Open Radar

 
Summary:
When writing a Core Image Kernel Language Shader, it automatically gets translated to Metal under iOS 10. In our case this translation fails because the `greaterThanEqual` function is apparently unavailable. This is especially severe since there seems to be no way of deactivating this automatic translation for UIKit apps.

Here’s the output from my example project:

Metal library creation failed with error: Error Domain=MTLLibraryErrorDomain Code=3 "Compilation failed: 



program_source:48:22: error: use of undeclared identifier 'greaterThanEqual'

  bool isWhite = all(greaterThanEqual(float3(pixel), float3(tolerance)));

                     ^

" UserInfo={NSLocalizedDescription=Compilation failed: 



program_source:48:22: error: use of undeclared identifier 'greaterThanEqual'

  bool isWhite = all(greaterThanEqual(float3(pixel), float3(tolerance)));

                     ^

Steps to Reproduce:

I’ve uploaded a minimal example project that reproduces the issue here: https://github.com/Ben-G/AppleBugProjects/tree/master/MetaliOS10Issue/SheetCompareTestiOS10

It simply loads an image, applies a Core Image Kernel Shader to it and attempts to add it to a UIImageView. On iOS 10 devices this operation fails with output shown above.

Expected Results:
The shader keeps working as it did on iOS 8 and iOS 9.

Actual Results:
The automatic translation fails and results in an empty image instead of an image that is transformed through the shader.