In cf88cf2657d721c68055a284e8c498a18639f74c the eql function provided in
The context of ArrayHashMap was changed to also include the key index,
but this wasn't properly updated in the documentation.
Since a flat `usize` is unintuitive, I've tried to explain the function
of the parameter as best I can based on the original commit.
Finally, I didn't do an extensive search if this eql definition is
incorrectly stated anywhere outside of these 2 spots. But I somewhat
doubt an file outside of `array_hash_map` would
The previous commit cast doubt upon the initial report about macOS
kernel behavior, identifying another reason that ENOENT could be
returned from file creation.
However, it is demonstrable that ENOENT can be returned for both cases:
1. create file race
2. handle refers to deleted directory
This commit re-introduces the workaround for the file creation race on
macOS however it does not unconditionally retry - it first tries again
with O_EXCL to disambiguate the error condition that has occurred.
Previous commits
2b0929929d67e222ca6a9523a3a594ed456c4a51
4ea2f441df36cec61e1017f4d795d4037326c98c
had this text:
> There are no dir components, so you would think that this was
> unreachable, however we have observed on macOS two processes racing to
> do openat() with O_CREAT manifest in ENOENT.
This appears to have been a misunderstanding based on the issue
report #12138 and corresponding PR #12139 in which the steps to
reproduce removed the cache directory in a loop which also executed
detached Zig compiler processes.
There is no evidence for the macOS kernel bug however the ENOENT is
easily explained by the removal of the cache directory.
This commit reverts those commits, ultimately reporting the ENOENT as an
error rather than repeating the create file operation. However this
commit also adds an explicit error set to `std.Build.Cache.hit` as well
as changing the `failed_file_index` to a proper diagnostic field that
fully communicates what failed, leading to more informative error
messages on failure to check the cache.
The equivalent failure when occuring for AstGen performs a fatal process
kill, reasoning being that the compiler has an invariant of the cache
directory not being yanked out from underneath it while executing. This
could be made a more granular error in the future but I suspect such
thing is not valuable to pursue.
Related to #18340 but does not solve it.
Whatever was in the frame pointer register prior to clone() will no longer be
valid in the child process, so zero it to protect FP-based unwinders. This is
just an extension of what was already done for i386 and x86_64. Only applied
to architectures where the _start() code also zeroes the frame pointer.
Whatever was in the frame pointer register prior to clone() will no longer be
valid in the child process, so zero it to protect FP-based unwinders. Similarly,
mark the link register as undefined to protect DWARF-based unwinders.
This is only zeroing the frame pointer(s) on Arm/Thumb because of an LLVM
assembler bug: https://github.com/llvm/llvm-project/issues/115891
The goal here is to support both levels of unwind tables (sync and async) in
zig cc and zig build. Previously, the LLVM backend always used async tables
while zig cc was partially influenced by whatever was Clang's default.
NetBSD has long since migrated to the EABI and doesn't officially support the
OABI anymore. The ABI selection logic in LLVM only actually picks OABI for
NetBSD as a last resort if the EABI isn't selected. That fallback is likely to
be removed in the future. So just remove this support in Zig entirely.
While here, I also removed some leftover 32-bit Arm and 32-bit x86 code for
Apple targets, which are long dead and unsupported by Zig.
Both of these instructions were previously under a special case in
`rvalue` which resulted in every reference to such an instruction adding
a new `ref` instruction. This had the effect that, for instance,
`&a != &a` for parameters. Deduplicating these `ref` instructions was
problematic for different reasons.
For `alloc_inferred`, the problem was that it's not valid to `ref` the
alloc until the allocation has been resolved (`resolve_inferred_alloc`),
but `AstGen.appendBodyWithFixups` would place the `ref` directly after
the `alloc_inferred`. This is solved by bringing
`resolve_inferred_alloc` in line with `make_ptr_const` by having it
*return* the final pointer, rather than modifying `sema.inst_map` of the
original `alloc_inferred`. That way, the `ref` refers to the
`resolve_inferred_alloc` instruction, so is placed immediately after it,
avoiding this issue.
For `param`, the problem is a bit trickier: `param` instructions live in
a body which must contain only `param` instructions, then a
`func{,_inferred,_fancy}`, then a `break_inline`. Moreover, `param`
instructions may be referenced not only by the function body, but also
by other parameters, the return type expression, etc. Each of these
bodies requires separate `ref` instructions. This is solved by pulling
entries out of `ref_table` after evaluating each component of the
function declaration, and appending the refs later on when actually
putting the bodies together. This gives way to another issue: if you
write `fn f(x: T) @TypeOf(x.foo())`, then since `x.foo()` takes a
reference to `x`, this `ref` instruction is now in a comptime context
(outside of the `@TypeOf` ZIR body), so emits a compile error. This is
solved by loosening the rules around `ref` instructions; because they
are not side-effecting, it is okay to allow `ref` of runtime values at
comptime, resulting in a runtime-known value in a comptime scope. We
already apply this mechanism in some cases; for instance, it's why
`runtime_array.len` works in a `comptime` context. In future, we will
want to give similar treatment to many operations in Sema: in general,
it's fine to apply runtime operations at comptime provided they don't
have side effects!
Resolves: #22140
Frame pointers make both debugging and profiling work better, and the overhead
is reportedly 1% or less for typical programs [0]. I think the pros outweigh the
cons here. People who *really* care about that 1% can simply use the
-fomit-frame-pointer option to reclaim it. For ReleaseSmall, though, it makes
sense to omit frame pointers by default for the sake of code size, as we already
strip the binary in this case anyway.
Closes#22161.
[0] https://www.brendangregg.com/blog/2024-03-17/the-return-of-the-frame-pointers.html
