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Re: Unaligned block moves and MEM_ALIGN re-broken
- From: law at redhat dot com
- To: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- Cc: dje at watson dot ibm dot com, gcc at gcc dot gnu dot org
- Date: Fri, 25 Jan 2002 13:14:29 -0700
- Subject: Re: Unaligned block moves and MEM_ALIGN re-broken
- Reply-to: law at redhat dot com
In message <10201252000.AA13924@vlsi1.ultra.nyu.edu>, Richard Kenner writes:
> We do indeed require that an object of an integral mode be at an alignment
> defined by GET_MODE_ALIGNMENT.
>
> The only time when this isn't true is when STRICT_ALIGNMENT is not defined.
> but in that case, why does the alignment matter?
But STRICT_ALIGNMENT means that all objects must be on a natural
alignment boundary. The lack of STRICT_ALIGNMENT does _NOT_ mean that
data can be access irrespective of alignment concerns.
It's perfectly legitimate and normal for some alignment to be necessary on
a target without STRICT_ALIGNMENT. For example, a DFmode item may need to
have a 32bit alignment on a target without STRICT_ALIGNMENT.
jeff