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    2007  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 3, 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 COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22
  23 /* This file defines all the MACHINE MODES used by GCC.
  24
  25    A machine mode specifies a size and format of data
  26    at the machine level.
  27
  28    Each RTL expression has a machine mode.
  29
  30    At the syntax tree level, each ..._TYPE and each ..._DECL node
  31    has a machine mode which describes data of that type or the
  32    data of the variable declared.  */
  33
  34 /* This file is included by the genmodes program.  Its text is the
  35    body of a function.  Do not rely on this, it will change in the
  36    future.
  37
  38    The following statements can be used in this file -- all have
  39    the form of a C macro call.  In their arguments:
  40
  41    A CLASS argument must be one of the constants defined in
  42    mode-classes.def, less the leading MODE_ prefix; some statements
  43    that take CLASS arguments have restrictions on which classes are
  44    acceptable.  For instance, INT.
  45
  46    A MODE argument must be the printable name of a machine mode,
  47    without quotation marks or trailing "mode".  For instance, SI.
  48
  49    A PRECISION, BYTESIZE, or COUNT argument must be a positive integer
  50    constant.
  51
  52    A FORMAT argument must be one of the real_mode_format structures
  53    declared in real.h, or else a literal 0.  Do not put a leading &
  54    on the argument.
  55
  56    An EXPR argument must be a syntactically valid C expression.
  57    If an EXPR contains commas, you may need to write an extra pair of
  58    parentheses around it, so it appears to be a single argument to the
  59    statement.
  60
  61    This file defines only those modes which are of use on almost all
  62    machines.  Other modes can be defined in the target-specific
  63    mode definition file, config/ARCH/ARCH-modes.def.
  64
  65    Order matters in this file in so far as statements which refer to
  66    other modes must appear after the modes they refer to.  However,
  67    statements which do not refer to other modes may appear in any
  68    order.
  69
  70      RANDOM_MODE (MODE);
  71         declares MODE to be of class RANDOM.
  72
  73      CC_MODE (MODE);
  74         declares MODE to be of class CC.
  75
  76      INT_MODE (MODE, BYTESIZE);
  77         declares MODE to be of class INT and BYTESIZE bytes wide.
  78         All of the bits of its representation are significant.
  79
  80      FRACTIONAL_INT_MODE (MODE, PRECISION, BYTESIZE);
  81         declares MODE to be of class INT, BYTESIZE bytes wide in
  82         storage, but with only PRECISION significant bits.
  83
  84      FLOAT_MODE (MODE, BYTESIZE, FORMAT);
  85         declares MODE to be of class FLOAT and BYTESIZE bytes wide,
  86         using floating point format FORMAT.
  87         All of the bits of its representation are significant.
  88
  89      DECIMAL FLOAT_MODE (MODE, BYTESIZE);
  90         declares MODE to be of class DECIMAL_FLOAT and BYTESIZE bytes
  91         wide.  All of the bits of its representation are significant.
  92
  93      FRACTIONAL_FLOAT_MODE (MODE, PRECISION, BYTESIZE, FORMAT);
  94         declares MODE to be of class FLOAT, BYTESIZE bytes wide in
  95         storage, but with only PRECISION significant bits, using
  96         floating point format FORMAT.
  97
  98      RESET_FLOAT_FORMAT (MODE, FORMAT);
  99         changes the format of MODE, which must be class FLOAT,
 100         to FORMAT.  Use in an ARCH-modes.def to reset the format
 101         of one of the float modes defined in this file.
 102
 103      PARTIAL_INT_MODE (MODE);
 104         declares a mode of class PARTIAL_INT with the same size as
 105         MODE (which must be an INT mode).  The name of the new mode
 106         is made by prefixing a P to the name MODE.  This statement
 107         may grow a PRECISION argument in the future.
 108
 109      VECTOR_MODE (CLASS, MODE, COUNT);
 110         Declare a vector mode whose component mode is MODE (of class
 111         CLASS) with COUNT components.  CLASS must be INT or FLOAT.
 112         The name of the vector mode takes the form VnX where n is
 113         COUNT in decimal and X is MODE.
 114
 115      VECTOR_MODES (CLASS, WIDTH);
 116         For all modes presently declared in class CLASS, construct
 117         corresponding vector modes having width WIDTH.  Modes whose
 118         byte sizes do not evenly divide WIDTH are ignored, as are
 119         modes that would produce vector modes with only one component,
 120         and modes smaller than one byte (if CLASS is INT) or smaller
 121         than two bytes (if CLASS is FLOAT).  CLASS must be INT or
 122         FLOAT.  The names follow the same rule as VECTOR_MODE uses.
 123
 124      COMPLEX_MODES (CLASS);
 125         For all modes presently declared in class CLASS, construct
 126         corresponding complex modes.  Modes smaller than one byte
 127         are ignored.  For FLOAT modes, the names are derived by
 128         replacing the 'F' in the mode name with a 'C'.  (It is an
 129         error if there is no 'F'.  For INT modes, the names are
 130         derived by prefixing a C to the name.
 131
 132      ADJUST_BYTESIZE (MODE, EXPR);
 133      ADJUST_ALIGNMENT (MODE, EXPR);
 134      ADJUST_FLOAT_FORMAT (MODE, EXPR);
 135         Arrange for the byte size, alignment, or floating point format
 136         of MODE to be adjustable at run time.  EXPR will be executed
 137         once after processing all command line options, and should
 138         evaluate to the desired byte size, alignment, or format.
 139
 140         Unlike a FORMAT argument, if you are adjusting a float format
 141         you must put an & in front of the name of each format structure.
 142
 143    Note: If a mode is ever made which is more than 255 bytes wide,
 144    machmode.h and genmodes.c will have to be changed to allocate
 145    more space for the mode_size and mode_alignment arrays.  */
 146
 147 /* VOIDmode is used when no mode needs to be specified,
 148    as for example on CONST_INT RTL expressions.  */
 149 RANDOM_MODE (VOID);
 150
 151 /* BLKmode is used for structures, arrays, etc.
 152    that fit no more specific mode.  */
 153 RANDOM_MODE (BLK);
 154
 155 /* Single bit mode used for booleans.  */
 156 FRACTIONAL_INT_MODE (BI, 1, 1);
 157
 158 /* Basic integer modes.  We go up to TI in generic code (128 bits).
 159    The name OI is reserved for a 256-bit type (needed by some back ends).
 160    FIXME TI shouldn't be generically available either.  */
 161 INT_MODE (QI, 1);
 162 INT_MODE (HI, 2);
 163 INT_MODE (SI, 4);
 164 INT_MODE (DI, 8);
 165 INT_MODE (TI, 16);
 166
 167 /* No partial integer modes are defined by default.  */
 168
 169 /* Basic floating point modes.  SF and DF are the only modes provided
 170    by default.  The names QF, HF, XF, and TF are reserved for targets
 171    that need 1-word, 2-word, 80-bit, or 128-bit float types respectively.
 172
 173    These are the IEEE mappings.  They can be overridden with
 174    RESET_FLOAT_FORMAT or at runtime (in OVERRIDE_OPTIONS).  */
 175
 176 FLOAT_MODE (SF, 4, ieee_single_format);
 177 FLOAT_MODE (DF, 8, ieee_double_format);
 178
 179 /* Basic CC modes.
 180    FIXME define this only for targets that need it.  */
 181 CC_MODE (CC);
 182
 183 /* Allow the target to specify additional modes of various kinds.  */
 184 #if HAVE_EXTRA_MODES
 185 # include EXTRA_MODES_FILE
 186 #endif
 187
 188 /* Complex modes.  */
 189 COMPLEX_MODES (INT);
 190 COMPLEX_MODES (FLOAT);
 191
 192 /* Decimal floating point modes.  */
 193 DECIMAL_FLOAT_MODE (SD, 4, decimal_single_format);
 194 DECIMAL_FLOAT_MODE (DD, 8, decimal_double_format);
 195 DECIMAL_FLOAT_MODE (TD, 16, decimal_quad_format);
 196
 197 /* The symbol Pmode stands for one of the above machine modes (usually SImode).
 198    The tm.h file specifies which one.  It is not a distinct mode.  */
 199
 200 /*
 201 Local variables:
 202 mode:c
 203 version-control: t
 204 End:
 205 */