gcc/target.h

   1 /* Data structure definitions for a generic GCC target.
   2    Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007
   3    Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify it
   6    under the terms of the GNU General Public License as published by the
   7    Free Software Foundation; either version 3, or (at your option) any
   8    later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; see the file COPYING3.  If not see
  17    <http://www.gnu.org/licenses/>.
  18
  19    In other words, you are welcome to use, share and improve this program.
  20    You are forbidden to forbid anyone else to use, share and improve
  21    what you give them.   Help stamp out software-hoarding!  */
  22
  23
  24 /* This file contains a data structure that describes a GCC target.
  25    At present it is incomplete, but in future it should grow to
  26    contain most or all target machine and target O/S specific
  27    information.
  28
  29    This structure has its initializer declared in target-def.h in the
  30    form of large macro TARGET_INITIALIZER that expands to many smaller
  31    macros.
  32
  33    The smaller macros each initialize one component of the structure,
  34    and each has a default.  Each target should have a file that
  35    includes target.h and target-def.h, and overrides any inappropriate
  36    defaults by undefining the relevant macro and defining a suitable
  37    replacement.  That file should then contain the definition of
  38    "targetm" like so:
  39
  40    struct gcc_target targetm = TARGET_INITIALIZER;
  41
  42    Doing things this way allows us to bring together everything that
  43    defines a GCC target.  By supplying a default that is appropriate
  44    to most targets, we can easily add new items without needing to
  45    edit dozens of target configuration files.  It should also allow us
  46    to gradually reduce the amount of conditional compilation that is
  47    scattered throughout GCC.  */
  48
  49 #ifndef GCC_TARGET_H
  50 #define GCC_TARGET_H
  51
  52 #include "tm.h"
  53 #include "insn-modes.h"
  54
  55 /* Types used by the record_gcc_switches() target function.  */
  56 typedef enum
  57 {
  58   SWITCH_TYPE_PASSED,           /* A switch passed on the command line.  */
  59   SWITCH_TYPE_ENABLED,          /* An option that is currently enabled.  */
  60   SWITCH_TYPE_DESCRIPTIVE,      /* Descriptive text, not a switch or option.  */
  61   SWITCH_TYPE_LINE_START,       /* Please emit any necessary text at the start of a line.  */
  62   SWITCH_TYPE_LINE_END          /* Please emit a line terminator.  */
  63 }
  64 print_switch_type;
  65
  66 typedef int (* print_switch_fn_type) (print_switch_type, const char *);
  67
  68 /* An example implementation for ELF targets.  Defined in varasm.c  */
  69 extern int elf_record_gcc_switches (print_switch_type type, const char *);
  70
  71 struct stdarg_info;
  72 struct spec_info_def;
  73
  74 /* The struct used by the secondary_reload target hook.  */
  75 typedef struct secondary_reload_info
  76 {
  77   /* icode is actually an enum insn_code, but we don't want to force every
  78      file that includes target.h to include optabs.h .  */
  79   int icode;
  80   int extra_cost; /* Cost for using (a) scratch register(s) to be taken
  81                      into account by copy_cost.  */
  82   /* The next two members are for the use of the backward
  83      compatibility hook.  */
  84   struct secondary_reload_info *prev_sri;
  85   int t_icode; /* Actually an enum insn_code - see above.  */
  86 } secondary_reload_info;
  87
  88 /* This is defined in sched-int.h .  */
  89 struct _dep;
  90
  91 /* This is defined in ddg.h .  */
  92 struct ddg;
  93
  94 struct gcc_target
  95 {
  96   /* Functions that output assembler for the target.  */
  97   struct asm_out
  98   {
  99     /* Opening and closing parentheses for asm expression grouping.  */
 100     const char *open_paren, *close_paren;
 101
 102     /* Assembler instructions for creating various kinds of integer object.  */
 103     const char *byte_op;
 104     struct asm_int_op
 105     {
 106       const char *hi;
 107       const char *si;
 108       const char *di;
 109       const char *ti;
 110     } aligned_op, unaligned_op;
 111
 112     /* Try to output the assembler code for an integer object whose
 113        value is given by X.  SIZE is the size of the object in bytes and
 114        ALIGNED_P indicates whether it is aligned.  Return true if
 115        successful.  Only handles cases for which BYTE_OP, ALIGNED_OP
 116        and UNALIGNED_OP are NULL.  */
 117     bool (* integer) (rtx x, unsigned int size, int aligned_p);
 118
 119     /* Output code that will globalize a label.  */
 120     void (* globalize_label) (FILE *, const char *);
 121
 122     /* Output code that will globalize a declaration.  */
 123     void (* globalize_decl_name) (FILE *, tree);
 124
 125     /* Output code that will emit a label for unwind info, if this
 126        target requires such labels.  Second argument is the decl the
 127        unwind info is associated with, third is a boolean: true if
 128        this is for exception handling, fourth is a boolean: true if
 129        this is only a placeholder for an omitted FDE.  */
 130     void (* unwind_label) (FILE *, tree, int, int);
 131
 132     /* Output code that will emit a label to divide up the exception
 133        table.  */
 134     void (* except_table_label) (FILE *);
 135
 136     /* Emit any directives required to unwind this instruction.  */
 137     void (* unwind_emit) (FILE *, rtx);
 138
 139     /* Output an internal label.  */
 140     void (* internal_label) (FILE *, const char *, unsigned long);
 141
 142     /* Emit a ttype table reference to a typeinfo object.  */
 143     bool (* ttype) (rtx);
 144
 145     /* Emit an assembler directive to set visibility for the symbol
 146        associated with the tree decl.  */
 147     void (* visibility) (tree, int);
 148
 149     /* Output the assembler code for entry to a function.  */
 150     void (* function_prologue) (FILE *, HOST_WIDE_INT);
 151
 152     /* Output the assembler code for end of prologue.  */
 153     void (* function_end_prologue) (FILE *);
 154
 155     /* Output the assembler code for start of epilogue.  */
 156     void (* function_begin_epilogue) (FILE *);
 157
 158     /* Output the assembler code for function exit.  */
 159     void (* function_epilogue) (FILE *, HOST_WIDE_INT);
 160
 161     /* Initialize target-specific sections.  */
 162     void (* init_sections) (void);
 163
 164     /* Tell assembler to change to section NAME with attributes FLAGS.
 165        If DECL is non-NULL, it is the VAR_DECL or FUNCTION_DECL with
 166        which this section is associated.  */
 167     void (* named_section) (const char *name, unsigned int flags, tree decl);
 168
 169     /* Return a mask describing how relocations should be treated when
 170        selecting sections.  Bit 1 should be set if global relocations
 171        should be placed in a read-write section; bit 0 should be set if
 172        local relocations should be placed in a read-write section.  */
 173     int (*reloc_rw_mask) (void);
 174
 175     /* Return a section for EXP.  It may be a DECL or a constant.  RELOC
 176        is nonzero if runtime relocations must be applied; bit 1 will be
 177        set if the runtime relocations require non-local name resolution.
 178        ALIGN is the required alignment of the data.  */
 179     section *(* select_section) (tree, int, unsigned HOST_WIDE_INT);
 180
 181     /* Return a section for X.  MODE is X's mode and ALIGN is its
 182        alignment in bits.  */
 183     section *(* select_rtx_section) (enum machine_mode, rtx,
 184                                      unsigned HOST_WIDE_INT);
 185
 186     /* Select a unique section name for DECL.  RELOC is the same as
 187        for SELECT_SECTION.  */
 188     void (* unique_section) (tree, int);
 189
 190     /* Return the readonly data section associated with function DECL.  */
 191     section *(* function_rodata_section) (tree);
 192
 193     /* Output a constructor for a symbol with a given priority.  */
 194     void (* constructor) (rtx, int);
 195
 196     /* Output a destructor for a symbol with a given priority.  */
 197     void (* destructor) (rtx, int);
 198
 199     /* Output the assembler code for a thunk function.  THUNK_DECL is the
 200        declaration for the thunk function itself, FUNCTION is the decl for
 201        the target function.  DELTA is an immediate constant offset to be
 202        added to THIS.  If VCALL_OFFSET is nonzero, the word at
 203        *(*this + vcall_offset) should be added to THIS.  */
 204     void (* output_mi_thunk) (FILE *file, tree thunk_decl,
 205                               HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset,
 206                               tree function_decl);
 207
 208     /* Determine whether output_mi_thunk would succeed.  */
 209     /* ??? Ideally, this hook would not exist, and success or failure
 210        would be returned from output_mi_thunk directly.  But there's
 211        too much undo-able setup involved in invoking output_mi_thunk.
 212        Could be fixed by making output_mi_thunk emit rtl instead of
 213        text to the output file.  */
 214     bool (* can_output_mi_thunk) (const_tree thunk_decl, HOST_WIDE_INT delta,
 215                                   HOST_WIDE_INT vcall_offset,
 216                                   const_tree function_decl);
 217
 218     /* Output any boilerplate text needed at the beginning of a
 219        translation unit.  */
 220     void (*file_start) (void);
 221
 222     /* Output any boilerplate text needed at the end of a
 223        translation unit.  */
 224     void (*file_end) (void);
 225
 226     /* Output an assembler pseudo-op to declare a library function name
 227        external.  */
 228     void (*external_libcall) (rtx);
 229
 230     /* Output an assembler directive to mark decl live. This instructs
 231         linker to not dead code strip this symbol.  */
 232     void (*mark_decl_preserved) (const char *);
 233
 234     /* Output a record of the command line switches that have been passed.  */
 235     print_switch_fn_type record_gcc_switches;
 236     /* The name of the section that the example ELF implementation of
 237        record_gcc_switches will use to store the information.  Target
 238        specific versions of record_gcc_switches may or may not use
 239        this information.  */
 240     const char * record_gcc_switches_section;
 241
 242     /* Output the definition of a section anchor.  */
 243     void (*output_anchor) (rtx);
 244
 245     /* Output a DTP-relative reference to a TLS symbol.  */
 246     void (*output_dwarf_dtprel) (FILE *file, int size, rtx x);
 247
 248   } asm_out;
 249
 250   /* Functions relating to instruction scheduling.  */
 251   struct sched
 252   {
 253     /* Given the current cost, COST, of an insn, INSN, calculate and
 254        return a new cost based on its relationship to DEP_INSN through
 255        the dependence LINK.  The default is to make no adjustment.  */
 256     int (* adjust_cost) (rtx insn, rtx link, rtx dep_insn, int cost);
 257
 258     /* Adjust the priority of an insn as you see fit.  Returns the new
 259        priority.  */
 260     int (* adjust_priority) (rtx, int);
 261
 262     /* Function which returns the maximum number of insns that can be
 263        scheduled in the same machine cycle.  This must be constant
 264        over an entire compilation.  The default is 1.  */
 265     int (* issue_rate) (void);
 266
 267     /* Calculate how much this insn affects how many more insns we
 268        can emit this cycle.  Default is they all cost the same.  */
 269     int (* variable_issue) (FILE *, int, rtx, int);
 270
 271     /* Initialize machine-dependent scheduling code.  */
 272     void (* md_init) (FILE *, int, int);
 273
 274     /* Finalize machine-dependent scheduling code.  */
 275     void (* md_finish) (FILE *, int);
 276
 277     /* Initialize machine-dependent function while scheduling code.  */
 278     void (* md_init_global) (FILE *, int, int);
 279
 280     /* Finalize machine-dependent function wide scheduling code.  */
 281     void (* md_finish_global) (FILE *, int);
 282
 283     /* Reorder insns in a machine-dependent fashion, in two different
 284        places.  Default does nothing.  */
 285     int (* reorder) (FILE *, int, rtx *, int *, int);
 286     int (* reorder2) (FILE *, int, rtx *, int *, int);
 287
 288     /* The following member value is a pointer to a function called
 289        after evaluation forward dependencies of insns in chain given
 290        by two parameter values (head and tail correspondingly).  */
 291     void (* dependencies_evaluation_hook) (rtx, rtx);
 292
 293     /* The values of the following four members are pointers to
 294        functions used to simplify the automaton descriptions.
 295        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 296        returning insns which are used to change the pipeline hazard
 297        recognizer state when the new simulated processor cycle
 298        correspondingly starts and finishes.  The function defined by
 299        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 300        to initialize the corresponding insns.  The default values of
 301        the members result in not changing the automaton state when
 302        the new simulated processor cycle correspondingly starts and
 303        finishes.  */
 304     void (* init_dfa_pre_cycle_insn) (void);
 305     rtx (* dfa_pre_cycle_insn) (void);
 306     void (* init_dfa_post_cycle_insn) (void);
 307     rtx (* dfa_post_cycle_insn) (void);
 308
 309     /* The values of the following two members are pointers to
 310        functions used to simplify the automaton descriptions.
 311        dfa_pre_advance_cycle and dfa_post_advance_cycle are getting called
 312        immediately before and after cycle is advanced.  */
 313     void (* dfa_pre_advance_cycle) (void);
 314     void (* dfa_post_advance_cycle) (void);
 315
 316     /* The following member value is a pointer to a function returning value
 317        which defines how many insns in queue `ready' will we try for
 318        multi-pass scheduling.  If the member value is nonzero and the
 319        function returns positive value, the DFA based scheduler will make
 320        multi-pass scheduling for the first cycle.  In other words, we will
 321        try to choose ready insn which permits to start maximum number of
 322        insns on the same cycle.  */
 323     int (* first_cycle_multipass_dfa_lookahead) (void);
 324
 325     /* The following member value is pointer to a function controlling
 326        what insns from the ready insn queue will be considered for the
 327        multipass insn scheduling.  If the hook returns zero for insn
 328        passed as the parameter, the insn will be not chosen to be
 329        issued.  */
 330     int (* first_cycle_multipass_dfa_lookahead_guard) (rtx);
 331
 332     /* The following member value is pointer to a function called by
 333        the insn scheduler before issuing insn passed as the third
 334        parameter on given cycle.  If the hook returns nonzero, the
 335        insn is not issued on given processors cycle.  Instead of that,
 336        the processor cycle is advanced.  If the value passed through
 337        the last parameter is zero, the insn ready queue is not sorted
 338        on the new cycle start as usually.  The first parameter passes
 339        file for debugging output.  The second one passes the scheduler
 340        verbose level of the debugging output.  The forth and the fifth
 341        parameter values are correspondingly processor cycle on which
 342        the previous insn has been issued and the current processor
 343        cycle.  */
 344     int (* dfa_new_cycle) (FILE *, int, rtx, int, int, int *);
 345
 346     /* The following member value is a pointer to a function called by the
 347        insn scheduler.  It should return true if there exists a dependence
 348        which is considered costly by the target, between the insn
 349        DEP_PRO (&_DEP), and the insn DEP_CON (&_DEP).  The first parameter is
 350        the dep that represents the dependence between the two insns.  The
 351        second argument is the cost of the dependence as estimated by
 352        the scheduler.  The last argument is the distance in cycles
 353        between the already scheduled insn (first parameter) and the
 354        the second insn (second parameter).  */
 355     bool (* is_costly_dependence) (struct _dep *_dep, int, int);
 356
 357     /* The following member value is a pointer to a function called
 358        by the insn scheduler. This hook is called to notify the backend
 359        that new instructions were emitted.  */
 360     void (* h_i_d_extended) (void);
 361
 362     /* The following member value is a pointer to a function called
 363        by the insn scheduler.
 364        The first parameter is an instruction, the second parameter is the type
 365        of the requested speculation, and the third parameter is a pointer to the
 366        speculative pattern of the corresponding type (set if return value == 1).
 367        It should return
 368        -1, if there is no pattern, that will satisfy the requested speculation
 369        type,
 370        0, if current pattern satisfies the requested speculation type,
 371        1, if pattern of the instruction should be changed to the newly
 372        generated one.  */
 373     int (* speculate_insn) (rtx, int, rtx *);
 374
 375     /* The following member value is a pointer to a function called
 376        by the insn scheduler.  It should return true if the check instruction
 377        corresponding to the instruction passed as the parameter needs a
 378        recovery block.  */
 379     bool (* needs_block_p) (const_rtx);
 380
 381     /* The following member value is a pointer to a function called
 382        by the insn scheduler.  It should return a pattern for the check
 383        instruction.
 384        The first parameter is a speculative instruction, the second parameter
 385        is the label of the corresponding recovery block (or null, if it is a
 386        simple check).  If the mutation of the check is requested (e.g. from
 387        ld.c to chk.a), the third parameter is true - in this case the first
 388        parameter is the previous check.  */
 389     rtx (* gen_check) (rtx, rtx, bool);
 390
 391     /* The following member value is a pointer to a function controlling
 392        what insns from the ready insn queue will be considered for the
 393        multipass insn scheduling.  If the hook returns zero for the insn
 394        passed as the parameter, the insn will not be chosen to be
 395        issued.  This hook is used to discard speculative instructions,
 396        that stand at the first position of the ready list.  */
 397     bool (* first_cycle_multipass_dfa_lookahead_guard_spec) (const_rtx);
 398
 399     /* The following member value is a pointer to a function that provides
 400        information about the speculation capabilities of the target.
 401        The parameter is a pointer to spec_info variable.  */
 402     void (* set_sched_flags) (struct spec_info_def *);
 403
 404     /* The following member value is a pointer to a function that provides
 405        information about the target resource-based lower bound which is
 406        used by the swing modulo scheduler.  The parameter is a pointer
 407        to ddg variable.  */
 408     int (* sms_res_mii) (struct ddg *);
 409   } sched;
 410
 411   /* Functions relating to vectorization.  */
 412   struct vectorize
 413   {
 414     /* The following member value is a pointer to a function called
 415        by the vectorizer, and return the decl of the target builtin
 416        function.  */
 417     tree (* builtin_mask_for_load) (void);
 418
 419     /* Returns a code for builtin that realizes vectorized version of
 420        function, or NULL_TREE if not available.  */
 421     tree (* builtin_vectorized_function) (unsigned, tree, tree);
 422
 423     /* Returns a code for builtin that realizes vectorized version of
 424        conversion, or NULL_TREE if not available.  */
 425     tree (* builtin_conversion) (unsigned, tree);
 426
 427     /* Target builtin that implements vector widening multiplication.
 428        builtin_mul_widen_eve computes the element-by-element products
 429        for the even elements, and builtin_mul_widen_odd computes the
 430        element-by-element products for the odd elements.  */
 431     tree (* builtin_mul_widen_even) (tree);
 432     tree (* builtin_mul_widen_odd) (tree);
 433
 434     /* Returns the cost to be added to the overheads involved with
 435        executing the vectorized version of a loop.  */
 436     int (*builtin_vectorization_cost) (bool);
 437
 438     /* Return true if vector alignment is reachable (by peeling N
 439        iterations) for the given type.  */
 440     bool (* vector_alignment_reachable) (const_tree, bool);
 441   } vectorize;
 442
 443   /* The initial value of target_flags.  */
 444   int default_target_flags;
 445
 446   /* Handle target switch CODE (an OPT_* value).  ARG is the argument
 447      passed to the switch; it is NULL if no argument was.  VALUE is the
 448      value of ARG if CODE specifies a UInteger option, otherwise it is
 449      1 if the positive form of the switch was used and 0 if the negative
 450      form was.  Return true if the switch was valid.  */
 451   bool (* handle_option) (size_t code, const char *arg, int value);
 452
 453   /* Display extra, target specific information in response to a
 454      --target-help switch.  */
 455   void (* target_help) (void);
 456
 457   /* Return machine mode for filter value.  */
 458   enum machine_mode (* eh_return_filter_mode) (void);
 459
 460   /* Return machine mode for libgcc expanded cmp instructions.  */
 461   enum machine_mode (* libgcc_cmp_return_mode) (void);
 462
 463   /* Return machine mode for libgcc expanded shift instructions.  */
 464   enum machine_mode (* libgcc_shift_count_mode) (void);
 465
 466   /* Given two decls, merge their attributes and return the result.  */
 467   tree (* merge_decl_attributes) (tree, tree);
 468
 469   /* Given two types, merge their attributes and return the result.  */
 470   tree (* merge_type_attributes) (tree, tree);
 471
 472   /* Table of machine attributes and functions to handle them.
 473      Ignored if NULL.  */
 474   const struct attribute_spec *attribute_table;
 475
 476   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 477      one if they are compatible and two if they are nearly compatible
 478      (which causes a warning to be generated).  */
 479   int (* comp_type_attributes) (const_tree type1, const_tree type2);
 480
 481   /* Assign default attributes to the newly defined TYPE.  */
 482   void (* set_default_type_attributes) (tree type);
 483
 484   /* Insert attributes on the newly created DECL.  */
 485   void (* insert_attributes) (tree decl, tree *attributes);
 486
 487   /* Return true if FNDECL (which has at least one machine attribute)
 488      can be inlined despite its machine attributes, false otherwise.  */
 489   bool (* function_attribute_inlinable_p) (const_tree fndecl);
 490
 491   /* Return true if bitfields in RECORD_TYPE should follow the
 492      Microsoft Visual C++ bitfield layout rules.  */
 493   bool (* ms_bitfield_layout_p) (const_tree record_type);
 494
 495   /* True if the target supports decimal floating point.  */
 496   bool (* decimal_float_supported_p) (void);
 497
 498   /* True if the target supports fixed-point.  */
 499   bool (* fixed_point_supported_p) (void);
 500
 501   /* Return true if anonymous bitfields affect structure alignment.  */
 502   bool (* align_anon_bitfield) (void);
 503
 504   /* Return true if volatile bitfields should use the narrowest type possible.
 505      Return false if they should use the container type.  */
 506   bool (* narrow_volatile_bitfield) (void);
 507
 508   /* Set up target-specific built-in functions.  */
 509   void (* init_builtins) (void);
 510
 511   /* Expand a target-specific builtin.  */
 512   rtx (* expand_builtin) (tree exp, rtx target, rtx subtarget,
 513                           enum machine_mode mode, int ignore);
 514
 515   /* Select a replacement for a target-specific builtin.  This is done
 516      *before* regular type checking, and so allows the target to implement
 517      a crude form of function overloading.  The result is a complete
 518      expression that implements the operation.  */
 519   tree (*resolve_overloaded_builtin) (tree decl, tree params);
 520
 521   /* Fold a target-specific builtin.  */
 522   tree (* fold_builtin) (tree fndecl, tree arglist, bool ignore);
 523
 524   /* Returns a code for a target-specific builtin that implements
 525      reciprocal of the function, or NULL_TREE if not available.  */
 526   tree (* builtin_reciprocal) (unsigned, bool, bool);
 527
 528   /* For a vendor-specific TYPE, return a pointer to a statically-allocated
 529      string containing the C++ mangling for TYPE.  In all other cases, return
 530      NULL.  */
 531   const char * (* mangle_type) (const_tree type);
 532
 533   /* Make any adjustments to libfunc names needed for this target.  */
 534   void (* init_libfuncs) (void);
 535
 536   /* Given a decl, a section name, and whether the decl initializer
 537      has relocs, choose attributes for the section.  */
 538   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 539   unsigned int (* section_type_flags) (tree, const char *, int);
 540
 541   /* True if new jumps cannot be created, to replace existing ones or
 542      not, at the current point in the compilation.  */
 543   bool (* cannot_modify_jumps_p) (void);
 544
 545   /* Return a register class for which branch target register
 546      optimizations should be applied.  */
 547   int (* branch_target_register_class) (void);
 548
 549   /* Return true if branch target register optimizations should include
 550      callee-saved registers that are not already live during the current
 551      function.  AFTER_PE_GEN is true if prologues and epilogues have
 552      already been generated.  */
 553   bool (* branch_target_register_callee_saved) (bool after_pe_gen);
 554
 555   /* True if the constant X cannot be placed in the constant pool.  */
 556   bool (* cannot_force_const_mem) (rtx);
 557
 558   /* True if the insn X cannot be duplicated.  */
 559   bool (* cannot_copy_insn_p) (rtx);
 560
 561   /* True if X is considered to be commutative.  */
 562   bool (* commutative_p) (const_rtx, int);
 563
 564   /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS.  */
 565   rtx (* delegitimize_address) (rtx);
 566
 567   /* True if the given constant can be put into an object_block.  */
 568   bool (* use_blocks_for_constant_p) (enum machine_mode, const_rtx);
 569
 570   /* The minimum and maximum byte offsets for anchored addresses.  */
 571   HOST_WIDE_INT min_anchor_offset;
 572   HOST_WIDE_INT max_anchor_offset;
 573
 574   /* True if section anchors can be used to access the given symbol.  */
 575   bool (* use_anchors_for_symbol_p) (const_rtx);
 576
 577   /* True if it is OK to do sibling call optimization for the specified
 578      call expression EXP.  DECL will be the called function, or NULL if
 579      this is an indirect call.  */
 580   bool (*function_ok_for_sibcall) (tree decl, tree exp);
 581
 582   /* Establish appropriate back-end context for processing the function
 583      FNDECL.  The argument might be NULL to indicate processing at top
 584      level, outside of any function scope.  */
 585   void (*set_current_function) (tree fndecl);
 586
 587   /* True if EXP should be placed in a "small data" section.  */
 588   bool (* in_small_data_p) (const_tree);
 589
 590   /* True if EXP names an object for which name resolution must resolve
 591      to the current module.  */
 592   bool (* binds_local_p) (const_tree);
 593
 594   /* Modify and return the identifier of a DECL's external name,
 595      originally identified by ID, as required by the target,
 596     (eg, append @nn to windows32 stdcall function names).
 597      The default is to return ID without modification. */
 598    tree (* mangle_decl_assembler_name) (tree decl, tree  id);
 599
 600   /* Do something target-specific to record properties of the DECL into
 601      the associated SYMBOL_REF.  */
 602   void (* encode_section_info) (tree, rtx, int);
 603
 604   /* Undo the effects of encode_section_info on the symbol string.  */
 605   const char * (* strip_name_encoding) (const char *);
 606
 607   /* If shift optabs for MODE are known to always truncate the shift count,
 608      return the mask that they apply.  Return 0 otherwise.  */
 609   unsigned HOST_WIDE_INT (* shift_truncation_mask) (enum machine_mode mode);
 610
 611   /* Return the number of divisions in the given MODE that should be present,
 612      so that it is profitable to turn the division into a multiplication by
 613      the reciprocal.  */
 614   unsigned int (* min_divisions_for_recip_mul) (enum machine_mode mode);
 615
 616   /* If the representation of integral MODE is such that values are
 617      always sign-extended to a wider mode MODE_REP then return
 618      SIGN_EXTEND.  Return UNKNOWN otherwise.  */
 619   /* Note that the return type ought to be RTX_CODE, but that's not
 620      necessarily defined at this point.  */
 621   int (* mode_rep_extended) (enum machine_mode mode,
 622                              enum machine_mode mode_rep);
 623
 624   /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))).  */
 625   bool (* valid_pointer_mode) (enum machine_mode mode);
 626
 627   /* True if MODE is valid for the target.  By "valid", we mean able to
 628      be manipulated in non-trivial ways.  In particular, this means all
 629      the arithmetic is supported.  */
 630   bool (* scalar_mode_supported_p) (enum machine_mode mode);
 631
 632   /* Similarly for vector modes.  "Supported" here is less strict.  At
 633      least some operations are supported; need to check optabs or builtins
 634      for further details.  */
 635   bool (* vector_mode_supported_p) (enum machine_mode mode);
 636
 637   /* True if a vector is opaque.  */
 638   bool (* vector_opaque_p) (const_tree);
 639
 640   /* Compute a (partial) cost for rtx X.  Return true if the complete
 641      cost has been computed, and false if subexpressions should be
 642      scanned.  In either case, *TOTAL contains the cost result.  */
 643   /* Note that CODE and OUTER_CODE ought to be RTX_CODE, but that's
 644      not necessarily defined at this point.  */
 645   bool (* rtx_costs) (rtx x, int code, int outer_code, int *total);
 646
 647   /* Compute the cost of X, used as an address.  Never called with
 648      invalid addresses.  */
 649   int (* address_cost) (rtx x);
 650
 651   /* Return where to allocate pseudo for a given hard register initial
 652      value.  */
 653   rtx (* allocate_initial_value) (rtx x);
 654
 655   /* Return nonzero if evaluating UNSPEC[_VOLATILE] X might cause a trap.
 656      FLAGS has the same meaning as in rtlanal.c: may_trap_p_1.  */
 657   int (* unspec_may_trap_p) (const_rtx x, unsigned flags);
 658
 659   /* Given a register, this hook should return a parallel of registers
 660      to represent where to find the register pieces.  Define this hook
 661      if the register and its mode are represented in Dwarf in
 662      non-contiguous locations, or if the register should be
 663      represented in more than one register in Dwarf.  Otherwise, this
 664      hook should return NULL_RTX.  */
 665   rtx (* dwarf_register_span) (rtx);
 666
 667   /* If expand_builtin_init_dwarf_reg_sizes needs to fill in table
 668      entries not corresponding directly to registers below
 669      FIRST_PSEUDO_REGISTER, this hook should generate the necessary
 670      code, given the address of the table.  */
 671   void (* init_dwarf_reg_sizes_extra) (tree);
 672
 673   /* Fetch the fixed register(s) which hold condition codes, for
 674      targets where it makes sense to look for duplicate assignments to
 675      the condition codes.  This should return true if there is such a
 676      register, false otherwise.  The arguments should be set to the
 677      fixed register numbers.  Up to two condition code registers are
 678      supported.  If there is only one for this target, the int pointed
 679      at by the second argument should be set to -1.  */
 680   bool (* fixed_condition_code_regs) (unsigned int *, unsigned int *);
 681
 682   /* If two condition code modes are compatible, return a condition
 683      code mode which is compatible with both, such that a comparison
 684      done in the returned mode will work for both of the original
 685      modes.  If the condition code modes are not compatible, return
 686      VOIDmode.  */
 687   enum machine_mode (* cc_modes_compatible) (enum machine_mode,
 688                                              enum machine_mode);
 689
 690   /* Do machine-dependent code transformations.  Called just before
 691      delayed-branch scheduling.  */
 692   void (* machine_dependent_reorg) (void);
 693
 694   /* Create the __builtin_va_list type.  */
 695   tree (* build_builtin_va_list) (void);
 696
 697   /* Expand the __builtin_va_start builtin.  */
 698   void (* expand_builtin_va_start) (tree valist, rtx nextarg);
 699
 700   /* Gimplifies a VA_ARG_EXPR.  */
 701   tree (* gimplify_va_arg_expr) (tree valist, tree type, tree *pre_p,
 702                                  tree *post_p);
 703
 704   /* Validity-checking routines for PCH files, target-specific.
 705      get_pch_validity returns a pointer to the data to be stored,
 706      and stores the size in its argument.  pch_valid_p gets the same
 707      information back and returns NULL if the PCH is valid,
 708      or an error message if not.
 709   */
 710   void * (* get_pch_validity) (size_t *);
 711   const char * (* pch_valid_p) (const void *, size_t);
 712
 713   /* If nonnull, this function checks whether a PCH file with the
 714      given set of target flags can be used.  It returns NULL if so,
 715      otherwise it returns an error message.  */
 716   const char *(*check_pch_target_flags) (int);
 717
 718   /* True if the compiler should give an enum type only as many
 719      bytes as it takes to represent the range of possible values of
 720      that type.  */
 721   bool (* default_short_enums) (void);
 722
 723   /* This target hook returns an rtx that is used to store the address
 724      of the current frame into the built-in setjmp buffer.  */
 725   rtx (* builtin_setjmp_frame_value) (void);
 726
 727   /* This target hook should add STRING_CST trees for any hard regs
 728      the port wishes to automatically clobber for an asm.  */
 729   tree (* md_asm_clobbers) (tree, tree, tree);
 730
 731   /* This target hook allows the backend to specify a calling convention
 732      in the debug information.  This function actually returns an
 733      enum dwarf_calling_convention, but because of forward declarations
 734      and not wanting to include dwarf2.h everywhere target.h is included
 735      the function is being declared as an int.  */
 736   int (* dwarf_calling_convention) (const_tree);
 737
 738   /* This target hook allows the backend to emit frame-related insns that
 739      contain UNSPECs or UNSPEC_VOLATILEs.  The call frame debugging info
 740      engine will invoke it on insns of the form
 741        (set (reg) (unspec [...] UNSPEC_INDEX))
 742      and
 743        (set (reg) (unspec_volatile [...] UNSPECV_INDEX))
 744      to let the backend emit the call frame instructions.  */
 745   void (* dwarf_handle_frame_unspec) (const char *, rtx, int);
 746
 747   /* Perform architecture specific checking of statements gimplified
 748      from VA_ARG_EXPR.  LHS is left hand side of MODIFY_EXPR, RHS
 749      is right hand side.  Returns true if the statements doesn't need
 750      to be checked for va_list references.  */
 751   bool (* stdarg_optimize_hook) (struct stdarg_info *ai, const_tree lhs, const_tree rhs);
 752
 753   /* This target hook allows the operating system to override the DECL
 754      that represents the external variable that contains the stack
 755      protection guard variable.  The type of this DECL is ptr_type_node.  */
 756   tree (* stack_protect_guard) (void);
 757
 758   /* This target hook allows the operating system to override the CALL_EXPR
 759      that is invoked when a check vs the guard variable fails.  */
 760   tree (* stack_protect_fail) (void);
 761
 762   /* Returns NULL if target supports the insn within a doloop block,
 763      otherwise it returns an error message.  */
 764   const char * (*invalid_within_doloop) (const_rtx);
 765
 766   /* DECL is a variable or function with __attribute__((dllimport))
 767      specified.  Use this hook if the target needs to add extra validation
 768      checks to  handle_dll_attribute ().  */
 769   bool (* valid_dllimport_attribute_p) (const_tree decl);
 770
 771   /* Functions relating to calls - argument passing, returns, etc.  */
 772   struct calls {
 773     bool (*promote_function_args) (const_tree fntype);
 774     bool (*promote_function_return) (const_tree fntype);
 775     bool (*promote_prototypes) (const_tree fntype);
 776     rtx (*struct_value_rtx) (tree fndecl, int incoming);
 777     bool (*return_in_memory) (const_tree type, const_tree fndecl);
 778     bool (*return_in_msb) (const_tree type);
 779
 780     /* Return true if a parameter must be passed by reference.  TYPE may
 781        be null if this is a libcall.  CA may be null if this query is
 782        from __builtin_va_arg.  */
 783     bool (*pass_by_reference) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 784                                const_tree type, bool named_arg);
 785
 786     rtx (*expand_builtin_saveregs) (void);
 787     /* Returns pretend_argument_size.  */
 788     void (*setup_incoming_varargs) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 789                                     tree type, int *pretend_arg_size,
 790                                     int second_time);
 791     bool (*strict_argument_naming) (CUMULATIVE_ARGS *ca);
 792     /* Returns true if we should use
 793        targetm.calls.setup_incoming_varargs() and/or
 794        targetm.calls.strict_argument_naming().  */
 795     bool (*pretend_outgoing_varargs_named) (CUMULATIVE_ARGS *ca);
 796
 797     /* Given a complex type T, return true if a parameter of type T
 798        should be passed as two scalars.  */
 799     bool (* split_complex_arg) (const_tree type);
 800
 801     /* Return true if type T, mode MODE, may not be passed in registers,
 802        but must be passed on the stack.  */
 803     /* ??? This predicate should be applied strictly after pass-by-reference.
 804        Need audit to verify that this is the case.  */
 805     bool (* must_pass_in_stack) (enum machine_mode mode, const_tree t);
 806
 807     /* Return true if type TYPE, mode MODE, which is passed by reference,
 808        should have the object copy generated by the callee rather than
 809        the caller.  It is never called for TYPE requiring constructors.  */
 810     bool (* callee_copies) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 811                             const_tree type, bool named);
 812
 813     /* Return zero for arguments passed entirely on the stack or entirely
 814        in registers.  If passed in both, return the number of bytes passed
 815        in registers; the balance is therefore passed on the stack.  */
 816     int (* arg_partial_bytes) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 817                                tree type, bool named);
 818
 819     /* Return the diagnostic message string if function without a prototype
 820        is not allowed for this 'val' argument; NULL otherwise. */
 821     const char *(*invalid_arg_for_unprototyped_fn) (const_tree typelist,
 822                                                     const_tree funcdecl,
 823                                                     const_tree val);
 824
 825     /* Return an rtx for the return value location of the function
 826        specified by FN_DECL_OR_TYPE with a return type of RET_TYPE.  */
 827     rtx (*function_value) (const_tree ret_type, const_tree fn_decl_or_type,
 828                            bool outgoing);
 829
 830     /* Return an rtx for the argument pointer incoming to the
 831        current function.  */
 832     rtx (*internal_arg_pointer) (void);
 833   } calls;
 834
 835   /* Return the diagnostic message string if conversion from FROMTYPE
 836      to TOTYPE is not allowed, NULL otherwise.  */
 837   const char *(*invalid_conversion) (const_tree fromtype, const_tree totype);
 838
 839   /* Return the diagnostic message string if the unary operation OP is
 840      not permitted on TYPE, NULL otherwise.  */
 841   const char *(*invalid_unary_op) (int op, const_tree type);
 842
 843   /* Return the diagnostic message string if the binary operation OP
 844      is not permitted on TYPE1 and TYPE2, NULL otherwise.  */
 845   const char *(*invalid_binary_op) (int op, const_tree type1, const_tree type2);
 846
 847   /* Return the class for a secondary reload, and fill in extra information.  */
 848   enum reg_class (*secondary_reload) (bool, rtx, enum reg_class,
 849                                       enum machine_mode,
 850                                       struct secondary_reload_info *);
 851
 852   /* This target hook allows the backend to perform additional
 853      processing while initializing for variable expansion.  */
 854   void (* expand_to_rtl_hook) (void);
 855
 856   /* This target hook allows the backend to perform additional
 857      instantiations on rtx that are not actually in insns yet,
 858      but will be later.  */
 859   void (* instantiate_decls) (void);
 860
 861   /* Functions specific to the C family of frontends.  */
 862   struct c {
 863     /* Return machine mode for non-standard suffix
 864        or VOIDmode if non-standard suffixes are unsupported.  */
 865     enum machine_mode (*mode_for_suffix) (char);
 866   } c;
 867
 868   /* Functions specific to the C++ frontend.  */
 869   struct cxx {
 870     /* Return the integer type used for guard variables.  */
 871     tree (*guard_type) (void);
 872     /* Return true if only the low bit of the guard should be tested.  */
 873     bool (*guard_mask_bit) (void);
 874     /* Returns the size of the array cookie for an array of type.  */
 875     tree (*get_cookie_size) (tree);
 876     /* Returns true if the element size should be stored in the
 877        array cookie.  */
 878     bool (*cookie_has_size) (void);
 879     /* Allows backends to perform additional processing when
 880        deciding if a class should be exported or imported.  */
 881     int (*import_export_class) (tree, int);
 882     /* Returns true if constructors and destructors return "this".  */
 883     bool (*cdtor_returns_this) (void);
 884     /* Returns true if the key method for a class can be an inline
 885        function, so long as it is not declared inline in the class
 886        itself.  Returning true is the behavior required by the Itanium
 887        C++ ABI.  */
 888     bool (*key_method_may_be_inline) (void);
 889     /* DECL is a virtual table, virtual table table, typeinfo object,
 890        or other similar implicit class data object that will be
 891        emitted with external linkage in this translation unit.  No ELF
 892        visibility has been explicitly specified.  If the target needs
 893        to specify a visibility other than that of the containing class,
 894        use this hook to set DECL_VISIBILITY and
 895        DECL_VISIBILITY_SPECIFIED.  */
 896     void (*determine_class_data_visibility) (tree decl);
 897     /* Returns true (the default) if virtual tables and other
 898        similar implicit class data objects are always COMDAT if they
 899        have external linkage.  If this hook returns false, then
 900        class data for classes whose virtual table will be emitted in
 901        only one translation unit will not be COMDAT.  */
 902     bool (*class_data_always_comdat) (void);
 903     /* Returns true (the default) if the RTTI for the basic types,
 904        which is always defined in the C++ runtime, should be COMDAT;
 905        false if it should not be COMDAT.  */
 906     bool (*library_rtti_comdat) (void);
 907     /* Returns true if __aeabi_atexit should be used to register static
 908        destructors.  */
 909     bool (*use_aeabi_atexit) (void);
 910     /* Returns true if target may use atexit in the same manner as
 911     __cxa_atexit  to register static destructors.  */
 912     bool (*use_atexit_for_cxa_atexit) (void);
 913     /* TYPE is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that
 914        has just been defined.  Use this hook to make adjustments to the
 915        class  (eg, tweak visibility or perform any other required
 916        target modifications).  */
 917     void (*adjust_class_at_definition) (tree type);
 918   } cxx;
 919
 920   /* Functions and data for emulated TLS support.  */
 921   struct emutls {
 922     /* Name of the address and common functions.  */
 923     const char *get_address;
 924     const char *register_common;
 925
 926     /* Prefixes for proxy variable and template.  */
 927     const char *var_section;
 928     const char *tmpl_section;
 929
 930     /* Prefixes for proxy variable and template.  */
 931     const char *var_prefix;
 932     const char *tmpl_prefix;
 933
 934     /* Function to generate field definitions of the proxy variable.  */
 935     tree (*var_fields) (tree, tree *);
 936
 937     /* Function to initialize a proxy variable.  */
 938     tree (*var_init) (tree, tree, tree);
 939
 940     /* Whether we are allowed to alter the usual alignment of the
 941        proxy variable.  */
 942     bool var_align_fixed;
 943
 944     /* Whether we can emit debug information for TLS vars.  */
 945     bool debug_form_tls_address;
 946   } emutls;
 947
 948   /* For targets that need to mark extra registers as live on entry to
 949      the function, they should define this target hook and set their
 950      bits in the bitmap passed in. */
 951   void (*live_on_entry) (bitmap);
 952
 953   /* True if unwinding tables should be generated by default.  */
 954   bool unwind_tables_default;
 955
 956   /* Leave the boolean fields at the end.  */
 957
 958   /* True if arbitrary sections are supported.  */
 959   bool have_named_sections;
 960
 961   /* True if we can create zeroed data by switching to a BSS section
 962      and then using ASM_OUTPUT_SKIP to allocate the space.  */
 963   bool have_switchable_bss_sections;
 964
 965   /* True if "native" constructors and destructors are supported,
 966      false if we're using collect2 for the job.  */
 967   bool have_ctors_dtors;
 968
 969   /* True if thread-local storage is supported.  */
 970   bool have_tls;
 971
 972   /* True if a small readonly data section is supported.  */
 973   bool have_srodata_section;
 974
 975   /* True if EH frame info sections should be zero-terminated.  */
 976   bool terminate_dw2_eh_frame_info;
 977
 978   /* True if #NO_APP should be emitted at the beginning of
 979      assembly output.  */
 980   bool file_start_app_off;
 981
 982   /* True if output_file_directive should be called for main_input_filename
 983      at the beginning of assembly output.  */
 984   bool file_start_file_directive;
 985
 986   /* True if #pragma redefine_extname is to be supported.  */
 987   bool handle_pragma_redefine_extname;
 988
 989   /* True if #pragma extern_prefix is to be supported.  */
 990   bool handle_pragma_extern_prefix;
 991
 992   /* True if the target is allowed to reorder memory accesses unless
 993      synchronization is explicitly requested.  */
 994   bool relaxed_ordering;
 995
 996   /* Returns true if we should generate exception tables for use with the
 997      ARM EABI.  The effects the encoding of function exception specifications.
 998    */
 999   bool arm_eabi_unwinder;
1000
1001   /* Leave the boolean fields at the end.  */
1002 };
1003
1004 extern struct gcc_target targetm;
1005
1006 struct gcc_targetcm {
1007   /* Handle target switch CODE (an OPT_* value).  ARG is the argument
1008      passed to the switch; it is NULL if no argument was.  VALUE is the
1009      value of ARG if CODE specifies a UInteger option, otherwise it is
1010      1 if the positive form of the switch was used and 0 if the negative
1011      form was.  Return true if the switch was valid.  */
1012   bool (*handle_c_option) (size_t code, const char *arg, int value);
1013 };
1014
1015 /* Each target can provide their own.  */
1016 extern struct gcc_targetcm targetcm;
1017
1018 #endif /* GCC_TARGET_H */