用Java实现JVM第五章《指令集和解释器》

2022-05-14 10:29:41

案例介绍

本案例通过java代码实现jvm规范中指令集和解释器，完成后就可以开始执行1到100的加和计算。

Java虚拟机顾名思义，就是一台虚拟的机器，而字节码（bytecode）就是运行在这台虚拟机器上的机器码。我们已经知道，每一个类或者接口都会被Java编译器编译成一个class文件，类或接口的方法信息就放在class文件的method_info结构中。如果方法不是抽象的，也不是本地方法，方法的Java代码就会被编译器编译成字节码（即使方法是空的，编译器也会生成一条return语句），存在method_info结构的Code属性中。

环境准备

1、jdk 1.8.0

2、IntelliJ IDEA Community Edition 2018.3.1 x64

配置信息

1、调试配置

2.1、配置位置：Run/Debug Configurations -> program arguments

2.2、配置内容：-Xjre "C:\Program Files\Java\jdk1.8.0_161\jre" E:\itstack\git\istack-demo\itstack-demo-jvm\itstack-demo-jvm-05\target\test-classes\org\itstack\demo\test\HelloWorld

代码示例

itstack-demo-jvm-05
├── pom.xml
└── src
    └── main
    │    └── java
    │        └── org.itstack.demo.jvm
    │             ├── classfile
    │             │   ├── attributes   {BootstrapMethods/Code/ConstantValue...}
    │             │   ├── constantpool {CONSTANT_TAG_CLASS/CONSTANT_TAG_FIELDREF/CONSTANT_TAG_METHODREF...}
    │             │   ├── ClassFile.java
    │             │   ├── ClassReader.java
    │             │   └── MemberInfo.java
    │             ├── classpath
    │             │   ├── impl
    │             │   │   ├── CompositeEntry.java
    │             │   │   ├── DirEntry.java
    │             │   │   ├── WildcardEntry.java
    │             │   │   └── ZipEntry.java
    │             │   ├── Classpath.java
    │             │   └── Entry.java
    │             ├── classpath
    │             │   ├── base
    │             │   ├── comparisons
    │             │   ├── constants
    │             │   ├── control
    │             │   ├── conversions
    │             │   ├── extended
    │             │   ├── loads
    │             │   ├── math
    │             │   │   ├── add
    │             │   │   ├── and
    │             │   │   ├── div
    │             │   │   ├── iinc
    │             │   │   ├── mul
    │             │   │   ├── neg
    │             │   │   ├── or
    │             │   │   ├── rem
    │             │   │   ├── sh
    │             │   │   ├── sub
    │             │   │   └── xor
    │             │   ├── stack
    │             │   ├── store
    │             │   └── Factory
    │             ├── rtda
    │             │   ├── Frame.java
    │             │   ├── JvmStack.java
    │             │   ├── LocalVars.java
    │             │   ├── OperandStack.java
    │             │   ├── Slot.java
    │             │   └── Thread.java
    │             ├── Cmd.java
    │             ├── Interpret.java
    │             └── Main.java
    └── test
         └── java
             └── org.itstack.demo.test
                 └── HelloWorld.java

Factory.java

public class Factory {
    public static Instruction newInstruction(byte opcode) {
        switch (opcode) {
            case 0x00:
                return new NOP();
            case 0x01:
                return new ACONST_NULL();
            case 0x02:
                return new ICONST_M1();
            case 0x03:
                return new ICONST_0();
            case 0x04:
                return new ICONST_1();
            case 0x05:
                return new ICONST_2();
            case 0x06:
                return new ICONST_3();
            case 0x07:
                return new ICONST_4();
            case 0x08:
                return new ICONST_5();
            case 0x09:
                return new LCONST_0();
            case 0x0a:
                return new LCONST_1();
            case 0x0b:
                return new FCONST_0();
            case 0x0c:
                return new FCONST_1();
            case 0x0d:
                return new FCONST_2();
            case 0x0e:
                return new DCONST_0();
            case 0x0f:
                return new DCONST_1();
            case 0x10:
                return new BIPUSH();
            case 0x11:
                return new SIPUSH();
            // case 0x12:
            //  return &LDC{}
            // case 0x13:
            //  return &LDC_W{}
            // case 0x14:
            //  return &LDC2_W{}
            case 0x15:
                return new ILOAD();
            case 0x16:
                return new LLOAD();
            case 0x17:
                return new FLOAD();
            case 0x18:
                return new DLOAD();
            case 0x19:
                return new ALOAD();
            case 0x1a:
                return new ILOAD_0();
            case 0x1b:
                return new ILOAD_1();
            case 0x1c:
                return new ILOAD_2();
            case 0x1d:
                return new ILOAD_3();
            case 0x1e:
                return new LLOAD_0();
            case 0x1f:
                return new LLOAD_1();
            case 0x20:
                return new LLOAD_2();
            case 0x21:
                return new LLOAD_3();
            case 0x22:
                return new FLOAD_0();
            case 0x23:
                return new FLOAD_1();
            case 0x24:
                return new FLOAD_2();
            case 0x25:
                return new FLOAD_3();
            case 0x26:
                return new DLOAD_0();
            case 0x27:
                return new DLOAD_1();
            case 0x28:
                return new DLOAD_2();
            case 0x29:
                return new DLOAD_3();
            case 0x2a:
                return new ALOAD_0();
            case 0x2b:
                return new ALOAD_1();
            case 0x2c:
                return new ALOAD_2();
            case 0x2d:
                return new ALOAD_3();
            // case 0x2e:
            //  return iaload
            // case 0x2f:
            //  return laload
            // case 0x30:
            //  return faload
            // case 0x31:
            //  return daload
            // case 0x32:
            //  return aaload
            // case 0x33:
            //  return baload
            // case 0x34:
            //  return caload
            // case 0x35:
            //  return saload
            case 0x36:
                return new ISTORE();
            case 0x37:
                return new LSTORE();
            case 0x38:
                return new FSTORE();
            case 0x39:
                return new DSTORE();
            case 0x3a:
                return new ASTORE();
            case 0x3b:
                return new ISTORE_0();
            case 0x3c:
                return new ISTORE_1();
            case 0x3d:
                return new ISTORE_2();
            case 0x3e:
                return new ISTORE_3();
            case 0x3f:
                return new LSTORE_0();
            case 0x40:
                return new LSTORE_1();
            case 0x41:
                return new LSTORE_2();
            case 0x42:
                return new LSTORE_3();
            case 0x43:
                return new FSTORE_0();
            case 0x44:
                return new FSTORE_1();
            case 0x45:
                return new FSTORE_2();
            case 0x46:
                return new FSTORE_3();
            case 0x47:
                return new DSTORE_0();
            case 0x48:
                return new DSTORE_1();
            case 0x49:
                return new DSTORE_2();
            case 0x4a:
                return new DSTORE_3();
            case 0x4b:
                return new ASTORE_0();
            case 0x4c:
                return new ASTORE_1();
            case 0x4d:
                return new ASTORE_2();
            case 0x4e:
                return new ASTORE_3();
            // case 0x4f:
            //  return iastore
            // case 0x50:
            //  return lastore
            // case 0x51:
            //  return fastore
            // case 0x52:
            //  return dastore
            // case 0x53:
            //  return aastore
            // case 0x54:
            //  return bastore
            // case 0x55:
            //  return castore
            // case 0x56:
            //  return sastore
            case 0x57:
                return new POP();
            case 0x58:
                return new POP2();
            case 0x59:
                return new DUP();
            case 0x5a:
                return new DUP_X1();
            case 0x5b:
                return new DUP_X2();
            case 0x5c:
                return new DUP2();
            case 0x5d:
                return new DUP2_X1();
            case 0x5e:
                return new DUP2_X2();
            case 0x5f:
                return new SWAP();
            case 0x60:
                return new IADD();
            case 0x61:
                return new LADD();
            case 0x62:
                return new FADD();
            case 0x63:
                return new DADD();
            case 0x64:
                return new ISUB();
            case 0x65:
                return new LSUB();
            case 0x66:
                return new FSUB();
            case 0x67:
                return new DSUB();
            case 0x68:
                return new IMUL();
            case 0x69:
                return new LMUL();
            case 0x6a:
                return new FMUL();
            case 0x6b:
                return new DMUL();
            case 0x6c:
                return new IDIV();
            case 0x6d:
                return new LDIV();
            case 0x6e:
                return new FDIV();
            case 0x6f:
                return new DDIV();
            case 0x70:
                return new IREM();
            case 0x71:
                return new LREM();
            case 0x72:
                return new FREM();
            case 0x73:
                return new DREM();
            case 0x74:
                return new INEG();
            case 0x75:
                return new LNEG();
            case 0x76:
                return new FNEG();
            case 0x77:
                return new DNEG();
            case 0x78:
                return new ISHL();
            case 0x79:
                return new LSHL();
            case 0x7a:
                return new ISHR();
            case 0x7b:
                return new LSHR();
            case 0x7c:
                return new IUSHR();
            case 0x7d:
                return new LUSHR();
            case 0x7e:
                return new IAND();
            case 0x7f:
                return new LAND();
            case (byte) 0x80:
                return new IOR();
            case (byte) 0x81:
                return new LOR();
            case (byte) 0x82:
                return new IXOR();
            case (byte) 0x83:
                return new LXOR();
            case (byte) 0x84:
                return new IINC();
            case (byte) 0x85:
                return new I2L();
            case (byte) 0x86:
                return new I2F();
            case (byte) 0x87:
                return new I2D();
            case (byte) 0x88:
                return new L2I();
            case (byte) 0x89:
                return new L2F();
            case (byte) 0x8a:
                return new L2D();
            case (byte) 0x8b:
                return new F2I();
            case (byte) 0x8c:
                return new F2L();
            case (byte) 0x8d:
                return new F2D();
            case (byte) 0x8e:
                return new D2I();
            case (byte) 0x8f:
                return new D2L();
            case (byte) 0x90:
                return new D2F();
            case (byte) 0x91:
                return new I2B();
            case (byte) 0x92:
                return new I2C();
            case (byte) 0x93:
                return new I2S();
            case (byte) 0x94:
                return new LCMP();
            case (byte) 0x95:
                return new FCMPL();
            case (byte) 0x96:
                return new FCMPG();
            case (byte) 0x97:
                return new DCMPL();
            case (byte) 0x98:
                return new DCMPG();
            case (byte) 0x99:
                return new IFEQ();
            case (byte) 0x9a:
                return new IFNE();
            case (byte) 0x9b:
                return new IFLT();
            case (byte) 0x9c:
                return new IFGE();
            case (byte) 0x9d:
                return new IFGT();
            case (byte) 0x9e:
                return new IFLE();
            case (byte) 0x9f:
                return new IF_ICMPEQ();
            case (byte) 0xa0:
                return new IF_ICMPNE();
            case (byte) 0xa1:
                return new IF_ICMPLT();
            case (byte) 0xa2:
                return new IF_ICMPGE();
            case (byte) 0xa3:
                return new IF_ICMPGT();
            case (byte) 0xa4:
                return new IF_ICMPLE();
            case (byte) 0xa5:
                return new IF_ACMPEQ();
            case (byte) 0xa6:
                return new IF_ACMPNE();
            case (byte) 0xa7:
                return new GOTO();
            // case 0xa8:
            //  return &JSR{}
            // case 0xa9:
            //  return &RET{}
            case (byte) 0xaa:
                return new TABLE_SWITCH();
            case (byte) 0xab:
                return new LOOKUP_SWITCH();
            // case 0xac:
            //  return ireturn
            // case 0xad:
            //  return lreturn
            // case 0xae:
            //  return freturn
            // case 0xaf:
            //  return dreturn
            // case 0xb0:
            //  return areturn
            // case 0xb1:
            //  return _return
            //  case 0xb2:
            //      return &GET_STATIC{}
            // case 0xb3:
            //  return &PUT_STATIC{}
            // case 0xb4:
            //  return &GET_FIELD{}
            // case 0xb5:
            //  return &PUT_FIELD{}
            //  case 0xb6:
            //      return &INVOKE_VIRTUAL{}
            // case 0xb7:
            //  return &INVOKE_SPECIAL{}
            // case 0xb8:
            //  return &INVOKE_STATIC{}
            // case 0xb9:
            //  return &INVOKE_INTERFACE{}
            // case 0xba:
            //  return &INVOKE_DYNAMIC{}
            // case 0xbb:
            //  return &NEW{}
            // case 0xbc:
            //  return &NEW_ARRAY{}
            // case 0xbd:
            //  return &ANEW_ARRAY{}
            // case 0xbe:
            //  return arraylength
            // case 0xbf:
            //  return athrow
            // case 0xc0:
            //  return &CHECK_CAST{}
            // case 0xc1:
            //  return &INSTANCE_OF{}
            // case 0xc2:
            //  return monitorenter
            // case 0xc3:
            //  return monitorexit
            case (byte) 0xc4:
                return new WIDE();
            // case 0xc5:
            //  return &MULTI_ANEW_ARRAY{}
            case (byte) 0xc6:
                return new IFNULL();
            case (byte) 0xc7:
                return new IFNONNULL();
            case (byte) 0xc8:
                return new GOTO_W();
            // case 0xc9:
            //  return &JSR_W{}
            // case 0xca: breakpoint
            // case 0xfe: impdep1
            // case 0xff: impdep2
            default:
                return null;
        }
    }
}

Interpret.java

//指令集解释器
class Interpret {
    Interpret(MemberInfo m) {
        CodeAttribute codeAttr = m.codeAttribute();
        int maxLocals = codeAttr.maxLocals();
        int maxStack = codeAttr.maxStack();
        byte[] byteCode = codeAttr.data();
        Thread thread = new Thread();
        Frame frame = thread.newFrame(maxLocals, maxStack);
        thread.pushFrame(frame);
        loop(thread, byteCode);
    }
    private void loop(Thread thread, byte[] byteCode) {
        Frame frame = thread.popFrame();
        BytecodeReader reader = new BytecodeReader();
        while (true) {
            //循环
            int pc = frame.nextPC();
            thread.setPC(pc);
            //decode
            reader.reset(byteCode, pc);
            byte opcode = reader.readByte();
            Instruction inst = Factory.newInstruction(opcode);
            if (null == inst) {
                System.out.println("寄存器(指令)尚未实现 " + byteToHexString(new byte[]{opcode}));
                break;
            }
            inst.fetchOperands(reader);
            frame.setNextPC(reader.pc());
            System.out.println("寄存器(指令)：" + byteToHexString(new byte[]{opcode}) + " -> " + inst.getClass().getSimpleName() + " => 局部变量表：" + JSON.toJSONString(frame.operandStack().getSlots()) + " 操作数栈：" + JSON.toJSONString(frame.operandStack().getSlots()));            //exec
            inst.execute(frame);
        }
    }
    private static String byteToHexString(byte[] codes) {
        StringBuilder sb = new StringBuilder();
        sb.append("0x");
        for (byte b : codes) {
            int value = b & 0xFF;
            String strHex = Integer.toHexString(value);
            if (strHex.length() < 2) {
                strHex = "0" + strHex;
            }
            sb.append(strHex);
        }
        return sb.toString();
    }
}

HelloWorld.java

package org.itstack.demo.test;
public class HelloWorld {
    
    public static void main(String[] args) {
        int sum = 0;
        for (int i = 1; i <= 100; i++) {
            sum += i;
        }
        System.out.println(sum);
    }
    
}

测试结果

{此时还不能输出结果，但是在操作数据栈中已经可以看到结果：5050}

"C:\Program Files\Java\jdk1.8.0_161\bin\java.exe" "-javaagent:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2018.3.1\lib\idea_rt.jar=61887:D:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2018.3.1\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_161\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_161\jre\lib\rt.jar;E:\itstack\git\istack-demo\itstack-demo-jvm\itstack-demo-jvm-05\target\classes;D:\Program Files (x86)\apache-maven-2.2.1\repository\com\beust\jcommander\1.72\jcommander-1.72.jar;D:\Program Files (x86)\apache-maven-2.2.1\repository\org\projectlombok\lombok\1.18.0\lombok-1.18.0.jar;D:\Program Files (x86)\apache-maven-2.2.1\repository\com\alibaba\fastjson\1.2.40\fastjson-1.2.40.jar" org.itstack.demo.jvm.Main -Xjre "C:\Program Files\Java\jdk1.8.0_161\jre" E:\itstack\git\istack-demo\itstack-demo-jvm\itstack-demo-jvm-05\target\test-classes\org\itstack\demo\test\HelloWorld
classpath:org.itstack.demo.jvm.classpath.Classpath@4bf558aa class:E:\itstack\git\istack-demo\itstack-demo-jvm\itstack-demo-jvm-05\target\test-classes\org\itstack\demo\test\HelloWorld args:null
寄存器(指令)：0x03 -> ICONST_0 => 局部变量表：[{"num":0},{"num":0}] 操作数栈：[{"num":0},{"num":0}]
寄存器(指令)：0x3c -> ISTORE_1 => 局部变量表：[{"num":0},{"num":0}] 操作数栈：[{"num":0},{"num":0}]
寄存器(指令)：0x04 -> ICONST_1 => 局部变量表：[{"num":0},{"num":0}] 操作数栈：[{"num":0},{"num":0}]
寄存器(指令)：0x3d -> ISTORE_2 => 局部变量表：[{"num":1},{"num":0}] 操作数栈：[{"num":1},{"num":0}]
寄存器(指令)：0x1c -> ILOAD_2 => 局部变量表：[{"num":1},{"num":0}] 操作数栈：[{"num":1},{"num":0}]
寄存器(指令)：0x10 -> BIPUSH => 局部变量表：[{"num":1},{"num":0}] 操作数栈：[{"num":1},{"num":0}]
寄存器(指令)：0xa3 -> IF_ICMPGT => 局部变量表：[{"num":1},{"num":100}] 操作数栈：[{"num":1},{"num":100}]
寄存器(指令)：0x1b -> ILOAD_1 => 局部变量表：[{"num":1},{"num":100}] 操作数栈：[{"num":1},{"num":100}]
寄存器(指令)：0x1c -> ILOAD_2 => 局部变量表：[{"num":0},{"num":100}] 操作数栈：[{"num":0},{"num":100}]
... ...
寄存器(指令)：0x60 -> IADD => 局部变量表：[{"num":4950},{"num":100}] 操作数栈：[{"num":4950},{"num":100}]
寄存器(指令)：0x3c -> ISTORE_1 => 局部变量表：[{"num":5050},{"num":100}] 操作数栈：[{"num":5050},{"num":100}]
寄存器(指令)：0x84 -> IINC => 局部变量表：[{"num":5050},{"num":100}] 操作数栈：[{"num":5050},{"num":100}]
寄存器(指令)：0xa7 -> GOTO => 局部变量表：[{"num":5050},{"num":100}] 操作数栈：[{"num":5050},{"num":100}]
寄存器(指令)：0x1c -> ILOAD_2 => 局部变量表：[{"num":5050},{"num":100}] 操作数栈：[{"num":5050},{"num":100}]
寄存器(指令)：0x10 -> BIPUSH => 局部变量表：[{"num":101},{"num":100}] 操作数栈：[{"num":101},{"num":100}]
寄存器(指令)：0xa3 -> IF_ICMPGT => 局部变量表：[{"num":101},{"num":100}] 操作数栈：[{"num":101},{"num":100}]
寄存器(指令)尚未实现 0xb2
Process finished with exit code 0

码农公寓

案例介绍

环境准备

配置信息

代码示例

测试结果

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