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     /* Tell assembler to switch to the readonly data section associated
 136        with function DECL.  */
 137     void (* function_rodata_section) (tree);
 138
 139     /* Output a constructor for a symbol with a given priority.  */
 140     void (* constructor) (rtx, int);
 141
 142     /* Output a destructor for a symbol with a given priority.  */
 143     void (* destructor) (rtx, int);
 144
 145     /* Output the assembler code for a thunk function.  THUNK_DECL is the
 146        declaration for the thunk function itself, FUNCTION is the decl for
 147        the target function.  DELTA is an immediate constant offset to be
 148        added to THIS.  If VCALL_OFFSET is nonzero, the word at
 149        *(*this + vcall_offset) should be added to THIS.  */
 150     void (* output_mi_thunk) (FILE *file, tree thunk_decl,
 151                               HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset,
 152                               tree function_decl);
 153
 154     /* Determine whether output_mi_thunk would succeed.  */
 155     /* ??? Ideally, this hook would not exist, and success or failure
 156        would be returned from output_mi_thunk directly.  But there's
 157        too much undo-able setup involved in invoking output_mi_thunk.
 158        Could be fixed by making output_mi_thunk emit rtl instead of
 159        text to the output file.  */
 160     bool (* can_output_mi_thunk) (tree thunk_decl, HOST_WIDE_INT delta,
 161                                   HOST_WIDE_INT vcall_offset,
 162                                   tree function_decl);
 163
 164     /* Output any boilerplate text needed at the beginning of a
 165        translation unit.  */
 166     void (*file_start) (void);
 167
 168     /* Output any boilerplate text needed at the end of a
 169        translation unit.  */
 170     void (*file_end) (void);
 171
 172     /* Output an assembler pseudo-op to declare a library function name
 173        external.  */
 174     void (*external_libcall) (rtx);
 175   } asm_out;
 176
 177   /* Functions relating to instruction scheduling.  */
 178   struct sched
 179   {
 180     /* Given the current cost, COST, of an insn, INSN, calculate and
 181        return a new cost based on its relationship to DEP_INSN through
 182        the dependence LINK.  The default is to make no adjustment.  */
 183     int (* adjust_cost) (rtx insn, rtx link, rtx def_insn, int cost);
 184
 185     /* Adjust the priority of an insn as you see fit.  Returns the new
 186        priority.  */
 187     int (* adjust_priority) (rtx, int);
 188
 189     /* Function which returns the maximum number of insns that can be
 190        scheduled in the same machine cycle.  This must be constant
 191        over an entire compilation.  The default is 1.  */
 192     int (* issue_rate) (void);
 193
 194     /* Calculate how much this insn affects how many more insns we
 195        can emit this cycle.  Default is they all cost the same.  */
 196     int (* variable_issue) (FILE *, int, rtx, int);
 197
 198     /* Initialize machine-dependent scheduling code.  */
 199     void (* md_init) (FILE *, int, int);
 200
 201     /* Finalize machine-dependent scheduling code.  */
 202     void (* md_finish) (FILE *, int);
 203
 204     /* Initialize machine-dependent function while scheduling code.  */
 205     void (* md_init_global) (FILE *, int, int);
 206
 207     /* Finalize machine-dependent function wide scheduling code.  */
 208     void (* md_finish_global) (FILE *, int);
 209
 210     /* Reorder insns in a machine-dependent fashion, in two different
 211        places.  Default does nothing.  */
 212     int (* reorder) (FILE *, int, rtx *, int *, int);
 213     int (* reorder2) (FILE *, int, rtx *, int *, int);
 214
 215     /* The following member value is a pointer to a function called
 216        after evaluation forward dependencies of insns in chain given
 217        by two parameter values (head and tail correspondingly).  */
 218     void (* dependencies_evaluation_hook) (rtx, rtx);
 219
 220     /* The values of the following four members are pointers to
 221        functions used to simplify the automaton descriptions.
 222        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 223        returning insns which are used to change the pipeline hazard
 224        recognizer state when the new simulated processor cycle
 225        correspondingly starts and finishes.  The function defined by
 226        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 227        to initialize the corresponding insns.  The default values of
 228        the members result in not changing the automaton state when
 229        the new simulated processor cycle correspondingly starts and
 230        finishes.  */
 231     void (* init_dfa_pre_cycle_insn) (void);
 232     rtx (* dfa_pre_cycle_insn) (void);
 233     void (* init_dfa_post_cycle_insn) (void);
 234     rtx (* dfa_post_cycle_insn) (void);
 235
 236     /* The following member value is a pointer to a function returning value
 237        which defines how many insns in queue `ready' will we try for
 238        multi-pass scheduling.  If the member value is nonzero and the
 239        function returns positive value, the DFA based scheduler will make
 240        multi-pass scheduling for the first cycle.  In other words, we will
 241        try to choose ready insn which permits to start maximum number of
 242        insns on the same cycle.  */
 243     int (* first_cycle_multipass_dfa_lookahead) (void);
 244
 245     /* The following member value is pointer to a function controlling
 246        what insns from the ready insn queue will be considered for the
 247        multipass insn scheduling.  If the hook returns zero for insn
 248        passed as the parameter, the insn will be not chosen to be
 249        issued.  */
 250     int (* first_cycle_multipass_dfa_lookahead_guard) (rtx);
 251
 252     /* The following member value is pointer to a function called by
 253        the insn scheduler before issuing insn passed as the third
 254        parameter on given cycle.  If the hook returns nonzero, the
 255        insn is not issued on given processors cycle.  Instead of that,
 256        the processor cycle is advanced.  If the value passed through
 257        the last parameter is zero, the insn ready queue is not sorted
 258        on the new cycle start as usually.  The first parameter passes
 259        file for debugging output.  The second one passes the scheduler
 260        verbose level of the debugging output.  The forth and the fifth
 261        parameter values are correspondingly processor cycle on which
 262        the previous insn has been issued and the current processor
 263        cycle.  */
 264     int (* dfa_new_cycle) (FILE *, int, rtx, int, int, int *);
 265
 266     /* The following member value is a pointer to a function called
 267        by the insn scheduler.  It should return true if there exists a
 268        dependence which is considered costly by the target, between
 269        the insn passed as the first parameter, and the insn passed as
 270        the second parameter.  The third parameter is the INSN_DEPEND
 271        link that represents the dependence between the two insns.  The
 272        fourth argument is the cost of the dependence as estimated by
 273        the scheduler.  The last argument is the distance in cycles
 274        between the already scheduled insn (first parameter) and the
 275        the second insn (second parameter).  */
 276     bool (* is_costly_dependence) (rtx, rtx, rtx, int, int);
 277   } sched;
 278
 279   /* Return machine mode for filter value. */
 280   enum machine_mode (* eh_return_filter_mode) (void);
 281
 282   /* Given two decls, merge their attributes and return the result.  */
 283   tree (* merge_decl_attributes) (tree, tree);
 284
 285   /* Given two types, merge their attributes and return the result.  */
 286   tree (* merge_type_attributes) (tree, tree);
 287
 288   /* Table of machine attributes and functions to handle them.
 289      Ignored if NULL.  */
 290   const struct attribute_spec *attribute_table;
 291
 292   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 293      one if they are compatible and two if they are nearly compatible
 294      (which causes a warning to be generated).  */
 295   int (* comp_type_attributes) (tree type1, tree type2);
 296
 297   /* Assign default attributes to the newly defined TYPE.  */
 298   void (* set_default_type_attributes) (tree type);
 299
 300   /* Insert attributes on the newly created DECL.  */
 301   void (* insert_attributes) (tree decl, tree *attributes);
 302
 303   /* Return true if FNDECL (which has at least one machine attribute)
 304      can be inlined despite its machine attributes, false otherwise.  */
 305   bool (* function_attribute_inlinable_p) (tree fndecl);
 306
 307   /* Return true if bitfields in RECORD_TYPE should follow the
 308      Microsoft Visual C++ bitfield layout rules.  */
 309   bool (* ms_bitfield_layout_p) (tree record_type);
 310
 311   /* Return true if anonymous bitfields affect structure alignment.  */
 312   bool (* align_anon_bitfield) (void);
 313
 314   /* Set up target-specific built-in functions.  */
 315   void (* init_builtins) (void);
 316
 317   /* Expand a target-specific builtin.  */
 318   rtx (* expand_builtin) (tree exp, rtx target, rtx subtarget,
 319                           enum machine_mode mode, int ignore);
 320
 321   /* For a vendor-specific fundamental TYPE, return a pointer to
 322      a statically-allocated string containing the C++ mangling for
 323      TYPE.  In all other cases, return NULL.  */
 324   const char * (* mangle_fundamental_type) (tree type);
 325
 326   /* Make any adjustments to libfunc names needed for this target.  */
 327   void (* init_libfuncs) (void);
 328
 329   /* Given a decl, a section name, and whether the decl initializer
 330      has relocs, choose attributes for the section.  */
 331   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 332   unsigned int (* section_type_flags) (tree, const char *, int);
 333
 334   /* True if new jumps cannot be created, to replace existing ones or
 335      not, at the current point in the compilation.  */
 336   bool (* cannot_modify_jumps_p) (void);
 337
 338   /* Return a register class for which branch target register
 339      optimizations should be applied.  */
 340   int (* branch_target_register_class) (void);
 341
 342   /* Return true if branch target register optimizations should include
 343      callee-saved registers that are not already live during the current
 344      function.  AFTER_PE_GEN is true if prologues and epilogues have
 345      already been generated.  */
 346   bool (* branch_target_register_callee_saved) (bool after_pe_gen);
 347
 348   /* True if the constant X cannot be placed in the constant pool.  */
 349   bool (* cannot_force_const_mem) (rtx);
 350
 351   /* True if the insn X cannot be duplicated.  */
 352   bool (* cannot_copy_insn_p) (rtx);
 353
 354   /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS.  */
 355   rtx (* delegitimize_address) (rtx);
 356
 357   /* True if it is OK to do sibling call optimization for the specified
 358      call expression EXP.  DECL will be the called function, or NULL if
 359      this is an indirect call.  */
 360   bool (*function_ok_for_sibcall) (tree decl, tree exp);
 361
 362   /* True if EXP should be placed in a "small data" section.  */
 363   bool (* in_small_data_p) (tree);
 364
 365   /* True if EXP names an object for which name resolution must resolve
 366      to the current module.  */
 367   bool (* binds_local_p) (tree);
 368
 369   /* Do something target-specific to record properties of the DECL into
 370      the associated SYMBOL_REF.  */
 371   void (* encode_section_info) (tree, rtx, int);
 372
 373   /* Undo the effects of encode_section_info on the symbol string.  */
 374   const char * (* strip_name_encoding) (const char *);
 375
 376   /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))).  */
 377   bool (* valid_pointer_mode) (enum machine_mode mode);
 378
 379   /* True if a vector is opaque.  */
 380   bool (* vector_opaque_p) (tree);
 381
 382   /* Compute a (partial) cost for rtx X.  Return true if the complete
 383      cost has been computed, and false if subexpressions should be
 384      scanned.  In either case, *TOTAL contains the cost result.  */
 385   /* Note that CODE and OUTER_CODE ought to be RTX_CODE, but that's
 386      not necessarily defined at this point.  */
 387   bool (* rtx_costs) (rtx x, int code, int outer_code, int *total);
 388
 389   /* Compute the cost of X, used as an address.  Never called with
 390      invalid addresses.  */
 391   int (* address_cost) (rtx x);
 392
 393   /* Given a register, this hook should return a parallel of registers
 394      to represent where to find the register pieces.  Define this hook
 395      if the register and its mode are represented in Dwarf in
 396      non-contiguous locations, or if the register should be
 397      represented in more than one register in Dwarf.  Otherwise, this
 398      hook should return NULL_RTX.  */
 399   rtx (* dwarf_register_span) (rtx);
 400
 401   /* Fetch the fixed register(s) which hold condition codes, for
 402      targets where it makes sense to look for duplicate assignments to
 403      the condition codes.  This should return true if there is such a
 404      register, false otherwise.  The arguments should be set to the
 405      fixed register numbers.  Up to two condition code registers are
 406      supported.  If there is only one for this target, the int pointed
 407      at by the second argument should be set to -1.  */
 408   bool (* fixed_condition_code_regs) (unsigned int *, unsigned int *);
 409
 410   /* If two condition code modes are compatible, return a condition
 411      code mode which is compatible with both, such that a comparison
 412      done in the returned mode will work for both of the original
 413      modes.  If the condition code modes are not compatible, return
 414      VOIDmode.  */
 415   enum machine_mode (* cc_modes_compatible) (enum machine_mode,
 416                                              enum machine_mode);
 417
 418   /* Do machine-dependent code transformations.  Called just before
 419      delayed-branch scheduling.  */
 420   void (* machine_dependent_reorg) (void);
 421
 422   /* Create the __builtin_va_list type.  */
 423   tree (* build_builtin_va_list) (void);
 424
 425   /* Gimplifies a VA_ARG_EXPR.  */
 426   tree (* gimplify_va_arg_expr) (tree valist, tree type, tree *pre_p,
 427                                  tree *post_p);
 428
 429   /* Validity-checking routines for PCH files, target-specific.
 430      get_pch_validity returns a pointer to the data to be stored,
 431      and stores the size in its argument.  pch_valid_p gets the same
 432      information back and returns NULL if the PCH is valid,
 433      or an error message if not.
 434   */
 435   void * (* get_pch_validity) (size_t *);
 436   const char * (* pch_valid_p) (const void *, size_t);
 437
 438   /* True if the compiler should give an enum type only as many
 439      bytes as it takes to represent the range of possible values of
 440      that type.  */
 441   bool (* default_short_enums) (void);
 442
 443   /* This target hook returns an rtx that is used to store the address
 444      of the current frame into the built-in setjmp buffer.  */
 445   rtx (* builtin_setjmp_frame_value) (void);
 446
 447   /* This target hook should add STRING_CST trees for any hard regs
 448      the port wishes to automatically clobber for all asms.  */
 449   tree (* md_asm_clobbers) (tree);
 450
 451   /* Functions relating to calls - argument passing, returns, etc.  */
 452   struct calls {
 453     bool (*promote_function_args) (tree fntype);
 454     bool (*promote_function_return) (tree fntype);
 455     bool (*promote_prototypes) (tree fntype);
 456     rtx (*struct_value_rtx) (tree fndecl, int incoming);
 457     bool (*return_in_memory) (tree type, tree fndecl);
 458     bool (*return_in_msb) (tree type);
 459
 460     /* Return true if a parameter must be passed by reference.  TYPE may
 461        be null if this is a libcall.  CA may be null if this query is
 462        from __builtin_va_arg.  */
 463     bool (*pass_by_reference) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 464                                tree type, bool named_arg);
 465
 466     rtx (*expand_builtin_saveregs) (void);
 467     /* Returns pretend_argument_size.  */
 468     void (*setup_incoming_varargs) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 469                                     tree type, int *pretend_arg_size,
 470                                     int second_time);
 471     bool (*strict_argument_naming) (CUMULATIVE_ARGS *ca);
 472     /* Returns true if we should use
 473        targetm.calls.setup_incoming_varargs() and/or
 474        targetm.calls.strict_argument_naming().  */
 475     bool (*pretend_outgoing_varargs_named) (CUMULATIVE_ARGS *ca);
 476
 477     /* Given a complex type T, return true if a parameter of type T
 478        should be passed as two scalars.  */
 479     bool (* split_complex_arg) (tree type);
 480
 481     /* Return true if type T, mode MODE, may not be passed in registers,
 482        but must be passed on the stack.  */
 483     /* ??? This predicate should be applied strictly after pass-by-reference.
 484        Need audit to verify that this is the case.  */
 485     bool (* must_pass_in_stack) (enum machine_mode mode, tree t);
 486   } calls;
 487
 488   /* Functions specific to the C++ frontend.  */
 489   struct cxx {
 490     /* Return the integer type used for guard variables.  */
 491     tree (*guard_type) (void);
 492     /* Return true if only the low bit of the guard should be tested.  */
 493     bool (*guard_mask_bit) (void);
 494     /* Returns the size of the array cookie for an array of type.  */
 495     tree (*get_cookie_size) (tree);
 496     /* Returns true if the element size should be stored in the
 497        array cookie.  */
 498     bool (*cookie_has_size) (void);
 499     /* Allows backends to perform additional processing when
 500        deciding if a class should be exported or imported.  */
 501     int (*import_export_class) (tree, int);
 502     /* Returns true if constructors and destructors return "this".  */
 503     bool (*cdtor_returns_this) (void);
 504   } cxx;
 505
 506   /* Leave the boolean fields at the end.  */
 507
 508   /* True if arbitrary sections are supported.  */
 509   bool have_named_sections;
 510
 511   /* True if "native" constructors and destructors are supported,
 512      false if we're using collect2 for the job.  */
 513   bool have_ctors_dtors;
 514
 515   /* True if thread-local storage is supported.  */
 516   bool have_tls;
 517
 518   /* True if a small readonly data section is supported.  */
 519   bool have_srodata_section;
 520
 521   /* True if EH frame info sections should be zero-terminated.  */
 522   bool terminate_dw2_eh_frame_info;
 523
 524   /* True if #NO_APP should be emitted at the beginning of
 525      assembly output.  */
 526   bool file_start_app_off;
 527
 528   /* True if output_file_directive should be called for main_input_filename
 529      at the beginning of assembly output.  */
 530   bool file_start_file_directive;
 531
 532   /* True if #pragma redefine_extname is to be supported.  */
 533   bool handle_pragma_redefine_extname;
 534
 535   /* True if #pragma extern_prefix is to be supported.  */
 536   bool handle_pragma_extern_prefix;
 537
 538   /* True if the RTL prologue and epilogue should be expanded after all
 539      passes that modify the instructions (and not merely reorder them)
 540      have been run.  */
 541   bool late_rtl_prologue_epilogue;
 542
 543   /* Leave the boolean fields at the end.  */
 544 };
 545
 546 extern struct gcc_target targetm;
 547
 548 #endif /* GCC_TARGET_H */