[PATCH] D41723: Introduce the "retpoline" x86 mitigation technique for variant #2 of the speculative execution vulnerabilities disclosed today, specifically identified by CVE-2017-5715, "Branch Target Injection", and is one of the two halves to Spectre..

[Roger via Phabricator via llvm-commits]

royger added a comment.

AFAICT this change doesn't allow to use different indirect thunks, gcc allows such usage with the -mindirect-branch=thunk-extern/-mindirect-branch-register options. The following patches for example allow Xen to choose the optimal thunk depending on the processor:

https://lists.xenproject.org/archives/html/xen-devel/2018-01/msg00112.html
https://lists.xenproject.org/archives/html/xen-devel/2018-01/msg00118.html


https://reviews.llvm.org/D41723