[PATCH] D28075: MergeFunctions: Preserve debug info in thunks, under option -mergefunc-preserve-debug-info

[Adrian Prantl via Phabricator via llvm-commits]

aprantl added a comment.

> Call sites of the merged function occurring from within the TU of the merged function's definition will point directly to the shared implementation and call sites of the merged function that are external to the TU of the merged function's definition call the thunk for the merged function (which tail call's the shared implementation passing forward the incoming arguments). This is existing behaviour under -mergefunc and remains unchanged under -mergefunc-preserve-debug-info (except for the tail call part).

Is this the right thing to do, though? I would think that for better debugability users would always prefer the version with the thunk even in the current TU. Then again, subsequent optimization passes would likely inline the thunk and thus potentially undo most of the effect. Have you experimented with this variant? Would the debug info from the thunk survive?


https://reviews.llvm.org/D28075