[all-commits] [llvm/llvm-project] 9d9e49: [x86][seses] Add clang flag; Use lvi-cfi with seses

[zbrid via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 9d9e499840af670b9644af77ce846c52085c23a1
      https://github.com/llvm/llvm-project/commit/9d9e499840af670b9644af77ce846c52085c23a1
  Author: Zola Bridges <zbrid at google.com>
  Date:   2020-07-07 (Tue, 07 Jul 2020)

  Changed paths:
    M clang/docs/ClangCommandLineReference.rst
    M clang/include/clang/Driver/Options.td
    M clang/lib/Driver/ToolChains/Arch/X86.cpp
    M clang/test/Driver/x86-target-features.c
    M llvm/lib/Target/X86/X86.td
    M llvm/lib/Target/X86/X86SpeculativeExecutionSideEffectSuppression.cpp
    M llvm/lib/Target/X86/X86Subtarget.h
    M llvm/test/CodeGen/X86/speculative-execution-side-effect-suppression.ll

  Log Message:
  -----------
  [x86][seses] Add clang flag; Use lvi-cfi with seses

This patch creates a clang flag to enable SESES. This flag also ensures that
lvi-cfi is on when using seses via clang.

SESES should use lvi-cfi to mitigate returns and indirect branches.

The flag to enable the SESES functionality only without lvi-cfi is now
-x86-seses-enable-without-lvi-cfi to warn users part of the mitigation is not
enabled if they use this flag. This is useful in case folks want to see the
cost of SESES separate from the LVI-CFI.

Reviewed By: sconstab

Differential Revision: https://reviews.llvm.org/D79910