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.

3 files changed, 45 insertions, 11 deletions

diff --git a/gcc/config/arm/arm.cc b/gcc/config/arm/arm.cc
index 2eb4d51..b587561 100644
--- a/gcc/config/arm/arm.cc
+++ b/gcc/config/arm/arm.cc
@@ -375,7 +375,7 @@ static const struct attribute_spec arm_attribute_table[] =
   /* ARMv8-M Security Extensions support.  */
   { "cmse_nonsecure_entry", 0, 0, true, false, false, false,
     arm_handle_cmse_nonsecure_entry, NULL },
-  { "cmse_nonsecure_call", 0, 0, true, false, false, true,
+  { "cmse_nonsecure_call", 0, 0, false, false, false, true,
     arm_handle_cmse_nonsecure_call, NULL },
   { "Advanced SIMD type", 1, 1, false, true, false, true, NULL, NULL },
   { NULL, 0, 0, false, false, false, false, NULL, NULL }
@@ -7605,8 +7605,8 @@ arm_handle_cmse_nonsecure_call (tree *node, tree name,
 				 int /* flags */,
 				 bool *no_add_attrs)
 {
-  tree decl = NULL_TREE, fntype = NULL_TREE;
-  tree type;
+  tree decl = NULL_TREE;
+  tree fntype, type;
 
   if (!use_cmse)
     {
@@ -7616,16 +7616,20 @@ arm_handle_cmse_nonsecure_call (tree *node, tree name,
       return NULL_TREE;
     }
 
-  if (TREE_CODE (*node) == VAR_DECL || TREE_CODE (*node) == TYPE_DECL)
+  if (DECL_P (*node))
     {
-      decl = *node;
-      fntype = TREE_TYPE (decl);
+      fntype = TREE_TYPE (*node);
+
+      if (TREE_CODE (*node) == VAR_DECL || TREE_CODE (*node) == TYPE_DECL)
+	decl = *node;
     }
+  else
+    fntype = *node;
 
-  while (fntype != NULL_TREE && TREE_CODE (fntype) == POINTER_TYPE)
+  while (fntype && TREE_CODE (fntype) == POINTER_TYPE)
     fntype = TREE_TYPE (fntype);
 
-  if (!decl || TREE_CODE (fntype) != FUNCTION_TYPE)
+  if ((DECL_P (*node) && !decl) || TREE_CODE (fntype) != FUNCTION_TYPE)
     {
 	warning (OPT_Wattributes, "%qE attribute only applies to base type of a "
 		 "function pointer", name);
@@ -7640,10 +7644,17 @@ arm_handle_cmse_nonsecure_call (tree *node, tree name,
 
   /* Prevent trees being shared among function types with and without
      cmse_nonsecure_call attribute.  */
-  type = TREE_TYPE (decl);
+  if (decl)
+    {
+      type = build_distinct_type_copy (TREE_TYPE (decl));
+      TREE_TYPE (decl) = type;
+    }
+  else
+    {
+      type = build_distinct_type_copy (*node);
+      *node = type;
+    }
 
-  type = build_distinct_type_copy (type);
-  TREE_TYPE (decl) = type;
   fntype = type;
 
   while (TREE_CODE (fntype) != FUNCTION_TYPE)
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;