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Re: Status of SSE builtins
- From: Richard Henderson <rth at redhat dot com>
- To: Jan Hubicka <jh at suse dot cz>
- Cc: Joern Rennecke <joern dot rennecke at superh dot com>, gcc at gcc dot gnu dot org, bernds at redhat dot com, aj at suse dot de
- Date: Thu, 31 Oct 2002 08:52:28 -0800
- Subject: Re: Status of SSE builtins
- References: <3DC04D9A.2D379818@superh.com> <20021030214140.GA22590@kam.mff.cuni.cz>
On Wed, Oct 30, 2002 at 10:41:40PM +0100, Jan Hubicka wrote:
> We generate instruction dealing with elements of the vector using
> subregs, like (subreg:HI (reg:V4HI) 2) is expected to access and modify
> only the second field of the vector. However the subregs gneerally
> clobber whole word in GCC and are not allowed in such general forms.
Yes, I was talking with Aldy about this recently. He has the
same problem for Motorola BookE vectors.
I think the proper solution is to have named patterns in the md file
that the rtl expander will use to satisfy these insertions and extractions.
If the named patterns do not exist, or FAIL, then we fall back to a
combination of subreg and insert/extract bitfield.
r~