> On Jan 15, 2015, at 5:01 PM, Zachary Turner <ztur...@google.com> wrote: > > Btw, I'm still a little uncomfortable that not having unwind/ symbol info at > any point no matter how deep in a function call chain, has the possibility to > mess up a step over. In my original example, i had symbols for main but not > printf. Is that not sufficient to step over a call to printf? It should be > able to know from that a) the bounds of main(), b) the pc corresponding to > the next line of source after printf, and c) the value of esp. Aren't those 3 > pieces of information enough to step over any line of source, regardless of > whether you have unwind information for the code inside the function you're > stepping over?
The stepping machinery is not architecture specific, nor should it be. It's the unwinder's job to get the stack frames right on a per-architecture basis, and then the stepping machinery is the consumer of the unwind info. The stepping machinery also needs to know things like "how to I get back out of a function that I stepped into" which again rely on the unwind being accurate. Jim > On Thu, Jan 15, 2015 at 4:36 PM <jing...@apple.com> wrote: > > > On Jan 15, 2015, at 4:18 PM, Zachary Turner <ztur...@google.com> wrote: > > > > Which is unfortunate, because it seems to be needed even for basic stepping > > to work, like step over. Originally I was just trying to implement > > stepping, and that's how I ran into this issue. So that brings me to a > > related question. Why is step over as complicated as it is? It seems to > > me like step over can be implemented by disassembling 1 opcode, adding the > > size of the opcode to the current pc, and having the ThreadPlan::ShouldStop > > always return false unless the pc is equal to old_pc + size_of_opcode. > > > > You are describing "thread step-inst". That should pretty much always work > regardless of unwinder, etc. > > Source step over, as Jason said, is much more complicated. > > Jim _______________________________________________ lldb-dev mailing list lldb-dev@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev
