The iPhone 5's A6 SoC: Not A15 or A9, a Custom Apple Core Instead

http://www.anandtech.com/show/6292/iphone-5-a6-not-a15-custom-core

Only the Cortex A5, A7 and A15 support the VFPv4 extensions to the ARMv7-A ISA. The Cortex A8 and A9 top out at VFPv3. If you want to get really specific, the Cortex A5 and A7 implement a 16 register VFPv4 FPU, while the A15 features a 32 register implementation. The point is, if your architecture supports VFPv4 then it isn't a Cortex A8 or A9.