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     /* Output a constructor for a symbol with a given priority.  */
  95     void (* constructor) PARAMS ((rtx, int));
  96
  97     /* Output a destructor for a symbol with a given priority.  */
  98     void (* destructor) PARAMS ((rtx, int));
  99   } asm_out;
 100
 101   /* Functions relating to instruction scheduling.  */
 102   struct sched
 103   {
 104     /* Given the current cost, COST, of an insn, INSN, calculate and
 105        return a new cost based on its relationship to DEP_INSN through
 106        the dependence LINK.  The default is to make no adjustment.  */
 107     int (* adjust_cost) PARAMS ((rtx insn, rtx link, rtx def_insn, int cost));
 108
 109     /* Adjust the priority of an insn as you see fit.  Returns the new
 110        priority.  */
 111     int (* adjust_priority) PARAMS ((rtx, int));
 112
 113     /* Function which returns the maximum number of insns that can be
 114        scheduled in the same machine cycle.  This must be constant
 115        over an entire compilation.  The default is 1.  */
 116     int (* issue_rate) PARAMS ((void));
 117
 118     /* Calculate how much this insn affects how many more insns we
 119        can emit this cycle.  Default is they all cost the same.  */
 120     int (* variable_issue) PARAMS ((FILE *, int, rtx, int));
 121
 122     /* Initialize machine-dependent scheduling code.  */
 123     void (* md_init) PARAMS ((FILE *, int, int));
 124
 125     /* Finalize machine-dependent scheduling code.  */
 126     void (* md_finish) PARAMS ((FILE *, int));
 127
 128     /* Reorder insns in a machine-dependent fashion, in two different
 129        places.  Default does nothing.  */
 130     int (* reorder)  PARAMS ((FILE *, int, rtx *, int *, int));
 131     int (* reorder2) PARAMS ((FILE *, int, rtx *, int *, int));
 132
 133     /* cycle_display is a pointer to a function which can emit
 134        data into the assembly stream about the current cycle.
 135        Arguments are CLOCK, the data to emit, and LAST, the last
 136        insn in the new chain we're building.  Returns a new LAST.
 137        The default is to do nothing.  */
 138     rtx (* cycle_display) PARAMS ((int clock, rtx last));
 139   } sched;
 140
 141   /* Given two decls, merge their attributes and return the result.  */
 142   tree (* merge_decl_attributes) PARAMS ((tree, tree));
 143
 144   /* Given two types, merge their attributes and return the result.  */
 145   tree (* merge_type_attributes) PARAMS ((tree, tree));
 146
 147   /* Table of machine attributes and functions to handle them.  */
 148   const struct attribute_spec *attribute_table;
 149
 150   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 151      one if they are compatible and two if they are nearly compatible
 152      (which causes a warning to be generated).  */
 153   int (* comp_type_attributes) PARAMS ((tree type1, tree type2));
 154
 155   /* Assign default attributes to the newly defined TYPE.  */
 156   void (* set_default_type_attributes) PARAMS ((tree type));
 157
 158   /* Insert attributes on the newly created DECL.  */
 159   void (* insert_attributes) PARAMS ((tree decl, tree *attributes));
 160
 161   /* Return true if FNDECL (which has at least one machine attribute)
 162      can be inlined despite its machine attributes, false otherwise.  */
 163   bool (* function_attribute_inlinable_p) PARAMS ((tree fndecl));
 164
 165   /* Return true if bitfields in RECORD_TYPE should follow the
 166      Microsoft Visual C++ bitfield layout rules.  */
 167   bool (* ms_bitfield_layout_p) PARAMS ((tree record_type));
 168
 169   /* Set up target-specific built-in functions.  */
 170   void (* init_builtins) PARAMS ((void));
 171
 172   /* Expand a target-specific builtin.  */
 173   rtx (* expand_builtin) PARAMS ((tree exp, rtx target, rtx subtarget,
 174                                   enum machine_mode mode, int ignore));
 175
 176   /* Given a decl, a section name, and whether the decl initializer
 177      has relocs, choose attributes for the section.  */
 178   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 179   unsigned int (* section_type_flags) PARAMS ((tree, const char *, int));
 180
 181   /* True if arbitrary sections are supported.  */
 182   bool have_named_sections;
 183
 184   /* True if "native" constructors and destructors are supported,
 185      false if we're using collect2 for the job.  */
 186   bool have_ctors_dtors;
 187
 188   /* True if new jumps cannot be created, to replace existing ones or
 189      not, at the current point in the compilation.  */
 190   bool (* cannot_modify_jumps_p) PARAMS ((void));
 191 };
 192
 193 extern struct gcc_target targetm;