implement PUSH0 (#273)

Co-authored-by: Péter Garamvölgyi <th307q@gmail.com>

core/vm/eips.go

@@ -26,6 +26,7 @@ import (
 )
 
 var activators = map[int]func(*JumpTable){
+	3855: enable3855,
 	3529: enable3529,
 	3198: enable3198,
 	2929: enable2929,
@@ -176,3 +177,20 @@ func opBaseFee(pc *uint64, interpreter *EVMInterpreter, scope *ScopeContext) ([]
 	scope.Stack.push(baseFee)
 	return nil, nil
 }
+
+// enable3855 applies EIP-3855 (PUSH0 opcode)
+func enable3855(jt *JumpTable) {
+	// New opcode
+	jt[PUSH0] = &operation{
+		execute:     opPush0,
+		constantGas: GasQuickStep,
+		minStack:    minStack(0, 1),
+		maxStack:    maxStack(0, 1),
+	}
+}
+
+// opPush0 implements the PUSH0 opcode
+func opPush0(pc *uint64, interpreter *EVMInterpreter, scope *ScopeContext) ([]byte, error) {
+	scope.Stack.push(new(uint256.Int))
+	return nil, nil
+}

core/vm/opcodes.go

@@ -120,6 +120,7 @@ const (
 	MSIZE    OpCode = 0x59
 	GAS      OpCode = 0x5a
 	JUMPDEST OpCode = 0x5b
+	PUSH0    OpCode = 0x5f
 )
 
 // 0x60 range - pushes.
@@ -308,6 +309,7 @@ var opCodeToString = map[OpCode]string{
 	MSIZE:    "MSIZE",
 	GAS:      "GAS",
 	JUMPDEST: "JUMPDEST",
+	PUSH0:    "PUSH0",
 
 	// 0x60 range - push.
 	PUSH1:  "PUSH1",
@@ -475,6 +477,7 @@ var stringToOp = map[string]OpCode{
 	"MSIZE":          MSIZE,
 	"GAS":            GAS,
 	"JUMPDEST":       JUMPDEST,
+	"PUSH0":          PUSH0,
 	"PUSH1":          PUSH1,
 	"PUSH2":          PUSH2,
 	"PUSH3":          PUSH3,