[cker/ruy] EXPERIMENTAL_RUY_FEATURE flag not working for android

[periannath]

EXPERIMENTAL_RUY_FEATURE flag is introduced in #3446.

This flag works well on arm32 linux, but it is not working on arm64 android.

I'll investigate the reason of this error.

/cc @YongseopKim

[periannath]

dynamic_cast in FullyConnectedLayer.cc produces nullptr for correct casting

ONE/runtime/onert/backend/cpu/ops/FullyConnectedLayer.cc

Line 135 in 60dd708

auto weight_tensor = dynamic_cast<const Tensor *>(_weights);

• This dynamic_cast works correctly on arm32 linux
• Produces nullptr only at arm64 android

I found some pages explain about dynamic_cast in Android

• NDK document for common problems

  Problem: Exceptions are not being caught when thrown across shared library boundaries, or dynamic_cast is failing.
  Solution: Add a key function to your types. A key function is the first non-pure, out-of-line virtual function for a type. For an example, see the discussion on Issue 533.

• How to add a key function

In summary

• dynamic_cast is not working across shared library boundaries (NDK only)
  • Declared type of _weight is IPortableTensor defined at libonert_core.so
  • Actual type of _weight is cpu_common::Tensor defined at libbackend_cpu.so
• Solution
  • Method 1 : Add a key function to IPortableTensor and cpu_common::Tensor
    • Problem : Thers's no cpp file for IPortableTensor
  • Method 2 : Using static_cast instead of dynamic_cast
    • Problem : Type check for polymorphism is missing
    • Maybe use nnfw::misc::polymorphic_downcast instead of static_cast?

[periannath]

Method 2 runs well on android. I've uploaded PR #3654.

[periannath]

Fixed by #3654.