[michalharakal]

Problem

MmapFloatTensorData didn't override copyToFloatArray(), so it used the TensorData default. That walks every element through get(*indices): an IntArray copy for the vararg spread plus a boxed Float per element.

RMSNormalization.eagerFusedRmsNorm copies its gain tensor on every forward, and with MAPPED weights the gains are MmapFloatTensorData. In a BitNet b1.58 2B4T JVM decode profile, this was the top allocation site once the Vector API fallback was fixed (#1360): about 10 GB in a 45 s window. It also showed up in CPU samples as MmapFloatTensorData.calcFlatIndex.

Change

An override that does one bulk read:

override fun copyToFloatArray(): FloatArray {
    val out = FloatArray(shape.volume)
    val view = floatBuffer.duplicate()   // the shared view's position stays untouched
    view.position(0)                     // separate statements: Android's pre-Java-9 nio returns Buffer
    view.get(out)
    return out
}

It copies exactly shape.volume floats in row-major order, which is the same contract as the default. apiCheck passes.

Tests

New MmapFloatTensorDataCopyTest (lang-core jvmTest, 3 tests):

• the bulk copy equals the element-wise get order for a rank-3 tensor;
• only volume floats are copied from a larger buffer;
• a slice at a nonzero byte offset (the way MmapTensorSource slices) copies correctly, the shared floatBuffer.position() stays 0, and the copy is repeatable.

:skainet-lang:skainet-lang-core:jvmTest passes 1046/1046.

Measured

Arduino Ventuno Q, 4× Cortex-A78C, JVM, BitNet 2B4T I2_S, 128 greedy tokens, backported onto 0.61.0:

• the TensorData.copyToFloatArray ← MmapFloatTensorData ← eagerFusedRmsNorm element-wise site disappears from JFR. MmapFloatTensorData.copyToFloatArray remains only as one bulk array per call (~3.8 % of allocation);
• greedy output is byte-identical (md5 52f57d1d…);
• decode goes 2.33 → 2.36 tok/s (within noise; on the JVM this is an allocation fix rather than a wall-time one).

Possible follow-up: cache the gain in RMSNormalization so even the bulk copy happens once.

Refs #1357

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