[llvm] r219084 - X86: Don't drop half of the mask when converting 2-address shufps into 3-address pshufd.

[Chandler Carruth]

On Sun, Oct 5, 2014 at 9:14 AM, Benjamin Kramer <benny.kra at googlemail.com>
wrote:

> Author: d0k
> Date: Sun Oct  5 11:14:29 2014
> New Revision: 219084
>
> URL: http://llvm.org/viewvc/llvm-project?rev=219084&view=rev
> Log:
> X86: Don't drop half of the mask when converting 2-address shufps into
> 3-address pshufd.
>
> It's debatable whether this transform is useful at all, but for now make
> sure
> we don't generate invalid asm.
>

Thanks for the fix, but I don't think it is even debatable. Trading a copy
for a domain cross seems like a very, very bad trade. I've removed this
optimization in r219090.
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