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