type {
 589   static constexpr char Type[3] = "AT";
 590   static constexpr StringRef (*StringFn)(unsigned) = &AttributeString;
 591 };
 592
 593 template <> struct EnumTraits<Form> : public std::true_type {
 594   static constexpr char Type[5] = "FORM";
 595   static constexpr StringRef (*StringFn)(unsigned) = &FormEncodingString;
 596 };
 597
 598 template <> struct EnumTraits<Index> : public std::true_type {
 599   static constexpr char Type[4] = "IDX";
 600   static constexpr StringRef (*StringFn)(unsigned) = &IndexString;
 601 };
 602
 603 template <> struct EnumTraits<Tag> : public std::true_type {
 604   static constexpr char Type[4] = "TAG";
 605   static constexpr StringRef (*StringFn)(unsigned) = &TagString;
 606 };
 607 } // End of namespace dwarf
 608
 609 /// Dwarf constants format_provider
 610 ///
 611 /// Specialization of the format_provider template for dwarf enums. Unlike the
 612 /// dumping functions above, these format unknown enumerator values as
 613 /// DW_TYPE_unknown_1234 (e.g. DW_TAG_unknown_ffff).
 614 template <typename Enum>
 615 struct format_provider<
 616     Enum, typename std::enable_if<dwarf::EnumTraits<Enum>::value>::type> {
 617   static void format(const Enum &E, raw_ostream &OS, StringRef Style) {
 618     StringRef Str = dwarf::EnumTraits<Enum>::StringFn(E);
 619     if (Str.empty()) {
 620       OS << "DW_" << dwarf::EnumTraits<Enum>::Type << "_unknown_"
 621          << llvm::format("%x", E);
 622     } else
 623       OS << Str;
 624   }
 625 };
 626 } // End of namespace llvm
 627
 628 #endif