Hi Jeff, Do you have any further comments about this patch ?
Thanks, Yanzhang > -----Original Message----- > From: Jeff Law <jeffreya...@gmail.com> > Sent: Friday, July 21, 2023 12:11 PM > To: Kito Cheng <kito.ch...@gmail.com>; Wang, Yanzhang > <yanzhang.w...@intel.com> > Cc: gcc-patches@gcc.gnu.org; juzhe.zh...@rivai.ai; kito.ch...@sifive.com; > Li, Pan2 <pan2...@intel.com> > Subject: Re: [PATCH v3] RISCV: Add -m(no)-omit-leaf-frame-pointer support. > > > > On 7/20/23 21:49, Kito Cheng wrote: > > LGTM, I think long jump is another issue and making ra become a fixed > > register will escalate to an ABI issue, so that should not be a > > blocker for this patch. > I'll take a look tomorrow, but I'm supportive of what Yanzhang is trying to > do in principle. I've got a few hot items to deal with tonight though. > > WRT making $ra fixed. In practice fixing a register just takes it out of > the pool of things available to the allocator. Furthermore $ra is always > considered clobbered at call sites. So while one could view it as an ABI > change, it's not one that's actually observable in practice. > I suspect that's one of the reasons why $ra is used by the assembler in > this manner -- it minimizes both the ABI and performance impacts. > > jeff
