What does 'function too large' mean?

Hi experts：
I created a library in IVc4. During normal compilation, there is no error message. But when selecting "Compile + Debug", this kind of error occurred:

Fatal Error ： Function 'XXXXXXX' too large.

I searched the forum, but did not see anything similar to mine.I checked the "known limits" section in ivc4 manual, and I don't know if the "maximum branch of BIC." limit has been exceeded. It says this:

- maximum BRANCH of 32K
BRANCH means the part of generated object code per function,including macros etc.

If this is the case, then I don't understand why the error is reported only when "Compile + Debug", but everything is normal when compiling.
If debugging is not possible, the library cannot be used. So how should I solve this problem? Split this function?

Thanks.