On Wed, 2019-10-30 at 16:55 -0700, Omar Sandoval wrote: > On Wed, Oct 30, 2019 at 02:04:42PM +0100, Mark Wielaard wrote: > > Hi Omar, > > > > On Mon, 2019-10-07 at 02:05 -0700, Omar Sandoval wrote: > > > The next change will need to have the Dwarf_Frame readily available, so > > > rather than finding it again every time, let's cache it for reuse. The > > > CFI frame can also be useful to clients of libdwfl, so add > > > dwfl_frame_dwarf_frame to get it. Similarly, the Dwfl_Module is also > > > frequently needed in conjunction with the frame, so cache it and add > > > dwfl_frame_module. > > > > I can see how this is useful. But it seems the Dwarf_Frame is only > > cached when __libdwfl_frame_unwind is called. Which I believe isn't > > done for the initial frame. Also it isn't clear how to propagate any > > errors when NULL is returned. Maybe dwfl_frame_dwarf_frame () should > > check first to see if frame is NULL and then call lookup the CFI and > > call dwarf_cfi_addrframe if not? > > Yes, that makes sense. Rather than doing the lookups in > __libdwfl_frame_unwind and handle_cfi, I can move the lookups to > dwfl_frame_module and dwfl_frame_dwarf_frame, have those functions cache > it internally, and make __libdwfl_frame_unwind and handle_cfi call those > functions.
dwfl_frame_dwarf_frame should also save any errors, so that when it is called again it can set it again when returning NULL. Like what dwfl_module_getdwarf does. Thanks, Mark
