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) 1992-2018, 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 gnatbind and gnatmake.
  28
  29 package ALI.Util is
  30
  31    -----------------------
  32    -- Source File Table --
  33    -----------------------
  34
  35    --  A table entry is built for every source file that is in the source
  36    --  dependency table of any ALI file that is part of the current program.
  37
  38    No_Source_Id : constant Source_Id := Source_Id'First;
  39    --  Special value indicating no Source table entry
  40
  41    First_Source_Entry : constant Source_Id := No_Source_Id + 1;
  42    --  Id of first actual entry in table
  43
  44    type Source_Record is record
  45
  46       Sfile : File_Name_Type;
  47       --  Name of source file
  48
  49       Stamp : Time_Stamp_Type;
  50       --  Time stamp value. If Check_Source_Files is set and the source
  51       --  file is located, then Stamp is set from the source file. Otherwise
  52       --  Stamp is set from the latest stamp value found in any of the
  53       --  ALI files for the current program.
  54
  55       Source_Found : Boolean;
  56       --  This flag is set to True if the corresponding source file was
  57       --  located and the Stamp value was set from the actual source file.
  58       --  It is always false if Check_Source_Files is not set.
  59
  60       Stamp_File : File_Name_Type;
  61       --  File that Stamp came from. If Source_Found is True, then Stamp is the
  62       --  timestamp of the source file, and this is the name of the source
  63       --  file. If Source_Found is False, then Stamp comes from a dependency
  64       --  line in an ALI file, this is the name of that ALI file. Used only in
  65       --  verbose mode, for messages.
  66
  67       All_Timestamps_Match : Boolean;
  68       --  This flag is set only if all files referencing this source file
  69       --  have a matching time stamp, and also, if Source_Found is True,
  70       --  then the stamp of the source file also matches. If this flag is
  71       --  True, then checksums for this file are never referenced. We only
  72       --  use checksums if there are time stamp mismatches.
  73
  74       All_Checksums_Match : Boolean;
  75       --  This flag is set only if all files referencing this source file
  76       --  have checksums, and if all these checksums match. If this flag
  77       --  is set to True, then the binder will ignore a timestamp mismatch.
  78       --  An absent checksum causes this flag to be set False, and a mismatch
  79       --  of checksums also causes it to be set False. The checksum of the
  80       --  actual source file (if Source_Found is True) is included only if
  81       --  All_Timestamps_Match is False (since checksums are only interesting
  82       --  if we have time stamp mismatches, and we want to avoid computing the
  83       --  checksum of the source file if it is not needed.)
  84
  85       Checksum : Word;
  86       --  If no dependency line has a checksum for this source file (i.e. the
  87       --  corresponding entries in the source dependency records all have the
  88       --  Checksum_Present flag set False), then this field is undefined. If
  89       --  at least one dependency entry has a checksum present, then this
  90       --  field contains one of the possible checksum values that has been
  91       --  seen. This is used to set All_Checksums_Match properly.
  92
  93    end record;
  94
  95    package Source is new Table.Table (
  96      Table_Component_Type => Source_Record,
  97      Table_Index_Type     => Source_Id,
  98      Table_Low_Bound      => First_Source_Entry,
  99      Table_Initial        => 1000,
 100      Table_Increment      => 200,
 101      Table_Name           => "Source");
 102
 103    procedure Initialize_ALI_Source;
 104    --  Initialize Source table
 105
 106    --------------------------------------------------
 107    -- Subprograms for Manipulating ALI Information --
 108    --------------------------------------------------
 109
 110    procedure Read_Withed_ALIs
 111      (Id            : ALI_Id;
 112       Ignore_Errors : Boolean := False);
 113    --  Process an ALI file which has been read and scanned by looping through
 114    --  all withed units in the ALI file, checking if they have been processed.
 115    --  Each unit that has not yet been processed will be read, scanned, and
 116    --  processed recursively. If Ignore_Errors is True, then failure to read an
 117    --  ALI file is not reported as an error, and scanning continues with other
 118    --  ALI files.
 119
 120    procedure Set_Source_Table (A : ALI_Id);
 121    --  Build source table entry corresponding to the ALI file whose id is A
 122
 123    procedure Set_Source_Table;
 124    --  Build the entire source table
 125
 126    function Time_Stamp_Mismatch
 127      (A         : ALI_Id;
 128       Read_Only : Boolean := False) return File_Name_Type;
 129    --  Looks in the Source_Table and checks time stamp mismatches between
 130    --  the sources there and the sources in the Sdep section of ali file whose
 131    --  id is A. If no time stamp mismatches are found No_File is returned.
 132    --  Otherwise return the first file for which there is a mismatch.
 133    --  Note that in check source files mode (Check_Source_Files = True), the
 134    --  time stamp in the Source_Table should be the actual time stamp of the
 135    --  source files. In minimal recompilation mode (Minimal_Recompilation set
 136    --  to True, no mismatch is found if the file's timestamp has not changed.
 137    --  If Read_Only is True, missing sources are not considered.
 138
 139    --------------------------------------------
 140    -- Subprograms for manipulating checksums --
 141    --------------------------------------------
 142
 143    Checksum_Error : constant Word := 16#FFFF_FFFF#;
 144    --  This value is used to indicate an error in computing the checksum.
 145    --  When comparing checksums for smart recompilation, the CRC_Error
 146    --  value is never considered to match. This could possibly result
 147    --  in a false negative, but that is never harmful, it just means
 148    --  that in unusual cases an unnecessary recompilation occurs.
 149
 150    function Get_File_Checksum (Fname : File_Name_Type) return Word;
 151    --  Compute checksum for the given file. As far as possible, this circuit
 152    --  computes exactly the same value computed by the compiler, but it does
 153    --  not matter if it gets it wrong in marginal cases, since the only result
 154    --  is to miss some smart recompilation cases, correct functioning is not
 155    --  affected by a miscomputation. Returns Checksum_Error if the file is
 156    --  missing or has an error.
 157
 158    function Checksums_Match (Checksum1, Checksum2 : Word) return Boolean;
 159    pragma Inline (Checksums_Match);
 160    --  Returns True if Checksum1 and Checksum2 have the same value and are
 161    --  not equal to Checksum_Error, returns False in all other cases. This
 162    --  routine must always be used to compare for checksum equality, to
 163    --  ensure that the case of Checksum_Error is handled properly.
 164
 165 end ALI.Util;