Change https://golang.org/cl/313389 mentions this issue: go/ssa: implement position information for If

cc @findleyr

I am of a couple of minds about this. I see it as helpful in a lot of cases to go from ssa back to the source. However, ssa does not always smoothly translate back into source code and it does not have to as it is targeting different problems. If/conditional jump feels like it might be different enough that it is not obvious whether translating back into source with a pos makes sense.

  if a && b { foo() }

This is going to be translated into a couple of different If instructions. Which of the If statements, gets the token position of the If? Is it the one branching on "a", the one on "b" or a fake If to wrap the statement (see builder.cond). (FWIW dumping the ssa for one of these cases might help to really dig in here.)

As I mentioned on cl/313389, optimizations might not preserve this information. If instructions tend to get removed if possible.

Other options for this problem include debug instructions. Is there any chance this could work for you? Another is to add utilities that recover some of the original structure like: ssautil/switch.go. I don't know if there is anything here that would help you.