Fix wrong array type conversion with different storage orde

When two arrays of scalars have a different storage order in Ada, the
front-end makes sure that the conversion is performed component-wise
so that each component can be reversed.  So it's a little bit counter
productive that the ldist pass performs the opposite transformation
and synthesizes a memcpy/memmove in this case.

gcc/
	* tree-loop-distribution.cc (loop_distribution::classify_builtin_ldst):
	Bail out if source and destination do not have the same storage order.

gcc/testsuite/
	* gnat.dg/sso18.adb: New test.

1 files changed, 21 insertions, 0 deletions

diff --git a/gcc/testsuite/gnat.dg/sso18.adb b/gcc/testsuite/gnat.dg/sso18.adb
new file mode 100644
index 0000000..7496e96
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/sso18.adb
@@ -0,0 +1,21 @@
+--  { dg-do run }
+--  { dg-options "-O2" }
+
+with System;
+
+procedure SSO18 is
+
+  type Arr is array (1..32) of Short_Integer;
+  type Rev_Arr is array (1..32) of Short_Integer
+    with Scalar_Storage_Order => System.High_Order_First;
+  C : constant Arr := (others => 16);
+  RA : Rev_Arr;
+  A  : Arr;
+
+begin
+  RA := Rev_Arr(C);
+  A := Arr (RA);
+  if A /= C or else RA(1) /= 16 then
+     raise Program_Error;
+  end if;
+end;