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 #include "tm.h"
  48
  49 struct gcc_target
  50 {
  51   /* Functions that output assembler for the target.  */
  52   struct asm_out
  53   {
  54     /* Opening and closing parentheses for asm expression grouping.  */
  55     const char *open_paren, *close_paren;
  56
  57     /* Assembler instructions for creating various kinds of integer object.  */
  58     const char *byte_op;
  59     struct asm_int_op
  60     {
  61       const char *hi;
  62       const char *si;
  63       const char *di;
  64       const char *ti;
  65     } aligned_op, unaligned_op;
  66
  67     /* Try to output the assembler code for an integer object whose
  68        value is given by X.  SIZE is the size of the object in bytes and
  69        ALIGNED_P indicates whether it is aligned.  Return true if
  70        successful.  Only handles cases for which BYTE_OP, ALIGNED_OP
  71        and UNALIGNED_OP are NULL.  */
  72     bool (* integer) (rtx x, unsigned int size, int aligned_p);
  73
  74     /* Output code that will globalize a label.  */
  75     void (* globalize_label) (FILE *, const char *);
  76
  77     /* Output code that will emit a label for unwind info, if this
  78        target requires such labels.  Second argument is the decl the
  79        unwind info is associated with, third is is a boolean: true if
  80        this is only a placeholder for an omitted FDE. */
  81     void (* unwind_label ) (FILE *, tree, int);
  82
  83     /* Output an internal label.  */
  84     void (* internal_label) (FILE *, const char *, unsigned long);
  85
  86     /* Emit an assembler directive to set visibility for the symbol
  87        associated with the tree decl.  */
  88     void (* visibility) (tree, int);
  89
  90     /* Output the assembler code for entry to a function.  */
  91     void (* function_prologue) (FILE *, HOST_WIDE_INT);
  92
  93     /* Output the assembler code for end of prologue.  */
  94     void (* function_end_prologue) (FILE *);
  95
  96     /* Output the assembler code for start of epilogue.  */
  97     void (* function_begin_epilogue) (FILE *);
  98
  99     /* Output the assembler code for function exit.  */
 100     void (* function_epilogue) (FILE *, HOST_WIDE_INT);
 101
 102     /* Switch to an arbitrary section NAME with attributes as
 103        specified by FLAGS.  */
 104     void (* named_section) (const char *, unsigned int);
 105
 106     /* Switch to the section that holds the exception table.  */
 107     void (* exception_section) (void);
 108
 109     /* Switch to the section that holds the exception frames.  */
 110     void (* eh_frame_section) (void);
 111
 112     /* Select and switch to a section for EXP.  It may be a DECL or a
 113        constant.  RELOC is nonzero if runtime relocations must be applied;
 114        bit 1 will be set if the runtime relocations require non-local
 115        name resolution.  ALIGN is the required alignment of the data.  */
 116     void (* select_section) (tree, int, unsigned HOST_WIDE_INT);
 117
 118     /* Select and switch to a section for X with MODE.  ALIGN is
 119        the desired alignment of the data.  */
 120     void (* select_rtx_section) (enum machine_mode, rtx,
 121                                  unsigned HOST_WIDE_INT);
 122
 123     /* Select a unique section name for DECL.  RELOC is the same as
 124        for SELECT_SECTION.  */
 125     void (* unique_section) (tree, int);
 126
 127     /* Output a constructor for a symbol with a given priority.  */
 128     void (* constructor) (rtx, int);
 129
 130     /* Output a destructor for a symbol with a given priority.  */
 131     void (* destructor) (rtx, int);
 132
 133     /* Output the assembler code for a thunk function.  THUNK_DECL is the
 134        declaration for the thunk function itself, FUNCTION is the decl for
 135        the target function.  DELTA is an immediate constant offset to be
 136        added to THIS.  If VCALL_OFFSET is nonzero, the word at
 137        *(*this + vcall_offset) should be added to THIS.  */
 138     void (* output_mi_thunk) (FILE *file, tree thunk_decl,
 139                               HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset,
 140                               tree function_decl);
 141
 142     /* Determine whether output_mi_thunk would succeed.  */
 143     /* ??? Ideally, this hook would not exist, and success or failure
 144        would be returned from output_mi_thunk directly.  But there's
 145        too much undo-able setup involved in invoking output_mi_thunk.
 146        Could be fixed by making output_mi_thunk emit rtl instead of
 147        text to the output file.  */
 148     bool (* can_output_mi_thunk) (tree thunk_decl, HOST_WIDE_INT delta,
 149                                   HOST_WIDE_INT vcall_offset,
 150                                   tree function_decl);
 151
 152     /* Output any boilerplate text needed at the beginning of a
 153        translation unit.  */
 154     void (*file_start) (void);
 155
 156     /* Output any boilerplate text needed at the end of a
 157        translation unit.  */
 158     void (*file_end) (void);
 159
 160     /* Output an assembler pseudo-op to declare a library function name
 161        external.  */
 162     void (*external_libcall) (rtx);
 163   } asm_out;
 164
 165   /* Functions relating to instruction scheduling.  */
 166   struct sched
 167   {
 168     /* Given the current cost, COST, of an insn, INSN, calculate and
 169        return a new cost based on its relationship to DEP_INSN through
 170        the dependence LINK.  The default is to make no adjustment.  */
 171     int (* adjust_cost) (rtx insn, rtx link, rtx def_insn, int cost);
 172
 173     /* Adjust the priority of an insn as you see fit.  Returns the new
 174        priority.  */
 175     int (* adjust_priority) (rtx, int);
 176
 177     /* Function which returns the maximum number of insns that can be
 178        scheduled in the same machine cycle.  This must be constant
 179        over an entire compilation.  The default is 1.  */
 180     int (* issue_rate) (void);
 181
 182     /* Calculate how much this insn affects how many more insns we
 183        can emit this cycle.  Default is they all cost the same.  */
 184     int (* variable_issue) (FILE *, int, rtx, int);
 185
 186     /* Initialize machine-dependent scheduling code.  */
 187     void (* md_init) (FILE *, int, int);
 188
 189     /* Finalize machine-dependent scheduling code.  */
 190     void (* md_finish) (FILE *, int);
 191
 192     /* Initialize machine-dependent function while scheduling code.  */
 193     void (* md_init_global) (FILE *, int, int);
 194
 195     /* Finalize machine-dependent function wide scheduling code.  */
 196     void (* md_finish_global) (FILE *, int);
 197
 198     /* Reorder insns in a machine-dependent fashion, in two different
 199        places.  Default does nothing.  */
 200     int (* reorder) (FILE *, int, rtx *, int *, int);
 201     int (* reorder2) (FILE *, int, rtx *, int *, int);
 202
 203     /* The following member value is a pointer to a function called
 204        after evaluation forward dependencies of insns in chain given
 205        by two parameter values (head and tail correspondingly).  */
 206     void (* dependencies_evaluation_hook) (rtx, rtx);
 207
 208     /* The following member value is a pointer to a function returning
 209        nonzero if we should use DFA based scheduling.  The default is
 210        to use the old pipeline scheduler.  */
 211     int (* use_dfa_pipeline_interface) (void);
 212     /* The values of all the following members are used only for the
 213        DFA based scheduler: */
 214     /* The values of the following four members are pointers to
 215        functions used to simplify the automaton descriptions.
 216        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 217        returning insns which are used to change the pipeline hazard
 218        recognizer state when the new simulated processor cycle
 219        correspondingly starts and finishes.  The function defined by
 220        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 221        to initialize the corresponding insns.  The default values of
 222        the members result in not changing the automaton state when
 223        the new simulated processor cycle correspondingly starts and
 224        finishes.  */
 225     void (* init_dfa_pre_cycle_insn) (void);
 226     rtx (* dfa_pre_cycle_insn) (void);
 227     void (* init_dfa_post_cycle_insn) (void);
 228     rtx (* dfa_post_cycle_insn) (void);
 229     /* The following member value is a pointer to a function returning value
 230        which defines how many insns in queue `ready' will we try for
 231        multi-pass scheduling.  if the member value is nonzero and the
 232        function returns positive value, the DFA based scheduler will make
 233        multi-pass scheduling for the first cycle.  In other words, we will
 234        try to choose ready insn which permits to start maximum number of
 235        insns on the same cycle.  */
 236     int (* first_cycle_multipass_dfa_lookahead) (void);
 237     /* The following member value is pointer to a function controlling
 238        what insns from the ready insn queue will be considered for the
 239        multipass insn scheduling.  If the hook returns zero for insn
 240        passed as the parameter, the insn will be not chosen to be
 241        issued.  */
 242     int (* first_cycle_multipass_dfa_lookahead_guard) (rtx);
 243     /* The following member value is pointer to a function called by
 244        the insn scheduler before issuing insn passed as the third
 245        parameter on given cycle.  If the hook returns nonzero, the
 246        insn is not issued on given processors cycle.  Instead of that,
 247        the processor cycle is advanced.  If the value passed through
 248        the last parameter is zero, the insn ready queue is not sorted
 249        on the new cycle start as usually.  The first parameter passes
 250        file for debugging output.  The second one passes the scheduler
 251        verbose level of the debugging output.  The forth and the fifth
 252        parameter values are correspondingly processor cycle on which
 253        the previous insn has been issued and the current processor
 254        cycle.  */
 255     int (* dfa_new_cycle) (FILE *, int, rtx, int, int, int *);
 256     /* The values of the following members are pointers to functions
 257        used to improve the first cycle multipass scheduling by
 258        inserting nop insns.  dfa_scheduler_bubble gives a function
 259        returning a nop insn with given index.  The indexes start with
 260        zero.  The function should return NULL if there are no more nop
 261        insns with indexes greater than given index.  To initialize the
 262        nop insn the function given by member
 263        init_dfa_scheduler_bubbles is used.  The default values of the
 264        members result in not inserting nop insns during the multipass
 265        scheduling.  */
 266     void (* init_dfa_bubbles) (void);
 267     rtx (* dfa_bubble) (int);
 268     /* The following member value is a pointer to a function called
 269        by the insn scheduler.  It should return true if there exists a
 270        dependence which is considered costly by the target, between
 271        the insn passed as the first parameter, and the insn passed as
 272        the second parameter.  The third parameter is the INSN_DEPEND
 273        link that represents the dependence between the two insns.  The
 274        fourth argument is the cost of the dependence as estimated by
 275        the scheduler.  The last argument is the distance in cycles
 276        between the already scheduled insn (first parameter) and the
 277        the second insn (second parameter).  */
 278     bool (* is_costly_dependence) (rtx, rtx, rtx, int, int);
 279   } sched;
 280
 281   /* Given two decls, merge their attributes and return the result.  */
 282   tree (* merge_decl_attributes) (tree, tree);
 283
 284   /* Given two types, merge their attributes and return the result.  */
 285   tree (* merge_type_attributes) (tree, tree);
 286
 287   /* Table of machine attributes and functions to handle them.
 288      Ignored if NULL.  */
 289   const struct attribute_spec *attribute_table;
 290
 291   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 292      one if they are compatible and two if they are nearly compatible
 293      (which causes a warning to be generated).  */
 294   int (* comp_type_attributes) (tree type1, tree type2);
 295
 296   /* Assign default attributes to the newly defined TYPE.  */
 297   void (* set_default_type_attributes) (tree type);
 298
 299   /* Insert attributes on the newly created DECL.  */
 300   void (* insert_attributes) (tree decl, tree *attributes);
 301
 302   /* Return true if FNDECL (which has at least one machine attribute)
 303      can be inlined despite its machine attributes, false otherwise.  */
 304   bool (* function_attribute_inlinable_p) (tree fndecl);
 305
 306   /* Return true if bitfields in RECORD_TYPE should follow the
 307      Microsoft Visual C++ bitfield layout rules.  */
 308   bool (* ms_bitfield_layout_p) (tree record_type);
 309
 310   /* Set up target-specific built-in functions.  */
 311   void (* init_builtins) (void);
 312
 313   /* Expand a target-specific builtin.  */
 314   rtx (* expand_builtin) (tree exp, rtx target, rtx subtarget,
 315                           enum machine_mode mode, int ignore);
 316
 317   /* Make any adjustments to libfunc names needed for this target.  */
 318   void (* init_libfuncs) (void);
 319
 320   /* Given a decl, a section name, and whether the decl initializer
 321      has relocs, choose attributes for the section.  */
 322   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 323   unsigned int (* section_type_flags) (tree, const char *, int);
 324
 325   /* True if new jumps cannot be created, to replace existing ones or
 326      not, at the current point in the compilation.  */
 327   bool (* cannot_modify_jumps_p) (void);
 328
 329   /* Return a register class for which branch target register
 330      optimizations should be applied.  */
 331   int (* branch_target_register_class) (void);
 332
 333   /* Return true if branch target register optimizations should include
 334      callee-saved registers that are not already live during the current
 335      function.  AFTER_PE_GEN is true if prologues and epilogues have
 336      already been generated.  */
 337   bool (* branch_target_register_callee_saved) (bool after_pe_gen);
 338
 339   /* True if the constant X cannot be placed in the constant pool.  */
 340   bool (* cannot_force_const_mem) (rtx);
 341
 342   /* True if the insn X cannot be duplicated.  */
 343   bool (* cannot_copy_insn_p) (rtx);
 344
 345   /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS.  */
 346   rtx (* delegitimize_address) (rtx);
 347
 348   /* True if it is OK to do sibling call optimization for the specified
 349      call expression EXP.  DECL will be the called function, or NULL if
 350      this is an indirect call.  */
 351   bool (*function_ok_for_sibcall) (tree decl, tree exp);
 352
 353   /* True if EXP should be placed in a "small data" section.  */
 354   bool (* in_small_data_p) (tree);
 355
 356   /* True if EXP names an object for which name resolution must resolve
 357      to the current module.  */
 358   bool (* binds_local_p) (tree);
 359
 360   /* Do something target-specific to record properties of the DECL into
 361      the associated SYMBOL_REF.  */
 362   void (* encode_section_info) (tree, rtx, int);
 363
 364   /* Undo the effects of encode_section_info on the symbol string.  */
 365   const char * (* strip_name_encoding) (const char *);
 366
 367   /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))).  */
 368   bool (* valid_pointer_mode) (enum machine_mode mode);
 369
 370   /* True if a vector is opaque.  */
 371   bool (* vector_opaque_p) (tree);
 372
 373   /* Compute a (partial) cost for rtx X.  Return true if the complete
 374      cost has been computed, and false if subexpressions should be
 375      scanned.  In either case, *TOTAL contains the cost result.  */
 376   /* Note that CODE and OUTER_CODE ought to be RTX_CODE, but that's
 377      not necessarily defined at this point.  */
 378   bool (* rtx_costs) (rtx x, int code, int outer_code, int *total);
 379
 380   /* Compute the cost of X, used as an address.  Never called with
 381      invalid addresses.  */
 382   int (* address_cost) (rtx x);
 383
 384   /* Given a register, this hook should return a parallel of registers
 385      to represent where to find the register pieces.  Define this hook
 386      if the register and its mode are represented in Dwarf in
 387      non-contiguous locations, or if the register should be
 388      represented in more than one register in Dwarf.  Otherwise, this
 389      hook should return NULL_RTX.  */
 390   rtx (* dwarf_register_span) (rtx);
 391
 392   /* Fetch the fixed register(s) which hold condition codes, for
 393      targets where it makes sense to look for duplicate assignments to
 394      the condition codes.  This should return true if there is such a
 395      register, false otherwise.  The arguments should be set to the
 396      fixed register numbers.  Up to two condition code registers are
 397      supported.  If there is only one for this target, the int pointed
 398      at by the second argument should be set to -1.  */
 399   bool (* fixed_condition_code_regs) (unsigned int *, unsigned int *);
 400
 401   /* If two condition code modes are compatible, return a condition
 402      code mode which is compatible with both, such that a comparison
 403      done in the returned mode will work for both of the original
 404      modes.  If the condition code modes are not compatible, return
 405      VOIDmode.  */
 406   enum machine_mode (* cc_modes_compatible) (enum machine_mode,
 407                                              enum machine_mode);
 408
 409   /* Do machine-dependent code transformations.  Called just before
 410      delayed-branch scheduling.  */
 411   void (* machine_dependent_reorg) (void);
 412
 413   /* Create the __builtin_va_list type.  */
 414   tree (* build_builtin_va_list) (void);
 415
 416   /* Validity-checking routines for PCH files, target-specific.
 417      get_pch_validity returns a pointer to the data to be stored,
 418      and stores the size in its argument.  pch_valid_p gets the same
 419      information back and returns NULL if the PCH is valid,
 420      or an error message if not.
 421   */
 422   void * (* get_pch_validity) (size_t *);
 423   const char * (* pch_valid_p) (const void *, size_t);
 424
 425   /* True if the compiler should give an enum type only as many
 426      bytes as it takes to represent the range of possible values of
 427      that type.  */
 428   bool (* default_short_enums) (void);
 429
 430   /* This target hook returns an rtx that is used to store the address
 431      of the current frame into the built-in setjmp buffer.  */
 432   rtx (* builtin_setjmp_frame_value) (void);
 433
 434   /* This target hook should add STRING_CST trees for any hard regs
 435      the port wishes to automatically clobber for all asms.  */
 436   tree (* md_asm_clobbers) (tree);
 437
 438   /* Functions relating to calls - argument passing, returns, etc.  */
 439   struct calls {
 440     bool (*promote_function_args) (tree fntype);
 441     bool (*promote_function_return) (tree fntype);
 442     bool (*promote_prototypes) (tree fntype);
 443     rtx (*struct_value_rtx) (tree fndecl, int incoming);
 444     bool (*return_in_memory) (tree type, tree fndecl);
 445     bool (*return_in_msb) (tree type);
 446     rtx (*expand_builtin_saveregs) (void);
 447     /* Returns pretend_argument_size.  */
 448     void (*setup_incoming_varargs) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 449                                     tree type, int *pretend_arg_size,
 450                                     int second_time);
 451     bool (*strict_argument_naming) (CUMULATIVE_ARGS *ca);
 452     /* Returns true if we should use
 453        targetm.calls.setup_incoming_varargs() and/or
 454        targetm.calls.strict_argument_naming().  */
 455     bool (*pretend_outgoing_varargs_named) (CUMULATIVE_ARGS *ca);
 456
 457     /* Given a complex type T, return true if a parameter of type T
 458        should be passed as two scalars.  */
 459     bool (* split_complex_arg) (tree type);
 460   } calls;
 461
 462   /* Leave the boolean fields at the end.  */
 463
 464   /* True if arbitrary sections are supported.  */
 465   bool have_named_sections;
 466
 467   /* True if "native" constructors and destructors are supported,
 468      false if we're using collect2 for the job.  */
 469   bool have_ctors_dtors;
 470
 471   /* True if thread-local storage is supported.  */
 472   bool have_tls;
 473
 474   /* True if a small readonly data section is supported.  */
 475   bool have_srodata_section;
 476
 477   /* True if EH frame info sections should be zero-terminated.  */
 478   bool terminate_dw2_eh_frame_info;
 479
 480   /* True if #NO_APP should be emitted at the beginning of
 481      assembly output.  */
 482   bool file_start_app_off;
 483
 484   /* True if output_file_directive should be called for main_input_filename
 485      at the beginning of assembly output.  */
 486   bool file_start_file_directive;
 487
 488   /* Leave the boolean fields at the end.  */
 489 };
 490
 491 extern struct gcc_target targetm;