gcc/ada/ali-util.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             A L I . U T I L                              --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2007, 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 child unit provides utility data structures and procedures used
  27 --  for manipulation of ALI data by the gnatbind and gnatmake.
  28
  29 package ALI.Util is
  30
  31    -----------------------
  32    -- Source File Table --
  33    -----------------------
  34
  35    --  A source file table entry is built for every source file that is
  36    --  in the source dependency table of any of the ALI files that make
  37    --  up the current program.
  38
  39    No_Source_Id : constant Source_Id := Source_Id'First;
  40    --  Special value indicating no Source table entry
  41
  42    First_Source_Entry : constant Source_Id := No_Source_Id + 1;
  43    --  Id of first actual entry in table
  44
  45    type Source_Record is record
  46
  47       Sfile : File_Name_Type;
  48       --  Name of source file
  49
  50       Stamp : Time_Stamp_Type;
  51       --  Time stamp value. If Check_Source_Files is set and the source
  52       --  file is located, then Stamp is set from the source file. Otherwise
  53       --  Stamp is set from the latest stamp value found in any of the
  54       --  ALI files for the current program.
  55
  56       Source_Found : Boolean;
  57       --  This flag is set to True if the corresponding source file was
  58       --  located and the Stamp value was set from the actual source file.
  59       --  It is always false if Check_Source_Files is not set.
  60
  61       All_Timestamps_Match : Boolean;
  62       --  This flag is set only if all files referencing this source file
  63       --  have a matching time stamp, and also, if Source_Found is True,
  64       --  then the stamp of the source file also matches. If this flag is
  65       --  True, then checksums for this file are never referenced. We only
  66       --  use checksums if there are time stamp mismatches.
  67
  68       All_Checksums_Match : Boolean;
  69       --  This flag is set only if all files referencing this source file
  70       --  have checksums, and if all these checksums match. If this flag
  71       --  is set to True, then the binder will ignore a timestamp mismatch.
  72       --  An absent checksum causes this flag to be set False, and a mismatch
  73       --  of checksums also causes it to be set False. The checksum of the
  74       --  actual source file (if Source_Found is True) is included only if
  75       --  All_Timestamps_Match is False (since checksums are only interesting
  76       --  if we have time stamp mismatches, and we want to avoid computing the
  77       --  checksum of the source file if it is not needed.)
  78
  79       Checksum : Word;
  80       --  If no dependency line has a checksum for this source file (i.e. the
  81       --  corresponding entries in the source dependency records all have the
  82       --  Checksum_Present flag set False), then this field is undefined. If
  83       --  at least one dependency entry has a checksum present, then this
  84       --  field contains one of the possible checksum values that has been
  85       --  seen. This is used to set All_Checksums_Match properly.
  86
  87    end record;
  88
  89    package Source is new Table.Table (
  90      Table_Component_Type => Source_Record,
  91      Table_Index_Type     => Source_Id,
  92      Table_Low_Bound      => First_Source_Entry,
  93      Table_Initial        => 1000,
  94      Table_Increment      => 200,
  95      Table_Name           => "Source");
  96
  97    procedure Initialize_ALI_Source;
  98    --  Initialize Source table
  99
 100    --------------------------------------------------
 101    -- Subprograms for Manipulating ALI Information --
 102    --------------------------------------------------
 103
 104    procedure Read_ALI (Id : ALI_Id);
 105    --  Process an ALI file which has been read and scanned by looping
 106    --  through all withed units in the ALI file, checking if they have
 107    --  been processed. Each unit that has not yet been processed will
 108    --  be read, scanned, and processed recursively.
 109
 110    procedure Set_Source_Table (A : ALI_Id);
 111    --  Build source table entry corresponding to the ALI file whose id is A
 112
 113    procedure Set_Source_Table;
 114    --  Build the entire source table
 115
 116    function Time_Stamp_Mismatch
 117      (A         : ALI_Id;
 118       Read_Only : Boolean := False) return File_Name_Type;
 119    --  Looks in the Source_Table and checks time stamp mismatches between
 120    --  the sources there and the sources in the Sdep section of ali file whose
 121    --  id is A. If no time stamp mismatches are found No_File is returned.
 122    --  Otherwise return the first file for which there is a mismatch.
 123    --  Note that in check source files mode (Check_Source_Files = True), the
 124    --  time stamp in the Source_Table should be the actual time stamp of the
 125    --  source files. In minimal recompilation mode (Minimal_Recompilation set
 126    --  to True, no mismatch is found if the file's timestamp has not changed.
 127    --  If Read_Only is True, missing sources are not considered.
 128
 129    --------------------------------------------
 130    -- Subprograms for manipulating checksums --
 131    --------------------------------------------
 132
 133    Checksum_Error : constant Word := 16#FFFF_FFFF#;
 134    --  This value is used to indicate an error in computing the checksum.
 135    --  When comparing checksums for smart recompilation, the CRC_Error
 136    --  value is never considered to match. This could possibly result
 137    --  in a false negative, but that is never harmful, it just means
 138    --  that in unusual cases an unnecessary recompilation occurs.
 139
 140    function Get_File_Checksum (Fname : File_Name_Type) return Word;
 141    --  Compute checksum for the given file. As far as possible, this circuit
 142    --  computes exactly the same value computed by the compiler, but it does
 143    --  not matter if it gets it wrong in marginal cases, since the only result
 144    --  is to miss some smart recompilation cases, correct functioning is not
 145    --  affected by a miscomputation. Returns Checksum_Error if the file is
 146    --  missing or has an error.
 147
 148    function Checksums_Match (Checksum1, Checksum2 : Word) return Boolean;
 149    pragma Inline (Checksums_Match);
 150    --  Returns True if Checksum1 and Checksum2 have the same value and are
 151    --  not equal to Checksum_Error, returns False in all other cases. This
 152    --  routine must always be used to compare for checksum equality, to
 153    --  ensure that the case of Checksum_Error is handled properly.
 154
 155 end ALI.Util;