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