suggested alternatives:
- actual tests
- explicitly list the decls
- compile an example application that uses the API
- stop worrying about dead code
- refAllDecls (non recursive) in each file
Don't fight the laziness, embrace it.
closes#23608closes#30813
- remove file_size parameter from MemoryMap.write
- remove requirement for mapping length to be aligned
- align allocated fallback memory
- add unit test for std.Io.Threaded.disable_memory_mapping = true
- add unit test for MemoryMap.setLength
- change offset to u64
- make len non-optional
- make write take a file_size parameter
- std.Io.Threaded: introduce disable_memory_mapping flag to force it to
take the fallback path.
Additionally:
- introduce BlockSize to File.Stat. On Windows, based on cached call to
NtQuerySystemInformation. On unsupported OS's, set to 1.
- support File.NLink on Windows. this was available the whole time, we
just didn't see the field at first.
- remove EBADF / INVALID_HANDLE from reading/writing file error sets
by defining the pointer contents to only be synchronized after explicit
sync points, makes it legal to have a fallback implementation based on
file operations while still supporting a handful of use cases for memory
mapping.
furthermore, it makes it legal for evented I/O implementations to use
evented file I/O for the sync points rather than memory mapping.
not yet done:
- implement checking the length when options.len is null
- some windows impl work
- some wasi impl work
- unit tests
- integration with compiler
On NetBSD and Illumos, we were using the `std.Thread.Futex`-based
implementation of `std.Thread.Mutex`. But since futex is not a primitive
on these targets, the implementation of `std.Thread.Futex` was based on
pthread primitives, including `pthread_mutex_t`. This had the amusing
consequence that locking a contended mutex on NetBSD would actually
perform 2 mutex locks, 2 mutex unlocks, and 1 condition wait; likewise,
unlocking a contended mutex would perform 2 mutex locks, 2 mutex
unlocks, and 1 condition signal. Having read some cutting-edge studies,
I have concluded that this is a slightly suboptimal approach. Instead,
let's just use pthread mutexes directly in this case; that's an
obviously better idea.
In the future, I think we can probably entirely remove our usages of
pthread sync primitives---no platform actually treats them as the base
primitives. Of the platforms which std has any meaningful support for
today, most support futexes, and the exceptions (NetBSD and Illumos)
support a thread parking API. We can implement futex and/or mutex on top
of thread parking and drop the pthread dependency entirely.
Apparently the thread parking APIs on Windows and NetBSD aren't as good
as I thought---or, at least, the way they're *used* makes them not as
good. It's perfectly possible to use these APIs in a way where you don't
trigger spurious wakeups, but standard primitives (SRWLOCK on Windows,
pthread bits on NetBSD) are perfectly happy to leave pending unparks
sitting around, meaning in practice you have to assume spurious unparks
are possible. This brings me great sadness... but we soldier on!
When targeting x86-windows, this parameter referring to read-only memory can result in an ACCESS_VIOLATION error, and this has been seen when using FILE_DISPOSITION_INFORMATION_EX. It's unclear how exactly this ACCESS_VIOLATION is occurring, though, as the memory does not actually change before/after the call.
Closes https://codeberg.org/ziglang/zig/issues/30802
This allows stack overflows to print stack traces. The size of the
sigaltstack (and whether it is actually set) can be configured by
setting `std.Options.signal_stack_size`.
The default value for the signal stack size was chosen experimentally by
doubling the value required to get stack traces on stack overflow with
the self-hosted x86_64 backend. While some targets may typically use
more stack space than x86_64-linux, the self-hosted x86_64 backend is
quite wasteful with stack at the moment, making it a fair benchmark.
Executables produced by the LLVM backend should have lower stack usage.
Commit dec1163fbb removed sentinels from the returned slice for C
pointers. Since C pointers have no bounds, we know that it'll keep
scanning until it finds `end` (or crash trying). The same is also true
of many-item pointers without a sentinel (e.g. `[*]T`), so I added
support for those too.
e2338edb47 didn't *quite* do it, the call sites of all switch prong related
functions now have to do their part too and be a little more precise about
what kind of prong they're currently analyzing.
Also removes some unused/unnecessary stuff.
- Corrects WASI `UTIME_*` definitions now that the libc build has been
fixed (see previous commit), and adds the corresponding definitions
for Emscripten which were missing.
- Fixes `dirReadUnimplemented()`, which didn't compile.
- Prevents a dependency on `pthread_kill` from being pulled in in
single-threaded Emscripten builds, where it isn't defined.
With these changes, Emscripten can now participate in juicy main.
This fixes a regression from a couple of commits ago; breaking from the
`else` block of a loop to the loop's tag should be allowed when explicitly
targeting the label by name.
When switching on an error, using the captured value instead of the original
one is always preferable since its error set has been narrowed to only
contain errors which haven't already been handled by other switch prongs.
The subsequent commits will disallow this form as an unreachable `else` prong.
Moved to a more linear layout which lends itself well to exposing an iterator.
Consumers of this iterator now just have to keep track of an index into a
homogenous sequence of bodies.
The new ZIR layout also enables giving switch prong items result locations
by storing the bodies of all items inside of the switch encoding itself.
There are some deliberate exceptions to this: enum literals and error values
are directly encoded as strings and number literals are resolved to comptime
values outside of the switch block. These special encodings exist to save
space and can easily be resolved during semantic analysis.
This commit also re-implements `AstGen` and `print_zir` for switch based on
the new layout and adds some additional information to the ZIR text repr.
Notably `switchExprErrUnion` has been merged into `switchExpr` to reduce
code duplication.
The rules around allowing an unreachable `else` prong in error switches are
also refined by this commit, and enforced properly based on the actual AST.
The special cases are listed exhaustively below:
`else => unreachable,`
`else => return,`
`else => |e| return e,` (where `e` is any identifier)
Additionally `{...} => comptime unreachable,` prongs are marked to support
future features (refer to next couple of commits).
Also fixes 'value with comptime-only type depends on runtime control flow'
error for labeled error switch statements by surrounding the entire expr
with a common block to break to (see previous commits for details).
Adds `Scope.Unwrapped`, a simple union of pointers to already-casted scopes
with `Scope.Tag` as its tag enum. This pairs very nicely with labeled switch
and gets rid of almost every `scope.cast(...).?`, improving developer QOL :)
Enhances `GenZir` to allow labels to provide separate `break` and `continue`
target blocks and adds some more information on continue targets to
communicate whether the target is a switch block or cannot be targeted by
`continue` at all.
The main motivation is enabling this:
```
const result: u32 = operand catch |err| label: switch (err) {
else => continue :label error.MyError,
error.MyError => break :label 1,
};
```
to be lowered to something like this:
```
%1 = block({
%2 = is_non_err(%operand)
%3 = condbr(%2, {
%4 = err_union_payload_unsafe(%operand)
%5 = break(%1, result) // targets enclosing `block`
}, {
%6 = err_union_code(%operand)
%7 = switch_block(%6,
else => {
%8 = switch_continue(%7, "error.MyError") // targets `switch_block`
},
"error.MyError" => {
%9 = break(%1, @one) // targets enclosing `block`
},
)
%10 = break(%1, @void_value)
})
})
```
which makes the non-error case and all breaks from switch prongs, but not
continues from switch prongs, peers.
This is required to avoid the problems described in gh#11957 for labeled
switches without having to introduce a fairly complex special case to the
`switch_block_err_union` logic. Since this construct is very rare in practice,
introducing this additional complexity just to save a few ZIR bytes is
likely not worth it, so the simplified lowering described above will be
used instead.
As a nice bonus, AstGen can now also detect a `continue` trying to target
a labeled block and emit an appropriate error message.
Previously Zig allowed you to write something like,
```zig
switch (x) {
.y => |_| {
```
This seems a bit strange because in other cases, such as when
capturing the tag in a switch case,
```zig
switch (x) {
.y => |_, _| {
```
this produces an error.
The only usecase I can think of for the previous behaviour is
if you wanted to assert that all union payloads are able
to coerce,
```zig
const X = union(enum) { y: u8, z: f32 };
switch (x) {
.y, .z => |_| {
```
This will compile-error with the `|_|` and pass without it.
I don't believe this usecase is strong enough to keep the current
behaviour; it was never used in the Zig codebase and I cannot
find a single usage of this behaviour in the real world, searching
through Sourcegraph.
Since we ignore this flag in `clang_options_data.zig`, it makes
sense to ignore it for Nix as well. One thing I've been thinking about
is if it would make sense to somehow use `clang_options_data.zig` as
source of truth for handling Nix cflags too rather than slap more
hard-coded escape hatches.
murtaza