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(Eval_Relational_Op): Use new Is_Known_Null flag to deal with case 

of null = null, now known true.

From-SVN: r111106
This commit is contained in:
Arnaud Charlet 2006-02-15 10:51:54 +01:00
parent 51c40324f3
commit 7a3f77d2a9
1 changed files with 29 additions and 28 deletions
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57
gcc/ada/sem_eval.adb
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@ -6,7 +6,7 @@
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2005, Free Software Foundation, Inc. --
-- Copyright (C) 1992-2006, 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- --
@ -2202,25 +2202,29 @@ package body Sem_Eval is
end if;
end;
-- Another special case: comparisons against null for pointers that
-- are known to be non-null. This is useful when migrating from Ada95
-- code when non-null restrictions are added to type declarations and
-- parameter specifications.
-- Another special case: comparisons of access types, where one or both
-- operands are known to be null, so the result can be determined.
elsif Is_Access_Type (Typ)
and then Comes_From_Source (N)
and then
((Is_Entity_Name (Left)
and then Is_Known_Non_Null (Entity (Left))
and then Nkind (Right) = N_Null)
or else
(Is_Entity_Name (Right)
and then Is_Known_Non_Null (Entity (Right))
and then Nkind (Left) = N_Null))
then
Fold_Uint (N, Test (Nkind (N) = N_Op_Ne), False);
Warn_On_Known_Condition (N);
return;
elsif Is_Access_Type (Typ) then
if Known_Null (Left) then
if Known_Null (Right) then
Fold_Uint (N, Test (Nkind (N) = N_Op_Eq), False);
Warn_On_Known_Condition (N);
return;
elsif Known_Non_Null (Right) then
Fold_Uint (N, Test (Nkind (N) = N_Op_Ne), False);
Warn_On_Known_Condition (N);
return;
end if;
elsif Known_Non_Null (Left) then
if Known_Null (Right) then
Fold_Uint (N, Test (Nkind (N) = N_Op_Ne), False);
Warn_On_Known_Condition (N);
return;
end if;
end if;
end if;
-- Can only fold if type is scalar (don't fold string ops)
@ -4014,13 +4018,8 @@ package body Sem_Eval is
elsif
Has_Unknown_Discriminants (T1) /= Has_Unknown_Discriminants (T2)
then
if Is_Generic_Actual_Type (T1)
and then Etype (T1) = T2
then
return True;
else
return False;
end if;
return
Is_Generic_Actual_Type (T1) or else Is_Generic_Actual_Type (T2);
-- Array type
@ -4060,11 +4059,13 @@ package body Sem_Eval is
if Can_Never_Be_Null (T1) /= Can_Never_Be_Null (T2) then
return False;
elsif Ekind (T1) = E_Access_Subprogram_Type then
elsif Ekind (T1) = E_Access_Subprogram_Type
or else Ekind (T1) = E_Anonymous_Access_Subprogram_Type
then
return
Subtype_Conformant
(Designated_Type (T1),
Designated_Type (T1));
Designated_Type (T2));
else
return
Subtypes_Statically_Match