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, 59 Temple Place - Suite 330, Boston, MA
  21 02111-1307, 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      FRACTIONAL_FLOAT_MODE (MODE, PRECISION, BYTESIZE, FORMAT);
  91         declares MODE to be of class FLOAT, BYTESIZE bytes wide in
  92         storage, but with only PRECISION significant bits, using
  93         floating point format FORMAT.
  94
  95      RESET_FLOAT_FORMAT (MODE, FORMAT);
  96         changes the format of MODE, which must be class FLOAT,
  97         to FORMAT.  Use in an ARCH-modes.def to reset the format
  98         of one of the float modes defined in this file.
  99
 100      PARTIAL_INT_MODE (MODE);
 101         declares a mode of class PARTIAL_INT with the same size as
 102         MODE (which must be an INT mode).  The name of the new mode
 103         is made by prefixing a P to the name MODE.  This statement
 104         may grow a PRECISION argument in the future.
 105
 106      VECTOR_MODE (CLASS, MODE, COUNT);
 107         Declare a vector mode whose component mode is MODE (of class
 108         CLASS) with COUNT components.  CLASS must be INT or FLOAT.
 109         The name of the vector mode takes the form VnX where n is
 110         COUNT in decimal and X is MODE.
 111
 112      VECTOR_MODES (CLASS, WIDTH);
 113         For all modes presently declared in class CLASS, construct
 114         corresponding vector modes having width WIDTH.  Modes whose
 115         byte sizes do not evenly divide WIDTH are ignored, as are
 116         modes that would produce vector modes with only one component,
 117         and modes smaller than one byte (if CLASS is INT) or smaller
 118         than two bytes (if CLASS is FLOAT).  CLASS must be INT or
 119         FLOAT.  The names follow the same rule as VECTOR_MODE uses.
 120
 121      COMPLEX_MODES (CLASS);
 122         For all modes presently declared in class CLASS, construct
 123         corresponding complex modes.  Modes smaller than one byte
 124         are ignored.  For FLOAT modes, the names are derived by
 125         replacing the 'F' in the mode name with a 'C'.  (It is an
 126         error if there is no 'F'.  For INT modes, the names are
 127         derived by prefixing a C to the name.
 128
 129      ADJUST_BYTESIZE (MODE, EXPR);
 130      ADJUST_ALIGNMENT (MODE, EXPR);
 131      ADJUST_FLOAT_FORMAT (MODE, EXPR);
 132         Arrange for the byte size, alignment, or floating point format
 133         of MODE to be adjustable at run time.  EXPR will be executed
 134         once after processing all command line options, and should
 135         evaluate to the desired byte size, alignment, or format.
 136
 137         Unlike a FORMAT argument, if you are adjusting a float format
 138         you must put an & in front of the name of each format structure.
 139
 140    Note: If a mode is ever made which is more than 255 bytes wide,
 141    machmode.h and genmodes.c will have to be changed to allocate
 142    more space for the mode_size and mode_alignment arrays.  */
 143
 144 /* VOIDmode is used when no mode needs to be specified,
 145    as for example on CONST_INT RTL expressions.  */
 146 RANDOM_MODE (VOID);
 147
 148 /* BLKmode is used for structures, arrays, etc.
 149    that fit no more specific mode.  */
 150 RANDOM_MODE (BLK);
 151
 152 /* Single bit mode used for booleans.  */
 153 FRACTIONAL_INT_MODE (BI, 1, 1);
 154
 155 /* Basic integer modes.  We go up to TI in generic code (128 bits).
 156    The name OI is reserved for a 256-bit type (needed by some back ends).
 157    FIXME TI shouldn't be generically available either.  */
 158 INT_MODE (QI, 1);
 159 INT_MODE (HI, 2);
 160 INT_MODE (SI, 4);
 161 INT_MODE (DI, 8);
 162 INT_MODE (TI, 16);
 163
 164 /* No partial integer modes are defined by default.  */
 165
 166 /* Basic floating point modes.  SF and DF are the only modes provided
 167    by default.  The names QF, HF, XF, and TF are reserved for targets
 168    that need 1-word, 2-word, 80-bit, or 128-bit float types respectively.
 169
 170    These are the IEEE mappings.  They can be overridden with
 171    RESET_FLOAT_FORMAT or at runtime (in OVERRIDE_OPTIONS).  */
 172
 173 FLOAT_MODE (SF, 4, ieee_single_format);
 174 FLOAT_MODE (DF, 8, ieee_double_format);
 175
 176 /* Basic CC modes.
 177    FIXME define this only for targets that need it.  */
 178 CC_MODE (CC);
 179
 180 /* Allow the target to specify additional modes of various kinds.  */
 181 #if HAVE_EXTRA_MODES
 182 # include EXTRA_MODES_FILE
 183 #endif
 184
 185 /* Complex modes.  */
 186 COMPLEX_MODES (INT);
 187 COMPLEX_MODES (FLOAT);
 188
 189 /* The symbol Pmode stands for one of the above machine modes (usually SImode).
 190    The tm.h file specifies which one.  It is not a distinct mode.  */
 191
 192 /*
 193 Local variables:
 194 mode:c
 195 version-control: t
 196 End:
 197 */