On Cortex-M4F microcontrollers: is fixed point math faster or floating point?

Intrinsic functions are more commonly used for 'non C' type actions, such as barrier instructions. In higher order code, the compiler will generate VFP instructions automatically when compiled for VFP. If you really want to hand craft a function, you would use assembler, rather than intrinsics. For example:

float foo(float a, float b){
  return (a+b);
}

Compiled with:

armclang -c -O2 --target=arm-arm-none-eabi -mcpu=cortex-m4 -mfpu=vfpv3 float.c

outputs:

    foo
        0x00000000:    ee001a10    ....    VMOV     s0,r1
        0x00000004:    ee010a10    ....    VMOV     s2,r0
        0x00000008:    ee310a00    1...    VADD.F32 s0,s2,s0
        0x0000000c:    ee100a10    ....    VMOV     r0,s0
        0x00000010:    4770        pG      BX       lr

For completeness, when compiled without VFP it calls a library function, which will take many cycles

    foo
        0x00000000:    f7ffbffe    ....    B.W      __aeabi_fadd

Intrinsic functions are more commonly used for 'non C' type actions, such as barrier instructions. In higher order code, the compiler will generate VFP instructions automatically when compiled for VFP. If you really want to hand craft a function, you would use assembler, rather than intrinsics. For example:

float foo(float a, float b){
  return (a+b);
}

Compiled with:

armclang -c -O2 --target=arm-arm-none-eabi -mcpu=cortex-m4 -mfpu=vfpv3 float.c

outputs:

    foo
        0x00000000:    ee001a10    ....    VMOV     s0,r1
        0x00000004:    ee010a10    ....    VMOV     s2,r0
        0x00000008:    ee310a00    1...    VADD.F32 s0,s2,s0
        0x0000000c:    ee100a10    ....    VMOV     r0,s0
        0x00000010:    4770        pG      BX       lr

For completeness, when compiled without VFP it calls a library function, which will take many cycles

    foo
        0x00000000:    f7ffbffe    ....    B.W      __aeabi_fadd