primeant

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![img_1066](https://cloud.githubusercontent.com/assets/14350352/18507169/c11aeeae-7aa1-11e6-9422-868d04535dbc.PNG) ![img_1070](https://cloud.githubusercontent.com/assets/14350352/18507170/c11d47ee-7aa1-11e6-96c1-8d3ee939bfad.PNG)

比如拦截一个名CaptureMTLDevice类,forwardInvocation也没走,然后就挂掉了,请问需要怎么处理?谢谢。

How to convert the generated .ll file back to .air, using `xcrun metal -x metal -c input.ll -o output.air` will report an error