[PATCH] D36388: [X86][SandyBridge] Additional updates to the SNB instructions scheduling information

Wed Aug 16 22:56:31 PDT 2017

gadi.haber added a comment.

I see. Code alignment in X86 is indeed an issue. 
There are currently two pending reviews for patches that start providing a fix for the code alignment issue in X86.
The reviews are in a pending state for quite some time now. 
Maybe we can give them higher priority and get them in?

The first patch (at https://reviews.llvm.org/D34393) is an NFC that provides the needed infrastructure for inserting padding code (NOPs) aimed only for performance stability. This will give us the ability to insert fixes for cases of regression caused by code alignment effects.

The second patch (at https://reviews.llvm.org/D34396) already uses the above infrastructure to handle the first case of regressions caused by misprediction of branches to same target addresses in a loop = which are resolved by appropriate code padding.

Repository:
  rL LLVM

https://reviews.llvm.org/D36388