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|
------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- B I N D E --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2010, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING3. If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with Binderr; use Binderr;
with Butil; use Butil;
with Debug; use Debug;
with Fname; use Fname;
with Namet; use Namet;
with Opt; use Opt;
with Osint;
with Output; use Output;
with Targparm; use Targparm;
with System.Case_Util; use System.Case_Util;
package body Binde is
-- The following data structures are used to represent the graph that is
-- used to determine the elaboration order (using a topological sort).
-- The following structures are used to record successors. If A is a
-- successor of B in this table, it means that A must be elaborated
-- before B is elaborated.
type Successor_Id is new Nat;
-- Identification of single successor entry
No_Successor : constant Successor_Id := 0;
-- Used to indicate end of list of successors
type Elab_All_Id is new Nat;
-- Identification of Elab_All entry link
No_Elab_All_Link : constant Elab_All_Id := 0;
-- Used to indicate end of list
-- Succ_Reason indicates the reason for a particular elaboration link
type Succ_Reason is
(Withed,
-- After directly with's Before, so the spec of Before must be
-- elaborated before After is elaborated.
Elab,
-- After directly mentions Before in a pragma Elaborate, so the
-- body of Before must be elaborate before After is elaborated.
Elab_All,
-- After either mentions Before directly in a pragma Elaborate_All,
-- or mentions a third unit, X, which itself requires that Before be
-- elaborated before unit X is elaborated. The Elab_All_Link list
-- traces the dependencies in the latter case.
Elab_All_Desirable,
-- This is just like Elab_All, except that the elaborate all was not
-- explicitly present in the source, but rather was created by the
-- front end, which decided that it was "desirable".
Elab_Desirable,
-- This is just like Elab, except that the elaborate was not
-- explicitly present in the source, but rather was created by the
-- front end, which decided that it was "desirable".
Spec_First);
-- After is a body, and Before is the corresponding spec
-- Successor_Link contains the information for one link
type Successor_Link is record
Before : Unit_Id;
-- Predecessor unit
After : Unit_Id;
-- Successor unit
Next : Successor_Id;
-- Next successor on this list
Reason : Succ_Reason;
-- Reason for this link
Elab_Body : Boolean;
-- Set True if this link is needed for the special Elaborate_Body
-- processing described below.
Reason_Unit : Unit_Id;
-- For Reason = Elab, or Elab_All or Elab_Desirable, records the unit
-- containing the pragma leading to the link.
Elab_All_Link : Elab_All_Id;
-- If Reason = Elab_All or Elab_Desirable, then this points to the
-- first elment in a list of Elab_All entries that record the with
-- chain leading resulting in this particular dependency.
end record;
-- Note on handling of Elaborate_Body. Basically, if we have a pragma
-- Elaborate_Body in a unit, it means that the spec and body have to
-- be handled as a single entity from the point of view of determining
-- an elaboration order. What we do is to essentially remove the body
-- from consideration completely, and transfer all its links (other
-- than the spec link) to the spec. Then when then the spec gets chosen,
-- we choose the body right afterwards. We mark the links that get moved
-- from the body to the spec by setting their Elab_Body flag True, so
-- that we can understand what is going on!
Succ_First : constant := 1;
package Succ is new Table.Table (
Table_Component_Type => Successor_Link,
Table_Index_Type => Successor_Id,
Table_Low_Bound => Succ_First,
Table_Initial => 500,
Table_Increment => 200,
Table_Name => "Succ");
-- For the case of Elaborate_All, the following table is used to record
-- chains of with relationships that lead to the Elab_All link. These
-- are used solely for diagnostic purposes
type Elab_All_Entry is record
Needed_By : Unit_Name_Type;
-- Name of unit from which referencing unit was with'ed or otherwise
-- needed as a result of Elaborate_All or Elaborate_Desirable.
Next_Elab : Elab_All_Id;
-- Link to next entry on chain (No_Elab_All_Link marks end of list)
end record;
package Elab_All_Entries is new Table.Table (
Table_Component_Type => Elab_All_Entry,
Table_Index_Type => Elab_All_Id,
Table_Low_Bound => 1,
Table_Initial => 2000,
Table_Increment => 200,
Table_Name => "Elab_All_Entries");
-- A Unit_Node record is built for each active unit
type Unit_Node_Record is record
Successors : Successor_Id;
-- Pointer to list of links for successor nodes
Num_Pred : Int;
-- Number of predecessors for this unit. Normally non-negative, but
-- can go negative in the case of units chosen by the diagnose error
-- procedure (when cycles are being removed from the graph).
Nextnp : Unit_Id;
-- Forward pointer for list of units with no predecessors
Elab_Order : Nat;
-- Position in elaboration order (zero = not placed yet)
Visited : Boolean;
-- Used in computing transitive closure for elaborate all and
-- also in locating cycles and paths in the diagnose routines.
Elab_Position : Natural;
-- Initialized to zero. Set non-zero when a unit is chosen and
-- placed in the elaboration order. The value represents the
-- ordinal position in the elaboration order.
end record;
package UNR is new Table.Table (
Table_Component_Type => Unit_Node_Record,
Table_Index_Type => Unit_Id,
Table_Low_Bound => First_Unit_Entry,
Table_Initial => 500,
Table_Increment => 200,
Table_Name => "UNR");
No_Pred : Unit_Id;
-- Head of list of items with no predecessors
Num_Left : Int;
-- Number of entries not yet dealt with
Cur_Unit : Unit_Id;
-- Current unit, set by Gather_Dependencies, and picked up in Build_Link
-- to set the Reason_Unit field of the created dependency link.
Num_Chosen : Natural := 0;
-- Number of units chosen in the elaboration order so far
-----------------------
-- Local Subprograms --
-----------------------
function Better_Choice (U1, U2 : Unit_Id) return Boolean;
-- U1 and U2 are both permitted candidates for selection as the next unit
-- to be elaborated. This function determines whether U1 is a better choice
-- than U2, i.e. should be elaborated in preference to U2, based on a set
-- of heuristics that establish a friendly and predictable order (see body
-- for details). The result is True if U1 is a better choice than U2, and
-- False if it is a worse choice, or there is no preference between them.
procedure Build_Link
(Before : Unit_Id;
After : Unit_Id;
R : Succ_Reason;
Ea_Id : Elab_All_Id := No_Elab_All_Link);
-- Establish a successor link, Before must be elaborated before After, and
-- the reason for the link is R. Ea_Id is the contents to be placed in the
-- Elab_All_Link of the entry.
procedure Choose (Chosen : Unit_Id);
-- Chosen is the next entry chosen in the elaboration order. This procedure
-- updates all data structures appropriately.
function Corresponding_Body (U : Unit_Id) return Unit_Id;
pragma Inline (Corresponding_Body);
-- Given a unit which is a spec for which there is a separate body, return
-- the unit id of the body. It is an error to call this routine with a unit
-- that is not a spec, or which does not have a separate body.
function Corresponding_Spec (U : Unit_Id) return Unit_Id;
pragma Inline (Corresponding_Spec);
-- Given a unit which is a body for which there is a separate spec, return
-- the unit id of the spec. It is an error to call this routine with a unit
-- that is not a body, or which does not have a separate spec.
procedure Diagnose_Elaboration_Problem;
-- Called when no elaboration order can be found. Outputs an appropriate
-- diagnosis of the problem, and then abandons the bind.
procedure Elab_All_Links
(Before : Unit_Id;
After : Unit_Id;
Reason : Succ_Reason;
Link : Elab_All_Id);
-- Used to compute the transitive closure of elaboration links for an
-- Elaborate_All pragma (Reason = Elab_All) or for an indication of
-- Elaborate_All_Desirable (Reason = Elab_All_Desirable). Unit After has
-- a pragma Elaborate_All or the front end has determined that a reference
-- probably requires Elaborate_All is required, and unit Before must be
-- previously elaborated. First a link is built making sure that unit
-- Before is elaborated before After, then a recursive call ensures that
-- we also build links for any units needed by Before (i.e. these units
-- must/should also be elaborated before After). Link is used to build
-- a chain of Elab_All_Entries to explain the reason for a link. The
-- value passed is the chain so far.
procedure Elab_Error_Msg (S : Successor_Id);
-- Given a successor link, outputs an error message of the form
-- "$ must be elaborated before $ ..." where ... is the reason.
procedure Gather_Dependencies;
-- Compute dependencies, building the Succ and UNR tables
function Is_Body_Unit (U : Unit_Id) return Boolean;
pragma Inline (Is_Body_Unit);
-- Determines if given unit is a body
function Is_Pure_Or_Preelab_Unit (U : Unit_Id) return Boolean;
-- Returns True if corresponding unit is Pure or Preelaborate. Includes
-- dealing with testing flags on spec if it is given a body.
function Is_Waiting_Body (U : Unit_Id) return Boolean;
pragma Inline (Is_Waiting_Body);
-- Determines if U is a waiting body, defined as a body which has
-- not been elaborated, but whose spec has been elaborated.
function Make_Elab_Entry
(Unam : Unit_Name_Type;
Link : Elab_All_Id) return Elab_All_Id;
-- Make an Elab_All_Entries table entry with the given Unam and Link
function Pessimistic_Better_Choice (U1, U2 : Unit_Id) return Boolean;
-- This is like Better_Choice, and has the same interface, but returns
-- true if U1 is a worse choice than U2 in the sense of the -p (pessimistic
-- elaboration order) switch. We still have to obey Ada rules, so it is
-- not quite the direct inverse of Better_Choice.
function Unit_Id_Of (Uname : Unit_Name_Type) return Unit_Id;
-- This function uses the Info field set in the names table to obtain
-- the unit Id of a unit, given its name id value.
procedure Write_Dependencies;
-- Write out dependencies (called only if appropriate option is set)
procedure Write_Elab_All_Chain (S : Successor_Id);
-- If the reason for the link S is Elaborate_All or Elaborate_Desirable,
-- then this routine will output the "needed by" explanation chain.
-------------------
-- Better_Choice --
-------------------
function Better_Choice (U1, U2 : Unit_Id) return Boolean is
UT1 : Unit_Record renames Units.Table (U1);
UT2 : Unit_Record renames Units.Table (U2);
begin
if Debug_Flag_B then
Write_Str ("Better_Choice (");
Write_Unit_Name (UT1.Uname);
Write_Str (", ");
Write_Unit_Name (UT2.Uname);
Write_Line (")");
end if;
-- Note: the checks here are applied in sequence, and the ordering is
-- significant (i.e. the more important criteria are applied first).
-- Prefer a waiting body to one that is not a waiting body
if Is_Waiting_Body (U1) and then not Is_Waiting_Body (U2) then
if Debug_Flag_B then
Write_Line (" True: u1 is waiting body, u2 is not");
end if;
return True;
elsif Is_Waiting_Body (U2) and then not Is_Waiting_Body (U1) then
if Debug_Flag_B then
Write_Line (" False: u2 is waiting body, u1 is not");
end if;
return False;
-- Prefer a predefined unit to a non-predefined unit
elsif UT1.Predefined and then not UT2.Predefined then
if Debug_Flag_B then
Write_Line (" True: u1 is predefined, u2 is not");
end if;
return True;
elsif UT2.Predefined and then not UT1.Predefined then
if Debug_Flag_B then
Write_Line (" False: u2 is predefined, u1 is not");
end if;
return False;
-- Prefer an internal unit to a non-internal unit
elsif UT1.Internal and then not UT2.Internal then
if Debug_Flag_B then
Write_Line (" True: u1 is internal, u2 is not");
end if;
return True;
elsif UT2.Internal and then not UT1.Internal then
if Debug_Flag_B then
Write_Line (" False: u2 is internal, u1 is not");
end if;
return False;
-- Prefer a pure or preelaborable unit to one that is not
elsif Is_Pure_Or_Preelab_Unit (U1)
and then not
Is_Pure_Or_Preelab_Unit (U2)
then
if Debug_Flag_B then
Write_Line (" True: u1 is pure/preelab, u2 is not");
end if;
return True;
elsif Is_Pure_Or_Preelab_Unit (U2)
and then not
Is_Pure_Or_Preelab_Unit (U1)
then
if Debug_Flag_B then
Write_Line (" False: u2 is pure/preelab, u1 is not");
end if;
return False;
-- Prefer a body to a spec
elsif Is_Body_Unit (U1) and then not Is_Body_Unit (U2) then
if Debug_Flag_B then
Write_Line (" True: u1 is body, u2 is not");
end if;
return True;
elsif Is_Body_Unit (U2) and then not Is_Body_Unit (U1) then
if Debug_Flag_B then
Write_Line (" False: u2 is body, u1 is not");
end if;
return False;
-- If both are waiting bodies, then prefer the one whose spec is
-- more recently elaborated. Consider the following:
-- spec of A
-- spec of B
-- body of A or B?
-- The normal waiting body preference would have placed the body of
-- A before the spec of B if it could. Since it could not, there it
-- must be the case that A depends on B. It is therefore a good idea
-- to put the body of B first.
elsif Is_Waiting_Body (U1) and then Is_Waiting_Body (U2) then
declare
Result : constant Boolean :=
UNR.Table (Corresponding_Spec (U1)).Elab_Position >
UNR.Table (Corresponding_Spec (U2)).Elab_Position;
begin
if Debug_Flag_B then
if Result then
Write_Line (" True: based on waiting body elab positions");
else
Write_Line (" False: based on waiting body elab positions");
end if;
end if;
return Result;
end;
end if;
-- Remaining choice rules are disabled by Debug flag -do
if not Debug_Flag_O then
-- The following deal with the case of specs which have been marked
-- as Elaborate_Body_Desirable. We generally want to delay these
-- specs as long as possible, so that the bodies have a better chance
-- of being elaborated closer to the specs.
-- If we have two units, one of which is a spec for which this flag
-- is set, and the other is not, we prefer to delay the spec for
-- which the flag is set.
if not UT1.Elaborate_Body_Desirable
and then UT2.Elaborate_Body_Desirable
then
if Debug_Flag_B then
Write_Line (" True: u1 is elab body desirable, u2 is not");
end if;
return True;
elsif not UT2.Elaborate_Body_Desirable
and then UT1.Elaborate_Body_Desirable
then
if Debug_Flag_B then
Write_Line (" False: u1 is elab body desirable, u2 is not");
end if;
return False;
-- If we have two specs that are both marked as Elaborate_Body
-- desirable, we prefer the one whose body is nearer to being able
-- to be elaborated, based on the Num_Pred count. This helps to
-- ensure bodies are as close to specs as possible.
elsif UT1.Elaborate_Body_Desirable
and then UT2.Elaborate_Body_Desirable
then
declare
Result : constant Boolean :=
UNR.Table (Corresponding_Body (U1)).Num_Pred <
UNR.Table (Corresponding_Body (U2)).Num_Pred;
begin
if Debug_Flag_B then
if Result then
Write_Line (" True based on Num_Pred compare");
else
Write_Line (" False based on Num_Pred compare");
end if;
end if;
return Result;
end;
end if;
end if;
-- If we fall through, it means that no preference rule applies, so we
-- use alphabetical order to at least give a deterministic result.
if Debug_Flag_B then
Write_Line (" choose on alpha order");
end if;
return Uname_Less (UT1.Uname, UT2.Uname);
end Better_Choice;
----------------
-- Build_Link --
----------------
procedure Build_Link
(Before : Unit_Id;
After : Unit_Id;
R : Succ_Reason;
Ea_Id : Elab_All_Id := No_Elab_All_Link)
is
Cspec : Unit_Id;
begin
Succ.Increment_Last;
Succ.Table (Succ.Last).Before := Before;
Succ.Table (Succ.Last).Next := UNR.Table (Before).Successors;
UNR.Table (Before).Successors := Succ.Last;
Succ.Table (Succ.Last).Reason := R;
Succ.Table (Succ.Last).Reason_Unit := Cur_Unit;
Succ.Table (Succ.Last).Elab_All_Link := Ea_Id;
-- Deal with special Elab_Body case. If the After of this link is
-- a body whose spec has Elaborate_All set, and this is not the link
-- directly from the body to the spec, then we make the After of the
-- link reference its spec instead, marking the link appropriately.
if Units.Table (After).Utype = Is_Body then
Cspec := Corresponding_Spec (After);
if Units.Table (Cspec).Elaborate_Body
and then Cspec /= Before
then
Succ.Table (Succ.Last).After := Cspec;
Succ.Table (Succ.Last).Elab_Body := True;
UNR.Table (Cspec).Num_Pred := UNR.Table (Cspec).Num_Pred + 1;
return;
end if;
end if;
-- Fall through on normal case
Succ.Table (Succ.Last).After := After;
Succ.Table (Succ.Last).Elab_Body := False;
UNR.Table (After).Num_Pred := UNR.Table (After).Num_Pred + 1;
end Build_Link;
------------
-- Choose --
------------
procedure Choose (Chosen : Unit_Id) is
S : Successor_Id;
U : Unit_Id;
begin
if Debug_Flag_C then
Write_Str ("Choosing Unit ");
Write_Unit_Name (Units.Table (Chosen).Uname);
Write_Eol;
end if;
-- Add to elaboration order. Note that units having no elaboration
-- code are not treated specially yet. The special casing of this
-- is in Bindgen, where Gen_Elab_Calls skips over them. Meanwhile
-- we need them here, because the object file list is also driven
-- by the contents of the Elab_Order table.
Elab_Order.Increment_Last;
Elab_Order.Table (Elab_Order.Last) := Chosen;
-- Remove from No_Pred list. This is a little inefficient and may
-- be we should doubly link the list, but it will do for now!
if No_Pred = Chosen then
No_Pred := UNR.Table (Chosen).Nextnp;
else
-- Note that we just ignore the situation where it does not
-- appear in the No_Pred list, this happens in calls from the
-- Diagnose_Elaboration_Problem routine, where cycles are being
-- removed arbitrarily from the graph.
U := No_Pred;
while U /= No_Unit_Id loop
if UNR.Table (U).Nextnp = Chosen then
UNR.Table (U).Nextnp := UNR.Table (Chosen).Nextnp;
exit;
end if;
U := UNR.Table (U).Nextnp;
end loop;
end if;
-- For all successors, decrement the number of predecessors, and
-- if it becomes zero, then add to no predecessor list.
S := UNR.Table (Chosen).Successors;
while S /= No_Successor loop
U := Succ.Table (S).After;
UNR.Table (U).Num_Pred := UNR.Table (U).Num_Pred - 1;
if Debug_Flag_N then
Write_Str (" decrementing Num_Pred for unit ");
Write_Unit_Name (Units.Table (U).Uname);
Write_Str (" new value = ");
Write_Int (Int (UNR.Table (U).Num_Pred));
Write_Eol;
end if;
if UNR.Table (U).Num_Pred = 0 then
UNR.Table (U).Nextnp := No_Pred;
No_Pred := U;
end if;
S := Succ.Table (S).Next;
end loop;
-- All done, adjust number of units left count and set elaboration pos
Num_Left := Num_Left - 1;
Num_Chosen := Num_Chosen + 1;
UNR.Table (Chosen).Elab_Position := Num_Chosen;
Units.Table (Chosen).Elab_Position := Num_Chosen;
-- If we just chose a spec with Elaborate_Body set, then we
-- must immediately elaborate the body, before any other units.
if Units.Table (Chosen).Elaborate_Body then
-- If the unit is a spec only, then there is no body. This is a bit
-- odd given that Elaborate_Body is here, but it is valid in an
-- RCI unit, where we only have the interface in the stub bind.
if Units.Table (Chosen).Utype = Is_Spec_Only
and then Units.Table (Chosen).RCI
then
null;
else
Choose (Corresponding_Body (Chosen));
end if;
end if;
end Choose;
------------------------
-- Corresponding_Body --
------------------------
-- Currently if the body and spec are separate, then they appear as
-- two separate units in the same ALI file, with the body appearing
-- first and the spec appearing second.
function Corresponding_Body (U : Unit_Id) return Unit_Id is
begin
pragma Assert (Units.Table (U).Utype = Is_Spec);
return U - 1;
end Corresponding_Body;
------------------------
-- Corresponding_Spec --
------------------------
-- Currently if the body and spec are separate, then they appear as
-- two separate units in the same ALI file, with the body appearing
-- first and the spec appearing second.
function Corresponding_Spec (U : Unit_Id) return Unit_Id is
begin
pragma Assert (Units.Table (U).Utype = Is_Body);
return U + 1;
end Corresponding_Spec;
----------------------------------
-- Diagnose_Elaboration_Problem --
----------------------------------
procedure Diagnose_Elaboration_Problem is
function Find_Path (Ufrom, Uto : Unit_Id; ML : Nat) return Boolean;
-- Recursive routine used to find a path from node Ufrom to node Uto.
-- If a path exists, returns True and outputs an appropriate set of
-- error messages giving the path. Also calls Choose for each of the
-- nodes so that they get removed from the remaining set. There are
-- two cases of calls, either Ufrom = Uto for an attempt to find a
-- cycle, or Ufrom is a spec and Uto the corresponding body for the
-- case of an unsatisfiable Elaborate_Body pragma. ML is the minimum
-- acceptable length for a path.
---------------
-- Find_Path --
---------------
function Find_Path (Ufrom, Uto : Unit_Id; ML : Nat) return Boolean is
function Find_Link (U : Unit_Id; PL : Nat) return Boolean;
-- This is the inner recursive routine, it determines if a path
-- exists from U to Uto, and if so returns True and outputs the
-- appropriate set of error messages. PL is the path length
---------------
-- Find_Link --
---------------
function Find_Link (U : Unit_Id; PL : Nat) return Boolean is
S : Successor_Id;
begin
-- Recursion ends if we are at terminating node and the path
-- is sufficiently long, generate error message and return True.
if U = Uto and then PL >= ML then
Choose (U);
return True;
-- All done if already visited, otherwise mark as visited
elsif UNR.Table (U).Visited then
return False;
-- Otherwise mark as visited and look at all successors
else
UNR.Table (U).Visited := True;
S := UNR.Table (U).Successors;
while S /= No_Successor loop
if Find_Link (Succ.Table (S).After, PL + 1) then
Elab_Error_Msg (S);
Choose (U);
return True;
end if;
S := Succ.Table (S).Next;
end loop;
-- Falling through means this does not lead to a path
return False;
end if;
end Find_Link;
-- Start of processing for Find_Path
begin
-- Initialize all non-chosen nodes to not visisted yet
for U in Units.First .. Units.Last loop
UNR.Table (U).Visited := UNR.Table (U).Elab_Position /= 0;
end loop;
-- Now try to find the path
return Find_Link (Ufrom, 0);
end Find_Path;
-- Start of processing for Diagnose_Elaboration_Error
begin
Set_Standard_Error;
-- Output state of things if debug flag N set
if Debug_Flag_N then
declare
NP : Int;
begin
Write_Eol;
Write_Eol;
Write_Str ("Diagnose_Elaboration_Problem called");
Write_Eol;
Write_Str ("List of remaining unchosen units and predecessors");
Write_Eol;
for U in Units.First .. Units.Last loop
if UNR.Table (U).Elab_Position = 0 then
NP := UNR.Table (U).Num_Pred;
Write_Eol;
Write_Str (" Unchosen unit: #");
Write_Int (Int (U));
Write_Str (" ");
Write_Unit_Name (Units.Table (U).Uname);
Write_Str (" (Num_Pred = ");
Write_Int (NP);
Write_Char (')');
Write_Eol;
if NP = 0 then
if Units.Table (U).Elaborate_Body then
Write_Str
(" (not chosen because of Elaborate_Body)");
Write_Eol;
else
Write_Str (" ****************** why not chosen?");
Write_Eol;
end if;
end if;
-- Search links list to find unchosen predecessors
for S in Succ.First .. Succ.Last loop
declare
SL : Successor_Link renames Succ.Table (S);
begin
if SL.After = U
and then UNR.Table (SL.Before).Elab_Position = 0
then
Write_Str (" unchosen predecessor: #");
Write_Int (Int (SL.Before));
Write_Str (" ");
Write_Unit_Name (Units.Table (SL.Before).Uname);
Write_Eol;
NP := NP - 1;
end if;
end;
end loop;
if NP /= 0 then
Write_Str (" **************** Num_Pred value wrong!");
Write_Eol;
end if;
end if;
end loop;
end;
end if;
-- Output the header for the error, and manually increment the
-- error count. We are using Error_Msg_Output rather than Error_Msg
-- here for two reasons:
-- This is really only one error, not one for each line
-- We want this output on standard output since it is voluminous
-- But we do need to deal with the error count manually in this case
Errors_Detected := Errors_Detected + 1;
Error_Msg_Output ("elaboration circularity detected", Info => False);
-- Try to find cycles starting with any of the remaining nodes that have
-- not yet been chosen. There must be at least one (there is some reason
-- we are being called!)
for U in Units.First .. Units.Last loop
if UNR.Table (U).Elab_Position = 0 then
if Find_Path (U, U, 1) then
raise Unrecoverable_Error;
end if;
end if;
end loop;
-- We should never get here, since we were called for some reason,
-- and we should have found and eliminated at least one bad path.
raise Program_Error;
end Diagnose_Elaboration_Problem;
--------------------
-- Elab_All_Links --
--------------------
procedure Elab_All_Links
(Before : Unit_Id;
After : Unit_Id;
Reason : Succ_Reason;
Link : Elab_All_Id)
is
begin
if UNR.Table (Before).Visited then
return;
end if;
-- Build the direct link for Before
UNR.Table (Before).Visited := True;
Build_Link (Before, After, Reason, Link);
-- Process all units with'ed by Before recursively
for W in
Units.Table (Before).First_With .. Units.Table (Before).Last_With
loop
-- Skip if this with is an interface to a stand-alone library.
-- Skip also if no ALI file for this WITH, happens for language
-- defined generics while bootstrapping the compiler (see body of
-- Lib.Writ.Write_With_Lines). Finally, skip if it is a limited
-- with clause, which does not impose an elaboration link.
if not Withs.Table (W).SAL_Interface
and then Withs.Table (W).Afile /= No_File
and then not Withs.Table (W).Limited_With
then
declare
Info : constant Int :=
Get_Name_Table_Info
(Withs.Table (W).Uname);
begin
-- If the unit is unknown, for some unknown reason, fail
-- graciously explaining that the unit is unknown. Without
-- this check, gnatbind will crash in Unit_Id_Of.
if Info = 0 or else Unit_Id (Info) = No_Unit_Id then
declare
Withed : String :=
Get_Name_String (Withs.Table (W).Uname);
Last_Withed : Natural := Withed'Last;
Withing : String :=
Get_Name_String
(Units.Table (Before).Uname);
Last_Withing : Natural := Withing'Last;
Spec_Body : String := " (Spec)";
begin
To_Mixed (Withed);
To_Mixed (Withing);
if Last_Withed > 2 and then
Withed (Last_Withed - 1) = '%'
then
Last_Withed := Last_Withed - 2;
end if;
if Last_Withing > 2 and then
Withing (Last_Withing - 1) = '%'
then
Last_Withing := Last_Withing - 2;
end if;
if Units.Table (Before).Utype = Is_Body or else
Units.Table (Before).Utype = Is_Body_Only
then
Spec_Body := " (Body)";
end if;
Osint.Fail
("could not find unit "
& Withed (Withed'First .. Last_Withed) & " needed by "
& Withing (Withing'First .. Last_Withing) & Spec_Body);
end;
end if;
Elab_All_Links
(Unit_Id_Of (Withs.Table (W).Uname),
After,
Reason,
Make_Elab_Entry (Withs.Table (W).Uname, Link));
end;
end if;
end loop;
-- Process corresponding body, if there is one
if Units.Table (Before).Utype = Is_Spec then
Elab_All_Links
(Corresponding_Body (Before),
After, Reason,
Make_Elab_Entry
(Units.Table (Corresponding_Body (Before)).Uname, Link));
end if;
end Elab_All_Links;
--------------------
-- Elab_Error_Msg --
--------------------
procedure Elab_Error_Msg (S : Successor_Id) is
SL : Successor_Link renames Succ.Table (S);
begin
-- Nothing to do if internal unit involved and no -da flag
if not Debug_Flag_A
and then
(Is_Internal_File_Name (Units.Table (SL.Before).Sfile)
or else
Is_Internal_File_Name (Units.Table (SL.After).Sfile))
then
return;
end if;
-- Here we want to generate output
Error_Msg_Unit_1 := Units.Table (SL.Before).Uname;
if SL.Elab_Body then
Error_Msg_Unit_2 := Units.Table (Corresponding_Body (SL.After)).Uname;
else
Error_Msg_Unit_2 := Units.Table (SL.After).Uname;
end if;
Error_Msg_Output (" $ must be elaborated before $", Info => True);
Error_Msg_Unit_1 := Units.Table (SL.Reason_Unit).Uname;
case SL.Reason is
when Withed =>
Error_Msg_Output
(" reason: with clause",
Info => True);
when Elab =>
Error_Msg_Output
(" reason: pragma Elaborate in unit $",
Info => True);
when Elab_All =>
Error_Msg_Output
(" reason: pragma Elaborate_All in unit $",
Info => True);
when Elab_All_Desirable =>
Error_Msg_Output
(" reason: implicit Elaborate_All in unit $",
Info => True);
Error_Msg_Output
(" recompile $ with -gnatwl for full details",
Info => True);
when Elab_Desirable =>
Error_Msg_Output
(" reason: implicit Elaborate in unit $",
Info => True);
Error_Msg_Output
(" recompile $ with -gnatwl for full details",
Info => True);
when Spec_First =>
Error_Msg_Output
(" reason: spec always elaborated before body",
Info => True);
end case;
Write_Elab_All_Chain (S);
if SL.Elab_Body then
Error_Msg_Unit_1 := Units.Table (SL.Before).Uname;
Error_Msg_Unit_2 := Units.Table (SL.After).Uname;
Error_Msg_Output
(" $ must therefore be elaborated before $",
True);
Error_Msg_Unit_1 := Units.Table (SL.After).Uname;
Error_Msg_Output
(" (because $ has a pragma Elaborate_Body)",
True);
end if;
if not Zero_Formatting then
Write_Eol;
end if;
end Elab_Error_Msg;
---------------------
-- Find_Elab_Order --
---------------------
procedure Find_Elab_Order is
U : Unit_Id;
Best_So_Far : Unit_Id;
begin
Succ.Init;
Num_Left := Int (Units.Last - Units.First + 1);
-- Initialize unit table for elaboration control
for U in Units.First .. Units.Last loop
UNR.Increment_Last;
UNR.Table (UNR.Last).Successors := No_Successor;
UNR.Table (UNR.Last).Num_Pred := 0;
UNR.Table (UNR.Last).Nextnp := No_Unit_Id;
UNR.Table (UNR.Last).Elab_Order := 0;
UNR.Table (UNR.Last).Elab_Position := 0;
end loop;
-- Output warning if -p used with no -gnatE units
if Pessimistic_Elab_Order
and not Dynamic_Elaboration_Checks_Specified
then
if OpenVMS_On_Target then
Error_Msg ("?use of /PESSIMISTIC_ELABORATION questionable");
else
Error_Msg ("?use of -p switch questionable");
end if;
Error_Msg ("?since all units compiled with static elaboration model");
end if;
-- Gather dependencies and output them if option set
Gather_Dependencies;
-- Output elaboration dependencies if option is set
if Elab_Dependency_Output or Debug_Flag_E then
Write_Dependencies;
end if;
-- Initialize the no predecessor list
No_Pred := No_Unit_Id;
for U in UNR.First .. UNR.Last loop
if UNR.Table (U).Num_Pred = 0 then
UNR.Table (U).Nextnp := No_Pred;
No_Pred := U;
end if;
end loop;
-- OK, now we determine the elaboration order proper. All we do is to
-- select the best choice from the no predecessor list until all the
-- nodes have been chosen.
Outer : loop
-- If there are no nodes with predecessors, then either we are
-- done, as indicated by Num_Left being set to zero, or we have
-- a circularity. In the latter case, diagnose the circularity,
-- removing it from the graph and continue
Get_No_Pred : while No_Pred = No_Unit_Id loop
exit Outer when Num_Left < 1;
Diagnose_Elaboration_Problem;
end loop Get_No_Pred;
U := No_Pred;
Best_So_Far := No_Unit_Id;
-- Loop to choose best entry in No_Pred list
No_Pred_Search : loop
if Debug_Flag_N then
Write_Str (" considering choice of ");
Write_Unit_Name (Units.Table (U).Uname);
Write_Eol;
if Units.Table (U).Elaborate_Body then
Write_Str
(" Elaborate_Body = True, Num_Pred for body = ");
Write_Int
(Int (UNR.Table (Corresponding_Body (U)).Num_Pred));
else
Write_Str
(" Elaborate_Body = False");
end if;
Write_Eol;
end if;
-- This is a candididate to be considered for choice
if Best_So_Far = No_Unit_Id
or else ((not Pessimistic_Elab_Order)
and then Better_Choice (U, Best_So_Far))
or else (Pessimistic_Elab_Order
and then Pessimistic_Better_Choice (U, Best_So_Far))
then
if Debug_Flag_N then
Write_Str (" tentatively chosen (best so far)");
Write_Eol;
end if;
Best_So_Far := U;
end if;
U := UNR.Table (U).Nextnp;
exit No_Pred_Search when U = No_Unit_Id;
end loop No_Pred_Search;
-- If no candididate chosen, it means that no unit has No_Pred = 0,
-- but there are units left, hence we have a circular dependency,
-- which we will get Diagnose_Elaboration_Problem to diagnose it.
if Best_So_Far = No_Unit_Id then
Diagnose_Elaboration_Problem;
-- Otherwise choose the best candidate found
else
Choose (Best_So_Far);
end if;
end loop Outer;
end Find_Elab_Order;
-------------------------
-- Gather_Dependencies --
-------------------------
procedure Gather_Dependencies is
Withed_Unit : Unit_Id;
begin
-- Loop through all units
for U in Units.First .. Units.Last loop
Cur_Unit := U;
-- If this is not an interface to a stand-alone library and
-- there is a body and a spec, then spec must be elaborated first
-- Note that the corresponding spec immediately follows the body
if not Units.Table (U).SAL_Interface
and then Units.Table (U).Utype = Is_Body
then
Build_Link (Corresponding_Spec (U), U, Spec_First);
end if;
-- If this unit is not an interface to a stand-alone library,
-- process WITH references for this unit ignoring generic units and
-- interfaces to stand-alone libraries.
if not Units.Table (U).SAL_Interface then
for
W in Units.Table (U).First_With .. Units.Table (U).Last_With
loop
if Withs.Table (W).Sfile /= No_File
and then (not Withs.Table (W).SAL_Interface)
then
-- Check for special case of withing a unit that does not
-- exist any more. If the unit was completely missing we
-- would already have detected this, but a nasty case arises
-- when we have a subprogram body with no spec, and some
-- obsolete unit with's a previous (now disappeared) spec.
if Get_Name_Table_Info (Withs.Table (W).Uname) = 0 then
Error_Msg_File_1 := Units.Table (U).Sfile;
Error_Msg_Unit_1 := Withs.Table (W).Uname;
Error_Msg ("{ depends on $ which no longer exists");
goto Next_With;
end if;
Withed_Unit :=
Unit_Id (Unit_Id_Of (Withs.Table (W).Uname));
-- Pragma Elaborate_All case, for this we use the recursive
-- Elab_All_Links procedure to establish the links.
if Withs.Table (W).Elaborate_All then
-- Reset flags used to stop multiple visits to a given
-- node.
for Uref in UNR.First .. UNR.Last loop
UNR.Table (Uref).Visited := False;
end loop;
-- Now establish all the links we need
Elab_All_Links
(Withed_Unit, U, Elab_All,
Make_Elab_Entry
(Withs.Table (W).Uname, No_Elab_All_Link));
-- Elaborate_All_Desirable case, for this we establish the
-- same links as above, but with a different reason.
elsif Withs.Table (W).Elab_All_Desirable then
-- Reset flags used to stop multiple visits to a given
-- node.
for Uref in UNR.First .. UNR.Last loop
UNR.Table (Uref).Visited := False;
end loop;
-- Now establish all the links we need
Elab_All_Links
(Withed_Unit, U, Elab_All_Desirable,
Make_Elab_Entry
(Withs.Table (W).Uname, No_Elab_All_Link));
-- Pragma Elaborate case. We must build a link for the
-- withed unit itself, and also the corresponding body if
-- there is one.
-- However, skip this processing if there is no ALI file for
-- the WITH entry, because this means it is a generic (even
-- when we fix the generics so that an ALI file is present,
-- we probably still will have no ALI file for unchecked and
-- other special cases).
elsif Withs.Table (W).Elaborate
and then Withs.Table (W).Afile /= No_File
then
Build_Link (Withed_Unit, U, Withed);
if Units.Table (Withed_Unit).Utype = Is_Spec then
Build_Link
(Corresponding_Body (Withed_Unit), U, Elab);
end if;
-- Elaborate_Desirable case, for this we establish
-- the same links as above, but with a different reason.
elsif Withs.Table (W).Elab_Desirable then
Build_Link (Withed_Unit, U, Withed);
if Units.Table (Withed_Unit).Utype = Is_Spec then
Build_Link
(Corresponding_Body (Withed_Unit),
U, Elab_Desirable);
end if;
-- A limited_with does not establish an elaboration
-- dependence (that's the whole point!).
elsif Withs.Table (W).Limited_With then
null;
-- Case of normal WITH with no elaboration pragmas, just
-- build the single link to the directly referenced unit
else
Build_Link (Withed_Unit, U, Withed);
end if;
end if;
<<Next_With>>
null;
end loop;
end if;
end loop;
end Gather_Dependencies;
------------------
-- Is_Body_Unit --
------------------
function Is_Body_Unit (U : Unit_Id) return Boolean is
begin
return Units.Table (U).Utype = Is_Body
or else Units.Table (U).Utype = Is_Body_Only;
end Is_Body_Unit;
-----------------------------
-- Is_Pure_Or_Preelab_Unit --
-----------------------------
function Is_Pure_Or_Preelab_Unit (U : Unit_Id) return Boolean is
begin
-- If we have a body with separate spec, test flags on the spec
if Units.Table (U).Utype = Is_Body then
return Units.Table (U + 1).Preelab
or else
Units.Table (U + 1).Pure;
-- Otherwise we have a spec or body acting as spec, test flags on unit
else
return Units.Table (U).Preelab
or else
Units.Table (U).Pure;
end if;
end Is_Pure_Or_Preelab_Unit;
---------------------
-- Is_Waiting_Body --
---------------------
function Is_Waiting_Body (U : Unit_Id) return Boolean is
begin
return Units.Table (U).Utype = Is_Body
and then UNR.Table (Corresponding_Spec (U)).Elab_Position /= 0;
end Is_Waiting_Body;
---------------------
-- Make_Elab_Entry --
---------------------
function Make_Elab_Entry
(Unam : Unit_Name_Type;
Link : Elab_All_Id) return Elab_All_Id
is
begin
Elab_All_Entries.Increment_Last;
Elab_All_Entries.Table (Elab_All_Entries.Last).Needed_By := Unam;
Elab_All_Entries.Table (Elab_All_Entries.Last).Next_Elab := Link;
return Elab_All_Entries.Last;
end Make_Elab_Entry;
-------------------------------
-- Pessimistic_Better_Choice --
-------------------------------
function Pessimistic_Better_Choice (U1, U2 : Unit_Id) return Boolean is
UT1 : Unit_Record renames Units.Table (U1);
UT2 : Unit_Record renames Units.Table (U2);
begin
if Debug_Flag_B then
Write_Str ("Pessimistic_Better_Choice (");
Write_Unit_Name (UT1.Uname);
Write_Str (", ");
Write_Unit_Name (UT2.Uname);
Write_Line (")");
end if;
-- Note: the checks here are applied in sequence, and the ordering is
-- significant (i.e. the more important criteria are applied first).
-- If either unit is predefined or internal, then we use the normal
-- Better_Choice rule, since we don't want to disturb the elaboration
-- rules of the language with -p, same treatment for Pure/Preelab.
-- Prefer a predefined unit to a non-predefined unit
if UT1.Predefined and then not UT2.Predefined then
if Debug_Flag_B then
Write_Line (" True: u1 is predefined, u2 is not");
end if;
return True;
elsif UT2.Predefined and then not UT1.Predefined then
if Debug_Flag_B then
Write_Line (" False: u2 is predefined, u1 is not");
end if;
return False;
-- Prefer an internal unit to a non-internal unit
elsif UT1.Internal and then not UT2.Internal then
if Debug_Flag_B then
Write_Line (" True: u1 is internal, u2 is not");
end if;
return True;
elsif UT2.Internal and then not UT1.Internal then
if Debug_Flag_B then
Write_Line (" False: u2 is internal, u1 is not");
end if;
return False;
-- Prefer a pure or preelaborable unit to one that is not
elsif Is_Pure_Or_Preelab_Unit (U1)
and then not
Is_Pure_Or_Preelab_Unit (U2)
then
if Debug_Flag_B then
Write_Line (" True: u1 is pure/preelab, u2 is not");
end if;
return True;
elsif Is_Pure_Or_Preelab_Unit (U2)
and then not
Is_Pure_Or_Preelab_Unit (U1)
then
if Debug_Flag_B then
Write_Line (" False: u2 is pure/preelab, u1 is not");
end if;
return False;
-- Prefer anything else to a waiting body. We want to make bodies wait
-- as long as possible, till we are forced to choose them!
elsif Is_Waiting_Body (U1) and then not Is_Waiting_Body (U2) then
if Debug_Flag_B then
Write_Line (" False: u1 is waiting body, u2 is not");
end if;
return False;
elsif Is_Waiting_Body (U2) and then not Is_Waiting_Body (U1) then
if Debug_Flag_B then
Write_Line (" True: u2 is waiting body, u1 is not");
end if;
return True;
-- Prefer a spec to a body (!)
elsif Is_Body_Unit (U1) and then not Is_Body_Unit (U2) then
if Debug_Flag_B then
Write_Line (" False: u1 is body, u2 is not");
end if;
return False;
elsif Is_Body_Unit (U2) and then not Is_Body_Unit (U1) then
if Debug_Flag_B then
Write_Line (" True: u2 is body, u1 is not");
end if;
return True;
-- If both are waiting bodies, then prefer the one whose spec is
-- less recently elaborated. Consider the following:
-- spec of A
-- spec of B
-- body of A or B?
-- The normal waiting body preference would have placed the body of
-- A before the spec of B if it could. Since it could not, there it
-- must be the case that A depends on B. It is therefore a good idea
-- to put the body of B last so that if there is an elaboration order
-- problem, we will find it (that's what pssimistic order is about)
elsif Is_Waiting_Body (U1) and then Is_Waiting_Body (U2) then
declare
Result : constant Boolean :=
UNR.Table (Corresponding_Spec (U1)).Elab_Position <
UNR.Table (Corresponding_Spec (U2)).Elab_Position;
begin
if Debug_Flag_B then
if Result then
Write_Line (" True: based on waiting body elab positions");
else
Write_Line (" False: based on waiting body elab positions");
end if;
end if;
return Result;
end;
end if;
-- Remaining choice rules are disabled by Debug flag -do
if not Debug_Flag_O then
-- The following deal with the case of specs which have been marked
-- as Elaborate_Body_Desirable. In the normal case, we generally want
-- to delay the elaboration of these specs as long as possible, so
-- that bodies have better chance of being elaborated closer to the
-- specs. Pessimistic_Better_Choice as usual wants to do the opposite
-- and elaborate such specs as early as possible.
-- If we have two units, one of which is a spec for which this flag
-- is set, and the other is not, we normally prefer to delay the spec
-- for which the flag is set, so again Pessimistic_Better_Choice does
-- the opposite.
if not UT1.Elaborate_Body_Desirable
and then UT2.Elaborate_Body_Desirable
then
if Debug_Flag_B then
Write_Line (" False: u1 is elab body desirable, u2 is not");
end if;
return False;
elsif not UT2.Elaborate_Body_Desirable
and then UT1.Elaborate_Body_Desirable
then
if Debug_Flag_B then
Write_Line (" True: u1 is elab body desirable, u2 is not");
end if;
return True;
-- If we have two specs that are both marked as Elaborate_Body
-- desirable, we normally prefer the one whose body is nearer to
-- being able to be elaborated, based on the Num_Pred count. This
-- helps to ensure bodies are as close to specs as possible. As
-- usual, Pessimistic_Better_Choice does the opposite.
elsif UT1.Elaborate_Body_Desirable
and then UT2.Elaborate_Body_Desirable
then
declare
Result : constant Boolean :=
UNR.Table (Corresponding_Body (U1)).Num_Pred >=
UNR.Table (Corresponding_Body (U2)).Num_Pred;
begin
if Debug_Flag_B then
if Result then
Write_Line (" True based on Num_Pred compare");
else
Write_Line (" False based on Num_Pred compare");
end if;
end if;
return Result;
end;
end if;
end if;
-- If we fall through, it means that no preference rule applies, so we
-- use alphabetical order to at least give a deterministic result. Since
-- Pessimistic_Better_Choice is in the business of stirring up the
-- order, we will use reverse alphabetical ordering.
if Debug_Flag_B then
Write_Line (" choose on reverse alpha order");
end if;
return Uname_Less (UT2.Uname, UT1.Uname);
end Pessimistic_Better_Choice;
----------------
-- Unit_Id_Of --
----------------
function Unit_Id_Of (Uname : Unit_Name_Type) return Unit_Id is
Info : constant Int := Get_Name_Table_Info (Uname);
begin
pragma Assert (Info /= 0 and then Unit_Id (Info) /= No_Unit_Id);
return Unit_Id (Info);
end Unit_Id_Of;
------------------------
-- Write_Dependencies --
------------------------
procedure Write_Dependencies is
begin
if not Zero_Formatting then
Write_Eol;
Write_Str (" ELABORATION ORDER DEPENDENCIES");
Write_Eol;
Write_Eol;
end if;
Info_Prefix_Suppress := True;
for S in Succ_First .. Succ.Last loop
Elab_Error_Msg (S);
end loop;
Info_Prefix_Suppress := False;
if not Zero_Formatting then
Write_Eol;
end if;
end Write_Dependencies;
--------------------------
-- Write_Elab_All_Chain --
--------------------------
procedure Write_Elab_All_Chain (S : Successor_Id) is
ST : constant Successor_Link := Succ.Table (S);
After : constant Unit_Name_Type := Units.Table (ST.After).Uname;
L : Elab_All_Id;
Nam : Unit_Name_Type;
First_Name : Boolean := True;
begin
if ST.Reason in Elab_All .. Elab_All_Desirable then
L := ST.Elab_All_Link;
while L /= No_Elab_All_Link loop
Nam := Elab_All_Entries.Table (L).Needed_By;
Error_Msg_Unit_1 := Nam;
Error_Msg_Output (" $", Info => True);
Get_Name_String (Nam);
if Name_Buffer (Name_Len) = 'b' then
if First_Name then
Error_Msg_Output
(" must be elaborated along with its spec:",
Info => True);
else
Error_Msg_Output
(" which must be elaborated " &
"along with its spec:",
Info => True);
end if;
else
if First_Name then
Error_Msg_Output
(" is withed by:",
Info => True);
else
Error_Msg_Output
(" which is withed by:",
Info => True);
end if;
end if;
First_Name := False;
L := Elab_All_Entries.Table (L).Next_Elab;
end loop;
Error_Msg_Unit_1 := After;
Error_Msg_Output (" $", Info => True);
end if;
end Write_Elab_All_Chain;
end Binde;
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