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[Ada] Unnesting: fix for constrained arrays and improve static constants

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2018-12-11  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* exp_unst.adb (Needs_Fat_Pointer): A fat pointer is required if
	the entity has a private type whose full view is an
	unconstrained array type.
	(Rewrite_One_Ref): If the reference is to a static constant, use
	its value rather than create a reference through the activation
	record. This is more efficient, and furthermore indispensable if
	the context requires a static constant, such as in a branch of a
	case statement.

From-SVN: r267003
This commit is contained in:
Ed Schonberg 2018-12-11 11:11:22 +00:00 committed by Pierre-Marie de Rodat
parent 0a4578b6c6
commit 1d499c15a8
2 changed files with 38 additions and 3 deletions
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11
gcc/ada/ChangeLog
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@ -1,3 +1,14 @@
2018-12-11 Ed Schonberg <schonberg@adacore.com>
* exp_unst.adb (Needs_Fat_Pointer): A fat pointer is required if
the entity has a private type whose full view is an
unconstrained array type.
(Rewrite_One_Ref): If the reference is to a static constant, use
its value rather than create a reference through the activation
record. This is more efficient, and furthermore indispensable if
the context requires a static constant, such as in a branch of a
case statement.
2018-12-11 Ed Schonberg <schonberg@adacore.com>
* sem_ch3.adb (Analyze_Object_Declaration): Apply

30
gcc/ada/exp_unst.adb
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@ -246,10 +246,19 @@ package body Exp_Unst is
-----------------------
function Needs_Fat_Pointer (E : Entity_Id) return Boolean is
Typ : Entity_Id;
begin
return Is_Formal (E)
and then Is_Array_Type (Etype (E))
and then not Is_Constrained (Etype (E));
if Is_Formal (E) then
Typ := Etype (E);
if Is_Private_Type (Typ) and then Present (Full_View (Typ)) then
Typ := Full_View (Typ);
end if;
return Is_Array_Type (Typ)
and then not Is_Constrained (Typ);
else
return False;
end if;
end Needs_Fat_Pointer;
----------------
@ -2168,6 +2177,21 @@ package body Exp_Unst is
goto Continue;
end if;
-- If this is a reference to a global constant, use its value
-- rather than create a reference. It is more efficient and
-- furthermore indispensable if the context requires a
-- constant, such as a branch of a case statement.
if Ekind (UPJ.Ent) = E_Constant
and then Is_True_Constant (UPJ.Ent)
and then Present (Constant_Value (UPJ.Ent))
and then Is_Static_Expression (Constant_Value (UPJ.Ent))
then
Rewrite (UPJ.Ref,
New_Copy_Tree (Constant_Value (UPJ.Ent)));
goto Continue;
end if;
-- Push the current scope, so that the pointer type Tnn, and
-- any subsidiary entities resulting from the analysis of the
-- rewritten reference, go in the right entity chain.