This PR enables all incremental tests under the `test/incremental` directory, except one: `change_exports`, which is currently ignored as it requires a non-trivial amount of work on the linker, since we do not currently support exporting data symbols.
To enable the other tests, the following fixes were needed:
1. `src/link/Wasm.zig`: instead of chasing function type through Nav, get it directly.
2. `src/target.zig`: `.panic_fn` appears to work fine with the wasm backend.
3. `src/codegen/wasm/CodeGen.zig`: there was a liveness related bug that caused some `ArenaAllocator` code to crash the backend.
More info on (3), the liveness and local reuse code in the backend for years in unfinished state. For example there is currently no branch merging and reuse happens only when inst die in same block level. I initially considered doing a large refactor to implement everything correctly, but aborted due to its sheer size and currently! no clear idea about how to do this efficiently.
Instead, I fixed the bug with minimal changes and removed useless code, keeping the old solution otherwise intact.
These all pass now! I have also removed the warning about the LLVM
backend not supporting incremental compilation; I expect it will work
sort of okay in practice by now.
On Windows, it is sometimes problematic to depend on ws2_32.dll. Before,
users of std.Io.Threaded would have to call ioBasic() rather than io()
in order to avoid unnecessary dependencies on ws2_32.dll. Now, the
application can disable networking with std.Options.
This change is necessary due to moving networking functionality to
be based on Io.Operation, which is a tagged union.
These cases have been disabled for a while, and we have transitioned to
using a compact file format for incremental test cases.
I was originally planning to port all of these cases, but the vast
majority aren't testing anything interesting, so it wasn't worth the
effort. I did look through each one; anything interesting being tested
has been extracted into a new case in `test/incremental/`.
Two of the new tests are currently failing with the self-hosted ELF
linker, and thus are currently only enabled with the C backend.
Resolves: #12844
Alex Rønne Petersen