gcc/targhooks.c

   1 /* Default target hook functions.
   2    Copyright (C) 2003, 2004 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 2, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING.  If not, write to the Free
  18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  19 02111-1307, USA.  */
  20
  21 /* The migration of target macros to target hooks works as follows:
  22
  23    1. Create a target hook that uses the existing target macros to
  24       implement the same functionality.
  25
  26    2. Convert all the MI files to use the hook instead of the macro.
  27
  28    3. Repeat for a majority of the remaining target macros.  This will
  29       take some time.
  30
  31    4. Tell target maintainers to start migrating.
  32
  33    5. Eventually convert the backends to override the hook instead of
  34       defining the macros.  This will take some time too.
  35
  36    6. TBD when, poison the macros.  Unmigrated targets will break at
  37       this point.
  38
  39    Note that we expect steps 1-3 to be done by the people that
  40    understand what the MI does with each macro, and step 5 to be done
  41    by the target maintainers for their respective targets.
  42
  43    Note that steps 1 and 2 don't have to be done together, but no
  44    target can override the new hook until step 2 is complete for it.
  45
  46    Once the macros are poisoned, we will revert to the old migration
  47    rules - migrate the macro, callers, and targets all at once.  This
  48    comment can thus be removed at that point.  */
  49
  50 #include "config.h"
  51 #include "system.h"
  52 #include "coretypes.h"
  53 #include "tm.h"
  54 #include "machmode.h"
  55 #include "rtl.h"
  56 #include "tree.h"
  57 #include "expr.h"
  58 #include "output.h"
  59 #include "toplev.h"
  60 #include "function.h"
  61 #include "target.h"
  62 #include "tm_p.h"
  63 #include "target-def.h"
  64
  65
  66 void
  67 default_external_libcall (rtx fun ATTRIBUTE_UNUSED)
  68 {
  69 #ifdef ASM_OUTPUT_EXTERNAL_LIBCALL
  70   ASM_OUTPUT_EXTERNAL_LIBCALL(asm_out_file, fun);
  71 #endif
  72 }
  73
  74 enum machine_mode
  75 default_cc_modes_compatible (enum machine_mode m1, enum machine_mode m2)
  76 {
  77   if (m1 == m2)
  78     return m1;
  79   return VOIDmode;
  80 }
  81
  82 bool
  83 default_return_in_memory (tree type,
  84                           tree fntype ATTRIBUTE_UNUSED)
  85 {
  86 #ifndef RETURN_IN_MEMORY
  87   return (TYPE_MODE (type) == BLKmode);
  88 #else
  89   return RETURN_IN_MEMORY (type);
  90 #endif
  91 }
  92
  93 rtx
  94 default_expand_builtin_saveregs (void)
  95 {
  96   error ("__builtin_saveregs not supported by this target");
  97   return const0_rtx;
  98 }
  99
 100 void
 101 default_setup_incoming_varargs (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 102                                 enum machine_mode mode ATTRIBUTE_UNUSED,
 103                                 tree type ATTRIBUTE_UNUSED,
 104                                 int *pretend_arg_size ATTRIBUTE_UNUSED,
 105                                 int second_time ATTRIBUTE_UNUSED)
 106 {
 107 }
 108
 109 /* The default implementation of TARGET_BUILTIN_SETJMP_FRAME_VALUE.  */
 110
 111 rtx
 112 default_builtin_setjmp_frame_value (void)
 113 {
 114   return virtual_stack_vars_rtx;
 115 }
 116
 117 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns false.  */
 118
 119 bool
 120 hook_bool_CUMULATIVE_ARGS_false (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 121 {
 122   return false;
 123 }
 124
 125 bool
 126 default_pretend_outgoing_varargs_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 127 {
 128   return (targetm.calls.setup_incoming_varargs
 129           != default_setup_incoming_varargs);
 130 }
 131
 132 enum machine_mode
 133 default_eh_return_filter_mode (void)
 134 {
 135   return word_mode;
 136 }
 137
 138 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns true.  */
 139
 140 bool
 141 hook_bool_CUMULATIVE_ARGS_true (CUMULATIVE_ARGS * a ATTRIBUTE_UNUSED)
 142 {
 143   return true;
 144 }
 145
 146
 147 /* The generic C++ ABI specifies this is a 64-bit value.  */
 148 tree
 149 default_cxx_guard_type (void)
 150 {
 151   return long_long_integer_type_node;
 152 }
 153
 154
 155 /* Returns the size of the cookie to use when allocating an array
 156    whose elements have the indicated TYPE.  Assumes that it is already
 157    known that a cookie is needed.  */
 158
 159 tree
 160 default_cxx_get_cookie_size (tree type)
 161 {
 162   tree cookie_size;
 163
 164   /* We need to allocate an additional max (sizeof (size_t), alignof
 165      (true_type)) bytes.  */
 166   tree sizetype_size;
 167   tree type_align;
 168
 169   sizetype_size = size_in_bytes (sizetype);
 170   type_align = size_int (TYPE_ALIGN_UNIT (type));
 171   if (INT_CST_LT_UNSIGNED (type_align, sizetype_size))
 172     cookie_size = sizetype_size;
 173   else
 174     cookie_size = type_align;
 175
 176   return cookie_size;
 177 }
 178
 179 /* This version of the TARGET_PASS_BY_REFERENCE hook adds no conditions
 180    beyond those mandated by generic code.  */
 181
 182 bool
 183 hook_pass_by_reference_false (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED,
 184         enum machine_mode mode ATTRIBUTE_UNUSED, tree type ATTRIBUTE_UNUSED,
 185         bool named_arg ATTRIBUTE_UNUSED)
 186 {
 187   return false;
 188 }
 189
 190 /* Return true if a parameter must be passed by reference.  This version
 191    of the TARGET_PASS_BY_REFERENCE hook uses just MUST_PASS_IN_STACK.  */
 192
 193 bool
 194 hook_pass_by_reference_must_pass_in_stack (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED,
 195         enum machine_mode mode ATTRIBUTE_UNUSED, tree type ATTRIBUTE_UNUSED,
 196         bool named_arg ATTRIBUTE_UNUSED)
 197 {
 198   return targetm.calls.must_pass_in_stack (mode, type);
 199 }
 200
 201
 202 /* Emit any directives required to unwind this instruction.  */
 203
 204 void
 205 default_unwind_emit (FILE * stream ATTRIBUTE_UNUSED,
 206                      rtx insn ATTRIBUTE_UNUSED)
 207 {
 208   /* Should never happen.  */
 209   abort ();
 210 }
 211
 212 /* True if MODE is valid for the target.  By "valid", we mean able to
 213    be manipulated in non-trivial ways.  In particular, this means all
 214    the arithmetic is supported.
 215
 216    By default we guess this means that any C type is supported.  If
 217    we can't map the mode back to a type that would be available in C,
 218    then reject it.  Special case, here, is the double-word arithmetic
 219    supported by optabs.c.  */
 220
 221 bool
 222 default_scalar_mode_supported_p (enum machine_mode mode)
 223 {
 224   int precision = GET_MODE_PRECISION (mode);
 225
 226   switch (GET_MODE_CLASS (mode))
 227     {
 228     case MODE_PARTIAL_INT:
 229     case MODE_INT:
 230       if (precision == CHAR_TYPE_SIZE)
 231         return true;
 232       if (precision == SHORT_TYPE_SIZE)
 233         return true;
 234       if (precision == INT_TYPE_SIZE)
 235         return true;
 236       if (precision == LONG_TYPE_SIZE)
 237         return true;
 238       if (precision == LONG_LONG_TYPE_SIZE)
 239         return true;
 240       if (precision == 2 * BITS_PER_WORD)
 241         return true;
 242       return false;
 243
 244     case MODE_FLOAT:
 245       if (precision == FLOAT_TYPE_SIZE)
 246         return true;
 247       if (precision == DOUBLE_TYPE_SIZE)
 248         return true;
 249       if (precision == LONG_DOUBLE_TYPE_SIZE)
 250         return true;
 251       return false;
 252
 253     default:
 254       abort ();
 255     }
 256 }