Merge pull request #2490 from ethereum/smallJumpOptimization

Abort early if there is nothing to encode or decode.

libsolidity/codegen/CompilerUtils.cpp

@@ -180,6 +180,9 @@ void CompilerUtils::encodeToMemory(
 		t = t->mobileType()->interfaceType(_encodeAsLibraryTypes)->encodingType();
 	}
 
+	if (_givenTypes.empty())
+		return;
+
 	// Stack during operation:
 	// <v1> <v2> ... <vn> <mem_start> <dyn_head_1> ... <dyn_head_r> <end_of_mem>
 	// The values dyn_head_i are added during the first loop and they point to the head part

libsolidity/codegen/ContractCompiler.cpp

@@ -299,9 +299,12 @@ void ContractCompiler::appendFunctionSelector(ContractDefinition const& _contrac
 
 		// Return tag is used to jump out of the function.
 		eth::AssemblyItem returnTag = m_context.pushNewTag();
-		// Parameter for calldataUnpacker
-		m_context << CompilerUtils::dataStartOffset;
-		appendCalldataUnpacker(functionType->parameterTypes());
+		if (!functionType->parameterTypes().empty())
+		{
+			// Parameter for calldataUnpacker
+			m_context << CompilerUtils::dataStartOffset;
+			appendCalldataUnpacker(functionType->parameterTypes());
+		}
 		m_context.appendJumpTo(m_context.functionEntryLabel(functionType->declaration()));
 		m_context << returnTag;
 		// Return tag and input parameters get consumed.