Fix Subzero binary instruction to allow optional flags argument.

src/PNaClTranslator.cpp

Index: src/PNaClTranslator.cpp
diff --git a/src/PNaClTranslator.cpp b/src/PNaClTranslator.cpp
index caa0c57c6a05052f1d2926d63039102baba66301..27260c39766cec45d3265df5ba9407ceea7cde90 100644
--- a/src/PNaClTranslator.cpp
+++ b/src/PNaClTranslator.cpp
@@ -2198,8 +2198,12 @@ void FunctionParser::ProcessRecord() {
     return;
   }
   case naclbitc::FUNC_CODE_INST_BINOP: {
-    // BINOP: [opval, opval, opcode]
-    if (!isValidRecordSize(3, "binop"))
+    // Note: Old bitcode files may have an additional 'flags' operand, which is
+    // ignored.
+
+    // BINOP: [opval, opval, opcode, [flags]]
+
+    if (!isValidRecordSizeInRange(3, 4, "binop"))
       return;
     Ice::Operand *Op1 = getRelativeOperand(Values[0], BaseIndex);
     Ice::Operand *Op2 = getRelativeOperand(Values[1], BaseIndex);