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 the assembler code for entry to a function.  */
  73     void (* function_prologue) PARAMS ((FILE *, HOST_WIDE_INT));
  74
  75     /* Output the assembler code for end of prologue.  */
  76     void (* function_end_prologue) PARAMS ((FILE *));
  77
  78     /* Output the assembler code for start of epilogue.  */
  79     void (* function_begin_epilogue) PARAMS ((FILE *));
  80
  81     /* Output the assembler code for function exit.  */
  82     void (* function_epilogue) PARAMS ((FILE *, HOST_WIDE_INT));
  83
  84     /* Switch to an arbitrary section NAME with attributes as
  85        specified by FLAGS.  */
  86     void (* named_section) PARAMS ((const char *, unsigned int));
  87
  88     /* Switch to the section that holds the exception table.  */
  89     void (* exception_section) PARAMS ((void));
  90
  91     /* Switch to the section that holds the exception frames.  */
  92     void (* eh_frame_section) PARAMS ((void));
  93
  94     /* Select and switch to a section for EXP.  It may be a DECL or a
  95        constant for which TREE_CST_RTL is valid.  RELOC is non-zero if
  96        runtime relocations must be applied; bit 1 will be set if the
  97        runtime relocations require non-local name resolution.  ALIGN is
  98        the required alignment of the data.  */
  99     void (* select_section) PARAMS ((tree, int, unsigned HOST_WIDE_INT));
 100
 101     /* Select and switch to a section for X with MODE.  ALIGN is
 102        the desired alignment of the data.  */
 103     void (* select_rtx_section) PARAMS ((enum machine_mode, rtx,
 104                                          unsigned HOST_WIDE_INT));
 105
 106     /* Select a unique section name for DECL.  RELOC is the same as
 107        for SELECT_SECTION.  */
 108     void (* unique_section) PARAMS ((tree, int));
 109
 110     /* Output a constructor for a symbol with a given priority.  */
 111     void (* constructor) PARAMS ((rtx, int));
 112
 113     /* Output a destructor for a symbol with a given priority.  */
 114     void (* destructor) PARAMS ((rtx, int));
 115   } asm_out;
 116
 117   /* Functions relating to instruction scheduling.  */
 118   struct sched
 119   {
 120     /* Given the current cost, COST, of an insn, INSN, calculate and
 121        return a new cost based on its relationship to DEP_INSN through
 122        the dependence LINK.  The default is to make no adjustment.  */
 123     int (* adjust_cost) PARAMS ((rtx insn, rtx link, rtx def_insn, int cost));
 124
 125     /* Adjust the priority of an insn as you see fit.  Returns the new
 126        priority.  */
 127     int (* adjust_priority) PARAMS ((rtx, int));
 128
 129     /* Function which returns the maximum number of insns that can be
 130        scheduled in the same machine cycle.  This must be constant
 131        over an entire compilation.  The default is 1.  */
 132     int (* issue_rate) PARAMS ((void));
 133
 134     /* Calculate how much this insn affects how many more insns we
 135        can emit this cycle.  Default is they all cost the same.  */
 136     int (* variable_issue) PARAMS ((FILE *, int, rtx, int));
 137
 138     /* Initialize machine-dependent scheduling code.  */
 139     void (* md_init) PARAMS ((FILE *, int, int));
 140
 141     /* Finalize machine-dependent scheduling code.  */
 142     void (* md_finish) PARAMS ((FILE *, int));
 143
 144     /* Reorder insns in a machine-dependent fashion, in two different
 145        places.  Default does nothing.  */
 146     int (* reorder)  PARAMS ((FILE *, int, rtx *, int *, int));
 147     int (* reorder2) PARAMS ((FILE *, int, rtx *, int *, int));
 148
 149     /* The following member value is a pointer to a function returning
 150        nonzero if we should use DFA based scheduling.  The default is
 151        to use the old pipeline scheduler.  */
 152     int (* use_dfa_pipeline_interface) PARAMS ((void));
 153     /* The values of all the following members are used only for the
 154        DFA based scheduler: */
 155     /* The values of the following four members are pointers to
 156        functions used to simplify the automaton descriptions.
 157        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 158        returning insns which are used to change the pipeline hazard
 159        recognizer state when the new simulated processor cycle
 160        correspondingly starts and finishes.  The function defined by
 161        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 162        to initialize the corresponding insns.  The default values of
 163        the memebers result in not changing the automaton state when
 164        the new simulated processor cycle correspondingly starts and
 165        finishes.  */
 166     void (* init_dfa_pre_cycle_insn) PARAMS ((void));
 167     rtx (* dfa_pre_cycle_insn) PARAMS ((void));
 168     void (* init_dfa_post_cycle_insn) PARAMS ((void));
 169     rtx (* dfa_post_cycle_insn) PARAMS ((void));
 170     /* The following member value is a pointer to a function returning value
 171        which defines how many insns in queue `ready' will we try for
 172        multi-pass scheduling.  if the member value is nonzero and the
 173        function returns positive value, the DFA based scheduler will make
 174        multi-pass scheduling for the first cycle.  In other words, we will
 175        try to choose ready insn which permits to start maximum number of
 176        insns on the same cycle.  */
 177     int (* first_cycle_multipass_dfa_lookahead) PARAMS ((void));
 178     /* The values of the following members are pointers to functions
 179        used to improve the first cycle multipass scheduling by
 180        inserting nop insns.  dfa_scheduler_bubble gives a function
 181        returning a nop insn with given index.  The indexes start with
 182        zero.  The function should return NULL if there are no more nop
 183        insns with indexes greater than given index.  To initialize the
 184        nop insn the function given by member
 185        init_dfa_scheduler_bubbles is used.  The default values of the
 186        members result in not inserting nop insns during the multipass
 187        scheduling.  */
 188     void (* init_dfa_bubbles) PARAMS ((void));
 189     rtx (* dfa_bubble) PARAMS ((int));
 190   } sched;
 191
 192   /* Given two decls, merge their attributes and return the result.  */
 193   tree (* merge_decl_attributes) PARAMS ((tree, tree));
 194
 195   /* Given two types, merge their attributes and return the result.  */
 196   tree (* merge_type_attributes) PARAMS ((tree, tree));
 197
 198   /* Table of machine attributes and functions to handle them.
 199      Ignored if NULL.  */
 200   const struct attribute_spec *attribute_table;
 201
 202   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 203      one if they are compatible and two if they are nearly compatible
 204      (which causes a warning to be generated).  */
 205   int (* comp_type_attributes) PARAMS ((tree type1, tree type2));
 206
 207   /* Assign default attributes to the newly defined TYPE.  */
 208   void (* set_default_type_attributes) PARAMS ((tree type));
 209
 210   /* Insert attributes on the newly created DECL.  */
 211   void (* insert_attributes) PARAMS ((tree decl, tree *attributes));
 212
 213   /* Return true if FNDECL (which has at least one machine attribute)
 214      can be inlined despite its machine attributes, false otherwise.  */
 215   bool (* function_attribute_inlinable_p) PARAMS ((tree fndecl));
 216
 217   /* Return true if bitfields in RECORD_TYPE should follow the
 218      Microsoft Visual C++ bitfield layout rules.  */
 219   bool (* ms_bitfield_layout_p) PARAMS ((tree record_type));
 220
 221   /* Set up target-specific built-in functions.  */
 222   void (* init_builtins) PARAMS ((void));
 223
 224   /* Expand a target-specific builtin.  */
 225   rtx (* expand_builtin) PARAMS ((tree exp, rtx target, rtx subtarget,
 226                                   enum machine_mode mode, int ignore));
 227
 228   /* Given a decl, a section name, and whether the decl initializer
 229      has relocs, choose attributes for the section.  */
 230   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 231   unsigned int (* section_type_flags) PARAMS ((tree, const char *, int));
 232
 233   /* True if new jumps cannot be created, to replace existing ones or
 234      not, at the current point in the compilation.  */
 235   bool (* cannot_modify_jumps_p) PARAMS ((void));
 236
 237   /* True if EXP should be placed in a "small data" section.  */
 238   bool (* in_small_data_p) PARAMS ((tree));
 239
 240   /* True if EXP names an object for which name resolution must resolve
 241      to the current module.  */
 242   bool (* binds_local_p) PARAMS ((tree));
 243
 244   /* Do something target-specific to record properties of the DECL into
 245      the associated SYMBOL_REF.  */
 246   void (* encode_section_info) PARAMS ((tree, int));
 247
 248   /* Undo the effects of encode_section_info on the symbol string.  */
 249   const char * (* strip_name_encoding) PARAMS ((const char *));
 250
 251   /* Leave the boolean fields at the end.  */
 252
 253   /* True if arbitrary sections are supported.  */
 254   bool have_named_sections;
 255
 256   /* True if "native" constructors and destructors are supported,
 257      false if we're using collect2 for the job.  */
 258   bool have_ctors_dtors;
 259
 260   /* True if thread-local storage is supported.  */
 261   bool have_tls;
 262 };
 263
 264 extern struct gcc_target targetm;