LoopRotate: Fix avoiding copy_value hoisted to the pre-header

copy_value is marked as having no side effects.
Teach LoopRotate to avoid moving it to the pre header and instead duplicate it while rotating the loop.

lib/SILOptimizer/LoopTransforms/LoopRotate.cpp

@@ -116,6 +116,7 @@ canDuplicateOrMoveToPreheader(SILLoop *loop, SILBasicBlock *preheader,
     if (!inst->mayHaveSideEffects() && !inst->mayReadFromMemory() &&
         !isa<TermInst>(inst) &&
         !isa<AllocationInst>(inst) && /* not marked mayhavesideeffects */
+        !isa<CopyValueInst>(inst) &&
         hasLoopInvariantOperands(inst, loop, invariants)) {
       moves.push_back(inst);
       invariants.insert(inst);