Manual comments that are easier to use.

[rakudrama]

Placeholder comment

It might be easier to handle source-maps if the number of lines in the code does not change.
Some compilers (e.g. dart2js) have source-map extensions that are not handled will by third-party tooling.

One way to support this is to have a comment that specifies nothing
Is this supported by having no data?

//# functionsCalledOnLoad=

Supporting experimentation

While the binary data format will be comprehensive and compact, it is cumbersome for developers to experiment with, requiring tooling to support a POGO round-trip.

Could we also add a version that tags functions on the next line?

//# functionsCalledOnLoad=next-line
X.foo = function() {...}

The compilation hint applies to any function whose first token is on the following line.

If a team has a manual-only process, tooling might support smaller downloads by rolling multiple comments like this up to a prior binary data format comment,

[marjakh]

In a typical use case, there would be thousands of functions marked for eager compilation, and that's why we haven't considered supporting any manual workflows. We have good performance measurements results with the PGO but with manually marking some functions, the performance results would be much weaker, probably not measurable at all.