Fix operand lookup in functions to check if local index out of range.

src/PNaClTranslator.cpp

Index: src/PNaClTranslator.cpp
diff --git a/src/PNaClTranslator.cpp b/src/PNaClTranslator.cpp
index d8d1860f1ef760bf1ac5bda1b21f5cb964562d9e..d3c71fd4091cb737d4bbe45f4347fac86b0cfba6 100644
--- a/src/PNaClTranslator.cpp
+++ b/src/PNaClTranslator.cpp
@@ -1283,16 +1283,14 @@ public:
     if (Index < CachedNumGlobalValueIDs) {
       return Context->getGlobalConstantByID(Index);
     }
+    if (isIRGenerationDisabled())
+      return nullptr;
     NaClBcIndexSize_t LocalIndex = Index - CachedNumGlobalValueIDs;
+    if (LocalIndex >= LocalOperands.size())
+      reportGetOperandUndefined(Index);
     Ice::Operand *Op = LocalOperands[LocalIndex];
-    if (Op == nullptr) {
-      if (isIRGenerationDisabled())
-        return nullptr;
-      std::string Buffer;
-      raw_string_ostream StrBuf(Buffer);
-      StrBuf << "Value index " << Index << " not defined!";
-      Fatal(StrBuf.str());
-    }
+    if (Op == nullptr)
+      reportGetOperandUndefined(Index);
     return Op;
   }
 
@@ -1981,6 +1979,13 @@ private:
     Ice::Variable *Var = getNextInstVar(Ty);
     CurrentNode->appendInst(Ice::InstAssign::create(Func.get(), Var, Var));
   }
+
+  Ice::Operand *reportGetOperandUndefined(NaClBcIndexSize_t Index) {
+    std::string Buffer;
+    raw_string_ostream StrBuf(Buffer);
+    StrBuf << "Value index " << Index << " not defined!";
+    Fatal(StrBuf.str());
+  }
 };
 
 void FunctionParser::ExitBlock() {