`EscapeInfo` now conforms to the generic protocols defined in `WalkUtils`.
This simplifies the implementation a bit, since trivial instructions are handled
by `WalkUtils` and `EscapeInfo` only has to handle a subset of instructions
inherent to escape information.
Passes using `EscapeInfo` are updated accordingly to become visitors that
customize the `EscapeInfo` walk.
Add a flag `analyzeAddresses` for distinguishing address vs value escape analysis. This is simpler than handling that in the visitUse/visitDef closures.
Also, fix a related bug, which let an address, which is escaping to a function, get unnoticed.
It’s a replacement for the old `EscapeAnalysis`, implemented in Swift (instead of C++) and with a much simple design and implementation.
While the old EscapeAnalysis builds a connection graph, the new EscapeInfo just performs a simple def-use and use-def walk in the SIL.
The EscapeInfo does not need to analyze the whole function (like the EscapeAnalysis does), but just the relevant value which is inspected. Therefore EscapeInfo is not an `Analysis` which caches its result across optimization passes - it’s not needed.
It’s a replacement for the old `EscapeAnalysis`, implemented in Swift (instead of C++) and with a much simple design and implementation.
While the old EscapeAnalysis builds a connection graph, the new EscapeInfo just performs a simple def-use and use-def walk in the SIL.
The EscapeInfo does not need to analyze the whole function (like the EscapeAnalysis does), but just the relevant value which is inspected. Therefore EscapeInfo is not an `Analysis` which caches its result across optimization passes - it’s not needed.
