This ports the fix from 3d41757788ac. Both LLVM 7 & 8 continue to have this problem.
It fixes rendering issues in some menu and loading screens of Civ VI which can be seen in the trace from bug 104602.
Note: This does not fix the black triangles on Vega for bug 104602.
0e6cdfd561 radeonsi: add a workaround for bitfield_extract when count is 0
src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c | 41 +++++++++++++++++------
1 file changed, 30 insertions(+), 11 deletions(-)