[llvm-dev] Clang 5.0 support for armv8 64 bit with neon and auto vectorization

[Peter Smith via llvm-dev]

Hello Haider,

I'll have to make this quick as I need to leave the office to get on a
train. I hope my colleagues will be able to correct anything I've got
wrong.

I suggest taking a look at the set of command line options supported
by the aarch64 target. The armv8 target can mean m-profile without
ARM, r-profile or a-profile, floating point or neon is not uniform
across these targets.

For -target=aarch64 simd and hard precision floating point are the
default and assumed option, there is also no ABI support for
soft-floating point so the command line options are redundant. I
suggest just removing -mfpu and -mfloat-abi and you'll get the results
you want.

The -march and -mcpu options can give you some extra control, for
example --target=aarch64 -march=armv8-a+simd+fp.

Peter



On 3 February 2017 at 08:48, Haider Zeeshan (CC/ESM1) via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> Hi there,
>
>
>
> I am Software product developer at Robert Bosch, Germany.
>
>
>
> We are using armv8 64bit targets for our development. We have the need to do
> the cross compiling for our target on windows. I have compiled clang 5.0
> from the vcs git. I have tried compiling the code with following options
> set:
>
>
>
> clang.exe -target armv8 -fslp-vectorize-aggressive  -mfpu=neon
> -mfloat-abi=hard -c test.cpp
>
>
>
> As you can see in the options, we require neon feature as well as auto
> vectorizations on armv8 (64 bit). Can you tell me that is it true that clang
> supports neon and auto vectorizations with 64bit arm v8 architecture?
>
>
>
> This setting says that neon is not in support, Can you explain why? As of my
> understanding, arm v8 is a 64 bit architecture!
>
> clang.exe -target arm64 -fslp-vectorize-aggressive  -mfpu=neon
> -mfloat-abi=hard -c test.cpp
>
>
>
>
>
> Mit freundlichen Grüßen / Best regards
>
> Zeeshan Haider
>
>
>
> Chassis Systems Control, Engineering Software Coordination, Software
> Mainstream Management, Methods Group 1 (CC/ESM1)
>
> Robert Bosch GmbH | Postfach 16 61 | 71226 Leonberg | GERMANY |
> www.bosch.com
>
> Tel. +49(711)811-47379 | Fax +49(711)811-0 | Zeeshan.Haider at de.bosch.com
>
>
>
> Sitz: Stuttgart, Registergericht: Amtsgericht Stuttgart, HRB 14000;
>
> Aufsichtsratsvorsitzender: Franz Fehrenbach; Geschäftsführung: Dr. Volkmar
> Denner,
>
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> Markus Heyn, Dr. Dirk Hoheisel,
>
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