[llvm] [Coroutines] Only rematerialize when operands are available after the suspend (PR #209195)

[Weibo He via llvm-commits]

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@@ -316,9 +405,13 @@ void coro::doRematerializations(
   // See if there are materializable instructions across suspend points
   // We record these as the starting point to also identify materializable
   // defs of uses in these operations
+  SmallDenseMap<Value *, bool> AvailMemo;
   for (Instruction &I : instructions(F)) {
     if (!IsMaterializable(I))
       continue;
+    if (!allOperandsAvailableAfterSuspend(I, IsMaterializable, Checker,
+                                          AvailMemo))
+      continue;
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NewSigma wrote:

`allOperandsAvailableAfterSuspend` is expensive. Do we need to traverse operands if the instruction does not cross suspending points?

https://github.com/llvm/llvm-project/pull/209195