How could it exist on other arches?  The header is for x86 intrinsics.
The fact that ppc64le decided to emulate (very small portion of) it doesn't mean it can or should be emulated on other architectures.
Other architectures have their own intrinsics with their own headers, or you can use e.g. generic vector support in the compiler.

Sorry there was some confusion on IRC and I didn't intend the xmmintrin.h issue to be reported here.

There are actually two separate issues - the code is non portable in that it requires xmmintrin.h which causes the build to fail on aarch64. That is not a gcc issue.

The second is an ICE on ppc64le which is a gcc and is what this bug was intended to report. The log for that is https://kojipkgs.fedoraproject.org//work/tasks/9768/58189768/build.log and the actual error is:

/builddir/build/BUILD/darktable-3.4.0/src/iop/denoiseprofile.c:3140:17: note: the layout of aggregates containing vectors with 8-byte alignment has changed in GCC 5
 3140 | static gboolean denoiseprofile_draw(GtkWidget *widget, cairo_t *crf, gpointer user_data)
      |                 ^~~~~~~~~~~~~~~~~~~
/builddir/build/BUILD/darktable-3.4.0/src/iop/channelmixerrgb.c: In function 'process':
/builddir/build/BUILD/darktable-3.4.0/src/iop/channelmixerrgb.c:1114:1: error: unrecognizable insn:
 1114 | }
      | ^
(insn 356 355 357 19 (set (reg:DI 366)
        (unlt:DI (reg:CCFP 365)
            (const_int 0 [0]))) "/builddir/build/BUILD/darktable-3.4.0/src/common/illuminants.h":405:8 -1
     (nil))
*** WARNING *** there are active plugins, do not report this as a bug unless you can reproduce it without enabling any plugins.
Event                            | Plugins
PLUGIN_FINISH_UNIT               | annobin: Generate final annotations
PLUGIN_START_UNIT                | annobin: Generate global annotations
PLUGIN_ALL_PASSES_START          | annobin: Generate per-function annotations
PLUGIN_ALL_PASSES_END            | annobin: Register per-function end symbols
during RTL pass: vregs
/builddir/build/BUILD/darktable-3.4.0/src/iop/channelmixerrgb.c:1114:1: internal compiler error: in extract_insn, at recog.c:2294
[ 67%] Linking C shared module libfilmicrgb.so
cd /builddir/build/BUILD/darktable-3.4.0/ppc64le-redhat-linux-gnu/lib64/darktable/plugins && /usr/bin/cmake -E cmake_link_script CMakeFiles/filmicrgb.dir/link.txt --verbose=1
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://bugzilla.redhat.com/bugzilla> for instructions.
make[3]: *** [/tmp/cc7sePFd.mk:2: /tmp/libchannelmixerrgb.so.yVpgPf.ltrans0.ltrans.o] Error 1

Yes I am sorry I made a mistake switching two different bugs we were speaking about in #fedora-devel , about ppc and aarch64 darktable 3.4.0 build failures.

(bugzilla mid air collision :-( )

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If I can tell, then it has been already fixed in some of the 11.2.1 updates. gcc-11.2.1-1.fc34 from F-34 updates still has the problem, but gcc-11.2.1-7.fc36 in Rawhide has not.