[PATCH] D92695: [X86ISelLowering] don't emit frame pointers for eflags intrinsics.

Fri Dec 4 14:57:56 PST 2020

nickdesaulniers added a comment.

In D92695#2434973 <https://reviews.llvm.org/D92695#2434973>, @craig.topper wrote:

> What prevents overwriting something in the red zone?

I don't follow.  How does the kernel prevent overwriting something in the red zone?  I don't know, https://lore.kernel.org/lkml/CALCETrXUaeNUbkQSeMPpPKWDBCEpqX1gLgkv2G9zLeeYMjK8VQ@mail.gmail.com/ was the brief conversation we had on LKML, but I'd have to talk with the x86 maintainers who would know more. Andy Lutomirski seems to imply the kernel may be broken in that regard.

But I also think that is orthogonal to these builtins and frame pointers, or at least I fail to see the relation.

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https://reviews.llvm.org/D92695