Eliminate a compile time warning.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@55878 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/CodeEmitterGen.cpp b/utils/TableGen/CodeEmitterGen.cpp
index 74268a3..e2278ad 100644
--- a/utils/TableGen/CodeEmitterGen.cpp
+++ b/utils/TableGen/CodeEmitterGen.cpp
@@ -220,7 +220,7 @@
   // Emit initial function code
   o << "  const unsigned opcode = MI.getOpcode();\n"
     << "  unsigned Value = InstBits[opcode];\n"
-    << "  unsigned op;\n"
+    << "  unsigned op = 0;\n"
     << "  op = op;  // suppress warning\n"
     << "  switch (opcode) {\n";