[PATCH] D72220: [X86] Support function attribute "patchable-function-entry"

[Fangrui Song via Phabricator via llvm-commits]

MaskRay added a comment.

The GCC implementer did the work for AArch64. They probably did not think of x86 multi-byte NOP. Currently this feature is only used by the Linux kernel on arm64/parisc. I asked whether the x86 implementation should be improved https://gcc.gnu.org/ml/gcc/2020-01/msg00020.html

We don't support M!=0 (-fpatchable-function-entry=N,M). If we do, its interaction with `-falign-functions=32` will be interesting. GCC apparently just simply aligns the first NOP, so the function symbol may be misaligned.


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  https://reviews.llvm.org/D72220/new/

https://reviews.llvm.org/D72220