gcc/target.h

   1 /* Data structure definitions for a generic GCC target.
   2    Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   3
   4 This program is free software; you can redistribute it and/or modify it
   5 under the terms of the GNU General Public License as published by the
   6 Free Software Foundation; either version 2, or (at your option) any
   7 later version.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program; if not, write to the Free Software
  16 Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17
  18  In other words, you are welcome to use, share and improve this program.
  19  You are forbidden to forbid anyone else to use, share and improve
  20  what you give them.   Help stamp out software-hoarding!  */
  21
  22 /* This file contains a data structure that describes a GCC target.
  23    At present it is incomplete, but in future it should grow to
  24    contain most or all target machine and target O/S specific
  25    information.
  26
  27    This structure has its initializer declared in target-def.h in the
  28    form of large macro TARGET_INITIALIZER that expands to many smaller
  29    macros.
  30
  31    The smaller macros each initialize one component of the structure,
  32    and each has a default.  Each target should have a file that
  33    includes target.h and target-def.h, and overrides any inappropriate
  34    defaults by undefining the relevant macro and defining a suitable
  35    replacement.  That file should then contain the definition of
  36    "targetm" like so:
  37
  38    struct gcc_target targetm = TARGET_INITIALIZER;
  39
  40    Doing things this way allows us to bring together everything that
  41    defines a GCC target.  By supplying a default that is appropriate
  42    to most targets, we can easily add new items without needing to
  43    edit dozens of target configuration files.  It should also allow us
  44    to gradually reduce the amount of conditional compilation that is
  45    scattered throughout GCC.  */
  46
  47 #ifndef GCC_TARGET_H
  48 #define GCC_TARGET_H
  49
  50 #include "tm.h"
  51 #include "insn-modes.h"
  52
  53 struct stdarg_info;
  54
  55 struct gcc_target
  56 {
  57   /* Functions that output assembler for the target.  */
  58   struct asm_out
  59   {
  60     /* Opening and closing parentheses for asm expression grouping.  */
  61     const char *open_paren, *close_paren;
  62
  63     /* Assembler instructions for creating various kinds of integer object.  */
  64     const char *byte_op;
  65     struct asm_int_op
  66     {
  67       const char *hi;
  68       const char *si;
  69       const char *di;
  70       const char *ti;
  71     } aligned_op, unaligned_op;
  72
  73     /* Try to output the assembler code for an integer object whose
  74        value is given by X.  SIZE is the size of the object in bytes and
  75        ALIGNED_P indicates whether it is aligned.  Return true if
  76        successful.  Only handles cases for which BYTE_OP, ALIGNED_OP
  77        and UNALIGNED_OP are NULL.  */
  78     bool (* integer) (rtx x, unsigned int size, int aligned_p);
  79
  80     /* Output code that will globalize a label.  */
  81     void (* globalize_label) (FILE *, const char *);
  82
  83     /* Output code that will emit a label for unwind info, if this
  84        target requires such labels.  Second argument is the decl the
  85        unwind info is associated with, third is a boolean: true if
  86        this is for exception handling, fourth is a boolean: true if
  87        this is only a placeholder for an omitted FDE.  */
  88     void (* unwind_label) (FILE *, tree, int, int);
  89
  90     /* Emit any directives required to unwind this instruction.  */
  91     void (* unwind_emit) (FILE *, rtx);
  92
  93     /* Output an internal label.  */
  94     void (* internal_label) (FILE *, const char *, unsigned long);
  95
  96     /* Emit an assembler directive to set visibility for the symbol
  97        associated with the tree decl.  */
  98     void (* visibility) (tree, int);
  99
 100     /* Output the assembler code for entry to a function.  */
 101     void (* function_prologue) (FILE *, HOST_WIDE_INT);
 102
 103     /* Output the assembler code for end of prologue.  */
 104     void (* function_end_prologue) (FILE *);
 105
 106     /* Output the assembler code for start of epilogue.  */
 107     void (* function_begin_epilogue) (FILE *);
 108
 109     /* Output the assembler code for function exit.  */
 110     void (* function_epilogue) (FILE *, HOST_WIDE_INT);
 111
 112     /* Tell assembler to change to section NAME with attributes FLAGS.
 113        If DECL is non-NULL, it is the VAR_DECL or FUNCTION_DECL with
 114        which this section is associated.  */
 115     void (* named_section) (const char *name, unsigned int flags, tree decl);
 116
 117     /* Switch to the section that holds the exception table.  */
 118     void (* exception_section) (void);
 119
 120     /* Switch to the section that holds the exception frames.  */
 121     void (* eh_frame_section) (void);
 122
 123     /* Select and switch to a section for EXP.  It may be a DECL or a
 124        constant.  RELOC is nonzero if runtime relocations must be applied;
 125        bit 1 will be set if the runtime relocations require non-local
 126        name resolution.  ALIGN is the required alignment of the data.  */
 127     void (* select_section) (tree, int, unsigned HOST_WIDE_INT);
 128
 129     /* Select and switch to a section for X with MODE.  ALIGN is
 130        the desired alignment of the data.  */
 131     void (* select_rtx_section) (enum machine_mode, rtx,
 132                                  unsigned HOST_WIDE_INT);
 133
 134     /* Select a unique section name for DECL.  RELOC is the same as
 135        for SELECT_SECTION.  */
 136     void (* unique_section) (tree, int);
 137
 138     /* Tell assembler to switch to the readonly data section associated
 139        with function DECL.  */
 140     void (* function_rodata_section) (tree);
 141
 142     /* Output a constructor for a symbol with a given priority.  */
 143     void (* constructor) (rtx, int);
 144
 145     /* Output a destructor for a symbol with a given priority.  */
 146     void (* destructor) (rtx, int);
 147
 148     /* Output the assembler code for a thunk function.  THUNK_DECL is the
 149        declaration for the thunk function itself, FUNCTION is the decl for
 150        the target function.  DELTA is an immediate constant offset to be
 151        added to THIS.  If VCALL_OFFSET is nonzero, the word at
 152        *(*this + vcall_offset) should be added to THIS.  */
 153     void (* output_mi_thunk) (FILE *file, tree thunk_decl,
 154                               HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset,
 155                               tree function_decl);
 156
 157     /* Determine whether output_mi_thunk would succeed.  */
 158     /* ??? Ideally, this hook would not exist, and success or failure
 159        would be returned from output_mi_thunk directly.  But there's
 160        too much undo-able setup involved in invoking output_mi_thunk.
 161        Could be fixed by making output_mi_thunk emit rtl instead of
 162        text to the output file.  */
 163     bool (* can_output_mi_thunk) (tree thunk_decl, HOST_WIDE_INT delta,
 164                                   HOST_WIDE_INT vcall_offset,
 165                                   tree function_decl);
 166
 167     /* Output any boilerplate text needed at the beginning of a
 168        translation unit.  */
 169     void (*file_start) (void);
 170
 171     /* Output any boilerplate text needed at the end of a
 172        translation unit.  */
 173     void (*file_end) (void);
 174
 175     /* Output an assembler pseudo-op to declare a library function name
 176        external.  */
 177     void (*external_libcall) (rtx);
 178
 179      /* Output an assembler directive to mark decl live. This instructs
 180         linker to not dead code strip this symbol.  */
 181     void (*mark_decl_preserved) (const char *);
 182
 183     /* Output a DTP-relative reference to a TLS symbol.  */
 184     void (*output_dwarf_dtprel) (FILE *file, int size, rtx x);
 185
 186   } asm_out;
 187
 188   /* Functions relating to instruction scheduling.  */
 189   struct sched
 190   {
 191     /* Given the current cost, COST, of an insn, INSN, calculate and
 192        return a new cost based on its relationship to DEP_INSN through
 193        the dependence LINK.  The default is to make no adjustment.  */
 194     int (* adjust_cost) (rtx insn, rtx link, rtx def_insn, int cost);
 195
 196     /* Adjust the priority of an insn as you see fit.  Returns the new
 197        priority.  */
 198     int (* adjust_priority) (rtx, int);
 199
 200     /* Function which returns the maximum number of insns that can be
 201        scheduled in the same machine cycle.  This must be constant
 202        over an entire compilation.  The default is 1.  */
 203     int (* issue_rate) (void);
 204
 205     /* Calculate how much this insn affects how many more insns we
 206        can emit this cycle.  Default is they all cost the same.  */
 207     int (* variable_issue) (FILE *, int, rtx, int);
 208
 209     /* Initialize machine-dependent scheduling code.  */
 210     void (* md_init) (FILE *, int, int);
 211
 212     /* Finalize machine-dependent scheduling code.  */
 213     void (* md_finish) (FILE *, int);
 214
 215     /* Initialize machine-dependent function while scheduling code.  */
 216     void (* md_init_global) (FILE *, int, int);
 217
 218     /* Finalize machine-dependent function wide scheduling code.  */
 219     void (* md_finish_global) (FILE *, int);
 220
 221     /* Reorder insns in a machine-dependent fashion, in two different
 222        places.  Default does nothing.  */
 223     int (* reorder) (FILE *, int, rtx *, int *, int);
 224     int (* reorder2) (FILE *, int, rtx *, int *, int);
 225
 226     /* The following member value is a pointer to a function called
 227        after evaluation forward dependencies of insns in chain given
 228        by two parameter values (head and tail correspondingly).  */
 229     void (* dependencies_evaluation_hook) (rtx, rtx);
 230
 231     /* The values of the following four members are pointers to
 232        functions used to simplify the automaton descriptions.
 233        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 234        returning insns which are used to change the pipeline hazard
 235        recognizer state when the new simulated processor cycle
 236        correspondingly starts and finishes.  The function defined by
 237        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 238        to initialize the corresponding insns.  The default values of
 239        the members result in not changing the automaton state when
 240        the new simulated processor cycle correspondingly starts and
 241        finishes.  */
 242     void (* init_dfa_pre_cycle_insn) (void);
 243     rtx (* dfa_pre_cycle_insn) (void);
 244     void (* init_dfa_post_cycle_insn) (void);
 245     rtx (* dfa_post_cycle_insn) (void);
 246
 247     /* The following member value is a pointer to a function returning value
 248        which defines how many insns in queue `ready' will we try for
 249        multi-pass scheduling.  If the member value is nonzero and the
 250        function returns positive value, the DFA based scheduler will make
 251        multi-pass scheduling for the first cycle.  In other words, we will
 252        try to choose ready insn which permits to start maximum number of
 253        insns on the same cycle.  */
 254     int (* first_cycle_multipass_dfa_lookahead) (void);
 255
 256     /* The following member value is pointer to a function controlling
 257        what insns from the ready insn queue will be considered for the
 258        multipass insn scheduling.  If the hook returns zero for insn
 259        passed as the parameter, the insn will be not chosen to be
 260        issued.  */
 261     int (* first_cycle_multipass_dfa_lookahead_guard) (rtx);
 262
 263     /* The following member value is pointer to a function called by
 264        the insn scheduler before issuing insn passed as the third
 265        parameter on given cycle.  If the hook returns nonzero, the
 266        insn is not issued on given processors cycle.  Instead of that,
 267        the processor cycle is advanced.  If the value passed through
 268        the last parameter is zero, the insn ready queue is not sorted
 269        on the new cycle start as usually.  The first parameter passes
 270        file for debugging output.  The second one passes the scheduler
 271        verbose level of the debugging output.  The forth and the fifth
 272        parameter values are correspondingly processor cycle on which
 273        the previous insn has been issued and the current processor
 274        cycle.  */
 275     int (* dfa_new_cycle) (FILE *, int, rtx, int, int, int *);
 276
 277     /* The following member value is a pointer to a function called
 278        by the insn scheduler.  It should return true if there exists a
 279        dependence which is considered costly by the target, between
 280        the insn passed as the first parameter, and the insn passed as
 281        the second parameter.  The third parameter is the INSN_DEPEND
 282        link that represents the dependence between the two insns.  The
 283        fourth argument is the cost of the dependence as estimated by
 284        the scheduler.  The last argument is the distance in cycles
 285        between the already scheduled insn (first parameter) and the
 286        the second insn (second parameter).  */
 287     bool (* is_costly_dependence) (rtx, rtx, rtx, int, int);
 288   } sched;
 289
 290   /* Functions relating to vectorization.  */
 291   struct vectorize
 292   {
 293     /* The following member value is a pointer to a function called
 294        by the vectorizer, and return the decl of the target builtin
 295        function.  */
 296     tree (* builtin_mask_for_load) (void);
 297   } vectorize;
 298
 299   /* The initial value of target_flags.  */
 300   int default_target_flags;
 301
 302   /* Handle target switch CODE (an OPT_* value).  ARG is the argument
 303      passed to the switch; it is NULL if no argument was.  VALUE is the
 304      value of ARG if CODE specifies a UInteger option, otherwise it is
 305      1 if the positive form of the switch was used and 0 if the negative
 306      form was.  Return true if the switch was valid.  */
 307   bool (* handle_option) (size_t code, const char *arg, int value);
 308
 309   /* Return machine mode for filter value.  */
 310   enum machine_mode (* eh_return_filter_mode) (void);
 311
 312   /* Given two decls, merge their attributes and return the result.  */
 313   tree (* merge_decl_attributes) (tree, tree);
 314
 315   /* Given two types, merge their attributes and return the result.  */
 316   tree (* merge_type_attributes) (tree, tree);
 317
 318   /* Table of machine attributes and functions to handle them.
 319      Ignored if NULL.  */
 320   const struct attribute_spec *attribute_table;
 321
 322   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 323      one if they are compatible and two if they are nearly compatible
 324      (which causes a warning to be generated).  */
 325   int (* comp_type_attributes) (tree type1, tree type2);
 326
 327   /* Assign default attributes to the newly defined TYPE.  */
 328   void (* set_default_type_attributes) (tree type);
 329
 330   /* Insert attributes on the newly created DECL.  */
 331   void (* insert_attributes) (tree decl, tree *attributes);
 332
 333   /* Return true if FNDECL (which has at least one machine attribute)
 334      can be inlined despite its machine attributes, false otherwise.  */
 335   bool (* function_attribute_inlinable_p) (tree fndecl);
 336
 337   /* Return true if bitfields in RECORD_TYPE should follow the
 338      Microsoft Visual C++ bitfield layout rules.  */
 339   bool (* ms_bitfield_layout_p) (tree record_type);
 340
 341   /* Return true if anonymous bitfields affect structure alignment.  */
 342   bool (* align_anon_bitfield) (void);
 343
 344   /* Set up target-specific built-in functions.  */
 345   void (* init_builtins) (void);
 346
 347   /* Expand a target-specific builtin.  */
 348   rtx (* expand_builtin) (tree exp, rtx target, rtx subtarget,
 349                           enum machine_mode mode, int ignore);
 350
 351   /* Select a replacement for a target-specific builtin.  This is done
 352      *before* regular type checking, and so allows the target to implement
 353      a crude form of function overloading.  The result is a complete
 354      expression that implements the operation.  */
 355   tree (*resolve_overloaded_builtin) (tree decl, tree params);
 356
 357   /* Fold a target-specific builtin.  */
 358   tree (* fold_builtin) (tree fndecl, tree arglist, bool ignore);
 359
 360   /* For a vendor-specific fundamental TYPE, return a pointer to
 361      a statically-allocated string containing the C++ mangling for
 362      TYPE.  In all other cases, return NULL.  */
 363   const char * (* mangle_fundamental_type) (tree type);
 364
 365   /* Make any adjustments to libfunc names needed for this target.  */
 366   void (* init_libfuncs) (void);
 367
 368   /* Given a decl, a section name, and whether the decl initializer
 369      has relocs, choose attributes for the section.  */
 370   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 371   unsigned int (* section_type_flags) (tree, const char *, int);
 372
 373   /* True if new jumps cannot be created, to replace existing ones or
 374      not, at the current point in the compilation.  */
 375   bool (* cannot_modify_jumps_p) (void);
 376
 377   /* Return a register class for which branch target register
 378      optimizations should be applied.  */
 379   int (* branch_target_register_class) (void);
 380
 381   /* Return true if branch target register optimizations should include
 382      callee-saved registers that are not already live during the current
 383      function.  AFTER_PE_GEN is true if prologues and epilogues have
 384      already been generated.  */
 385   bool (* branch_target_register_callee_saved) (bool after_pe_gen);
 386
 387   /* True if the constant X cannot be placed in the constant pool.  */
 388   bool (* cannot_force_const_mem) (rtx);
 389
 390   /* True if the insn X cannot be duplicated.  */
 391   bool (* cannot_copy_insn_p) (rtx);
 392
 393   /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS.  */
 394   rtx (* delegitimize_address) (rtx);
 395
 396   /* True if it is OK to do sibling call optimization for the specified
 397      call expression EXP.  DECL will be the called function, or NULL if
 398      this is an indirect call.  */
 399   bool (*function_ok_for_sibcall) (tree decl, tree exp);
 400
 401   /* True if EXP should be placed in a "small data" section.  */
 402   bool (* in_small_data_p) (tree);
 403
 404   /* True if EXP names an object for which name resolution must resolve
 405      to the current module.  */
 406   bool (* binds_local_p) (tree);
 407
 408   /* Do something target-specific to record properties of the DECL into
 409      the associated SYMBOL_REF.  */
 410   void (* encode_section_info) (tree, rtx, int);
 411
 412   /* Undo the effects of encode_section_info on the symbol string.  */
 413   const char * (* strip_name_encoding) (const char *);
 414
 415   /* If shift optabs for MODE are known to always truncate the shift count,
 416      return the mask that they apply.  Return 0 otherwise.  */
 417   unsigned HOST_WIDE_INT (* shift_truncation_mask) (enum machine_mode mode);
 418
 419   /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))).  */
 420   bool (* valid_pointer_mode) (enum machine_mode mode);
 421
 422   /* True if MODE is valid for the target.  By "valid", we mean able to
 423      be manipulated in non-trivial ways.  In particular, this means all
 424      the arithmetic is supported.  */
 425   bool (* scalar_mode_supported_p) (enum machine_mode mode);
 426
 427   /* Similarly for vector modes.  "Supported" here is less strict.  At
 428      least some operations are supported; need to check optabs or builtins
 429      for further details.  */
 430   bool (* vector_mode_supported_p) (enum machine_mode mode);
 431
 432   /* True if a vector is opaque.  */
 433   bool (* vector_opaque_p) (tree);
 434
 435   /* Compute a (partial) cost for rtx X.  Return true if the complete
 436      cost has been computed, and false if subexpressions should be
 437      scanned.  In either case, *TOTAL contains the cost result.  */
 438   /* Note that CODE and OUTER_CODE ought to be RTX_CODE, but that's
 439      not necessarily defined at this point.  */
 440   bool (* rtx_costs) (rtx x, int code, int outer_code, int *total);
 441
 442   /* Compute the cost of X, used as an address.  Never called with
 443      invalid addresses.  */
 444   int (* address_cost) (rtx x);
 445
 446   /* Given a register, this hook should return a parallel of registers
 447      to represent where to find the register pieces.  Define this hook
 448      if the register and its mode are represented in Dwarf in
 449      non-contiguous locations, or if the register should be
 450      represented in more than one register in Dwarf.  Otherwise, this
 451      hook should return NULL_RTX.  */
 452   rtx (* dwarf_register_span) (rtx);
 453
 454   /* Fetch the fixed register(s) which hold condition codes, for
 455      targets where it makes sense to look for duplicate assignments to
 456      the condition codes.  This should return true if there is such a
 457      register, false otherwise.  The arguments should be set to the
 458      fixed register numbers.  Up to two condition code registers are
 459      supported.  If there is only one for this target, the int pointed
 460      at by the second argument should be set to -1.  */
 461   bool (* fixed_condition_code_regs) (unsigned int *, unsigned int *);
 462
 463   /* If two condition code modes are compatible, return a condition
 464      code mode which is compatible with both, such that a comparison
 465      done in the returned mode will work for both of the original
 466      modes.  If the condition code modes are not compatible, return
 467      VOIDmode.  */
 468   enum machine_mode (* cc_modes_compatible) (enum machine_mode,
 469                                              enum machine_mode);
 470
 471   /* Do machine-dependent code transformations.  Called just before
 472      delayed-branch scheduling.  */
 473   void (* machine_dependent_reorg) (void);
 474
 475   /* Create the __builtin_va_list type.  */
 476   tree (* build_builtin_va_list) (void);
 477
 478   /* Gimplifies a VA_ARG_EXPR.  */
 479   tree (* gimplify_va_arg_expr) (tree valist, tree type, tree *pre_p,
 480                                  tree *post_p);
 481
 482   /* Validity-checking routines for PCH files, target-specific.
 483      get_pch_validity returns a pointer to the data to be stored,
 484      and stores the size in its argument.  pch_valid_p gets the same
 485      information back and returns NULL if the PCH is valid,
 486      or an error message if not.
 487   */
 488   void * (* get_pch_validity) (size_t *);
 489   const char * (* pch_valid_p) (const void *, size_t);
 490
 491   /* If nonnull, this function checks whether a PCH file with the
 492      given set of target flags can be used.  It returns NULL if so,
 493      otherwise it returns an error message.  */
 494   const char *(*check_pch_target_flags) (int);
 495
 496   /* True if the compiler should give an enum type only as many
 497      bytes as it takes to represent the range of possible values of
 498      that type.  */
 499   bool (* default_short_enums) (void);
 500
 501   /* This target hook returns an rtx that is used to store the address
 502      of the current frame into the built-in setjmp buffer.  */
 503   rtx (* builtin_setjmp_frame_value) (void);
 504
 505   /* This target hook should add STRING_CST trees for any hard regs
 506      the port wishes to automatically clobber for an asm.  */
 507   tree (* md_asm_clobbers) (tree, tree, tree);
 508
 509   /* This target hook allows the backend to specify a calling convention
 510      in the debug information.  This function actually returns an
 511      enum dwarf_calling_convention, but because of forward declarations
 512      and not wanting to include dwarf2.h everywhere target.h is included
 513      the function is being declared as an int.  */
 514   int (* dwarf_calling_convention) (tree);
 515
 516   /* This target hook allows the backend to emit frame-related insns that
 517      contain UNSPECs or UNSPEC_VOLATILEs.  The call frame debugging info
 518      engine will invoke it on insns of the form
 519        (set (reg) (unspec [...] UNSPEC_INDEX))
 520      and
 521        (set (reg) (unspec_volatile [...] UNSPECV_INDEX))
 522      to let the backend emit the call frame instructions.  */
 523   void (* dwarf_handle_frame_unspec) (const char *, rtx, int);
 524
 525   /* Perform architecture specific checking of statements gimplified
 526      from VA_ARG_EXPR.  LHS is left hand side of MODIFY_EXPR, RHS
 527      is right hand side.  Returns true if the statements doesn't need
 528      to be checked for va_list references.  */
 529   bool (*stdarg_optimize_hook) (struct stdarg_info *ai, tree lhs, tree rhs);
 530
 531   /* Returns NULL if target supports the insn within a doloop block,
 532      otherwise it returns an error message.  */
 533   const char * (*invalid_within_doloop) (rtx);
 534
 535   /* Functions relating to calls - argument passing, returns, etc.  */
 536   struct calls {
 537     bool (*promote_function_args) (tree fntype);
 538     bool (*promote_function_return) (tree fntype);
 539     bool (*promote_prototypes) (tree fntype);
 540     rtx (*struct_value_rtx) (tree fndecl, int incoming);
 541     bool (*return_in_memory) (tree type, tree fndecl);
 542     bool (*return_in_msb) (tree type);
 543
 544     /* Return true if a parameter must be passed by reference.  TYPE may
 545        be null if this is a libcall.  CA may be null if this query is
 546        from __builtin_va_arg.  */
 547     bool (*pass_by_reference) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 548                                tree type, bool named_arg);
 549
 550     rtx (*expand_builtin_saveregs) (void);
 551     /* Returns pretend_argument_size.  */
 552     void (*setup_incoming_varargs) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 553                                     tree type, int *pretend_arg_size,
 554                                     int second_time);
 555     bool (*strict_argument_naming) (CUMULATIVE_ARGS *ca);
 556     /* Returns true if we should use
 557        targetm.calls.setup_incoming_varargs() and/or
 558        targetm.calls.strict_argument_naming().  */
 559     bool (*pretend_outgoing_varargs_named) (CUMULATIVE_ARGS *ca);
 560
 561     /* Given a complex type T, return true if a parameter of type T
 562        should be passed as two scalars.  */
 563     bool (* split_complex_arg) (tree type);
 564
 565     /* Return true if type T, mode MODE, may not be passed in registers,
 566        but must be passed on the stack.  */
 567     /* ??? This predicate should be applied strictly after pass-by-reference.
 568        Need audit to verify that this is the case.  */
 569     bool (* must_pass_in_stack) (enum machine_mode mode, tree t);
 570
 571     /* Return true if type TYPE, mode MODE, which is passed by reference,
 572        should have the object copy generated by the callee rather than
 573        the caller.  It is never called for TYPE requiring constructors.  */
 574     bool (* callee_copies) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 575                             tree type, bool named);
 576
 577     /* Return zero for arguments passed entirely on the stack or entirely
 578        in registers.  If passed in both, return the number of bytes passed
 579        in registers; the balance is therefore passed on the stack.  */
 580     int (* arg_partial_bytes) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 581                                tree type, bool named);
 582
 583     /* Return the diagnostic message string if function without a prototype
 584        is not allowed for this 'val' argument; NULL otherwise. */
 585     const char *(*invalid_arg_for_unprototyped_fn) (tree typelist,
 586                                                     tree funcdecl, tree val);
 587   } calls;
 588
 589   /* Functions specific to the C++ frontend.  */
 590   struct cxx {
 591     /* Return the integer type used for guard variables.  */
 592     tree (*guard_type) (void);
 593     /* Return true if only the low bit of the guard should be tested.  */
 594     bool (*guard_mask_bit) (void);
 595     /* Returns the size of the array cookie for an array of type.  */
 596     tree (*get_cookie_size) (tree);
 597     /* Returns true if the element size should be stored in the
 598        array cookie.  */
 599     bool (*cookie_has_size) (void);
 600     /* Allows backends to perform additional processing when
 601        deciding if a class should be exported or imported.  */
 602     int (*import_export_class) (tree, int);
 603     /* Returns true if constructors and destructors return "this".  */
 604     bool (*cdtor_returns_this) (void);
 605     /* Returns true if the key method for a class can be an inline
 606        function, so long as it is not declared inline in the class
 607        itself.  Returning true is the behavior required by the Itanium
 608        C++ ABI.  */
 609     bool (*key_method_may_be_inline) (void);
 610     /* DECL is a virtual table, virtual table table, typeinfo object,
 611        or other similar implicit class data object that will be
 612        emitted with external linkage in this translation unit.  No ELF
 613        visibility has been explicitly specified.  If the target needs
 614        to specify a visibility other than that of the containing class,
 615        use this hook to set DECL_VISIBILITY and
 616        DECL_VISIBILITY_SPECIFIED.  */
 617     void (*determine_class_data_visibility) (tree decl);
 618     /* Returns true (the default) if virtual tables and other
 619        similar implicit class data objects are always COMDAT if they
 620        have external linkage.  If this hook returns false, then
 621        class data for classes whose virtual table will be emitted in
 622        only one translation unit will not be COMDAT.  */
 623     bool (*class_data_always_comdat) (void);
 624     /* Returns true if __aeabi_atexit should be used to register static
 625        destructors.  */
 626     bool (*use_aeabi_atexit) (void);
 627   } cxx;
 628
 629   /* Leave the boolean fields at the end.  */
 630
 631   /* True if arbitrary sections are supported.  */
 632   bool have_named_sections;
 633
 634   /* True if "native" constructors and destructors are supported,
 635      false if we're using collect2 for the job.  */
 636   bool have_ctors_dtors;
 637
 638   /* True if thread-local storage is supported.  */
 639   bool have_tls;
 640
 641   /* True if a small readonly data section is supported.  */
 642   bool have_srodata_section;
 643
 644   /* True if EH frame info sections should be zero-terminated.  */
 645   bool terminate_dw2_eh_frame_info;
 646
 647   /* True if #NO_APP should be emitted at the beginning of
 648      assembly output.  */
 649   bool file_start_app_off;
 650
 651   /* True if output_file_directive should be called for main_input_filename
 652      at the beginning of assembly output.  */
 653   bool file_start_file_directive;
 654
 655   /* True if #pragma redefine_extname is to be supported.  */
 656   bool handle_pragma_redefine_extname;
 657
 658   /* True if #pragma extern_prefix is to be supported.  */
 659   bool handle_pragma_extern_prefix;
 660
 661   /* True if the target is allowed to reorder memory accesses unless
 662      synchronization is explicitly requested.  */
 663   bool relaxed_ordering;
 664
 665   /* Leave the boolean fields at the end.  */
 666 };
 667
 668 extern struct gcc_target targetm;
 669
 670 #endif /* GCC_TARGET_H */