[PATCH] Add new indexed load/store intrinsics.

[Demikhovsky, Elena]

We are interested in these intrinsics anyway:

<4 x double> @llvm.masked.indexed.load.v4f64 (double* <ptr>, <4 x i32> <index>, i32 <alignment>, <4 x i1>%mask, <4 x double>%paththru)

Presence of index means that the sequential load is not a solution.
If you are not going to implement this interface now, I’ll do this later.


-           Elena

From: Renato Golin [mailto:renato.golin at linaro.org]
Sent: Thursday, April 23, 2015 10:29
To: reviews+D9194+public+a2f9c543cd08afc3 at reviews.llvm.org
Cc: Ahmed Bougacha; Hao.Liu at arm.com; llvm-commits at cs.uiuc.edu; qcolombet at apple.com; Demikhovsky, Elena
Subject: Re: [PATCH] Add new indexed load/store intrinsics.


On 23 Apr 2015 3:38 am, "Hao Liu" <Hao.Liu at arm.com<mailto:Hao.Liu at arm.com>> wrote:
>
> Hi Renato and Ahmed,
>
> I agree with your comments.
>
> But I want to change the plan. Because I think maybe there is no need to use intrinsics.
> For the interleaved load about <4 x double>
>
>   <4 x double> @llvm.indexed.load.v4f64 (double* <ptr>, <4 x i32> <index>, i32 <alignment>)
>
> I think we can use two common IRs:
>
>   <value> = load <4 x double>, <4 x double>* <ptr>
>   shufflevector <4 x double> <value>, <4 x double> undef, <4 x i32> <0, 2, 1, 3>
>
> Even though it is more complex for a backend to match two IRs, it is achievable. I think the disadvantage of  intrinsics is not easy to be optimized.
>
> I want to implement the loop vectorization on interleaved memory access  with vectorload/vectorstore+shufflevector.
>
> What do you think?

I agree. If it's possible to represent it in plain IR, I see no reason to not do it.

I'll be particularly interested in how other passes scramble the accesses, making the pattern irrecoverable. But I guess will find that out as you progress with the examples and tests.

Cheers,
Renato
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