gcc/target.h

   1 /* Data structure definitions for a generic GCC target.
   2    Copyright (C) 2001, 2002, 2003 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     /* Reorder insns in a machine-dependent fashion, in two different
 187        places.  Default does nothing.  */
 188     int (* reorder) (FILE *, int, rtx *, int *, int);
 189     int (* reorder2) (FILE *, int, rtx *, int *, int);
 190
 191     /* The following member value is a pointer to a function called
 192        after evaluation forward dependencies of insns in chain given
 193        by two parameter values (head and tail correspondingly).  */
 194     void (* dependencies_evaluation_hook) (rtx, rtx);
 195
 196     /* The following member value is a pointer to a function returning
 197        nonzero if we should use DFA based scheduling.  The default is
 198        to use the old pipeline scheduler.  */
 199     int (* use_dfa_pipeline_interface) (void);
 200     /* The values of all the following members are used only for the
 201        DFA based scheduler: */
 202     /* The values of the following four members are pointers to
 203        functions used to simplify the automaton descriptions.
 204        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 205        returning insns which are used to change the pipeline hazard
 206        recognizer state when the new simulated processor cycle
 207        correspondingly starts and finishes.  The function defined by
 208        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 209        to initialize the corresponding insns.  The default values of
 210        the members result in not changing the automaton state when
 211        the new simulated processor cycle correspondingly starts and
 212        finishes.  */
 213     void (* init_dfa_pre_cycle_insn) (void);
 214     rtx (* dfa_pre_cycle_insn) (void);
 215     void (* init_dfa_post_cycle_insn) (void);
 216     rtx (* dfa_post_cycle_insn) (void);
 217     /* The following member value is a pointer to a function returning value
 218        which defines how many insns in queue `ready' will we try for
 219        multi-pass scheduling.  if the member value is nonzero and the
 220        function returns positive value, the DFA based scheduler will make
 221        multi-pass scheduling for the first cycle.  In other words, we will
 222        try to choose ready insn which permits to start maximum number of
 223        insns on the same cycle.  */
 224     int (* first_cycle_multipass_dfa_lookahead) (void);
 225     /* The following member value is pointer to a function controlling
 226        what insns from the ready insn queue will be considered for the
 227        multipass insn scheduling.  If the hook returns zero for insn
 228        passed as the parameter, the insn will be not chosen to be
 229        issued.  */
 230     int (* first_cycle_multipass_dfa_lookahead_guard) (rtx);
 231     /* The following member value is pointer to a function called by
 232        the insn scheduler before issuing insn passed as the third
 233        parameter on given cycle.  If the hook returns nonzero, the
 234        insn is not issued on given processors cycle.  Instead of that,
 235        the processor cycle is advanced.  If the value passed through
 236        the last parameter is zero, the insn ready queue is not sorted
 237        on the new cycle start as usually.  The first parameter passes
 238        file for debugging output.  The second one passes the scheduler
 239        verbose level of the debugging output.  The forth and the fifth
 240        parameter values are correspondingly processor cycle on which
 241        the previous insn has been issued and the current processor
 242        cycle.  */
 243     int (* dfa_new_cycle) (FILE *, int, rtx, int, int, int *);
 244     /* The values of the following members are pointers to functions
 245        used to improve the first cycle multipass scheduling by
 246        inserting nop insns.  dfa_scheduler_bubble gives a function
 247        returning a nop insn with given index.  The indexes start with
 248        zero.  The function should return NULL if there are no more nop
 249        insns with indexes greater than given index.  To initialize the
 250        nop insn the function given by member
 251        init_dfa_scheduler_bubbles is used.  The default values of the
 252        members result in not inserting nop insns during the multipass
 253        scheduling.  */
 254     void (* init_dfa_bubbles) (void);
 255     rtx (* dfa_bubble) (int);
 256     /* The following member value is a pointer to a function called
 257        by the insn scheduler.  It should return true if there exists a
 258        dependence which is considered costly by the target, between
 259        the insn passed as the first parameter, and the insn passed as
 260        the second parameter.  The third parameter is the INSN_DEPEND
 261        link that represents the dependence between the two insns.  The
 262        fourth argument is the cost of the dependence as estimated by
 263        the scheduler.  The last argument is the distance in cycles
 264        between the already scheduled insn (first parameter) and the
 265        the second insn (second parameter).  */
 266     bool (* is_costly_dependence) (rtx, rtx, rtx, int, int);
 267   } sched;
 268
 269   /* Given two decls, merge their attributes and return the result.  */
 270   tree (* merge_decl_attributes) (tree, tree);
 271
 272   /* Given two types, merge their attributes and return the result.  */
 273   tree (* merge_type_attributes) (tree, tree);
 274
 275   /* Table of machine attributes and functions to handle them.
 276      Ignored if NULL.  */
 277   const struct attribute_spec *attribute_table;
 278
 279   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 280      one if they are compatible and two if they are nearly compatible
 281      (which causes a warning to be generated).  */
 282   int (* comp_type_attributes) (tree type1, tree type2);
 283
 284   /* Assign default attributes to the newly defined TYPE.  */
 285   void (* set_default_type_attributes) (tree type);
 286
 287   /* Insert attributes on the newly created DECL.  */
 288   void (* insert_attributes) (tree decl, tree *attributes);
 289
 290   /* Return true if FNDECL (which has at least one machine attribute)
 291      can be inlined despite its machine attributes, false otherwise.  */
 292   bool (* function_attribute_inlinable_p) (tree fndecl);
 293
 294   /* Return true if bitfields in RECORD_TYPE should follow the
 295      Microsoft Visual C++ bitfield layout rules.  */
 296   bool (* ms_bitfield_layout_p) (tree record_type);
 297
 298   /* Set up target-specific built-in functions.  */
 299   void (* init_builtins) (void);
 300
 301   /* Expand a target-specific builtin.  */
 302   rtx (* expand_builtin) (tree exp, rtx target, rtx subtarget,
 303                           enum machine_mode mode, int ignore);
 304
 305   /* Make any adjustments to libfunc names needed for this target.  */
 306   void (* init_libfuncs) (void);
 307
 308   /* Given a decl, a section name, and whether the decl initializer
 309      has relocs, choose attributes for the section.  */
 310   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 311   unsigned int (* section_type_flags) (tree, const char *, int);
 312
 313   /* True if new jumps cannot be created, to replace existing ones or
 314      not, at the current point in the compilation.  */
 315   bool (* cannot_modify_jumps_p) (void);
 316
 317   /* Return a register class for which branch target register
 318      optimizations should be applied.  */
 319   int (* branch_target_register_class) (void);
 320
 321   /* Return true if branch target register optimizations should include
 322      callee-saved registers that are not already live during the current
 323      function.  AFTER_PE_GEN is true if prologues and epilogues have
 324      already been generated.  */
 325   bool (* branch_target_register_callee_saved) (bool after_pe_gen);
 326
 327   /* True if the constant X cannot be placed in the constant pool.  */
 328   bool (* cannot_force_const_mem) (rtx);
 329
 330   /* True if the insn X cannot be duplicated.  */
 331   bool (* cannot_copy_insn_p) (rtx);
 332
 333   /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS.  */
 334   rtx (* delegitimize_address) (rtx);
 335
 336   /* True if it is OK to do sibling call optimization for the specified
 337      call expression EXP.  DECL will be the called function, or NULL if
 338      this is an indirect call.  */
 339   bool (*function_ok_for_sibcall) (tree decl, tree exp);
 340
 341   /* True if EXP should be placed in a "small data" section.  */
 342   bool (* in_small_data_p) (tree);
 343
 344   /* True if EXP names an object for which name resolution must resolve
 345      to the current module.  */
 346   bool (* binds_local_p) (tree);
 347
 348   /* Do something target-specific to record properties of the DECL into
 349      the associated SYMBOL_REF.  */
 350   void (* encode_section_info) (tree, rtx, int);
 351
 352   /* Undo the effects of encode_section_info on the symbol string.  */
 353   const char * (* strip_name_encoding) (const char *);
 354
 355   /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))).  */
 356   bool (* valid_pointer_mode) (enum machine_mode mode);
 357
 358   /* True if a vector is opaque.  */
 359   bool (* vector_opaque_p) (tree);
 360
 361   /* Compute a (partial) cost for rtx X.  Return true if the complete
 362      cost has been computed, and false if subexpressions should be
 363      scanned.  In either case, *TOTAL contains the cost result.  */
 364   /* Note that CODE and OUTER_CODE ought to be RTX_CODE, but that's
 365      not necessarily defined at this point.  */
 366   bool (* rtx_costs) (rtx x, int code, int outer_code, int *total);
 367
 368   /* Compute the cost of X, used as an address.  Never called with
 369      invalid addresses.  */
 370   int (* address_cost) (rtx x);
 371
 372   /* Given a register, this hook should return a parallel of registers
 373      to represent where to find the register pieces.  Define this hook
 374      if the register and its mode are represented in Dwarf in
 375      non-contiguous locations, or if the register should be
 376      represented in more than one register in Dwarf.  Otherwise, this
 377      hook should return NULL_RTX.  */
 378   rtx (* dwarf_register_span) (rtx);
 379
 380   /* Do machine-dependent code transformations.  Called just before
 381      delayed-branch scheduling.  */
 382   void (* machine_dependent_reorg) (void);
 383
 384   /* Create the __builtin_va_list type.  */
 385   tree (* build_builtin_va_list) (void);
 386
 387   /* Validity-checking routines for PCH files, target-specific.
 388      get_pch_validity returns a pointer to the data to be stored,
 389      and stores the size in its argument.  pch_valid_p gets the same
 390      information back and returns NULL if the PCH is valid,
 391      or an error message if not.
 392   */
 393   void * (* get_pch_validity) (size_t *);
 394   const char * (* pch_valid_p) (const void *, size_t);
 395
 396   /* Leave the boolean fields at the end.  */
 397
 398   /* True if arbitrary sections are supported.  */
 399   bool have_named_sections;
 400
 401   /* True if "native" constructors and destructors are supported,
 402      false if we're using collect2 for the job.  */
 403   bool have_ctors_dtors;
 404
 405   /* True if thread-local storage is supported.  */
 406   bool have_tls;
 407
 408   /* True if a small readonly data section is supported.  */
 409   bool have_srodata_section;
 410
 411   /* True if EH frame info sections should be zero-terminated.  */
 412   bool terminate_dw2_eh_frame_info;
 413
 414   /* True if #NO_APP should be emitted at the beginning of
 415      assembly output.  */
 416   bool file_start_app_off;
 417
 418   /* True if output_file_directive should be called for main_input_filename
 419      at the beginning of assembly output.  */
 420   bool file_start_file_directive;
 421
 422   /* Functions relating to calls - argument passing, returns, etc.  */
 423   struct calls {
 424     bool (*promote_function_args) (tree fntype);
 425     bool (*promote_function_return) (tree fntype);
 426     bool (*promote_prototypes) (tree fntype);
 427     rtx (*struct_value_rtx) (tree fndecl, int incoming);
 428     bool (*return_in_memory) (tree type, tree fndecl);
 429     bool (*return_in_msb) (tree type);
 430     rtx (*expand_builtin_saveregs) (void);
 431     /* Returns pretend_argument_size.  */
 432     void (*setup_incoming_varargs) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 433                                     tree type, int *pretend_arg_size, int second_time);
 434     bool (*strict_argument_naming) (CUMULATIVE_ARGS *ca);
 435     /* Returns true if we should use SETUP_INCOMING_VARARGS and/or
 436        STRICT_ARGUMENT_NAMING.  */
 437     bool (*pretend_outgoing_varargs_named) (CUMULATIVE_ARGS *ca);
 438   } calls;
 439 };
 440
 441 extern struct gcc_target targetm;