Merge pull request #40739 from nate-chandler/cherrypick/copy-propagation/fixed-assert/release/5.6

[5.6] [ShrinkBorrowScope] Fixed assert.

Author: nate-chandler

lib/SILOptimizer/Utils/ShrinkBorrowScope.cpp

@@ -315,7 +315,13 @@ void ShrinkBorrowScope::findBarriers() {
       // At that time, it was checked that this block (along with all that
       // successor's other predecessors) had a terminator over which the borrow
       // scope could be shrunk.  Shrink it now.
-      assert(tryHoistOverInstruction(block->getTerminator()));
+#ifndef NDEBUG
+      bool hoisted = 
+#endif
+      tryHoistOverInstruction(block->getTerminator());
+#ifndef NDEBUG
+      assert(hoisted);
+#endif
     }
     SILInstruction *barrier = nullptr;
     while ((instruction = getPreviousInstruction(instruction))) {