Re: V10 [PATCH] C/C++: Add -Waddress-of-packed-member

[Jason Merrill]

On 12/20/18 2:52 PM, H.J. Lu wrote:

On Thu, Dec 20, 2018 at 11:28 AM Jason Merrill <ja...@redhat.com> wrote:

On 12/19/18 12:35 PM, H.J. Lu wrote:

+  while (handled_component_p (rhs))
+    {
+      if (TREE_CODE (rhs) == COMPONENT_REF)
+     break;
+      rhs = TREE_OPERAND (rhs, 0);
+    }
+
+  if (TREE_CODE (rhs) != COMPONENT_REF)
+    return NULL_TREE;
+
+  object = TREE_OPERAND (rhs, 0);
+  field = TREE_OPERAND (rhs, 1);
+
+  tree context = check_alignment_of_packed_member (type, field);
+  if (context)
+    return context;

All the above looks unnecessary; it will be handled by the loop below.

+  /* Check alignment of the object.  */
+  while (handled_component_p (object))
+    {
+      if (TREE_CODE (object) == COMPONENT_REF)
+     {
+       do
+         {
+           field = TREE_OPERAND (object, 1);
+           context = check_alignment_of_packed_member (type, field);
+           if (context)
+             return context;
+           object = TREE_OPERAND (object, 0);
+         }
+       while (TREE_CODE (object) == COMPONENT_REF);

This inner loop also seems unnecessary.

+     }
+      else
+     object = TREE_OPERAND (object, 0);
+    }

Jason

I changed it to

static tree
check_address_of_packed_member (tree type, tree rhs)
{
   if (INDIRECT_REF_P (rhs))
     rhs = TREE_OPERAND (rhs, 0);

   if (TREE_CODE (rhs) == ADDR_EXPR)
     rhs = TREE_OPERAND (rhs, 0);

   tree context = NULL_TREE;

   /* Check alignment of the object.  */
   while (handled_component_p (rhs))
     {
       if (TREE_CODE (rhs) == COMPONENT_REF)
         {
           tree field = TREE_OPERAND (rhs, 1);
           context = check_alignment_of_packed_member (type, field);
           if (context)
             break;
         }
       rhs = TREE_OPERAND (rhs, 0);
     }

   return context;
}

Here is the updated patch.  OK for trunk?

OK.

Jason