[Bug target/62281] gcc doesn't conform to Solaris 32-bit ABI by expecting 16-byte stack alignment

["ro at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62281

Rainer Orth <ro at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ro at gcc dot gnu.org
   Target Milestone|---                         |5.0

--- Comment #6 from Rainer Orth <ro at gcc dot gnu.org> ---
I've been seeing the same issue in PR middle-end/61949, but only on Solaris 10,
not S11, and the failures have been intermittent (i.e. happened during one
bootstrap,
but were gone a week later).

Regarding

> I believe the problem was fixed for the limited case of Solaris 9 x86 in bug 
> 60107. However, the analysis for this fix seems slightly off. It infers that,
> because Solaris 10 creates outgoing thread stacks aligned on 16 bytes, the
> 32-bit ABI has changed to 16-byte stack alignment on this platform, which isn't
> correct.

I believe the i386 psABI is irrelevant here: while it requires word alignment,
it
doesn't preclude that Solaris guarantees a stricter alignment, which from what
I've seen both S10 and S11 do.

> I suggest -mincoming-stack-boundary=2 should be the default for all 32-bit
> Solaris binaries.

Before making any changes in this area, I'd like word from the responsible libc
engineer (Roger Faulkner probably) what various Solaris versions do and don't
guarantee.

  Rainer