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Re: (R5900) Implementing Vector Support
- From: Woon yung Liu <ysai187 at yahoo dot com>
- To: Richard Henderson <rth at redhat dot com>, Gcc Mailing List <gcc at gcc dot gnu dot org>
- Date: Fri, 3 Jun 2016 12:54:00 +0000 (UTC)
- Subject: Re: (R5900) Implementing Vector Support
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- Reply-to: Woon yung Liu <ysai187 at yahoo dot com>
On Wednesday, June 1, 2016 5:45 AM, Richard Henderson <email@example.com> wrote:
> This is almost always incorrect, and certainly before reload.
> You need to use gen_lowpart. There are examples in the code
> fragments that I sent the other week.
The problem is that gen_lowpart() doesn't seem to support casting to other modes of the same size.
When I use it, the assert within gen_lowpart_general() will fail due to gen_lowpart_common() rejecting the operation (new mode size is not smaller than the old).
> You need to read the gcc internals documentation. They are all three different
> uses, though there is some overlap between define_insn and define_expand.
I actually read the GCC internals documentation before I even begun any attempt at this, but there was still a lot that I did not successfully grasp.
I'll go with define_expand then.
But I am already doubting that I will complete this port as I can no longer see a favourable conclusion.
Thanks and regards,