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
The main change here is to partition tracked instructions found within a
declaration. It's very unlikely that, for instance, a `struct { ... }`
type declaration was intentionally turned into a reification or an
anonymous initialization, so it makes sense to track things in a few
different arrays.
In particular, this fixes an issue where a `func` instruction could
wrongly be mapped to something else if the types of function parameters
changed. This would cause huge problems further down the pipeline; we
expect that if a `declaration` is tracked, and it previously contained a
`func`/`func_inferred`/`func_fancy`, then this instruction is either
tracked to another `func`/`func_inferred`/`func_fancy` instruction, or
is lost.
Also, this commit takes the opportunity to rename the functions actually
doing this logic. `Zir.findDecls` was a name that might have made sense
at some point, but nowadays, it's definitely not finding declarations,
and it's not *exclusively* finding type declarations. Instead, the point
is to find instructions which we want to track; hence the new name,
`Zir.findTrackable`.
Lastly, a nice side effect of partitioning the output of `findTrackable`
is that `Zir.declIterator` no longer needs to accept input instructions
which aren't type declarations (e.g. `reify`, `func`).
This commit enhances AstGen to introduce a form of error resilience
which allows valid ZIR to be emitted even when AstGen errors occur.
When a non-fatal AstGen error (e.g. `appendErrorNode`) occurs, ZIR
generation is not affected; the error is added to `astgen.errors` and
ultimately to the errors stored in `extra`, but that doesn't stop us
getting valid ZIR. Fatal AstGen errors (e.g. `failNode`) are a bit
trickier. These errors return `error.AnalysisFail`, which is propagated
up the stack. In theory, any parent expression can catch this error and
handle it, continuing ZIR generation whilst throwing away whatever was
lost. For now, we only do this in one place: when creating declarations.
If a call to `fnDecl`, `comptimeDecl`, `globalVarDecl`, etc, returns
`error.AnalysisFail`, the `declaration` instruction is still created,
but its body simply contains the new `extended(astgen_error())`
instruction, which instructs Sema to terminate semantic analysis with a
transitive error. This means that a fatal AstGen error causes the
innermost declaration containing the error to fail, but the rest of the
file remains intact.
If a source file contains parse errors, or an `error.AnalysisFail`
happens when lowering the top-level struct (e.g. there is an error in
one of its fields, or a name has multiple declarations), then lowering
for the entire file fails. Alongside the existing `Zir.hasCompileErrors`
query, this commit introduces `Zir.loweringFailed`, which returns `true`
only in this case.
The end result here is that files with AstGen failures will almost
always still emit valid ZIR, and hence can undergo semantic analysis on
the parts of the file which are (from AstGen's perspective) valid. This
is a noteworthy improvement to UX, but the main motivation here is
actually incremental compilation. Previously, AstGen failures caused
lots of semantic analysis work to be thrown out, because all `AnalUnit`s
in the file required re-analysis so as to trigger necessary transitive
failures and remove stored compile errors which would no longer make
sense (because a fresh compilation of this code would not emit those
errors, as the units those errors applied to would fail sooner due to
referencing a failed file). Now, this case only applies when a file has
severe top-level errors, which is far less common than something like
having an unused variable.
Lastly, this commit changes a few errors in `AstGen` to become fatal
when they were previously non-fatal and vice versa. If there is still a
reasonable way to continue AstGen and lower to ZIR after an error, it is
non-fatal; otherwise, it is fatal. For instance, `comptime const`, while
redundant syntax, has a clear meaning we can lower; on the other hand,
using an undeclared identifer has no sane lowering, so must trigger a
fatal error.
It doesn't appear that targeting bridgeOS is meaningfully supported by Apple.
Even LLVM/Clang appear to have incomplete support for it, suggesting that Apple
never bothered to upstream that support. So there's really no sense in us
pretending to support this.
If present, these headers are usable even when compiling for older C language
versions.
Most notably, this enables zig.h atomics to work with slimcc and TinyCC in C99
mode (and earlier).
The freestanding and other OS targets by default need to just @trap in the
default Panic implementation.
And `isValidMemory` won't work with freestanding or other targets.
Update the unwind_freestanding.zig test case to also run on the 'other' OS
target, too. This should keep the Zig's stacktrace generation from
regressing on the standalone targets.
