用Java实现JVM第五章《指令集和解释器》

忘是亡心i 2023-01-07 12:22 70阅读 0赞

## 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 ##

jdk 1.8.0  
IntelliJ IDEA Community Edition 2018.3.1 x64

## 配置信息 ##

调试配置  
配置位置：Run/Debug Configurations -> program arguments  
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

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