gnu/dist/gcc4/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 #include "hard-reg-set.h"
  66
  67
  68 void
  69 default_external_libcall (rtx fun ATTRIBUTE_UNUSED)
  70 {
  71 #ifdef ASM_OUTPUT_EXTERNAL_LIBCALL
  72   ASM_OUTPUT_EXTERNAL_LIBCALL(asm_out_file, fun);
  73 #endif
  74 }
  75
  76 enum machine_mode
  77 default_cc_modes_compatible (enum machine_mode m1, enum machine_mode m2)
  78 {
  79   if (m1 == m2)
  80     return m1;
  81   return VOIDmode;
  82 }
  83
  84 bool
  85 default_return_in_memory (tree type,
  86                           tree fntype ATTRIBUTE_UNUSED)
  87 {
  88 #ifndef RETURN_IN_MEMORY
  89   return (TYPE_MODE (type) == BLKmode);
  90 #else
  91   return RETURN_IN_MEMORY (type);
  92 #endif
  93 }
  94
  95 rtx
  96 default_expand_builtin_saveregs (void)
  97 {
  98   error ("__builtin_saveregs not supported by this target");
  99   return const0_rtx;
 100 }
 101
 102 void
 103 default_setup_incoming_varargs (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 104                                 enum machine_mode mode ATTRIBUTE_UNUSED,
 105                                 tree type ATTRIBUTE_UNUSED,
 106                                 int *pretend_arg_size ATTRIBUTE_UNUSED,
 107                                 int second_time ATTRIBUTE_UNUSED)
 108 {
 109 }
 110
 111 /* The default implementation of TARGET_BUILTIN_SETJMP_FRAME_VALUE.  */
 112
 113 rtx
 114 default_builtin_setjmp_frame_value (void)
 115 {
 116   return virtual_stack_vars_rtx;
 117 }
 118
 119 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns false.  */
 120
 121 bool
 122 hook_bool_CUMULATIVE_ARGS_false (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 123 {
 124   return false;
 125 }
 126
 127 bool
 128 default_pretend_outgoing_varargs_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 129 {
 130   return (targetm.calls.setup_incoming_varargs
 131           != default_setup_incoming_varargs);
 132 }
 133
 134 enum machine_mode
 135 default_eh_return_filter_mode (void)
 136 {
 137   return word_mode;
 138 }
 139
 140 /* The default implementation of TARGET_SHIFT_TRUNCATION_MASK.  */
 141
 142 unsigned HOST_WIDE_INT
 143 default_shift_truncation_mask (enum machine_mode mode)
 144 {
 145   return SHIFT_COUNT_TRUNCATED ? GET_MODE_BITSIZE (mode) - 1 : 0;
 146 }
 147
 148 /* The default implementation of TARGET_MIN_DIVISIONS_FOR_RECIP_MUL.  */
 149
 150 unsigned int
 151 default_min_divisions_for_recip_mul (enum machine_mode mode ATTRIBUTE_UNUSED)
 152 {
 153   return have_insn_for (DIV, mode) ? 3 : 2;
 154 }
 155
 156 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns true.  */
 157
 158 bool
 159 hook_bool_CUMULATIVE_ARGS_true (CUMULATIVE_ARGS * a ATTRIBUTE_UNUSED)
 160 {
 161   return true;
 162 }
 163
 164
 165 /* The generic C++ ABI specifies this is a 64-bit value.  */
 166 tree
 167 default_cxx_guard_type (void)
 168 {
 169   return long_long_integer_type_node;
 170 }
 171
 172
 173 /* Returns the size of the cookie to use when allocating an array
 174    whose elements have the indicated TYPE.  Assumes that it is already
 175    known that a cookie is needed.  */
 176
 177 tree
 178 default_cxx_get_cookie_size (tree type)
 179 {
 180   tree cookie_size;
 181
 182   /* We need to allocate an additional max (sizeof (size_t), alignof
 183      (true_type)) bytes.  */
 184   tree sizetype_size;
 185   tree type_align;
 186
 187   sizetype_size = size_in_bytes (sizetype);
 188   type_align = size_int (TYPE_ALIGN_UNIT (type));
 189   if (INT_CST_LT_UNSIGNED (type_align, sizetype_size))
 190     cookie_size = sizetype_size;
 191   else
 192     cookie_size = type_align;
 193
 194   return cookie_size;
 195 }
 196
 197 /* Return true if a parameter must be passed by reference.  This version
 198    of the TARGET_PASS_BY_REFERENCE hook uses just MUST_PASS_IN_STACK.  */
 199
 200 bool
 201 hook_pass_by_reference_must_pass_in_stack (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED,
 202         enum machine_mode mode ATTRIBUTE_UNUSED, tree type ATTRIBUTE_UNUSED,
 203         bool named_arg ATTRIBUTE_UNUSED)
 204 {
 205   return targetm.calls.must_pass_in_stack (mode, type);
 206 }
 207
 208 /* Return true if a parameter follows callee copies conventions.  This
 209    version of the hook is true for all named arguments.  */
 210
 211 bool
 212 hook_callee_copies_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 213                           enum machine_mode mode ATTRIBUTE_UNUSED,
 214                           tree type ATTRIBUTE_UNUSED, bool named)
 215 {
 216   return named;
 217 }
 218
 219 /* Emit any directives required to unwind this instruction.  */
 220
 221 void
 222 default_unwind_emit (FILE * stream ATTRIBUTE_UNUSED,
 223                      rtx insn ATTRIBUTE_UNUSED)
 224 {
 225   /* Should never happen.  */
 226   gcc_unreachable ();
 227 }
 228
 229 /* True if MODE is valid for the target.  By "valid", we mean able to
 230    be manipulated in non-trivial ways.  In particular, this means all
 231    the arithmetic is supported.
 232
 233    By default we guess this means that any C type is supported.  If
 234    we can't map the mode back to a type that would be available in C,
 235    then reject it.  Special case, here, is the double-word arithmetic
 236    supported by optabs.c.  */
 237
 238 bool
 239 default_scalar_mode_supported_p (enum machine_mode mode)
 240 {
 241   int precision = GET_MODE_PRECISION (mode);
 242
 243   switch (GET_MODE_CLASS (mode))
 244     {
 245     case MODE_PARTIAL_INT:
 246     case MODE_INT:
 247       if (precision == CHAR_TYPE_SIZE)
 248         return true;
 249       if (precision == SHORT_TYPE_SIZE)
 250         return true;
 251       if (precision == INT_TYPE_SIZE)
 252         return true;
 253       if (precision == LONG_TYPE_SIZE)
 254         return true;
 255       if (precision == LONG_LONG_TYPE_SIZE)
 256         return true;
 257       if (precision == 2 * BITS_PER_WORD)
 258         return true;
 259       return false;
 260
 261     case MODE_FLOAT:
 262       if (precision == FLOAT_TYPE_SIZE)
 263         return true;
 264       if (precision == DOUBLE_TYPE_SIZE)
 265         return true;
 266       if (precision == LONG_DOUBLE_TYPE_SIZE)
 267         return true;
 268       return false;
 269
 270     default:
 271       gcc_unreachable ();
 272     }
 273 }
 274
 275 /* NULL if INSN insn is valid within a low-overhead loop, otherwise returns
 276    an error message.
 277
 278    This function checks whether a given INSN is valid within a low-overhead
 279    loop.  If INSN is invalid it returns the reason for that, otherwise it
 280    returns NULL. A called function may clobber any special registers required
 281    for low-overhead looping. Additionally, some targets (eg, PPC) use the count
 282    register for branch on table instructions. We reject the doloop pattern in
 283    these cases.  */
 284
 285 const char *
 286 default_invalid_within_doloop (rtx insn)
 287 {
 288   if (CALL_P (insn))
 289     return "Function call in loop.";
 290
 291   if (JUMP_P (insn)
 292       && (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
 293           || GET_CODE (PATTERN (insn)) == ADDR_VEC))
 294     return "Computed branch in the loop.";
 295
 296   return NULL;
 297 }
 298
 299 bool
 300 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false (
 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 false;
 306 }
 307
 308 bool
 309 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_true (
 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 true;
 315 }
 316
 317 int
 318 hook_int_CUMULATIVE_ARGS_mode_tree_bool_0 (
 319         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 320         enum machine_mode mode ATTRIBUTE_UNUSED,
 321         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 322 {
 323   return 0;
 324 }
 325
 326 const char *
 327 hook_invalid_arg_for_unprototyped_fn (
 328         tree typelist ATTRIBUTE_UNUSED,
 329         tree funcdecl ATTRIBUTE_UNUSED,
 330         tree val ATTRIBUTE_UNUSED)
 331 {
 332   return NULL;
 333 }
 334
 335 /* Initialize the stack protection decls.  */
 336
 337 /* Stack protection related decls living in libgcc.  */
 338 static GTY(()) tree stack_chk_guard_decl;
 339
 340 tree
 341 default_stack_protect_guard (void)
 342 {
 343   tree t = stack_chk_guard_decl;
 344
 345   if (t == NULL)
 346     {
 347       t = build_decl (VAR_DECL, get_identifier ("__stack_chk_guard"),
 348                       ptr_type_node);
 349       TREE_STATIC (t) = 1;
 350       TREE_PUBLIC (t) = 1;
 351       DECL_EXTERNAL (t) = 1;
 352       TREE_USED (t) = 1;
 353       TREE_THIS_VOLATILE (t) = 1;
 354       DECL_ARTIFICIAL (t) = 1;
 355       DECL_IGNORED_P (t) = 1;
 356
 357       stack_chk_guard_decl = t;
 358     }
 359
 360   return t;
 361 }
 362
 363 static GTY(()) tree stack_chk_fail_decl;
 364
 365 tree
 366 default_external_stack_protect_fail (void)
 367 {
 368   tree t = stack_chk_fail_decl;
 369
 370   if (t == NULL_TREE)
 371     {
 372       t = build_function_type_list (void_type_node, NULL_TREE);
 373       t = build_decl (FUNCTION_DECL, get_identifier ("__stack_chk_fail"), t);
 374       TREE_STATIC (t) = 1;
 375       TREE_PUBLIC (t) = 1;
 376       DECL_EXTERNAL (t) = 1;
 377       TREE_USED (t) = 1;
 378       TREE_THIS_VOLATILE (t) = 1;
 379       TREE_NOTHROW (t) = 1;
 380       DECL_ARTIFICIAL (t) = 1;
 381       DECL_IGNORED_P (t) = 1;
 382       DECL_VISIBILITY (t) = VISIBILITY_DEFAULT;
 383       DECL_VISIBILITY_SPECIFIED (t) = 1;
 384
 385       stack_chk_fail_decl = t;
 386     }
 387
 388   return build_function_call_expr (t, NULL_TREE);
 389 }
 390
 391 tree
 392 default_hidden_stack_protect_fail (void)
 393 {
 394 #ifndef HAVE_GAS_HIDDEN
 395   return default_external_stack_protect_fail ();
 396 #else
 397   tree t = stack_chk_fail_decl;
 398
 399   if (!flag_pic)
 400     return default_external_stack_protect_fail ();
 401
 402   if (t == NULL_TREE)
 403     {
 404       t = build_function_type_list (void_type_node, NULL_TREE);
 405       t = build_decl (FUNCTION_DECL,
 406                       get_identifier ("__stack_chk_fail_local"), t);
 407       TREE_STATIC (t) = 1;
 408       TREE_PUBLIC (t) = 1;
 409       DECL_EXTERNAL (t) = 1;
 410       TREE_USED (t) = 1;
 411       TREE_THIS_VOLATILE (t) = 1;
 412       TREE_NOTHROW (t) = 1;
 413       DECL_ARTIFICIAL (t) = 1;
 414       DECL_IGNORED_P (t) = 1;
 415       DECL_VISIBILITY_SPECIFIED (t) = 1;
 416 #if 1
 417       /*
 418        * This is a hack:
 419        * It appears that our gas does not generate @PLT for hidden
 420        * symbols. It could be that we need a newer version, or that
 421        * this local function is handled differently on linux.
 422        */
 423       DECL_VISIBILITY (t) = VISIBILITY_DEFAULT;
 424 #else
 425       DECL_VISIBILITY (t) = VISIBILITY_HIDDEN;
 426 #endif
 427
 428       stack_chk_fail_decl = t;
 429     }
 430
 431   return build_function_call_expr (t, NULL_TREE);
 432 #endif
 433 }
 434
 435 bool
 436 hook_bool_rtx_commutative_p (rtx x, int outer_code ATTRIBUTE_UNUSED)
 437 {
 438   return COMMUTATIVE_P (x);
 439 }
 440
 441 rtx
 442 default_function_value (tree ret_type ATTRIBUTE_UNUSED,
 443                         tree fn_decl_or_type,
 444                         bool outgoing ATTRIBUTE_UNUSED)
 445 {
 446   /* The old interface doesn't handle receiving the function type.  */
 447   if (fn_decl_or_type
 448       && !DECL_P (fn_decl_or_type))
 449     fn_decl_or_type = NULL;
 450
 451 #ifdef FUNCTION_OUTGOING_VALUE
 452   if (outgoing)
 453     return FUNCTION_OUTGOING_VALUE (ret_type, fn_decl_or_type);
 454 #endif
 455
 456 #ifdef FUNCTION_VALUE
 457   return FUNCTION_VALUE (ret_type, fn_decl_or_type);
 458 #else
 459   return NULL_RTX;
 460 #endif
 461 }
 462
 463 rtx
 464 default_internal_arg_pointer (void)
 465 {
 466   /* If the reg that the virtual arg pointer will be translated into is
 467      not a fixed reg or is the stack pointer, make a copy of the virtual
 468      arg pointer, and address parms via the copy.  The frame pointer is
 469      considered fixed even though it is not marked as such.  */
 470   if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM
 471        || ! (fixed_regs[ARG_POINTER_REGNUM]
 472              || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM)))
 473     return copy_to_reg (virtual_incoming_args_rtx);
 474   else
 475     return virtual_incoming_args_rtx;
 476 }
 477
 478 #include "gt-targhooks.h"