--allow_fpreg_for_nonfpdata enables the compiler to use VFP and NEON registers and instructions for data transfer operations on non-VFP and non-NEON data. This is useful when demand for integer registers is high. For the compiler to use the VFP or NEON registers, the default FPU or the specified --fpu option must be any hardware VFP option or the NEON unit must be enabled.

--no_allow_fpreg_for_nonfpdata prevents VFP and NEON registers from being used for non-VFP and non-NEON data. When this option is specified, the compiler uses VFP and NEON registers for VFP and NEON data only. This is useful when you want to confine the number of places in your code where the compiler generates VFP or NEON instructions.

The default is --allow_fpreg_for_nonfpdata.