gcc/machmode.def

   1 /* This file contains the definitions and documentation for the
   2    machine modes used in the GNU compiler.
   3    Copyright (C) 1987-2019 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21
  22 /* This file defines all the MACHINE MODES used by GCC.
  23
  24    A machine mode specifies a size and format of data
  25    at the machine level.
  26
  27    Each RTL expression has a machine mode.
  28
  29    At the syntax tree level, each ..._TYPE and each ..._DECL node
  30    has a machine mode which describes data of that type or the
  31    data of the variable declared.  */
  32
  33 /* This file is included by the genmodes program.  Its text is the
  34    body of a function.  Do not rely on this, it will change in the
  35    future.
  36
  37    The following statements can be used in this file -- all have
  38    the form of a C macro call.  In their arguments:
  39
  40    A CLASS argument must be one of the constants defined in
  41    mode-classes.def, less the leading MODE_ prefix; some statements
  42    that take CLASS arguments have restrictions on which classes are
  43    acceptable.  For instance, INT.
  44
  45    A MODE argument must be the printable name of a machine mode,
  46    without quotation marks or trailing "mode".  For instance, SI.
  47
  48    A PRECISION, BYTESIZE, or COUNT argument must be a positive integer
  49    constant.
  50
  51    A FORMAT argument must be one of the real_mode_format structures
  52    declared in real.h, or else a literal 0.  Do not put a leading &
  53    on the argument.
  54
  55    An EXPR argument must be a syntactically valid C expression.
  56    If an EXPR contains commas, you may need to write an extra pair of
  57    parentheses around it, so it appears to be a single argument to the
  58    statement.
  59
  60    This file defines only those modes which are of use on almost all
  61    machines.  Other modes can be defined in the target-specific
  62    mode definition file, config/ARCH/ARCH-modes.def.
  63
  64    Order matters in this file in so far as statements which refer to
  65    other modes must appear after the modes they refer to.  However,
  66    statements which do not refer to other modes may appear in any
  67    order.
  68
  69      RANDOM_MODE (MODE);
  70         declares MODE to be of class RANDOM.
  71
  72      CC_MODE (MODE);
  73         declares MODE to be of class CC.
  74
  75      INT_MODE (MODE, BYTESIZE);
  76         declares MODE to be of class INT and BYTESIZE bytes wide.
  77         All of the bits of its representation are significant.
  78
  79      FRACTIONAL_INT_MODE (MODE, PRECISION, BYTESIZE);
  80         declares MODE to be of class INT, BYTESIZE bytes wide in
  81         storage, but with only PRECISION significant bits.
  82
  83      FLOAT_MODE (MODE, BYTESIZE, FORMAT);
  84         declares MODE to be of class FLOAT and BYTESIZE bytes wide,
  85         using floating point format FORMAT.
  86         All of the bits of its representation are significant.
  87
  88      FRACTIONAL_FLOAT_MODE (MODE, PRECISION, BYTESIZE, FORMAT);
  89         declares MODE to be of class FLOAT, BYTESIZE bytes wide in
  90         storage, but with only PRECISION significant bits, using
  91         floating point format FORMAT.
  92
  93      DECIMAL_FLOAT_MODE (MODE, BYTESIZE, FORMAT);
  94         declares MODE to be of class DECIMAL_FLOAT and BYTESIZE bytes
  95         wide.  All of the bits of its representation are significant.
  96
  97      FRACTIONAL_DECIMAL_FLOAT_MODE (MODE, BYTESIZE, FORMAT);
  98         declares MODE to be of class DECIMAL_FLOAT and BYTESIZE bytes
  99         wide.  All of the bits of its representation are significant.
 100
 101      FRACT_MODE (MODE, BYTESIZE, FBIT);
 102         declares MODE to be of class FRACT and BYTESIZE bytes wide
 103         with FBIT fractional bits.  There may be padding bits.
 104
 105      UFRACT_MODE (MODE, BYTESIZE, FBIT);
 106         declares MODE to be of class UFRACT and BYTESIZE bytes wide
 107         with FBIT fractional bits.  There may be padding bits.
 108
 109      ACCUM_MODE (MODE, BYTESIZE, IBIT, FBIT);
 110         declares MODE to be of class ACCUM and BYTESIZE bytes wide
 111         with IBIT integral bits and FBIT fractional bits.
 112         There may be padding bits.
 113
 114      UACCUM_MODE (MODE, BYTESIZE, IBIT, FBIT);
 115         declares MODE to be of class UACCUM and BYTESIZE bytes wide
 116         with IBIT integral bits and FBIT fractional bits.
 117         There may be padding bits.
 118
 119      RESET_FLOAT_FORMAT (MODE, FORMAT);
 120         changes the format of MODE, which must be class FLOAT,
 121         to FORMAT.  Use in an ARCH-modes.def to reset the format
 122         of one of the float modes defined in this file.
 123
 124      PARTIAL_INT_MODE (MODE, PRECISION, NAME);
 125         declares a mode of class PARTIAL_INT with the same size as
 126         MODE (which must be an INT mode) and precision PREC.
 127         Optionally, NAME is the new name of the mode.  NAME is the
 128         name of the mode.
 129
 130      VECTOR_MODE (CLASS, MODE, COUNT);
 131         Declare a vector mode whose component mode is MODE (of class
 132         CLASS) with COUNT components.  CLASS must be INT or FLOAT.
 133         The name of the vector mode takes the form VnX where n is
 134         COUNT in decimal and X is MODE.
 135
 136      VECTOR_MODES (CLASS, WIDTH);
 137         For all modes presently declared in class CLASS, construct
 138         corresponding vector modes having width WIDTH.  Modes whose
 139         byte sizes do not evenly divide WIDTH are ignored, as are
 140         modes that would produce vector modes with only one component,
 141         and modes smaller than one byte (if CLASS is INT) or smaller
 142         than two bytes (if CLASS is FLOAT).  CLASS must be INT or
 143         FLOAT.  The names follow the same rule as VECTOR_MODE uses.
 144
 145      VECTOR_MODES_WITH_PREFIX (PREFIX, CLASS, WIDTH);
 146         Like VECTOR_MODES, but start the mode names with PREFIX instead
 147         of the usual "V".
 148
 149      VECTOR_BOOL_MODE (NAME, COUNT, BYTESIZE)
 150         Create a vector mode called NAME that contains COUNT boolean
 151         elements and occupies BYTESIZE bytes in total.  Each boolean
 152         element occupies (COUNT * BITS_PER_UNIT) / BYTESIZE bits, with
 153         the element at index 0 occupying the lsb of the first byte in
 154         memory.  Only the lowest bit of each element is significant.
 155
 156      COMPLEX_MODES (CLASS);
 157         For all modes presently declared in class CLASS, construct
 158         corresponding complex modes.  Modes smaller than one byte
 159         are ignored.  For FLOAT modes, the names are derived by
 160         replacing the 'F' in the mode name with a 'C'.  (It is an
 161         error if there is no 'F'.  For INT modes, the names are
 162         derived by prefixing a C to the name.
 163
 164      ADJUST_BYTESIZE (MODE, EXPR);
 165      ADJUST_ALIGNMENT (MODE, EXPR);
 166      ADJUST_FLOAT_FORMAT (MODE, EXPR);
 167      ADJUST_IBIT (MODE, EXPR);
 168      ADJUST_FBIT (MODE, EXPR);
 169         Arrange for the byte size, alignment, floating point format, ibit,
 170         or fbit of MODE to be adjustable at run time.  EXPR will be executed
 171         once after processing all command line options, and should
 172         evaluate to the desired byte size, alignment, format, ibit or fbit.
 173
 174         Unlike a FORMAT argument, if you are adjusting a float format
 175         you must put an & in front of the name of each format structure.
 176
 177      ADJUST_NUNITS (MODE, EXPR);
 178         Like the above, but set the number of nunits of MODE to EXPR.
 179         This changes the size and precision of the mode in proportion
 180         to the change in the number of units; for example, doubling
 181         the number of units doubles the size and precision as well.
 182
 183    Note: If a mode is ever made which is more than 255 bytes wide,
 184    machmode.h and genmodes.c will have to be changed to allocate
 185    more space for the mode_size and mode_alignment arrays.  */
 186
 187 /* VOIDmode is used when no mode needs to be specified,
 188    as for example on CONST_INT RTL expressions.  */
 189 RANDOM_MODE (VOID);
 190
 191 /* BLKmode is used for structures, arrays, etc.
 192    that fit no more specific mode.  */
 193 RANDOM_MODE (BLK);
 194
 195 /* Single bit mode used for booleans.  */
 196 FRACTIONAL_INT_MODE (BI, 1, 1);
 197
 198 /* Basic integer modes.  We go up to TI in generic code (128 bits).
 199    TImode is needed here because the some front ends now genericly
 200    support __int128.  If the front ends decide to generically support
 201    larger types, then corresponding modes must be added here.  The
 202    name OI is reserved for a 256-bit type (needed by some back ends).
 203     */
 204 INT_MODE (QI, 1);
 205 INT_MODE (HI, 2);
 206 INT_MODE (SI, 4);
 207 INT_MODE (DI, 8);
 208 INT_MODE (TI, 16);
 209
 210 /* No partial integer modes are defined by default.  */
 211
 212 /* The target normally defines any target-specific __intN types and
 213    their modes, but __int128 for TImode is fairly common so define it
 214    here.  The type will not be created unless the target supports
 215    TImode.  */
 216
 217 INT_N (TI, 128);
 218
 219 /* Basic floating point modes.  SF and DF are the only modes provided
 220    by default.  The names QF, HF, XF, and TF are reserved for targets
 221    that need 1-word, 2-word, 80-bit, or 128-bit float types respectively.
 222
 223    These are the IEEE mappings.  They can be overridden with
 224    RESET_FLOAT_FORMAT or at runtime (in TARGET_OPTION_OVERRIDE).  */
 225
 226 FLOAT_MODE (SF, 4, ieee_single_format);
 227 FLOAT_MODE (DF, 8, ieee_double_format);
 228
 229 /* Basic CC modes.
 230    FIXME define this only for targets that need it.  */
 231 CC_MODE (CC);
 232
 233 /* Fixed-point modes.  */
 234 FRACT_MODE (QQ, 1, 7); /* s.7 */
 235 FRACT_MODE (HQ, 2, 15); /* s.15 */
 236 FRACT_MODE (SQ, 4, 31); /* s.31 */
 237 FRACT_MODE (DQ, 8, 63); /* s.63 */
 238 FRACT_MODE (TQ, 16, 127); /* s.127 */
 239
 240 UFRACT_MODE (UQQ, 1, 8); /* .8 */
 241 UFRACT_MODE (UHQ, 2, 16); /* .16 */
 242 UFRACT_MODE (USQ, 4, 32); /* .32 */
 243 UFRACT_MODE (UDQ, 8, 64); /* .64 */
 244 UFRACT_MODE (UTQ, 16, 128); /* .128 */
 245
 246 ACCUM_MODE (HA, 2, 8, 7); /* s8.7 */
 247 ACCUM_MODE (SA, 4, 16, 15); /* s16.15 */
 248 ACCUM_MODE (DA, 8, 32, 31); /* s32.31 */
 249 ACCUM_MODE (TA, 16, 64, 63); /* s64.63 */
 250
 251 UACCUM_MODE (UHA, 2, 8, 8); /* 8.8 */
 252 UACCUM_MODE (USA, 4, 16, 16); /* 16.16 */
 253 UACCUM_MODE (UDA, 8, 32, 32); /* 32.32 */
 254 UACCUM_MODE (UTA, 16, 64, 64); /* 64.64 */
 255
 256 /* Allow the target to specify additional modes of various kinds.  */
 257 #if HAVE_EXTRA_MODES
 258 # include EXTRA_MODES_FILE
 259 #endif
 260
 261 /* Complex modes.  */
 262 COMPLEX_MODES (INT);
 263 COMPLEX_MODES (PARTIAL_INT);
 264 COMPLEX_MODES (FLOAT);
 265
 266 /* Decimal floating point modes.  */
 267 DECIMAL_FLOAT_MODE (SD, 4, decimal_single_format);
 268 DECIMAL_FLOAT_MODE (DD, 8, decimal_double_format);
 269 DECIMAL_FLOAT_MODE (TD, 16, decimal_quad_format);
 270
 271 /* The symbol Pmode stands for one of the above machine modes (usually SImode).
 272    The tm.h file specifies which one.  It is not a distinct mode.  */
 273
 274 /*
 275 Local variables:
 276 mode:c
 277 version-control: t
 278 End:
 279 */