Package javassist.bytecode.analysis
Class Analyzer
java.lang.Object
javassist.bytecode.analysis.Analyzer
- All Implemented Interfaces:
Opcode
A data-flow analyzer that determines the type state of the stack and local
variable table at every reachable instruction in a method. During analysis,
bytecode verification is performed in a similar manner to that described
in the JVM specification.
Example:
// Method to analyze public Object doSomething(int x) { Number n; if (x < 5) { n = new Double(0); } else { n = new Long(0); } return n; } // Which compiles to: // 0: iload_1 // 1: iconst_5 // 2: if_icmpge 17 // 5: new #18; //class java/lang/Double // 8: dup // 9: dconst_0 // 10: invokespecial #44; //Method java/lang/Double."<init>":(D)V // 13: astore_2 // 14: goto 26 // 17: new #16; //class java/lang/Long // 20: dup // 21: lconst_1 // 22: invokespecial #47; //Method java/lang/Long."<init>":(J)V // 25: astore_2 // 26: aload_2 // 27: areturn public void analyzeIt(CtClass clazz, MethodInfo method) { Analyzer analyzer = new Analyzer(); Frame[] frames = analyzer.analyze(clazz, method); frames[0].getLocal(0).getCtClass(); // returns clazz; frames[0].getLocal(1).getCtClass(); // returns java.lang.String frames[1].peek(); // returns Type.INTEGER frames[27].peek().getCtClass(); // returns java.lang.Number }
- See Also:
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Nested Class Summary
Nested Classes -
Field Summary
FieldsModifier and TypeFieldDescriptionprivate CtClass
private Analyzer.ExceptionInfo[]
private Frame[]
private final SubroutineScanner
private Subroutine[]
Fields inherited from interface javassist.bytecode.Opcode
AALOAD, AASTORE, ACONST_NULL, ALOAD, ALOAD_0, ALOAD_1, ALOAD_2, ALOAD_3, ANEWARRAY, ARETURN, ARRAYLENGTH, ASTORE, ASTORE_0, ASTORE_1, ASTORE_2, ASTORE_3, ATHROW, BALOAD, BASTORE, BIPUSH, CALOAD, CASTORE, CHECKCAST, D2F, D2I, D2L, DADD, DALOAD, DASTORE, DCMPG, DCMPL, DCONST_0, DCONST_1, DDIV, DLOAD, DLOAD_0, DLOAD_1, DLOAD_2, DLOAD_3, DMUL, DNEG, DREM, DRETURN, DSTORE, DSTORE_0, DSTORE_1, DSTORE_2, DSTORE_3, DSUB, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, F2D, F2I, F2L, FADD, FALOAD, FASTORE, FCMPG, FCMPL, FCONST_0, FCONST_1, FCONST_2, FDIV, FLOAD, FLOAD_0, FLOAD_1, FLOAD_2, FLOAD_3, FMUL, FNEG, FREM, FRETURN, FSTORE, FSTORE_0, FSTORE_1, FSTORE_2, FSTORE_3, FSUB, GETFIELD, GETSTATIC, GOTO, GOTO_W, I2B, I2C, I2D, I2F, I2L, I2S, IADD, IALOAD, IAND, IASTORE, ICONST_0, ICONST_1, ICONST_2, ICONST_3, ICONST_4, ICONST_5, ICONST_M1, IDIV, IF_ACMPEQ, IF_ACMPNE, IF_ICMPEQ, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ICMPLT, IF_ICMPNE, IFEQ, IFGE, IFGT, IFLE, IFLT, IFNE, IFNONNULL, IFNULL, IINC, ILOAD, ILOAD_0, ILOAD_1, ILOAD_2, ILOAD_3, IMUL, INEG, INSTANCEOF, INVOKEDYNAMIC, INVOKEINTERFACE, INVOKESPECIAL, INVOKESTATIC, INVOKEVIRTUAL, IOR, IREM, IRETURN, ISHL, ISHR, ISTORE, ISTORE_0, ISTORE_1, ISTORE_2, ISTORE_3, ISUB, IUSHR, IXOR, JSR, JSR_W, L2D, L2F, L2I, LADD, LALOAD, LAND, LASTORE, LCMP, LCONST_0, LCONST_1, LDC, LDC_W, LDC2_W, LDIV, LLOAD, LLOAD_0, LLOAD_1, LLOAD_2, LLOAD_3, LMUL, LNEG, LOOKUPSWITCH, LOR, LREM, LRETURN, LSHL, LSHR, LSTORE, LSTORE_0, LSTORE_1, LSTORE_2, LSTORE_3, LSUB, LUSHR, LXOR, MONITORENTER, MONITOREXIT, MULTIANEWARRAY, NEW, NEWARRAY, NOP, POP, POP2, PUTFIELD, PUTSTATIC, RET, RETURN, SALOAD, SASTORE, SIPUSH, STACK_GROW, SWAP, T_BOOLEAN, T_BYTE, T_CHAR, T_DOUBLE, T_FLOAT, T_INT, T_LONG, T_SHORT, TABLESWITCH, WIDE
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionFrame[]
analyze
(CtClass clazz, MethodInfo method) Performs data-flow analysis on a method and returns an array, indexed by instruction position, containing the starting frame state of all reachable instructions.Frame[]
Performs data-flow analysis on a method and returns an array, indexed by instruction position, containing the starting frame state of all reachable instructions.private void
analyzeNextEntry
(MethodInfo method, CodeIterator iter, IntQueue queue, Executor executor) private Analyzer.ExceptionInfo[]
buildExceptionInfo
(MethodInfo method) private Frame
firstFrame
(MethodInfo method, int maxLocals, int maxStack) private int
getNext
(CodeIterator iter, int of, int restore) private int
lookAhead
(CodeIterator iter, int pos) private void
private void
mergeExceptionHandlers
(IntQueue queue, MethodInfo method, int pos, Frame frame) private void
mergeJsr
(IntQueue queue, Frame frame, Subroutine sub, int pos, int next) private void
mergeLookupSwitch
(IntQueue queue, int pos, CodeIterator iter, Frame frame) private void
mergeRet
(IntQueue queue, CodeIterator iter, int pos, Frame frame, Subroutine subroutine) private void
mergeTableSwitch
(IntQueue queue, int pos, CodeIterator iter, Frame frame) private Type
zeroExtend
(Type type)
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Field Details
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scanner
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clazz
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exceptions
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frames
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subroutines
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Constructor Details
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Analyzer
public Analyzer()
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Method Details
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analyze
Performs data-flow analysis on a method and returns an array, indexed by instruction position, containing the starting frame state of all reachable instructions. Non-reachable code, and illegal code offsets are represented as a null in the frame state array. This can be used to detect dead code. If the method does not contain code (it is either native or abstract), null is returned.- Parameters:
clazz
- the declaring class of the methodmethod
- the method to analyze- Returns:
- an array, indexed by instruction position, of the starting frame state, or null if this method doesn't have code
- Throws:
BadBytecode
- if the bytecode does not comply with the JVM specification
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analyze
Performs data-flow analysis on a method and returns an array, indexed by instruction position, containing the starting frame state of all reachable instructions. Non-reachable code, and illegal code offsets are represented as a null in the frame state array. This can be used to detect dead code. If the method does not contain code (it is either native or abstract), null is returned.- Parameters:
method
- the method to analyze- Returns:
- an array, indexed by instruction position, of the starting frame state, or null if this method doesn't have code
- Throws:
BadBytecode
- if the bytecode does not comply with the JVM specification
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analyzeNextEntry
private void analyzeNextEntry(MethodInfo method, CodeIterator iter, IntQueue queue, Executor executor) throws BadBytecode - Throws:
BadBytecode
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buildExceptionInfo
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firstFrame
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getNext
- Throws:
BadBytecode
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lookAhead
- Throws:
BadBytecode
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merge
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mergeExceptionHandlers
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mergeJsr
private void mergeJsr(IntQueue queue, Frame frame, Subroutine sub, int pos, int next) throws BadBytecode - Throws:
BadBytecode
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mergeLookupSwitch
private void mergeLookupSwitch(IntQueue queue, int pos, CodeIterator iter, Frame frame) throws BadBytecode - Throws:
BadBytecode
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mergeRet
private void mergeRet(IntQueue queue, CodeIterator iter, int pos, Frame frame, Subroutine subroutine) throws BadBytecode - Throws:
BadBytecode
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mergeTableSwitch
private void mergeTableSwitch(IntQueue queue, int pos, CodeIterator iter, Frame frame) throws BadBytecode - Throws:
BadBytecode
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zeroExtend
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