OpName is only for debug information, so we must be very careful that
we do not reuse the same name for different variables.
This was previously done for local variables, but this commit extends
this to global variables as well.
In some cases we need to bitcast when dealing with int vs. uint.
SPIR-V allows inputs to be of different integer signedness, so we need
to deal with this somehow.
Add testing system to test SPIR-V assembly.
For now, test all possible combination for all major cases.
- IAdd (which doesn't care about input type as long as they're equal)
- SDiv/UDiv operations which case about input type.
- Arith/Logical right shifts.
- IEqual to test outputs to bvec, which shouldn't get output cast. Also
tests casting in function-like calls.
