Optimize replication.
Optimize replication.

Since floating-point scalars are stored in vector registers, Subzero
allows us to just bitcast between them, eliminating a load and insert
before shuffling.

Change-Id: Ibccf242fd4cfc28604f35f420a04fd4ee6eabe52
Reviewed-on: https://swiftshader-review.googlesource.com/8575
Tested-by: Nicolas Capens <0612353e1fcebbfd4b302d9337447ca0cdfa9122@google.com>
Reviewed-by: Alexis Hétu <1c7141772178a7e80858c3db5052b328076f08f4@google.com>
Reviewed-by: Nicolas Capens <0612353e1fcebbfd4b302d9337447ca0cdfa9122@google.com>

bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,google/swiftshader,bkaradzic/SwiftShader,google/swiftshader