Previous to this patch we only materialized 0.0 and all other floating point
values would be loaded from the TOC. This patch adds materialization for the
floating point values that can be represented as integers in [-16.0, 15.0].
For example we will now materialize 3.0 and -5.0 but not 4.7.
Previous behavour is "fallthrough" which will result in a return of Imm.isPosZero(). Do we not want the defalut to be same as before?