The `step` instrumentation shouldn't be treated, during use, like an `increment`. The latter is treated as a BB ID. The step isn't that, it's more of a type of value profiling. We need to distinguish between the 2 when really looking for BB IDs (==increments), and handle appropriately `step`s. In particular, we need to know when to elide them because `select`s may get elided by function cloning, if the condition of the select is statically known.
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