[llvm] r342870 - [ARM] bottom-top mul support ARMParallelDSP

[Sam Parker via llvm-commits]

Thanks Eli, certainly looks like something it could break. I will hopefully get a fix up today.


Sam Parker

Compilation Tools Engineer | Arm

. . . . . . . . . . . . . . . . . . . . . . . . . . .

Arm.com

________________________________
From: Friedman, Eli <efriedma at codeaurora.org>
Sent: 25 September 2018 20:02:27
To: Sam Parker; llvm-commits at lists.llvm.org
Subject: Re: [llvm] r342870 - [ARM] bottom-top mul support ARMParallelDSP

On 9/24/2018 2:34 AM, Sam Parker via llvm-commits wrote:
> Author: sam_parker
> Date: Mon Sep 24 02:34:06 2018
> New Revision: 342870
>
> URL: http://llvm.org/viewvc/llvm-project?rev=342870&view=rev
> Log:
> [ARM] bottom-top mul support ARMParallelDSP
>
> Originally committed in rL342210 but was reverted in rL342260 because
> it was causing issues in vectorized code, because I had forgotten to
> ensure that we're operating on scalar values.
>
> Original commit message:
>
> On failing to find sequences that can be converted into dual macs,
> try to find sequential 16-bit loads that are used by muls which we
> can then use smultb, smulbt, smultt with a wide load.
>
> Differential Revision: https://reviews.llvm.org/D51983

It looks like this is causing the polly-aosp buildbot
(http://lab.llvm.org:8011/builders/aosp-O3-polly-before-vectorizer-unprofitable)
to fail.  Attached reduced testcase; reproduce with "llc
aosp-convolve-crash.bc".

-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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