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