Added the basefee instruction in YulInterpreter

Author: hrkrshnn

test/tools/yulInterpreter/EVMInstructionInterpreter.cpp

@@ -220,6 +220,8 @@ u256 EVMInstructionInterpreter::eval(
 		return m_state.gasprice;
 	case Instruction::CHAINID:
 		return m_state.chainid;
+	case Instruction::BASEFEE:
+		return m_state.basefee;
 	case Instruction::EXTCODESIZE:
 		return u256(keccak256(h256(arg[0]))) & 0xffffff;
 	case Instruction::EXTCODEHASH:

test/tools/yulInterpreter/Interpreter.h

@@ -90,6 +90,8 @@ struct InterpreterState
 	u256 difficulty = 0x9999999;
 	u256 gaslimit = 4000000;
 	u256 chainid = 0x01;
+	/// The minimum value of basefee: 7 wei.
+	u256 basefee = 0x07;
 	/// Log of changes / effects. Sholud be structured data in the future.
 	std::vector<std::string> trace;
 	/// This is actually an input parameter that more or less limits the runtime.
@@ -227,4 +229,3 @@ class ExpressionEvaluator: public ASTWalker
 };
 
 }
-