Philip Reames 31c37a4a5e [RISCV][TTI] Adjust VLS shuffle costing to account for sub-mask reuse (#129793) ...

If we have a shuffle which can be split via VLA where two or more of the
destinations have exactly the same elements, then we only need to
account for them once in costing. The duplicate copies are are (at
worst) whole register moves.

Note that this change only handles the single source case. Doing the
multiple source case seemed a bit more complicated, and I didn't have a
motivating test case.

2025-03-29 15:18:44 -07:00

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