Chandler Carruth 0e44a1b235 [x86/SLH] Add a real Clang flag and LLVM IR attribute for Speculative ... Load Hardening. Wires up the existing pass to work with a proper IR attribute rather than just a hidden/internal flag. The internal flag continues to work for now, but I'll likely remove it soon. Most of the churn here is adding the IR attribute. I talked about this Kristof Beyls and he seemed at least initially OK with this direction. The idea of using a full attribute here is that we *do* expect at least some forms of this for other architectures. There isn't anything *inherently* x86-specific about this technique, just that we only have an implementation for x86 at the moment. While we could potentially expose this as a Clang-level attribute as well, that seems like a good question to defer for the moment as it isn't 100% clear whether that or some other programmer interface (or both?) would be best. We'll defer the programmer interface side of this for now, but at least get to the point where the feature can be enabled without relying on implementation details. This also allows us to do something that was really hard before: we can enable *just* the indirect call retpolines when using SLH. For x86, we don't have any other way to mitigate indirect calls. Other architectures may take a different approach of course, and none of this is surfaced to user-level flags. Differential Revision: https://reviews.llvm.org/D51157 llvm-svn: 341363		2018-09-04 12:38:00 +00:00
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Reader	[x86/SLH] Add a real Clang flag and LLVM IR attribute for Speculative	2018-09-04 12:38:00 +00:00
Writer	[x86/SLH] Add a real Clang flag and LLVM IR attribute for Speculative	2018-09-04 12:38:00 +00:00
CMakeLists.txt
LLVMBuild.txt