llvm dev - Apr 2015 - [LLVMdev] Code review for gather and scatter intrinsics

Hi,

I have a code ready,  waiting for review here: http://reviews.llvm.org/D7665.
I presented this work on LLVM Euro and people are interested in this feature.
Can anybody review this code, please?

Thanks.

-        Elena



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On 16 April 2015 at 14:44, Demikhovsky, Elena
<elena.demikhovsky at intel.com> wrote:
> http://reviews.llvm.org/D7665.
> I presented this work on LLVM Euro and people are interested in this
> feature.
> Can anybody review this code, please?
Hi Elena,

Sorry for the delay, I'm still catching up with my emails after a long
holiday. :)

The only concern to this feature I remember was Chandler's comment
that we should try to encode everything into loads and shuffles.

Correct me if I'm wrong, but on the strided vectorizer thread we have
reached a consensus that indexed intrinsics would be the least
problematic (compared to strided access intrinsics or plain
load+shuffle) because they're restricted to load/store of patterns
that could later be lowered to shuffles, if the hardware doesn't
support it, but they'd also keep the pattern intact even after other
optimization passes have gone through the same code.

Chandler,

As I said at EuroLLVM, the fear is that we'd get the pattern destroyed
and lose the ability of using masked / strided access at all. However,
I'm haven't looked at great depth at this problem to know what are the
cases and why they could break. Maybe Elena or James could help with
that.

cheers,
--renato

Hi Renato,

I fully agree with you, but indexed load and store is the next step. 
I'm asking to review gather and scatter code.

Thanks.

-  Elena

-----Original Message-----
From: Renato Golin [mailto:renato.golin at linaro.org] 
Sent: Thursday, April 16, 2015 17:17
To: Demikhovsky, Elena
Cc: llvmdev at cs.uiuc.edu; Chandler Carruth; James Molloy
Subject: Re: [LLVMdev] Code review for gather and scatter intrinsics

On 16 April 2015 at 14:44, Demikhovsky, Elena <elena.demikhovsky at
intel.com> wrote:
> http://reviews.llvm.org/D7665.
> I presented this work on LLVM Euro and people are interested in this 
> feature.
> Can anybody review this code, please?
Hi Elena,

Sorry for the delay, I'm still catching up with my emails after a long
holiday. :)

The only concern to this feature I remember was Chandler's comment that we
should try to encode everything into loads and shuffles.

Correct me if I'm wrong, but on the strided vectorizer thread we have
reached a consensus that indexed intrinsics would be the least problematic
(compared to strided access intrinsics or plain
load+shuffle) because they're restricted to load/store of patterns
that could later be lowered to shuffles, if the hardware doesn't support it,
but they'd also keep the pattern intact even after other optimization passes
have gone through the same code.

Chandler,

As I said at EuroLLVM, the fear is that we'd get the pattern destroyed and
lose the ability of using masked / strided access at all. However, I'm
haven't looked at great depth at this problem to know what are the cases and
why they could break. Maybe Elena or James could help with that.

cheers,
--renato
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Intel Israel (74) Limited

This e-mail and any attachments may contain confidential material for
the sole use of the intended recipient(s). Any review or distribution
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recipient, please contact the sender and delete all copies.