[PATCH] D75664: [Coroutines] Also check lifetime intrinsic for local variable when build coroutine frame

[JunMa via Phabricator via llvm-commits]

junparser created this revision.
junparser added reviewers: modocache, wenlei, lewissbaker.
Herald added subscribers: llvm-commits, hiraditya, EricWF.
Herald added a project: LLVM.

Currently we move all allocas into the frame when build coroutine frame in CoroSplit pass. However,  this can be relaxed.

Since CoroSplit pass run after Inline pass, we can use lifetime intrinsic to do such analysis: If the scope of lifetime intrinsic is
not across any suspend point,  rather than move the allocas to frame, we can just move them to entry bb of corresponding function. This reduce the frame size.

More importantly, this also avoid data race in multithread environment. Consider one inline function by coroutine: it starts a thread which  access local variables, while after inline the movement of allocs to frame also access them.  cause data race.

TestPlan: check-llvm, cppcoro


https://reviews.llvm.org/D75664

Files:
  llvm/lib/Transforms/Coroutines/CoroFrame.cpp
  llvm/lib/Transforms/Coroutines/CoroSplit.cpp
  llvm/test/Transforms/Coroutines/coro-split-02.ll

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