[PATCH] D72215: [AArch64] Add function attribute "patchable-function-entry" to add NOPs at function entry

Sat Jan 11 09:06:23 PST 2020

reames added a comment.

In D72215#1809133 <https://reviews.llvm.org/D72215#1809133>, @MaskRay wrote:

> @reames Is D19046 <https://reviews.llvm.org/D19046> the LLVM function attribute "patchable-function" and the target opcode PATCHABLE_OP used by any projects? Sanjoy said you may know.

Sorry, for the slow response.

Yes, the existing attribute is in place.  The difference between the two based on a quick read is that patchable-function expects a destructive patch (i.e. replacing an existing instruction) whereas the new code expects a non-destructive (i.e. replace nops) patch.  There could be some more communing in the implementation and naming, but I have no problem with supporting both.

And yes, "patchable-function" is in use.  We use it for target redirection when replacing a piece of compiled code with another.

Repository:
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  https://reviews.llvm.org/D72215/new/

https://reviews.llvm.org/D72215