It's not specific to SSA, though SSA assumes it's working with basic blocks (as do a lot of compiler algorithms). And yeah, writeups of compiler theory (and com

It's not specific to SSA, though SSA assumes it's working with basic blocks (as do a lot of compiler algorithms). And yeah, writeups of compiler theory (and compiler practice) are where to go for more detailed discussion. The core idea I think is that control flow complicates the kinds of analysis a lot of optimisation and other compiler passes need to do; so by first breaking the input into pieces which have very restricted possible flows of control ("only entered at the top, only exited at the bottom" is the classic definition) then: 1. You can get quite a long way with optimisations that only work within a basic block, and the restriction to within-a-BB simplifies things a lot because it can entirely ignore control flow 2. Analysis that only cares about control flow can work on a graph of BBs and ignore the individual-statement/instruction details, because the BB graph captures all the detail of what can branch where