llvm-toolchain-3.8/3.9: armhf: defaults to emitting NEON instructions

[Paul Wise]

Control: clone -1 -2 -3
Control: reassign -2 src:llvm-toolchain-3.8
Control: retitle -2 llvm-toolchain-3.8: armhf: defaults to emitting NEON instructions
Control: reassign -3 src:llvm-toolchain-3.9
Control: retitle -3 llvm-toolchain-3.9: armhf: defaults to emitting NEON instructions
Control: block -1 by -3

Debian LLVM team: LLVM 3.8/3.9 default to emitting NEON instructions on
armhf but it is optional in ARMv7 so LLVM is producing binaries that do
not work on ARMv7 CPUs that lack NEON. This is causing build failures
in packages that use LLVM on Debian buildds that lack NEON.

On Wed, 26 Oct 2016 17:49:31 +0800 Paul Wise wrote:

> I've confirmed that the package builds fine on abel with llvm 3.7 after
> hardcoding clang 3.7 and updating DEB_BUILD_MAINT_OPTIONS to include
> reproducible=-fixdebugpath since clang doesn't know that option.
> 
> In addition, readelf -a prints a NEON flag for binaries produced by
> llvm 3.8 and 3.9 but not for llvm 3.7. According to unixsmurf on
> #debian-arm, llvm will set the flag for instructions binaries might
> contain, even if it hasn't happened to generate any.
> 
> Tag_Advanced_SIMD_arch: NEONv1

Daniel, for AFL, you may want to downgrade to llvm 3.7 on armhf for now.

-- 
bye,
pabs

https://wiki.debian.org/PaulWise
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