Start processing function blocks in Subzero.

src/IceInst.cpp

Index: src/IceInst.cpp
diff --git a/src/IceInst.cpp b/src/IceInst.cpp
index 12ca16c4caa0c6fbf14858941294e9cae54722a6..9baa7c80a05b5c9ebf2a2e08cb279d260d86e3fb 100644
--- a/src/IceInst.cpp
+++ b/src/IceInst.cpp
@@ -228,6 +228,12 @@ InstArithmetic::InstArithmetic(Cfg *Func, OpKind Op, Variable *Dest,
   addSource(Source2);
 }
 
+const char *InstArithmetic::getOpName(OpKind Op) {
+  size_t OpIndex = static_cast<size_t>(Op);
+  return OpIndex < InstArithmeticAttributesSize
+      ? InstArithmeticAttributes[OpIndex].DisplayString : "???";
+}
+
 bool InstArithmetic::isCommutative() const {
   return InstArithmeticAttributes[getOp()].IsCommutative;
 }