[FIX] Cast pre-loaded values correctly or reload them with adjusted type.

Especially for structs, the SAI object of a base pointer does not
describe all the types that the user might expect when he loads from
that base pointer. While we will still cast integers and pointers we
will now reload the value with the correct type if floating point and
non-floating point values are involved. However, there are now TODOs
where we use bitcasts instead of a proper conversion or reloading.

This fixes bug 25479.

llvm-svn: 252706