Java Opcodes.IFEQ属性代码示例

private static If.Type ifType(int opcode) {
  switch (opcode) {
    case Opcodes.IFEQ:
    case Opcodes.IF_ICMPEQ:
    case Opcodes.IF_ACMPEQ:
      return If.Type.EQ;
    case Opcodes.IFNE:
    case Opcodes.IF_ICMPNE:
    case Opcodes.IF_ACMPNE:
      return If.Type.NE;
    case Opcodes.IFLT:
    case Opcodes.IF_ICMPLT:
      return If.Type.LT;
    case Opcodes.IFGE:
    case Opcodes.IF_ICMPGE:
      return If.Type.GE;
    case Opcodes.IFGT:
    case Opcodes.IF_ICMPGT:
      return If.Type.GT;
    case Opcodes.IFLE:
    case Opcodes.IF_ICMPLE:
      return If.Type.LE;
    default:
      throw new Unreachable("Unexpected If instruction opcode: " + opcode);
  }
}
 

@SuppressWarnings("unused")
protected void onMethodEnter() {
	if (done) return;

	overridden = true;
	Label start  = new Label();
	Label normal = new Label();
	super.visitLabel(start);
	super.visitFieldInsn(Opcodes.GETSTATIC, CONFIGURATION, CONFIGURATION_FIELD_NAME, Type.INT_TYPE.getDescriptor());
	super.visitInsn(Opcodes.DUP);
	super.visitJumpInsn(Opcodes.IFEQ, normal);
	super.visitInsn(Opcodes.IRETURN);
	super.visitLabel(normal);
	super.visitInsn(Opcodes.POP);
	Label end = new Label();
	super.visitJumpInsn(Opcodes.GOTO, end);
	super.visitLabel(end);
	super.visitTryCatchBlock(start, normal, end, Type.getType(Throwable.class).getDescriptor());
}
 

/**
 * This are values compared against 0, like {@code value < 0}
 *
 * @return
 */
public static Truthness getForSingleValueJump(int value, int opcode) {

    switch (opcode) {
        case Opcodes.IFEQ: // ie, val == 0
            return getForValueComparison(value, 0, Opcodes.IF_ICMPEQ);

        case Opcodes.IFNE: // ie val != 0  ->  ! (val == 0)
            return getForSingleValueJump(value, Opcodes.IFEQ).invert();

        case Opcodes.IFLT: // ie, val < 0
            return getForValueComparison(value, 0, Opcodes.IF_ICMPLT);

        case Opcodes.IFGE: // ie, val >= 0  -> ! (val < 0)
            return getForSingleValueJump(value, Opcodes.IFLT).invert();

        case Opcodes.IFLE: // ie, val <= 0  ->  0 >= val  -> ! (0 < val)
            return getForValueComparison(0, value, Opcodes.IF_ICMPLT).invert();

        case Opcodes.IFGT: // ie, val > 0  ->  0 < val
            return getForValueComparison(0, value, Opcodes.IF_ICMPLT);

        default:
            throw new IllegalArgumentException("Cannot handle opcode " + opcode);
    }
}
 

@Test
public void test_IFEQ_posNeg() {
    //val == 0
    int code = Opcodes.IFEQ;
    int val = +1;

    Truthness tneg = getForSingleValueJump(-val, code);
    assertFalse(tneg.isTrue());
    assertTrue(tneg.isFalse());

    Truthness tpos = getForSingleValueJump(+val, code);
    assertFalse(tpos.isTrue());
    assertTrue(tpos.isFalse());

    // +1 and -1 should lead to same branch distance
    assertTrue(tneg.getOfTrue() < 1d);
    assertEquals(tneg.getOfTrue(), tpos.getOfTrue(), 0.001);
}
 

private int[] getJumpTargets(JumpInsnNode jump) {
  switch (jump.getOpcode()) {
    case Opcodes.IFEQ:
    case Opcodes.IFNE:
    case Opcodes.IFLT:
    case Opcodes.IFGE:
    case Opcodes.IFGT:
    case Opcodes.IFLE:
    case Opcodes.IF_ICMPEQ:
    case Opcodes.IF_ICMPNE:
    case Opcodes.IF_ICMPLT:
    case Opcodes.IF_ICMPGE:
    case Opcodes.IF_ICMPGT:
    case Opcodes.IF_ICMPLE:
    case Opcodes.IF_ACMPEQ:
    case Opcodes.IF_ACMPNE:
    case Opcodes.IFNULL:
    case Opcodes.IFNONNULL:
      return new int[]{getOffset(jump.label), getOffset(jump.getNext())};
    case Opcodes.GOTO:
      return new int[]{getOffset(jump.label)};
    case Opcodes.JSR: {
      throw new Unreachable("JSR should be handled by the ASM jsr inliner");
    }
    default:
      throw new Unreachable("Unexpected opcode in jump instruction: " + jump);
  }
}
 

/**
 * Imports branch instructions, both conditional and unconditional.
 *
 * @param opcode Opcode.
 * @param label  Destination of branch.
 */
@Override
public void visitJumpInsn(final int opcode, final Label label) {
  BasicBlock section = getBasicBlock(label);
    
  switch(opcode) {
    // Unconditional Branch
    case Opcodes.GOTO: finishBlock(section); setCurrent(null); break;
    
    // Zero Test
    case Opcodes.IFEQ: createZeroCondition(Condition.Operator.EQ, section); break;
    case Opcodes.IFNE: createZeroCondition(Condition.Operator.NE, section); break;
    case Opcodes.IFLT: createZeroCondition(Condition.Operator.LT, section); break;
    case Opcodes.IFGE: createZeroCondition(Condition.Operator.GE, section); break;
    case Opcodes.IFGT: createZeroCondition(Condition.Operator.GT, section); break;
    case Opcodes.IFLE: createZeroCondition(Condition.Operator.LE, section); break;
    
    // Integer Comparison
    case Opcodes.IF_ICMPEQ: createCondition(Condition.Operator.EQ, section); break;
    case Opcodes.IF_ICMPNE: createCondition(Condition.Operator.NE, section); break;
    case Opcodes.IF_ICMPLT: createCondition(Condition.Operator.LT, section); break;
    case Opcodes.IF_ICMPGE: createCondition(Condition.Operator.GE, section); break;
    case Opcodes.IF_ICMPGT: createCondition(Condition.Operator.GT, section); break;
    case Opcodes.IF_ICMPLE: createCondition(Condition.Operator.LE, section); break;

    // Reference Comparisons
    case Opcodes.IF_ACMPEQ: createCondition(Condition.Operator.EQ, section); break;
    case Opcodes.IF_ACMPNE: createCondition(Condition.Operator.NE, section); break;
    case Opcodes.IFNULL:    createNullCondition(Condition.Operator.EQ, section); break;
    case Opcodes.IFNONNULL: createNullCondition(Condition.Operator.NE, section); break;
    
    // TODO: JSR (paired with RET)
    case Opcodes.JSR: System.err.println("visitJumpInsn: JSR");
  }
}
 

@Test
public void test_IFEQ_0() {
    //val == 0
    int code = Opcodes.IFEQ;

    Truthness t0 = getForSingleValueJump(0, code);
    assertTrue(t0.isTrue());
    assertFalse(t0.isFalse());
}
 

@Test
public void test_IFEQ_incr() {
    //val == 0
    int code = Opcodes.IFEQ;

    Truthness a = getForSingleValueJump(1, code);
    Truthness b = getForSingleValueJump(-10, code);

    assertTrue(a.isFalse());
    assertTrue(b.isFalse());

    // 1 is closer to 0
    assertTrue(a.getOfTrue() > b.getOfTrue());
}
 

@Override
public void visitJumpInsn(final int opcode, final Label label) {
    switch (opcode) {
    case Opcodes.IFEQ:
        ifeq(label);
        break;
    case Opcodes.IFNE:
        ifne(label);
        break;
    case Opcodes.IFLT:
        iflt(label);
        break;
    case Opcodes.IFGE:
        ifge(label);
        break;
    case Opcodes.IFGT:
        ifgt(label);
        break;
    case Opcodes.IFLE:
        ifle(label);
        break;
    case Opcodes.IF_ICMPEQ:
        ificmpeq(label);
        break;
    case Opcodes.IF_ICMPNE:
        ificmpne(label);
        break;
    case Opcodes.IF_ICMPLT:
        ificmplt(label);
        break;
    case Opcodes.IF_ICMPGE:
        ificmpge(label);
        break;
    case Opcodes.IF_ICMPGT:
        ificmpgt(label);
        break;
    case Opcodes.IF_ICMPLE:
        ificmple(label);
        break;
    case Opcodes.IF_ACMPEQ:
        ifacmpeq(label);
        break;
    case Opcodes.IF_ACMPNE:
        ifacmpne(label);
        break;
    case Opcodes.GOTO:
        goTo(label);
        break;
    case Opcodes.JSR:
        jsr(label);
        break;
    case Opcodes.IFNULL:
        ifnull(label);
        break;
    case Opcodes.IFNONNULL:
        ifnonnull(label);
        break;
    default:
        throw new IllegalArgumentException();
    }
}