musl and glibc both specify r0 as an output register because its value
may be overwritten by system calls. As with the updates for 64-bit
PowerPC in the previous commit, this commit brings Zig's syscall
functions for 32-bit PowerPC in line with musl and glibc by adding r0 to
the list of clobbers. (Listing r0 as both an input and a clobber is as
close as we can get to musl, which declares it as a "+r" read-write
output, since Zig doesn't support multiple outputs or the "+"
specifier.)
On powerpc64le Linux, the registers used for passing syscall parameters
(r4-r8, as well as r0 for the syscall number) are volatile, or
caller-saved. However, Zig's syscall wrappers for this architecture do
not include all such registers in the list of clobbers, leading the
compiler to assume these registers will maintain their values after the
syscall completes.
In practice, this resulted in a segfault when allocating memory with
`std.heap.SmpAllocator`, which calls `std.os.linux.sched_getaffinity`.
The third parameter to `sched_getaffinity` is a pointer to a `cpu_set_t`
and is stored in register r5. After the syscall, the code attempts to
access data in the `cpu_set_t`, but because the compiler doesn't realize
the value of r5 may have changed, it uses r5 as the memory address, which
in practice resulted in a memory access at address 0x8.
This commit adds all volatile registers to the list of clobbers.
This is not meant to be a long-term solution, but it's the easiest thing
to get working quickly at the moment. The main intention of this hack is
to allow more tests to be enabled. By the time the coff linker is far
enough along to be enabled by default, this will no longer be required.
e.g. `x86_64-windows.win10...win11_dt-gnu` -> `x86_64-windows-gnu`
When the OS version is the default this is redundant with checking the
default in the standard library.
* `futex2_waitv` always takes a 64-bit timespec. Perhaps the
`kernel_timespec` should be renamed `timespec64`? Its used in iouring,
too.
* Add `packed struct` for futex v2 flags and parameters.
* Add very basic "tests" for the futex v2 syscalls (just to ensure the
code compiles).
* Update the stale or broken comments. (I could also just delete these
they're not really documenting Zig-specific behavior.)
Given that the futex2 APIs are not used by Zig's library (they're a bit
too new), and the fact that these are very specialized syscalls, and they
currently provide no benefit over the existing v1 API, I wonder if instead
of fixing these up, we should just replace them with a stub that says 'use
a 3rd party library'.
This is necessary in two cases:
* On POSIX, the exe path (`argv[0]`) must contain a path separator
* Some programs might treat a file named e.g. `-foo` as a flag, which
can be avoided by passing `./-foo`
Rather than detecting these two cases, just always include the prefix;
there's no harm in it.
Also, if the cwd is specified, include it in the manifest. If the user
has set the cwd of a Run step, it is clearly because this affects the
behavior of the executable somehow, so that cwd path should be a part of
the step's manifest.
Resolves: #24216
Cmake by default adds the `/RTC1` compiler flag for debug builds.
However, this causes C code that conforms to the C standard and has
well-defined behavior to trap. Here I've updated CMAKE to use the more
lenient `/RTCs` by default which removes the uninitialized variable checks
but keeps the stack error checks.
* Use `packed struct` for flags arguments. So, instead of
`linux.FUTEX.WAIT` use `.{ .cmd = .WAIT, .private = true }`
* rename `futex_wait` and `futex_wake` which didn't actually specify
wait/wake, as `futex_3arg` and `futex_4arg` (as its the number
of parameters that is different, the `op` is whatever is specified.
* expose the full six-arg flavor of the syscall (for some of the advanced
ops), and add packed structs for their arguments.
* Use a `packed union` to support the 4th parameter which is sometimes a
`timespec` pointer, and sometimes a `u32`.
* Add tests that make sure the structure layout is correct and that the
basic argument passing is working (no actual futexes are contended).
Also add a standalone test which covers the `-fentry` case. It does this
by performing two reproducible compilations which are identical other
than having different entry points, and checking whether the emitted
binaries are identical (they should *not* be).
Resolves: #23869
`std.Build.Step.ConfigHeader` emits a *directory* containing a config
header under a given sub path, but there's no good way to actually
access that directory as a `LazyPath` in the configure phase. This is
silly; it's perfectly valid to refer to that directory, perhaps to
explicitly pass as a "-I" flag to a different toolchain invoked via a
`Step.Run`. So now, instead of the `GeneratedFile` being the actual
*file*, it should be that *directory*, i.e. `cache/o/<digest>`. We can
then easily get the *file* if needed just by using `LazyPath.path` to go
"deeper", which there is a helper function for.
The legacy `getOutput` function is now a deprecated alias for
`getOutputFile`, and `getOutputDir` is introduced.
`std.Build.Module.IncludeDir.appendZigProcessFlags` needed a fix after
this change, so I took the opportunity to refactor it a little. I was
looking at this function while working on ziglang/translate-c yesterday
and realised it could be expressed much more simply -- particularly
after the `ConfigHeader` change here.
I had to update the test `standalone/cmakedefine/` -- it turns out this
test was well and truly reaching into build system internals, and doing
horrible not-really-allowed stuff like overriding the `makeFn` of a
`TopLevelStep`. To top it all off, the test forgot to set
`b.default_step` to its "test" step, so the test never even ran. I've
refactored it to follow accepted practices and to actually, like, work.
This function is sometimes used to assume a canonical representation of
a path. However, when the `Path` referred to `root_dir` itself, this
function previously resolved `sub_path` to ".", which is incorrect; per
doc comments, it should set `sub_path` to "".
This fix ultimately didn't solve what I was trying to solve, though I'm
still PRing it, because it's still *correct*. The background to this
commit is quite interesting and worth briefly discussing.
I originally worked on this to try and fix a bug in the build system,
where if the root package (i.e. the one you `zig build`) depends on
package X which itself depends back on the root package (through a
`.path` dependency), invalid dependency modules are generated. I hit
this case working on ziglang/translate-c, which wants to depend on
"examples" (similar to the Zig compiler's "standalone" test cases) which
themselves depend back on the translate-c package. However, after this
patch just turned that error into another, I realised that this case
simply cannot work, because `std.Build` needs to eagerly execute build
scripts at `dependency` calls to learn which artifacts, modules, etc,
exist.
...at least, that's how the build system is currently designed. One can
imagine a world where `dependency` sort of "queues" the call, `artifact`
and `module` etc just pretend that the thing exists, and all configure
functions are called non-recursively by the runner. The downside is that
it becomes impossible to query state set by a dependency's configure
script. For instance, if a dependency exposes an artifact, it would
become impossible to get that artifact's resolved target in the
configure phase. However, as well as allowing recursive package imports
(which are certainly kinda nifty), it would also make lazy dependencies
far more useful! Right now, lazy dependencies only really work if you
use options (`std.Build.option`) to block their usage, since any call to
`lazyDependency` causes the dependency to be fetched. However, if we
made this change, lazy dependencies could be made far more versatile by
only fetching them *if the final step plan requires them*. I'm not 100%
sure if this is a good idea or not, but I might open an issue for it
soon.
There will be more call sites to `preparePanicId` as we transition away
from safety checks in Sema towards safety checked instructions; it's
silly for them to all have this clunky usage.
This safety check was completely broken; it triggered unchecked illegal
behavior *in order to implement the safety check*. You definitely can't
do that! Instead, we must explicitly check the boundaries. This is a
tiny bit fiddly, because we need to make sure we do floating-point
rounding in the correct direction, and also handle the fact that the
operation truncates so the boundary works differently for min vs max.
Instead of implementing this safety check in Sema, there are now
dedicated AIR instructions for safety-checked intfromfloat (two
instructions; which one is used depends on the float mode). Currently,
no backend directly implements them; instead, a `Legalize.Feature` is
added which expands the safety check, and this feature is enabled for
all backends we currently test, including the LLVM backend.
The `u0` case is still handled in Sema, because Sema needs to check for
that anyway due to the comptime-known result. The old safety check here
was also completely broken and has therefore been rewritten. In that
case, we just check for 'abs(input) < 1.0'.
I've added a bunch of test coverage for the boundary cases of
`@intFromFloat`, both for successes (in `test/behavior/cast.zig`) and
failures (in `test/cases/safety/`).
Resolves: #24161
These conversion routines accept a `round` argument to control how the
result is rounded and return whether the result is exact. Most callers
wanted this functionality and had hacks around it being missing.
Also delete `std.math.big.rational` because it was only being used for
float conversion, and using rationals for that is a lot more complex
than necessary. It also required an allocator, whereas the new integer
routines only need to be passed enough memory to store the result.
If you write an if expression in mem.doNotOptimizeAway like
doNotOptimizeAway(if (ix < 0x00100000) x / 0x1p120 else x + 0x1p120);,
FCSEL instruction is used on AArch64.
FCSEL instruction selects one of the two registers according to
the condition and copies its value.
In this example, `x / 0x1p120` and `x + 0x1p120` are expressions
that raise different floating-point exceptions.
However, since both are actually evaluated before the FCSEL
instruction, the exception not intended by the programmer may
also be raised.
To prevent FCSEL instruction from being used here, this commit
splits doNotOptimizeAway in two.
and also rename `advancedPrint` to `bufferedPrint` in the zig init templates
These are left overs from my previous changes to zig init.
The new templating system removes LITNAME because the new restrictions on package names make it redundant with NAME, and the use of underscores for marking templated identifiers lets us template variable names while still keeping zig fmt happy.
Did you know that allocators reuse addresses? If not, then don't feel
bad, because apparently I don't either! This dumb mistake was probably
responsible for the CI failures on `master` yesterday.
I messed up atomic orderings on this variable because they changed in a
local refactor at some point. We need to always release on the store and
acquire on the loads so that a linker thread observing `.ready` sees the
stored MIR.
Because any `LazyPath` might be resolved to a relative path, it's
incorrect to pass that directly to a child process whose cwd might
differ. Instead, if the child has an overriden cwd, we need to convert
such paths to be relative to the child cwd using `std.fs.path.relative`.
File arguments added to `std.Build.Step.Run` with e.g. `addFileArg` are
not necessarily passed as absolute paths. It used to be the case that
they were as a consequence of an unnecessary path conversion done by the
frontend, but this no longer happens, at least not always, so these
tests were sometimes failing when run locally. Therefore, the standalone
tests must handle cwd-relative CLI paths correctly.
