[harshith-roy]

Summary

This change improves IEEE-754 exceptional-value handling and subnormal accuracy in the NEON and SVE FP32 logarithm implementations.

It also fixes an FP16 SOFT_RELU overflow regression exposed by the corrected logarithm behavior.

Changes

• Add IEEE-754 classification and exceptional-value handling to NEON and SVE FP32 Log.
• Handle positive FP32 subnormal inputs through normalization.
• Return appropriate results for zero, negative inputs, infinities and NaNs.
• Preserve the legacy logarithm implementation for Pow to avoid changing its existing behavior.
• Fix FP16 SOFT_RELU overflow handling in NEON and SVE.
• Add regression tests for exceptional logarithm inputs, vector boundaries, subnormal accuracy and SOFT_RELU overflow.

Validation

Validated using AArch64 cross-compilation and QEMU user-mode emulation.

• NEON ElementwiseLog: 213/213
• SVE ElementwiseLog: 213/213 at vector lengths 16, 32 and 64 bytes.
• NEON ActivationLayer: 929/929
• SVE ActivationLayer: 929/929 at vector lengths 16, 32 and 64 bytes.
• NEON Softmax and LogSoftmax: 528/528.

Both NEON and SVE builds passed with warnings treated as errors.

Note: Runtime validation was performed under QEMU, not physical ARM hardware.