* 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.
Otherwise, the behaviour can lead to unexpected results, resulting
in removing an entire tree that's not necessarily under the root.
Furthermore, this change is needed if are to properly handle dir
symlinks on Windows. Without explicitly requiring that a directory
or file is opened with `FILE_OPEN_REPARSE_POINT`, Windows automatically
dereferences all symlinks along the way. This commit adds another
option to `OpenDirOptions`, namely `.no_follow`, which defaults to
`false` and can be used to specifically open a directory symlink on
Windows or call `openat` with `O_NOFOLLOW` flag in POSIX.
This way `std.fs.symlinkAbsolute` becomes cross-platform and we can
legally include `SymlinkFlags` as an argument that's only used on
Windows. Also, now `std.os.symlink` generates a compile error on
Windows with a message to instead use `std.os.windows.CreateSymbolicLink`.
Finally, this PR also reshuffles the tests between `std.os.test` and
`std.fs.test`.
InfixOp is flattened out so that each operator is an independent AST
node tag. The two kinds of structs are now Catch and SimpleInfixOp.
Beginning implementation of supporting codegen for const locals.
ast.Node.Id => ast.Node.Tag, matching recent style conventions.
Now multiple different AST node tags can map to the same AST node data
structures. In this commit, simple prefix operators now all map top
SimplePrefixOp.
`ast.Node.castTag` is now preferred over `ast.Node.cast`.
Upcoming: InfixOp flattened out.
These AST nodes now have a flags field and then a bunch of optional
trailing objects. The end result is lower memory usage and consequently
better performance. This is part of an ongoing effort to reduce the
amount of memory parsed ASTs take up.
Running `zig fmt` on the std lib:
* cache-misses: 2,554,321 => 2,534,745
* instructions: 3,293,220,119 => 3,302,479,874
* peak memory: 74.0 MiB => 73.0 MiB
Holding the entire std lib AST in memory at the same time:
93.9 MiB => 88.5 MiB
This is useful for saving memory when allocating an object that has many
optional components. The optional objects are allocated sequentially in
memory, and a single integer is used to represent each optional object
and whether it is present based on each corresponding bit.
This is part of a larger effort to improve the memory layout of AST
nodes of the self-hosted parser to reduce wasted memory. Reduction of
wasted memory also translates to improved performance because of fewer
memory allocations, and fewer cache misses.
Compared to master, when running `zig fmt` on the std lib:
* cache-misses: 801,829 => 768,624
* instructions: 3,234,877,167 => 3,232,075,022
* peak memory: 81480 KB => 75964 KB
