[llvm-dev] TypeExpandInteger for vectors?

[Sean Silva via llvm-dev]

Thanks Eli. Good idea of using DAG combines for this, I'll see if that
works for us.

-- Sean Silva

On Tue, Dec 12, 2017 at 12:22 PM, Friedman, Eli <efriedma at codeaurora.org>
wrote:

> On 12/12/2017 7:26 AM, Sean Silva via llvm-dev wrote:
>
>
>
> On Dec 11, 2017 6:54 PM, "Sean Silva" <chisophugis at gmail.com> wrote:
>
> It looks like in various places in SelectionDAG and related machinery we
> appear to implicitly or explicitly assume that TypeExpandInteger only
> applies to scalars.
>
> Does anybody know why that is?
>
> For our target (Pixel Visual Core: https://www.blog.google/
> products/pixel/pixel-visual-core-image-processing-and-machin
> e-learning-pixel-2/) expanding a N-bit vector op into two (N/2)-bit
> vector ops
>
>
> To be clear: the vector ops are all of the same number of elements. Just
> the bit width of the element type changes.
>
>
> I think it just hasn't been a priority for any in-tree target; most code
> doesn't use illegal vector types much, and the default strategy generates
> decent code in most cases.  (You might have an easier time just adding a
> few target-specific DAGCombines for specific operations which lead to
> low-quality code.)
>
> -Eli
>
> --
> Employee of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
>
>
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