- Enable shaderSignedZeroInfNanPreserveFloat16 and
shaderSignedZeroInfNanPreserveFloat32.
Other float control properties are not settable in Metal.
- MVKShaderModule log whether compiling with fast math enabled.
- Update MoltenVK_Runtime_UserGuide.md and Whats_New.md documents.
- runcts script enable MVK_CONFIG_FAST_MATH_ENABLED by default.