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