When generating alignment checks for Address representation clauses we
optimized them away for clauses like:
for X'Address use Arr (1)'Address;
for X'Address use Rec.C'Address;
but not:
for X'Address use Obj'Address;
even though the alignment of Obj is known.
Tested on x86_64-pc-linux-gnu, committed on trunk
gcc/ada/
* sem_util.adb (Has_Compatible_Alignment_Internal): If the
prefix of the Address expression is an entire object with a
known alignment, then skip checks related to its size.diff --git a/gcc/ada/sem_util.adb b/gcc/ada/sem_util.adb
--- a/gcc/ada/sem_util.adb
+++ b/gcc/ada/sem_util.adb
@@ -11939,6 +11939,7 @@ package body Sem_Util is
elsif Is_Entity_Name (Expr)
and then Known_Alignment (Entity (Expr))
then
+ Offs := Uint_0;
ExpA := Alignment (Entity (Expr));
-- Otherwise, we can use the alignment of the type of Expr
@@ -11961,9 +11962,9 @@ package body Sem_Util is
Set_Result (Known_Incompatible);
end if;
- -- If Expr is not a piece of a larger object, see if size
- -- is given. If so, check that it is not too small for the
- -- required alignment.
+ -- If Expr is a component or an entire object with a known
+ -- alignment, then we are fine. Otherwise, if its size is
+ -- known, it must be big enough for the required alignment.
if Offs /= No_Uint then
null;
@@ -11982,7 +11983,7 @@ package body Sem_Util is
end if;
-- If we got a size, see if it is a multiple of the Obj
- -- alignment, if not, then the alignment cannot be
+ -- alignment; if not, then the alignment cannot be
-- acceptable, since the size is always a multiple of the
-- alignment.
