[clang] [llvm] [coroutine] Implement llvm.coro.await.suspend intrinsic (PR #79712)

[via llvm-commits]

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@@ -1575,6 +1650,36 @@ static bool hasCallsBetween(Instruction *Save, Instruction *ResumeOrDestroy) {
   return false;
 }
 
+// Check if await-suspend helper is "simple".
+// The conditions are:
+// 1. The return result is exactly coroutine frame parameter, passed to helper
+// 2. There are no calls between any of the returns and helper entry that could
+// resume or destroy it
+// FIXME: perform more sophisiticated analysis?
+static bool isSimpleHelper(CoroAwaitSuspendInst *AWS) {
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fpasserby wrote:

This method was added so that previously available optimization is not lost after this change. If you really feel this is too minor, I will remove it.

https://github.com/llvm/llvm-project/pull/79712