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     /* Emit an assembler directive to set visibility for the symbol
  76        associated with the tree decl.  */
  77     void (* visibility) PARAMS ((tree, int));
  78
  79     /* Output the assembler code for entry to a function.  */
  80     void (* function_prologue) PARAMS ((FILE *, HOST_WIDE_INT));
  81
  82     /* Output the assembler code for end of prologue.  */
  83     void (* function_end_prologue) PARAMS ((FILE *));
  84
  85     /* Output the assembler code for start of epilogue.  */
  86     void (* function_begin_epilogue) PARAMS ((FILE *));
  87
  88     /* Output the assembler code for function exit.  */
  89     void (* function_epilogue) PARAMS ((FILE *, HOST_WIDE_INT));
  90
  91     /* Switch to an arbitrary section NAME with attributes as
  92        specified by FLAGS.  */
  93     void (* named_section) PARAMS ((const char *, unsigned int));
  94
  95     /* Switch to the section that holds the exception table.  */
  96     void (* exception_section) PARAMS ((void));
  97
  98     /* Switch to the section that holds the exception frames.  */
  99     void (* eh_frame_section) PARAMS ((void));
 100
 101     /* Select and switch to a section for EXP.  It may be a DECL or a
 102        constant for which TREE_CST_RTL is valid.  RELOC is nonzero if
 103        runtime relocations must be applied; bit 1 will be set if the
 104        runtime relocations require non-local name resolution.  ALIGN is
 105        the required alignment of the data.  */
 106     void (* select_section) PARAMS ((tree, int, unsigned HOST_WIDE_INT));
 107
 108     /* Select and switch to a section for X with MODE.  ALIGN is
 109        the desired alignment of the data.  */
 110     void (* select_rtx_section) PARAMS ((enum machine_mode, rtx,
 111                                          unsigned HOST_WIDE_INT));
 112
 113     /* Select a unique section name for DECL.  RELOC is the same as
 114        for SELECT_SECTION.  */
 115     void (* unique_section) PARAMS ((tree, int));
 116
 117     /* Output a constructor for a symbol with a given priority.  */
 118     void (* constructor) PARAMS ((rtx, int));
 119
 120     /* Output a destructor for a symbol with a given priority.  */
 121     void (* destructor) PARAMS ((rtx, int));
 122
 123     /* Output the assembler code for a thunk function.  THUNK_DECL is the
 124        declaration for the thunk function itself, FUNCTION is the decl for
 125        the target function.  DELTA is an immediate constant offset to be
 126        added to THIS.  If VCALL_OFFSET is nonzero, the word at
 127        *(*this + vcall_offset) should be added to THIS.  */
 128     void (* output_mi_thunk) PARAMS ((FILE *file, tree thunk_decl,
 129                                       HOST_WIDE_INT delta,
 130                                       HOST_WIDE_INT vcall_offset,
 131                                       tree function_decl));
 132
 133     /* Determine whether output_mi_thunk would succeed.  */
 134     /* ??? Ideally, this hook would not exist, and success or failure
 135        would be returned from output_mi_thunk directly.  But there's
 136        too much undo-able setup involved in invoking output_mi_thunk.
 137        Could be fixed by making output_mi_thunk emit rtl instead of
 138        text to the output file.  */
 139     bool (* can_output_mi_thunk) PARAMS ((tree thunk_decl,
 140                                           HOST_WIDE_INT delta,
 141                                           HOST_WIDE_INT vcall_offset,
 142                                           tree function_decl));
 143   } asm_out;
 144
 145   /* Functions relating to instruction scheduling.  */
 146   struct sched
 147   {
 148     /* Given the current cost, COST, of an insn, INSN, calculate and
 149        return a new cost based on its relationship to DEP_INSN through
 150        the dependence LINK.  The default is to make no adjustment.  */
 151     int (* adjust_cost) PARAMS ((rtx insn, rtx link, rtx def_insn, int cost));
 152
 153     /* Adjust the priority of an insn as you see fit.  Returns the new
 154        priority.  */
 155     int (* adjust_priority) PARAMS ((rtx, int));
 156
 157     /* Function which returns the maximum number of insns that can be
 158        scheduled in the same machine cycle.  This must be constant
 159        over an entire compilation.  The default is 1.  */
 160     int (* issue_rate) PARAMS ((void));
 161
 162     /* Calculate how much this insn affects how many more insns we
 163        can emit this cycle.  Default is they all cost the same.  */
 164     int (* variable_issue) PARAMS ((FILE *, int, rtx, int));
 165
 166     /* Initialize machine-dependent scheduling code.  */
 167     void (* md_init) PARAMS ((FILE *, int, int));
 168
 169     /* Finalize machine-dependent scheduling code.  */
 170     void (* md_finish) PARAMS ((FILE *, int));
 171
 172     /* Reorder insns in a machine-dependent fashion, in two different
 173        places.  Default does nothing.  */
 174     int (* reorder)  PARAMS ((FILE *, int, rtx *, int *, int));
 175     int (* reorder2) PARAMS ((FILE *, int, rtx *, int *, int));
 176
 177     /* The following member value is a pointer to a function returning
 178        nonzero if we should use DFA based scheduling.  The default is
 179        to use the old pipeline scheduler.  */
 180     int (* use_dfa_pipeline_interface) PARAMS ((void));
 181     /* The values of all the following members are used only for the
 182        DFA based scheduler: */
 183     /* The values of the following four members are pointers to
 184        functions used to simplify the automaton descriptions.
 185        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 186        returning insns which are used to change the pipeline hazard
 187        recognizer state when the new simulated processor cycle
 188        correspondingly starts and finishes.  The function defined by
 189        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 190        to initialize the corresponding insns.  The default values of
 191        the memebers result in not changing the automaton state when
 192        the new simulated processor cycle correspondingly starts and
 193        finishes.  */
 194     void (* init_dfa_pre_cycle_insn) PARAMS ((void));
 195     rtx (* dfa_pre_cycle_insn) PARAMS ((void));
 196     void (* init_dfa_post_cycle_insn) PARAMS ((void));
 197     rtx (* dfa_post_cycle_insn) PARAMS ((void));
 198     /* The following member value is a pointer to a function returning value
 199        which defines how many insns in queue `ready' will we try for
 200        multi-pass scheduling.  if the member value is nonzero and the
 201        function returns positive value, the DFA based scheduler will make
 202        multi-pass scheduling for the first cycle.  In other words, we will
 203        try to choose ready insn which permits to start maximum number of
 204        insns on the same cycle.  */
 205     int (* first_cycle_multipass_dfa_lookahead) PARAMS ((void));
 206     /* The values of the following members are pointers to functions
 207        used to improve the first cycle multipass scheduling by
 208        inserting nop insns.  dfa_scheduler_bubble gives a function
 209        returning a nop insn with given index.  The indexes start with
 210        zero.  The function should return NULL if there are no more nop
 211        insns with indexes greater than given index.  To initialize the
 212        nop insn the function given by member
 213        init_dfa_scheduler_bubbles is used.  The default values of the
 214        members result in not inserting nop insns during the multipass
 215        scheduling.  */
 216     void (* init_dfa_bubbles) PARAMS ((void));
 217     rtx (* dfa_bubble) PARAMS ((int));
 218   } sched;
 219
 220   /* Given two decls, merge their attributes and return the result.  */
 221   tree (* merge_decl_attributes) PARAMS ((tree, tree));
 222
 223   /* Given two types, merge their attributes and return the result.  */
 224   tree (* merge_type_attributes) PARAMS ((tree, tree));
 225
 226   /* Table of machine attributes and functions to handle them.
 227      Ignored if NULL.  */
 228   const struct attribute_spec *attribute_table;
 229
 230   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 231      one if they are compatible and two if they are nearly compatible
 232      (which causes a warning to be generated).  */
 233   int (* comp_type_attributes) PARAMS ((tree type1, tree type2));
 234
 235   /* Assign default attributes to the newly defined TYPE.  */
 236   void (* set_default_type_attributes) PARAMS ((tree type));
 237
 238   /* Insert attributes on the newly created DECL.  */
 239   void (* insert_attributes) PARAMS ((tree decl, tree *attributes));
 240
 241   /* Return true if FNDECL (which has at least one machine attribute)
 242      can be inlined despite its machine attributes, false otherwise.  */
 243   bool (* function_attribute_inlinable_p) PARAMS ((tree fndecl));
 244
 245   /* Return true if bitfields in RECORD_TYPE should follow the
 246      Microsoft Visual C++ bitfield layout rules.  */
 247   bool (* ms_bitfield_layout_p) PARAMS ((tree record_type));
 248
 249   /* Set up target-specific built-in functions.  */
 250   void (* init_builtins) PARAMS ((void));
 251
 252   /* Expand a target-specific builtin.  */
 253   rtx (* expand_builtin) PARAMS ((tree exp, rtx target, rtx subtarget,
 254                                   enum machine_mode mode, int ignore));
 255
 256   /* Given a decl, a section name, and whether the decl initializer
 257      has relocs, choose attributes for the section.  */
 258   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 259   unsigned int (* section_type_flags) PARAMS ((tree, const char *, int));
 260
 261   /* True if new jumps cannot be created, to replace existing ones or
 262      not, at the current point in the compilation.  */
 263   bool (* cannot_modify_jumps_p) PARAMS ((void));
 264
 265   /* True if the constant X cannot be placed in the constant pool.  */
 266   bool (* cannot_force_const_mem) PARAMS ((rtx));
 267
 268   /* True if EXP should be placed in a "small data" section.  */
 269   bool (* in_small_data_p) PARAMS ((tree));
 270
 271   /* True if EXP names an object for which name resolution must resolve
 272      to the current module.  */
 273   bool (* binds_local_p) PARAMS ((tree));
 274
 275   /* Do something target-specific to record properties of the DECL into
 276      the associated SYMBOL_REF.  */
 277   void (* encode_section_info) PARAMS ((tree, int));
 278
 279   /* Undo the effects of encode_section_info on the symbol string.  */
 280   const char * (* strip_name_encoding) PARAMS ((const char *));
 281
 282   /* Leave the boolean fields at the end.  */
 283
 284   /* True if arbitrary sections are supported.  */
 285   bool have_named_sections;
 286
 287   /* True if "native" constructors and destructors are supported,
 288      false if we're using collect2 for the job.  */
 289   bool have_ctors_dtors;
 290
 291   /* True if thread-local storage is supported.  */
 292   bool have_tls;
 293
 294   /* True if a small readonly data section is supported.  */
 295   bool have_srodata_section;
 296
 297   /* True if EH frame info sections should be zero-terminated.  */
 298   bool terminate_dw2_eh_frame_info;
 299 };
 300
 301 extern struct gcc_target targetm;