old-autovect-branch/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 /* The struct used by the secondary_reload target hook.  */
  56 typedef struct secondary_reload_info
  57 {
  58   /* icode is actually an enum insn_code, but we don't want to force every
  59      file that includes target.h to include optabs.h .  */
  60   int icode;
  61   int extra_cost; /* Cost for using (a) scratch register(s) to be taken
  62                      into account by copy_cost.  */
  63   /* The next two members are for the use of the backward
  64      compatibility hook.  */
  65   struct secondary_reload_info *prev_sri;
  66   int t_icode; /* Actually an enum insn_code - see above.  */
  67 } secondary_reload_info;
  68
  69
  70 struct gcc_target
  71 {
  72   /* Functions that output assembler for the target.  */
  73   struct asm_out
  74   {
  75     /* Opening and closing parentheses for asm expression grouping.  */
  76     const char *open_paren, *close_paren;
  77
  78     /* Assembler instructions for creating various kinds of integer object.  */
  79     const char *byte_op;
  80     struct asm_int_op
  81     {
  82       const char *hi;
  83       const char *si;
  84       const char *di;
  85       const char *ti;
  86     } aligned_op, unaligned_op;
  87
  88     /* Try to output the assembler code for an integer object whose
  89        value is given by X.  SIZE is the size of the object in bytes and
  90        ALIGNED_P indicates whether it is aligned.  Return true if
  91        successful.  Only handles cases for which BYTE_OP, ALIGNED_OP
  92        and UNALIGNED_OP are NULL.  */
  93     bool (* integer) (rtx x, unsigned int size, int aligned_p);
  94
  95     /* Output code that will globalize a label.  */
  96     void (* globalize_label) (FILE *, const char *);
  97
  98     /* Output code that will emit a label for unwind info, if this
  99        target requires such labels.  Second argument is the decl the
 100        unwind info is associated with, third is a boolean: true if
 101        this is for exception handling, fourth is a boolean: true if
 102        this is only a placeholder for an omitted FDE.  */
 103     void (* unwind_label) (FILE *, tree, int, int);
 104
 105     /* Emit any directives required to unwind this instruction.  */
 106     void (* unwind_emit) (FILE *, rtx);
 107
 108     /* Output an internal label.  */
 109     void (* internal_label) (FILE *, const char *, unsigned long);
 110
 111     /* Emit a ttype table reference to a typeinfo object.  */
 112     bool (* ttype) (rtx);
 113
 114     /* Emit an assembler directive to set visibility for the symbol
 115        associated with the tree decl.  */
 116     void (* visibility) (tree, int);
 117
 118     /* Output the assembler code for entry to a function.  */
 119     void (* function_prologue) (FILE *, HOST_WIDE_INT);
 120
 121     /* Output the assembler code for end of prologue.  */
 122     void (* function_end_prologue) (FILE *);
 123
 124     /* Output the assembler code for start of epilogue.  */
 125     void (* function_begin_epilogue) (FILE *);
 126
 127     /* Output the assembler code for function exit.  */
 128     void (* function_epilogue) (FILE *, HOST_WIDE_INT);
 129
 130     /* Initialize target-specific sections.  */
 131     void (* init_sections) (void);
 132
 133     /* Tell assembler to change to section NAME with attributes FLAGS.
 134        If DECL is non-NULL, it is the VAR_DECL or FUNCTION_DECL with
 135        which this section is associated.  */
 136     void (* named_section) (const char *name, unsigned int flags, tree decl);
 137
 138     /* Return a section for EXP.  It may be a DECL or a constant.  RELOC
 139        is nonzero if runtime relocations must be applied; bit 1 will be
 140        set if the runtime relocations require non-local name resolution.
 141        ALIGN is the required alignment of the data.  */
 142     section *(* select_section) (tree, int, unsigned HOST_WIDE_INT);
 143
 144     /* Return a section for X.  MODE is X's mode and ALIGN is its
 145        alignment in bits.  */
 146     section *(* select_rtx_section) (enum machine_mode, rtx,
 147                                      unsigned HOST_WIDE_INT);
 148
 149     /* Select a unique section name for DECL.  RELOC is the same as
 150        for SELECT_SECTION.  */
 151     void (* unique_section) (tree, int);
 152
 153     /* Return the readonly data section associated with function DECL.  */
 154     section *(* function_rodata_section) (tree);
 155
 156     /* Output a constructor for a symbol with a given priority.  */
 157     void (* constructor) (rtx, int);
 158
 159     /* Output a destructor for a symbol with a given priority.  */
 160     void (* destructor) (rtx, int);
 161
 162     /* Output the assembler code for a thunk function.  THUNK_DECL is the
 163        declaration for the thunk function itself, FUNCTION is the decl for
 164        the target function.  DELTA is an immediate constant offset to be
 165        added to THIS.  If VCALL_OFFSET is nonzero, the word at
 166        *(*this + vcall_offset) should be added to THIS.  */
 167     void (* output_mi_thunk) (FILE *file, tree thunk_decl,
 168                               HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset,
 169                               tree function_decl);
 170
 171     /* Determine whether output_mi_thunk would succeed.  */
 172     /* ??? Ideally, this hook would not exist, and success or failure
 173        would be returned from output_mi_thunk directly.  But there's
 174        too much undo-able setup involved in invoking output_mi_thunk.
 175        Could be fixed by making output_mi_thunk emit rtl instead of
 176        text to the output file.  */
 177     bool (* can_output_mi_thunk) (tree thunk_decl, HOST_WIDE_INT delta,
 178                                   HOST_WIDE_INT vcall_offset,
 179                                   tree function_decl);
 180
 181     /* Output any boilerplate text needed at the beginning of a
 182        translation unit.  */
 183     void (*file_start) (void);
 184
 185     /* Output any boilerplate text needed at the end of a
 186        translation unit.  */
 187     void (*file_end) (void);
 188
 189     /* Output an assembler pseudo-op to declare a library function name
 190        external.  */
 191     void (*external_libcall) (rtx);
 192
 193      /* Output an assembler directive to mark decl live. This instructs
 194         linker to not dead code strip this symbol.  */
 195     void (*mark_decl_preserved) (const char *);
 196
 197     /* Output a DTP-relative reference to a TLS symbol.  */
 198     void (*output_dwarf_dtprel) (FILE *file, int size, rtx x);
 199
 200   } asm_out;
 201
 202   /* Functions relating to instruction scheduling.  */
 203   struct sched
 204   {
 205     /* Given the current cost, COST, of an insn, INSN, calculate and
 206        return a new cost based on its relationship to DEP_INSN through
 207        the dependence LINK.  The default is to make no adjustment.  */
 208     int (* adjust_cost) (rtx insn, rtx link, rtx def_insn, int cost);
 209
 210     /* Adjust the priority of an insn as you see fit.  Returns the new
 211        priority.  */
 212     int (* adjust_priority) (rtx, int);
 213
 214     /* Function which returns the maximum number of insns that can be
 215        scheduled in the same machine cycle.  This must be constant
 216        over an entire compilation.  The default is 1.  */
 217     int (* issue_rate) (void);
 218
 219     /* Calculate how much this insn affects how many more insns we
 220        can emit this cycle.  Default is they all cost the same.  */
 221     int (* variable_issue) (FILE *, int, rtx, int);
 222
 223     /* Initialize machine-dependent scheduling code.  */
 224     void (* md_init) (FILE *, int, int);
 225
 226     /* Finalize machine-dependent scheduling code.  */
 227     void (* md_finish) (FILE *, int);
 228
 229     /* Initialize machine-dependent function while scheduling code.  */
 230     void (* md_init_global) (FILE *, int, int);
 231
 232     /* Finalize machine-dependent function wide scheduling code.  */
 233     void (* md_finish_global) (FILE *, int);
 234
 235     /* Reorder insns in a machine-dependent fashion, in two different
 236        places.  Default does nothing.  */
 237     int (* reorder) (FILE *, int, rtx *, int *, int);
 238     int (* reorder2) (FILE *, int, rtx *, int *, int);
 239
 240     /* The following member value is a pointer to a function called
 241        after evaluation forward dependencies of insns in chain given
 242        by two parameter values (head and tail correspondingly).  */
 243     void (* dependencies_evaluation_hook) (rtx, rtx);
 244
 245     /* The values of the following four members are pointers to
 246        functions used to simplify the automaton descriptions.
 247        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 248        returning insns which are used to change the pipeline hazard
 249        recognizer state when the new simulated processor cycle
 250        correspondingly starts and finishes.  The function defined by
 251        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 252        to initialize the corresponding insns.  The default values of
 253        the members result in not changing the automaton state when
 254        the new simulated processor cycle correspondingly starts and
 255        finishes.  */
 256     void (* init_dfa_pre_cycle_insn) (void);
 257     rtx (* dfa_pre_cycle_insn) (void);
 258     void (* init_dfa_post_cycle_insn) (void);
 259     rtx (* dfa_post_cycle_insn) (void);
 260
 261     /* The following member value is a pointer to a function returning value
 262        which defines how many insns in queue `ready' will we try for
 263        multi-pass scheduling.  If the member value is nonzero and the
 264        function returns positive value, the DFA based scheduler will make
 265        multi-pass scheduling for the first cycle.  In other words, we will
 266        try to choose ready insn which permits to start maximum number of
 267        insns on the same cycle.  */
 268     int (* first_cycle_multipass_dfa_lookahead) (void);
 269
 270     /* The following member value is pointer to a function controlling
 271        what insns from the ready insn queue will be considered for the
 272        multipass insn scheduling.  If the hook returns zero for insn
 273        passed as the parameter, the insn will be not chosen to be
 274        issued.  */
 275     int (* first_cycle_multipass_dfa_lookahead_guard) (rtx);
 276
 277     /* The following member value is pointer to a function called by
 278        the insn scheduler before issuing insn passed as the third
 279        parameter on given cycle.  If the hook returns nonzero, the
 280        insn is not issued on given processors cycle.  Instead of that,
 281        the processor cycle is advanced.  If the value passed through
 282        the last parameter is zero, the insn ready queue is not sorted
 283        on the new cycle start as usually.  The first parameter passes
 284        file for debugging output.  The second one passes the scheduler
 285        verbose level of the debugging output.  The forth and the fifth
 286        parameter values are correspondingly processor cycle on which
 287        the previous insn has been issued and the current processor
 288        cycle.  */
 289     int (* dfa_new_cycle) (FILE *, int, rtx, int, int, int *);
 290
 291     /* The following member value is a pointer to a function called
 292        by the insn scheduler.  It should return true if there exists a
 293        dependence which is considered costly by the target, between
 294        the insn passed as the first parameter, and the insn passed as
 295        the second parameter.  The third parameter is the INSN_DEPEND
 296        link that represents the dependence between the two insns.  The
 297        fourth argument is the cost of the dependence as estimated by
 298        the scheduler.  The last argument is the distance in cycles
 299        between the already scheduled insn (first parameter) and the
 300        the second insn (second parameter).  */
 301     bool (* is_costly_dependence) (rtx, rtx, rtx, int, int);
 302   } sched;
 303
 304   /* Functions relating to vectorization.  */
 305   struct vectorize
 306   {
 307     /* The following member value is a pointer to a function called
 308        by the vectorizer, and returns the decl of the target builtin
 309        function.  */
 310     tree (* builtin_mask_for_load) (void);
 311
 312     tree (* builtin_mul_widen_even) (tree);
 313     tree (* builtin_mul_widen_odd) (tree);
 314
 315     tree (* builtin_extract_even) (tree, tree, tree, tree);
 316     tree (* builtin_extract_odd) (tree, tree, tree, tree);
 317   } vectorize;
 318
 319   /* The initial value of target_flags.  */
 320   int default_target_flags;
 321
 322   /* Handle target switch CODE (an OPT_* value).  ARG is the argument
 323      passed to the switch; it is NULL if no argument was.  VALUE is the
 324      value of ARG if CODE specifies a UInteger option, otherwise it is
 325      1 if the positive form of the switch was used and 0 if the negative
 326      form was.  Return true if the switch was valid.  */
 327   bool (* handle_option) (size_t code, const char *arg, int value);
 328
 329   /* Return machine mode for filter value.  */
 330   enum machine_mode (* eh_return_filter_mode) (void);
 331
 332   /* Given two decls, merge their attributes and return the result.  */
 333   tree (* merge_decl_attributes) (tree, tree);
 334
 335   /* Given two types, merge their attributes and return the result.  */
 336   tree (* merge_type_attributes) (tree, tree);
 337
 338   /* Table of machine attributes and functions to handle them.
 339      Ignored if NULL.  */
 340   const struct attribute_spec *attribute_table;
 341
 342   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 343      one if they are compatible and two if they are nearly compatible
 344      (which causes a warning to be generated).  */
 345   int (* comp_type_attributes) (tree type1, tree type2);
 346
 347   /* Assign default attributes to the newly defined TYPE.  */
 348   void (* set_default_type_attributes) (tree type);
 349
 350   /* Insert attributes on the newly created DECL.  */
 351   void (* insert_attributes) (tree decl, tree *attributes);
 352
 353   /* Return true if FNDECL (which has at least one machine attribute)
 354      can be inlined despite its machine attributes, false otherwise.  */
 355   bool (* function_attribute_inlinable_p) (tree fndecl);
 356
 357   /* Return true if bitfields in RECORD_TYPE should follow the
 358      Microsoft Visual C++ bitfield layout rules.  */
 359   bool (* ms_bitfield_layout_p) (tree record_type);
 360
 361   /* True if the target supports decimal floating point.  */
 362   bool (* decimal_float_supported_p) (void);
 363
 364   /* Return true if anonymous bitfields affect structure alignment.  */
 365   bool (* align_anon_bitfield) (void);
 366
 367   /* Set up target-specific built-in functions.  */
 368   void (* init_builtins) (void);
 369
 370   /* Expand a target-specific builtin.  */
 371   rtx (* expand_builtin) (tree exp, rtx target, rtx subtarget,
 372                           enum machine_mode mode, int ignore);
 373
 374   /* Select a replacement for a target-specific builtin.  This is done
 375      *before* regular type checking, and so allows the target to implement
 376      a crude form of function overloading.  The result is a complete
 377      expression that implements the operation.  */
 378   tree (*resolve_overloaded_builtin) (tree decl, tree params);
 379
 380   /* Fold a target-specific builtin.  */
 381   tree (* fold_builtin) (tree fndecl, tree arglist, bool ignore);
 382
 383   /* For a vendor-specific fundamental TYPE, return a pointer to
 384      a statically-allocated string containing the C++ mangling for
 385      TYPE.  In all other cases, return NULL.  */
 386   const char * (* mangle_fundamental_type) (tree type);
 387
 388   /* Make any adjustments to libfunc names needed for this target.  */
 389   void (* init_libfuncs) (void);
 390
 391   /* Given a decl, a section name, and whether the decl initializer
 392      has relocs, choose attributes for the section.  */
 393   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 394   unsigned int (* section_type_flags) (tree, const char *, int);
 395
 396   /* True if new jumps cannot be created, to replace existing ones or
 397      not, at the current point in the compilation.  */
 398   bool (* cannot_modify_jumps_p) (void);
 399
 400   /* Return a register class for which branch target register
 401      optimizations should be applied.  */
 402   int (* branch_target_register_class) (void);
 403
 404   /* Return true if branch target register optimizations should include
 405      callee-saved registers that are not already live during the current
 406      function.  AFTER_PE_GEN is true if prologues and epilogues have
 407      already been generated.  */
 408   bool (* branch_target_register_callee_saved) (bool after_pe_gen);
 409
 410   /* True if the constant X cannot be placed in the constant pool.  */
 411   bool (* cannot_force_const_mem) (rtx);
 412
 413   /* True if the insn X cannot be duplicated.  */
 414   bool (* cannot_copy_insn_p) (rtx);
 415
 416   /* True if X is considered to be commutative.  */
 417   bool (* commutative_p) (rtx, int);
 418
 419   /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS.  */
 420   rtx (* delegitimize_address) (rtx);
 421
 422   /* True if it is OK to do sibling call optimization for the specified
 423      call expression EXP.  DECL will be the called function, or NULL if
 424      this is an indirect call.  */
 425   bool (*function_ok_for_sibcall) (tree decl, tree exp);
 426
 427   /* True if EXP should be placed in a "small data" section.  */
 428   bool (* in_small_data_p) (tree);
 429
 430   /* True if EXP names an object for which name resolution must resolve
 431      to the current module.  */
 432   bool (* binds_local_p) (tree);
 433
 434   /* Do something target-specific to record properties of the DECL into
 435      the associated SYMBOL_REF.  */
 436   void (* encode_section_info) (tree, rtx, int);
 437
 438   /* Undo the effects of encode_section_info on the symbol string.  */
 439   const char * (* strip_name_encoding) (const char *);
 440
 441   /* If shift optabs for MODE are known to always truncate the shift count,
 442      return the mask that they apply.  Return 0 otherwise.  */
 443   unsigned HOST_WIDE_INT (* shift_truncation_mask) (enum machine_mode mode);
 444
 445   /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))).  */
 446   bool (* valid_pointer_mode) (enum machine_mode mode);
 447
 448   /* True if MODE is valid for the target.  By "valid", we mean able to
 449      be manipulated in non-trivial ways.  In particular, this means all
 450      the arithmetic is supported.  */
 451   bool (* scalar_mode_supported_p) (enum machine_mode mode);
 452
 453   /* Similarly for vector modes.  "Supported" here is less strict.  At
 454      least some operations are supported; need to check optabs or builtins
 455      for further details.  */
 456   bool (* vector_mode_supported_p) (enum machine_mode mode);
 457
 458   /* True if a vector is opaque.  */
 459   bool (* vector_opaque_p) (tree);
 460
 461   /* Compute a (partial) cost for rtx X.  Return true if the complete
 462      cost has been computed, and false if subexpressions should be
 463      scanned.  In either case, *TOTAL contains the cost result.  */
 464   /* Note that CODE and OUTER_CODE ought to be RTX_CODE, but that's
 465      not necessarily defined at this point.  */
 466   bool (* rtx_costs) (rtx x, int code, int outer_code, int *total);
 467
 468   /* Compute the cost of X, used as an address.  Never called with
 469      invalid addresses.  */
 470   int (* address_cost) (rtx x);
 471
 472   /* Return where to allocate pseudo for a given hard register initial
 473      value.  */
 474   rtx (* allocate_initial_value) (rtx x);
 475
 476   /* Given a register, this hook should return a parallel of registers
 477      to represent where to find the register pieces.  Define this hook
 478      if the register and its mode are represented in Dwarf in
 479      non-contiguous locations, or if the register should be
 480      represented in more than one register in Dwarf.  Otherwise, this
 481      hook should return NULL_RTX.  */
 482   rtx (* dwarf_register_span) (rtx);
 483
 484   /* Fetch the fixed register(s) which hold condition codes, for
 485      targets where it makes sense to look for duplicate assignments to
 486      the condition codes.  This should return true if there is such a
 487      register, false otherwise.  The arguments should be set to the
 488      fixed register numbers.  Up to two condition code registers are
 489      supported.  If there is only one for this target, the int pointed
 490      at by the second argument should be set to -1.  */
 491   bool (* fixed_condition_code_regs) (unsigned int *, unsigned int *);
 492
 493   /* If two condition code modes are compatible, return a condition
 494      code mode which is compatible with both, such that a comparison
 495      done in the returned mode will work for both of the original
 496      modes.  If the condition code modes are not compatible, return
 497      VOIDmode.  */
 498   enum machine_mode (* cc_modes_compatible) (enum machine_mode,
 499                                              enum machine_mode);
 500
 501   /* Do machine-dependent code transformations.  Called just before
 502      delayed-branch scheduling.  */
 503   void (* machine_dependent_reorg) (void);
 504
 505   /* Create the __builtin_va_list type.  */
 506   tree (* build_builtin_va_list) (void);
 507
 508   /* Gimplifies a VA_ARG_EXPR.  */
 509   tree (* gimplify_va_arg_expr) (tree valist, tree type, tree *pre_p,
 510                                  tree *post_p);
 511
 512   /* Validity-checking routines for PCH files, target-specific.
 513      get_pch_validity returns a pointer to the data to be stored,
 514      and stores the size in its argument.  pch_valid_p gets the same
 515      information back and returns NULL if the PCH is valid,
 516      or an error message if not.
 517   */
 518   void * (* get_pch_validity) (size_t *);
 519   const char * (* pch_valid_p) (const void *, size_t);
 520
 521   /* If nonnull, this function checks whether a PCH file with the
 522      given set of target flags can be used.  It returns NULL if so,
 523      otherwise it returns an error message.  */
 524   const char *(*check_pch_target_flags) (int);
 525
 526   /* True if the compiler should give an enum type only as many
 527      bytes as it takes to represent the range of possible values of
 528      that type.  */
 529   bool (* default_short_enums) (void);
 530
 531   /* This target hook returns an rtx that is used to store the address
 532      of the current frame into the built-in setjmp buffer.  */
 533   rtx (* builtin_setjmp_frame_value) (void);
 534
 535   /* This target hook should add STRING_CST trees for any hard regs
 536      the port wishes to automatically clobber for an asm.  */
 537   tree (* md_asm_clobbers) (tree, tree, tree);
 538
 539   /* This target hook allows the backend to specify a calling convention
 540      in the debug information.  This function actually returns an
 541      enum dwarf_calling_convention, but because of forward declarations
 542      and not wanting to include dwarf2.h everywhere target.h is included
 543      the function is being declared as an int.  */
 544   int (* dwarf_calling_convention) (tree);
 545
 546   /* This target hook allows the backend to emit frame-related insns that
 547      contain UNSPECs or UNSPEC_VOLATILEs.  The call frame debugging info
 548      engine will invoke it on insns of the form
 549        (set (reg) (unspec [...] UNSPEC_INDEX))
 550      and
 551        (set (reg) (unspec_volatile [...] UNSPECV_INDEX))
 552      to let the backend emit the call frame instructions.  */
 553   void (* dwarf_handle_frame_unspec) (const char *, rtx, int);
 554
 555   /* Perform architecture specific checking of statements gimplified
 556      from VA_ARG_EXPR.  LHS is left hand side of MODIFY_EXPR, RHS
 557      is right hand side.  Returns true if the statements doesn't need
 558      to be checked for va_list references.  */
 559   bool (* stdarg_optimize_hook) (struct stdarg_info *ai, tree lhs, tree rhs);
 560
 561   /* This target hook allows the operating system to override the DECL
 562      that represents the external variable that contains the stack
 563      protection guard variable.  The type of this DECL is ptr_type_node.  */
 564   tree (* stack_protect_guard) (void);
 565
 566   /* This target hook allows the operating system to override the CALL_EXPR
 567      that is invoked when a check vs the guard variable fails.  */
 568   tree (* stack_protect_fail) (void);
 569
 570   /* Returns NULL if target supports the insn within a doloop block,
 571      otherwise it returns an error message.  */
 572   const char * (*invalid_within_doloop) (rtx);
 573
 574   /* DECL is a variable or function with __attribute__((dllimport))
 575      specified.  Use this hook if the target needs to add extra validation
 576      checks to  handle_dll_attribute ().  */
 577   bool (* valid_dllimport_attribute_p) (tree decl);
 578
 579   /* Functions relating to calls - argument passing, returns, etc.  */
 580   struct calls {
 581     bool (*promote_function_args) (tree fntype);
 582     bool (*promote_function_return) (tree fntype);
 583     bool (*promote_prototypes) (tree fntype);
 584     rtx (*struct_value_rtx) (tree fndecl, int incoming);
 585     bool (*return_in_memory) (tree type, tree fndecl);
 586     bool (*return_in_msb) (tree type);
 587
 588     /* Return true if a parameter must be passed by reference.  TYPE may
 589        be null if this is a libcall.  CA may be null if this query is
 590        from __builtin_va_arg.  */
 591     bool (*pass_by_reference) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 592                                tree type, bool named_arg);
 593
 594     rtx (*expand_builtin_saveregs) (void);
 595     /* Returns pretend_argument_size.  */
 596     void (*setup_incoming_varargs) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 597                                     tree type, int *pretend_arg_size,
 598                                     int second_time);
 599     bool (*strict_argument_naming) (CUMULATIVE_ARGS *ca);
 600     /* Returns true if we should use
 601        targetm.calls.setup_incoming_varargs() and/or
 602        targetm.calls.strict_argument_naming().  */
 603     bool (*pretend_outgoing_varargs_named) (CUMULATIVE_ARGS *ca);
 604
 605     /* Given a complex type T, return true if a parameter of type T
 606        should be passed as two scalars.  */
 607     bool (* split_complex_arg) (tree type);
 608
 609     /* Return true if type T, mode MODE, may not be passed in registers,
 610        but must be passed on the stack.  */
 611     /* ??? This predicate should be applied strictly after pass-by-reference.
 612        Need audit to verify that this is the case.  */
 613     bool (* must_pass_in_stack) (enum machine_mode mode, tree t);
 614
 615     /* Return true if type TYPE, mode MODE, which is passed by reference,
 616        should have the object copy generated by the callee rather than
 617        the caller.  It is never called for TYPE requiring constructors.  */
 618     bool (* callee_copies) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 619                             tree type, bool named);
 620
 621     /* Return zero for arguments passed entirely on the stack or entirely
 622        in registers.  If passed in both, return the number of bytes passed
 623        in registers; the balance is therefore passed on the stack.  */
 624     int (* arg_partial_bytes) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 625                                tree type, bool named);
 626
 627     /* Return the diagnostic message string if function without a prototype
 628        is not allowed for this 'val' argument; NULL otherwise. */
 629     const char *(*invalid_arg_for_unprototyped_fn) (tree typelist,
 630                                                     tree funcdecl, tree val);
 631
 632     /* Return an rtx for the return value location of the function
 633        specified by FN_DECL_OR_TYPE with a return type of RET_TYPE.  */
 634     rtx (*function_value) (tree ret_type, tree fn_decl_or_type,
 635                            bool outgoing);
 636
 637     /* Return an rtx for the argument pointer incoming to the
 638        current function.  */
 639     rtx (*internal_arg_pointer) (void);
 640   } calls;
 641
 642   /* Return the diagnostic message string if conversion from FROMTYPE
 643      to TOTYPE is not allowed, NULL otherwise.  */
 644   const char *(*invalid_conversion) (tree fromtype, tree totype);
 645
 646   /* Return the diagnostic message string if the unary operation OP is
 647      not permitted on TYPE, NULL otherwise.  */
 648   const char *(*invalid_unary_op) (int op, tree type);
 649
 650   /* Return the diagnostic message string if the binary operation OP
 651      is not permitted on TYPE1 and TYPE2, NULL otherwise.  */
 652   const char *(*invalid_binary_op) (int op, tree type1, tree type2);
 653
 654   /* Return the class for a secondary reload, and fill in extra information.  */
 655   enum reg_class (*secondary_reload) (bool, rtx, enum reg_class,
 656                                       enum machine_mode,
 657                                       struct secondary_reload_info *);
 658
 659   /* Functions specific to the C++ frontend.  */
 660   struct cxx {
 661     /* Return the integer type used for guard variables.  */
 662     tree (*guard_type) (void);
 663     /* Return true if only the low bit of the guard should be tested.  */
 664     bool (*guard_mask_bit) (void);
 665     /* Returns the size of the array cookie for an array of type.  */
 666     tree (*get_cookie_size) (tree);
 667     /* Returns true if the element size should be stored in the
 668        array cookie.  */
 669     bool (*cookie_has_size) (void);
 670     /* Allows backends to perform additional processing when
 671        deciding if a class should be exported or imported.  */
 672     int (*import_export_class) (tree, int);
 673     /* Returns true if constructors and destructors return "this".  */
 674     bool (*cdtor_returns_this) (void);
 675     /* Returns true if the key method for a class can be an inline
 676        function, so long as it is not declared inline in the class
 677        itself.  Returning true is the behavior required by the Itanium
 678        C++ ABI.  */
 679     bool (*key_method_may_be_inline) (void);
 680     /* DECL is a virtual table, virtual table table, typeinfo object,
 681        or other similar implicit class data object that will be
 682        emitted with external linkage in this translation unit.  No ELF
 683        visibility has been explicitly specified.  If the target needs
 684        to specify a visibility other than that of the containing class,
 685        use this hook to set DECL_VISIBILITY and
 686        DECL_VISIBILITY_SPECIFIED.  */
 687     void (*determine_class_data_visibility) (tree decl);
 688     /* Returns true (the default) if virtual tables and other
 689        similar implicit class data objects are always COMDAT if they
 690        have external linkage.  If this hook returns false, then
 691        class data for classes whose virtual table will be emitted in
 692        only one translation unit will not be COMDAT.  */
 693     bool (*class_data_always_comdat) (void);
 694     /* Returns true if __aeabi_atexit should be used to register static
 695        destructors.  */
 696     bool (*use_aeabi_atexit) (void);
 697     /* TYPE is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that
 698        has just been defined.  Use this hook to make adjustments to the
 699        class  (eg, tweak visibility or perform any other required
 700        target modifications).  */
 701     void (*adjust_class_at_definition) (tree type);
 702   } cxx;
 703
 704   /* True if unwinding tables should be generated by default.  */
 705   bool unwind_tables_default;
 706
 707   /* Leave the boolean fields at the end.  */
 708
 709   /* True if arbitrary sections are supported.  */
 710   bool have_named_sections;
 711
 712   /* True if "native" constructors and destructors are supported,
 713      false if we're using collect2 for the job.  */
 714   bool have_ctors_dtors;
 715
 716   /* True if thread-local storage is supported.  */
 717   bool have_tls;
 718
 719   /* True if a small readonly data section is supported.  */
 720   bool have_srodata_section;
 721
 722   /* True if EH frame info sections should be zero-terminated.  */
 723   bool terminate_dw2_eh_frame_info;
 724
 725   /* True if #NO_APP should be emitted at the beginning of
 726      assembly output.  */
 727   bool file_start_app_off;
 728
 729   /* True if output_file_directive should be called for main_input_filename
 730      at the beginning of assembly output.  */
 731   bool file_start_file_directive;
 732
 733   /* True if #pragma redefine_extname is to be supported.  */
 734   bool handle_pragma_redefine_extname;
 735
 736   /* True if #pragma extern_prefix is to be supported.  */
 737   bool handle_pragma_extern_prefix;
 738
 739   /* True if the target is allowed to reorder memory accesses unless
 740      synchronization is explicitly requested.  */
 741   bool relaxed_ordering;
 742
 743   /* Returns true if we should generate exception tables for use with the
 744      ARM EABI.  The effects the encoding of function exception specifications.
 745    */
 746   bool arm_eabi_unwinder;
 747
 748   /* Leave the boolean fields at the end.  */
 749 };
 750
 751 extern struct gcc_target targetm;
 752
 753 #endif /* GCC_TARGET_H */