Make ARMv8-M attribute cmse_nonsecure_call work in Ada

Unlike most other machine attributes, this one does not work in Ada because,
while it applies to pointer-to-function types, it is explicitly marked as
requiring declarations in the implementation.

Now, in Ada, machine attributes are specified like this:

  type Non_Secure is access procedure;
  pragma Machine_Attribute (Non_Secure, "cmse_nonsecure_call");

i.e. not attached to the declaration of Non_Secure.

The change extends the support to Ada by also accepting pointer-to-function
types in the handler.

gcc/
	* config/arm/arm.cc (arm_attribute_table) <cmse_nonsecure_call>:
	Change decl_required field to false.
	(arm_handle_cmse_nonsecure_call): Deal with a TYPE node.

gcc/testsuite/
	* gnat.dg/machine_attr2.ads, gnat.dg/machine_attr2.adb: New test.

2 files changed, 23 insertions, 0 deletions

diff --git a/gcc/testsuite/gnat.dg/machine_attr2.adb b/gcc/testsuite/gnat.dg/machine_attr2.adb
new file mode 100644
index 0000000..e98a69a
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/machine_attr2.adb
@@ -0,0 +1,15 @@
+-- { dg-do compile { target arm*-*-* } }
+-- { dg-options "-mcpu=cortex-m33 -mcmse" }
+
+package body Machine_Attr2 is
+  
+  procedure Call (Proc : Non_Secure) is
+  begin
+    Proc.all;
+  end;
+
+  procedure Foo; -- { dg-warning "only applies to base type" }
+  pragma Machine_Attribute (Foo, "cmse_nonsecure_call");
+  procedure Foo is null;
+
+end Machine_Attr2;
diff --git a/gcc/testsuite/gnat.dg/machine_attr2.ads b/gcc/testsuite/gnat.dg/machine_attr2.ads
new file mode 100644
index 0000000..4eda09e
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/machine_attr2.ads
@@ -0,0 +1,8 @@
+package Machine_Attr2 is
+
+  type Non_Secure is access procedure;
+  pragma Machine_Attribute (Non_Secure, "cmse_nonsecure_call");
+
+  procedure Call (Proc : Non_Secure);
+
+end Machine_Attr2;