[Debichem-devel] Bug#983942: gromacs: ftbfs with -march=x86-64-v3

[Graham Inggs]

Hi Nicholas

I made the changes below to debian/rules in Ubuntu.  I'm not sure if
it makes sense to apply them in Debian (yet), but here they are for
reference.

 export DEB_BUILD_MAINT_OPTIONS = hardening=+all
+export DEB_CFLAGS_MAINT_STRIP = -march=x86-64-v3
+export DEB_CXXFLAGS_MAINT_STRIP = -march=x86-64-v3
+export DEB_LDFLAGS_MAINT_STRIP = -march=x86-64-v3

I think it is fine to do this unconditionally, we don't want
-march=x86-64-v3 on any architecture.

> If there's a future way to detect an x86-64-v3 build, I think the
> sensible fix here is to raise the baseline SIMD choice to match.

In Ubuntu's amd64v3 implementation, DEB_HOST_ARCH remains amd64, and
DEB_HOST_ARCH_VARIANT is set to  amd64v3.

 ifeq (,$(findstring cpuopt,$(DEB_BUILD_OPTIONS)))
 ifeq ($(DEB_HOST_ARCH), amd64)
+ifeq ($(DEB_HOST_ARCH_VARIANT), amd64v3)
+ COMMON_CONFIG_PARAMS += -DGMX_SIMD=AVX2_256
+else
  COMMON_CONFIG_PARAMS += -DGMX_SIMD=SSE4.1
+endif
 else ifeq ($(DEB_HOST_ARCH), arm64)
  COMMON_CONFIG_PARAMS += -DGMX_SIMD=ARM_NEON_ASIMD
 else

I set GMX_SIMD=AVX2_256 based on the suggestion in LP: #2131605 [1].

Regards
Graham


[1] https://bugs.launchpad.net/ubuntu/+source/gromacs/+bug/2131605