These options enable or disable the use of VFP and NEON registers and data transfer instructions for non-VFP and non-NEON data.
--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 options for the processor
or the specified options must enable the hardware.
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.