gcc/target.h

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