Replace the make_multi_inst() function with a make_inst_results() which uses
the constraint system to create the result values. A typevar argument ensures
that this function does not infer anything from the instruction data arguments.
These arguments may not be valid during parsing.
Implement basic type inference in the parser. If the designated value operand
on a polymorphic instruction refers to a known value, use that to infer the
controlling type variable.
This simple method of type inference requires the operand value to be defined
above the use in the text. Since reordering the EBBs could place a dominating
EBB below the current one, this is a bit fragile. One possibility would be to
require the value is defined in the same EBB. In all other cases, the
controlling typevar should be explicit.
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.
This will eventualy be used for add-with-carry and add-with-overflow type
instructions. For now it only serves as a representative of instruction formats
that have multiple_results=True and boxed_storage=False at the same time.
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.
Avoid gathering too much code in repr.rs.
The `entities` module contains entity reference types, and the `instructions`
module contains instruction opcodes and formats.
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.
