[taronaeo]

Overview

fixes #28281

I forgot to use vec_splats(0.0f) when accumulating, and instead used v_acc, which was undefined. Quoting @IgorTodorovskiIBM:

v_acc is declared const inside the loop body and has no prior value, so the third operand of vec_madd is whatever the register happens to hold. The accumulated sumf is therefore garbage, and can be NaN or Inf depending on the residue.

Relatively simple fix, not sure how I overlooked it.

Requirements

• I have read and agree with the contributing guidelines
• AI usage disclosure: 没有

[taronaeo]

cc: @AlekseiNikiforovIBM @Andreas-Krebbel for a quick check

[AlekseiNikiforovIBM]

LGTM