On Sun, Mar 06, 2016 at 10:39:19PM +0100, Uros Bizjak wrote:
> Attached patch prevents red-zone with -fPIC for leaf functions on
> i686. The idea is to mark when set_got is expanded as a call to a pc
> thunk, and use this flag to prevent red-zone in the current function.
>
> Please note that using red-zone with i686 violates all known ABIs, but
> some future ABI can trip on this limitation. The failure mode is quite
> tricky, so IMO it warrants a couple of lines as a safety net.
>
> The testcase is not suitable for the testsuite (it uses -mred-zone for
> i686 target), but I have checked that the testcase works OK when
> compiled with the patched compiler even when -mred-zone is used
> together with -fPIC.
>
> Jakub, HJ - what do you think?
LGTM. Have you checked other possibilities of red-zone violations from the
compiler generated stuff? I mean -p, -mfentry, TLS (both GNU and GNU2)?
Signals/interrupts and inline asm is something that the user is responsible
if he enables -mred-zone, but the above probably are not.
Jakub
