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      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_TARGET_ASM_INFO_H
     17 #define LLVM_TARGET_ASM_INFO_H
     18 
     19 #include "llvm/MC/MachineLocation.h"
     20 #include "llvm/MC/MCDirectives.h"
     21 #include <cassert>
     22 #include <vector>
     23 
     24 namespace llvm {
     25   class MCExpr;
     26   class MCSection;
     27   class MCStreamer;
     28   class MCSymbol;
     29   class MCContext;
     30 
     31   namespace ExceptionHandling {
     32     enum ExceptionsType { None, DwarfCFI, SjLj, ARM, Win64 };
     33   }
     34 
     35   /// MCAsmInfo - This class is intended to be used as a base class for asm
     36   /// properties and features specific to the target.
     37   class MCAsmInfo {
     38   protected:
     39     //===------------------------------------------------------------------===//
     40     // Properties to be set by the target writer, used to configure asm printer.
     41     //
     42 
     43     /// PointerSize - Pointer size in bytes.
     44     ///               Default is 4.
     45     unsigned PointerSize;
     46 
     47     /// IsLittleEndian - True if target is little endian.
     48     ///                  Default is true.
     49     bool IsLittleEndian;
     50 
     51     /// StackGrowsUp - True if target stack grow up.
     52     ///                Default is false.
     53     bool StackGrowsUp;
     54 
     55     /// HasSubsectionsViaSymbols - True if this target has the MachO
     56     /// .subsections_via_symbols directive.
     57     bool HasSubsectionsViaSymbols;           // Default is false.
     58 
     59     /// HasMachoZeroFillDirective - True if this is a MachO target that supports
     60     /// the macho-specific .zerofill directive for emitting BSS Symbols.
     61     bool HasMachoZeroFillDirective;               // Default is false.
     62 
     63     /// HasMachoTBSSDirective - True if this is a MachO target that supports
     64     /// the macho-specific .tbss directive for emitting thread local BSS Symbols
     65     bool HasMachoTBSSDirective;                 // Default is false.
     66 
     67     /// HasStaticCtorDtorReferenceInStaticMode - True if the compiler should
     68     /// emit a ".reference .constructors_used" or ".reference .destructors_used"
     69     /// directive after the a static ctor/dtor list.  This directive is only
     70     /// emitted in Static relocation model.
     71     bool HasStaticCtorDtorReferenceInStaticMode;  // Default is false.
     72 
     73     /// LinkerRequiresNonEmptyDwarfLines - True if the linker has a bug and
     74     /// requires that the debug_line section be of a minimum size. In practice
     75     /// such a linker requires a non empty line sequence if a file is present.
     76     bool LinkerRequiresNonEmptyDwarfLines; // Default to false.
     77 
     78     /// MaxInstLength - This is the maximum possible length of an instruction,
     79     /// which is needed to compute the size of an inline asm.
     80     unsigned MaxInstLength;                  // Defaults to 4.
     81 
     82     /// PCSymbol - The symbol used to represent the current PC.  Used in PC
     83     /// relative expressions.
     84     const char *PCSymbol;                    // Defaults to "$".
     85 
     86     /// SeparatorString - This string, if specified, is used to separate
     87     /// instructions from each other when on the same line.
     88     const char *SeparatorString;             // Defaults to ';'
     89 
     90     /// CommentColumn - This indicates the comment num (zero-based) at
     91     /// which asm comments should be printed.
     92     unsigned CommentColumn;                  // Defaults to 40
     93 
     94     /// CommentString - This indicates the comment character used by the
     95     /// assembler.
     96     const char *CommentString;               // Defaults to "#"
     97 
     98     /// LabelSuffix - This is appended to emitted labels.
     99     const char *LabelSuffix;                 // Defaults to ":"
    100 
    101     /// GlobalPrefix - If this is set to a non-empty string, it is prepended
    102     /// onto all global symbols.  This is often used for "_" or ".".
    103     const char *GlobalPrefix;                // Defaults to ""
    104 
    105     /// PrivateGlobalPrefix - This prefix is used for globals like constant
    106     /// pool entries that are completely private to the .s file and should not
    107     /// have names in the .o file.  This is often "." or "L".
    108     const char *PrivateGlobalPrefix;         // Defaults to "."
    109 
    110     /// LinkerPrivateGlobalPrefix - This prefix is used for symbols that should
    111     /// be passed through the assembler but be removed by the linker.  This
    112     /// is "l" on Darwin, currently used for some ObjC metadata.
    113     const char *LinkerPrivateGlobalPrefix;   // Defaults to ""
    114 
    115     /// InlineAsmStart/End - If these are nonempty, they contain a directive to
    116     /// emit before and after an inline assembly statement.
    117     const char *InlineAsmStart;              // Defaults to "#APP\n"
    118     const char *InlineAsmEnd;                // Defaults to "#NO_APP\n"
    119 
    120     /// AssemblerDialect - Which dialect of an assembler variant to use.
    121     unsigned AssemblerDialect;               // Defaults to 0
    122 
    123     /// AllowQuotesInName - This is true if the assembler allows for complex
    124     /// symbol names to be surrounded in quotes.  This defaults to false.
    125     bool AllowQuotesInName;
    126 
    127     /// AllowNameToStartWithDigit - This is true if the assembler allows symbol
    128     /// names to start with a digit (e.g., "0x0021").  This defaults to false.
    129     bool AllowNameToStartWithDigit;
    130 
    131     /// AllowPeriodsInName - This is true if the assembler allows periods in
    132     /// symbol names.  This defaults to true.
    133     bool AllowPeriodsInName;
    134 
    135     //===--- Data Emission Directives -------------------------------------===//
    136 
    137     /// ZeroDirective - this should be set to the directive used to get some
    138     /// number of zero bytes emitted to the current section.  Common cases are
    139     /// "\t.zero\t" and "\t.space\t".  If this is set to null, the
    140     /// Data*bitsDirective's will be used to emit zero bytes.
    141     const char *ZeroDirective;               // Defaults to "\t.zero\t"
    142 
    143     /// AsciiDirective - This directive allows emission of an ascii string with
    144     /// the standard C escape characters embedded into it.
    145     const char *AsciiDirective;              // Defaults to "\t.ascii\t"
    146 
    147     /// AscizDirective - If not null, this allows for special handling of
    148     /// zero terminated strings on this target.  This is commonly supported as
    149     /// ".asciz".  If a target doesn't support this, it can be set to null.
    150     const char *AscizDirective;              // Defaults to "\t.asciz\t"
    151 
    152     /// DataDirectives - These directives are used to output some unit of
    153     /// integer data to the current section.  If a data directive is set to
    154     /// null, smaller data directives will be used to emit the large sizes.
    155     const char *Data8bitsDirective;          // Defaults to "\t.byte\t"
    156     const char *Data16bitsDirective;         // Defaults to "\t.short\t"
    157     const char *Data32bitsDirective;         // Defaults to "\t.long\t"
    158     const char *Data64bitsDirective;         // Defaults to "\t.quad\t"
    159 
    160     /// GPRel32Directive - if non-null, a directive that is used to emit a word
    161     /// which should be relocated as a 32-bit GP-relative offset, e.g. .gpword
    162     /// on Mips or .gprel32 on Alpha.
    163     const char *GPRel32Directive;            // Defaults to NULL.
    164 
    165     /// getDataASDirective - Return the directive that should be used to emit
    166     /// data of the specified size to the specified numeric address space.
    167     virtual const char *getDataASDirective(unsigned Size, unsigned AS) const {
    168       assert(AS != 0 && "Don't know the directives for default addr space");
    169       return 0;
    170     }
    171 
    172     /// SunStyleELFSectionSwitchSyntax - This is true if this target uses "Sun
    173     /// Style" syntax for section switching ("#alloc,#write" etc) instead of the
    174     /// normal ELF syntax (,"a,w") in .section directives.
    175     bool SunStyleELFSectionSwitchSyntax;     // Defaults to false.
    176 
    177     /// UsesELFSectionDirectiveForBSS - This is true if this target uses ELF
    178     /// '.section' directive before the '.bss' one. It's used for PPC/Linux
    179     /// which doesn't support the '.bss' directive only.
    180     bool UsesELFSectionDirectiveForBSS;      // Defaults to false.
    181 
    182     /// HasMicrosoftFastStdCallMangling - True if this target uses microsoft
    183     /// style mangling for functions with X86_StdCall/X86_FastCall calling
    184     /// convention.
    185     bool HasMicrosoftFastStdCallMangling;    // Defaults to false.
    186 
    187     //===--- Alignment Information ----------------------------------------===//
    188 
    189     /// AlignDirective - The directive used to emit round up to an alignment
    190     /// boundary.
    191     ///
    192     const char *AlignDirective;              // Defaults to "\t.align\t"
    193 
    194     /// AlignmentIsInBytes - If this is true (the default) then the asmprinter
    195     /// emits ".align N" directives, where N is the number of bytes to align to.
    196     /// Otherwise, it emits ".align log2(N)", e.g. 3 to align to an 8 byte
    197     /// boundary.
    198     bool AlignmentIsInBytes;                 // Defaults to true
    199 
    200     /// TextAlignFillValue - If non-zero, this is used to fill the executable
    201     /// space created as the result of a alignment directive.
    202     unsigned TextAlignFillValue;             // Defaults to 0
    203 
    204     //===--- Global Variable Emission Directives --------------------------===//
    205 
    206     /// GlobalDirective - This is the directive used to declare a global entity.
    207     ///
    208     const char *GlobalDirective;             // Defaults to NULL.
    209 
    210     /// ExternDirective - This is the directive used to declare external
    211     /// globals.
    212     ///
    213     const char *ExternDirective;             // Defaults to NULL.
    214 
    215     /// HasSetDirective - True if the assembler supports the .set directive.
    216     bool HasSetDirective;                    // Defaults to true.
    217 
    218     /// HasAggressiveSymbolFolding - False if the assembler requires that we use
    219     /// Lc = a - b
    220     /// .long Lc
    221     /// instead of
    222     /// .long a - b
    223     bool HasAggressiveSymbolFolding;           // Defaults to true.
    224 
    225     /// HasLCOMMDirective - This is true if the target supports the .lcomm
    226     /// directive.
    227     bool HasLCOMMDirective;                  // Defaults to false.
    228 
    229     /// COMMDirectiveAlignmentIsInBytes - True is COMMDirective's optional
    230     /// alignment is to be specified in bytes instead of log2(n).
    231     bool COMMDirectiveAlignmentIsInBytes;    // Defaults to true;
    232 
    233     /// HasDotTypeDotSizeDirective - True if the target has .type and .size
    234     /// directives, this is true for most ELF targets.
    235     bool HasDotTypeDotSizeDirective;         // Defaults to true.
    236 
    237     /// HasSingleParameterDotFile - True if the target has a single parameter
    238     /// .file directive, this is true for ELF targets.
    239     bool HasSingleParameterDotFile;          // Defaults to true.
    240 
    241     /// HasNoDeadStrip - True if this target supports the MachO .no_dead_strip
    242     /// directive.
    243     bool HasNoDeadStrip;                     // Defaults to false.
    244 
    245     /// HasSymbolResolver - True if this target supports the MachO
    246     /// .symbol_resolver directive.
    247     bool HasSymbolResolver;                     // Defaults to false.
    248 
    249     /// WeakRefDirective - This directive, if non-null, is used to declare a
    250     /// global as being a weak undefined symbol.
    251     const char *WeakRefDirective;            // Defaults to NULL.
    252 
    253     /// WeakDefDirective - This directive, if non-null, is used to declare a
    254     /// global as being a weak defined symbol.
    255     const char *WeakDefDirective;            // Defaults to NULL.
    256 
    257     /// LinkOnceDirective - This directive, if non-null is used to declare a
    258     /// global as being a weak defined symbol.  This is used on cygwin/mingw.
    259     const char *LinkOnceDirective;           // Defaults to NULL.
    260 
    261     /// HiddenVisibilityAttr - This attribute, if not MCSA_Invalid, is used to
    262     /// declare a symbol as having hidden visibility.
    263     MCSymbolAttr HiddenVisibilityAttr;       // Defaults to MCSA_Hidden.
    264 
    265     /// HiddenDeclarationVisibilityAttr - This attribute, if not MCSA_Invalid,
    266     /// is used to declare an undefined symbol as having hidden visibility.
    267     MCSymbolAttr HiddenDeclarationVisibilityAttr;   // Defaults to MCSA_Hidden.
    268 
    269 
    270     /// ProtectedVisibilityAttr - This attribute, if not MCSA_Invalid, is used
    271     /// to declare a symbol as having protected visibility.
    272     MCSymbolAttr ProtectedVisibilityAttr;    // Defaults to MCSA_Protected
    273 
    274     //===--- Dwarf Emission Directives -----------------------------------===//
    275 
    276     /// HasLEB128 - True if target asm supports leb128 directives.
    277     bool HasLEB128;                          // Defaults to false.
    278 
    279     /// SupportsDebugInformation - True if target supports emission of debugging
    280     /// information.
    281     bool SupportsDebugInformation;           // Defaults to false.
    282 
    283     /// SupportsExceptionHandling - True if target supports exception handling.
    284     ExceptionHandling::ExceptionsType ExceptionsType; // Defaults to None
    285 
    286     /// DwarfUsesInlineInfoSection - True if DwarfDebugInlineSection is used to
    287     /// encode inline subroutine information.
    288     bool DwarfUsesInlineInfoSection;         // Defaults to false.
    289 
    290     /// DwarfSectionOffsetDirective - Special section offset directive.
    291     const char* DwarfSectionOffsetDirective; // Defaults to NULL
    292 
    293     /// DwarfRequiresRelocationForSectionOffset - True if we need to produce a
    294     // relocation when we want a section offset in dwarf.
    295     bool DwarfRequiresRelocationForSectionOffset;  // Defaults to true;
    296 
    297     // DwarfUsesLabelOffsetDifference - True if Dwarf2 output can
    298     // use EmitLabelOffsetDifference.
    299     bool DwarfUsesLabelOffsetForRanges;
    300 
    301     /// DwarfRegNumForCFI - True if dwarf register numbers are printed
    302     /// instead of symbolic register names in .cfi_* directives.
    303     bool DwarfRegNumForCFI;  // Defaults to false;
    304 
    305     //===--- CBE Asm Translation Table -----------------------------------===//
    306 
    307     const char *const *AsmTransCBE;          // Defaults to empty
    308 
    309     //===--- Prologue State ----------------------------------------------===//
    310 
    311     std::vector<MachineMove> InitialFrameState;
    312 
    313   public:
    314     explicit MCAsmInfo();
    315     virtual ~MCAsmInfo();
    316 
    317     // FIXME: move these methods to DwarfPrinter when the JIT stops using them.
    318     static unsigned getSLEB128Size(int Value);
    319     static unsigned getULEB128Size(unsigned Value);
    320 
    321     /// getPointerSize - Get the pointer size in bytes.
    322     unsigned getPointerSize() const {
    323       return PointerSize;
    324     }
    325 
    326     /// islittleendian - True if the target is little endian.
    327     bool isLittleEndian() const {
    328       return IsLittleEndian;
    329     }
    330 
    331     /// isStackGrowthDirectionUp - True if target stack grow up.
    332     bool isStackGrowthDirectionUp() const {
    333       return StackGrowsUp;
    334     }
    335 
    336     bool hasSubsectionsViaSymbols() const { return HasSubsectionsViaSymbols; }
    337 
    338     // Data directive accessors.
    339     //
    340     const char *getData8bitsDirective(unsigned AS = 0) const {
    341       return AS == 0 ? Data8bitsDirective : getDataASDirective(8, AS);
    342     }
    343     const char *getData16bitsDirective(unsigned AS = 0) const {
    344       return AS == 0 ? Data16bitsDirective : getDataASDirective(16, AS);
    345     }
    346     const char *getData32bitsDirective(unsigned AS = 0) const {
    347       return AS == 0 ? Data32bitsDirective : getDataASDirective(32, AS);
    348     }
    349     const char *getData64bitsDirective(unsigned AS = 0) const {
    350       return AS == 0 ? Data64bitsDirective : getDataASDirective(64, AS);
    351     }
    352     const char *getGPRel32Directive() const { return GPRel32Directive; }
    353 
    354     /// getNonexecutableStackSection - Targets can implement this method to
    355     /// specify a section to switch to if the translation unit doesn't have any
    356     /// trampolines that require an executable stack.
    357     virtual const MCSection *getNonexecutableStackSection(MCContext &Ctx) const{
    358       return 0;
    359     }
    360 
    361     virtual const MCExpr *
    362     getExprForPersonalitySymbol(const MCSymbol *Sym,
    363                                 unsigned Encoding,
    364                                 MCStreamer &Streamer) const;
    365 
    366     const MCExpr *
    367     getExprForFDESymbol(const MCSymbol *Sym,
    368                         unsigned Encoding,
    369                         MCStreamer &Streamer) const;
    370 
    371     bool usesSunStyleELFSectionSwitchSyntax() const {
    372       return SunStyleELFSectionSwitchSyntax;
    373     }
    374 
    375     bool usesELFSectionDirectiveForBSS() const {
    376       return UsesELFSectionDirectiveForBSS;
    377     }
    378 
    379     bool hasMicrosoftFastStdCallMangling() const {
    380       return HasMicrosoftFastStdCallMangling;
    381     }
    382 
    383     // Accessors.
    384     //
    385     bool hasMachoZeroFillDirective() const { return HasMachoZeroFillDirective; }
    386     bool hasMachoTBSSDirective() const { return HasMachoTBSSDirective; }
    387     bool hasStaticCtorDtorReferenceInStaticMode() const {
    388       return HasStaticCtorDtorReferenceInStaticMode;
    389     }
    390     bool getLinkerRequiresNonEmptyDwarfLines() const {
    391       return LinkerRequiresNonEmptyDwarfLines;
    392     }
    393     unsigned getMaxInstLength() const {
    394       return MaxInstLength;
    395     }
    396     const char *getPCSymbol() const {
    397       return PCSymbol;
    398     }
    399     const char *getSeparatorString() const {
    400       return SeparatorString;
    401     }
    402     unsigned getCommentColumn() const {
    403       return CommentColumn;
    404     }
    405     const char *getCommentString() const {
    406       return CommentString;
    407     }
    408     const char *getLabelSuffix() const {
    409       return LabelSuffix;
    410     }
    411     const char *getGlobalPrefix() const {
    412       return GlobalPrefix;
    413     }
    414     const char *getPrivateGlobalPrefix() const {
    415       return PrivateGlobalPrefix;
    416     }
    417     const char *getLinkerPrivateGlobalPrefix() const {
    418       return LinkerPrivateGlobalPrefix;
    419     }
    420     const char *getInlineAsmStart() const {
    421       return InlineAsmStart;
    422     }
    423     const char *getInlineAsmEnd() const {
    424       return InlineAsmEnd;
    425     }
    426     unsigned getAssemblerDialect() const {
    427       return AssemblerDialect;
    428     }
    429     bool doesAllowQuotesInName() const {
    430       return AllowQuotesInName;
    431     }
    432     bool doesAllowNameToStartWithDigit() const {
    433       return AllowNameToStartWithDigit;
    434     }
    435     bool doesAllowPeriodsInName() const {
    436       return AllowPeriodsInName;
    437     }
    438     const char *getZeroDirective() const {
    439       return ZeroDirective;
    440     }
    441     const char *getAsciiDirective() const {
    442       return AsciiDirective;
    443     }
    444     const char *getAscizDirective() const {
    445       return AscizDirective;
    446     }
    447     const char *getAlignDirective() const {
    448       return AlignDirective;
    449     }
    450     bool getAlignmentIsInBytes() const {
    451       return AlignmentIsInBytes;
    452     }
    453     unsigned getTextAlignFillValue() const {
    454       return TextAlignFillValue;
    455     }
    456     const char *getGlobalDirective() const {
    457       return GlobalDirective;
    458     }
    459     const char *getExternDirective() const {
    460       return ExternDirective;
    461     }
    462     bool hasSetDirective() const { return HasSetDirective; }
    463     bool hasAggressiveSymbolFolding() const {
    464       return HasAggressiveSymbolFolding;
    465     }
    466     bool hasLCOMMDirective() const { return HasLCOMMDirective; }
    467     bool hasDotTypeDotSizeDirective() const {return HasDotTypeDotSizeDirective;}
    468     bool getCOMMDirectiveAlignmentIsInBytes() const {
    469       return COMMDirectiveAlignmentIsInBytes;
    470     }
    471     bool hasSingleParameterDotFile() const { return HasSingleParameterDotFile; }
    472     bool hasNoDeadStrip() const { return HasNoDeadStrip; }
    473     bool hasSymbolResolver() const { return HasSymbolResolver; }
    474     const char *getWeakRefDirective() const { return WeakRefDirective; }
    475     const char *getWeakDefDirective() const { return WeakDefDirective; }
    476     const char *getLinkOnceDirective() const { return LinkOnceDirective; }
    477 
    478     MCSymbolAttr getHiddenVisibilityAttr() const { return HiddenVisibilityAttr;}
    479     MCSymbolAttr getHiddenDeclarationVisibilityAttr() const {
    480       return HiddenDeclarationVisibilityAttr;
    481     }
    482     MCSymbolAttr getProtectedVisibilityAttr() const {
    483       return ProtectedVisibilityAttr;
    484     }
    485     bool hasLEB128() const {
    486       return HasLEB128;
    487     }
    488     bool doesSupportDebugInformation() const {
    489       return SupportsDebugInformation;
    490     }
    491     bool doesSupportExceptionHandling() const {
    492       return ExceptionsType != ExceptionHandling::None;
    493     }
    494     ExceptionHandling::ExceptionsType getExceptionHandlingType() const {
    495       return ExceptionsType;
    496     }
    497     bool isExceptionHandlingDwarf() const {
    498       return
    499         (ExceptionsType == ExceptionHandling::DwarfCFI ||
    500          ExceptionsType == ExceptionHandling::ARM ||
    501          ExceptionsType == ExceptionHandling::Win64);
    502     }
    503     bool doesDwarfUsesInlineInfoSection() const {
    504       return DwarfUsesInlineInfoSection;
    505     }
    506     const char *getDwarfSectionOffsetDirective() const {
    507       return DwarfSectionOffsetDirective;
    508     }
    509     bool doesDwarfRequireRelocationForSectionOffset() const {
    510       return DwarfRequiresRelocationForSectionOffset;
    511     }
    512     bool doesDwarfUsesLabelOffsetForRanges() const {
    513       return DwarfUsesLabelOffsetForRanges;
    514     }
    515     bool useDwarfRegNumForCFI() const {
    516       return DwarfRegNumForCFI;
    517     }
    518     const char *const *getAsmCBE() const {
    519       return AsmTransCBE;
    520     }
    521 
    522     void addInitialFrameState(MCSymbol *label, const MachineLocation &D,
    523                               const MachineLocation &S) {
    524       InitialFrameState.push_back(MachineMove(label, D, S));
    525     }
    526     const std::vector<MachineMove> &getInitialFrameState() const {
    527       return InitialFrameState;
    528     }
    529   };
    530 }
    531 
    532 #endif
    533