[PATCH] D46326: ThinLTO+CFI: short-circuit direct calls to jump table entries

[Vlad Tsyrklevich via Phabricator via llvm-commits]

vlad.tsyrklevich added a comment.

> I get the same result with full LTO and without my changes, ToT from a few days ago. It may be a separate problem.

ToT LTO and ThinLTO builds both work fine for me. Can you post the error you get? I'm not sure how ToT would produce a direct call to a function with a jumptable entry.

> Hmm... This broke some tests, test/Transforms/LowerTypeTests/import-icall.ll to be specific. A direct call to @external, which is a CfiFunctionDecl, is expected to go through a jump table entry. With my change it doesn't.

Presumably it's only expected to because the test just checks the old behavior.

> Playing a bit more with thin and full LTO, it looks like a direct external call to a function with the same type as function pointers used in the program, will go through a jump table entry even in full LTO. Is this by design?

It's the same behavior as done for ThinLTO--it can be replaced with direct calls without impacting the correctness of the CFI checking.


https://reviews.llvm.org/D46326