Fri Mar 9 13:48:00 GMT 2001
Andrew Cagney wrote:
> David Taylor wrote:
> > I believe that every target that does:
> > set_gdbarch_frameless_function_invocation (gdbarch,
> > frameless_look_for_prologue);
> > has a bug.
> > The function frameless_look_for_prologue invokes PROLOGUE_FRAMELESS_P
> > with one argument -- the pc of the *START* of the function.
> > For backtraces, get_prev_frame wants to know not "does this function
> > eventually set up a frame if I execute far enough into it", but rather
> > "does this function have a frame at the point where the program has
> > currently stopped".
> I don't think this is right. As far as I know, the behavour is:
> o gdb sets a breakpoint at the end
> of the function prologue
> i.e. break foo
> not break *foo
> o the target runs through to the end of
> the prologue so that the stack frame's
> construction is complete.
> GDB can only do correct backtraces after the frame has been
> constructed. GDB doesn't handle backtraces part way through a stack
> As far as I know, to make things so that GDB could re-construct a
> partially built frame, GDB would need to understand things like dwarf2's
> live range splitting stuff (correct name?) along with a few other dwarf2
> (?) features which would, together, let GDB construct its frame frame
> based on an aribtrary function address.
It varies from ABI to ABI, and base-port to base-port.
For some targets, backtrace can succeed even if you're
stopped at an arbitrary point in the prologue. Of course,
evaluation of the function's parameters probably won't work...
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