* AST: flatten ControlFlowExpression into Continue, Break, and Return.
* AST: unify identifiers and literals into the same AST type: OneToken
* AST: ControlFlowExpression uses TrailerFlags to optimize storage
space.
* astgen: support `var` as well as `const` locals, and support
explicitly typed locals. Corresponding Module and codegen code is not
implemented yet.
* astgen: support result locations.
* ZIR: add the following instructions (see the corresponding doc
comments for explanations of semantics):
- alloc
- alloc_inferred
- bitcast_result_ptr
- coerce_result_block_ptr
- coerce_result_ptr
- coerce_to_ptr_elem
- ensure_result_used
- ensure_result_non_error
- ret_ptr
- ret_type
- store
- param_type
* the skeleton structure for result locations is set up. It's looking
pretty clean so far.
* add compile error for unused result and compile error for discarding
errors.
* astgen: split builtin calls up to implemented manually, and implement
`@as`, `@bitCast` (and others) with respect to result locations.
* add CLI support for hex and raw object formats. They are not
supported by the self-hosted compiler yet, and emit errors.
* rename `--c` CLI to `-ofmt=[objectformat]` which can be any of the
object formats. Only ELF and C are supported so far. Also added missing
help to the help text.
* Remove hard tabs from C backend test cases. Shame on you Noam, you
are grounded, you should know better, etc. Bad boy.
* Delete C backend code and test case that relied on comptime_int
incorrectly making it all the way to codegen.
I'm allowing incremental compilation of ZIR modules to be broken. This
is not a real use case of ZIR, and the feature requires a lot of code
duplication with incremental compilation of Zig AST (which works great).
The binary file abstraction changed its struct named "Decl" to
"TextBlock" and it now represents an allocated slice of memory in
the .text section. It has two new fields: prev and next, making it
a linked list node. This allows a TextBlock to find its neighbors.
The ElfFile struct now has free_list and last_text_block fields.
Doc comments for free_list are reproduced here:
A list of text blocks that have surplus capacity. This list can have false
positives, as functions grow and shrink over time, only sometimes being added
or removed from the freelist.
A text block has surplus capacity when its overcapacity value is greater than
minimum_text_block_size * alloc_num / alloc_den. That is, when it has so
much extra capacity, that we could fit a small new symbol in it, itself with
ideal_capacity or more.
Ideal capacity is defined by size * alloc_num / alloc_den.
Overcapacity is measured by actual_capacity - ideal_capacity. Note that
overcapacity can be negative. A simple way to have negative overcapacity is to
allocate a fresh text block, which will have ideal capacity, and then grow it
by 1 byte. It will then have -1 overcapacity.
The last_text_block keeps track of the end of the .text section.
Allocation, freeing, and resizing decls are all now more sophisticated,
and participate in the virtual address allocation scheme. There is no
longer the possibility for virtual address collisions.
