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 --                                                                          --
  10 --          Copyright (C) 1992-2001 Free Software Foundation, Inc.          --
  11 --                                                                          --
  12 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  15 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  18 -- for  more details.  You should have  received  a copy of the GNU General --
  19 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  20 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  21 -- MA 02111-1307, USA.                                                      --
  22 --                                                                          --
  23 -- GNAT was originally developed  by the GNAT team at  New York University. --
  24 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  25 --                                                                          --
  26 ------------------------------------------------------------------------------
  27
  28 --  This child unit provides utility data structures and procedures used
  29 --  for manipulation of ALI data by the gnatbind and gnatmake.
  30
  31 package ALI.Util is
  32
  33    -----------------------
  34    -- Source File Table --
  35    -----------------------
  36
  37    --  A source file table entry is built for every source file that is
  38    --  in the source dependency table of any of the ALI files that make
  39    --  up the current program.
  40
  41    No_Source_Id : constant Source_Id := Source_Id'First;
  42    --  Special value indicating no Source table entry
  43
  44    First_Source_Entry : constant Source_Id := No_Source_Id + 1;
  45    --  Id of first actual entry in table
  46
  47    type Source_Record is record
  48
  49       Sfile : File_Name_Type;
  50       --  Name of source file
  51
  52       Stamp : Time_Stamp_Type;
  53       --  Time stamp value. If Check_Source_Files is set and the source
  54       --  file is located, then Stamp is set from the source file. Otherwise
  55       --  Stamp is set from the latest stamp value found in any of the
  56       --  ALI files for the current program.
  57
  58       Source_Found : Boolean;
  59       --  This flag is set to True if the corresponding source file was
  60       --  located and the Stamp value was set from the actual source file.
  61       --  It is always false if Check_Source_Files is not set.
  62
  63       All_Timestamps_Match : Boolean;
  64       --  This flag is set only if all files referencing this source file
  65       --  have a matching time stamp, and also, if Source_Found is True,
  66       --  then the stamp of the source file also matches. If this flag is
  67       --  True, then checksums for this file are never referenced. We only
  68       --  use checksums if there are time stamp mismatches.
  69
  70       All_Checksums_Match : Boolean;
  71       --  This flag is set only if all files referencing this source file
  72       --  have checksums, and if all these checksums match. If this flag
  73       --  is set to True, then the binder will ignore a timestamp mismatch.
  74       --  An absent checksum causes this flag to be set False, and a mismatch
  75       --  of checksums also causes it to be set False. The checksum of the
  76       --  actual source file (if Source_Found is True) is included only if
  77       --  All_Timestamps_Match is False (since checksums are only interesting
  78       --  if we have time stamp mismatches, and we want to avoid computing the
  79       --  checksum of the source file if it is not needed.)
  80
  81       Checksum : Word;
  82       --  If no dependency line has a checksum for this source file (i.e. the
  83       --  corresponding entries in the source dependency records all have the
  84       --  Checksum_Present flag set False), then this field is undefined. If
  85       --  at least one dependency entry has a checksum present, then this
  86       --  field contains one of the possible checksum values that has been
  87       --  seen. This is used to set All_Checksums_Match properly.
  88
  89    end record;
  90
  91    package Source is new Table.Table (
  92      Table_Component_Type => Source_Record,
  93      Table_Index_Type     => Source_Id,
  94      Table_Low_Bound      => First_Source_Entry,
  95      Table_Initial        => 1000,
  96      Table_Increment      => 200,
  97      Table_Name           => "Source");
  98
  99    procedure Initialize_ALI_Source;
 100    --  Initialize Source table
 101
 102    --------------------------------------------------
 103    -- Subprograms for Manipulating ALI Information --
 104    --------------------------------------------------
 105
 106    procedure Read_ALI (Id : ALI_Id);
 107    --  Process an ALI file which has been read and scanned by looping
 108    --  through all withed units in the ALI file; checking if they have
 109    --  been processed; and for each that hasn't, reading, scanning, and
 110    --  recursively processing.
 111
 112    procedure Set_Source_Table (A : ALI_Id);
 113    --  Build source table entry corresponding to the ALI file whose id is A.
 114
 115    procedure Set_Source_Table;
 116    --  Build the entire source table.
 117
 118    function Time_Stamp_Mismatch (A : ALI_Id) 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
 128    --------------------------------------------
 129    -- Subprograms for manipulating checksums --
 130    --------------------------------------------
 131
 132    Checksum_Error : constant Word := 16#FFFF_FFFF#;
 133    --  This value is used to indicate an error in computing the checksum.
 134    --  When comparing checksums for smart recompilation, the CRC_Error
 135    --  value is never considered to match. This could possibly result
 136    --  in a false negative, but that is never harmful, it just means
 137    --  that in unusual cases an unnecessary recompilation occurs.
 138
 139    function Get_File_Checksum (Fname : Name_Id) return Word;
 140    --  Compute checksum for the given file. As far as possible, this circuit
 141    --  computes exactly the same value computed by the compiler, but it does
 142    --  not matter if it gets it wrong in marginal cases, since the only result
 143    --  is to miss some smart recompilation cases, correct functioning is not
 144    --  affected by a miscomputation. Returns Checksum_Error if the file is
 145    --  missing or has an error.
 146
 147    function Checksums_Match (Checksum1, Checksum2 : Word) return Boolean;
 148    pragma Inline (Checksums_Match);
 149    --  Returns True if Checksum1 and Checksum2 have the same value and are
 150    --  not equal to Checksum_Error, returns False in all other cases. This
 151    --  routine must always be used to compare for checksum equality, to
 152    --  ensure that the case of Checksum_Error is handled properly.
 153
 154 end ALI.Util;