xlc 16.1 can't interpret asm lines in Eigen TPL
Issue found while debugging #20454 (closed). The workaround for that issue is needed, or you will run into those errors first. Once that is fixed the xlc build now fails with:
In file included from /home/stam/projects/paraview/src/VTK/Filters/Statistics/vtkPCAStatistics.cxx:19: In file included from /home/stam/projects/paraview/src/VTK/ThirdParty/eigen/vtkeigen/eigen/Dense:1: In file included from /home/stam/projects/paraview/src/VTK/ThirdParty/eigen/vtkeigen/eigen/Core:399: /home/stam/projects/paraview/src/VTK/ThirdParty/eigen/vtkeigen/eigen/src/Core/arch/AltiVec/PacketMath.h:941:71: error: 1540-0557 The asm operand does not match the specified constraint. __asm__ ("xvcmpgtdp %x0,%x2,%x1\n\txxsel %x0,%x1,%x2,%x0" : "=&wa" (ret) : "wa" (a), "wa" (b)); ^ 1 error generated. Error while processing /home/stam/projects/paraview/src/VTK/Filters/Statistics/vtkPCAStatistics.cxx.
Eigen devs are aware of the issue: https://gitlab.com/libeigen/eigen/-/issues/1555#note_435626297