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# setStageInRegion(_:)

Sets the dimensions over the thread grid of how your compute kernel receives stage-in arguments.

```
func setStageInRegion(_ region: MTLRegion)
```

## Parameters

`region`

The [`MTLRegion`](/documentation/Metal/MTLRegion) defining how to interpret a thread’s location as a coordinate for stage-in data.

## Discussion

The region’s origin point, starting from `(0,0,0)` in the upper left of the bound data, determines the final index of `[[stage_in]]` data. Note that the total number of threads Metal launches may be larger than your stage-in data.

To determine the index used to fetch `[[stage_in]]` data for a given thread, the GPU adds the values specified by the region’s origin to the thread position in the grid. Threads in the grid outside of the maximum stage-in data size have undefined behavior when accessing the stage-in memory region.

---

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