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     /* Output an internal label.  */
  89     void (* internal_label) (FILE *, const char *, unsigned long);
  90
  91     /* Emit an assembler directive to set visibility for the symbol
  92        associated with the tree decl.  */
  93     void (* visibility) (tree, int);
  94
  95     /* Output the assembler code for entry to a function.  */
  96     void (* function_prologue) (FILE *, HOST_WIDE_INT);
  97
  98     /* Output the assembler code for end of prologue.  */
  99     void (* function_end_prologue) (FILE *);
 100
 101     /* Output the assembler code for start of epilogue.  */
 102     void (* function_begin_epilogue) (FILE *);
 103
 104     /* Output the assembler code for function exit.  */
 105     void (* function_epilogue) (FILE *, HOST_WIDE_INT);
 106
 107     /* Switch to an arbitrary section NAME with attributes as
 108        specified by FLAGS.  */
 109     void (* named_section) (const char *, unsigned int);
 110
 111     /* Switch to the section that holds the exception table.  */
 112     void (* exception_section) (void);
 113
 114     /* Switch to the section that holds the exception frames.  */
 115     void (* eh_frame_section) (void);
 116
 117     /* Select and switch to a section for EXP.  It may be a DECL or a
 118        constant.  RELOC is nonzero if runtime relocations must be applied;
 119        bit 1 will be set if the runtime relocations require non-local
 120        name resolution.  ALIGN is the required alignment of the data.  */
 121     void (* select_section) (tree, int, unsigned HOST_WIDE_INT);
 122
 123     /* Select and switch to a section for X with MODE.  ALIGN is
 124        the desired alignment of the data.  */
 125     void (* select_rtx_section) (enum machine_mode, rtx,
 126                                  unsigned HOST_WIDE_INT);
 127
 128     /* Select a unique section name for DECL.  RELOC is the same as
 129        for SELECT_SECTION.  */
 130     void (* unique_section) (tree, int);
 131
 132     /* Output a constructor for a symbol with a given priority.  */
 133     void (* constructor) (rtx, int);
 134
 135     /* Output a destructor for a symbol with a given priority.  */
 136     void (* destructor) (rtx, int);
 137
 138     /* Output the assembler code for a thunk function.  THUNK_DECL is the
 139        declaration for the thunk function itself, FUNCTION is the decl for
 140        the target function.  DELTA is an immediate constant offset to be
 141        added to THIS.  If VCALL_OFFSET is nonzero, the word at
 142        *(*this + vcall_offset) should be added to THIS.  */
 143     void (* output_mi_thunk) (FILE *file, tree thunk_decl,
 144                               HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset,
 145                               tree function_decl);
 146
 147     /* Determine whether output_mi_thunk would succeed.  */
 148     /* ??? Ideally, this hook would not exist, and success or failure
 149        would be returned from output_mi_thunk directly.  But there's
 150        too much undo-able setup involved in invoking output_mi_thunk.
 151        Could be fixed by making output_mi_thunk emit rtl instead of
 152        text to the output file.  */
 153     bool (* can_output_mi_thunk) (tree thunk_decl, HOST_WIDE_INT delta,
 154                                   HOST_WIDE_INT vcall_offset,
 155                                   tree function_decl);
 156
 157     /* Output any boilerplate text needed at the beginning of a
 158        translation unit.  */
 159     void (*file_start) (void);
 160
 161     /* Output any boilerplate text needed at the end of a
 162        translation unit.  */
 163     void (*file_end) (void);
 164
 165     /* Output an assembler pseudo-op to declare a library function name
 166        external.  */
 167     void (*external_libcall) (rtx);
 168   } asm_out;
 169
 170   /* Functions relating to instruction scheduling.  */
 171   struct sched
 172   {
 173     /* Given the current cost, COST, of an insn, INSN, calculate and
 174        return a new cost based on its relationship to DEP_INSN through
 175        the dependence LINK.  The default is to make no adjustment.  */
 176     int (* adjust_cost) (rtx insn, rtx link, rtx def_insn, int cost);
 177
 178     /* Adjust the priority of an insn as you see fit.  Returns the new
 179        priority.  */
 180     int (* adjust_priority) (rtx, int);
 181
 182     /* Function which returns the maximum number of insns that can be
 183        scheduled in the same machine cycle.  This must be constant
 184        over an entire compilation.  The default is 1.  */
 185     int (* issue_rate) (void);
 186
 187     /* Calculate how much this insn affects how many more insns we
 188        can emit this cycle.  Default is they all cost the same.  */
 189     int (* variable_issue) (FILE *, int, rtx, int);
 190
 191     /* Initialize machine-dependent scheduling code.  */
 192     void (* md_init) (FILE *, int, int);
 193
 194     /* Finalize machine-dependent scheduling code.  */
 195     void (* md_finish) (FILE *, int);
 196
 197     /* Initialize machine-dependent function while scheduling code.  */
 198     void (* md_init_global) (FILE *, int, int);
 199
 200     /* Finalize machine-dependent function wide scheduling code.  */
 201     void (* md_finish_global) (FILE *, int);
 202
 203     /* Reorder insns in a machine-dependent fashion, in two different
 204        places.  Default does nothing.  */
 205     int (* reorder) (FILE *, int, rtx *, int *, int);
 206     int (* reorder2) (FILE *, int, rtx *, int *, int);
 207
 208     /* The following member value is a pointer to a function called
 209        after evaluation forward dependencies of insns in chain given
 210        by two parameter values (head and tail correspondingly).  */
 211     void (* dependencies_evaluation_hook) (rtx, rtx);
 212
 213     /* The following member value is a pointer to a function returning
 214        nonzero if we should use DFA based scheduling.  The default is
 215        to use the old pipeline scheduler.  */
 216     int (* use_dfa_pipeline_interface) (void);
 217     /* The values of all the following members are used only for the
 218        DFA based scheduler: */
 219     /* The values of the following four members are pointers to
 220        functions used to simplify the automaton descriptions.
 221        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 222        returning insns which are used to change the pipeline hazard
 223        recognizer state when the new simulated processor cycle
 224        correspondingly starts and finishes.  The function defined by
 225        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 226        to initialize the corresponding insns.  The default values of
 227        the members result in not changing the automaton state when
 228        the new simulated processor cycle correspondingly starts and
 229        finishes.  */
 230     void (* init_dfa_pre_cycle_insn) (void);
 231     rtx (* dfa_pre_cycle_insn) (void);
 232     void (* init_dfa_post_cycle_insn) (void);
 233     rtx (* dfa_post_cycle_insn) (void);
 234     /* The following member value is a pointer to a function returning value
 235        which defines how many insns in queue `ready' will we try for
 236        multi-pass scheduling.  If the member value is nonzero and the
 237        function returns positive value, the DFA based scheduler will make
 238        multi-pass scheduling for the first cycle.  In other words, we will
 239        try to choose ready insn which permits to start maximum number of
 240        insns on the same cycle.  */
 241     int (* first_cycle_multipass_dfa_lookahead) (void);
 242     /* The following member value is pointer to a function controlling
 243        what insns from the ready insn queue will be considered for the
 244        multipass insn scheduling.  If the hook returns zero for insn
 245        passed as the parameter, the insn will be not chosen to be
 246        issued.  */
 247     int (* first_cycle_multipass_dfa_lookahead_guard) (rtx);
 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     /* The following member value is a pointer to a function called
 262        by the insn scheduler.  It should return true if there exists a
 263        dependence which is considered costly by the target, between
 264        the insn passed as the first parameter, and the insn passed as
 265        the second parameter.  The third parameter is the INSN_DEPEND
 266        link that represents the dependence between the two insns.  The
 267        fourth argument is the cost of the dependence as estimated by
 268        the scheduler.  The last argument is the distance in cycles
 269        between the already scheduled insn (first parameter) and the
 270        the second insn (second parameter).  */
 271     bool (* is_costly_dependence) (rtx, rtx, rtx, int, int);
 272   } sched;
 273
 274   /* Given two decls, merge their attributes and return the result.  */
 275   tree (* merge_decl_attributes) (tree, tree);
 276
 277   /* Given two types, merge their attributes and return the result.  */
 278   tree (* merge_type_attributes) (tree, tree);
 279
 280   /* Table of machine attributes and functions to handle them.
 281      Ignored if NULL.  */
 282   const struct attribute_spec *attribute_table;
 283
 284   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 285      one if they are compatible and two if they are nearly compatible
 286      (which causes a warning to be generated).  */
 287   int (* comp_type_attributes) (tree type1, tree type2);
 288
 289   /* Assign default attributes to the newly defined TYPE.  */
 290   void (* set_default_type_attributes) (tree type);
 291
 292   /* Insert attributes on the newly created DECL.  */
 293   void (* insert_attributes) (tree decl, tree *attributes);
 294
 295   /* Return true if FNDECL (which has at least one machine attribute)
 296      can be inlined despite its machine attributes, false otherwise.  */
 297   bool (* function_attribute_inlinable_p) (tree fndecl);
 298
 299   /* Return true if bitfields in RECORD_TYPE should follow the
 300      Microsoft Visual C++ bitfield layout rules.  */
 301   bool (* ms_bitfield_layout_p) (tree record_type);
 302
 303   /* Return true if anonymous bitfields affect structure alignment.  */
 304   bool (* align_anon_bitfield) (void);
 305
 306   /* Set up target-specific built-in functions.  */
 307   void (* init_builtins) (void);
 308
 309   /* Expand a target-specific builtin.  */
 310   rtx (* expand_builtin) (tree exp, rtx target, rtx subtarget,
 311                           enum machine_mode mode, int ignore);
 312
 313   /* For a vendor-specific fundamental TYPE, return a pointer to
 314      a statically-allocated string containing the C++ mangling for
 315      TYPE.  In all other cases, return NULL.  */
 316   const char * (* mangle_fundamental_type) (tree type);
 317
 318   /* Make any adjustments to libfunc names needed for this target.  */
 319   void (* init_libfuncs) (void);
 320
 321   /* Given a decl, a section name, and whether the decl initializer
 322      has relocs, choose attributes for the section.  */
 323   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 324   unsigned int (* section_type_flags) (tree, const char *, int);
 325
 326   /* True if new jumps cannot be created, to replace existing ones or
 327      not, at the current point in the compilation.  */
 328   bool (* cannot_modify_jumps_p) (void);
 329
 330   /* Return a register class for which branch target register
 331      optimizations should be applied.  */
 332   int (* branch_target_register_class) (void);
 333
 334   /* Return true if branch target register optimizations should include
 335      callee-saved registers that are not already live during the current
 336      function.  AFTER_PE_GEN is true if prologues and epilogues have
 337      already been generated.  */
 338   bool (* branch_target_register_callee_saved) (bool after_pe_gen);
 339
 340   /* True if the constant X cannot be placed in the constant pool.  */
 341   bool (* cannot_force_const_mem) (rtx);
 342
 343   /* True if the insn X cannot be duplicated.  */
 344   bool (* cannot_copy_insn_p) (rtx);
 345
 346   /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS.  */
 347   rtx (* delegitimize_address) (rtx);
 348
 349   /* True if it is OK to do sibling call optimization for the specified
 350      call expression EXP.  DECL will be the called function, or NULL if
 351      this is an indirect call.  */
 352   bool (*function_ok_for_sibcall) (tree decl, tree exp);
 353
 354   /* True if EXP should be placed in a "small data" section.  */
 355   bool (* in_small_data_p) (tree);
 356
 357   /* True if EXP names an object for which name resolution must resolve
 358      to the current module.  */
 359   bool (* binds_local_p) (tree);
 360
 361   /* Do something target-specific to record properties of the DECL into
 362      the associated SYMBOL_REF.  */
 363   void (* encode_section_info) (tree, rtx, int);
 364
 365   /* Undo the effects of encode_section_info on the symbol string.  */
 366   const char * (* strip_name_encoding) (const char *);
 367
 368   /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))).  */
 369   bool (* valid_pointer_mode) (enum machine_mode mode);
 370
 371   /* True if a vector is opaque.  */
 372   bool (* vector_opaque_p) (tree);
 373
 374   /* Compute a (partial) cost for rtx X.  Return true if the complete
 375      cost has been computed, and false if subexpressions should be
 376      scanned.  In either case, *TOTAL contains the cost result.  */
 377   /* Note that CODE and OUTER_CODE ought to be RTX_CODE, but that's
 378      not necessarily defined at this point.  */
 379   bool (* rtx_costs) (rtx x, int code, int outer_code, int *total);
 380
 381   /* Compute the cost of X, used as an address.  Never called with
 382      invalid addresses.  */
 383   int (* address_cost) (rtx x);
 384
 385   /* Given a register, this hook should return a parallel of registers
 386      to represent where to find the register pieces.  Define this hook
 387      if the register and its mode are represented in Dwarf in
 388      non-contiguous locations, or if the register should be
 389      represented in more than one register in Dwarf.  Otherwise, this
 390      hook should return NULL_RTX.  */
 391   rtx (* dwarf_register_span) (rtx);
 392
 393   /* Fetch the fixed register(s) which hold condition codes, for
 394      targets where it makes sense to look for duplicate assignments to
 395      the condition codes.  This should return true if there is such a
 396      register, false otherwise.  The arguments should be set to the
 397      fixed register numbers.  Up to two condition code registers are
 398      supported.  If there is only one for this target, the int pointed
 399      at by the second argument should be set to -1.  */
 400   bool (* fixed_condition_code_regs) (unsigned int *, unsigned int *);
 401
 402   /* If two condition code modes are compatible, return a condition
 403      code mode which is compatible with both, such that a comparison
 404      done in the returned mode will work for both of the original
 405      modes.  If the condition code modes are not compatible, return
 406      VOIDmode.  */
 407   enum machine_mode (* cc_modes_compatible) (enum machine_mode,
 408                                              enum machine_mode);
 409
 410   /* Do machine-dependent code transformations.  Called just before
 411      delayed-branch scheduling.  */
 412   void (* machine_dependent_reorg) (void);
 413
 414   /* Create the __builtin_va_list type.  */
 415   tree (* build_builtin_va_list) (void);
 416
 417   /* Gimplifies a VA_ARG_EXPR.  */
 418   tree (* gimplify_va_arg_expr) (tree valist, tree type, tree *pre_p,
 419                                  tree *post_p);
 420
 421   /* Validity-checking routines for PCH files, target-specific.
 422      get_pch_validity returns a pointer to the data to be stored,
 423      and stores the size in its argument.  pch_valid_p gets the same
 424      information back and returns NULL if the PCH is valid,
 425      or an error message if not.
 426   */
 427   void * (* get_pch_validity) (size_t *);
 428   const char * (* pch_valid_p) (const void *, size_t);
 429
 430   /* True if the compiler should give an enum type only as many
 431      bytes as it takes to represent the range of possible values of
 432      that type.  */
 433   bool (* default_short_enums) (void);
 434
 435   /* This target hook returns an rtx that is used to store the address
 436      of the current frame into the built-in setjmp buffer.  */
 437   rtx (* builtin_setjmp_frame_value) (void);
 438
 439   /* This target hook should add STRING_CST trees for any hard regs
 440      the port wishes to automatically clobber for all asms.  */
 441   tree (* md_asm_clobbers) (tree);
 442
 443   /* Functions relating to calls - argument passing, returns, etc.  */
 444   struct calls {
 445     bool (*promote_function_args) (tree fntype);
 446     bool (*promote_function_return) (tree fntype);
 447     bool (*promote_prototypes) (tree fntype);
 448     rtx (*struct_value_rtx) (tree fndecl, int incoming);
 449     bool (*return_in_memory) (tree type, tree fndecl);
 450     bool (*return_in_msb) (tree type);
 451
 452     /* Return true if a parameter must be passed by reference.  TYPE may
 453        be null if this is a libcall.  CA may be null if this query is
 454        from __builtin_va_arg.  */
 455     bool (*pass_by_reference) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 456                                tree type, bool named_arg);
 457
 458     rtx (*expand_builtin_saveregs) (void);
 459     /* Returns pretend_argument_size.  */
 460     void (*setup_incoming_varargs) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 461                                     tree type, int *pretend_arg_size,
 462                                     int second_time);
 463     bool (*strict_argument_naming) (CUMULATIVE_ARGS *ca);
 464     /* Returns true if we should use
 465        targetm.calls.setup_incoming_varargs() and/or
 466        targetm.calls.strict_argument_naming().  */
 467     bool (*pretend_outgoing_varargs_named) (CUMULATIVE_ARGS *ca);
 468
 469     /* Given a complex type T, return true if a parameter of type T
 470        should be passed as two scalars.  */
 471     bool (* split_complex_arg) (tree type);
 472
 473     /* Return true if type T, mode MODE, may not be passed in registers,
 474        but must be passed on the stack.  */
 475     /* ??? This predicate should be applied strictly after pass-by-reference.
 476        Need audit to verify that this is the case.  */
 477     bool (* must_pass_in_stack) (enum machine_mode mode, tree t);
 478   } calls;
 479
 480   /* Functions specific to the C++ frontend.  */
 481   struct cxx {
 482     /* Return the integer type used for guard variables.  */
 483     tree (*guard_type) (void);
 484     /* Return true if only the low bit of the guard should be tested.  */
 485     bool (*guard_mask_bit) (void);
 486     /* Returns the size of the array cookie for an array of type.  */
 487     tree (*get_cookie_size) (tree);
 488     /* Returns true if the element size should be stored in the
 489        array cookie.  */
 490     bool (*cookie_has_size) (void);
 491     /* Allows backends to perform additional processing when
 492        deciding if a class should be exported or imported.  */
 493     int (*import_export_class) (tree, int);
 494   } cxx;
 495
 496   /* Leave the boolean fields at the end.  */
 497
 498   /* True if arbitrary sections are supported.  */
 499   bool have_named_sections;
 500
 501   /* True if "native" constructors and destructors are supported,
 502      false if we're using collect2 for the job.  */
 503   bool have_ctors_dtors;
 504
 505   /* True if thread-local storage is supported.  */
 506   bool have_tls;
 507
 508   /* True if a small readonly data section is supported.  */
 509   bool have_srodata_section;
 510
 511   /* True if EH frame info sections should be zero-terminated.  */
 512   bool terminate_dw2_eh_frame_info;
 513
 514   /* True if #NO_APP should be emitted at the beginning of
 515      assembly output.  */
 516   bool file_start_app_off;
 517
 518   /* True if output_file_directive should be called for main_input_filename
 519      at the beginning of assembly output.  */
 520   bool file_start_file_directive;
 521
 522   /* True if #pragma redefine_extname is to be supported.  */
 523   bool handle_pragma_redefine_extname;
 524
 525   /* True if #pragma extern_prefix is to be supported.  */
 526   bool handle_pragma_extern_prefix;
 527
 528   /* True if the RTL prologue and epilogue should be expanded after all
 529      passes that modify the instructions (and not merely reorder them)
 530      have been run.  */
 531   bool late_rtl_prologue_epilogue;
 532
 533   /* Leave the boolean fields at the end.  */
 534 };
 535
 536 extern struct gcc_target targetm;
 537
 538 #endif /* GCC_TARGET_H */