FuelLabs/sway · error

Pointer offset must be in data_section

Error message

Pointer offset must be in data_section

What it means

In realize_load, for a non-copy-type load the compiler synthesizes a pointer entry (the byte offset of the target relative to the load instruction) and appends it at the end of the data section via data_id_of_pointer. That lookup is expected to always succeed because the pointer was just appended; if it returns None, the newly created pointer entry is not found in the data section, meaning an internal miscalculation in data-section bookkeeping (e.g. the append failed or offsets/ids are out of sync).

Source

Thrown at sway-core/src/asm_lang/allocated_ops.rs:1066

    );
    let offset = match imm {
        Ok(value) => value,
        Err(_) => panic!(
            "Unable to offset into the data section more than 2^12 bits. \
                                Unsupported data section length: {offset_words} words."
        ),
    };

    if !has_copy_type {
        // Load the pointer itself into the register. `offset_to_data_section` is in bytes.
        // The -4 is because $pc is added in the *next* instruction.
        let pointer_offset_from_current_instr =
            offset_to_data_section - offset_from_instr_start + offset_bytes - 4;

        // Insert the pointer as bytes as a new data section entry at the end of the data.
        let data_id_for_pointer = data_section
            .data_id_of_pointer(pointer_offset_from_current_instr)
            .expect("Pointer offset must be in data_section");

        // Now load the pointer we just created into the `dest`ination.
        let mut buf = Vec::with_capacity(2);
        buf.append(&mut realize_load(
            dest,
            &data_id_for_pointer,
            data_section,
            offset_to_data_section,
            offset_from_instr_start,
        ));
        // Add $pc to the pointer since it is relative to the current instruction.
        buf.push(
            fuel_asm::op::ADD::new(
                dest.to_reg_id(),
                dest.to_reg_id(),
                ConstantRegister::ProgramCounter.to_reg_id(),
            )
            .into(),

View on GitHub (pinned to dad95cc42b)

Solutions

1. Verify data_id_of_pointer appends-and-returns atomically so the just-inserted pointer is always found
2. Check that pointer_offset_from_current_instr arithmetic matches what data_id_of_pointer uses as its key
3. Inspect data section insertion for silent failures or id/offset desynchronization between append and lookup

When it happens

Trigger: Thrown at sway-core/src/asm_lang/allocated_ops.rs:1066 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of FuelLabs/sway@dad95cc42b (2026-09-04). Data as JSON: /api/errors/0150dcaf2d8d7081. Report an issue: GitHub.