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      1 //===--- TargetInfo.h - Expose information about the target -----*- 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 /// \file
     11 /// \brief Defines the clang::TargetInfo interface.
     12 ///
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_CLANG_BASIC_TARGETINFO_H
     16 #define LLVM_CLANG_BASIC_TARGETINFO_H
     17 
     18 #include "clang/Basic/AddressSpaces.h"
     19 #include "clang/Basic/LLVM.h"
     20 #include "clang/Basic/Specifiers.h"
     21 #include "clang/Basic/TargetCXXABI.h"
     22 #include "clang/Basic/TargetOptions.h"
     23 #include "clang/Basic/VersionTuple.h"
     24 #include "llvm/ADT/IntrusiveRefCntPtr.h"
     25 #include "llvm/ADT/StringMap.h"
     26 #include "llvm/ADT/StringRef.h"
     27 #include "llvm/ADT/StringSwitch.h"
     28 #include "llvm/ADT/Triple.h"
     29 #include "llvm/Support/DataTypes.h"
     30 #include <cassert>
     31 #include <string>
     32 #include <vector>
     33 
     34 namespace llvm {
     35 struct fltSemantics;
     36 }
     37 
     38 namespace clang {
     39 class DiagnosticsEngine;
     40 class LangOptions;
     41 class MacroBuilder;
     42 class SourceLocation;
     43 class SourceManager;
     44 
     45 namespace Builtin { struct Info; }
     46 
     47 /// \brief Exposes information about the current target.
     48 ///
     49 class TargetInfo : public RefCountedBase<TargetInfo> {
     50   std::shared_ptr<TargetOptions> TargetOpts;
     51   llvm::Triple Triple;
     52 protected:
     53   // Target values set by the ctor of the actual target implementation.  Default
     54   // values are specified by the TargetInfo constructor.
     55   bool BigEndian;
     56   bool TLSSupported;
     57   bool NoAsmVariants;  // True if {|} are normal characters.
     58   unsigned char PointerWidth, PointerAlign;
     59   unsigned char BoolWidth, BoolAlign;
     60   unsigned char IntWidth, IntAlign;
     61   unsigned char HalfWidth, HalfAlign;
     62   unsigned char FloatWidth, FloatAlign;
     63   unsigned char DoubleWidth, DoubleAlign;
     64   unsigned char LongDoubleWidth, LongDoubleAlign;
     65   unsigned char LargeArrayMinWidth, LargeArrayAlign;
     66   unsigned char LongWidth, LongAlign;
     67   unsigned char LongLongWidth, LongLongAlign;
     68   unsigned char SuitableAlign;
     69   unsigned char MinGlobalAlign;
     70   unsigned char MaxAtomicPromoteWidth, MaxAtomicInlineWidth;
     71   unsigned short MaxVectorAlign;
     72   const char *DescriptionString;
     73   const char *UserLabelPrefix;
     74   const char *MCountName;
     75   const llvm::fltSemantics *HalfFormat, *FloatFormat, *DoubleFormat,
     76     *LongDoubleFormat;
     77   unsigned char RegParmMax, SSERegParmMax;
     78   TargetCXXABI TheCXXABI;
     79   const LangAS::Map *AddrSpaceMap;
     80 
     81   mutable StringRef PlatformName;
     82   mutable VersionTuple PlatformMinVersion;
     83 
     84   unsigned HasAlignMac68kSupport : 1;
     85   unsigned RealTypeUsesObjCFPRet : 3;
     86   unsigned ComplexLongDoubleUsesFP2Ret : 1;
     87 
     88   // TargetInfo Constructor.  Default initializes all fields.
     89   TargetInfo(const llvm::Triple &T);
     90 
     91 public:
     92   /// \brief Construct a target for the given options.
     93   ///
     94   /// \param Opts - The options to use to initialize the target. The target may
     95   /// modify the options to canonicalize the target feature information to match
     96   /// what the backend expects.
     97   static TargetInfo *
     98   CreateTargetInfo(DiagnosticsEngine &Diags,
     99                    const std::shared_ptr<TargetOptions> &Opts);
    100 
    101   virtual ~TargetInfo();
    102 
    103   /// \brief Retrieve the target options.
    104   TargetOptions &getTargetOpts() const {
    105     assert(TargetOpts && "Missing target options");
    106     return *TargetOpts;
    107   }
    108 
    109   ///===---- Target Data Type Query Methods -------------------------------===//
    110   enum IntType {
    111     NoInt = 0,
    112     SignedChar,
    113     UnsignedChar,
    114     SignedShort,
    115     UnsignedShort,
    116     SignedInt,
    117     UnsignedInt,
    118     SignedLong,
    119     UnsignedLong,
    120     SignedLongLong,
    121     UnsignedLongLong
    122   };
    123 
    124   enum RealType {
    125     NoFloat = 255,
    126     Float = 0,
    127     Double,
    128     LongDouble
    129   };
    130 
    131   /// \brief The different kinds of __builtin_va_list types defined by
    132   /// the target implementation.
    133   enum BuiltinVaListKind {
    134     /// typedef char* __builtin_va_list;
    135     CharPtrBuiltinVaList = 0,
    136 
    137     /// typedef void* __builtin_va_list;
    138     VoidPtrBuiltinVaList,
    139 
    140     /// __builtin_va_list as defind by the AArch64 ABI
    141     /// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0055a/IHI0055A_aapcs64.pdf
    142     AArch64ABIBuiltinVaList,
    143 
    144     /// __builtin_va_list as defined by the PNaCl ABI:
    145     /// http://www.chromium.org/nativeclient/pnacl/bitcode-abi#TOC-Machine-Types
    146     PNaClABIBuiltinVaList,
    147 
    148     /// __builtin_va_list as defined by the Power ABI:
    149     /// https://www.power.org
    150     ///        /resources/downloads/Power-Arch-32-bit-ABI-supp-1.0-Embedded.pdf
    151     PowerABIBuiltinVaList,
    152 
    153     /// __builtin_va_list as defined by the x86-64 ABI:
    154     /// http://www.x86-64.org/documentation/abi.pdf
    155     X86_64ABIBuiltinVaList,
    156 
    157     /// __builtin_va_list as defined by ARM AAPCS ABI
    158     /// http://infocenter.arm.com
    159     //        /help/topic/com.arm.doc.ihi0042d/IHI0042D_aapcs.pdf
    160     AAPCSABIBuiltinVaList,
    161 
    162     // typedef struct __va_list_tag
    163     //   {
    164     //     long __gpr;
    165     //     long __fpr;
    166     //     void *__overflow_arg_area;
    167     //     void *__reg_save_area;
    168     //   } va_list[1];
    169     SystemZBuiltinVaList
    170   };
    171 
    172 protected:
    173   IntType SizeType, IntMaxType, UIntMaxType, PtrDiffType, IntPtrType, WCharType,
    174           WIntType, Char16Type, Char32Type, Int64Type, SigAtomicType,
    175           ProcessIDType;
    176 
    177   /// \brief Whether Objective-C's built-in boolean type should be signed char.
    178   ///
    179   /// Otherwise, when this flag is not set, the normal built-in boolean type is
    180   /// used.
    181   unsigned UseSignedCharForObjCBool : 1;
    182 
    183   /// Control whether the alignment of bit-field types is respected when laying
    184   /// out structures. If true, then the alignment of the bit-field type will be
    185   /// used to (a) impact the alignment of the containing structure, and (b)
    186   /// ensure that the individual bit-field will not straddle an alignment
    187   /// boundary.
    188   unsigned UseBitFieldTypeAlignment : 1;
    189 
    190   /// \brief Whether zero length bitfields (e.g., int : 0;) force alignment of
    191   /// the next bitfield.
    192   ///
    193   /// If the alignment of the zero length bitfield is greater than the member
    194   /// that follows it, `bar', `bar' will be aligned as the type of the
    195   /// zero-length bitfield.
    196   unsigned UseZeroLengthBitfieldAlignment : 1;
    197 
    198   /// If non-zero, specifies a fixed alignment value for bitfields that follow
    199   /// zero length bitfield, regardless of the zero length bitfield type.
    200   unsigned ZeroLengthBitfieldBoundary;
    201 
    202   /// \brief Specify if mangling based on address space map should be used or
    203   /// not for language specific address spaces
    204   bool UseAddrSpaceMapMangling;
    205 
    206 public:
    207   IntType getSizeType() const { return SizeType; }
    208   IntType getIntMaxType() const { return IntMaxType; }
    209   IntType getUIntMaxType() const { return UIntMaxType; }
    210   IntType getPtrDiffType(unsigned AddrSpace) const {
    211     return AddrSpace == 0 ? PtrDiffType : getPtrDiffTypeV(AddrSpace);
    212   }
    213   IntType getIntPtrType() const { return IntPtrType; }
    214   IntType getUIntPtrType() const {
    215     return getIntTypeByWidth(getTypeWidth(IntPtrType), false);
    216   }
    217   IntType getWCharType() const { return WCharType; }
    218   IntType getWIntType() const { return WIntType; }
    219   IntType getChar16Type() const { return Char16Type; }
    220   IntType getChar32Type() const { return Char32Type; }
    221   IntType getInt64Type() const { return Int64Type; }
    222   IntType getSigAtomicType() const { return SigAtomicType; }
    223   IntType getProcessIDType() const { return ProcessIDType; }
    224 
    225   /// \brief Return the width (in bits) of the specified integer type enum.
    226   ///
    227   /// For example, SignedInt -> getIntWidth().
    228   unsigned getTypeWidth(IntType T) const;
    229 
    230   /// \brief Return integer type with specified width.
    231   IntType getIntTypeByWidth(unsigned BitWidth, bool IsSigned) const;
    232 
    233   /// \brief Return the smallest integer type with at least the specified width.
    234   IntType getLeastIntTypeByWidth(unsigned BitWidth, bool IsSigned) const;
    235 
    236   /// \brief Return floating point type with specified width.
    237   RealType getRealTypeByWidth(unsigned BitWidth) const;
    238 
    239   /// \brief Return the alignment (in bits) of the specified integer type enum.
    240   ///
    241   /// For example, SignedInt -> getIntAlign().
    242   unsigned getTypeAlign(IntType T) const;
    243 
    244   /// \brief Returns true if the type is signed; false otherwise.
    245   static bool isTypeSigned(IntType T);
    246 
    247   /// \brief Return the width of pointers on this target, for the
    248   /// specified address space.
    249   uint64_t getPointerWidth(unsigned AddrSpace) const {
    250     return AddrSpace == 0 ? PointerWidth : getPointerWidthV(AddrSpace);
    251   }
    252   uint64_t getPointerAlign(unsigned AddrSpace) const {
    253     return AddrSpace == 0 ? PointerAlign : getPointerAlignV(AddrSpace);
    254   }
    255 
    256   /// \brief Return the size of '_Bool' and C++ 'bool' for this target, in bits.
    257   unsigned getBoolWidth() const { return BoolWidth; }
    258 
    259   /// \brief Return the alignment of '_Bool' and C++ 'bool' for this target.
    260   unsigned getBoolAlign() const { return BoolAlign; }
    261 
    262   unsigned getCharWidth() const { return 8; } // FIXME
    263   unsigned getCharAlign() const { return 8; } // FIXME
    264 
    265   /// \brief Return the size of 'signed short' and 'unsigned short' for this
    266   /// target, in bits.
    267   unsigned getShortWidth() const { return 16; } // FIXME
    268 
    269   /// \brief Return the alignment of 'signed short' and 'unsigned short' for
    270   /// this target.
    271   unsigned getShortAlign() const { return 16; } // FIXME
    272 
    273   /// getIntWidth/Align - Return the size of 'signed int' and 'unsigned int' for
    274   /// this target, in bits.
    275   unsigned getIntWidth() const { return IntWidth; }
    276   unsigned getIntAlign() const { return IntAlign; }
    277 
    278   /// getLongWidth/Align - Return the size of 'signed long' and 'unsigned long'
    279   /// for this target, in bits.
    280   unsigned getLongWidth() const { return LongWidth; }
    281   unsigned getLongAlign() const { return LongAlign; }
    282 
    283   /// getLongLongWidth/Align - Return the size of 'signed long long' and
    284   /// 'unsigned long long' for this target, in bits.
    285   unsigned getLongLongWidth() const { return LongLongWidth; }
    286   unsigned getLongLongAlign() const { return LongLongAlign; }
    287 
    288   /// \brief Determine whether the __int128 type is supported on this target.
    289   virtual bool hasInt128Type() const { return getPointerWidth(0) >= 64; } // FIXME
    290 
    291   /// \brief Return the alignment that is suitable for storing any
    292   /// object with a fundamental alignment requirement.
    293   unsigned getSuitableAlign() const { return SuitableAlign; }
    294 
    295   /// getMinGlobalAlign - Return the minimum alignment of a global variable,
    296   /// unless its alignment is explicitly reduced via attributes.
    297   unsigned getMinGlobalAlign() const { return MinGlobalAlign; }
    298 
    299   /// getWCharWidth/Align - Return the size of 'wchar_t' for this target, in
    300   /// bits.
    301   unsigned getWCharWidth() const { return getTypeWidth(WCharType); }
    302   unsigned getWCharAlign() const { return getTypeAlign(WCharType); }
    303 
    304   /// getChar16Width/Align - Return the size of 'char16_t' for this target, in
    305   /// bits.
    306   unsigned getChar16Width() const { return getTypeWidth(Char16Type); }
    307   unsigned getChar16Align() const { return getTypeAlign(Char16Type); }
    308 
    309   /// getChar32Width/Align - Return the size of 'char32_t' for this target, in
    310   /// bits.
    311   unsigned getChar32Width() const { return getTypeWidth(Char32Type); }
    312   unsigned getChar32Align() const { return getTypeAlign(Char32Type); }
    313 
    314   /// getHalfWidth/Align/Format - Return the size/align/format of 'half'.
    315   unsigned getHalfWidth() const { return HalfWidth; }
    316   unsigned getHalfAlign() const { return HalfAlign; }
    317   const llvm::fltSemantics &getHalfFormat() const { return *HalfFormat; }
    318 
    319   /// getFloatWidth/Align/Format - Return the size/align/format of 'float'.
    320   unsigned getFloatWidth() const { return FloatWidth; }
    321   unsigned getFloatAlign() const { return FloatAlign; }
    322   const llvm::fltSemantics &getFloatFormat() const { return *FloatFormat; }
    323 
    324   /// getDoubleWidth/Align/Format - Return the size/align/format of 'double'.
    325   unsigned getDoubleWidth() const { return DoubleWidth; }
    326   unsigned getDoubleAlign() const { return DoubleAlign; }
    327   const llvm::fltSemantics &getDoubleFormat() const { return *DoubleFormat; }
    328 
    329   /// getLongDoubleWidth/Align/Format - Return the size/align/format of 'long
    330   /// double'.
    331   unsigned getLongDoubleWidth() const { return LongDoubleWidth; }
    332   unsigned getLongDoubleAlign() const { return LongDoubleAlign; }
    333   const llvm::fltSemantics &getLongDoubleFormat() const {
    334     return *LongDoubleFormat;
    335   }
    336 
    337   /// \brief Return the value for the C99 FLT_EVAL_METHOD macro.
    338   virtual unsigned getFloatEvalMethod() const { return 0; }
    339 
    340   // getLargeArrayMinWidth/Align - Return the minimum array size that is
    341   // 'large' and its alignment.
    342   unsigned getLargeArrayMinWidth() const { return LargeArrayMinWidth; }
    343   unsigned getLargeArrayAlign() const { return LargeArrayAlign; }
    344 
    345   /// \brief Return the maximum width lock-free atomic operation which will
    346   /// ever be supported for the given target
    347   unsigned getMaxAtomicPromoteWidth() const { return MaxAtomicPromoteWidth; }
    348   /// \brief Return the maximum width lock-free atomic operation which can be
    349   /// inlined given the supported features of the given target.
    350   unsigned getMaxAtomicInlineWidth() const { return MaxAtomicInlineWidth; }
    351 
    352   /// \brief Return the maximum vector alignment supported for the given target.
    353   unsigned getMaxVectorAlign() const { return MaxVectorAlign; }
    354 
    355   /// \brief Return the size of intmax_t and uintmax_t for this target, in bits.
    356   unsigned getIntMaxTWidth() const {
    357     return getTypeWidth(IntMaxType);
    358   }
    359 
    360   // Return the size of unwind_word for this target.
    361   unsigned getUnwindWordWidth() const { return getPointerWidth(0); }
    362 
    363   /// \brief Return the "preferred" register width on this target.
    364   unsigned getRegisterWidth() const {
    365     // Currently we assume the register width on the target matches the pointer
    366     // width, we can introduce a new variable for this if/when some target wants
    367     // it.
    368     return PointerWidth;
    369   }
    370 
    371   /// \brief Returns the default value of the __USER_LABEL_PREFIX__ macro,
    372   /// which is the prefix given to user symbols by default.
    373   ///
    374   /// On most platforms this is "_", but it is "" on some, and "." on others.
    375   const char *getUserLabelPrefix() const {
    376     return UserLabelPrefix;
    377   }
    378 
    379   /// \brief Returns the name of the mcount instrumentation function.
    380   const char *getMCountName() const {
    381     return MCountName;
    382   }
    383 
    384   /// \brief Check if the Objective-C built-in boolean type should be signed
    385   /// char.
    386   ///
    387   /// Otherwise, if this returns false, the normal built-in boolean type
    388   /// should also be used for Objective-C.
    389   bool useSignedCharForObjCBool() const {
    390     return UseSignedCharForObjCBool;
    391   }
    392   void noSignedCharForObjCBool() {
    393     UseSignedCharForObjCBool = false;
    394   }
    395 
    396   /// \brief Check whether the alignment of bit-field types is respected
    397   /// when laying out structures.
    398   bool useBitFieldTypeAlignment() const {
    399     return UseBitFieldTypeAlignment;
    400   }
    401 
    402   /// \brief Check whether zero length bitfields should force alignment of
    403   /// the next member.
    404   bool useZeroLengthBitfieldAlignment() const {
    405     return UseZeroLengthBitfieldAlignment;
    406   }
    407 
    408   /// \brief Get the fixed alignment value in bits for a member that follows
    409   /// a zero length bitfield.
    410   unsigned getZeroLengthBitfieldBoundary() const {
    411     return ZeroLengthBitfieldBoundary;
    412   }
    413 
    414   /// \brief Check whether this target support '\#pragma options align=mac68k'.
    415   bool hasAlignMac68kSupport() const {
    416     return HasAlignMac68kSupport;
    417   }
    418 
    419   /// \brief Return the user string for the specified integer type enum.
    420   ///
    421   /// For example, SignedShort -> "short".
    422   static const char *getTypeName(IntType T);
    423 
    424   /// \brief Return the constant suffix for the specified integer type enum.
    425   ///
    426   /// For example, SignedLong -> "L".
    427   static const char *getTypeConstantSuffix(IntType T);
    428 
    429   /// \brief Check whether the given real type should use the "fpret" flavor of
    430   /// Objective-C message passing on this target.
    431   bool useObjCFPRetForRealType(RealType T) const {
    432     return RealTypeUsesObjCFPRet & (1 << T);
    433   }
    434 
    435   /// \brief Check whether _Complex long double should use the "fp2ret" flavor
    436   /// of Objective-C message passing on this target.
    437   bool useObjCFP2RetForComplexLongDouble() const {
    438     return ComplexLongDoubleUsesFP2Ret;
    439   }
    440 
    441   /// \brief Specify if mangling based on address space map should be used or
    442   /// not for language specific address spaces
    443   bool useAddressSpaceMapMangling() const {
    444     return UseAddrSpaceMapMangling;
    445   }
    446 
    447   ///===---- Other target property query methods --------------------------===//
    448 
    449   /// \brief Appends the target-specific \#define values for this
    450   /// target set to the specified buffer.
    451   virtual void getTargetDefines(const LangOptions &Opts,
    452                                 MacroBuilder &Builder) const = 0;
    453 
    454 
    455   /// Return information about target-specific builtins for
    456   /// the current primary target, and info about which builtins are non-portable
    457   /// across the current set of primary and secondary targets.
    458   virtual void getTargetBuiltins(const Builtin::Info *&Records,
    459                                  unsigned &NumRecords) const = 0;
    460 
    461   /// The __builtin_clz* and __builtin_ctz* built-in
    462   /// functions are specified to have undefined results for zero inputs, but
    463   /// on targets that support these operations in a way that provides
    464   /// well-defined results for zero without loss of performance, it is a good
    465   /// idea to avoid optimizing based on that undef behavior.
    466   virtual bool isCLZForZeroUndef() const { return true; }
    467 
    468   /// \brief Returns the kind of __builtin_va_list type that should be used
    469   /// with this target.
    470   virtual BuiltinVaListKind getBuiltinVaListKind() const = 0;
    471 
    472   /// \brief Returns whether the passed in string is a valid clobber in an
    473   /// inline asm statement.
    474   ///
    475   /// This is used by Sema.
    476   bool isValidClobber(StringRef Name) const;
    477 
    478   /// \brief Returns whether the passed in string is a valid register name
    479   /// according to GCC.
    480   ///
    481   /// This is used by Sema for inline asm statements.
    482   bool isValidGCCRegisterName(StringRef Name) const;
    483 
    484   /// \brief Returns the "normalized" GCC register name.
    485   ///
    486   /// For example, on x86 it will return "ax" when "eax" is passed in.
    487   StringRef getNormalizedGCCRegisterName(StringRef Name) const;
    488 
    489   struct ConstraintInfo {
    490     enum {
    491       CI_None = 0x00,
    492       CI_AllowsMemory = 0x01,
    493       CI_AllowsRegister = 0x02,
    494       CI_ReadWrite = 0x04,       // "+r" output constraint (read and write).
    495       CI_HasMatchingInput = 0x08 // This output operand has a matching input.
    496     };
    497     unsigned Flags;
    498     int TiedOperand;
    499 
    500     std::string ConstraintStr;  // constraint: "=rm"
    501     std::string Name;           // Operand name: [foo] with no []'s.
    502   public:
    503     ConstraintInfo(StringRef ConstraintStr, StringRef Name)
    504       : Flags(0), TiedOperand(-1), ConstraintStr(ConstraintStr.str()),
    505       Name(Name.str()) {}
    506 
    507     const std::string &getConstraintStr() const { return ConstraintStr; }
    508     const std::string &getName() const { return Name; }
    509     bool isReadWrite() const { return (Flags & CI_ReadWrite) != 0; }
    510     bool allowsRegister() const { return (Flags & CI_AllowsRegister) != 0; }
    511     bool allowsMemory() const { return (Flags & CI_AllowsMemory) != 0; }
    512 
    513     /// \brief Return true if this output operand has a matching
    514     /// (tied) input operand.
    515     bool hasMatchingInput() const { return (Flags & CI_HasMatchingInput) != 0; }
    516 
    517     /// \brief Return true if this input operand is a matching
    518     /// constraint that ties it to an output operand.
    519     ///
    520     /// If this returns true then getTiedOperand will indicate which output
    521     /// operand this is tied to.
    522     bool hasTiedOperand() const { return TiedOperand != -1; }
    523     unsigned getTiedOperand() const {
    524       assert(hasTiedOperand() && "Has no tied operand!");
    525       return (unsigned)TiedOperand;
    526     }
    527 
    528     void setIsReadWrite() { Flags |= CI_ReadWrite; }
    529     void setAllowsMemory() { Flags |= CI_AllowsMemory; }
    530     void setAllowsRegister() { Flags |= CI_AllowsRegister; }
    531     void setHasMatchingInput() { Flags |= CI_HasMatchingInput; }
    532 
    533     /// \brief Indicate that this is an input operand that is tied to
    534     /// the specified output operand.
    535     ///
    536     /// Copy over the various constraint information from the output.
    537     void setTiedOperand(unsigned N, ConstraintInfo &Output) {
    538       Output.setHasMatchingInput();
    539       Flags = Output.Flags;
    540       TiedOperand = N;
    541       // Don't copy Name or constraint string.
    542     }
    543   };
    544 
    545   // validateOutputConstraint, validateInputConstraint - Checks that
    546   // a constraint is valid and provides information about it.
    547   // FIXME: These should return a real error instead of just true/false.
    548   bool validateOutputConstraint(ConstraintInfo &Info) const;
    549   bool validateInputConstraint(ConstraintInfo *OutputConstraints,
    550                                unsigned NumOutputs,
    551                                ConstraintInfo &info) const;
    552   virtual bool validateInputSize(StringRef /*Constraint*/,
    553                                  unsigned /*Size*/) const {
    554     return true;
    555   }
    556   virtual bool validateConstraintModifier(StringRef /*Constraint*/,
    557                                           const char /*Modifier*/,
    558                                           unsigned /*Size*/) const {
    559     return true;
    560   }
    561   bool resolveSymbolicName(const char *&Name,
    562                            ConstraintInfo *OutputConstraints,
    563                            unsigned NumOutputs, unsigned &Index) const;
    564 
    565   // Constraint parm will be left pointing at the last character of
    566   // the constraint.  In practice, it won't be changed unless the
    567   // constraint is longer than one character.
    568   virtual std::string convertConstraint(const char *&Constraint) const {
    569     // 'p' defaults to 'r', but can be overridden by targets.
    570     if (*Constraint == 'p')
    571       return std::string("r");
    572     return std::string(1, *Constraint);
    573   }
    574 
    575   /// \brief Returns a string of target-specific clobbers, in LLVM format.
    576   virtual const char *getClobbers() const = 0;
    577 
    578 
    579   /// \brief Returns the target triple of the primary target.
    580   const llvm::Triple &getTriple() const {
    581     return Triple;
    582   }
    583 
    584   const char *getTargetDescription() const {
    585     assert(DescriptionString);
    586     return DescriptionString;
    587   }
    588 
    589   struct GCCRegAlias {
    590     const char * const Aliases[5];
    591     const char * const Register;
    592   };
    593 
    594   struct AddlRegName {
    595     const char * const Names[5];
    596     const unsigned RegNum;
    597   };
    598 
    599   /// \brief Does this target support "protected" visibility?
    600   ///
    601   /// Any target which dynamic libraries will naturally support
    602   /// something like "default" (meaning that the symbol is visible
    603   /// outside this shared object) and "hidden" (meaning that it isn't)
    604   /// visibilities, but "protected" is really an ELF-specific concept
    605   /// with weird semantics designed around the convenience of dynamic
    606   /// linker implementations.  Which is not to suggest that there's
    607   /// consistent target-independent semantics for "default" visibility
    608   /// either; the entire thing is pretty badly mangled.
    609   virtual bool hasProtectedVisibility() const { return true; }
    610 
    611   /// \brief An optional hook that targets can implement to perform semantic
    612   /// checking on attribute((section("foo"))) specifiers.
    613   ///
    614   /// In this case, "foo" is passed in to be checked.  If the section
    615   /// specifier is invalid, the backend should return a non-empty string
    616   /// that indicates the problem.
    617   ///
    618   /// This hook is a simple quality of implementation feature to catch errors
    619   /// and give good diagnostics in cases when the assembler or code generator
    620   /// would otherwise reject the section specifier.
    621   ///
    622   virtual std::string isValidSectionSpecifier(StringRef SR) const {
    623     return "";
    624   }
    625 
    626   /// \brief Set forced language options.
    627   ///
    628   /// Apply changes to the target information with respect to certain
    629   /// language options which change the target configuration.
    630   virtual void adjust(const LangOptions &Opts);
    631 
    632   /// \brief Get the default set of target features for the CPU;
    633   /// this should include all legal feature strings on the target.
    634   virtual void getDefaultFeatures(llvm::StringMap<bool> &Features) const {
    635   }
    636 
    637   /// \brief Get the ABI currently in use.
    638   virtual StringRef getABI() const { return StringRef(); }
    639 
    640   /// \brief Get the C++ ABI currently in use.
    641   TargetCXXABI getCXXABI() const {
    642     return TheCXXABI;
    643   }
    644 
    645   /// \brief Target the specified CPU.
    646   ///
    647   /// \return  False on error (invalid CPU name).
    648   virtual bool setCPU(const std::string &Name) {
    649     return false;
    650   }
    651 
    652   /// \brief Use the specified ABI.
    653   ///
    654   /// \return False on error (invalid ABI name).
    655   virtual bool setABI(const std::string &Name) {
    656     return false;
    657   }
    658 
    659   /// \brief Use the specified unit for FP math.
    660   ///
    661   /// \return False on error (invalid unit name).
    662   virtual bool setFPMath(StringRef Name) {
    663     return false;
    664   }
    665 
    666   /// \brief Use this specified C++ ABI.
    667   ///
    668   /// \return False on error (invalid C++ ABI name).
    669   bool setCXXABI(llvm::StringRef name) {
    670     TargetCXXABI ABI;
    671     if (!ABI.tryParse(name)) return false;
    672     return setCXXABI(ABI);
    673   }
    674 
    675   /// \brief Set the C++ ABI to be used by this implementation.
    676   ///
    677   /// \return False on error (ABI not valid on this target)
    678   virtual bool setCXXABI(TargetCXXABI ABI) {
    679     TheCXXABI = ABI;
    680     return true;
    681   }
    682 
    683   /// \brief Enable or disable a specific target feature;
    684   /// the feature name must be valid.
    685   virtual void setFeatureEnabled(llvm::StringMap<bool> &Features,
    686                                  StringRef Name,
    687                                  bool Enabled) const {
    688     Features[Name] = Enabled;
    689   }
    690 
    691   /// \brief Perform initialization based on the user configured
    692   /// set of features (e.g., +sse4).
    693   ///
    694   /// The list is guaranteed to have at most one entry per feature.
    695   ///
    696   /// The target may modify the features list, to change which options are
    697   /// passed onwards to the backend.
    698   ///
    699   /// \return  False on error.
    700   virtual bool handleTargetFeatures(std::vector<std::string> &Features,
    701                                     DiagnosticsEngine &Diags) {
    702     return true;
    703   }
    704 
    705   /// \brief Determine whether the given target has the given feature.
    706   virtual bool hasFeature(StringRef Feature) const {
    707     return false;
    708   }
    709 
    710   // \brief Returns maximal number of args passed in registers.
    711   unsigned getRegParmMax() const {
    712     assert(RegParmMax < 7 && "RegParmMax value is larger than AST can handle");
    713     return RegParmMax;
    714   }
    715 
    716   /// \brief Whether the target supports thread-local storage.
    717   bool isTLSSupported() const {
    718     return TLSSupported;
    719   }
    720 
    721   /// \brief Return true if {|} are normal characters in the asm string.
    722   ///
    723   /// If this returns false (the default), then {abc|xyz} is syntax
    724   /// that says that when compiling for asm variant #0, "abc" should be
    725   /// generated, but when compiling for asm variant #1, "xyz" should be
    726   /// generated.
    727   bool hasNoAsmVariants() const {
    728     return NoAsmVariants;
    729   }
    730 
    731   /// \brief Return the register number that __builtin_eh_return_regno would
    732   /// return with the specified argument.
    733   virtual int getEHDataRegisterNumber(unsigned RegNo) const {
    734     return -1;
    735   }
    736 
    737   /// \brief Return the section to use for C++ static initialization functions.
    738   virtual const char *getStaticInitSectionSpecifier() const {
    739     return nullptr;
    740   }
    741 
    742   const LangAS::Map &getAddressSpaceMap() const {
    743     return *AddrSpaceMap;
    744   }
    745 
    746   /// \brief Retrieve the name of the platform as it is used in the
    747   /// availability attribute.
    748   StringRef getPlatformName() const { return PlatformName; }
    749 
    750   /// \brief Retrieve the minimum desired version of the platform, to
    751   /// which the program should be compiled.
    752   VersionTuple getPlatformMinVersion() const { return PlatformMinVersion; }
    753 
    754   bool isBigEndian() const { return BigEndian; }
    755 
    756   enum CallingConvMethodType {
    757     CCMT_Unknown,
    758     CCMT_Member,
    759     CCMT_NonMember
    760   };
    761 
    762   /// \brief Gets the default calling convention for the given target and
    763   /// declaration context.
    764   virtual CallingConv getDefaultCallingConv(CallingConvMethodType MT) const {
    765     // Not all targets will specify an explicit calling convention that we can
    766     // express.  This will always do the right thing, even though it's not
    767     // an explicit calling convention.
    768     return CC_C;
    769   }
    770 
    771   enum CallingConvCheckResult {
    772     CCCR_OK,
    773     CCCR_Warning
    774   };
    775 
    776   /// \brief Determines whether a given calling convention is valid for the
    777   /// target. A calling convention can either be accepted, produce a warning
    778   /// and be substituted with the default calling convention, or (someday)
    779   /// produce an error (such as using thiscall on a non-instance function).
    780   virtual CallingConvCheckResult checkCallingConvention(CallingConv CC) const {
    781     switch (CC) {
    782       default:
    783         return CCCR_Warning;
    784       case CC_C:
    785         return CCCR_OK;
    786     }
    787   }
    788 
    789 protected:
    790   virtual uint64_t getPointerWidthV(unsigned AddrSpace) const {
    791     return PointerWidth;
    792   }
    793   virtual uint64_t getPointerAlignV(unsigned AddrSpace) const {
    794     return PointerAlign;
    795   }
    796   virtual enum IntType getPtrDiffTypeV(unsigned AddrSpace) const {
    797     return PtrDiffType;
    798   }
    799   virtual void getGCCRegNames(const char * const *&Names,
    800                               unsigned &NumNames) const = 0;
    801   virtual void getGCCRegAliases(const GCCRegAlias *&Aliases,
    802                                 unsigned &NumAliases) const = 0;
    803   virtual void getGCCAddlRegNames(const AddlRegName *&Addl,
    804                                   unsigned &NumAddl) const {
    805     Addl = nullptr;
    806     NumAddl = 0;
    807   }
    808   virtual bool validateAsmConstraint(const char *&Name,
    809                                      TargetInfo::ConstraintInfo &info) const= 0;
    810 };
    811 
    812 }  // end namespace clang
    813 
    814 #endif
    815