pxb1988/dex2jar · error · CantNotFixContentException

#+BBBB0000

Error message

#+BBBB0000

What it means

CodeWriter.build21h assembles the 21h instruction format (const/const-wide/high16), which stores only the high 16 bits of the constant; the low bits must be zero. If a CONST_HIGH16 value has any non-zero low 16 bits, the instruction cannot represent it exactly, so CantNotFixContentException is thrown with message '#+BBBB0000'.

Solutions

1. Mask-check the constant: only use CONST_HIGH16 when (v & 0xFFFF) == 0, otherwise emit CONST_32 (CONST).
2. Change the emitted opcode to CONST (31i format) for arbitrary 32-bit constants.
3. Fix the opcode-selection logic in visitConstStmt/optimizer to test low bits before choosing 21h.
4. Catch CantNotFixContentException around const emission and fall back to the wide format.

Example fix

// before: assumes magnitude implies encodable
emitConst(CONST_HIGH16, a, 0x12345678);
// after: choose format by value shape
if ((v & 0xFFFF) == 0) emitConst(CONST_HIGH16, a, v); else emitConst(CONST, a, v);

boolean fitsConstHigh16(int v) { return (v & 0xFFFF) == 0; }

try {
    emitConst(CONST_HIGH16, a, v);
} catch (CantNotFixContentException e) {
    emitConst(CONST, a, v); // fall back to full 32-bit const
}

When it happens

Trigger: visitConstStmt dispatching a CONST_HIGH16 op whose int value has (v & 0xFFFF) != 0, e.g. const/high16 with literal 0x12345678.

Common situations: Constant folding or translation pipelines that select the high16 opcode based only on magnitude without checking the low bits are zero; writing optimizers that replace const with const/high16 as a size optimization incorrectly.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• #+BBBB000000000000
• #+BBBB
• #+BBBBBBBB
• A
• while accept code in method

AI-assisted analysis of pxb1988/dex2jar@b5bda4fb49 (2026-09-08). Data as JSON: /api/errors/1bc49b995dd13319. Report an issue: GitHub.

Appendix: source

Thrown at dex-writer/src/main/java/com/googlecode/d2j/dex/writer/CodeWriter.java:182

    // B|A|op
    private byte[] build12x(Op op, int vA, int vB) {
        checkRegA(op, "vA", vA);
        checkRegA(op, "vB", vB);
        b.position(0);
        b.put((byte) op.opcode).put((byte) ((vA & 0xF) | (vB << 4)));

        return copy(b);
    }

    // AA|op BBBB
    private byte[] build21h(Op op, int vAA, Number value) {
        checkRegAA(op, "vAA", vAA);
        int realV;
        if (op == CONST_HIGH16) { // op vAA, #+BBBB0000
            int v = ((Number) value).intValue();
            if ((v & 0xFFFF) != 0) {
                throw new CantNotFixContentException(op, "#+BBBB0000", v);
            }
            realV = v >> 16;

        } else { // CONST_WIDE_HIGH16 //op vAA, #+BBBB000000000000
            long v = ((Number) value).longValue();
            if ((v & 0x0000FFFFffffFFFFL) != 0) {
                throw new CantNotFixContentException(op, "#+BBBB000000000000", v);
            }
            realV = (int) (v >> 48);
        }
        b.position(0);
        b.put((byte) op.opcode).put((byte) vAA).putShort((short) realV);
        return copy(b);
    }

    // AA|op BBBB
    private byte[] build21s(Op op, int vAA, Number value) {
        checkRegAA(op, "vAA", vAA);

View on GitHub (pinned to b5bda4fb49)