Can Cortex A8 NEON optimized code work on Cortex A5 NEON?

Both Cortex-A8 and Cortex-A5 are Armv7-A architectural processors.  The NEON instructions are similar.

However, Cortex-A5 can support those options:

• No FPU or NEON support
• FPU only
• with FPU and NEON support

Cortex-A8 can support those options:

• No FPU or NEON support
• With FPU and NEON support

Compiler options

• Armcc --cpu=Cortex-A5 (core has neither)
• Armcc --cpu=Cortex-A5.vfp (core has FPU only)
• Armcc --cpu=Cortex-A5.neon (core has NEON and FPU)
• armcc --cpu=Cortex-A8 (core has NEON and FPU)
• armcc --cpu=Cortex-A8.no_neon (core has neither VFP or NEON)

When you talked about "Cortex-A8 code heavily utilized the NEON VFPU" for Cortex-A5, you can judge based on above information.

Cortex-A8 and Cortex-A5 are based on the same architecture, A8 NEON code can run on Cortex-A5, but it might produce different performance gains.