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