net.sf.jode.obfuscator.modules
Class ConstantAnalyzer

java.lang.Object
  net.sf.jode.obfuscator.modules.SimpleAnalyzer
      net.sf.jode.obfuscator.modules.ConstantAnalyzer

All Implemented Interfaces:

CodeAnalyzer, CodeTransformer, Opcodes

public class ConstantAnalyzer

extends SimpleAnalyzer

Analyze the code, assuming every field that is not yet written to is constant. This may imply that some code is dead code. While we analyze the Code we remember, which local variable and which stack slot is constant for each instruction and if the instruction is dead. First we assume that every local and every slot is constant for each instruction, and that all instructions are dead code. Now we mark all local variables of the first instruction as not constant and the first instruction as modified. While there is a modified instruction, we pick one and repeat the following algorithm: If the instruction produces a constant result (because it is a ldc instruction, or it combines constant values), we put that instruction on the ConstantListener-Queue of all constant inputs and put the constant result on the ConstantListener-Queue of that instruction.

Author:

Jochen Hoenicke

Field Summary

Fields inherited from interface net.sf.jode.bytecode.Opcodes

constants, newArrayTypes, opc_aaload, opc_aastore, opc_aconst_null, opc_aload, opc_aload_0, opc_aload_1, opc_aload_2, opc_aload_3, opc_anewarray, opc_areturn, opc_arraylength, opc_astore, opc_astore_0, opc_astore_1, opc_astore_2, opc_astore_3, opc_athrow, opc_baload, opc_bastore, opc_bipush, opc_breakpoint, opc_caload, opc_castore, opc_checkcast, opc_d2f, opc_d2i, opc_d2l, opc_dadd, opc_daload, opc_dastore, opc_dcmpg, opc_dcmpl, opc_dconst_0, opc_dconst_1, opc_ddiv, opc_dload, opc_dload_0, opc_dload_1, opc_dload_2, opc_dload_3, opc_dmul, opc_dneg, opc_drem, opc_dreturn, opc_dstore, opc_dstore_0, opc_dstore_1, opc_dstore_2, opc_dstore_3, opc_dsub, opc_dup, opc_dup_x1, opc_dup_x2, opc_dup2, opc_dup2_x1, opc_dup2_x2, opc_f2d, opc_f2i, opc_f2l, opc_fadd, opc_faload, opc_fastore, opc_fcmpg, opc_fcmpl, opc_fconst_0, opc_fconst_1, opc_fconst_2, opc_fdiv, opc_fload, opc_fload_0, opc_fload_1, opc_fload_2, opc_fload_3, opc_fmul, opc_fneg, opc_frem, opc_freturn, opc_fstore, opc_fstore_0, opc_fstore_1, opc_fstore_2, opc_fstore_3, opc_fsub, opc_getfield, opc_getstatic, opc_goto, opc_goto_w, opc_i2b, opc_i2c, opc_i2d, opc_i2f, opc_i2l, opc_i2s, opc_iadd, opc_iaload, opc_iand, opc_iastore, opc_iconst_0, opc_iconst_1, opc_iconst_2, opc_iconst_3, opc_iconst_4, opc_iconst_5, opc_iconst_m1, opc_idiv, opc_if_acmpeq, opc_if_acmpne, opc_if_icmpeq, opc_if_icmpge, opc_if_icmpgt, opc_if_icmple, opc_if_icmplt, opc_if_icmpne, opc_ifeq, opc_ifge, opc_ifgt, opc_ifle, opc_iflt, opc_ifne, opc_ifnonnull, opc_ifnull, opc_iinc, opc_iload, opc_iload_0, opc_iload_1, opc_iload_2, opc_iload_3, opc_impdep1, opc_impdep2, opc_imul, opc_ineg, opc_instanceof, opc_invokeinterface, opc_invokespecial, opc_invokestatic, opc_invokevirtual, opc_ior, opc_irem, opc_ireturn, opc_ishl, opc_ishr, opc_istore, opc_istore_0, opc_istore_1, opc_istore_2, opc_istore_3, opc_isub, opc_iushr, opc_ixor, opc_jsr, opc_jsr_w, opc_l2d, opc_l2f, opc_l2i, opc_ladd, opc_laload, opc_land, opc_lastore, opc_lcmp, opc_lconst_0, opc_lconst_1, opc_ldc, opc_ldc_w, opc_ldc2_w, opc_ldiv, opc_lload, opc_lload_0, opc_lload_1, opc_lload_2, opc_lload_3, opc_lmul, opc_lneg, opc_lookupswitch, opc_lor, opc_lrem, opc_lreturn, opc_lshl, opc_lshr, opc_lstore, opc_lstore_0, opc_lstore_1, opc_lstore_2, opc_lstore_3, opc_lsub, opc_lushr, opc_lxor, opc_monitorenter, opc_monitorexit, opc_multianewarray, opc_new, opc_newarray, opc_nop, opc_pop, opc_pop2, opc_putfield, opc_putstatic, opc_ret, opc_return, opc_saload, opc_sastore, opc_sipush, opc_swap, opc_tableswitch, opc_wide, opc_xxxunusedxxx, opcodeString

Constructor Summary

ConstantAnalyzer()

Method Summary

void	analyzeCode(MethodIdentifier methodIdent, BasicBlocks bb) Reads the opcodes out of the code info and determine its references
void	dumpBlockInfo(java.io.PrintWriter output)
void	fieldNotConstant(FieldIdentifier fi)
static void	replaceWith(java.util.ArrayList newCode, Instruction instr, Instruction replacement)
void	transformCode(BasicBlocks bb)

Methods inherited from class net.sf.jode.obfuscator.modules.SimpleAnalyzer

canonizeReference

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ConstantAnalyzer

public ConstantAnalyzer()

Method Detail

fieldNotConstant

public void fieldNotConstant(FieldIdentifier fi)

dumpBlockInfo

public void dumpBlockInfo(java.io.PrintWriter output)

analyzeCode

public void analyzeCode(MethodIdentifier methodIdent,
                        BasicBlocks bb)

Description copied from class: SimpleAnalyzer

Reads the opcodes out of the code info and determine its references

Specified by:

analyzeCode in interface CodeAnalyzer

Overrides:

analyzeCode in class SimpleAnalyzer

Returns:

an enumeration of the references.

replaceWith

public static void replaceWith(java.util.ArrayList newCode,
                               Instruction instr,
                               Instruction replacement)

transformCode

public void transformCode(BasicBlocks bb)

Specified by:

transformCode in interface CodeTransformer

Overrides:

transformCode in class SimpleAnalyzer