diff --git a/src/mapleall/maple_be/src/cg/ebo.cpp b/src/mapleall/maple_be/src/cg/ebo.cpp
index 6c14a630afb4eb24398a32b189c89183f467c419..258808e83bf2572f4efa862a5091ba75bfe2a5df 100644
--- a/src/mapleall/maple_be/src/cg/ebo.cpp
+++ b/src/mapleall/maple_be/src/cg/ebo.cpp
@@ -606,7 +606,7 @@ bool Ebo::ForwardPropagateOpnd(Insn &insn, Operand *&opnd, uint32 opndIndex,
   }
   /* Copies to and from the same register are not needed. */
   if (!beforeRegAlloc && Globals::GetInstance()->GetTarget()->IsEffectiveCopy(insn) && (opndIndex == kInsnSecondOpnd) &&
-      RegistersIdentical(*opnd, insn.GetOperand(kInsnFirstOpnd))) {
+      RegistersIdentical(*opnd, insn.GetOperand(kInsnFirstOpnd)) && !LiveOutOfBB(*opnd, *(insn.GetBB()))) {
     if (EBO_DUMP) {
       LogInfo::MapleLogger() << "===replace operand " << opndIndex << " of insn: \n";
       insn.Dump();