[COMMITTED] ada: Do not count comparison of addresses as a modification

[COMMITTED] ada: Do not count comparison of addresses as a modification

[Marc Poulhiès]

From: Viljar Indus <indus@adacore.com>

In some extended code we generate comparisons between
the Addresses of some variables. This causes those
variables to be considered modified. Whereas in this
particular scenario the variables are just referenced.

gcc/ada/

	* sem_attr.adb: avoid marking a use of the Address attribute
	as a modification of its prefix.

Tested on x86_64-pc-linux-gnu, committed on master.

---
 gcc/ada/sem_attr.adb | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/gcc/ada/sem_attr.adb b/gcc/ada/sem_attr.adb
index a194360a601..f52103f28dd 100644
--- a/gcc/ada/sem_attr.adb
+++ b/gcc/ada/sem_attr.adb
@@ -12133,9 +12133,13 @@ package body Sem_Attr is
             | Attribute_Code_Address
          =>
             --  To be safe, assume that if the address of a variable is taken,
-            --  it may be modified via this address, so note modification.
+            --  it may be modified via this address, so note modification,
+            --  unless the address is compared directly, which should not be
+            --  considered a modification.
 
-            if Is_Variable (P) then
+            if Is_Variable (P)
+              and then Nkind (Parent (N)) not in N_Op_Compare
+            then
                Note_Possible_Modification (P, Sure => False);
             end if;
 
-- 
2.43.0