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) (rtx x, unsigned int size, int aligned_p);
  71
  72     /* Output code that will globalize a label.  */
  73     void (* globalize_label) (FILE *, const char *);
  74
  75     /* Output an internal label.  */
  76     void (* internal_label) (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) (tree, int);
  81
  82     /* Output the assembler code for entry to a function.  */
  83     void (* function_prologue) (FILE *, HOST_WIDE_INT);
  84
  85     /* Output the assembler code for end of prologue.  */
  86     void (* function_end_prologue) (FILE *);
  87
  88     /* Output the assembler code for start of epilogue.  */
  89     void (* function_begin_epilogue) (FILE *);
  90
  91     /* Output the assembler code for function exit.  */
  92     void (* function_epilogue) (FILE *, HOST_WIDE_INT);
  93
  94     /* Switch to an arbitrary section NAME with attributes as
  95        specified by FLAGS.  */
  96     void (* named_section) (const char *, unsigned int);
  97
  98     /* Switch to the section that holds the exception table.  */
  99     void (* exception_section) (void);
 100
 101     /* Switch to the section that holds the exception frames.  */
 102     void (* eh_frame_section) (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) (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) (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) (tree, int);
 118
 119     /* Output a constructor for a symbol with a given priority.  */
 120     void (* constructor) (rtx, int);
 121
 122     /* Output a destructor for a symbol with a given priority.  */
 123     void (* destructor) (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) (FILE *file, tree thunk_decl,
 131                               HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset,
 132                               tree function_decl);
 133
 134     /* Determine whether output_mi_thunk would succeed.  */
 135     /* ??? Ideally, this hook would not exist, and success or failure
 136        would be returned from output_mi_thunk directly.  But there's
 137        too much undo-able setup involved in invoking output_mi_thunk.
 138        Could be fixed by making output_mi_thunk emit rtl instead of
 139        text to the output file.  */
 140     bool (* can_output_mi_thunk) (tree thunk_decl, HOST_WIDE_INT delta,
 141                                   HOST_WIDE_INT vcall_offset,
 142                                   tree function_decl);
 143
 144     /* Output any boilerplate text needed at the beginning of a
 145        translation unit.  */
 146     void (*file_start) (void);
 147
 148     /* Output any boilerplate text needed at the end of a
 149        translation unit.  */
 150     void (*file_end) (void);
 151   } asm_out;
 152
 153   /* Functions relating to instruction scheduling.  */
 154   struct sched
 155   {
 156     /* Given the current cost, COST, of an insn, INSN, calculate and
 157        return a new cost based on its relationship to DEP_INSN through
 158        the dependence LINK.  The default is to make no adjustment.  */
 159     int (* adjust_cost) (rtx insn, rtx link, rtx def_insn, int cost);
 160
 161     /* Adjust the priority of an insn as you see fit.  Returns the new
 162        priority.  */
 163     int (* adjust_priority) (rtx, int);
 164
 165     /* Function which returns the maximum number of insns that can be
 166        scheduled in the same machine cycle.  This must be constant
 167        over an entire compilation.  The default is 1.  */
 168     int (* issue_rate) (void);
 169
 170     /* Calculate how much this insn affects how many more insns we
 171        can emit this cycle.  Default is they all cost the same.  */
 172     int (* variable_issue) (FILE *, int, rtx, int);
 173
 174     /* Initialize machine-dependent scheduling code.  */
 175     void (* md_init) (FILE *, int, int);
 176
 177     /* Finalize machine-dependent scheduling code.  */
 178     void (* md_finish) (FILE *, int);
 179
 180     /* Reorder insns in a machine-dependent fashion, in two different
 181        places.  Default does nothing.  */
 182     int (* reorder) (FILE *, int, rtx *, int *, int);
 183     int (* reorder2) (FILE *, int, rtx *, int *, int);
 184
 185     /* The following member value is a pointer to a function called
 186        after evaluation forward dependencies of insns in chain given
 187        by two parameter values (head and tail correspondingly).  */
 188     void (* dependencies_evaluation_hook) (rtx, rtx);
 189
 190     /* The following member value is a pointer to a function returning
 191        nonzero if we should use DFA based scheduling.  The default is
 192        to use the old pipeline scheduler.  */
 193     int (* use_dfa_pipeline_interface) (void);
 194     /* The values of all the following members are used only for the
 195        DFA based scheduler: */
 196     /* The values of the following four members are pointers to
 197        functions used to simplify the automaton descriptions.
 198        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 199        returning insns which are used to change the pipeline hazard
 200        recognizer state when the new simulated processor cycle
 201        correspondingly starts and finishes.  The function defined by
 202        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 203        to initialize the corresponding insns.  The default values of
 204        the memebers result in not changing the automaton state when
 205        the new simulated processor cycle correspondingly starts and
 206        finishes.  */
 207     void (* init_dfa_pre_cycle_insn) (void);
 208     rtx (* dfa_pre_cycle_insn) (void);
 209     void (* init_dfa_post_cycle_insn) (void);
 210     rtx (* dfa_post_cycle_insn) (void);
 211     /* The following member value is a pointer to a function returning value
 212        which defines how many insns in queue `ready' will we try for
 213        multi-pass scheduling.  if the member value is nonzero and the
 214        function returns positive value, the DFA based scheduler will make
 215        multi-pass scheduling for the first cycle.  In other words, we will
 216        try to choose ready insn which permits to start maximum number of
 217        insns on the same cycle.  */
 218     int (* first_cycle_multipass_dfa_lookahead) (void);
 219     /* The following member value is pointer to a function controlling
 220        what insns from the ready insn queue will be considered for the
 221        multipass insn scheduling.  If the hook returns zero for insn
 222        passed as the parameter, the insn will be not chosen to be
 223        issued.  */
 224     int (* first_cycle_multipass_dfa_lookahead_guard) (rtx);
 225     /* The following member value is pointer to a function called by
 226        the insn scheduler before issuing insn passed as the third
 227        parameter on given cycle.  If the hook returns nonzero, the
 228        insn is not issued on given processors cycle.  Instead of that,
 229        the processor cycle is advanced.  If the value passed through
 230        the last parameter is zero, the insn ready queue is not sorted
 231        on the new cycle start as usually.  The first parameter passes
 232        file for debugging output.  The second one passes the scheduler
 233        verbose level of the debugging output.  The forth and the fifth
 234        parameter values are correspondingly processor cycle on which
 235        the previous insn has been issued and the current processor
 236        cycle.  */
 237     int (* dfa_new_cycle) (FILE *, int, rtx, int, int, int *);
 238     /* The values of the following members are pointers to functions
 239        used to improve the first cycle multipass scheduling by
 240        inserting nop insns.  dfa_scheduler_bubble gives a function
 241        returning a nop insn with given index.  The indexes start with
 242        zero.  The function should return NULL if there are no more nop
 243        insns with indexes greater than given index.  To initialize the
 244        nop insn the function given by member
 245        init_dfa_scheduler_bubbles is used.  The default values of the
 246        members result in not inserting nop insns during the multipass
 247        scheduling.  */
 248     void (* init_dfa_bubbles) (void);
 249     rtx (* dfa_bubble) (int);
 250   } sched;
 251
 252   /* Given two decls, merge their attributes and return the result.  */
 253   tree (* merge_decl_attributes) (tree, tree);
 254
 255   /* Given two types, merge their attributes and return the result.  */
 256   tree (* merge_type_attributes) (tree, tree);
 257
 258   /* Table of machine attributes and functions to handle them.
 259      Ignored if NULL.  */
 260   const struct attribute_spec *attribute_table;
 261
 262   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 263      one if they are compatible and two if they are nearly compatible
 264      (which causes a warning to be generated).  */
 265   int (* comp_type_attributes) (tree type1, tree type2);
 266
 267   /* Assign default attributes to the newly defined TYPE.  */
 268   void (* set_default_type_attributes) (tree type);
 269
 270   /* Insert attributes on the newly created DECL.  */
 271   void (* insert_attributes) (tree decl, tree *attributes);
 272
 273   /* Return true if FNDECL (which has at least one machine attribute)
 274      can be inlined despite its machine attributes, false otherwise.  */
 275   bool (* function_attribute_inlinable_p) (tree fndecl);
 276
 277   /* Return true if bitfields in RECORD_TYPE should follow the
 278      Microsoft Visual C++ bitfield layout rules.  */
 279   bool (* ms_bitfield_layout_p) (tree record_type);
 280
 281   /* Set up target-specific built-in functions.  */
 282   void (* init_builtins) (void);
 283
 284   /* Expand a target-specific builtin.  */
 285   rtx (* expand_builtin) (tree exp, rtx target, rtx subtarget,
 286                           enum machine_mode mode, int ignore);
 287
 288   /* Given a decl, a section name, and whether the decl initializer
 289      has relocs, choose attributes for the section.  */
 290   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 291   unsigned int (* section_type_flags) (tree, const char *, int);
 292
 293   /* True if new jumps cannot be created, to replace existing ones or
 294      not, at the current point in the compilation.  */
 295   bool (* cannot_modify_jumps_p) (void);
 296
 297   /* Return a register class for which branch target register
 298      optimizations should be applied.  */
 299   int (* branch_target_register_class) (void);
 300
 301   /* Return true if branch target register optimizations should include
 302      callee-saved registers that are not already live during the current
 303      function.  AFTER_PE_GEN is true if prologues and epilogues have
 304      already been generated.  */
 305   bool (* branch_target_register_callee_saved) (bool after_pe_gen);
 306
 307   /* True if the constant X cannot be placed in the constant pool.  */
 308   bool (* cannot_force_const_mem) (rtx);
 309
 310   /* True if the insn X cannot be duplicated.  */
 311   bool (* cannot_copy_insn_p) (rtx);
 312
 313   /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS.  */
 314   rtx (* delegitimize_address) (rtx);
 315
 316   /* True if it is OK to do sibling call optimization for the specified
 317      call expression EXP.  DECL will be the called function, or NULL if
 318      this is an indirect call.  */
 319   bool (*function_ok_for_sibcall) (tree decl, tree exp);
 320
 321   /* True if EXP should be placed in a "small data" section.  */
 322   bool (* in_small_data_p) (tree);
 323
 324   /* True if EXP names an object for which name resolution must resolve
 325      to the current module.  */
 326   bool (* binds_local_p) (tree);
 327
 328   /* Do something target-specific to record properties of the DECL into
 329      the associated SYMBOL_REF.  */
 330   void (* encode_section_info) (tree, rtx, int);
 331
 332   /* Undo the effects of encode_section_info on the symbol string.  */
 333   const char * (* strip_name_encoding) (const char *);
 334
 335   /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))).  */
 336   bool (* valid_pointer_mode) (enum machine_mode mode);
 337
 338   /* True if a vector is opaque.  */
 339   bool (* vector_opaque_p) (tree);
 340
 341   /* Compute a (partial) cost for rtx X.  Return true if the complete
 342      cost has been computed, and false if subexpressions should be
 343      scanned.  In either case, *TOTAL contains the cost result.  */
 344   /* Note that CODE and OUTER_CODE ought to be RTX_CODE, but that's
 345      not necessarily defined at this point.  */
 346   bool (* rtx_costs) (rtx x, int code, int outer_code, int *total);
 347
 348   /* Compute the cost of X, used as an address.  Never called with
 349      invalid addresses.  */
 350   int (* address_cost) (rtx x);
 351
 352   /* Given a register, this hook should return a parallel of registers
 353      to represent where to find the register pieces.  Define this hook
 354      if the register and its mode are represented in Dwarf in
 355      non-contiguous locations, or if the register should be
 356      represented in more than one register in Dwarf.  Otherwise, this
 357      hook should return NULL_RTX.  */
 358   rtx (* dwarf_register_span) (rtx);
 359
 360   /* Do machine-dependent code transformations.  Called just before
 361      delayed-branch scheduling.  */
 362   void (* machine_dependent_reorg) (void);
 363
 364   /* Leave the boolean fields at the end.  */
 365
 366   /* True if arbitrary sections are supported.  */
 367   bool have_named_sections;
 368
 369   /* True if "native" constructors and destructors are supported,
 370      false if we're using collect2 for the job.  */
 371   bool have_ctors_dtors;
 372
 373   /* True if thread-local storage is supported.  */
 374   bool have_tls;
 375
 376   /* True if a small readonly data section is supported.  */
 377   bool have_srodata_section;
 378
 379   /* True if EH frame info sections should be zero-terminated.  */
 380   bool terminate_dw2_eh_frame_info;
 381
 382   /* True if #NO_APP should be emitted at the beginning of
 383      assembly output.  */
 384   bool file_start_app_off;
 385
 386   /* True if output_file_directive should be called for main_input_filename
 387      at the beginning of assembly output.  */
 388   bool file_start_file_directive;
 389 };
 390
 391 extern struct gcc_target targetm;