std.debug: completely disable FP-based unwinding on mips

This commit is contained in:
Alex Rønne Petersen 2025-10-04 04:10:00 +02:00
parent 30f5258fe6
commit e6e4792a58

View File

@ -855,6 +855,18 @@ const StackIterator = union(enum) {
}
}
/// Some architectures make FP unwinding too impractical. For example, due to its very silly ABI
/// design decisions, it's not possible to do generic FP unwinding on MIPS; we would need to do
/// a complicated code scanning algorithm instead. At that point, we may as well just use DWARF.
const fp_unwind_is_impossible = switch (builtin.cpu.arch) {
.mips,
.mipsel,
.mips64,
.mips64el,
=> true,
else => false,
};
/// <https://developer.apple.com/documentation/xcode/writing-arm64-code-for-apple-platforms#Respect-the-purpose-of-specific-CPU-registers>
const fp_unwind_is_safe = builtin.cpu.arch == .aarch64 and builtin.os.tag.isDarwin();
@ -879,7 +891,14 @@ const StackIterator = union(enum) {
// immediately regardless of anything. But FPs could also be omitted from a different
// linked object, so it's not guaranteed to be safe, unless the target specifically
// requires it.
.fp => abi_requires_backchain or (!builtin.omit_frame_pointer and (fp_unwind_is_safe or allow_unsafe)),
.fp => s: {
if (fp_unwind_is_impossible) break :s false;
if (abi_requires_backchain) break :s true;
if (builtin.omit_frame_pointer) break :s false;
if (fp_unwind_is_safe) break :s true;
if (allow_unsafe) break :s true;
break :s false;
},
};
}