On Mon, 2026-02-02 at 19:57 -0800, H. Peter Anvin wrote:
> That hack dates back from before the signal frame extension. It is no
> longer necessary.
Unfortunately at least it seems libgcc unwinder does not handle the
signal frame extension properly. The code reads:
fde = _Unwind_Find_FDE (context->ra + _Unwind_IsSignalFrame (context) - 1,
&context->bases);
if (fde == NULL)
{
#ifdef MD_FALLBACK_FRAME_STATE_FOR
/* Couldn't find frame unwind info for this function. Try a
target-specific fallback mechanism. This will necessarily
not provide a personality routine or LSDA. */
return MD_FALLBACK_FRAME_STATE_FOR (context, fs);
#else
return _URC_END_OF_STACK;
#endif
}
fs->pc = context->bases.func;
cie = get_cie (fde);
insn = extract_cie_info (cie, context, fs);
Thus, it indeed attempts to avoid subtracting 1 for a signal frame, but
... _Unwind_IsSignalFrame (context) actually extracts a flag in context
which will only be raised up by extract_cie_info.
Or am I missing something here?
--
Xi Ruoyao <[email protected]>
