[Speex-dev] Compilation failure in resample_neon.h on aarch64

Tristan Matthews tmatth at videolan.org
Tue Jul 7 08:19:31 PDT 2015

On Tue, Jul 7, 2015 at 10:43 AM, Tanu Kaskinen <tanuk at iki.fi> wrote:
> On Tue, 2015-07-07 at 18:40 +0930, Ron wrote:
>> On Mon, Jul 06, 2015 at 05:35:51PM +0300, Tanu Kaskinen wrote:
>> > Hi all,
>> >
>> > I'm updating OpenEmbedded-core's speexdsp from 1.2rc1 (when it still was
>> > a part of the speex source tree) to 1.2rc3. I found out that building
>> > the new version for aarch64 fails in resample_neon.h (the target machine
>> > is OE-core's default qemuarm64 target). This is the error message:
>> >
>> > .../speexdsp-1.2rc3/libspeexdsp/resample_neon.h:148:5: error: impossible constraint in 'asm'
>> >      asm volatile ("  cmp %[len], #0\n"
>> >      ^
>> >
>> > I haven't dealt with assembly code enough to be able to decipher the
>> > error message. Does anyone have ideas how to fix this, or have further
>> > debugging advice? For the time being I'll resort to using --disable-neon
>> > when building for aarch64, that allows the build to succeed.
>> >
>> > I don't know for sure that this is aarch64 specific, because it seems
>> > that OE-core's 32-bit qemuarm target doesn't have NEON support
>> > available, so I haven't tested building for NEON-enabled 32-bit ARM.
>> >
>> > (Jyri, in case you wonder, I put you in CC since you're the author of
>> > the failing code. The commit is from 2011, though, so you might not
>> > remember anything about it :)
>> It's possibly complaining about the 'l' constraints, which might not be
>> valid for aarch64.  I think pretty much all of the ARM asm we have here
>> needs to be reworked for aarch64 still.  We had to disable it for the
>> Debian port to that platform, and there were a few promises by people
>> to look at fixing that but I'm not aware of any patches emerging yet.
> Thanks for the tip about the "l" constraints. I'll join the crowd of
> people who will maybe some day look deeper into this.

VLC was also bit by this:


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