that future processors execute the most restrictive version of the function the
new processor can execute.
+In addition, unlike the ICC implementation of this feature, the selection of the
+version does not consider the manufacturer or microarchitecture of the processor.
+It tests solely the list of features that are both supported by the specified
+processor and present in the compiler-rt library. This can be surprising at times,
+as the runtime processor may be from a completely different manufacturer, as long
+as it supports the same feature set.
+
+This can additionally be surprising, as some processors are indistringuishable from
+others based on the list of testable features. When this happens, the variant
+is selected in an unspecified manner.
+
Function versions are defined with ``cpu_specific``, which takes one or more CPU
names as a parameter. For example: