Is there any architecture that uses the same register space for scalar integer and floating point operations?

Question

Most architectures I\'ve seen that support native scalar hardware FP support shove them off into a completely separate register space, separate from the main set of register

Answer 1

The CDC 6600 and Cray 1, both Seymour Cray designs, used a zero exponent to indicate an integer, a kind of tagged architecture. This meant a restricted integer range but a unified floating point / integer register set.

Also, x87 and MMX share registers.