gcc/ada/spark_xrefs.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                           S P A R K _ X R E F S                          --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 2011-2014, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT; see file COPYING3.  If not, go to --
  19 -- http://www.gnu.org/licenses for a complete copy of the license.          --
  20 --                                                                          --
  21 -- GNAT was originally developed  by the GNAT team at  New York University. --
  22 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  23 --                                                                          --
  24 ------------------------------------------------------------------------------
  25
  26 --  This package defines tables used to store information needed for the SPARK
  27 --  mode. It is used by procedures in Lib.Xref.SPARK_Specific to build the
  28 --  SPARK specific cross-references information before writing it out to the
  29 --  ALI file, and by Get_SPARK_Xrefs/Put_SPARK_Xrefs to read and write the text
  30 --  form that is used in the ALI file.
  31
  32 with Types;      use Types;
  33 with GNAT.Table;
  34
  35 package SPARK_Xrefs is
  36
  37    --  SPARK cross-reference information can exist in one of two forms. In the
  38    --  ALI file, it is represented using a text format that is described in
  39    --  this specification.  Internally it is stored using three tables
  40    --  SPARK_Xref_Table, SPARK_Scope_Table and SPARK_File_Table, which are also
  41    --  defined in this unit.
  42
  43    --  Lib.Xref.SPARK_Specific is part of the compiler. It extracts SPARK
  44    --  cross-reference information from the complete set of cross-references
  45    --  generated during compilation.
  46
  47    --  Get_SPARK_Xrefs reads the text lines in ALI format and populates the
  48    --  internal tables with corresponding information.
  49
  50    --  Put_SPARK_Xrefs reads the internal tables and generates text lines in
  51    --  the ALI format.
  52
  53    ----------------------------
  54    -- SPARK Xrefs ALI Format --
  55    ----------------------------
  56
  57    --  SPARK cross-reference information is generated on a unit-by-unit basis
  58    --  in the ALI file, using lines that start with the identifying character F
  59    --  ("Formal"). These lines are generated if Frame_Condition_Mode is True.
  60
  61    --  The SPARK cross-reference information comes after the shared
  62    --  cross-reference information, so it needs not be read by tools like
  63    --  gnatbind, gnatmake etc.
  64
  65    --  -------------------
  66    --  -- Scope Section --
  67    --  -------------------
  68
  69    --  A first section defines the scopes in which entities are defined and
  70    --  referenced. A scope is a package/subprogram declaration/body. Note that
  71    --  a package declaration and body define two different scopes. Similarly, a
  72    --  subprogram declaration and body, when both present, define two different
  73    --  scopes.
  74
  75    --    FD dependency-number filename (-> unit-filename)?
  76
  77    --      This header precedes scope information for the unit identified by
  78    --      dependency number and file name. The dependency number is the index
  79    --      into the generated D lines and is ones-origin (e.g. 2 = reference to
  80    --      second generated D line).
  81
  82    --      The list of FD lines should match the list of D lines defined in the
  83    --      ALI file, in the same order.
  84
  85    --      Note that the filename here will reflect the original name if a
  86    --      Source_Reference pragma was encountered (since all line number
  87    --      references will be with respect to the original file).
  88
  89    --      Note: the filename is redundant in that it could be deduced from the
  90    --      corresponding D line, but it is convenient at least for human
  91    --      reading of the SPARK cross-reference information, and means that
  92    --      the SPARK cross-reference information can stand on its own without
  93    --      needing other parts of the ALI file.
  94
  95    --      The optional unit filename is given only for subunits.
  96
  97    --    FS . scope line type col entity (-> spec-file . spec-scope)?
  98
  99    --      (The ? mark stands for an optional entry in the syntax)
 100
 101    --      scope is the ones-origin scope number for the current file (e.g. 2 =
 102    --      reference to the second FS line in this FD block).
 103
 104    --      line is the line number of the scope entity. The name of the entity
 105    --      starts in column col. Columns are numbered from one, and if
 106    --      horizontal tab characters are present, the column number is computed
 107    --      assuming standard 1,9,17,.. tab stops. For example, if the entity is
 108    --      the first token on the line, and is preceded by space-HT-space, then
 109    --      the column would be column 10.
 110
 111    --      type is a single letter identifying the type of the entity, using
 112    --      the same code as in cross-references:
 113
 114    --        K = package
 115    --        V = function
 116    --        U = procedure
 117
 118    --      col is the column number of the scope entity
 119
 120    --      entity is the name of the scope entity, with casing in the canonical
 121    --      casing for the source file where it is defined.
 122
 123    --      spec-file and spec-scope are respectively the file and scope for the
 124    --      spec corresponding to the current body scope, when they differ.
 125
 126    --  ------------------
 127    --  -- Xref Section --
 128    --  ------------------
 129
 130    --  A second section defines cross-references useful for computing the set
 131    --  of global variables read/written in each subprogram/package.
 132
 133    --    FX dependency-number filename . entity-number entity
 134
 135    --      dependency-number and filename identity a file in FD lines
 136
 137    --      entity-number and identity identify a scope entity in FS lines for
 138    --      the file previously identified.
 139
 140    --    line typ col entity ref*
 141
 142    --      line is the line number of the referenced entity
 143
 144    --      typ is the type of the referenced entity, using a code similar to
 145    --      the one used for cross-references:
 146
 147    --        > = IN parameter
 148    --        < = OUT parameter
 149    --        = = IN OUT parameter
 150    --        * = all other cases
 151
 152    --      col is the column number of the referenced entity
 153
 154    --      entity is the name of the referenced entity as written in the source
 155    --      file where it is defined.
 156
 157    --  There may be zero or more ref entries on each line
 158
 159    --    (file |)? ((. scope :)? line type col)*
 160
 161    --      file is the dependency number of the file with the reference. It and
 162    --      the following vertical bar are omitted if the file is the same as
 163    --      the previous ref, and the refs for the current file are first (and
 164    --      do not need a bar).
 165
 166    --      scope is the scope number of the scope with the reference. It and
 167    --      the following colon are omitted if the scope is the same as the
 168    --      previous ref, and the refs for the current scope are first (and do
 169    --      not need a colon).
 170
 171    --      line is the line number of the reference
 172
 173    --      col is the column number of the reference
 174
 175    --      type is one of the following, using the same code as in
 176    --      cross-references:
 177
 178    --        m = modification
 179    --        r = reference
 180    --        c = reference to constant object
 181    --        s = subprogram reference in a static call
 182
 183    --  Special entries for reads and writes to memory reference a special
 184    --  variable called "__HEAP". These special entries are present in every
 185    --  scope where reads and writes to memory are present. Line and column for
 186    --  this special variable are always 0.
 187
 188    --    Examples: ??? add examples here
 189
 190    --  -------------------------------
 191    --  -- Generated Globals Section --
 192    --  -------------------------------
 193
 194    --  The Generated Globals section is located at the end of the ALI file.
 195
 196    --  All lines introducing information related to the Generated Globals
 197    --  have the string "GG" appearing in the beginning. This string ("GG")
 198    --  should therefore not be used in the beginning of any line that does
 199    --  not relate to Generated Globals.
 200
 201    --  The processing (reading and writing) of this section happens in
 202    --  package Flow_Computed_Globals (from the SPARK 2014 sources), for
 203    --  further information please refer there.
 204
 205    ----------------
 206    -- Xref Table --
 207    ----------------
 208
 209    --  The following table records SPARK cross-references
 210
 211    type Xref_Index is new Int;
 212    --  Used to index values in this table. Values start at 1 and are assigned
 213    --  sequentially as entries are constructed.
 214
 215    type SPARK_Xref_Record is record
 216       Entity_Name : String_Ptr;
 217       --  Pointer to entity name in ALI file
 218
 219       Entity_Line : Nat;
 220       --  Line number for the entity referenced
 221
 222       Etype : Character;
 223       --  Indicates type of entity, using code used in ALI file:
 224       --    > = IN parameter
 225       --    < = OUT parameter
 226       --    = = IN OUT parameter
 227       --    * = all other cases
 228
 229       Entity_Col : Nat;
 230       --  Column number for the entity referenced
 231
 232       File_Num : Nat;
 233       --  Set to the file dependency number for the cross-reference. Note
 234       --  that if no file entry is present explicitly, this is just a copy
 235       --  of the reference for the current cross-reference section.
 236
 237       Scope_Num : Nat;
 238       --  Set to the scope number for the cross-reference. Note that if no
 239       --  scope entry is present explicitly, this is just a copy of the
 240       --  reference for the current cross-reference section.
 241
 242       Line : Nat;
 243       --  Line number for the reference
 244
 245       Rtype : Character;
 246       --  Indicates type of reference, using code used in ALI file:
 247       --    r = reference
 248       --    c = reference to constant object
 249       --    m = modification
 250       --    s = call
 251
 252       Col : Nat;
 253       --  Column number for the reference
 254    end record;
 255
 256    package SPARK_Xref_Table is new GNAT.Table (
 257      Table_Component_Type => SPARK_Xref_Record,
 258      Table_Index_Type     => Xref_Index,
 259      Table_Low_Bound      => 1,
 260      Table_Initial        => 2000,
 261      Table_Increment      => 300);
 262
 263    -----------------
 264    -- Scope Table --
 265    -----------------
 266
 267    --  This table keeps track of the scopes and the corresponding starting and
 268    --  ending indexes (From, To) in the Xref table.
 269
 270    type Scope_Index is new Int;
 271    --  Used to index values in this table. Values start at 1 and are assigned
 272    --  sequentially as entries are constructed.
 273
 274    type SPARK_Scope_Record is record
 275       Scope_Name : String_Ptr;
 276       --  Pointer to scope name in ALI file
 277
 278       File_Num : Nat;
 279       --  Set to the file dependency number for the scope
 280
 281       Scope_Num : Nat;
 282       --  Set to the scope number for the scope
 283
 284       Spec_File_Num : Nat;
 285       --  Set to the file dependency number for the scope corresponding to the
 286       --  spec of the current scope entity, if different, or else 0.
 287
 288       Spec_Scope_Num : Nat;
 289       --  Set to the scope number for the scope corresponding to the spec of
 290       --  the current scope entity, if different, or else 0.
 291
 292       Line : Nat;
 293       --  Line number for the scope
 294
 295       Stype : Character;
 296       --  Indicates type of scope, using code used in ALI file:
 297       --    K = package
 298       --    V = function
 299       --    U = procedure
 300
 301       Col : Nat;
 302       --  Column number for the scope
 303
 304       From_Xref : Xref_Index;
 305       --  Starting index in Xref table for this scope
 306
 307       To_Xref : Xref_Index;
 308       --  Ending index in Xref table for this scope
 309
 310       --  The following component is only used in-memory, not printed out in
 311       --  ALI file.
 312
 313       Scope_Entity : Entity_Id := Empty;
 314       --  Entity (subprogram or package) for the scope
 315    end record;
 316
 317    package SPARK_Scope_Table is new GNAT.Table (
 318      Table_Component_Type => SPARK_Scope_Record,
 319      Table_Index_Type     => Scope_Index,
 320      Table_Low_Bound      => 1,
 321      Table_Initial        => 200,
 322      Table_Increment      => 300);
 323
 324    ----------------
 325    -- File Table --
 326    ----------------
 327
 328    --  This table keeps track of the units and the corresponding starting and
 329    --  ending indexes (From, To) in the Scope table.
 330
 331    type File_Index is new Int;
 332    --  Used to index values in this table. Values start at 1 and are assigned
 333    --  sequentially as entries are constructed.
 334
 335    type SPARK_File_Record is record
 336       File_Name : String_Ptr;
 337       --  Pointer to file name in ALI file
 338
 339       Unit_File_Name : String_Ptr;
 340       --  Pointer to file name for unit in ALI file, when File_Name refers to a
 341       --  subunit. Otherwise null.
 342
 343       File_Num : Nat;
 344       --  Dependency number in ALI file
 345
 346       From_Scope : Scope_Index;
 347       --  Starting index in Scope table for this unit
 348
 349       To_Scope : Scope_Index;
 350       --  Ending index in Scope table for this unit
 351    end record;
 352
 353    package SPARK_File_Table is new GNAT.Table (
 354      Table_Component_Type => SPARK_File_Record,
 355      Table_Index_Type     => File_Index,
 356      Table_Low_Bound      => 1,
 357      Table_Initial        => 20,
 358      Table_Increment      => 200);
 359
 360    ---------------
 361    -- Constants --
 362    ---------------
 363
 364    Name_Of_Heap_Variable : constant String := "__HEAP";
 365    --  Name of special variable used in effects to denote reads and writes
 366    --  through explicit dereference.
 367
 368    -----------------
 369    -- Subprograms --
 370    -----------------
 371
 372    procedure Initialize_SPARK_Tables;
 373    --  Reset tables for a new compilation
 374
 375    procedure dspark;
 376    --  Debug routine to dump internal SPARK cross-reference tables. This is a
 377    --  raw format dump showing exactly what the tables contain.
 378
 379    procedure pspark;
 380    --  Debugging procedure to output contents of SPARK cross-reference binary
 381    --  tables in the format in which they appear in an ALI file.
 382
 383 end SPARK_Xrefs;