pub unsafe fn filled_value(
        &mut self,
        builder: LLVMBuilderRef,
        value: LLVMValueRef,
    ) -> LLVMValueRef {
        let filled_pointer = LLVMBuildStructGEP(builder, value, FILLED_INDEX, c_str!(""));
        LLVMBuildLoad(builder, filled_pointer, c_str!("slot.filledValue"))
    }
Return the filled value (used for grouping dictionaries).

The slot should be a pointer.
weld/src/codegen/llvm2/dict.rs