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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 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 a ttype table reference to a typeinfo object.  */
  97     bool (* ttype) (rtx);
  98
  99     /* Emit an assembler directive to set visibility for the symbol
 100        associated with the tree decl.  */
 101     void (* visibility) (tree, int);
 102
 103     /* Output the assembler code for entry to a function.  */
 104     void (* function_prologue) (FILE *, HOST_WIDE_INT);
 105
 106     /* Output the assembler code for end of prologue.  */
 107     void (* function_end_prologue) (FILE *);
 108
 109     /* Output the assembler code for start of epilogue.  */
 110     void (* function_begin_epilogue) (FILE *);
 111
 112     /* Output the assembler code for function exit.  */
 113     void (* function_epilogue) (FILE *, HOST_WIDE_INT);
 114
 115     /* Tell assembler to change to section NAME with attributes FLAGS.
 116        If DECL is non-NULL, it is the VAR_DECL or FUNCTION_DECL with
 117        which this section is associated.  */
 118     void (* named_section) (const char *name, unsigned int flags, tree decl);
 119
 120     /* Switch to the section that holds the exception table.  */
 121     void (* exception_section) (void);
 122
 123     /* Switch to the section that holds the exception frames.  */
 124     void (* eh_frame_section) (void);
 125
 126     /* Select and switch to a section for EXP.  It may be a DECL or a
 127        constant.  RELOC is nonzero if runtime relocations must be applied;
 128        bit 1 will be set if the runtime relocations require non-local
 129        name resolution.  ALIGN is the required alignment of the data.  */
 130     void (* select_section) (tree, int, unsigned HOST_WIDE_INT);
 131
 132     /* Select and switch to a section for X with MODE.  ALIGN is
 133        the desired alignment of the data.  */
 134     void (* select_rtx_section) (enum machine_mode, rtx,
 135                                  unsigned HOST_WIDE_INT);
 136
 137     /* Select a unique section name for DECL.  RELOC is the same as
 138        for SELECT_SECTION.  */
 139     void (* unique_section) (tree, int);
 140
 141     /* Tell assembler to switch to the readonly data section associated
 142        with function DECL.  */
 143     void (* function_rodata_section) (tree);
 144
 145     /* Output a constructor for a symbol with a given priority.  */
 146     void (* constructor) (rtx, int);
 147
 148     /* Output a destructor for a symbol with a given priority.  */
 149     void (* destructor) (rtx, int);
 150
 151     /* Output the assembler code for a thunk function.  THUNK_DECL is the
 152        declaration for the thunk function itself, FUNCTION is the decl for
 153        the target function.  DELTA is an immediate constant offset to be
 154        added to THIS.  If VCALL_OFFSET is nonzero, the word at
 155        *(*this + vcall_offset) should be added to THIS.  */
 156     void (* output_mi_thunk) (FILE *file, tree thunk_decl,
 157                               HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset,
 158                               tree function_decl);
 159
 160     /* Determine whether output_mi_thunk would succeed.  */
 161     /* ??? Ideally, this hook would not exist, and success or failure
 162        would be returned from output_mi_thunk directly.  But there's
 163        too much undo-able setup involved in invoking output_mi_thunk.
 164        Could be fixed by making output_mi_thunk emit rtl instead of
 165        text to the output file.  */
 166     bool (* can_output_mi_thunk) (tree thunk_decl, HOST_WIDE_INT delta,
 167                                   HOST_WIDE_INT vcall_offset,
 168                                   tree function_decl);
 169
 170     /* Output any boilerplate text needed at the beginning of a
 171        translation unit.  */
 172     void (*file_start) (void);
 173
 174     /* Output any boilerplate text needed at the end of a
 175        translation unit.  */
 176     void (*file_end) (void);
 177
 178     /* Output an assembler pseudo-op to declare a library function name
 179        external.  */
 180     void (*external_libcall) (rtx);
 181
 182      /* Output an assembler directive to mark decl live. This instructs
 183         linker to not dead code strip this symbol.  */
 184     void (*mark_decl_preserved) (const char *);
 185
 186     /* Output a DTP-relative reference to a TLS symbol.  */
 187     void (*output_dwarf_dtprel) (FILE *file, int size, rtx x);
 188
 189   } asm_out;
 190
 191   /* Functions relating to instruction scheduling.  */
 192   struct sched
 193   {
 194     /* Given the current cost, COST, of an insn, INSN, calculate and
 195        return a new cost based on its relationship to DEP_INSN through
 196        the dependence LINK.  The default is to make no adjustment.  */
 197     int (* adjust_cost) (rtx insn, rtx link, rtx def_insn, int cost);
 198
 199     /* Adjust the priority of an insn as you see fit.  Returns the new
 200        priority.  */
 201     int (* adjust_priority) (rtx, int);
 202
 203     /* Function which returns the maximum number of insns that can be
 204        scheduled in the same machine cycle.  This must be constant
 205        over an entire compilation.  The default is 1.  */
 206     int (* issue_rate) (void);
 207
 208     /* Calculate how much this insn affects how many more insns we
 209        can emit this cycle.  Default is they all cost the same.  */
 210     int (* variable_issue) (FILE *, int, rtx, int);
 211
 212     /* Initialize machine-dependent scheduling code.  */
 213     void (* md_init) (FILE *, int, int);
 214
 215     /* Finalize machine-dependent scheduling code.  */
 216     void (* md_finish) (FILE *, int);
 217
 218     /* Initialize machine-dependent function while scheduling code.  */
 219     void (* md_init_global) (FILE *, int, int);
 220
 221     /* Finalize machine-dependent function wide scheduling code.  */
 222     void (* md_finish_global) (FILE *, int);
 223
 224     /* Reorder insns in a machine-dependent fashion, in two different
 225        places.  Default does nothing.  */
 226     int (* reorder) (FILE *, int, rtx *, int *, int);
 227     int (* reorder2) (FILE *, int, rtx *, int *, int);
 228
 229     /* The following member value is a pointer to a function called
 230        after evaluation forward dependencies of insns in chain given
 231        by two parameter values (head and tail correspondingly).  */
 232     void (* dependencies_evaluation_hook) (rtx, rtx);
 233
 234     /* The values of the following four members are pointers to
 235        functions used to simplify the automaton descriptions.
 236        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 237        returning insns which are used to change the pipeline hazard
 238        recognizer state when the new simulated processor cycle
 239        correspondingly starts and finishes.  The function defined by
 240        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 241        to initialize the corresponding insns.  The default values of
 242        the members result in not changing the automaton state when
 243        the new simulated processor cycle correspondingly starts and
 244        finishes.  */
 245     void (* init_dfa_pre_cycle_insn) (void);
 246     rtx (* dfa_pre_cycle_insn) (void);
 247     void (* init_dfa_post_cycle_insn) (void);
 248     rtx (* dfa_post_cycle_insn) (void);
 249
 250     /* The following member value is a pointer to a function returning value
 251        which defines how many insns in queue `ready' will we try for
 252        multi-pass scheduling.  If the member value is nonzero and the
 253        function returns positive value, the DFA based scheduler will make
 254        multi-pass scheduling for the first cycle.  In other words, we will
 255        try to choose ready insn which permits to start maximum number of
 256        insns on the same cycle.  */
 257     int (* first_cycle_multipass_dfa_lookahead) (void);
 258
 259     /* The following member value is pointer to a function controlling
 260        what insns from the ready insn queue will be considered for the
 261        multipass insn scheduling.  If the hook returns zero for insn
 262        passed as the parameter, the insn will be not chosen to be
 263        issued.  */
 264     int (* first_cycle_multipass_dfa_lookahead_guard) (rtx);
 265
 266     /* The following member value is pointer to a function called by
 267        the insn scheduler before issuing insn passed as the third
 268        parameter on given cycle.  If the hook returns nonzero, the
 269        insn is not issued on given processors cycle.  Instead of that,
 270        the processor cycle is advanced.  If the value passed through
 271        the last parameter is zero, the insn ready queue is not sorted
 272        on the new cycle start as usually.  The first parameter passes
 273        file for debugging output.  The second one passes the scheduler
 274        verbose level of the debugging output.  The forth and the fifth
 275        parameter values are correspondingly processor cycle on which
 276        the previous insn has been issued and the current processor
 277        cycle.  */
 278     int (* dfa_new_cycle) (FILE *, int, rtx, int, int, int *);
 279
 280     /* The following member value is a pointer to a function called
 281        by the insn scheduler.  It should return true if there exists a
 282        dependence which is considered costly by the target, between
 283        the insn passed as the first parameter, and the insn passed as
 284        the second parameter.  The third parameter is the INSN_DEPEND
 285        link that represents the dependence between the two insns.  The
 286        fourth argument is the cost of the dependence as estimated by
 287        the scheduler.  The last argument is the distance in cycles
 288        between the already scheduled insn (first parameter) and the
 289        the second insn (second parameter).  */
 290     bool (* is_costly_dependence) (rtx, rtx, rtx, int, int);
 291   } sched;
 292
 293   /* Functions relating to vectorization.  */
 294   struct vectorize
 295   {
 296     /* The following member value is a pointer to a function called
 297        by the vectorizer, and return the decl of the target builtin
 298        function.  */
 299     tree (* builtin_mask_for_load) (void);
 300   } vectorize;
 301
 302   /* The initial value of target_flags.  */
 303   int default_target_flags;
 304
 305   /* Handle target switch CODE (an OPT_* value).  ARG is the argument
 306      passed to the switch; it is NULL if no argument was.  VALUE is the
 307      value of ARG if CODE specifies a UInteger option, otherwise it is
 308      1 if the positive form of the switch was used and 0 if the negative
 309      form was.  Return true if the switch was valid.  */
 310   bool (* handle_option) (size_t code, const char *arg, int value);
 311
 312   /* Return machine mode for filter value.  */
 313   enum machine_mode (* eh_return_filter_mode) (void);
 314
 315   /* Given two decls, merge their attributes and return the result.  */
 316   tree (* merge_decl_attributes) (tree, tree);
 317
 318   /* Given two types, merge their attributes and return the result.  */
 319   tree (* merge_type_attributes) (tree, tree);
 320
 321   /* Table of machine attributes and functions to handle them.
 322      Ignored if NULL.  */
 323   const struct attribute_spec *attribute_table;
 324
 325   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 326      one if they are compatible and two if they are nearly compatible
 327      (which causes a warning to be generated).  */
 328   int (* comp_type_attributes) (tree type1, tree type2);
 329
 330   /* Assign default attributes to the newly defined TYPE.  */
 331   void (* set_default_type_attributes) (tree type);
 332
 333   /* Insert attributes on the newly created DECL.  */
 334   void (* insert_attributes) (tree decl, tree *attributes);
 335
 336   /* Return true if FNDECL (which has at least one machine attribute)
 337      can be inlined despite its machine attributes, false otherwise.  */
 338   bool (* function_attribute_inlinable_p) (tree fndecl);
 339
 340   /* Return true if bitfields in RECORD_TYPE should follow the
 341      Microsoft Visual C++ bitfield layout rules.  */
 342   bool (* ms_bitfield_layout_p) (tree record_type);
 343
 344   /* Return true if anonymous bitfields affect structure alignment.  */
 345   bool (* align_anon_bitfield) (void);
 346
 347   /* Set up target-specific built-in functions.  */
 348   void (* init_builtins) (void);
 349
 350   /* Expand a target-specific builtin.  */
 351   rtx (* expand_builtin) (tree exp, rtx target, rtx subtarget,
 352                           enum machine_mode mode, int ignore);
 353
 354   /* Select a replacement for a target-specific builtin.  This is done
 355      *before* regular type checking, and so allows the target to implement
 356      a crude form of function overloading.  The result is a complete
 357      expression that implements the operation.  */
 358   tree (*resolve_overloaded_builtin) (tree decl, tree params);
 359
 360   /* Fold a target-specific builtin.  */
 361   tree (* fold_builtin) (tree fndecl, tree arglist, bool ignore);
 362
 363   /* For a vendor-specific fundamental TYPE, return a pointer to
 364      a statically-allocated string containing the C++ mangling for
 365      TYPE.  In all other cases, return NULL.  */
 366   const char * (* mangle_fundamental_type) (tree type);
 367
 368   /* Make any adjustments to libfunc names needed for this target.  */
 369   void (* init_libfuncs) (void);
 370
 371   /* Given a decl, a section name, and whether the decl initializer
 372      has relocs, choose attributes for the section.  */
 373   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 374   unsigned int (* section_type_flags) (tree, const char *, int);
 375
 376   /* True if new jumps cannot be created, to replace existing ones or
 377      not, at the current point in the compilation.  */
 378   bool (* cannot_modify_jumps_p) (void);
 379
 380   /* Return a register class for which branch target register
 381      optimizations should be applied.  */
 382   int (* branch_target_register_class) (void);
 383
 384   /* Return true if branch target register optimizations should include
 385      callee-saved registers that are not already live during the current
 386      function.  AFTER_PE_GEN is true if prologues and epilogues have
 387      already been generated.  */
 388   bool (* branch_target_register_callee_saved) (bool after_pe_gen);
 389
 390   /* True if the constant X cannot be placed in the constant pool.  */
 391   bool (* cannot_force_const_mem) (rtx);
 392
 393   /* True if the insn X cannot be duplicated.  */
 394   bool (* cannot_copy_insn_p) (rtx);
 395
 396   /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS.  */
 397   rtx (* delegitimize_address) (rtx);
 398
 399   /* True if it is OK to do sibling call optimization for the specified
 400      call expression EXP.  DECL will be the called function, or NULL if
 401      this is an indirect call.  */
 402   bool (*function_ok_for_sibcall) (tree decl, tree exp);
 403
 404   /* True if EXP should be placed in a "small data" section.  */
 405   bool (* in_small_data_p) (tree);
 406
 407   /* True if EXP names an object for which name resolution must resolve
 408      to the current module.  */
 409   bool (* binds_local_p) (tree);
 410
 411   /* Do something target-specific to record properties of the DECL into
 412      the associated SYMBOL_REF.  */
 413   void (* encode_section_info) (tree, rtx, int);
 414
 415   /* Undo the effects of encode_section_info on the symbol string.  */
 416   const char * (* strip_name_encoding) (const char *);
 417
 418   /* If shift optabs for MODE are known to always truncate the shift count,
 419      return the mask that they apply.  Return 0 otherwise.  */
 420   unsigned HOST_WIDE_INT (* shift_truncation_mask) (enum machine_mode mode);
 421
 422   /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))).  */
 423   bool (* valid_pointer_mode) (enum machine_mode mode);
 424
 425   /* True if MODE is valid for the target.  By "valid", we mean able to
 426      be manipulated in non-trivial ways.  In particular, this means all
 427      the arithmetic is supported.  */
 428   bool (* scalar_mode_supported_p) (enum machine_mode mode);
 429
 430   /* Similarly for vector modes.  "Supported" here is less strict.  At
 431      least some operations are supported; need to check optabs or builtins
 432      for further details.  */
 433   bool (* vector_mode_supported_p) (enum machine_mode mode);
 434
 435   /* True if a vector is opaque.  */
 436   bool (* vector_opaque_p) (tree);
 437
 438   /* Compute a (partial) cost for rtx X.  Return true if the complete
 439      cost has been computed, and false if subexpressions should be
 440      scanned.  In either case, *TOTAL contains the cost result.  */
 441   /* Note that CODE and OUTER_CODE ought to be RTX_CODE, but that's
 442      not necessarily defined at this point.  */
 443   bool (* rtx_costs) (rtx x, int code, int outer_code, int *total);
 444
 445   /* Compute the cost of X, used as an address.  Never called with
 446      invalid addresses.  */
 447   int (* address_cost) (rtx x);
 448
 449   /* Given a register, this hook should return a parallel of registers
 450      to represent where to find the register pieces.  Define this hook
 451      if the register and its mode are represented in Dwarf in
 452      non-contiguous locations, or if the register should be
 453      represented in more than one register in Dwarf.  Otherwise, this
 454      hook should return NULL_RTX.  */
 455   rtx (* dwarf_register_span) (rtx);
 456
 457   /* Fetch the fixed register(s) which hold condition codes, for
 458      targets where it makes sense to look for duplicate assignments to
 459      the condition codes.  This should return true if there is such a
 460      register, false otherwise.  The arguments should be set to the
 461      fixed register numbers.  Up to two condition code registers are
 462      supported.  If there is only one for this target, the int pointed
 463      at by the second argument should be set to -1.  */
 464   bool (* fixed_condition_code_regs) (unsigned int *, unsigned int *);
 465
 466   /* If two condition code modes are compatible, return a condition
 467      code mode which is compatible with both, such that a comparison
 468      done in the returned mode will work for both of the original
 469      modes.  If the condition code modes are not compatible, return
 470      VOIDmode.  */
 471   enum machine_mode (* cc_modes_compatible) (enum machine_mode,
 472                                              enum machine_mode);
 473
 474   /* Do machine-dependent code transformations.  Called just before
 475      delayed-branch scheduling.  */
 476   void (* machine_dependent_reorg) (void);
 477
 478   /* Create the __builtin_va_list type.  */
 479   tree (* build_builtin_va_list) (void);
 480
 481   /* Gimplifies a VA_ARG_EXPR.  */
 482   tree (* gimplify_va_arg_expr) (tree valist, tree type, tree *pre_p,
 483                                  tree *post_p);
 484
 485   /* Validity-checking routines for PCH files, target-specific.
 486      get_pch_validity returns a pointer to the data to be stored,
 487      and stores the size in its argument.  pch_valid_p gets the same
 488      information back and returns NULL if the PCH is valid,
 489      or an error message if not.
 490   */
 491   void * (* get_pch_validity) (size_t *);
 492   const char * (* pch_valid_p) (const void *, size_t);
 493
 494   /* If nonnull, this function checks whether a PCH file with the
 495      given set of target flags can be used.  It returns NULL if so,
 496      otherwise it returns an error message.  */
 497   const char *(*check_pch_target_flags) (int);
 498
 499   /* True if the compiler should give an enum type only as many
 500      bytes as it takes to represent the range of possible values of
 501      that type.  */
 502   bool (* default_short_enums) (void);
 503
 504   /* This target hook returns an rtx that is used to store the address
 505      of the current frame into the built-in setjmp buffer.  */
 506   rtx (* builtin_setjmp_frame_value) (void);
 507
 508   /* This target hook should add STRING_CST trees for any hard regs
 509      the port wishes to automatically clobber for an asm.  */
 510   tree (* md_asm_clobbers) (tree, tree, tree);
 511
 512   /* This target hook allows the backend to specify a calling convention
 513      in the debug information.  This function actually returns an
 514      enum dwarf_calling_convention, but because of forward declarations
 515      and not wanting to include dwarf2.h everywhere target.h is included
 516      the function is being declared as an int.  */
 517   int (* dwarf_calling_convention) (tree);
 518
 519   /* This target hook allows the backend to emit frame-related insns that
 520      contain UNSPECs or UNSPEC_VOLATILEs.  The call frame debugging info
 521      engine will invoke it on insns of the form
 522        (set (reg) (unspec [...] UNSPEC_INDEX))
 523      and
 524        (set (reg) (unspec_volatile [...] UNSPECV_INDEX))
 525      to let the backend emit the call frame instructions.  */
 526   void (* dwarf_handle_frame_unspec) (const char *, rtx, int);
 527
 528   /* Perform architecture specific checking of statements gimplified
 529      from VA_ARG_EXPR.  LHS is left hand side of MODIFY_EXPR, RHS
 530      is right hand side.  Returns true if the statements doesn't need
 531      to be checked for va_list references.  */
 532   bool (* stdarg_optimize_hook) (struct stdarg_info *ai, tree lhs, tree rhs);
 533
 534   /* This target hook allows the operating system to override the DECL
 535      that represents the external variable that contains the stack
 536      protection guard variable.  The type of this DECL is ptr_type_node.  */
 537   tree (* stack_protect_guard) (void);
 538
 539   /* This target hook allows the operating system to override the CALL_EXPR
 540      that is invoked when a check vs the guard variable fails.  */
 541   tree (* stack_protect_fail) (void);
 542
 543   /* Returns NULL if target supports the insn within a doloop block,
 544      otherwise it returns an error message.  */
 545   const char * (*invalid_within_doloop) (rtx);
 546
 547   /* Functions relating to calls - argument passing, returns, etc.  */
 548   struct calls {
 549     bool (*promote_function_args) (tree fntype);
 550     bool (*promote_function_return) (tree fntype);
 551     bool (*promote_prototypes) (tree fntype);
 552     rtx (*struct_value_rtx) (tree fndecl, int incoming);
 553     bool (*return_in_memory) (tree type, tree fndecl);
 554     bool (*return_in_msb) (tree type);
 555
 556     /* Return true if a parameter must be passed by reference.  TYPE may
 557        be null if this is a libcall.  CA may be null if this query is
 558        from __builtin_va_arg.  */
 559     bool (*pass_by_reference) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 560                                tree type, bool named_arg);
 561
 562     rtx (*expand_builtin_saveregs) (void);
 563     /* Returns pretend_argument_size.  */
 564     void (*setup_incoming_varargs) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 565                                     tree type, int *pretend_arg_size,
 566                                     int second_time);
 567     bool (*strict_argument_naming) (CUMULATIVE_ARGS *ca);
 568     /* Returns true if we should use
 569        targetm.calls.setup_incoming_varargs() and/or
 570        targetm.calls.strict_argument_naming().  */
 571     bool (*pretend_outgoing_varargs_named) (CUMULATIVE_ARGS *ca);
 572
 573     /* Given a complex type T, return true if a parameter of type T
 574        should be passed as two scalars.  */
 575     bool (* split_complex_arg) (tree type);
 576
 577     /* Return true if type T, mode MODE, may not be passed in registers,
 578        but must be passed on the stack.  */
 579     /* ??? This predicate should be applied strictly after pass-by-reference.
 580        Need audit to verify that this is the case.  */
 581     bool (* must_pass_in_stack) (enum machine_mode mode, tree t);
 582
 583     /* Return true if type TYPE, mode MODE, which is passed by reference,
 584        should have the object copy generated by the callee rather than
 585        the caller.  It is never called for TYPE requiring constructors.  */
 586     bool (* callee_copies) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 587                             tree type, bool named);
 588
 589     /* Return zero for arguments passed entirely on the stack or entirely
 590        in registers.  If passed in both, return the number of bytes passed
 591        in registers; the balance is therefore passed on the stack.  */
 592     int (* arg_partial_bytes) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 593                                tree type, bool named);
 594
 595     /* Return the diagnostic message string if function without a prototype
 596        is not allowed for this 'val' argument; NULL otherwise. */
 597     const char *(*invalid_arg_for_unprototyped_fn) (tree typelist,
 598                                                     tree funcdecl, tree val);
 599   } calls;
 600
 601   /* Functions specific to the C++ frontend.  */
 602   struct cxx {
 603     /* Return the integer type used for guard variables.  */
 604     tree (*guard_type) (void);
 605     /* Return true if only the low bit of the guard should be tested.  */
 606     bool (*guard_mask_bit) (void);
 607     /* Returns the size of the array cookie for an array of type.  */
 608     tree (*get_cookie_size) (tree);
 609     /* Returns true if the element size should be stored in the
 610        array cookie.  */
 611     bool (*cookie_has_size) (void);
 612     /* Allows backends to perform additional processing when
 613        deciding if a class should be exported or imported.  */
 614     int (*import_export_class) (tree, int);
 615     /* Returns true if constructors and destructors return "this".  */
 616     bool (*cdtor_returns_this) (void);
 617     /* Returns true if the key method for a class can be an inline
 618        function, so long as it is not declared inline in the class
 619        itself.  Returning true is the behavior required by the Itanium
 620        C++ ABI.  */
 621     bool (*key_method_may_be_inline) (void);
 622     /* DECL is a virtual table, virtual table table, typeinfo object,
 623        or other similar implicit class data object that will be
 624        emitted with external linkage in this translation unit.  No ELF
 625        visibility has been explicitly specified.  If the target needs
 626        to specify a visibility other than that of the containing class,
 627        use this hook to set DECL_VISIBILITY and
 628        DECL_VISIBILITY_SPECIFIED.  */
 629     void (*determine_class_data_visibility) (tree decl);
 630     /* Returns true (the default) if virtual tables and other
 631        similar implicit class data objects are always COMDAT if they
 632        have external linkage.  If this hook returns false, then
 633        class data for classes whose virtual table will be emitted in
 634        only one translation unit will not be COMDAT.  */
 635     bool (*class_data_always_comdat) (void);
 636     /* Returns true if __aeabi_atexit should be used to register static
 637        destructors.  */
 638     bool (*use_aeabi_atexit) (void);
 639   } cxx;
 640
 641   /* True if unwinding tables should be generated by default.  */
 642   bool unwind_tables_default;
 643
 644   /* Leave the boolean fields at the end.  */
 645
 646   /* True if arbitrary sections are supported.  */
 647   bool have_named_sections;
 648
 649   /* True if "native" constructors and destructors are supported,
 650      false if we're using collect2 for the job.  */
 651   bool have_ctors_dtors;
 652
 653   /* True if thread-local storage is supported.  */
 654   bool have_tls;
 655
 656   /* True if a small readonly data section is supported.  */
 657   bool have_srodata_section;
 658
 659   /* True if EH frame info sections should be zero-terminated.  */
 660   bool terminate_dw2_eh_frame_info;
 661
 662   /* True if #NO_APP should be emitted at the beginning of
 663      assembly output.  */
 664   bool file_start_app_off;
 665
 666   /* True if output_file_directive should be called for main_input_filename
 667      at the beginning of assembly output.  */
 668   bool file_start_file_directive;
 669
 670   /* True if #pragma redefine_extname is to be supported.  */
 671   bool handle_pragma_redefine_extname;
 672
 673   /* True if #pragma extern_prefix is to be supported.  */
 674   bool handle_pragma_extern_prefix;
 675
 676   /* True if the target is allowed to reorder memory accesses unless
 677      synchronization is explicitly requested.  */
 678   bool relaxed_ordering;
 679
 680   /* Returns true if we should generate exception tables for use with the
 681      ARM EABI.  The effects the encoding of function exception specifications.
 682    */
 683   bool arm_eabi_unwinder;
 684
 685   /* Leave the boolean fields at the end.  */
 686 };
 687
 688 extern struct gcc_target targetm;
 689
 690 #endif /* GCC_TARGET_H */