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