diff --git a/llvm/lib/Transforms/Coroutines/CoroFrame.cpp b/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
--- a/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
@@ -2576,6 +2576,7 @@
 static void collectFrameAllocas(Function &F, coro::Shape &Shape,
                                 const SuspendCrossingInfo &Checker,
                                 SmallVectorImpl<AllocaInfo> &Allocas) {
+  const DominatorTree DT(F);
   for (Instruction &I : instructions(F)) {
     auto *AI = dyn_cast<AllocaInst>(&I);
     if (!AI)
@@ -2585,7 +2586,6 @@
     if (AI == Shape.SwitchLowering.PromiseAlloca) {
       continue;
     }
-    DominatorTree DT(F);
     // The code that uses lifetime.start intrinsic does not work for functions
     // with loops without exit. Disable it on ABIs we know to generate such
     // code.