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Re: mem operator with unspecified width
- To: Stephen Clarke <Stephen dot Clarke at st dot com>
- Subject: Re: mem operator with unspecified width
- From: Richard Henderson <rth at redhat dot com>
- Date: Wed, 15 Aug 2001 16:04:52 -0700
- Cc: gcc at gcc dot gnu dot org
- References: <3B7ACB60.95E6A303@st.com>
On Wed, Aug 15, 2001 at 12:20:00PM -0700, Stephen Clarke wrote:
> Is it legal in RTL for a mem operator to have unspecified width?
Yes, but ...
> (insn 56 55 58 (set (reg:DI 169)
> (mem (unspec[
... this is illegal. Unspecified width is BLKmode, not VOIDmode.
Additionally, the modes of source and destination must match. The
only object that is allowed to be VOIDmode is an integer constant.
You certainly want this mem to be Pmode, since this is a casesi pattern.
Note that unlike previous versions, gcc 3.1 allows Pmode in md patterns.