Cortex-A15 (codename Eagle) is the successor to the Cortex-A9, a low-power high-performance ARMmicroarchitecture designed by ARM Holdings for the mobile market. This microarchitecture is designed as a synthesizable IP core and is sold to other semiconductor companies to be implemented in their own chips. The A15 is the first microarchitecture specifically designed for high-performance, whereas the Cortex-A7, also the successor to the Cortex-A9, target high-efficiency.
The Cortex-A15 was often combined with a number of lower power cores (e.g. Cortex-A7) in a big.LITTLE configuration to achieve better energy/performance.
One can specify NEON support using the -mfpu=neon option. Note that GCC will not generate floating-point operations for auto-vectorization constructs because NEON, under ARMv7, is not fully IEEE 754-compliant. It's possible to use -funsafe-math-optimizations to circumvent that behavior.
If the Cortex-A15 is coupled with the Cortex-A7 in a big.LITTLE system, GCC also supports the following option: