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Subject: Re: V9 [PATCH] C/C++: Add -Waddress-of-packed-member
To: "H.J. Lu" <hjl.tools@gmail.com>, Sandra Loosemore <sandra@codesourcery.com>
Cc: Richard Guenther <richard.guenther@gmail.com>, "Joseph S. Myers" <joseph@codesourcery.com>, Martin Sebor <msebor@gmail.com>, GCC Patches <gcc-patches@gcc.gnu.org>
References: <CAMe9rOohUOR+eta2gvwNxbjMR1y=P=vA3+Sniaj_tS03qamj6g@mail.gmail.com> <d3a6bf60-4c66-54d7-b159-a6f6b5ecfdbe@redhat.com> <CAMe9rOq67grqBtdDL7YQdAwGp+9KAqiuQbs_gyiXdemNoX19Ng@mail.gmail.com> <24f8a201-bb3e-3acb-b679-570a8796358d@redhat.com> <CAMe9rOo1hsE9pMC5DV1t0LJ0xkKhdX7TACf1_pZpYmxaNgZMPA@mail.gmail.com> <CAFiYyc2JrHbXA5QNuXqyRzccnzwf9iduSZBJBw8A_fOSMHMPaw@mail.gmail.com> <CAMe9rOq93B0tO_SkJ=aPP4rYfDG8pf4+_-7WhKy60mn5PCrEZw@mail.gmail.com> <bd7ff807-0918-9d66-8043-969d4d2ff8b0@redhat.com> <20181218141051.GA3461@gmail.com> <14946d45-0983-12ad-3f93-99da07b3886e@redhat.com> <CAMe9rOq-_k1ntkAxbDCKY=OdFrzdS+Z6b_MZdVOwWRTFCP4_Mg@mail.gmail.com> <7f0ae96e-87b8-5db9-97b5-90094c4dace7@redhat.com> <CAMe9rOq+Smwo+LWTE=ygPH0kMOCdTYNh9FOHWoWSjJv4g=ccNw@mail.gmail.com> <CAMe9rOomWf5=+_mtgqNdTwq2V3uSgStcraLX57Nc-uLJsyvO=A@mail.gmail.com>
From: Jason Merrill <jason@redhat.com>
Message-ID: <63472b60-a401-5c43-de38-87187cdc95c5@redhat.com>
Date: Thu, 20 Dec 2018 19:40:00 -0000
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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