[Don't Commit] [DRAFT] Workaround the example in 57861

[ChuanqiXu]

This is not strictly correct.

llvm/lib/Transforms/Coroutines/CoroFrame.cpp

for (const auto &Alias : A.Aliases) {
       auto *AliasPtr = Builder.CreateGEP(Type::getInt8Ty(C), FramePtrRaw,
                                          ConstantInt::get(ITy, Value));
       auto *AliasPtrTyped =
           Builder.CreateBitCast(AliasPtr, Alias.first->getType());
       Alias.first->replaceUsesWithIf(
           AliasPtrTyped, [&](Use &U) { return DT.dominates(CB, U); });
     }
   }
+
+  if (Shape.ABI == coro::ABI::Switch && Shape.SwitchLowering.PromiseAlloca) {
+    AllocaInst *PA = Shape.SwitchLowering.PromiseAlloca;
+    bool HasAccessingPromiseBeforeCB = llvm::any_of(PA->users(), [&](User *U){
+      auto *Inst = cast<Instruction>(U);
+
+      return !Inst->isDebugOrPseudoInst() &&
+             !Inst->isLifetimeStartOrEnd() &&
+             !DT.dominates(CB, Inst);
+    });
+    if (HasAccessingPromiseBeforeCB) {
+      Builder.SetInsertPoint(Shape.getInsertPtAfterFramePtr());
+      auto *G = GetFramePointer(PA);
+      auto *Value = Builder.CreateLoad(PA->getAllocatedType(), PA);
+      Builder.CreateStore(Value, G);
+    }
+  }
 }
 
 // Moves the values in the PHIs in SuccBB that correspong to PredBB into a new
 // PHI in InsertedBB.
 static void movePHIValuesToInsertedBlock(BasicBlock *SuccBB,
                                          BasicBlock *InsertedBB,
                                          BasicBlock *PredBB,
                                          PHINode *UntilPHI = nullptr) {