gcc/ada/set_targ.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             S E T _ T A R G                              --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 2013-2023, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
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  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT; see file COPYING3.  If not, go to --
  19 -- http://www.gnu.org/licenses for a complete copy of the license.          --
  20 --                                                                          --
  21 -- GNAT was originally developed  by the GNAT team at  New York University. --
  22 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  23 --                                                                          --
  24 ------------------------------------------------------------------------------
  25
  26 --  This package handles setting target dependent parameters. If the -gnatet
  27 --  switch is not set, then these values are taken from the back end (via the
  28 --  routines in Get_Targ, and the enumerate_modes routine in misc.cc). If the
  29 --  switch is set, then the values are read from the target.atp file in the
  30 --  current directory (usually written with the Write_Target_Dependent_Values
  31 --  procedure defined in this package).
  32
  33 --  Note that all these values return sizes of C types with corresponding
  34 --  names. This allows GNAT to define the corresponding Ada types to have
  35 --  the same representation. There is one exception: the representation
  36 --  of Wide_Character_Type uses twice the size of a C char, instead of the
  37 --  size of wchar_t, since this corresponds to expected Ada usage.
  38
  39 with Stand; use Stand;
  40 with Types; use Types;
  41
  42 package Set_Targ is
  43
  44    -----------------------------
  45    -- Target-Dependent Values --
  46    -----------------------------
  47
  48    --  The following is a table of target dependent values. In normal operation
  49    --  these values are set by calling the appropriate C backend routines that
  50    --  interface to back end routines that determine target characteristics.
  51
  52    --  If the -gnateT switch is used, then any values that are read from the
  53    --  file target.atp in the current directory overwrite values set from the
  54    --  back end. This is used by tools other than the compiler, e.g. to do
  55    --  semantic analysis of programs that will run on some other target than
  56    --  the machine on which the tool is run.
  57
  58    --  Note: fields marked with a question mark are boolean fields, where a
  59    --  value of 0 is False, and a value of 1 is True.
  60
  61    Bits_BE                    : Nat; -- Bits stored big-endian?
  62    Bits_Per_Unit              : Pos; -- Bits in a storage unit
  63    Bits_Per_Word              : Pos; -- Bits in a word
  64    Bytes_BE                   : Nat; -- Bytes stored big-endian?
  65    Char_Size                  : Pos; -- Standard.Character'Size
  66    Double_Float_Alignment     : Nat; -- Alignment of double float
  67    Double_Scalar_Alignment    : Nat; -- Alignment of double length scalar
  68    Double_Size                : Pos; -- Standard.Long_Float'Size
  69    Float_Size                 : Pos; -- Standard.Float'Size
  70    Float_Words_BE             : Nat; -- Float words stored big-endian?
  71    Int_Size                   : Pos; -- Standard.Integer'Size
  72    Long_Double_Size           : Pos; -- Standard.Long_Long_Float'Size
  73    Long_Long_Long_Size        : Pos; -- Standard.Long_Long_Long_Integer'Size
  74    Long_Long_Size             : Pos; -- Standard.Long_Long_Integer'Size
  75    Long_Size                  : Pos; -- Standard.Long_Integer'Size
  76    Maximum_Alignment          : Pos; -- Maximum permitted alignment
  77    Max_Unaligned_Field        : Pos; -- Kept only for backward compatibility
  78    Pointer_Size               : Pos; -- System.Address'Size
  79    Short_Enums                : Nat; -- Foreign enums use short size?
  80    Short_Size                 : Pos; -- Standard.Short_Integer'Size
  81    Strict_Alignment           : Nat; -- Strict alignment?
  82    System_Allocator_Alignment : Nat; -- Alignment for malloc calls
  83    Wchar_T_Size               : Pos; -- Interfaces.C.wchar_t'Size
  84    Words_BE                   : Nat; -- Words stored big-endian?
  85
  86    -------------------------------------
  87    -- Registered Floating-Point Types --
  88    -------------------------------------
  89
  90    --  This table contains the list of modes supported by the back-end as
  91    --  provided by the back end routine enumerate_modes in misc.cc. Note that
  92    --  we only store floating-point modes (see Register_Float_Type).
  93
  94    type FPT_Mode_Entry is record
  95       NAME      : String_Ptr;     -- Name of mode (no null character at end)
  96       DIGS      : Natural;        -- Digits for floating-point type
  97       FLOAT_REP : Float_Rep_Kind; -- Float representation
  98       PRECISION : Natural;        -- Precision in bits
  99       SIZE      : Natural;        -- Size in bits
 100       ALIGNMENT : Natural;        -- Alignment in bits
 101    end record;
 102
 103    FPT_Mode_Table : array (1 .. 1000) of FPT_Mode_Entry;
 104    Num_FPT_Modes  : Natural := 0;
 105    --  Table containing the supported modes and number of entries
 106
 107    -----------------
 108    -- Subprograms --
 109    -----------------
 110
 111    subtype S_Float_Types is
 112      Standard_Entity_Type range S_Short_Float .. S_Long_Long_Float;
 113
 114    function C_Type_For (T : S_Float_Types) return String;
 115    --  Return the name of a C type supported by the back-end and suitable as
 116    --  a basis to construct the standard Ada floating point type identified by
 117    --  T. This is used as a common ground to feed both ttypes values and the
 118    --  GNAT tree nodes for the standard floating point types.
 119
 120    procedure Write_Target_Dependent_Values;
 121    --  This routine writes the file target.atp in the current directory with
 122    --  the values of the global target parameters as listed above, and as set
 123    --  by prior calls to Initialize/Read_Target_Dependent_Values. The format
 124    --  of the target.atp file is as follows
 125    --
 126    --    First come the values of the variables defined in this spec:
 127    --
 128    --      One line per value
 129    --
 130    --        name  value
 131    --
 132    --      where name is the name of the parameter, spelled out in full,
 133    --      and cased as in the above list, and value is an unsigned decimal
 134    --      integer. Two or more blanks separates the name from the value.
 135    --
 136    --      All the variables must be present, in alphabetical order (i.e. the
 137    --      same order as the declarations in this spec).
 138    --
 139    --   Then there is a blank line to separate the two parts of the file. Then
 140    --   come the lines showing the floating-point types to be registered.
 141    --
 142    --     One line per registered mode
 143    --
 144    --       name  digs float_rep precision alignment
 145    --
 146    --     where name is the string name of the type (which can have
 147    --     single spaces embedded in the name (e.g. long double). The
 148    --     name is followed by at least two blanks. The following fields
 149    --     are as described above for a Mode_Entry (where float_rep is
 150    --     I for IEEE-754-Binary, which is the only Float_Rep_Kind
 151    --     currently supported), fields are separated by at least one
 152    --     blank, and a LF character immediately follows the alignment
 153    --     field.
 154    --
 155    --     ??? We do not write the size for backward compatibility reasons,
 156    --     which means that target.atp will not be a complete description for
 157    --     the very peculiar cases where the size cannot be computed from the
 158    --     precision and the alignment by the formula:
 159    --
 160    --       size := (precision + alignment - 1) / alignment * alignment
 161
 162 end Set_Targ;