[gcc r13-5204] ada: Lift restriction on optimization of aliased objects

[gcc r13-5204] ada: Lift restriction on optimization of aliased objects

[Marc Poulhi?s]

https://gcc.gnu.org/g:24993939b7e405cdb8fa7ab6b388913a5d9fb6ce

commit r13-5204-g24993939b7e405cdb8fa7ab6b388913a5d9fb6ce
Author: Eric Botcazou <ebotcazou@adacore.com>
Date:   Mon Jan 2 23:11:21 2023 +0100

    ada: Lift restriction on optimization of aliased objects
    
    It turns out that the only blocking case is an aliased object whose nominal
    subtype is an unconstrained array because the bounds must be allocated.
    
    gcc/ada/
    
            * exp_ch3.adb (Expand_N_Object_Declaration): Also optimize aliased
            objects if their nominal subtype is not an unconstrained array.

Diff:
---
 gcc/ada/exp_ch3.adb | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/gcc/ada/exp_ch3.adb b/gcc/ada/exp_ch3.adb
index 536ae0c36e4..c866a9c40f5 100644
--- a/gcc/ada/exp_ch3.adb
+++ b/gcc/ada/exp_ch3.adb
@@ -7965,10 +7965,10 @@ package body Exp_Ch3 is
 
               Is_Entity_Name (Original_Node (Obj_Def))
 
-                --  The aliased case has to be excluded because the expression
-                --  will not be aliased in the general case.
+                --  Nor if it is effectively an unconstrained declaration
 
-                and then not Aliased_Present (N)
+                and then not (Is_Array_Type (Typ)
+                               and then Is_Constr_Subt_For_UN_Aliased (Typ))
 
                 --  We may use a renaming if the initializing expression is a
                 --  captured function call that meets a few conditions.