[COMMITED] ada: Clean up slice-of-component optimization

["Marc Poulhiès" <poulhies@adacore.com>]

From: Bob Duff <duff@adacore.com>

In the recursive case of Volatile_Or_Independent = False for array
types, fall through into later checks, so for example we check
the type of the prefix of a slice. The pattern here is "return True
in certain cases, otherwise fall through into the final 'return False'".

Remove check for "Ndim = 1"; if Slices is True, then the number of
dimensions is necessarily 1, because Ada doesn't have multi-dimensional
slices.

gcc/ada/

	* exp_ch5.adb
	(Expand_Assign_Array_Loop_Or_Bitfield): Minor cleanups.

Tested on x86_64-pc-linux-gnu, committed on master.
---
 gcc/ada/exp_ch5.adb | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/gcc/ada/exp_ch5.adb b/gcc/ada/exp_ch5.adb
index 9669737a79b..d5d66d961de 100644
--- a/gcc/ada/exp_ch5.adb
+++ b/gcc/ada/exp_ch5.adb
@@ -1632,7 +1632,10 @@ package body Exp_Ch5 is
          end if;
 
          if Is_Array_Type (Typ) then
-            return Volatile_Or_Independent (Empty, Component_Type (Typ));
+            if Volatile_Or_Independent (Empty, Component_Type (Typ)) then
+               return True;
+            end if;
+
          elsif Is_Record_Type (Typ) then
             declare
                Comp : Entity_Id := First_Component (Typ);
@@ -1688,7 +1691,6 @@ package body Exp_Ch5 is
         and then Is_Bit_Packed_Array (R_Type)
         and then not Reverse_Storage_Order (L_Type)
         and then not Reverse_Storage_Order (R_Type)
-        and then Ndim = 1
         and then Slices
         and then not Slice_Of_Packed_Component (L)
         and then not Volatile_Or_Independent (L, L_Type)
-- 
2.34.1