src/llvm/include/llvm/MC/MCAsmInfo.h

   1 //===-- llvm/MC/MCAsmInfo.h - Asm info --------------------------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file contains a class to be used as the basis for target specific
  11 // asm writers.  This class primarily takes care of global printing constants,
  12 // which are used in very similar ways across all targets.
  13 //
  14 //===----------------------------------------------------------------------===//
  15
  16 #ifndef LLVM_MC_MCASMINFO_H
  17 #define LLVM_MC_MCASMINFO_H
  18
  19 #include "llvm/MC/MCDirectives.h"
  20 #include "llvm/MC/MCDwarf.h"
  21 #include "llvm/MC/MachineLocation.h"
  22 #include <cassert>
  23 #include <vector>
  24
  25 namespace llvm {
  26 class MCExpr;
  27 class MCSection;
  28 class MCStreamer;
  29 class MCSymbol;
  30 class MCContext;
  31
  32 namespace WinEH {
  33 enum class EncodingType {
  34   Invalid, /// Invalid
  35   Alpha,   /// Windows Alpha
  36   Alpha64, /// Windows AXP64
  37   ARM,     /// Windows NT (Windows on ARM)
  38   CE,      /// Windows CE ARM, PowerPC, SH3, SH4
  39   Itanium, /// Windows x64, Windows Itanium (IA-64)
  40   MIPS = Alpha,
  41 };
  42 }
  43
  44 enum class ExceptionHandling {
  45   None,         /// No exception support
  46   DwarfCFI,     /// DWARF-like instruction based exceptions
  47   SjLj,         /// setjmp/longjmp based exceptions
  48   ARM,          /// ARM EHABI
  49   ItaniumWinEH, /// Itanium EH built on Windows unwind info (.pdata and .xdata)
  50   MSVC,         /// MSVC compatible exception handling
  51 };
  52
  53 namespace LCOMM {
  54 enum LCOMMType { NoAlignment, ByteAlignment, Log2Alignment };
  55 }
  56
  57 /// This class is intended to be used as a base class for asm
  58 /// properties and features specific to the target.
  59 class MCAsmInfo {
  60 protected:
  61   //===------------------------------------------------------------------===//
  62   // Properties to be set by the target writer, used to configure asm printer.
  63   //
  64
  65   /// Pointer size in bytes.  Default is 4.
  66   unsigned PointerSize;
  67
  68   /// Size of the stack slot reserved for callee-saved registers, in bytes.
  69   /// Default is same as pointer size.
  70   unsigned CalleeSaveStackSlotSize;
  71
  72   /// True if target is little endian.  Default is true.
  73   bool IsLittleEndian;
  74
  75   /// True if target stack grow up.  Default is false.
  76   bool StackGrowsUp;
  77
  78   /// True if this target has the MachO .subsections_via_symbols directive.
  79   /// Default is false.
  80   bool HasSubsectionsViaSymbols;
  81
  82   /// True if this is a MachO target that supports the macho-specific .zerofill
  83   /// directive for emitting BSS Symbols.  Default is false.
  84   bool HasMachoZeroFillDirective;
  85
  86   /// True if this is a MachO target that supports the macho-specific .tbss
  87   /// directive for emitting thread local BSS Symbols.  Default is false.
  88   bool HasMachoTBSSDirective;
  89
  90   /// True if the compiler should emit a ".reference .constructors_used" or
  91   /// ".reference .destructors_used" directive after the static ctor/dtor
  92   /// list.  This directive is only emitted in Static relocation model.  Default
  93   /// is false.
  94   bool HasStaticCtorDtorReferenceInStaticMode;
  95
  96   /// This is the maximum possible length of an instruction, which is needed to
  97   /// compute the size of an inline asm.  Defaults to 4.
  98   unsigned MaxInstLength;
  99
 100   /// Every possible instruction length is a multiple of this value.  Factored
 101   /// out in .debug_frame and .debug_line.  Defaults to 1.
 102   unsigned MinInstAlignment;
 103
 104   /// The '$' token, when not referencing an identifier or constant, refers to
 105   /// the current PC.  Defaults to false.
 106   bool DollarIsPC;
 107
 108   /// This string, if specified, is used to separate instructions from each
 109   /// other when on the same line.  Defaults to ';'
 110   const char *SeparatorString;
 111
 112   /// This indicates the comment character used by the assembler.  Defaults to
 113   /// "#"
 114   const char *CommentString;
 115
 116   /// This is appended to emitted labels.  Defaults to ":"
 117   const char *LabelSuffix;
 118
 119   // Print the EH begin symbol with an assignment. Defaults to false.
 120   bool UseAssignmentForEHBegin;
 121
 122   /// This prefix is used for globals like constant pool entries that are
 123   /// completely private to the .s file and should not have names in the .o
 124   /// file.  Defaults to "L"
 125   const char *PrivateGlobalPrefix;
 126
 127   /// This prefix is used for labels for basic blocks. Defaults to the same as
 128   /// PrivateGlobalPrefix.
 129   const char *PrivateLabelPrefix;
 130
 131   /// This prefix is used for symbols that should be passed through the
 132   /// assembler but be removed by the linker.  This is 'l' on Darwin, currently
 133   /// used for some ObjC metadata.  The default of "" meast that for this system
 134   /// a plain private symbol should be used.  Defaults to "".
 135   const char *LinkerPrivateGlobalPrefix;
 136
 137   /// If these are nonempty, they contain a directive to emit before and after
 138   /// an inline assembly statement.  Defaults to "#APP\n", "#NO_APP\n"
 139   const char *InlineAsmStart;
 140   const char *InlineAsmEnd;
 141
 142   /// These are assembly directives that tells the assembler to interpret the
 143   /// following instructions differently.  Defaults to ".code16", ".code32",
 144   /// ".code64".
 145   const char *Code16Directive;
 146   const char *Code32Directive;
 147   const char *Code64Directive;
 148
 149   /// Which dialect of an assembler variant to use.  Defaults to 0
 150   unsigned AssemblerDialect;
 151
 152   /// This is true if the assembler allows @ characters in symbol names.
 153   /// Defaults to false.
 154   bool AllowAtInName;
 155
 156   /// This is true if data region markers should be printed as
 157   /// ".data_region/.end_data_region" directives. If false, use "$d/$a" labels
 158   /// instead.
 159   bool UseDataRegionDirectives;
 160
 161   //===--- Data Emission Directives -------------------------------------===//
 162
 163   /// This should be set to the directive used to get some number of zero bytes
 164   /// emitted to the current section.  Common cases are "\t.zero\t" and
 165   /// "\t.space\t".  If this is set to null, the Data*bitsDirective's will be
 166   /// used to emit zero bytes.  Defaults to "\t.zero\t"
 167   const char *ZeroDirective;
 168
 169   /// This directive allows emission of an ascii string with the standard C
 170   /// escape characters embedded into it.  Defaults to "\t.ascii\t"
 171   const char *AsciiDirective;
 172
 173   /// If not null, this allows for special handling of zero terminated strings
 174   /// on this target.  This is commonly supported as ".asciz".  If a target
 175   /// doesn't support this, it can be set to null.  Defaults to "\t.asciz\t"
 176   const char *AscizDirective;
 177
 178   /// These directives are used to output some unit of integer data to the
 179   /// current section.  If a data directive is set to null, smaller data
 180   /// directives will be used to emit the large sizes.  Defaults to "\t.byte\t",
 181   /// "\t.short\t", "\t.long\t", "\t.quad\t"
 182   const char *Data8bitsDirective;
 183   const char *Data16bitsDirective;
 184   const char *Data32bitsDirective;
 185   const char *Data64bitsDirective;
 186
 187   /// If non-null, a directive that is used to emit a word which should be
 188   /// relocated as a 64-bit GP-relative offset, e.g. .gpdword on Mips.  Defaults
 189   /// to NULL.
 190   const char *GPRel64Directive;
 191
 192   /// If non-null, a directive that is used to emit a word which should be
 193   /// relocated as a 32-bit GP-relative offset, e.g. .gpword on Mips or .gprel32
 194   /// on Alpha.  Defaults to NULL.
 195   const char *GPRel32Directive;
 196
 197   /// This is true if this target uses "Sun Style" syntax for section switching
 198   /// ("#alloc,#write" etc) instead of the normal ELF syntax (,"a,w") in
 199   /// .section directives.  Defaults to false.
 200   bool SunStyleELFSectionSwitchSyntax;
 201
 202   /// This is true if this target uses ELF '.section' directive before the
 203   /// '.bss' one. It's used for PPC/Linux which doesn't support the '.bss'
 204   /// directive only.  Defaults to false.
 205   bool UsesELFSectionDirectiveForBSS;
 206
 207   bool NeedsDwarfSectionOffsetDirective;
 208
 209   //===--- Alignment Information ----------------------------------------===//
 210
 211   /// If this is true (the default) then the asmprinter emits ".align N"
 212   /// directives, where N is the number of bytes to align to.  Otherwise, it
 213   /// emits ".align log2(N)", e.g. 3 to align to an 8 byte boundary.  Defaults
 214   /// to true.
 215   bool AlignmentIsInBytes;
 216
 217   /// If non-zero, this is used to fill the executable space created as the
 218   /// result of a alignment directive.  Defaults to 0
 219   unsigned TextAlignFillValue;
 220
 221   //===--- Global Variable Emission Directives --------------------------===//
 222
 223   /// This is the directive used to declare a global entity. Defaults to
 224   /// ".globl".
 225   const char *GlobalDirective;
 226
 227   /// True if the expression
 228   ///   .long f - g
 229   /// uses an relocation but it can be supressed by writting
 230   ///   a = f - g
 231   ///   .long a
 232   bool SetDirectiveSuppressesReloc;
 233
 234   /// False if the assembler requires that we use
 235   /// \code
 236   ///   Lc = a - b
 237   ///   .long Lc
 238   /// \endcode
 239   //
 240   /// instead of
 241   //
 242   /// \code
 243   ///   .long a - b
 244   /// \endcode
 245   ///
 246   ///  Defaults to true.
 247   bool HasAggressiveSymbolFolding;
 248
 249   /// True is .comm's and .lcomms optional alignment is to be specified in bytes
 250   /// instead of log2(n).  Defaults to true.
 251   bool COMMDirectiveAlignmentIsInBytes;
 252
 253   /// Describes if the .lcomm directive for the target supports an alignment
 254   /// argument and how it is interpreted.  Defaults to NoAlignment.
 255   LCOMM::LCOMMType LCOMMDirectiveAlignmentType;
 256
 257   /// True if the target has .type and .size directives, this is true for most
 258   /// ELF targets.  Defaults to true.
 259   bool HasDotTypeDotSizeDirective;
 260
 261   /// True if the target has a single parameter .file directive, this is true
 262   /// for ELF targets.  Defaults to true.
 263   bool HasSingleParameterDotFile;
 264
 265   /// True if the target has a .ident directive, this is true for ELF targets.
 266   /// Defaults to false.
 267   bool HasIdentDirective;
 268
 269   /// True if this target supports the MachO .no_dead_strip directive.  Defaults
 270   /// to false.
 271   bool HasNoDeadStrip;
 272
 273   /// Used to declare a global as being a weak symbol. Defaults to ".weak".
 274   const char *WeakDirective;
 275
 276   /// This directive, if non-null, is used to declare a global as being a weak
 277   /// undefined symbol.  Defaults to NULL.
 278   const char *WeakRefDirective;
 279
 280   /// True if we have a directive to declare a global as being a weak defined
 281   /// symbol.  Defaults to false.
 282   bool HasWeakDefDirective;
 283
 284   /// True if we have a directive to declare a global as being a weak defined
 285   /// symbol that can be hidden (unexported).  Defaults to false.
 286   bool HasWeakDefCanBeHiddenDirective;
 287
 288   /// True if we have a .linkonce directive.  This is used on cygwin/mingw.
 289   /// Defaults to false.
 290   bool HasLinkOnceDirective;
 291
 292   /// This attribute, if not MCSA_Invalid, is used to declare a symbol as having
 293   /// hidden visibility.  Defaults to MCSA_Hidden.
 294   MCSymbolAttr HiddenVisibilityAttr;
 295
 296   /// This attribute, if not MCSA_Invalid, is used to declare an undefined
 297   /// symbol as having hidden visibility. Defaults to MCSA_Hidden.
 298   MCSymbolAttr HiddenDeclarationVisibilityAttr;
 299
 300   /// This attribute, if not MCSA_Invalid, is used to declare a symbol as having
 301   /// protected visibility.  Defaults to MCSA_Protected
 302   MCSymbolAttr ProtectedVisibilityAttr;
 303
 304   //===--- Dwarf Emission Directives -----------------------------------===//
 305
 306   /// True if target supports emission of debugging information.  Defaults to
 307   /// false.
 308   bool SupportsDebugInformation;
 309
 310   /// Exception handling format for the target.  Defaults to None.
 311   ExceptionHandling ExceptionsType;
 312
 313   /// Windows exception handling data (.pdata) encoding.  Defaults to Invalid.
 314   WinEH::EncodingType WinEHEncodingType;
 315
 316   /// True if Dwarf2 output generally uses relocations for references to other
 317   /// .debug_* sections.
 318   bool DwarfUsesRelocationsAcrossSections;
 319
 320   /// True if DWARF FDE symbol reference relocations should be replaced by an
 321   /// absolute difference.
 322   bool DwarfFDESymbolsUseAbsDiff;
 323
 324   /// True if dwarf register numbers are printed instead of symbolic register
 325   /// names in .cfi_* directives.  Defaults to false.
 326   bool DwarfRegNumForCFI;
 327
 328   /// True if target uses parens to indicate the symbol variant instead of @.
 329   /// For example, foo(plt) instead of foo@plt.  Defaults to false.
 330   bool UseParensForSymbolVariant;
 331
 332   //===--- Prologue State ----------------------------------------------===//
 333
 334   std::vector<MCCFIInstruction> InitialFrameState;
 335
 336   //===--- Integrated Assembler State ----------------------------------===//
 337
 338   /// Should we use the integrated assembler?
 339   /// The integrated assembler should be enabled by default (by the
 340   /// constructors) when failing to parse a valid piece of assembly (inline
 341   /// or otherwise) is considered a bug. It may then be overridden after
 342   /// construction (see LLVMTargetMachine::initAsmInfo()).
 343   bool UseIntegratedAssembler;
 344
 345   /// Compress DWARF debug sections. Defaults to false.
 346   bool CompressDebugSections;
 347
 348 public:
 349   explicit MCAsmInfo();
 350   virtual ~MCAsmInfo();
 351
 352   /// Get the pointer size in bytes.
 353   unsigned getPointerSize() const { return PointerSize; }
 354
 355   /// Get the callee-saved register stack slot
 356   /// size in bytes.
 357   unsigned getCalleeSaveStackSlotSize() const {
 358     return CalleeSaveStackSlotSize;
 359   }
 360
 361   /// True if the target is little endian.
 362   bool isLittleEndian() const { return IsLittleEndian; }
 363
 364   /// True if target stack grow up.
 365   bool isStackGrowthDirectionUp() const { return StackGrowsUp; }
 366
 367   bool hasSubsectionsViaSymbols() const { return HasSubsectionsViaSymbols; }
 368
 369   // Data directive accessors.
 370
 371   const char *getData8bitsDirective() const { return Data8bitsDirective; }
 372   const char *getData16bitsDirective() const { return Data16bitsDirective; }
 373   const char *getData32bitsDirective() const { return Data32bitsDirective; }
 374   const char *getData64bitsDirective() const { return Data64bitsDirective; }
 375   const char *getGPRel64Directive() const { return GPRel64Directive; }
 376   const char *getGPRel32Directive() const { return GPRel32Directive; }
 377
 378   /// Targets can implement this method to specify a section to switch to if the
 379   /// translation unit doesn't have any trampolines that require an executable
 380   /// stack.
 381   virtual const MCSection *getNonexecutableStackSection(MCContext &Ctx) const {
 382     return nullptr;
 383   }
 384
 385   /// \brief True if the section is atomized using the symbols in it.
 386   /// This is false if the section is not atomized at all (most ELF sections) or
 387   /// if it is atomized based on its contents (MachO' __TEXT,__cstring for
 388   /// example).
 389   virtual bool isSectionAtomizableBySymbols(const MCSection &Section) const;
 390
 391   virtual const MCExpr *getExprForPersonalitySymbol(const MCSymbol *Sym,
 392                                                     unsigned Encoding,
 393                                                     MCStreamer &Streamer) const;
 394
 395   virtual const MCExpr *getExprForFDESymbol(const MCSymbol *Sym,
 396                                             unsigned Encoding,
 397                                             MCStreamer &Streamer) const;
 398
 399   bool usesSunStyleELFSectionSwitchSyntax() const {
 400     return SunStyleELFSectionSwitchSyntax;
 401   }
 402
 403   bool usesELFSectionDirectiveForBSS() const {
 404     return UsesELFSectionDirectiveForBSS;
 405   }
 406
 407   bool needsDwarfSectionOffsetDirective() const {
 408     return NeedsDwarfSectionOffsetDirective;
 409   }
 410
 411   // Accessors.
 412
 413   bool hasMachoZeroFillDirective() const { return HasMachoZeroFillDirective; }
 414   bool hasMachoTBSSDirective() const { return HasMachoTBSSDirective; }
 415   bool hasStaticCtorDtorReferenceInStaticMode() const {
 416     return HasStaticCtorDtorReferenceInStaticMode;
 417   }
 418   unsigned getMaxInstLength() const { return MaxInstLength; }
 419   unsigned getMinInstAlignment() const { return MinInstAlignment; }
 420   bool getDollarIsPC() const { return DollarIsPC; }
 421   const char *getSeparatorString() const { return SeparatorString; }
 422
 423   /// This indicates the column (zero-based) at which asm comments should be
 424   /// printed.
 425   unsigned getCommentColumn() const { return 40; }
 426
 427   const char *getCommentString() const { return CommentString; }
 428   const char *getLabelSuffix() const { return LabelSuffix; }
 429
 430   bool useAssignmentForEHBegin() const { return UseAssignmentForEHBegin; }
 431   const char *getPrivateGlobalPrefix() const { return PrivateGlobalPrefix; }
 432   const char *getPrivateLabelPrefix() const { return PrivateLabelPrefix; }
 433   bool hasLinkerPrivateGlobalPrefix() const {
 434     return LinkerPrivateGlobalPrefix[0] != '\0';
 435   }
 436   const char *getLinkerPrivateGlobalPrefix() const {
 437     if (hasLinkerPrivateGlobalPrefix())
 438       return LinkerPrivateGlobalPrefix;
 439     return getPrivateGlobalPrefix();
 440   }
 441   const char *getInlineAsmStart() const { return InlineAsmStart; }
 442   const char *getInlineAsmEnd() const { return InlineAsmEnd; }
 443   const char *getCode16Directive() const { return Code16Directive; }
 444   const char *getCode32Directive() const { return Code32Directive; }
 445   const char *getCode64Directive() const { return Code64Directive; }
 446   unsigned getAssemblerDialect() const { return AssemblerDialect; }
 447   bool doesAllowAtInName() const { return AllowAtInName; }
 448   bool doesSupportDataRegionDirectives() const {
 449     return UseDataRegionDirectives;
 450   }
 451   const char *getZeroDirective() const { return ZeroDirective; }
 452   const char *getAsciiDirective() const { return AsciiDirective; }
 453   const char *getAscizDirective() const { return AscizDirective; }
 454   bool getAlignmentIsInBytes() const { return AlignmentIsInBytes; }
 455   unsigned getTextAlignFillValue() const { return TextAlignFillValue; }
 456   const char *getGlobalDirective() const { return GlobalDirective; }
 457   bool doesSetDirectiveSuppressesReloc() const {
 458     return SetDirectiveSuppressesReloc;
 459   }
 460   bool hasAggressiveSymbolFolding() const { return HasAggressiveSymbolFolding; }
 461   bool getCOMMDirectiveAlignmentIsInBytes() const {
 462     return COMMDirectiveAlignmentIsInBytes;
 463   }
 464   LCOMM::LCOMMType getLCOMMDirectiveAlignmentType() const {
 465     return LCOMMDirectiveAlignmentType;
 466   }
 467   bool hasDotTypeDotSizeDirective() const { return HasDotTypeDotSizeDirective; }
 468   bool hasSingleParameterDotFile() const { return HasSingleParameterDotFile; }
 469   bool hasIdentDirective() const { return HasIdentDirective; }
 470   bool hasNoDeadStrip() const { return HasNoDeadStrip; }
 471   const char *getWeakDirective() const { return WeakDirective; }
 472   const char *getWeakRefDirective() const { return WeakRefDirective; }
 473   bool hasWeakDefDirective() const { return HasWeakDefDirective; }
 474   bool hasWeakDefCanBeHiddenDirective() const {
 475     return HasWeakDefCanBeHiddenDirective;
 476   }
 477   bool hasLinkOnceDirective() const { return HasLinkOnceDirective; }
 478
 479   MCSymbolAttr getHiddenVisibilityAttr() const { return HiddenVisibilityAttr; }
 480   MCSymbolAttr getHiddenDeclarationVisibilityAttr() const {
 481     return HiddenDeclarationVisibilityAttr;
 482   }
 483   MCSymbolAttr getProtectedVisibilityAttr() const {
 484     return ProtectedVisibilityAttr;
 485   }
 486   bool doesSupportDebugInformation() const { return SupportsDebugInformation; }
 487   bool doesSupportExceptionHandling() const {
 488     return ExceptionsType != ExceptionHandling::None;
 489   }
 490   ExceptionHandling getExceptionHandlingType() const { return ExceptionsType; }
 491   WinEH::EncodingType getWinEHEncodingType() const { return WinEHEncodingType; }
 492
 493   /// Return true if the exception handling type uses the language-specific data
 494   /// area (LSDA) format specified by the Itanium C++ ABI.
 495   bool usesItaniumLSDAForExceptions() const {
 496     return (ExceptionsType == ExceptionHandling::DwarfCFI ||
 497             ExceptionsType == ExceptionHandling::ARM ||
 498             // This Windows EH type uses the Itanium LSDA encoding.
 499             ExceptionsType == ExceptionHandling::ItaniumWinEH);
 500   }
 501
 502   bool usesWindowsCFI() const {
 503     return ExceptionsType == ExceptionHandling::ItaniumWinEH ||
 504            ExceptionsType == ExceptionHandling::MSVC;
 505   }
 506
 507   bool doesDwarfUseRelocationsAcrossSections() const {
 508     return DwarfUsesRelocationsAcrossSections;
 509   }
 510   bool doDwarfFDESymbolsUseAbsDiff() const { return DwarfFDESymbolsUseAbsDiff; }
 511   bool useDwarfRegNumForCFI() const { return DwarfRegNumForCFI; }
 512   bool useParensForSymbolVariant() const { return UseParensForSymbolVariant; }
 513
 514   void addInitialFrameState(const MCCFIInstruction &Inst) {
 515     InitialFrameState.push_back(Inst);
 516   }
 517
 518   const std::vector<MCCFIInstruction> &getInitialFrameState() const {
 519     return InitialFrameState;
 520   }
 521
 522   /// Return true if assembly (inline or otherwise) should be parsed.
 523   bool useIntegratedAssembler() const { return UseIntegratedAssembler; }
 524
 525   /// Set whether assembly (inline or otherwise) should be parsed.
 526   virtual void setUseIntegratedAssembler(bool Value) {
 527     UseIntegratedAssembler = Value;
 528   }
 529
 530   bool compressDebugSections() const { return CompressDebugSections; }
 531
 532   void setCompressDebugSections(bool CompressDebugSections) {
 533     this->CompressDebugSections = CompressDebugSections;
 534   }
 535 };
 536 }
 537
 538 #endif