Lines from the original source are outputted as comments next to line directives.
Hopefully, this will make debugging codegen problems easier.
Other changes:
The frame setup code now uses a single-line C macro. My motivation was to reduce
the noise in the generated output and make it easier to step over the boiler-plate
code, but counter-intuitively this also improved the overall compilation speed a
little bit so I applied the same treatment to line tracking too (this reduces the size of
the generated files and the explanation is that probably the I/O overhead dominates
the macro expansion costs).
d0edb1826b