Re-commit r319490 "XOR the frame pointer with the stack cookie when protecting the stack"
The patch originally broke Chromium (crbug.com/791714) due to its failing to
specify that the new pseudo instructions clobber EFLAGS. This commit fixes
that.
> Summary: This strengthens the guard and matches MSVC.
>
> Reviewers: hans, etienneb
>
> Subscribers: hiraditya, JDevlieghere, vlad.tsyrklevich, llvm-commits
>
> Differential Revision: https://reviews.llvm.org/D40622
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@319824
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96231b3b80d8