During parsing, it is possible to see instruction operands that reference
values or EBBs that have not been created yet. These references have to be
resolved by a second pass following parsing once all EBBs and values have been
created.
To prepare for this second pass, start creating Ebb and Value references that
use the numbering from the source file rather than the in-memory real
references. Maintain Value -> Value and Ebb -> Ebb mappings. This makes it
possible to store source-numbered Ebb and Value references in instructions.
All other entities are created in the preamble, so they should have been created
before they are referenced.
Create map entries for ebbs and values as they are defined, but leave ebb and
value operands unresolved on instructions as they are parsed. Instruction
operands can refer to ebbs and values that may not have been defined yet.
Don't infer or check result types yet.
libctonfile -> libreader.
This library will only provide .cton file reading/parsing services which are
not needed after deployment.
Code for writing .cton files lives in the main cretonne library because it is
fairly small, and because it is useful for extracting test cases from a
deployed library.
