> Implementing SSA construction is hard. To save its users from having to implement it, LLVM provides stack slots. This means that one increment of a variable v will be composed of three LLVM instructions: one load, one add, and one store.
This is just wrong, though! LLVM provides stack slots for a good reason: stack allocated variables can escape. You need a place in memory to stick them. If mem2reg can prove that the stack allocated variable doesn't escape, it gets promoted into an SSA value.
This is just wrong, though! LLVM provides stack slots for a good reason: stack allocated variables can escape. You need a place in memory to stick them. If mem2reg can prove that the stack allocated variable doesn't escape, it gets promoted into an SSA value.