Implement address(...).code in the IR

libsolidity/codegen/YulUtilFunctions.cpp

@@ -4055,3 +4055,21 @@ string YulUtilFunctions::copyConstructorArgumentsToMemoryFunction(
 		.render();
 	});
 }
+
+string YulUtilFunctions::externalCodeFunction()
+{
+	string functionName = "external_code_at";
+
+	return m_functionCollector.createFunction(functionName, [&]() {
+		return util::Whiskers(R"(
+			function <functionName>(addr) -> mpos {
+				let length := extcodesize(addr)
+				mpos := <allocateArray>(length)
+				extcodecopy(addr, add(mpos, 0x20), 0, length)
+			}
+		)")
+		("functionName", functionName)
+		("allocateArray", allocateMemoryArrayFunction(*TypeProvider::bytesMemory()))
+		.render();
+	});
+}

libsolidity/codegen/YulUtilFunctions.h

@@ -460,6 +460,11 @@ public:
 		std::string const& _creationObjectName
 	);
 
+	/// @returns the name of a function that copies code from a given address to a newly
+	/// allocated byte array in memory.
+	/// Signature: (address) -> mpos
+	std::string externalCodeFunction();
+
 private:
 	/// Special case of conversion functions - handles all array conversions.
 	std::string arrayConversionFunction(ArrayType const& _from, ArrayType const& _to);

libsolidity/codegen/ir/IRGeneratorForStatements.cpp

@@ -1622,6 +1622,12 @@ void IRGeneratorForStatements::endVisit(MemberAccess const& _memberAccess)
 				"balance(" <<
 				expressionAsType(_memberAccess.expression(), *TypeProvider::address()) <<
 				")\n";
+		else if (member == "code")
+			define(_memberAccess) <<
+				m_utils.externalCodeFunction() <<
+				"(" <<
+				expressionAsType(_memberAccess.expression(), *TypeProvider::address()) <<
+				")\n";
 		else if (member == "codehash")
 			define(_memberAccess) <<
 				"extcodehash(" <<