[pulseaudio-discuss] [PATCH webrtc-audio-processing] configure.ac: fix architecture detection

[Arun Raghavan]

On Sat, 6 Aug 2016, at 02:32 PM, Thomas Petazzoni wrote:
> The current architecture detection, based on the "host_cpu" part of the
> tuple does not work properly for a number of reason:
> 
>  - The code assumes that if host_cpu starts with "arm" then ARM
>    instructions are available, which is incorrect. Indeed, Cortex-M
>    platforms can run Linux, they are ARM platforms (so host_cpu = arm),
>    but they don't support ARM instructions: they support only the
>    Thumb-2 instruction set.
> 
>  - The armv7 case is also not very useful, as it is not standard at all
>    to pass armv7 as host_cpu even if the host system is actually ARMv7
>    based.
> 
>  - For the same reason, the armv8 case is not very useful: ARMv8 is
>    AArch64, and there is already a separate case to handle this
>    architecture.
> 
> So, this commit moves away from a host_cpu based logic, and instead
> tests using AC_CHECK_DECLS() the built-in definitions of the compiler:
> 
>  - If we have __ARM_ARCH_ISA_ARM defined, then it's an ARM processor
>    that supports the ARM instruction set (this allows to exclude Thumb-2
>    only processors).
> 
>  - If we have __ARM_ARCH_7A__, then we have an ARMv7-A processor, and
>    we can enable the corresponding optimizations
> 
>  - Same for __aarch64__, __i386__ and __x86_64__.
> 
> In addition, we remove the AC_MSG_ERROR() that makes the build fail for
> all architectures but the ones that are explicitly supported. Indeed,
> webrtc-audio-processing builds just fine for other architectures (tested
> on MIPS), it's just that none of the architecture-specific optimizations
> will be used.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
> ---

Looks good, will push shortly, thanks.

-- Arun