This is the mail archive of the mailing list for the GCC project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: (R5900) Implementing Vector Support

Hi again,

On Wednesday, June 1, 2016 5:45 AM, Richard Henderson <> 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,
-W Y

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]