The amount of cross compilation required for these tests was too time-consuming
for how much value they added. test-stack-traces now cover these well enough,
especially as we add more exotic machines to the CI fleet to run native tests.
There were only a few dozen lines of common logic, and they frankly
introduced more complexity than they eliminated. Instead, let's accept
that the implementations of `SelfInfo` are all pretty different and want
to track different state. This probably fixes some synchronization and
memory bugs by simplifying a bunch of stuff. It also improves the DWARF
unwind cache, making it around twice as fast in a debug build with the
self-hosted x86_64 backend, because we no longer have to redundantly go
through the hashmap lookup logic to find the module. Unwinding on
Windows will also see a slight performance boost from this change,
because `RtlVirtualUnwind` does not need to know the module whatsoever,
so the old `SelfInfo` implementation was doing redundant work. Lastly,
this makes it even easier to implement `SelfInfo` on freestanding
targets; there is no longer a need to emulate a real module system,
since the user controls the whole implementation!
There are various other small refactors here in the `SelfInfo`
implementations as well as in the DWARF unwinding logic. This change
turned out to make a lot of stuff simpler!
...and just deal with signal handlers by adding 1 to create a fake
"return address". The system I tried out where the addresses returned by
`StackIterator` were pre-subtracted didn't play nicely with error
traces, which in hindsight, makes perfect sense. This definition also
removes some ugly off-by-one issues in matching `first_address`, so I do
think this is a better approach.
The input path could be cwd-relative, in which case it must be modified
before it is written into the batch script.
Also, remove usage of deprecated `GeneralPurposeAllocator` alias, rename
`allocator` to `gpa`, use unmanaged `ArrayList`.
Previously, the `test-stack-traces` step was essentially just testing
error traces, and even there we didn't have much coverage. This commit
solves that by splitting the "stack trace" tests into two separate
harnesses: the "stack trace" tests are for actual stack traces (i.e.
involving stack unwinding), while the "error trace" tests are
specifically for error return traces.
The "stack trace" tests will test different configurations of:
* `-lc`
* `-fPIE`
* `-fomit-frame-pointer`
* `-fllvm`
* unwind tables (currently disabled)
* strip debug info (currently disabled)
The main goal there is to test *stack unwinding* under different
conditions. Meanwhile, the "error trace" tests will test different
configurations of `-O` and `-fllvm`; the main goal here, aside from
checking that error traces themselves do not miscompile, is to check
whether debug info is still working even in optimized builds. Of course,
aggressive optimizations *can* thwart debug info no matter what, so as
before, there is a way to disable cases for specific targets / optimize
modes.
The program which converts stack traces into a more validatable format
by removing things like addresses (previously `check-stack-trace.zig`,
now `convert-stack-trace.zig`) has been rewritten and simplified. Also,
thanks to various fixes in this branch, several workarounds have become
unnecessary: for instance, we don't need to ignore the function name
printed in stack traces in release modes, because `std.debug.Dwarf` now
uses the correct DIE for inlined functions!
Neither `test-stack-traces` nor `test-error-traces` does general foreign
architecture testing, because it seems that (at least for now) external
executors often aren't particularly good at handling stack tracing
correctly (looking at you, Wine). Generally, they just test the native
target (this matches the old behavior of `test-stack-traces`). However,
there is one exception: when on an x86_64 or aarch64 host, we will also
test the 32-bit version (x86 or arm) if the OS supports it, because such
executables can be trivially tested without an external executor.
Oh, also, I wrote a bunch of stack trace tests. Previously there was,
erm, *one* test in `test-stack-traces` which wasn't for error traces.
Now there are a good few!
Because -fno-llvm is now the default on x86_64-linux, this target was
exactly equivalent to one specified earlier in the matrix. This was
probably just missed when doing the work to enable the self-hosted
backend by default for x86_64.
If the compiler happens to pick `ret = r0`, then this will assemble to
`ag r0, 0` which is obviously not what we want. Using `a` instead of `r` will
ensure that we get an appropriate address register, i.e. `r1` through `r15`.
Re-enable pie_linux for s390x-linux which was disabled in
ed7ff0b693.
Alex Rønne Petersen