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std.debug.SelfInfo.MachO: don't restore vector registers during unwinding

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We know that these are unsupported and irrelevant for unwinding, so don't fail
the unwind attempt trying to read/write them for no ultimate purpose.
This commit is contained in:
Alex Rønne Petersen 2025-10-07 09:33:42 +02:00
parent c23a5ccd19
commit a06db282c7
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1 changed files with 5 additions and 15 deletions
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20
lib/std/debug/SelfInfo/MachO.zig
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@ -401,21 +401,11 @@ fn unwindFrameInner(si: *SelfInfo, gpa: Allocator, context: *UnwindContext) !usi
}
}
inline for (@typeInfo(@TypeOf(frame.d_reg_pairs)).@"struct".fields, 0..) |field, i| {
if (@field(frame.d_reg_pairs, field.name) != 0) {
// Only the lower half of the 128-bit V registers are restored during unwinding
{
const dest: *align(1) usize = @ptrCast(try context.cpu_state.dwarfRegisterBytes(64 + 8 + i));
dest.* = @as(*const usize, @ptrFromInt(reg_addr)).*;
}
reg_addr += @sizeOf(usize);
{
const dest: *align(1) usize = @ptrCast(try context.cpu_state.dwarfRegisterBytes(64 + 9 + i));
dest.* = @as(*const usize, @ptrFromInt(reg_addr)).*;
}
reg_addr += @sizeOf(usize);
}
}
// We intentionally skip restoring `frame.d_reg_pairs`; we know we don't support
// vector registers in the AArch64 `cpu_context` anyway, so there's no reason to
// fail a legitimate unwind just because we're asked to restore the registers here.
// If some weird/broken unwind info tells us to read them later, we will fail then.
reg_addr += 16 * @as(usize, @popCount(@as(u4, @bitCast(frame.d_reg_pairs))));
const new_ip = @as(*const usize, @ptrFromInt(ip_ptr)).*;
const new_fp = @as(*const usize, @ptrFromInt(fp)).*;