gcc/target.h

   1 /* Data structure definitions for a generic GCC target.
   2    Copyright (C) 2001, 2002 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 for which TREE_CST_RTL is valid.  RELOC is nonzero if
 106        runtime relocations must be applied; bit 1 will be set if the
 107        runtime relocations require non-local name resolution.  ALIGN is
 108        the required alignment of the data.  */
 109     void (* select_section) PARAMS ((tree, int, unsigned HOST_WIDE_INT));
 110
 111     /* Select and switch to a section for X with MODE.  ALIGN is
 112        the desired alignment of the data.  */
 113     void (* select_rtx_section) PARAMS ((enum machine_mode, rtx,
 114                                          unsigned HOST_WIDE_INT));
 115
 116     /* Select a unique section name for DECL.  RELOC is the same as
 117        for SELECT_SECTION.  */
 118     void (* unique_section) PARAMS ((tree, int));
 119
 120     /* Output a constructor for a symbol with a given priority.  */
 121     void (* constructor) PARAMS ((rtx, int));
 122
 123     /* Output a destructor for a symbol with a given priority.  */
 124     void (* destructor) PARAMS ((rtx, int));
 125
 126     /* Output the assembler code for a thunk function.  THUNK_DECL is the
 127        declaration for the thunk function itself, FUNCTION is the decl for
 128        the target function.  DELTA is an immediate constant offset to be
 129        added to THIS.  If VCALL_OFFSET is nonzero, the word at
 130        *(*this + vcall_offset) should be added to THIS.  */
 131     void (* output_mi_thunk) PARAMS ((FILE *file, tree thunk_decl,
 132                                       HOST_WIDE_INT delta,
 133                                       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) PARAMS ((tree thunk_decl,
 143                                           HOST_WIDE_INT delta,
 144                                           HOST_WIDE_INT vcall_offset,
 145                                           tree function_decl));
 146   } asm_out;
 147
 148   /* Functions relating to instruction scheduling.  */
 149   struct sched
 150   {
 151     /* Given the current cost, COST, of an insn, INSN, calculate and
 152        return a new cost based on its relationship to DEP_INSN through
 153        the dependence LINK.  The default is to make no adjustment.  */
 154     int (* adjust_cost) PARAMS ((rtx insn, rtx link, rtx def_insn, int cost));
 155
 156     /* Adjust the priority of an insn as you see fit.  Returns the new
 157        priority.  */
 158     int (* adjust_priority) PARAMS ((rtx, int));
 159
 160     /* Function which returns the maximum number of insns that can be
 161        scheduled in the same machine cycle.  This must be constant
 162        over an entire compilation.  The default is 1.  */
 163     int (* issue_rate) PARAMS ((void));
 164
 165     /* Calculate how much this insn affects how many more insns we
 166        can emit this cycle.  Default is they all cost the same.  */
 167     int (* variable_issue) PARAMS ((FILE *, int, rtx, int));
 168
 169     /* Initialize machine-dependent scheduling code.  */
 170     void (* md_init) PARAMS ((FILE *, int, int));
 171
 172     /* Finalize machine-dependent scheduling code.  */
 173     void (* md_finish) PARAMS ((FILE *, int));
 174
 175     /* Reorder insns in a machine-dependent fashion, in two different
 176        places.  Default does nothing.  */
 177     int (* reorder)  PARAMS ((FILE *, int, rtx *, int *, int));
 178     int (* reorder2) PARAMS ((FILE *, int, rtx *, int *, int));
 179
 180     /* The following member value is a pointer to a function called
 181        after evaluation forward dependencies of insns in chain given
 182        by two parameter values (head and tail correspondingly).  */
 183     void (* dependencies_evaluation_hook) PARAMS ((rtx, rtx));
 184
 185     /* The following member value is a pointer to a function returning
 186        nonzero if we should use DFA based scheduling.  The default is
 187        to use the old pipeline scheduler.  */
 188     int (* use_dfa_pipeline_interface) PARAMS ((void));
 189     /* The values of all the following members are used only for the
 190        DFA based scheduler: */
 191     /* The values of the following four members are pointers to
 192        functions used to simplify the automaton descriptions.
 193        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 194        returning insns which are used to change the pipeline hazard
 195        recognizer state when the new simulated processor cycle
 196        correspondingly starts and finishes.  The function defined by
 197        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 198        to initialize the corresponding insns.  The default values of
 199        the memebers result in not changing the automaton state when
 200        the new simulated processor cycle correspondingly starts and
 201        finishes.  */
 202     void (* init_dfa_pre_cycle_insn) PARAMS ((void));
 203     rtx (* dfa_pre_cycle_insn) PARAMS ((void));
 204     void (* init_dfa_post_cycle_insn) PARAMS ((void));
 205     rtx (* dfa_post_cycle_insn) PARAMS ((void));
 206     /* The following member value is a pointer to a function returning value
 207        which defines how many insns in queue `ready' will we try for
 208        multi-pass scheduling.  if the member value is nonzero and the
 209        function returns positive value, the DFA based scheduler will make
 210        multi-pass scheduling for the first cycle.  In other words, we will
 211        try to choose ready insn which permits to start maximum number of
 212        insns on the same cycle.  */
 213     int (* first_cycle_multipass_dfa_lookahead) PARAMS ((void));
 214     /* The following member value is pointer to a function controlling
 215        what insns from the ready insn queue will be considered for the
 216        multipass insn scheduling.  If the hook returns zero for insn
 217        passed as the parameter, the insn will be not chosen to be
 218        issued.  */
 219     int (* first_cycle_multipass_dfa_lookahead_guard) PARAMS ((rtx));
 220     /* The following member value is pointer to a function called by
 221        the insn scheduler before issuing insn passed as the third
 222        parameter on given cycle.  If the hook returns nonzero, the
 223        insn is not issued on given processors cycle.  Instead of that,
 224        the processor cycle is advanced.  If the value passed through
 225        the last parameter is zero, the insn ready queue is not sorted
 226        on the new cycle start as usually.  The first parameter passes
 227        file for debugging output.  The second one passes the scheduler
 228        verbose level of the debugging output.  The forth and the fifth
 229        parameter values are correspondingly processor cycle on which
 230        the previous insn has been issued and the current processor
 231        cycle.  */
 232     int (* dfa_new_cycle) PARAMS ((FILE *, int, rtx, int, int, int *));
 233     /* The values of the following members are pointers to functions
 234        used to improve the first cycle multipass scheduling by
 235        inserting nop insns.  dfa_scheduler_bubble gives a function
 236        returning a nop insn with given index.  The indexes start with
 237        zero.  The function should return NULL if there are no more nop
 238        insns with indexes greater than given index.  To initialize the
 239        nop insn the function given by member
 240        init_dfa_scheduler_bubbles is used.  The default values of the
 241        members result in not inserting nop insns during the multipass
 242        scheduling.  */
 243     void (* init_dfa_bubbles) PARAMS ((void));
 244     rtx (* dfa_bubble) PARAMS ((int));
 245   } sched;
 246
 247   /* Given two decls, merge their attributes and return the result.  */
 248   tree (* merge_decl_attributes) PARAMS ((tree, tree));
 249
 250   /* Given two types, merge their attributes and return the result.  */
 251   tree (* merge_type_attributes) PARAMS ((tree, tree));
 252
 253   /* Table of machine attributes and functions to handle them.
 254      Ignored if NULL.  */
 255   const struct attribute_spec *attribute_table;
 256
 257   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 258      one if they are compatible and two if they are nearly compatible
 259      (which causes a warning to be generated).  */
 260   int (* comp_type_attributes) PARAMS ((tree type1, tree type2));
 261
 262   /* Assign default attributes to the newly defined TYPE.  */
 263   void (* set_default_type_attributes) PARAMS ((tree type));
 264
 265   /* Insert attributes on the newly created DECL.  */
 266   void (* insert_attributes) PARAMS ((tree decl, tree *attributes));
 267
 268   /* Return true if FNDECL (which has at least one machine attribute)
 269      can be inlined despite its machine attributes, false otherwise.  */
 270   bool (* function_attribute_inlinable_p) PARAMS ((tree fndecl));
 271
 272   /* Return true if bitfields in RECORD_TYPE should follow the
 273      Microsoft Visual C++ bitfield layout rules.  */
 274   bool (* ms_bitfield_layout_p) PARAMS ((tree record_type));
 275
 276   /* Set up target-specific built-in functions.  */
 277   void (* init_builtins) PARAMS ((void));
 278
 279   /* Expand a target-specific builtin.  */
 280   rtx (* expand_builtin) PARAMS ((tree exp, rtx target, rtx subtarget,
 281                                   enum machine_mode mode, int ignore));
 282
 283   /* Given a decl, a section name, and whether the decl initializer
 284      has relocs, choose attributes for the section.  */
 285   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 286   unsigned int (* section_type_flags) PARAMS ((tree, const char *, int));
 287
 288   /* True if new jumps cannot be created, to replace existing ones or
 289      not, at the current point in the compilation.  */
 290   bool (* cannot_modify_jumps_p) PARAMS ((void));
 291
 292   /* True if the constant X cannot be placed in the constant pool.  */
 293   bool (* cannot_force_const_mem) PARAMS ((rtx));
 294
 295   /* True if it is OK to do sibling call optimization for the specified
 296      call expression EXP.  DECL will be the called function, or NULL if
 297      this is an indirect call.  */
 298   bool (*function_ok_for_sibcall) PARAMS ((tree decl, tree exp));
 299
 300   /* True if EXP should be placed in a "small data" section.  */
 301   bool (* in_small_data_p) PARAMS ((tree));
 302
 303   /* True if EXP names an object for which name resolution must resolve
 304      to the current module.  */
 305   bool (* binds_local_p) PARAMS ((tree));
 306
 307   /* Do something target-specific to record properties of the DECL into
 308      the associated SYMBOL_REF.  */
 309   void (* encode_section_info) PARAMS ((tree, int));
 310
 311   /* Undo the effects of encode_section_info on the symbol string.  */
 312   const char * (* strip_name_encoding) PARAMS ((const char *));
 313
 314   bool (* valid_pointer_mode) PARAMS ((enum machine_mode mode));
 315   /* Leave the boolean fields at the end.  */
 316
 317   /* True if arbitrary sections are supported.  */
 318   bool have_named_sections;
 319
 320   /* True if "native" constructors and destructors are supported,
 321      false if we're using collect2 for the job.  */
 322   bool have_ctors_dtors;
 323
 324   /* True if thread-local storage is supported.  */
 325   bool have_tls;
 326
 327   /* True if a small readonly data section is supported.  */
 328   bool have_srodata_section;
 329
 330   /* True if EH frame info sections should be zero-terminated.  */
 331   bool terminate_dw2_eh_frame_info;
 332 };
 333
 334 extern struct gcc_target targetm;