Bug#1057050: qt6-multimedia: Please build with EIGEN_DONT_VECTORIZE on powerpc to fix FTBFS

[John Paul Adrian Glaubitz]

Source: qt6-multimedia
Version: 6.4.2-11
Severity: normal
User: debian-...@lists.debian.org
Usertags: powerpc
X-Debbugs-Cc: debian-...@lists.debian.org

Hello!

The package src:qt6-multimedia fails to build from source on powerpc since version
6.4.0-1 due to the use of some AltiVec instrisics that are not supported on 32-bit
PowerPC:

/usr/bin/c++ -DEIGEN_MPL2_ONLY -DQT_NO_DEBUG -DQT_NO_EXCEPTIONS -DQT_NO_JAVA_STYLE_ITERATORS \
(...)
In file included from /usr/include/eigen3/Eigen/Core:210,
from /usr/include/eigen3/Eigen/Dense:1,
from /<<PKGBUILDDIR>>/src/resonance-audio/../3rdparty/resonance-audio/platforms/common/utils.h:20,
from /<<PKGBUILDDIR>>/src/3rdparty/resonance-audio/platforms/common/utils.cc:17:
/usr/include/eigen3/Eigen/src/Core/arch/AltiVec/PacketMath.h: In function \
‘Packet Eigen::internal::pblend(const Selector<unpacket_traits<T>::size>&, const Packet&, const Packet&) [with Packet = __vector(2) double]’:
/usr/include/eigen3/Eigen/src/Core/arch/AltiVec/PacketMath.h:2702:17: error: invalid parameter combination for AltiVec intrinsic ‘__builtin_vec_sel’
2702 | return vec_sel(elsePacket, thenPacket, mask);
| ^

This can be fixed by switching off vectorization in the »eigen« using the preprocessor
macro EIGEN_DONT_VECTORIZE which can be defined on the cmake command line using the
cmake variable COMPILE_DEFINITIONS:

--- qt6-multimedia-6.4.2/debian/rules.orig 2023-07-26 17:52:13.000000000 +0200
+++ qt6-multimedia-6.4.2/debian/rules 2023-11-28 18:26:47.950137854 +0100
@@ -9,6 +9,10 @@
cmake_extra_args += -DQT_HOST_PATH=/usr
endif

+ifneq (,$(filter $(DEB_HOST_ARCH),powerpc))
+ cmake_extra_args += -DCOMPILE_DEFINITIONS="EIGEN_DONT_VECTORIZE"
+endif
+
%:
dh $@ --with pkgkde_symbolshelper --buildsystem=cmake+ninja

With the above change, cmake defines the preprocessor macro EIGEN_DONT_VECTORIZE and
the build succeeds on powerpc.

Could you apply this change for the next upload in order to fix the build on powerpc?

Attaching a patch for a convenience.

Thanks,
Adrian

--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer
`. `' Physicist
`- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913

[Christian Marillat]

On 02 déc. 2023 00:46, Patrick Franz <delt...@debian.org> wrote:

> Hej,
>
> Am Dienstag, 28. November 2023, 20:22:36 CET schrieb John Paul Adrian
> Glaubitz:
> [...]

>> With the above change, cmake defines the preprocessor macro
>> EIGEN_DONT_VECTORIZE and the build succeeds on powerpc.
>>
>> Could you apply this change for the next upload in order to fix the
>> build on powerpc?
>

> We're in the middle of packaging Qt 6.6 and I had not planned to do any
> more 6.4.2 updates unless absolutely necessary.
>
> Do you know whether this patch will also work on Qt 6.6.1 ?

Of course yes :

,----
| $ rgrep EIGEN_DONT_VECTORIZE qtmultimedia-everywhere-src-6.6.1/
| qtmultimedia-everywhere-src-6.6.1/src/3rdparty/eigen/Eigen/src/Core/util/ConfigureVectorization.h:#if defined(EIGEN_DONT_VECTORIZE)
| qtmultimedia-everywhere-src-6.6.1/src/3rdparty/eigen/Eigen/src/Core/util/ConfigureVectorization.h: #ifndef EIGEN_DONT_VECTORIZE
| qtmultimedia-everywhere-src-6.6.1/src/3rdparty/eigen/Eigen/src/Core/util/ConfigureVectorization.h: #define EIGEN_DONT_VECTORIZE
| qtmultimedia-everywhere-src-6.6.1/src/3rdparty/eigen/Eigen/src/Core/util/ConfigureVectorization.h:#if !(defined(EIGEN_DONT_VECTORIZE) || defined(EIGEN_GPUCC))
| qtmultimedia-everywhere-src-6.6.1/src/3rdparty/eigen/Eigen/src/Core/util/Macros.h: #ifndef EIGEN_DONT_VECTORIZE
| qtmultimedia-everywhere-src-6.6.1/src/3rdparty/eigen/Eigen/src/Core/util/Macros.h: #define EIGEN_DONT_VECTORIZE
| qtmultimedia-everywhere-src-6.6.1/src/3rdparty/eigen/Eigen/src/Core/arch/SYCL/InteropHeaders.h:#if !defined(EIGEN_DONT_VECTORIZE_SYCL)
| qtmultimedia-everywhere-src-6.6.1/src/3rdparty/eigen/Eigen/Core:#if !defined(EIGEN_DONT_VECTORIZE_SYCL)
`----

Christian

[Christian Marillat]

On 02 déc. 2023 10:10, John Paul Adrian Glaubitz <glau...@physik.fu-berlin.de> wrote:

> Hi!

>
> On Sat, 2023-12-02 at 00:46 +0100, Patrick Franz wrote:
>> We're in the middle of packaging Qt 6.6 and I had not planned to do any
>> more 6.4.2 updates unless absolutely necessary.
>>
>> Do you know whether this patch will also work on Qt 6.6.1 ?
>

> Yes, absolutely. And since it only adds some powerpc-specific lines to
> debian/rules, there is nothing really that would need to be rebased
> when updating to a newer Qt version.
>
> It's always safe to apply this patch.

It is possible to see this bug fixed ?

Christian

[Christian Marillat]

On 07 déc. 2023 08:16, John Paul Adrian Glaubitz <glau...@physik.fu-berlin.de> wrote:

> Hi Christian!

Hi Adrian,

> On Thu, 2023-12-07 at 08:09 +0100, Christian Marillat wrote:
>> > It's always safe to apply this patch.
>>
>> It is possible to see this bug fixed ?
>

> I have uploaded a patched version to unreleased for the time being.

Thanks I didn't noticed.

> However, fixing this should be a no-brainer and wouldn't affect anything else.

...

Christian

[Patrick Franz]

Hej,

Am Donnerstag, 7. Dezember 2023, 08:09:50 CET schrieb Christian
Marillat:

I'll include the fix in 6.6.1 which is being worked on.


--
Med vänliga hälsningar

Patrick Franz