Originally reverted because of a bug in Range that is now fixed
(#86041), we can reland this commit. Tests have been added to ensure the
miscompile that caused the revert does not happen again.
We were passing the min and max values of the range to the ConstantRange
constructor, but the constructor expects the upper bound to 1 more than
the max value so we need to add 1.
We also need to use getNonEmpty so that passing 0, 0 to the constructor
creates a full range rather than an empty range. And passing smin,
smax+1 doesn't cause an assertion.
I believe this fixes at least some of the reason #79158 was reverted.
The range for these operations is being constructed without the
maximum value for the range due to an incorrect usage of the
ConstantRange constructor.
This causes Float2Int to think the range for 'uitofp i1' only
contains 0 instead of 0 and 1.
