gcc/targhooks.c

   1 /* Default target hook functions.
   2    Copyright (C) 2003, 2004, 2005 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, 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301, 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 #include "ggc.h"
  65
  66
  67 void
  68 default_external_libcall (rtx fun ATTRIBUTE_UNUSED)
  69 {
  70 #ifdef ASM_OUTPUT_EXTERNAL_LIBCALL
  71   ASM_OUTPUT_EXTERNAL_LIBCALL(asm_out_file, fun);
  72 #endif
  73 }
  74
  75 enum machine_mode
  76 default_cc_modes_compatible (enum machine_mode m1, enum machine_mode m2)
  77 {
  78   if (m1 == m2)
  79     return m1;
  80   return VOIDmode;
  81 }
  82
  83 bool
  84 default_return_in_memory (tree type,
  85                           tree fntype ATTRIBUTE_UNUSED)
  86 {
  87 #ifndef RETURN_IN_MEMORY
  88   return (TYPE_MODE (type) == BLKmode);
  89 #else
  90   return RETURN_IN_MEMORY (type);
  91 #endif
  92 }
  93
  94 rtx
  95 default_expand_builtin_saveregs (void)
  96 {
  97   error ("__builtin_saveregs not supported by this target");
  98   return const0_rtx;
  99 }
 100
 101 void
 102 default_setup_incoming_varargs (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 103                                 enum machine_mode mode ATTRIBUTE_UNUSED,
 104                                 tree type ATTRIBUTE_UNUSED,
 105                                 int *pretend_arg_size ATTRIBUTE_UNUSED,
 106                                 int second_time ATTRIBUTE_UNUSED)
 107 {
 108 }
 109
 110 /* The default implementation of TARGET_BUILTIN_SETJMP_FRAME_VALUE.  */
 111
 112 rtx
 113 default_builtin_setjmp_frame_value (void)
 114 {
 115   return virtual_stack_vars_rtx;
 116 }
 117
 118 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns false.  */
 119
 120 bool
 121 hook_bool_CUMULATIVE_ARGS_false (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 122 {
 123   return false;
 124 }
 125
 126 bool
 127 default_pretend_outgoing_varargs_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 128 {
 129   return (targetm.calls.setup_incoming_varargs
 130           != default_setup_incoming_varargs);
 131 }
 132
 133 enum machine_mode
 134 default_eh_return_filter_mode (void)
 135 {
 136   return word_mode;
 137 }
 138
 139 /* The default implementation of TARGET_SHIFT_TRUNCATION_MASK.  */
 140
 141 unsigned HOST_WIDE_INT
 142 default_shift_truncation_mask (enum machine_mode mode)
 143 {
 144   return SHIFT_COUNT_TRUNCATED ? GET_MODE_BITSIZE (mode) - 1 : 0;
 145 }
 146
 147 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns true.  */
 148
 149 bool
 150 hook_bool_CUMULATIVE_ARGS_true (CUMULATIVE_ARGS * a ATTRIBUTE_UNUSED)
 151 {
 152   return true;
 153 }
 154
 155
 156 /* The generic C++ ABI specifies this is a 64-bit value.  */
 157 tree
 158 default_cxx_guard_type (void)
 159 {
 160   return long_long_integer_type_node;
 161 }
 162
 163
 164 /* Returns the size of the cookie to use when allocating an array
 165    whose elements have the indicated TYPE.  Assumes that it is already
 166    known that a cookie is needed.  */
 167
 168 tree
 169 default_cxx_get_cookie_size (tree type)
 170 {
 171   tree cookie_size;
 172
 173   /* We need to allocate an additional max (sizeof (size_t), alignof
 174      (true_type)) bytes.  */
 175   tree sizetype_size;
 176   tree type_align;
 177
 178   sizetype_size = size_in_bytes (sizetype);
 179   type_align = size_int (TYPE_ALIGN_UNIT (type));
 180   if (INT_CST_LT_UNSIGNED (type_align, sizetype_size))
 181     cookie_size = sizetype_size;
 182   else
 183     cookie_size = type_align;
 184
 185   return cookie_size;
 186 }
 187
 188 /* Return true if a parameter must be passed by reference.  This version
 189    of the TARGET_PASS_BY_REFERENCE hook uses just MUST_PASS_IN_STACK.  */
 190
 191 bool
 192 hook_pass_by_reference_must_pass_in_stack (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED,
 193         enum machine_mode mode ATTRIBUTE_UNUSED, tree type ATTRIBUTE_UNUSED,
 194         bool named_arg ATTRIBUTE_UNUSED)
 195 {
 196   return targetm.calls.must_pass_in_stack (mode, type);
 197 }
 198
 199 /* Return true if a parameter follows callee copies conventions.  This
 200    version of the hook is true for all named arguments.  */
 201
 202 bool
 203 hook_callee_copies_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 204                           enum machine_mode mode ATTRIBUTE_UNUSED,
 205                           tree type ATTRIBUTE_UNUSED, bool named)
 206 {
 207   return named;
 208 }
 209
 210 /* Emit any directives required to unwind this instruction.  */
 211
 212 void
 213 default_unwind_emit (FILE * stream ATTRIBUTE_UNUSED,
 214                      rtx insn ATTRIBUTE_UNUSED)
 215 {
 216   /* Should never happen.  */
 217   gcc_unreachable ();
 218 }
 219
 220 /* True if MODE is valid for the target.  By "valid", we mean able to
 221    be manipulated in non-trivial ways.  In particular, this means all
 222    the arithmetic is supported.
 223
 224    By default we guess this means that any C type is supported.  If
 225    we can't map the mode back to a type that would be available in C,
 226    then reject it.  Special case, here, is the double-word arithmetic
 227    supported by optabs.c.  */
 228
 229 bool
 230 default_scalar_mode_supported_p (enum machine_mode mode)
 231 {
 232   int precision = GET_MODE_PRECISION (mode);
 233
 234   switch (GET_MODE_CLASS (mode))
 235     {
 236     case MODE_PARTIAL_INT:
 237     case MODE_INT:
 238       if (precision == CHAR_TYPE_SIZE)
 239         return true;
 240       if (precision == SHORT_TYPE_SIZE)
 241         return true;
 242       if (precision == INT_TYPE_SIZE)
 243         return true;
 244       if (precision == LONG_TYPE_SIZE)
 245         return true;
 246       if (precision == LONG_LONG_TYPE_SIZE)
 247         return true;
 248       if (precision == 2 * BITS_PER_WORD)
 249         return true;
 250       return false;
 251
 252     case MODE_FLOAT:
 253       if (precision == FLOAT_TYPE_SIZE)
 254         return true;
 255       if (precision == DOUBLE_TYPE_SIZE)
 256         return true;
 257       if (precision == LONG_DOUBLE_TYPE_SIZE)
 258         return true;
 259       return false;
 260
 261     default:
 262       gcc_unreachable ();
 263     }
 264 }
 265
 266 /* NULL if INSN insn is valid within a low-overhead loop, otherwise returns
 267    an error message.
 268
 269    This function checks whether a given INSN is valid within a low-overhead
 270    loop.  If INSN is invalid it returns the reason for that, otherwise it
 271    returns NULL. A called function may clobber any special registers required
 272    for low-overhead looping. Additionally, some targets (eg, PPC) use the count
 273    register for branch on table instructions. We reject the doloop pattern in
 274    these cases.  */
 275
 276 const char *
 277 default_invalid_within_doloop (rtx insn)
 278 {
 279   if (CALL_P (insn))
 280     return "Function call in loop.";
 281
 282   if (JUMP_P (insn)
 283       && (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
 284           || GET_CODE (PATTERN (insn)) == ADDR_VEC))
 285     return "Computed branch in the loop.";
 286
 287   return NULL;
 288 }
 289
 290 bool
 291 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false (
 292         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 293         enum machine_mode mode ATTRIBUTE_UNUSED,
 294         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 295 {
 296   return false;
 297 }
 298
 299 bool
 300 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_true (
 301         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 302         enum machine_mode mode ATTRIBUTE_UNUSED,
 303         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 304 {
 305   return true;
 306 }
 307
 308 int
 309 hook_int_CUMULATIVE_ARGS_mode_tree_bool_0 (
 310         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 311         enum machine_mode mode ATTRIBUTE_UNUSED,
 312         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 313 {
 314   return 0;
 315 }
 316
 317 const char *
 318 hook_invalid_arg_for_unprototyped_fn (
 319         tree typelist ATTRIBUTE_UNUSED,
 320         tree funcdecl ATTRIBUTE_UNUSED,
 321         tree val ATTRIBUTE_UNUSED)
 322 {
 323   return NULL;
 324 }
 325
 326 /* Initialize the stack protection decls.  */
 327
 328 /* Stack protection related decls living in libgcc.  */
 329 static GTY(()) tree stack_chk_guard_decl;
 330
 331 tree
 332 default_stack_protect_guard (void)
 333 {
 334   tree t = stack_chk_guard_decl;
 335
 336   if (t == NULL)
 337     {
 338       t = build_decl (VAR_DECL, get_identifier ("__stack_chk_guard"),
 339                       ptr_type_node);
 340       TREE_STATIC (t) = 1;
 341       TREE_PUBLIC (t) = 1;
 342       DECL_EXTERNAL (t) = 1;
 343       TREE_USED (t) = 1;
 344       TREE_THIS_VOLATILE (t) = 1;
 345       DECL_ARTIFICIAL (t) = 1;
 346       DECL_IGNORED_P (t) = 1;
 347
 348       stack_chk_guard_decl = t;
 349     }
 350
 351   return t;
 352 }
 353
 354 static GTY(()) tree stack_chk_fail_decl;
 355
 356 tree
 357 default_external_stack_protect_fail (void)
 358 {
 359   tree t = stack_chk_fail_decl;
 360
 361   if (t == NULL_TREE)
 362     {
 363       t = build_function_type_list (void_type_node, NULL_TREE);
 364       t = build_decl (FUNCTION_DECL, get_identifier ("__stack_chk_fail"), t);
 365       TREE_STATIC (t) = 1;
 366       TREE_PUBLIC (t) = 1;
 367       DECL_EXTERNAL (t) = 1;
 368       TREE_USED (t) = 1;
 369       TREE_THIS_VOLATILE (t) = 1;
 370       TREE_NOTHROW (t) = 1;
 371       DECL_ARTIFICIAL (t) = 1;
 372       DECL_IGNORED_P (t) = 1;
 373
 374       stack_chk_fail_decl = t;
 375     }
 376
 377   return build_function_call_expr (t, NULL_TREE);
 378 }
 379
 380 tree
 381 default_hidden_stack_protect_fail (void)
 382 {
 383 #ifndef HAVE_GAS_HIDDEN
 384   return default_external_stack_protect_fail ();
 385 #else
 386   tree t = stack_chk_fail_decl;
 387
 388   if (!flag_pic)
 389     return default_external_stack_protect_fail ();
 390
 391   if (t == NULL_TREE)
 392     {
 393       t = build_function_type_list (void_type_node, NULL_TREE);
 394       t = build_decl (FUNCTION_DECL,
 395                       get_identifier ("__stack_chk_fail_local"), t);
 396       TREE_STATIC (t) = 1;
 397       TREE_PUBLIC (t) = 1;
 398       DECL_EXTERNAL (t) = 1;
 399       TREE_USED (t) = 1;
 400       TREE_THIS_VOLATILE (t) = 1;
 401       TREE_NOTHROW (t) = 1;
 402       DECL_ARTIFICIAL (t) = 1;
 403       DECL_IGNORED_P (t) = 1;
 404       DECL_VISIBILITY_SPECIFIED (t) = 1;
 405       DECL_VISIBILITY (t) = VISIBILITY_HIDDEN;
 406
 407       stack_chk_fail_decl = t;
 408     }
 409
 410   return build_function_call_expr (t, NULL_TREE);
 411 #endif
 412 }
 413
 414 bool
 415 hook_bool_rtx_commutative_p (rtx x, int outer_code ATTRIBUTE_UNUSED)
 416 {
 417   return COMMUTATIVE_P (x);
 418 }
 419
 420 rtx
 421 default_function_value (tree ret_type ATTRIBUTE_UNUSED,
 422                         tree fn_decl_or_type,
 423                         bool outgoing ATTRIBUTE_UNUSED)
 424 {
 425   /* The old interface doesn't handle receiving the function type.  */
 426   if (fn_decl_or_type
 427       && !DECL_P (fn_decl_or_type))
 428     fn_decl_or_type = NULL;
 429
 430 #ifdef FUNCTION_OUTGOING_VALUE
 431   if (outgoing)
 432     return FUNCTION_OUTGOING_VALUE (ret_type, fn_decl_or_type);
 433 #endif
 434
 435 #ifdef FUNCTION_VALUE
 436   return FUNCTION_VALUE (ret_type, fn_decl_or_type);
 437 #else
 438   return NULL_RTX;
 439 #endif
 440 }
 441
 442 #include "gt-targhooks.h"