[PATCH] D37093: [coroutines] Promote cleanup.dest.slot-like allocas to registers to avoid storing them in the coroutine frame

[Gor Nishanov via Phabricator via llvm-commits]

GorNishanov marked an inline comment as done.
GorNishanov added a comment.

In https://reviews.llvm.org/D37093#857223, @majnemer wrote:

> How are integer allocas special?


clang synthesizes integer allocas for flags and cleanup states to implement dispatching of cleanup code to decide whether something is fully constructed and need destruction and to decide where to go after common cleanup sequence is executed. In https://reviews.llvm.org/owners/package/2/, those synthetic variables are gone. In O0, they stay as variables and coroutine frame building code will put them into the coroutine frame, that may lead to accessing them for cleanup purposes in the initiation function after coroutine frame is already destroyed due to coroutine never suspending.

Potentially this code can be generalized to deal with arbitrarily typed allocas with this pattern, but, I wanted to keep it only for integers since that is the scenario (clang synthesized flags and destination slot variables) I wanted to address.


https://reviews.llvm.org/D37093