[PATCH] D54629: [AArch64] Add command-line option for SSBS

[Pablo Barrio via Phabricator via llvm-commits]

pbarrio added a comment.

Thank you for the review, Sam :)

FeatureSpecRestrict was really enabling two features, not one, both related to speculation restriction in the CPU. These features were the Software Context Number registers (SCXTNUM_ELx) and the Speculative Store Bypass Safe (SSBS) bit. We just added them into the same back-end feature initially because they are mandatory in 8.5 (i.e. no command line option required in 8.5). However, these security features are optional down to 8.0, so we want to allow them separately via a command-line option. This patch just spawns SSBS out of SpecRestrict.

Good point about the Clang patch. No changes inside clang itself (it picks up everything from tablegen directly) but I've added some testing. Now available for review at https://reviews.llvm.org/D54961. Feel free to point out there if I missed something.


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  rL LLVM

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https://reviews.llvm.org/D54629