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 void
  66 default_external_libcall (rtx fun ATTRIBUTE_UNUSED)
  67 {
  68 #ifdef ASM_OUTPUT_EXTERNAL_LIBCALL
  69   ASM_OUTPUT_EXTERNAL_LIBCALL(asm_out_file, fun);
  70 #endif
  71 }
  72
  73 enum machine_mode
  74 default_cc_modes_compatible (enum machine_mode m1, enum machine_mode m2)
  75 {
  76   if (m1 == m2)
  77     return m1;
  78   return VOIDmode;
  79 }
  80
  81 bool
  82 default_return_in_memory (tree type,
  83                           tree fntype ATTRIBUTE_UNUSED)
  84 {
  85 #ifndef RETURN_IN_MEMORY
  86   return (TYPE_MODE (type) == BLKmode);
  87 #else
  88   return RETURN_IN_MEMORY (type);
  89 #endif
  90 }
  91
  92 rtx
  93 default_expand_builtin_saveregs (void)
  94 {
  95   error ("__builtin_saveregs not supported by this target");
  96   return const0_rtx;
  97 }
  98
  99 void
 100 default_setup_incoming_varargs (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 101                                 enum machine_mode mode ATTRIBUTE_UNUSED,
 102                                 tree type ATTRIBUTE_UNUSED,
 103                                 int *pretend_arg_size ATTRIBUTE_UNUSED,
 104                                 int second_time ATTRIBUTE_UNUSED)
 105 {
 106 }
 107
 108 /* The default implementation of TARGET_BUILTIN_SETJMP_FRAME_VALUE.  */
 109
 110 rtx
 111 default_builtin_setjmp_frame_value (void)
 112 {
 113   return virtual_stack_vars_rtx;
 114 }
 115
 116 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns false.  */
 117
 118 bool
 119 hook_bool_CUMULATIVE_ARGS_false (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 120 {
 121   return false;
 122 }
 123
 124 bool
 125 default_pretend_outgoing_varargs_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 126 {
 127   return (targetm.calls.setup_incoming_varargs
 128           != default_setup_incoming_varargs);
 129 }
 130
 131 enum machine_mode
 132 default_eh_return_filter_mode (void)
 133 {
 134   return word_mode;
 135 }
 136
 137 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns true.  */
 138
 139 bool
 140 hook_bool_CUMULATIVE_ARGS_true (CUMULATIVE_ARGS * a ATTRIBUTE_UNUSED)
 141 {
 142   return true;
 143 }
 144
 145
 146 /* The generic C++ ABI specifies this is a 64-bit value.  */
 147 tree
 148 default_cxx_guard_type (void)
 149 {
 150   return long_long_integer_type_node;
 151 }
 152
 153
 154 /* Returns the size of the cookie to use when allocating an array
 155    whose elements have the indicated TYPE.  Assumes that it is already
 156    known that a cookie is needed.  */
 157
 158 tree
 159 default_cxx_get_cookie_size (tree type)
 160 {
 161   tree cookie_size;
 162
 163   /* We need to allocate an additional max (sizeof (size_t), alignof
 164      (true_type)) bytes.  */
 165   tree sizetype_size;
 166   tree type_align;
 167
 168   sizetype_size = size_in_bytes (sizetype);
 169   type_align = size_int (TYPE_ALIGN_UNIT (type));
 170   if (INT_CST_LT_UNSIGNED (type_align, sizetype_size))
 171     cookie_size = sizetype_size;
 172   else
 173     cookie_size = type_align;
 174
 175   return cookie_size;
 176 }
 177
 178 /* This version of the TARGET_PASS_BY_REFERENCE hook adds no conditions
 179    beyond those mandated by generic code.  */
 180
 181 bool
 182 hook_pass_by_reference_false (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED,
 183         enum machine_mode mode ATTRIBUTE_UNUSED, tree type ATTRIBUTE_UNUSED,
 184         bool named_arg ATTRIBUTE_UNUSED)
 185 {
 186   return false;
 187 }
 188
 189 /* Return true if a parameter must be passed by reference.  This version
 190    of the TARGET_PASS_BY_REFERENCE hook uses just MUST_PASS_IN_STACK.  */
 191
 192 bool
 193 hook_pass_by_reference_must_pass_in_stack (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED,
 194         enum machine_mode mode ATTRIBUTE_UNUSED, tree type ATTRIBUTE_UNUSED,
 195         bool named_arg ATTRIBUTE_UNUSED)
 196 {
 197   return targetm.calls.must_pass_in_stack (mode, type);
 198 }
 199
 200
 201 /* Emit any directives required to unwind this instruction.  */
 202
 203 void
 204 default_unwind_emit (FILE * stream ATTRIBUTE_UNUSED,
 205                      rtx insn ATTRIBUTE_UNUSED)
 206 {
 207   /* Should never happen.  */
 208   abort ();
 209 }