Remove complex bailouts and fix replacing open_existential_ref

This code was previously turned off for non-ossa and was creating illegal
unchecked_ref_cast with same source and destination.

Author: meg-gupta

lib/SILOptimizer/SILCombiner/SILCombinerApplyVisitors.cpp

@@ -798,30 +798,17 @@ SILCombiner::buildConcreteOpenedExistentialInfoFromSoleConformingType(
   // Prepare the code by adding UncheckedCast instructions that cast opened
   // existentials to concrete types. Set the ConcreteValue of CEI.
   if (auto *OER = dyn_cast<OpenExistentialRefInst>(OAI.OpenedArchetypeValue)) {
-    // If we have an owned open_existential_ref, we only optimize for now if our
-    // open_existential_ref has a single non-debug consuming use that is a
-    // destroy_value.
-    if (OER->getForwardingOwnershipKind() != OwnershipKind::Owned) {
-      // We use OER as the insertion point so that
-      SILBuilderWithScope b(std::next(OER->getIterator()), Builder);
-      auto loc = RegularLocation::getAutoGeneratedLocation();
-      SoleCEI.ConcreteValue =
-          b.createUncheckedRefCast(loc, OER, concreteSILType);
-      return COAI;
-    }
-
-    auto *consumingUse = OER->getSingleConsumingUse();
-    if (!consumingUse || !isa<DestroyValueInst>(consumingUse->getUser())) {
-      return std::nullopt;
-    }
-
-    // We use std::next(OER) as the insertion point so that we can reuse the
-    // destroy_value of consumingUse.
     SILBuilderWithScope b(std::next(OER->getIterator()), Builder);
     auto loc = RegularLocation::getAutoGeneratedLocation();
     auto *uri = b.createUncheckedRefCast(loc, OER, concreteSILType);
     SoleCEI.ConcreteValue = uri;
-    replaceInstUsesWith(*OER, uri);
+    for (auto *use : OER->getUses()) {
+      auto *user = use->getUser();
+      if (user == uri) {
+        continue;
+      }
+      setUseValue(use, uri);
+    }
     return COAI;
   }