The implementation for add_with_overflow and sub_with_overflow is now a lot
more robust and takes account for signed integers and arbitrary integer bitsizes.
The final output is equal to that of the LLVM backend.
Most of the work here was additions to zig.h. The lowering code is
mainly responsible for calling the correct function name depending on
the operand type.
Some of the compiler-rt calls here are not implemented yet and are
non-standard symbols due to the C programming language not needing them.
After this commit, the behavior tests with -ofmt=c are passing again.
Originally I thought interleaving AIR with MIR will be useful, however
as it stands, I have used it very sporadically, and recently, not at
all, and I do not think anyone else is actually using it. If there is
a simple error such as a wrong instruction emitted,
`objdump` is perfectly capable of narrowing it down, while if there's
something more subtle happening, regardless of having `--verbose-mir`
functionality or not, you still gotta go via the debugger which
offers a better view at interleaved source program with the emitted
machine code. Finally, I believe `-femit-asm` when we add it will offer a
more generic substitute.
While calling `next` an error can occur while parsing the file.
However, we don't set the filename that is currently being processed, until `next` completed successfully.
This means that for invalid test names, the wrong filename was being displayed in the panic message.
The fix is to retrieve the correct filename when an error occurs and then setting the filename appropriately.
This matches master branch. We can look into adding more target coverage
as we switch to stage2. As it stands, this works around having to
duplicate the "Executor" logic to figure out when to not run the tests
due to them being non-native.
