1/* Default target hook functions. 2 Copyright (C) 2003, 2004, 2005, 2007 Free Software Foundation, Inc. 3 4This file is part of GCC. 5 6GCC is free software; you can redistribute it and/or modify it under 7the terms of the GNU General Public License as published by the Free 8Software Foundation; either version 2, or (at your option) any later 9version. 10 11GCC is distributed in the hope that it will be useful, but WITHOUT ANY 12WARRANTY; without even the implied warranty of MERCHANTABILITY or 13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14for more details. 15 16You should have received a copy of the GNU General Public License 17along with GCC; see the file COPYING. If not, write to the Free 18Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 1902110-1301, 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#include "reload.h" 67#include "optabs.h" 68#include "recog.h" 69 70 71void 72default_external_libcall (rtx fun ATTRIBUTE_UNUSED) 73{ 74#ifdef ASM_OUTPUT_EXTERNAL_LIBCALL 75 ASM_OUTPUT_EXTERNAL_LIBCALL(asm_out_file, fun); 76#endif 77} 78 79enum machine_mode 80default_cc_modes_compatible (enum machine_mode m1, enum machine_mode m2) 81{ 82 if (m1 == m2) 83 return m1; 84 return VOIDmode; 85} 86 87bool 88default_return_in_memory (tree type, 89 tree fntype ATTRIBUTE_UNUSED) 90{ 91#ifndef RETURN_IN_MEMORY 92 return (TYPE_MODE (type) == BLKmode); 93#else 94 return RETURN_IN_MEMORY (type); 95#endif 96} 97 98rtx 99default_expand_builtin_saveregs (void) 100{ 101 error ("__builtin_saveregs not supported by this target"); 102 return const0_rtx; 103} 104 105void 106default_setup_incoming_varargs (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED, 107 enum machine_mode mode ATTRIBUTE_UNUSED, 108 tree type ATTRIBUTE_UNUSED, 109 int *pretend_arg_size ATTRIBUTE_UNUSED, 110 int second_time ATTRIBUTE_UNUSED) 111{ 112} 113 114/* The default implementation of TARGET_BUILTIN_SETJMP_FRAME_VALUE. */ 115 116rtx 117default_builtin_setjmp_frame_value (void) 118{ 119 return virtual_stack_vars_rtx; 120} 121 122/* Generic hook that takes a CUMULATIVE_ARGS pointer and returns false. */ 123 124bool 125hook_bool_CUMULATIVE_ARGS_false (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED) 126{ 127 return false; 128} 129 130bool 131default_pretend_outgoing_varargs_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED) 132{ 133 return (targetm.calls.setup_incoming_varargs 134 != default_setup_incoming_varargs); 135} 136 137enum machine_mode 138default_eh_return_filter_mode (void) 139{ 140 return word_mode; 141} 142 143/* The default implementation of TARGET_SHIFT_TRUNCATION_MASK. */ 144 145unsigned HOST_WIDE_INT 146default_shift_truncation_mask (enum machine_mode mode) 147{ 148 return SHIFT_COUNT_TRUNCATED ? GET_MODE_BITSIZE (mode) - 1 : 0; 149} 150 151/* The default implementation of TARGET_MIN_DIVISIONS_FOR_RECIP_MUL. */ 152 153unsigned int 154default_min_divisions_for_recip_mul (enum machine_mode mode ATTRIBUTE_UNUSED) 155{ 156 return have_insn_for (DIV, mode) ? 3 : 2; 157} 158 159/* The default implementation of TARGET_MODE_REP_EXTENDED. */ 160 161int 162default_mode_rep_extended (enum machine_mode mode ATTRIBUTE_UNUSED, 163 enum machine_mode mode_rep ATTRIBUTE_UNUSED) 164{ 165 return UNKNOWN; 166} 167 168/* Generic hook that takes a CUMULATIVE_ARGS pointer and returns true. */ 169 170bool 171hook_bool_CUMULATIVE_ARGS_true (CUMULATIVE_ARGS * a ATTRIBUTE_UNUSED) 172{ 173 return true; 174} 175 176 177/* The generic C++ ABI specifies this is a 64-bit value. */ 178tree 179default_cxx_guard_type (void) 180{ 181 return long_long_integer_type_node; 182} 183 184 185/* Returns the size of the cookie to use when allocating an array 186 whose elements have the indicated TYPE. Assumes that it is already 187 known that a cookie is needed. */ 188 189tree 190default_cxx_get_cookie_size (tree type) 191{ 192 tree cookie_size; 193 194 /* We need to allocate an additional max (sizeof (size_t), alignof 195 (true_type)) bytes. */ 196 tree sizetype_size; 197 tree type_align; 198 199 sizetype_size = size_in_bytes (sizetype); 200 type_align = size_int (TYPE_ALIGN_UNIT (type)); 201 if (INT_CST_LT_UNSIGNED (type_align, sizetype_size)) 202 cookie_size = sizetype_size; 203 else 204 cookie_size = type_align; 205 206 return cookie_size; 207} 208 209/* Return true if a parameter must be passed by reference. This version 210 of the TARGET_PASS_BY_REFERENCE hook uses just MUST_PASS_IN_STACK. */ 211 212bool 213hook_pass_by_reference_must_pass_in_stack (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED, 214 enum machine_mode mode ATTRIBUTE_UNUSED, tree type ATTRIBUTE_UNUSED, 215 bool named_arg ATTRIBUTE_UNUSED) 216{ 217 return targetm.calls.must_pass_in_stack (mode, type); 218} 219 220/* Return true if a parameter follows callee copies conventions. This 221 version of the hook is true for all named arguments. */ 222 223bool 224hook_callee_copies_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED, 225 enum machine_mode mode ATTRIBUTE_UNUSED, 226 tree type ATTRIBUTE_UNUSED, bool named) 227{ 228 return named; 229} 230 231/* Emit any directives required to unwind this instruction. */ 232 233void 234default_unwind_emit (FILE * stream ATTRIBUTE_UNUSED, 235 rtx insn ATTRIBUTE_UNUSED) 236{ 237 /* Should never happen. */ 238 gcc_unreachable (); 239} 240 241/* True if MODE is valid for the target. By "valid", we mean able to 242 be manipulated in non-trivial ways. In particular, this means all 243 the arithmetic is supported. 244 245 By default we guess this means that any C type is supported. If 246 we can't map the mode back to a type that would be available in C, 247 then reject it. Special case, here, is the double-word arithmetic 248 supported by optabs.c. */ 249 250bool 251default_scalar_mode_supported_p (enum machine_mode mode) 252{ 253 int precision = GET_MODE_PRECISION (mode); 254 255 switch (GET_MODE_CLASS (mode)) 256 { 257 case MODE_PARTIAL_INT: 258 case MODE_INT: 259 if (precision == CHAR_TYPE_SIZE) 260 return true; 261 if (precision == SHORT_TYPE_SIZE) 262 return true; 263 if (precision == INT_TYPE_SIZE) 264 return true; 265 if (precision == LONG_TYPE_SIZE) 266 return true; 267 if (precision == LONG_LONG_TYPE_SIZE) 268 return true; 269 if (precision == 2 * BITS_PER_WORD) 270 return true; 271 return false; 272 273 case MODE_FLOAT: 274 if (precision == FLOAT_TYPE_SIZE) 275 return true; 276 if (precision == DOUBLE_TYPE_SIZE) 277 return true; 278 if (precision == LONG_DOUBLE_TYPE_SIZE) 279 return true; 280 return false; 281 282 case MODE_DECIMAL_FLOAT: 283 return false; 284 285 default: 286 gcc_unreachable (); 287 } 288} 289 290/* True if the target supports decimal floating point. */ 291 292bool 293default_decimal_float_supported_p (void) 294{ 295 return ENABLE_DECIMAL_FLOAT; 296} 297 298/* NULL if INSN insn is valid within a low-overhead loop, otherwise returns 299 an error message. 300 301 This function checks whether a given INSN is valid within a low-overhead 302 loop. If INSN is invalid it returns the reason for that, otherwise it 303 returns NULL. A called function may clobber any special registers required 304 for low-overhead looping. Additionally, some targets (eg, PPC) use the count 305 register for branch on table instructions. We reject the doloop pattern in 306 these cases. */ 307 308const char * 309default_invalid_within_doloop (rtx insn) 310{ 311 if (CALL_P (insn)) 312 return "Function call in loop."; 313 314 if (JUMP_P (insn) 315 && (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC 316 || GET_CODE (PATTERN (insn)) == ADDR_VEC)) 317 return "Computed branch in the loop."; 318 319 return NULL; 320} 321 322bool 323hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false ( 324 CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED, 325 enum machine_mode mode ATTRIBUTE_UNUSED, 326 tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED) 327{ 328 return false; 329} 330 331bool 332hook_bool_CUMULATIVE_ARGS_mode_tree_bool_true ( 333 CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED, 334 enum machine_mode mode ATTRIBUTE_UNUSED, 335 tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED) 336{ 337 return true; 338} 339 340int 341hook_int_CUMULATIVE_ARGS_mode_tree_bool_0 ( 342 CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED, 343 enum machine_mode mode ATTRIBUTE_UNUSED, 344 tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED) 345{ 346 return 0; 347} 348 349void 350hook_void_bitmap (bitmap regs ATTRIBUTE_UNUSED) 351{ 352} 353 354const char * 355hook_invalid_arg_for_unprototyped_fn ( 356 tree typelist ATTRIBUTE_UNUSED, 357 tree funcdecl ATTRIBUTE_UNUSED, 358 tree val ATTRIBUTE_UNUSED) 359{ 360 return NULL; 361} 362 363/* Initialize the stack protection decls. */ 364 365/* Stack protection related decls living in libgcc. */ 366static GTY(()) tree stack_chk_guard_decl; 367 368tree 369default_stack_protect_guard (void) 370{ 371 tree t = stack_chk_guard_decl; 372 373 if (t == NULL) 374 { 375 t = build_decl (VAR_DECL, get_identifier ("__stack_chk_guard"), 376 ptr_type_node); 377 TREE_STATIC (t) = 1; 378 TREE_PUBLIC (t) = 1; 379 DECL_EXTERNAL (t) = 1; 380 TREE_USED (t) = 1; 381 TREE_THIS_VOLATILE (t) = 1; 382 DECL_ARTIFICIAL (t) = 1; 383 DECL_IGNORED_P (t) = 1; 384 385 stack_chk_guard_decl = t; 386 } 387 388 return t; 389} 390 391static GTY(()) tree stack_chk_fail_decl; 392 393tree 394default_external_stack_protect_fail (void) 395{ 396 tree t = stack_chk_fail_decl; 397 398 if (t == NULL_TREE) 399 { 400 t = build_function_type_list (void_type_node, NULL_TREE); 401 t = build_decl (FUNCTION_DECL, get_identifier ("__stack_chk_fail"), t); 402 TREE_STATIC (t) = 1; 403 TREE_PUBLIC (t) = 1; 404 DECL_EXTERNAL (t) = 1; 405 TREE_USED (t) = 1; 406 TREE_THIS_VOLATILE (t) = 1; 407 TREE_NOTHROW (t) = 1; 408 DECL_ARTIFICIAL (t) = 1; 409 DECL_IGNORED_P (t) = 1; 410 DECL_VISIBILITY (t) = VISIBILITY_DEFAULT; 411 DECL_VISIBILITY_SPECIFIED (t) = 1; 412 413 stack_chk_fail_decl = t; 414 } 415 416 return build_function_call_expr (t, NULL_TREE); 417} 418 419tree 420default_hidden_stack_protect_fail (void) 421{ 422#ifndef HAVE_GAS_HIDDEN 423 return default_external_stack_protect_fail (); 424#else 425 tree t = stack_chk_fail_decl; 426 427 if (!flag_pic) 428 return default_external_stack_protect_fail (); 429 430 if (t == NULL_TREE) 431 { 432 t = build_function_type_list (void_type_node, NULL_TREE); 433 t = build_decl (FUNCTION_DECL, 434 get_identifier ("__stack_chk_fail_local"), t); 435 TREE_STATIC (t) = 1; 436 TREE_PUBLIC (t) = 1; 437 DECL_EXTERNAL (t) = 1; 438 TREE_USED (t) = 1; 439 TREE_THIS_VOLATILE (t) = 1; 440 TREE_NOTHROW (t) = 1; 441 DECL_ARTIFICIAL (t) = 1; 442 DECL_IGNORED_P (t) = 1; 443 DECL_VISIBILITY_SPECIFIED (t) = 1; 444 DECL_VISIBILITY (t) = VISIBILITY_HIDDEN; 445 446 stack_chk_fail_decl = t; 447 } 448 449 return build_function_call_expr (t, NULL_TREE); 450#endif 451} 452 453bool 454hook_bool_rtx_commutative_p (rtx x, int outer_code ATTRIBUTE_UNUSED) 455{ 456 return COMMUTATIVE_P (x); 457} 458 459rtx 460default_function_value (tree ret_type ATTRIBUTE_UNUSED, 461 tree fn_decl_or_type, 462 bool outgoing ATTRIBUTE_UNUSED) 463{ 464 /* The old interface doesn't handle receiving the function type. */ 465 if (fn_decl_or_type 466 && !DECL_P (fn_decl_or_type)) 467 fn_decl_or_type = NULL; 468 469#ifdef FUNCTION_OUTGOING_VALUE 470 if (outgoing) 471 return FUNCTION_OUTGOING_VALUE (ret_type, fn_decl_or_type); 472#endif 473 474#ifdef FUNCTION_VALUE 475 return FUNCTION_VALUE (ret_type, fn_decl_or_type); 476#else 477 return NULL_RTX; 478#endif 479} 480 481rtx 482default_internal_arg_pointer (void) 483{ 484 /* If the reg that the virtual arg pointer will be translated into is 485 not a fixed reg or is the stack pointer, make a copy of the virtual 486 arg pointer, and address parms via the copy. The frame pointer is 487 considered fixed even though it is not marked as such. */ 488 if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM 489 || ! (fixed_regs[ARG_POINTER_REGNUM] 490 || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM))) 491 return copy_to_reg (virtual_incoming_args_rtx); 492 else 493 return virtual_incoming_args_rtx; 494} 495 496enum reg_class 497default_secondary_reload (bool in_p ATTRIBUTE_UNUSED, rtx x ATTRIBUTE_UNUSED, 498 enum reg_class reload_class ATTRIBUTE_UNUSED, 499 enum machine_mode reload_mode ATTRIBUTE_UNUSED, 500 secondary_reload_info *sri) 501{ 502 enum reg_class class = NO_REGS; 503 504 if (sri->prev_sri && sri->prev_sri->t_icode != CODE_FOR_nothing) 505 { 506 sri->icode = sri->prev_sri->t_icode; 507 return NO_REGS; 508 } 509#ifdef SECONDARY_INPUT_RELOAD_CLASS 510 if (in_p) 511 class = SECONDARY_INPUT_RELOAD_CLASS (reload_class, reload_mode, x); 512#endif 513#ifdef SECONDARY_OUTPUT_RELOAD_CLASS 514 if (! in_p) 515 class = SECONDARY_OUTPUT_RELOAD_CLASS (reload_class, reload_mode, x); 516#endif 517 if (class != NO_REGS) 518 { 519 enum insn_code icode = (in_p ? reload_in_optab[(int) reload_mode] 520 : reload_out_optab[(int) reload_mode]); 521 522 if (icode != CODE_FOR_nothing 523 && insn_data[(int) icode].operand[in_p].predicate 524 && ! insn_data[(int) icode].operand[in_p].predicate (x, reload_mode)) 525 icode = CODE_FOR_nothing; 526 else if (icode != CODE_FOR_nothing) 527 { 528 const char *insn_constraint, *scratch_constraint; 529 char insn_letter, scratch_letter; 530 enum reg_class insn_class, scratch_class; 531 532 gcc_assert (insn_data[(int) icode].n_operands == 3); 533 insn_constraint = insn_data[(int) icode].operand[!in_p].constraint; 534 if (!*insn_constraint) 535 insn_class = ALL_REGS; 536 else 537 { 538 if (in_p) 539 { 540 gcc_assert (*insn_constraint == '='); 541 insn_constraint++; 542 } 543 insn_letter = *insn_constraint; 544 insn_class 545 = (insn_letter == 'r' ? GENERAL_REGS 546 : REG_CLASS_FROM_CONSTRAINT ((unsigned char) insn_letter, 547 insn_constraint)); 548 gcc_assert (insn_class != NO_REGS); 549 } 550 551 scratch_constraint = insn_data[(int) icode].operand[2].constraint; 552 /* The scratch register's constraint must start with "=&", 553 except for an input reload, where only "=" is necessary, 554 and where it might be beneficial to re-use registers from 555 the input. */ 556 gcc_assert (scratch_constraint[0] == '=' 557 && (in_p || scratch_constraint[1] == '&')); 558 scratch_constraint++; 559 if (*scratch_constraint == '&') 560 scratch_constraint++; 561 scratch_letter = *scratch_constraint; 562 scratch_class 563 = (scratch_letter == 'r' ? GENERAL_REGS 564 : REG_CLASS_FROM_CONSTRAINT ((unsigned char) scratch_letter, 565 scratch_constraint)); 566 567 if (reg_class_subset_p (reload_class, insn_class)) 568 { 569 gcc_assert (scratch_class == class); 570 class = NO_REGS; 571 } 572 else 573 class = insn_class; 574 575 } 576 if (class == NO_REGS) 577 sri->icode = icode; 578 else 579 sri->t_icode = icode; 580 } 581 return class; 582} 583 584 585/* If STRICT_ALIGNMENT is true we use the container type for accessing 586 volatile bitfields. This is generally the preferred behavior for memory 587 mapped peripherals on RISC architectures. 588 If STRICT_ALIGNMENT is false we use the narrowest type possible. This 589 is typically used to avoid spurious page faults and extra memory accesses 590 due to unaligned accesses on CISC architectures. */ 591 592bool 593default_narrow_bitfield (void) 594{ 595 return !STRICT_ALIGNMENT; 596} 597 598/* By default, if flag_pic is true, then neither local nor global relocs 599 should be placed in readonly memory. */ 600 601int 602default_reloc_rw_mask (void) 603{ 604 return flag_pic ? 3 : 0; 605} 606 607bool 608default_builtin_vector_alignment_reachable (tree type, bool is_packed) 609{ 610 if (is_packed) 611 return false; 612 613 /* Assuming that types whose size is > pointer-size are not guaranteed to be 614 naturally aligned. */ 615 if (tree_int_cst_compare (TYPE_SIZE (type), bitsize_int (POINTER_SIZE)) > 0) 616 return false; 617 618 /* Assuming that types whose size is <= pointer-size 619 are naturally aligned. */ 620 return true; 621} 622 623#include "gt-targhooks.h" 624