I have no idea what I am doing.

do_not_duplicate_InitExistentialAddrInst.patch

diff --git a/lib/SIL/IR/SILInstruction.cpp b/lib/SIL/IR/SILInstruction.cpp
index b1e14d28d4..50d6016d68 100644
--- a/lib/SIL/IR/SILInstruction.cpp
+++ b/lib/SIL/IR/SILInstruction.cpp
@@ -1215,6 +1215,9 @@ bool SILInstruction::isTriviallyDuplicatable() const {
 
   // If you add more cases here, you should also update SILLoop:canDuplicate.
 
+  if (isa<InitExistentialAddrInst>(this))
+    return false;
+
   return true;
 }
 
diff --git a/lib/SIL/Utils/LoopInfo.cpp b/lib/SIL/Utils/LoopInfo.cpp
index 72defd29eb..fdb84516da 100644
--- a/lib/SIL/Utils/LoopInfo.cpp
+++ b/lib/SIL/Utils/LoopInfo.cpp
@@ -111,6 +111,9 @@ bool SILLoop::canDuplicate(SILInstruction *I) const {
   if (isa<DynamicMethodBranchInst>(I))
     return false;
 
+  if (isa<InitExistentialAddrInst>(I))
+    return false;
+
   // Some special cases above that aren't considered isTriviallyDuplicatable
   // return true early.
   assert(I->isTriviallyDuplicatable() &&