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, 1992, 1994, 1997, 1998, 2000, 2003, 2004, 2005
   4    Free Software Foundation, Inc.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 2, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING.  If not, write to the Free
  20 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  21 02110-1301, USA.  */
  22
  23
  24 /* This file defines all the MACHINE MODES used by GCC.
  25
  26    A machine mode specifies a size and format of data
  27    at the machine level.
  28
  29    Each RTL expression has a machine mode.
  30
  31    At the syntax tree level, each ..._TYPE and each ..._DECL node
  32    has a machine mode which describes data of that type or the
  33    data of the variable declared.  */
  34
  35 /* This file is included by the genmodes program.  Its text is the
  36    body of a function.  Do not rely on this, it will change in the
  37    future.
  38
  39    The following statements can be used in this file -- all have
  40    the form of a C macro call.  In their arguments:
  41
  42    A CLASS argument must be one of the constants defined in
  43    mode-classes.def, less the leading MODE_ prefix; some statements
  44    that take CLASS arguments have restrictions on which classes are
  45    acceptable.  For instance, INT.
  46
  47    A MODE argument must be the printable name of a machine mode,
  48    without quotation marks or trailing "mode".  For instance, SI.
  49
  50    A PRECISION, BYTESIZE, or COUNT argument must be a positive integer
  51    constant.
  52
  53    A FORMAT argument must be one of the real_mode_format structures
  54    declared in real.h, or else a literal 0.  Do not put a leading &
  55    on the argument.
  56
  57    An EXPR argument must be a syntactically valid C expression.
  58    If an EXPR contains commas, you may need to write an extra pair of
  59    parentheses around it, so it appears to be a single argument to the
  60    statement.
  61
  62    This file defines only those modes which are of use on almost all
  63    machines.  Other modes can be defined in the target-specific
  64    mode definition file, config/ARCH/ARCH-modes.def.
  65
  66    Order matters in this file in so far as statements which refer to
  67    other modes must appear after the modes they refer to.  However,
  68    statements which do not refer to other modes may appear in any
  69    order.
  70
  71      RANDOM_MODE (MODE);
  72         declares MODE to be of class RANDOM.
  73
  74      CC_MODE (MODE);
  75         declares MODE to be of class CC.
  76
  77      INT_MODE (MODE, BYTESIZE);
  78         declares MODE to be of class INT and BYTESIZE bytes wide.
  79         All of the bits of its representation are significant.
  80
  81      FRACTIONAL_INT_MODE (MODE, PRECISION, BYTESIZE);
  82         declares MODE to be of class INT, BYTESIZE bytes wide in
  83         storage, but with only PRECISION significant bits.
  84
  85      FLOAT_MODE (MODE, BYTESIZE, FORMAT);
  86         declares MODE to be of class FLOAT and BYTESIZE bytes wide,
  87         using floating point format FORMAT.
  88         All of the bits of its representation are significant.
  89
  90      DECIMAL FLOAT_MODE (MODE, BYTESIZE);
  91         declares MODE to be of class DECIMAL_FLOAT and BYTESIZE bytes
  92         wide.  All of the bits of its representation are significant.
  93
  94      FRACTIONAL_FLOAT_MODE (MODE, PRECISION, BYTESIZE, FORMAT);
  95         declares MODE to be of class FLOAT, BYTESIZE bytes wide in
  96         storage, but with only PRECISION significant bits, using
  97         floating point format FORMAT.
  98
  99      RESET_FLOAT_FORMAT (MODE, FORMAT);
 100         changes the format of MODE, which must be class FLOAT,
 101         to FORMAT.  Use in an ARCH-modes.def to reset the format
 102         of one of the float modes defined in this file.
 103
 104      PARTIAL_INT_MODE (MODE);
 105         declares a mode of class PARTIAL_INT with the same size as
 106         MODE (which must be an INT mode).  The name of the new mode
 107         is made by prefixing a P to the name MODE.  This statement
 108         may grow a PRECISION argument in the future.
 109
 110      VECTOR_MODE (CLASS, MODE, COUNT);
 111         Declare a vector mode whose component mode is MODE (of class
 112         CLASS) with COUNT components.  CLASS must be INT or FLOAT.
 113         The name of the vector mode takes the form VnX where n is
 114         COUNT in decimal and X is MODE.
 115
 116      VECTOR_MODES (CLASS, WIDTH);
 117         For all modes presently declared in class CLASS, construct
 118         corresponding vector modes having width WIDTH.  Modes whose
 119         byte sizes do not evenly divide WIDTH are ignored, as are
 120         modes that would produce vector modes with only one component,
 121         and modes smaller than one byte (if CLASS is INT) or smaller
 122         than two bytes (if CLASS is FLOAT).  CLASS must be INT or
 123         FLOAT.  The names follow the same rule as VECTOR_MODE uses.
 124
 125      COMPLEX_MODES (CLASS);
 126         For all modes presently declared in class CLASS, construct
 127         corresponding complex modes.  Modes smaller than one byte
 128         are ignored.  For FLOAT modes, the names are derived by
 129         replacing the 'F' in the mode name with a 'C'.  (It is an
 130         error if there is no 'F'.  For INT modes, the names are
 131         derived by prefixing a C to the name.
 132
 133      ADJUST_BYTESIZE (MODE, EXPR);
 134      ADJUST_ALIGNMENT (MODE, EXPR);
 135      ADJUST_FLOAT_FORMAT (MODE, EXPR);
 136         Arrange for the byte size, alignment, or floating point format
 137         of MODE to be adjustable at run time.  EXPR will be executed
 138         once after processing all command line options, and should
 139         evaluate to the desired byte size, alignment, or format.
 140
 141         Unlike a FORMAT argument, if you are adjusting a float format
 142         you must put an & in front of the name of each format structure.
 143
 144    Note: If a mode is ever made which is more than 255 bytes wide,
 145    machmode.h and genmodes.c will have to be changed to allocate
 146    more space for the mode_size and mode_alignment arrays.  */
 147
 148 /* VOIDmode is used when no mode needs to be specified,
 149    as for example on CONST_INT RTL expressions.  */
 150 RANDOM_MODE (VOID);
 151
 152 /* BLKmode is used for structures, arrays, etc.
 153    that fit no more specific mode.  */
 154 RANDOM_MODE (BLK);
 155
 156 /* Single bit mode used for booleans.  */
 157 FRACTIONAL_INT_MODE (BI, 1, 1);
 158
 159 /* Basic integer modes.  We go up to TI in generic code (128 bits).
 160    The name OI is reserved for a 256-bit type (needed by some back ends).
 161    FIXME TI shouldn't be generically available either.  */
 162 INT_MODE (QI, 1);
 163 INT_MODE (HI, 2);
 164 INT_MODE (SI, 4);
 165 INT_MODE (DI, 8);
 166 INT_MODE (TI, 16);
 167
 168 /* No partial integer modes are defined by default.  */
 169
 170 /* Basic floating point modes.  SF and DF are the only modes provided
 171    by default.  The names QF, HF, XF, and TF are reserved for targets
 172    that need 1-word, 2-word, 80-bit, or 128-bit float types respectively.
 173
 174    These are the IEEE mappings.  They can be overridden with
 175    RESET_FLOAT_FORMAT or at runtime (in OVERRIDE_OPTIONS).  */
 176
 177 FLOAT_MODE (SF, 4, ieee_single_format);
 178 FLOAT_MODE (DF, 8, ieee_double_format);
 179
 180 /* Basic CC modes.
 181    FIXME define this only for targets that need it.  */
 182 CC_MODE (CC);
 183
 184 /* Allow the target to specify additional modes of various kinds.  */
 185 #if HAVE_EXTRA_MODES
 186 # include EXTRA_MODES_FILE
 187 #endif
 188
 189 /* Complex modes.  */
 190 COMPLEX_MODES (INT);
 191 COMPLEX_MODES (FLOAT);
 192
 193 /* Decimal floating point modes.  */
 194 DECIMAL_FLOAT_MODE (SD, 4, decimal_single_format);
 195 DECIMAL_FLOAT_MODE (DD, 8, decimal_double_format);
 196 DECIMAL_FLOAT_MODE (TD, 16, decimal_quad_format);
 197
 198 /* The symbol Pmode stands for one of the above machine modes (usually SImode).
 199    The tm.h file specifies which one.  It is not a distinct mode.  */
 200
 201 /*
 202 Local variables:
 203 mode:c
 204 version-control: t
 205 End:
 206 */