Thanks a lot for your review. I will commit the patch soon.
Qing > On Dec 2, 2020, at 12:27 PM, Jeff Law <l...@redhat.com> wrote: > > > > On 12/2/20 9:32 AM, Qing Zhao wrote: >> >>> So we are clearing the x87 registers with that option. Hence the change >>> in reg-stack behavior. I'm a bit surprised by this as I don't see >>> clearing the x87 registers as particularly helpful from a security >>> standpoint. But I haven't followed that discussion closely. >> Even with the option -fzero-call-used-regs=used-gpr (without clearing any >> x87 registers), >> We have the same compiler time error. >> >> The first thing that the new pass “zero_call_used_regs” does is: >> >> df_analyze(); > OK. So that's the key issue, until now nothing has really cared about > the DF state after reg-stack, but the pass to zero registers does. I > had the order backwards in my head with register clearing happening > before regstack. Hence my significant confusion about why things were > suddenly going wrong. > > The patch is OK. Thanks for patiently walking me through this. > > jeff >