[PATCH] D94388: [Coroutine][DebugInfo] Enhance the ability of coroutine to debug parameters under O2

Thu Jan 14 17:54:33 PST 2021

junparser added a comment.

In D94388#2494294 <https://reviews.llvm.org/D94388#2494294>, @aprantl wrote:

> Do we understand *why* the frontend is emitting the variables twice? If that just a bug in the clang frontend (which would be my first guess) then we should aim at fixing the frontend instead. If the frontend is trying to do something different, I would love to understand what that is.

Hi @aprantl, 
According to the standard, coroutine needs to copy parameters (calling constructor) passed to the coroutine function by the original caller into the coroutine frame. So in frontend, we fake local variables for this behavior, that why we see two variables in debuginfo.

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https://reviews.llvm.org/D94388