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

[Hans Wennborg via llvm-commits]

It also broke Chromium's Android builds. See
https://bugs.chromium.org/p/chromium/issues/detail?id=889390#c2 for
repro.

I've reverted in r343082.

On Wed, Sep 26, 2018 at 8:53 AM, Sam Parker via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> 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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