QC likely use a lot of Arm IP, Nuvia notwithstanding, and want a way out of the general Arm monopoly. Seems to be a growing trend.
A dual ISA decoder with with fuse-off options will likely have unwelcome power-perf-area and yield consequences.
A dual ISA decoder with with fuse-off options will likely have unwelcome power-perf-area and yield consequences.
Apart from that there’s the other usual angles: The very fact that there’s additional logic in the compute path (eventually fused off) means additional design and verification complexity. The additional area, although dark, eats into the silicon yield at the fab.
Not saying it’s not possible.