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

Haider Zeeshan (CC/ESM1) via llvm-dev llvm-dev at lists.llvm.org
Fri Feb 3 07:13:10 PST 2017

Thanks Peter and Tim.

Being that said, can I be sure that for 64 bit arm architectures (e.g. arm cortex A57) the  neon feature and auto-vectorization is supported as default by clang 5.0?

Because for us these two features are deal breaking for compiler evaluation.

Mit freundlichen Grüßen / Best regards 

Zeeshan Haider

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-----Original Message-----
From: Tim Northover [mailto:t.p.northover at gmail.com] 
Sent: Freitag, 3. Februar 2017 16:02
To: Haider Zeeshan (CC/ESM1) <Zeeshan.Haider at de.bosch.com>
Cc: llvm-dev at lists.llvm.org
Subject: Re: [llvm-dev] Clang 5.0 support for armv8 64 bit with neon and auto vectorization

On 3 February 2017 at 00:48, Haider Zeeshan (CC/ESM1) via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> clang.exe -target armv8 -fslp-vectorize-aggressive  -mfpu=neon 
> -mfloat-abi=hard -c test.cpp

Peter's advice is good (-mfpu and -mfloat-abi aren't needed). But also note that "-target armv8" actually targets 32-bit ARM (v8 CPUs usually support both modes).

You probably want to specify a full triple for the target, maybe "-target aarch64-linux-gnu", otherwise the OS part might default to Windows since that's where you're running. Clang doesnn't support Windows on AArch64.



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