[llvm-dev] Discuss about the LLVM SW mitigation to Jump Conditional Code Erratum

[Zhang, Annita via llvm-dev]

Yes, we will test it. I think -ffunction-sections will increase the section numbers, but not the function numbers. The code size may be increased because every code section has to be aligned with 32-byte for the padding. 


-----Original Message-----
From: Fāng-ruì Sòng <maskray at google.com> 
Sent: Friday, December 6, 2019 4:21 PM
To: Zhang, Annita <annita.zhang at intel.com>
Cc: llvm-dev at lists.llvm.org; Craig Topper <craig.topper at gmail.com>
Subject: Re: [llvm-dev] Discuss about the LLVM SW mitigation to Jump Conditional Code Erratum

On Wed, Dec 4, 2019 at 8:41 AM Craig Topper via llvm-dev <llvm-dev at lists.llvm.org> wrote:
>
> Annita, do you have measurements with inserting NOPs instead of redundant segment prefixes. The code review was asking for performance data to show that prefixes are better than NOPs.
>
> ~Craig

Also -ffunction-sections. With more sections, it may be easier to exhibit non-convergence problems. The compile time may not be slowed much because functions will be smaller. The code size may increase if more sections need over-alignment.