Forces depth-stencil testing before a shader executes.
Depth-stencil testing is normally done during pixel processing by a pixel shader. Forcing early depth-stencil testing causes the testing to be done prior to the shader execution; the purpose is to improve per-pixel performance by culling/reducing/avoiding unnecessary pixel processing.
An application can force early depth-stencil testing by supplying the attribute or the hardware may execute early depth-stencil testing provided no depth values are written and no unordered access operations are performed in a shader as an optimization.
This attribute is supported in the following types of shaders: