Menu
I have a (obfuscated) METHOD that I printed using ASM and the output was as follows:
METHOD: m(ZB)Lcc;
--------------------------------------
L0:
{
ALOAD_0
GETFIELD d/x I
LDC 2036719157
IMUL
ISTORE
GOTO L1
}
L2:
{
ALOAD_6
ICONST_0
LDC -373364649
ALOAD_0
GETFIELD d/at I
IMUL
ICONST_0
INVOKEVIRTUAL cc/y(III)V
GOTO L3
}
L4:
{
ACONST_NULL
ARETURN
}
L5:
{
ILOAD_1
IFEQ L6
LDC -723220973
ALOAD_0
GETFIELD d/an I
IMUL
ISTORE
LDC 1671960653
ALOAD_0
GETFIELD d/ad I
IMUL
ISTORE
GOTO L7
}
L8:
{
LDC 1955946639
ALOAD_0
GETFIELD d/au I
IMUL
IFEQ L9
ILOAD_2
ICONST_1
IF_ICMPEQ L10
NEW
DUP
INVOKESPECIAL java/lang/IllegalStateException/<init>()V
ATHROW
}
L11:
{
IINC
GOTO L12
}
L7:
{
LDC 894092883
ALOAD_0
GETFIELD d/ac I
IMUL
ISTORE
GOTO L6
}
L13:
{
GETSTATIC d/b Lem;
ILOAD_3
ICONST_0
INVOKESTATIC cc/l(Lem;II)Lcc;
ASTORE
ILOAD_4
ICONST_M1
IF_ICMPEQ L14
GETSTATIC d/b Lem;
ILOAD_4
ICONST_0
INVOKESTATIC cc/l(Lem;II)Lcc;
ASTORE
GOTO L15
}
L16:
{
ICONST_2
ANEWARRAY
DUP
ICONST_0
ALOAD_6
AASTORE
DUP
ICONST_1
ALOAD_7
AASTORE
ASTORE
GOTO L17
}
L18:
{
GETSTATIC d/b Lem;
ILOAD_5
ICONST_0
INVOKESTATIC cc/l(Lem;II)Lcc;
ASTORE
ICONST_3
ANEWARRAY
DUP
ICONST_0
ALOAD_6
AASTORE
DUP
ICONST_1
ALOAD_7
AASTORE
DUP
ICONST_2
ALOAD_8
AASTORE
ASTORE
NEW
DUP
ALOAD_9
ICONST_3
INVOKESPECIAL cc/<init>([Lcc;I)V
ASTORE
GOTO L14
}
L19:
{
ALOAD_6
ARETURN
}
L17:
{
NEW
DUP
ALOAD_8
ICONST_2
INVOKESPECIAL cc/<init>([Lcc;I)V
ASTORE
}
L14:
{
ILOAD_1
IFNE L9
ILOAD_2
ICONST_1
IF_ICMPEQ L8
NEW
DUP
INVOKESPECIAL java/lang/IllegalStateException/<init>()V
ATHROW
}
L15:
{
ILOAD_5
ICONST_M1
IF_ICMPEQ L16
ILOAD_2
ICONST_1
IF_ICMPEQ L18
NEW
DUP
INVOKESPECIAL java/lang/IllegalStateException/<init>()V
ATHROW
}
L20:
{
LDC 1642271889
ALOAD_0
GETFIELD d/ay I
IMUL
ISTORE
GOTO L5
}
L9:
{
ILOAD_1
IFEQ L3
ILOAD_2
ICONST_1
IF_ICMPEQ L21
NEW
DUP
INVOKESPECIAL java/lang/IllegalStateException/<init>()V
ATHROW
}
L21:
{
ICONST_0
LDC -373364649
ALOAD_0
GETFIELD d/at I
IMUL
IF_ICMPEQ L3
ILOAD_2
ICONST_1
IF_ICMPEQ L2
NEW
DUP
INVOKESPECIAL java/lang/IllegalStateException/<init>()V
ATHROW
}
L22:
{
ICONST_0
ISTORE
GOTO L23
}
L3:
{
ALOAD_0
GETFIELD d/c [S
IFNULL L24
ILOAD_2
ICONST_1
IF_ICMPEQ L25
NEW
DUP
INVOKESPECIAL java/lang/IllegalStateException/<init>()V
ATHROW
}
L25:
{
ICONST_0
ISTORE
GOTO L12
}
L24:
{
ALOAD_0
GETFIELD d/a [S
IFNULL L19
ILOAD_2
ICONST_1
IF_ICMPEQ L22
NEW
DUP
INVOKESPECIAL java/lang/IllegalStateException/<init>()V
ATHROW
}
L26:
{
ALOAD_6
ALOAD_0
GETFIELD d/c [S
ILOAD_7
SALOAD
ALOAD_0
GETFIELD d/m [S
ILOAD_7
SALOAD
INVOKEVIRTUAL cc/v(SS)V
GOTO L11
}
L12:
{
ILOAD_7
ALOAD_0
GETFIELD d/c [S
ARRAYLENGTH
IF_ICMPGE L24
GOTO L26
}
L1:
{
ALOAD_0
GETFIELD d/ar I
LDC 608958183
IMUL
ISTORE
GOTO L20
}
L10:
{
ALOAD_6
ICONST_0
LDC 1955946639
ALOAD_0
GETFIELD d/au I
IMUL
ICONST_0
INVOKEVIRTUAL cc/y(III)V
GOTO L9
}
L23:
{
ILOAD_7
ALOAD_0
GETFIELD d/a [S
ARRAYLENGTH
IF_ICMPGE L19
ILOAD_2
ICONST_1
IF_ICMPEQ L27
NEW
DUP
INVOKESPECIAL java/lang/IllegalStateException/<init>()V
ATHROW
}
L27:
{
ALOAD_6
ALOAD_0
GETFIELD d/a [S
ILOAD_7
SALOAD
ALOAD_0
GETFIELD d/e [S
ILOAD_7
SALOAD
INVOKEVIRTUAL cc/s(SS)V
IINC
GOTO L23
}
L6:
{
ILOAD_3
ICONST_M1
IF_ICMPNE L13
GOTO L4
}
L28:
{
NEW
DUP
INVOKESPECIAL java/lang/StringBuilder/<init>()V
LDC "af.m("
INVOKEVIRTUAL java/lang/StringBuilder/append(Ljava/lang/String;)Ljava/lang/StringBuilder;
LDC 41
INVOKEVIRTUAL java/lang/StringBuilder/append(C)Ljava/lang/StringBuilder;
INVOKEVIRTUAL java/lang/StringBuilder/toString()Ljava/lang/String;
INVOKESTATIC b/b(Ljava/lang/Throwable;Ljava/lang/String;)Lcd;
ATHROW
}
I want to REMOVE all the exceptions. For example (I want to remove):
ILOAD_2
ICONST_1
IF_ICMPEQ L27
NEW
DUP
INVOKESPECIAL java/lang/IllegalStateException/<init>()V
ATHROW
which is translated as: if (var2 != 1) {throw new IllegalStateException();}
I don't plan on running the class but I do plan on it being properly assembled. Meaning that if I remove the exception, there won't be any bytecode errors when using the CheckClassAdapter. I don't need the code to actually work.
I tried the following which I used to remove the exceptions:
private void findException(MethodNode method) {
int i = findExceptionIndex(method); //returns the first occurrence of the above pattern.
while (i != -1) {
for (int j = i; j < i + 7; ++j) { //length of if statement + exception instructions.
if (method.instructions.get(j) instanceof MethodInsnNode) {
//if it really is an exception
if (((MethodInsnNode) method.instructions.get(j)).owner.contains("Exception")) {
for (int k = i + 6; k != i - 1; --k) {
System.out.println("Removing: " + Printer.OPCODES[method.instructions.get(k).getOpcode()]);
method.instructions.remove(method.instructions.get(k));
}
return; //I only want to try to remove one first (before trying to remove all)
}
}
}
i = findNextExceptionIndex(method, i);
}
}
and it prints (successfully removed the first exception that has the following Opcodes):
Removing: ATHROW
Removing: INVOKESPECIAL
Removing: DUP
Removing: NEW
Removing: IF_ICMPEQ
Removing: ICONST_1
Removing: ILOAD
However, I get a HUGE exception when I try to save the class:
jdk.internal.org.objectweb.asm.tree.analysis.AnalyzerException: Error at instruction 41: Expected I, but found .
at jdk.internal.org.objectweb.asm.tree.analysis.Analyzer.analyze(Analyzer.java:323)
at jdk.internal.org.objectweb.asm.util.CheckMethodAdapter$1.visitEnd(CheckMethodAdapter.java:479)
at jdk.internal.org.objectweb.asm.MethodVisitor.visitEnd(MethodVisitor.java:906)
at jdk.internal.org.objectweb.asm.util.CheckMethodAdapter.visitEnd(CheckMethodAdapter.java:1057)
at jdk.internal.org.objectweb.asm.tree.MethodNode.accept(MethodNode.java:866)
at jdk.internal.org.objectweb.asm.tree.MethodNode.accept(MethodNode.java:755)
at jdk.internal.org.objectweb.asm.tree.ClassNode.accept(ClassNode.java:441)
at com.other.JarParser.saveClass(JarParser.java:81)
Caused by: jdk.internal.org.objectweb.asm.tree.analysis.AnalyzerException: Expected I, but found .
at jdk.internal.org.objectweb.asm.tree.analysis.BasicVerifier.unaryOperation(BasicVerifier.java:211)
at jdk.internal.org.objectweb.asm.tree.analysis.BasicVerifier.unaryOperation(BasicVerifier.java:76)
at jdk.internal.org.objectweb.asm.tree.analysis.Frame.execute(Frame.java:546)
at jdk.internal.org.objectweb.asm.tree.analysis.Analyzer.analyze(Analyzer.java:228)
... 14 more
Exception in thread "main" java.lang.RuntimeException: Error at instruction 41: Expected I, but found . m(ZB)Lcc;
00000 R I I . . . . . . . : : L0
00001 R I I . . . . . . . : : ALOAD 0
00002 R I I . . . . . . . : R : GETFIELD d.x : I
00003 R I I . . . . . . . : I : LDC 2036719157
00004 R I I . . . . . . . : I I : IMUL
00005 R I I . . . . . . . : I : ISTORE 3
00006 R I I I . . . . . . : : GOTO L1
00007 R I I I I I R . . . : : L2
00008 R I I I I I R . . . : : ALOAD 6
00009 R I I I I I R . . . : R : ICONST_0
00010 R I I I I I R . . . : R I : LDC -373364649
00011 R I I I I I R . . . : R I I : ALOAD 0
00012 R I I I I I R . . . : R I I R : GETFIELD d.at : I
00013 R I I I I I R . . . : R I I I : IMUL
00014 R I I I I I R . . . : R I I : ICONST_0
00015 R I I I I I R . . . : R I I I : INVOKEVIRTUAL cc.y (III)V
00016 R I I I I I R . . . : : GOTO L3
00017 ? : L4
00018 ? : ACONST_NULL
00019 ? : ARETURN
00020 R I I I I I . . . . : : L5
00021 R I I I I I . . . . : : ILOAD 1
00022 R I I I I I . . . . : I : IFEQ L6
00023 R I I I I I . . . . : : LDC -723220973
00024 ? : ALOAD 0
00025 ? : GETFIELD d.an : I
00026 ? : IMUL
00027 ? : ISTORE 3
00028 ? : LDC 1671960653
00029 ? : ALOAD 0
00030 ? : GETFIELD d.ad : I
00031 ? : IMUL
00032 ? : ISTORE 4
00033 ? : GOTO L7
00034 R I I I I I R . . . : : L8
00035 R I I I I I R . . . : : LDC 1955946639
00036 R I I I I I R . . . : I : ALOAD 0
00037 R I I I I I R . . . : I R : GETFIELD d.au : I
00038 R I I I I I R . . . : I I : IMUL
00039 R I I I I I R . . . : I : IFEQ L9
00040 R I I I I I R . . . : : L10
00041 R I I I I I R . . . : : IINC 7 1
00042 R I I I I I R I . . : : GOTO L11
00043 ? : L7
00044 ? : LDC 894092883
00045 ? : ALOAD 0
00046 ? : GETFIELD d.ac : I
00047 ? : IMUL
00048 ? : ISTORE 5
00049 ? : GOTO L6
00050 R I I I I I . . . . : : L12
00051 R I I I I I . . . . : : GETSTATIC d.b : Lem;
00052 R I I I I I . . . . : R : ILOAD 3
00053 R I I I I I . . . . : R I : ICONST_0
00054 R I I I I I . . . . : R I I : INVOKESTATIC cc.l (Lem;II)Lcc;
00055 R I I I I I . . . . : R : ASTORE 6
00056 R I I I I I R . . . : : ILOAD 4
00057 R I I I I I R . . . : I : ICONST_M1
00058 R I I I I I R . . . : I I : IF_ICMPEQ L13
00059 R I I I I I R . . . : : GETSTATIC d.b : Lem;
00060 ? : ILOAD 4
00061 ? : ICONST_0
00062 ? : INVOKESTATIC cc.l (Lem;II)Lcc;
00063 ? : ASTORE 7
00064 ? : GOTO L14
00065 ? : L15
00066 ? : ICONST_2
00067 ? : ANEWARRAY cc
00068 ? : DUP
00069 ? : ICONST_0
00070 ? : ALOAD 6
00071 ? : AASTORE
00072 ? : DUP
00073 ? : ICONST_1
00074 ? : ALOAD 7
00075 ? : AASTORE
00076 ? : ASTORE 8
00077 ? : GOTO L16
00078 ? : L17
00079 ? : GETSTATIC d.b : Lem;
00080 ? : ILOAD 5
00081 ? : ICONST_0
00082 ? : INVOKESTATIC cc.l (Lem;II)Lcc;
00083 ? : ASTORE 8
00084 ? : ICONST_3
00085 ? : ANEWARRAY cc
00086 ? : DUP
00087 ? : ICONST_0
00088 ? : ALOAD 6
00089 ? : AASTORE
00090 ? : DUP
00091 ? : ICONST_1
00092 ? : ALOAD 7
00093 ? : AASTORE
00094 ? : DUP
00095 ? : ICONST_2
00096 ? : ALOAD 8
00097 ? : AASTORE
00098 ? : ASTORE 9
00099 ? : NEW cc
00100 ? : DUP
00101 ? : ALOAD 9
00102 ? : ICONST_3
00103 ? : INVOKESPECIAL cc.<init> ([Lcc;I)V
00104 ? : ASTORE 6
00105 ? : GOTO L13
00106 R I I I I I R . . . : : L18
00107 R I I I I I R . . . : : ALOAD 6
00108 R I I I I I R . . . : R : ARETURN
00109 ? : L16
00110 ? : NEW cc
00111 ? : DUP
00112 ? : ALOAD 8
00113 ? : ICONST_2
00114 ? : INVOKESPECIAL cc.<init> ([Lcc;I)V
00115 ? : ASTORE 6
00116 R I I I I I R . . . : : L13
00117 R I I I I I R . . . : : ILOAD 1
00118 R I I I I I R . . . : I : IFNE L9
00119 R I I I I I R . . . : : ILOAD 2
00120 R I I I I I R . . . : I : ICONST_1
00121 R I I I I I R . . . : I I : IF_ICMPEQ L8
00122 R I I I I I R . . . : : NEW java/lang/IllegalStateException
00123 ? : DUP
00124 ? : INVOKESPECIAL java/lang/IllegalStateException.<init> ()V
00125 ? : ATHROW
00126 ? : L14
00127 ? : ILOAD 5
00128 ? : ICONST_M1
00129 ? : IF_ICMPEQ L15
00130 ? : ILOAD 2
00131 ? : ICONST_1
00132 ? : IF_ICMPEQ L17
00133 ? : NEW java/lang/IllegalStateException
00134 ? : DUP
00135 ? : INVOKESPECIAL java/lang/IllegalStateException.<init> ()V
00136 ? : ATHROW
00137 R I I I I . . . . . : : L19
00138 R I I I I . . . . . : : LDC 1642271889
00139 R I I I I . . . . . : I : ALOAD 0
00140 R I I I I . . . . . : I R : GETFIELD d.ay : I
00141 R I I I I . . . . . : I I : IMUL
00142 R I I I I . . . . . : I : ISTORE 5
00143 R I I I I I . . . . : : GOTO L5
00144 R I I I I I R . . . : : L9
00145 R I I I I I R . . . : : ILOAD 1
00146 R I I I I I R . . . : I : IFEQ L3
00147 R I I I I I R . . . : : ILOAD 2
00148 R I I I I I R . . . : I : ICONST_1
00149 R I I I I I R . . . : I I : IF_ICMPEQ L20
00150 R I I I I I R . . . : : NEW java/lang/IllegalStateException
00151 R I I I I I R . . . : R : DUP
00152 R I I I I I R . . . : R R : INVOKESPECIAL java/lang/IllegalStateException.<init> ()V
00153 R I I I I I R . . . : R : ATHROW
00154 R I I I I I R . . . : : L20
00155 R I I I I I R . . . : : ICONST_0
00156 R I I I I I R . . . : I : LDC -373364649
00157 R I I I I I R . . . : I I : ALOAD 0
00158 R I I I I I R . . . : I I R : GETFIELD d.at : I
00159 R I I I I I R . . . : I I I : IMUL
00160 R I I I I I R . . . : I I : IF_ICMPEQ L3
00161 R I I I I I R . . . : : ILOAD 2
00162 R I I I I I R . . . : I : ICONST_1
00163 R I I I I I R . . . : I I : IF_ICMPEQ L2
00164 R I I I I I R . . . : : NEW java/lang/IllegalStateException
00165 R I I I I I R . . . : R : DUP
00166 R I I I I I R . . . : R R : INVOKESPECIAL java/lang/IllegalStateException.<init> ()V
00167 R I I I I I R . . . : R : ATHROW
00168 R I I I I I R . . . : : L21
00169 R I I I I I R . . . : : ICONST_0
00170 R I I I I I R . . . : I : ISTORE 7
00171 R I I I I I R I . . : : GOTO L22
00172 R I I I I I R . . . : : L3
00173 R I I I I I R . . . : : ALOAD 0
00174 R I I I I I R . . . : R : GETFIELD d.c : [S
00175 R I I I I I R . . . : R : IFNULL L23
00176 R I I I I I R . . . : : ILOAD 2
00177 R I I I I I R . . . : I : ICONST_1
00178 R I I I I I R . . . : I I : IF_ICMPEQ L24
00179 R I I I I I R . . . : : NEW java/lang/IllegalStateException
00180 R I I I I I R . . . : R : DUP
00181 R I I I I I R . . . : R R : INVOKESPECIAL java/lang/IllegalStateException.<init> ()V
00182 R I I I I I R . . . : R : ATHROW
00183 R I I I I I R . . . : : L24
00184 R I I I I I R . . . : : ICONST_0
00185 R I I I I I R . . . : I : ISTORE 7
00186 R I I I I I R I . . : : GOTO L11
00187 R I I I I I R . . . : : L23
00188 R I I I I I R . . . : : ALOAD 0
00189 R I I I I I R . . . : R : GETFIELD d.a : [S
00190 R I I I I I R . . . : R : IFNULL L18
00191 R I I I I I R . . . : : ILOAD 2
00192 R I I I I I R . . . : I : ICONST_1
00193 R I I I I I R . . . : I I : IF_ICMPEQ L21
00194 R I I I I I R . . . : : NEW java/lang/IllegalStateException
00195 R I I I I I R . . . : R : DUP
00196 R I I I I I R . . . : R R : INVOKESPECIAL java/lang/IllegalStateException.<init> ()V
00197 R I I I I I R . . . : R : ATHROW
00198 R I I I I I R I . . : : L25
00199 R I I I I I R I . . : : ALOAD 6
00200 R I I I I I R I . . : R : ALOAD 0
00201 R I I I I I R I . . : R R : GETFIELD d.c : [S
00202 R I I I I I R I . . : R R : ILOAD 7
00203 R I I I I I R I . . : R R I : SALOAD
00204 R I I I I I R I . . : R I : ALOAD 0
00205 R I I I I I R I . . : R I R : GETFIELD d.m : [S
00206 R I I I I I R I . . : R I R : ILOAD 7
00207 R I I I I I R I . . : R I R I : SALOAD
00208 R I I I I I R I . . : R I I : INVOKEVIRTUAL cc.v (SS)V
00209 R I I I I I R I . . : : GOTO L10
00210 R I I I I I R I . . : : L11
00211 R I I I I I R I . . : : ILOAD 7
00212 R I I I I I R I . . : I : ALOAD 0
00213 R I I I I I R I . . : I R : GETFIELD d.c : [S
00214 R I I I I I R I . . : I R : ARRAYLENGTH
00215 R I I I I I R I . . : I I : IF_ICMPGE L23
00216 R I I I I I R I . . : : GOTO L25
00217 R I I I . . . . . . : : L1
00218 R I I I . . . . . . : : ALOAD 0
00219 R I I I . . . . . . : R : GETFIELD d.ar : I
00220 R I I I . . . . . . : I : LDC 608958183
00221 R I I I . . . . . . : I I : IMUL
00222 R I I I . . . . . . : I : ISTORE 4
00223 R I I I I . . . . . : : GOTO L19
00224 ? : L26
00225 ? : ALOAD 6
00226 ? : ICONST_0
00227 ? : LDC 1955946639
00228 ? : ALOAD 0
00229 ? : GETFIELD d.au : I
00230 ? : IMUL
00231 ? : ICONST_0
00232 ? : INVOKEVIRTUAL cc.y (III)V
00233 ? : GOTO L9
00234 R I I I I I R I . . : : L22
00235 R I I I I I R I . . : : ILOAD 7
00236 R I I I I I R I . . : I : ALOAD 0
00237 R I I I I I R I . . : I R : GETFIELD d.a : [S
00238 R I I I I I R I . . : I R : ARRAYLENGTH
00239 R I I I I I R I . . : I I : IF_ICMPGE L18
00240 R I I I I I R I . . : : ILOAD 2
00241 R I I I I I R I . . : I : ICONST_1
00242 R I I I I I R I . . : I I : IF_ICMPEQ L27
00243 R I I I I I R I . . : : NEW java/lang/IllegalStateException
00244 R I I I I I R I . . : R : DUP
00245 R I I I I I R I . . : R R : INVOKESPECIAL java/lang/IllegalStateException.<init> ()V
00246 R I I I I I R I . . : R : ATHROW
00247 R I I I I I R I . . : : L27
00248 R I I I I I R I . . : : ALOAD 6
00249 R I I I I I R I . . : R : ALOAD 0
00250 R I I I I I R I . . : R R : GETFIELD d.a : [S
00251 R I I I I I R I . . : R R : ILOAD 7
00252 R I I I I I R I . . : R R I : SALOAD
00253 R I I I I I R I . . : R I : ALOAD 0
00254 R I I I I I R I . . : R I R : GETFIELD d.e : [S
00255 R I I I I I R I . . : R I R : ILOAD 7
00256 R I I I I I R I . . : R I R I : SALOAD
00257 R I I I I I R I . . : R I I : INVOKEVIRTUAL cc.s (SS)V
00258 R I I I I I R I . . : : IINC 7 1
00259 R I I I I I R I . . : : GOTO L22
00260 R I I I I I . . . . : : L6
00261 R I I I I I . . . . : : ILOAD 3
00262 R I I I I I . . . . : I : ICONST_M1
00263 R I I I I I . . . . : I I : IF_ICMPNE L12
00264 R I I I I I . . . . : : GOTO L4
00265 R I I . . . . . . . : R : L28
00266 R I I . . . . . . . : R : NEW java/lang/StringBuilder
00267 R I I . . . . . . . : R R : DUP
00268 R I I . . . . . . . : R R R : INVOKESPECIAL java/lang/StringBuilder.<init> ()V
00269 R I I . . . . . . . : R R : LDC "af.m("
00270 R I I . . . . . . . : R R R : INVOKEVIRTUAL java/lang/StringBuilder.append (Ljava/lang/String;)Ljava/lang/StringBuilder;
00271 R I I . . . . . . . : R R : LDC 41
00272 R I I . . . . . . . : R R I : INVOKEVIRTUAL java/lang/StringBuilder.append (C)Ljava/lang/StringBuilder;
00273 R I I . . . . . . . : R R : INVOKEVIRTUAL java/lang/StringBuilder.toString ()Ljava/lang/String;
00274 R I I . . . . . . . : R R : INVOKESTATIC b.b (Ljava/lang/Throwable;Ljava/lang/String;)Lcd;
00275 R I I . . . . . . . : R : ATHROW
TRYCATCHBLOCK L0 L28 L28 java/lang/RuntimeException
How can I remove the exceptions properly so that I don't get the above errors? It seems like a "Frame" error/problem but I'm not sure how to fix it. Any ideas?
475
Removing the athrow instruction removes an edge in the control-flow graph, so the verifier now must prove the code is safe if execution falls out of the block formerly containing the athrow. In this case, it cannot ensure a local has been initialized to an int for the iinc instruction on line 41.
The simplest solution is to replace the new; dup; invokespecial java/lang/IllegalStateException/<init>()V; athrow sequence with a constant return (in this case, aconst_null; aret, but that will change to match the return type). This enables the verifier to prove control does not exit the block. (Note that this effectively skips finally handlers by not branching to the catch block.)
In comments, the querent explained they're doing control-flow deobfuscation. In general, you're better off building a high-level SSA-style IR with an explicit control-flow graph and transforming that, rather than working at the level of the operand stack and local variables. On such an IR it's pretty easy to say 'I know this branch is never taken, replace it with a jump to the not-taken block`. Such an IR takes some effort to build (through there are some existing analysis frameworks like Soot), but it will pay for itself many times over if you're doing more than one transformation or need to handle many different code patterns (so simple pattern-matching on bytecode sequences is ineffective).
83
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
