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RE: [PATCH] Don't check for optab for 16bit bswap
- From: "Thomas Preud'homme" <thomas dot preudhomme at arm dot com>
- To: "'Richard Biener'" <rguenther at suse dot de>
- Cc: <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 29 Dec 2014 17:53:14 -0000
- Subject: RE: [PATCH] Don't check for optab for 16bit bswap
- Authentication-results: sourceware.org; auth=none
- References: <000401d02370$6167b440$24371cc0$ at arm dot com> <FCA0702A-77A7-4DFC-A504-F45C515B4538 at suse dot de>
> From: Richard Biener [mailto:rguenther@suse.de]
> Sent: Monday, December 29, 2014 5:09 PM
>
> OK, but what about targets without a rotation optab? Is the fallback
> expansion reasonable in all cases?
To be honest I haven't checked. I thought being a treecode means it
can always be expanded, using a sequence of shift and bitwise or if
necessary. Isn't there some language that GCC support with rotate
operators?
Given your question I guess I was wrong assuming this. Is there a list
of gimple construct that are necessary supported? What about a list
of insn pattern that a backend must necessarily provide?
Best regards,
Thomas