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, const char *));
  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   } asm_out;
 123
 124   /* Functions relating to instruction scheduling.  */
 125   struct sched
 126   {
 127     /* Given the current cost, COST, of an insn, INSN, calculate and
 128        return a new cost based on its relationship to DEP_INSN through
 129        the dependence LINK.  The default is to make no adjustment.  */
 130     int (* adjust_cost) PARAMS ((rtx insn, rtx link, rtx def_insn, int cost));
 131
 132     /* Adjust the priority of an insn as you see fit.  Returns the new
 133        priority.  */
 134     int (* adjust_priority) PARAMS ((rtx, int));
 135
 136     /* Function which returns the maximum number of insns that can be
 137        scheduled in the same machine cycle.  This must be constant
 138        over an entire compilation.  The default is 1.  */
 139     int (* issue_rate) PARAMS ((void));
 140
 141     /* Calculate how much this insn affects how many more insns we
 142        can emit this cycle.  Default is they all cost the same.  */
 143     int (* variable_issue) PARAMS ((FILE *, int, rtx, int));
 144
 145     /* Initialize machine-dependent scheduling code.  */
 146     void (* md_init) PARAMS ((FILE *, int, int));
 147
 148     /* Finalize machine-dependent scheduling code.  */
 149     void (* md_finish) PARAMS ((FILE *, int));
 150
 151     /* Reorder insns in a machine-dependent fashion, in two different
 152        places.  Default does nothing.  */
 153     int (* reorder)  PARAMS ((FILE *, int, rtx *, int *, int));
 154     int (* reorder2) PARAMS ((FILE *, int, rtx *, int *, int));
 155
 156     /* The following member value is a pointer to a function returning
 157        nonzero if we should use DFA based scheduling.  The default is
 158        to use the old pipeline scheduler.  */
 159     int (* use_dfa_pipeline_interface) PARAMS ((void));
 160     /* The values of all the following members are used only for the
 161        DFA based scheduler: */
 162     /* The values of the following four members are pointers to
 163        functions used to simplify the automaton descriptions.
 164        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 165        returning insns which are used to change the pipeline hazard
 166        recognizer state when the new simulated processor cycle
 167        correspondingly starts and finishes.  The function defined by
 168        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 169        to initialize the corresponding insns.  The default values of
 170        the memebers result in not changing the automaton state when
 171        the new simulated processor cycle correspondingly starts and
 172        finishes.  */
 173     void (* init_dfa_pre_cycle_insn) PARAMS ((void));
 174     rtx (* dfa_pre_cycle_insn) PARAMS ((void));
 175     void (* init_dfa_post_cycle_insn) PARAMS ((void));
 176     rtx (* dfa_post_cycle_insn) PARAMS ((void));
 177     /* The following member value is a pointer to a function returning value
 178        which defines how many insns in queue `ready' will we try for
 179        multi-pass scheduling.  if the member value is nonzero and the
 180        function returns positive value, the DFA based scheduler will make
 181        multi-pass scheduling for the first cycle.  In other words, we will
 182        try to choose ready insn which permits to start maximum number of
 183        insns on the same cycle.  */
 184     int (* first_cycle_multipass_dfa_lookahead) PARAMS ((void));
 185     /* The values of the following members are pointers to functions
 186        used to improve the first cycle multipass scheduling by
 187        inserting nop insns.  dfa_scheduler_bubble gives a function
 188        returning a nop insn with given index.  The indexes start with
 189        zero.  The function should return NULL if there are no more nop
 190        insns with indexes greater than given index.  To initialize the
 191        nop insn the function given by member
 192        init_dfa_scheduler_bubbles is used.  The default values of the
 193        members result in not inserting nop insns during the multipass
 194        scheduling.  */
 195     void (* init_dfa_bubbles) PARAMS ((void));
 196     rtx (* dfa_bubble) PARAMS ((int));
 197   } sched;
 198
 199   /* Given two decls, merge their attributes and return the result.  */
 200   tree (* merge_decl_attributes) PARAMS ((tree, tree));
 201
 202   /* Given two types, merge their attributes and return the result.  */
 203   tree (* merge_type_attributes) PARAMS ((tree, tree));
 204
 205   /* Table of machine attributes and functions to handle them.
 206      Ignored if NULL.  */
 207   const struct attribute_spec *attribute_table;
 208
 209   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 210      one if they are compatible and two if they are nearly compatible
 211      (which causes a warning to be generated).  */
 212   int (* comp_type_attributes) PARAMS ((tree type1, tree type2));
 213
 214   /* Assign default attributes to the newly defined TYPE.  */
 215   void (* set_default_type_attributes) PARAMS ((tree type));
 216
 217   /* Insert attributes on the newly created DECL.  */
 218   void (* insert_attributes) PARAMS ((tree decl, tree *attributes));
 219
 220   /* Return true if FNDECL (which has at least one machine attribute)
 221      can be inlined despite its machine attributes, false otherwise.  */
 222   bool (* function_attribute_inlinable_p) PARAMS ((tree fndecl));
 223
 224   /* Return true if bitfields in RECORD_TYPE should follow the
 225      Microsoft Visual C++ bitfield layout rules.  */
 226   bool (* ms_bitfield_layout_p) PARAMS ((tree record_type));
 227
 228   /* Set up target-specific built-in functions.  */
 229   void (* init_builtins) PARAMS ((void));
 230
 231   /* Expand a target-specific builtin.  */
 232   rtx (* expand_builtin) PARAMS ((tree exp, rtx target, rtx subtarget,
 233                                   enum machine_mode mode, int ignore));
 234
 235   /* Given a decl, a section name, and whether the decl initializer
 236      has relocs, choose attributes for the section.  */
 237   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 238   unsigned int (* section_type_flags) PARAMS ((tree, const char *, int));
 239
 240   /* True if new jumps cannot be created, to replace existing ones or
 241      not, at the current point in the compilation.  */
 242   bool (* cannot_modify_jumps_p) PARAMS ((void));
 243
 244   /* True if EXP should be placed in a "small data" section.  */
 245   bool (* in_small_data_p) PARAMS ((tree));
 246
 247   /* True if EXP names an object for which name resolution must resolve
 248      to the current module.  */
 249   bool (* binds_local_p) PARAMS ((tree));
 250
 251   /* Do something target-specific to record properties of the DECL into
 252      the associated SYMBOL_REF.  */
 253   void (* encode_section_info) PARAMS ((tree, int));
 254
 255   /* Undo the effects of encode_section_info on the symbol string.  */
 256   const char * (* strip_name_encoding) PARAMS ((const char *));
 257
 258   /* Leave the boolean fields at the end.  */
 259
 260   /* True if arbitrary sections are supported.  */
 261   bool have_named_sections;
 262
 263   /* True if "native" constructors and destructors are supported,
 264      false if we're using collect2 for the job.  */
 265   bool have_ctors_dtors;
 266
 267   /* True if thread-local storage is supported.  */
 268   bool have_tls;
 269
 270   /* True if a small readonly data section is supported.  */
 271   bool have_srodata_section;
 272
 273   /* True if EH frame info sections should be zero-terminated.  */
 274   bool terminate_dw2_eh_frame_info;
 275 };
 276
 277 extern struct gcc_target targetm;