For unwinding purposes, we don't care about unsupported registers. Yet because
we added these rules to the cache entry, we'd later try to evaluate them and
thus fail the unwind attempt for no good reason. They'd also take up cache rule
slots that would be better spent on actually relevant registers.
Note that any attempt to read unsupported registers during unwinding will still
fail the unwind attempt as expected.
The previous version (ported from musl) used bit-by-bit calculations and was slow, but the current version (also ported from musl) uses lookup tables combined with Goldschmidt iterations to significantly improve the speed.
* ELF v1 on powerpc64 is only barely kept on life support in a couple of Linux
distros. I don't anticipate that this will last much longer.
* Most of the Linux world has moved to powerpc64le which requires ELF v2.
* Some Linux distros have even started supporting powerpc64 with ELF v2.
* The BSD world has long since moved to ELF v2.
* We have no actual linking support for ELF v1.
* ELF v1 had confused DWARF register mappings which is becoming a problem in
our DWARF code in std.debug.
It's clear that ELF v1 is on its way out, and we never fully supported it
anyway. So let's not waste any time or energy on it going forward.
closes#5927
FreeBSD doesn't support the same number of platforms as Linux, and even then,
only has usermode emulation for a subset of its supported platforms.
NetBSD's usermode emulation support is apparently just broken at the moment.
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.
For the supported COFF machine types of X64 (x86_64), I386 (x86), ARMNT (thumb), and ARM64 (aarch64), this new Zig implementation results in byte-for-byte identical .lib files when compared to the previous LLVM-backed implementation.
Previously, `setAlignment` would set the value to 1 fewer than it should, so if you were intending to set alignment to 8 bytes, it would actually set it to 4 bytes, etc.
This enables depth-related use cases without any dependency on the Walker's internal stack which doesn't always pertain to the actual depth of the current entry (i.e. recursing into a directory immediately affects the stack).
Some decision-making might depend on the level of the traversal, so
it makes sense to expose depth here since it's stable, and not in the
automatic walker where it's not.
