How to compile sqrtf function

Hi, I'm trying to porting some C code from armcc tool-chain to gnu tool-chain.

By ARMCC, it seems __sqrtf is intrinsic in libm.a and will be compiled into VSQRT.F32 instruction.

By ARM-NONE-EABI-GCC, it seems sqrtf in libm.a is performed by a function of many instructions, even I used the following compiler options

-mcpu=cortex-m4 -mthumb -mfloat-abi=hard -mfpu=fpv4-sp-d16

The compiler doesn't pass arguments to sqrtf function in fp registers

Any ideas, guys?

Thanks.