This change enhances stack trace output to include a note that debug info was missing,
and therefore the stack trace may not be accurate. For example, if the user is using a libc
compiled with -fomit-frame-pointer and doesn't have debug symbols installed, any traces
that begin in a libc function may not unwind correctly. This allows the user to notice this and
potentially install debug symbols to improve the output.
I had accidentally regressed support for -gdwarf in 461fb499f3 when I changed the logic to
use the already-mapped exe/dll image instead of loading it from disk. The string table is mapped as all zeroes by the loader,
so if a section header's name is longer than 8 bytes (like the ones generated by -gdwarf), then the name can't be read.
Now, if any section headers require the string table, the file is mapped from disk.
windows: Add NtCreateSection/NtMapViewOfSection/NtUnmapViewOfSection
- Fix unwindFrame using the previous FDE row instead of the current one
- Handle unwinding through noreturn functions
- Add x86-linux getcontext
- Fixup x86_64-linux getcontext not restoring the fp env
- Fix start_addr filtering on x86-windows
- .eh_frame_hdr contains a binary-searchable data structure for finding an FDE. If present, we can use this
section to avoid having to parse the entire FDE/CIE list in the binary, instead only entries that are actually
required for unwinding are read.
- rework the inputs pc-relative pointer decoding to support both already-mapped sections as well as sections
mapped from a file
- store the VirtualMachine on UnwindContext so the allocations can be reused
Some distributions (ie. Ubuntu) have their libc debug
info in separate files. This change allows the stack walking
code to read that debug info.
- add support for reading compressed ELF sections
- support reading the build-id from the elf headers in order to lookup external debug info
- support reading the .gnu_debuglink section to look up external debug info
Most of this migration was performed automatically with `zig fmt`. There
were a few exceptions which I had to manually fix:
* `@alignCast` and `@addrSpaceCast` cannot be automatically rewritten
* `@truncate`'s fixup is incorrect for vectors
* Test cases are not formatted, and their error locations change
Also get rid of the TTY wrapper struct, which was exlusively used as a
namespace - this is done by the tty.zig root struct now.
detectTTYConfig has been renamed to just detectConfig, which is enough
given the new namespace. Additionally, a doc comment had been added.
* docs(std.math): elaborate on difference between absCast and absInt
* docs(std.rand.Random.weightedIndex): elaborate on likelihood
I think this makes it easier to understand.
* langref: add small reminder
* docs(std.fs.path.extension): brevity
* docs(std.bit_set.StaticBitSet): mention the specific types
* std.debug.TTY: explain what purpose this struct serves
This should also make it clearer that this struct is not supposed to provide unrelated terminal manipulation functionality such as setting the cursor position or something because terminals are complicated and we should keep this struct simple and focused on debugging.
* langref(package listing): brevity
* langref: explain what exactly `threadlocal` causes to happen
* std.array_list: link between swapRemove and orderedRemove
Maybe this can serve as a TLDR and make it easier to decide.
* PrefetchOptions.locality: clarify docs that this is a range
This confused me previously and I thought I can only use either 0 or 3.
* fix typos and more
* std.builtin.CallingConvention: document some CCs
* langref: explain possibly cryptic names
I think it helps knowing what exactly these acronyms (@clz and @ctz) and
abbreviations (@popCount) mean.
* variadic function error: add missing preposition
* std.fmt.format docs: nicely hyphenate
* help menu: say what to optimize for
I think this is slightly more specific than just calling it
"optimizations". These are speed optimizations. I used the word
"performance" here.
- walk the stack via the method that is aware of unwind info (fixes x86_64 / aarch64 traces)
- enhance the output for frames where the debug info isn't available by printing the module name
This fixes a bug in std.net caused during the introduction of
meta.assumeSentinel due to the unfortunate semantics of mem.span()
This leaves only 3 remaining uses of meta.assumeSentinel() in the
standard library, each of which could be a simple @ptrCast([*:0]T, foo)
instead. I think this function should likely be removed.
windows: add RtlCaptureContext, RtlLookupFunctionEntry, RtlVirtualUnwind and supporting types
windows: fix alignment of CONTEXT structs to match winnt.h as required by RtlCaptureContext (fxsave instr)
windows aarch64: fix __chkstk being defined twice if libc is not linked on msvc
Co-authored-by: Jakub Konka <kubkon@jakubkonka.com>
