It seems many of the initial arch/uarch states, including the GPR, are
uninitialized in the VCS simulation, which results in functional errors caused
by propagated X's. In this particular case it resulted in a dcache request not
being fired due to the rs1 data for an lw instruction having values as X,
causing the smem_unit to not arbitrate the request correctly.
A workaround of this issue is to stop the X propagation by using the
===-operation instead of == in the GPR unit, which had been the main source of X
propagation into the raddr port of the GPR.
Also, we run the simulation with GSR_RESET set to 1 so that the contents of the
GPR are initialized at the beginning of the simulation (however, this alone does
not prevent reading in X's, hence this fix.)
FIXME: This is a slight deviation from the upstream code; ideally, we want to do
clean & full initialization of microarchitectural states.
90e21e8e58