This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [PATCH 1/3] [builtins] Generic support for __builtin_load_no_speculate()
On 01/07/2018 07:20 PM, Bill Schmidt wrote:
> Hi Richard,
>
> Unfortunately, I don't see any way that this will be useful for the ppc targets. We don't
> have a way to force resolution of a condition prior to continuing speculation, so this
> will just introduce another comparison that we would speculate past. For our mitigation
> we will have to introduce an instruction that halts all speculation at that point, and place
> it in front of all dangerous loads. I wish it were otherwise.
So could you have an expander for __builtin_load_no_speculate that just
emits the magic insn that halts all speculation and essentially ignores
the additional stuff that __builtin_load_no_speculate might be able to
do on other platforms?
jeff