gcc/target.h

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