The spec says that's what it should do. From https://sourceware.org/gdb/onlinedocs/gdb/GDB_002fMI-Variable-Objects.html :
"Reevaluate the expressions corresponding to the variable object name and all its direct and indirect children, and return the list of variable objects whose values have changed;" Also, our Eclipse guy gets grumpy when it doesn't :-) Ted -- Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project > -----Original Message----- > From: Greg Clayton [mailto:clayb...@gmail.com] > Sent: Friday, August 25, 2017 5:00 PM > To: Ted Woodward <ted.woodw...@codeaurora.org> > Cc: lldb-dev@lists.llvm.org > Subject: Re: [lldb-dev] hang bug in lldb-mi -var-update > > lldb-mi should never be checking the children. This is never a good idea due to > performance. What happens when you have an array with a million entries? > Long delay. Aggregate types should never say they changed. Only SBValue > objects that have values should claim to change. > > Greg > > > > On Aug 25, 2017, at 10:42 AM, Ted Woodward via lldb-dev <lldb- > d...@lists.llvm.org> wrote: > > > > I found a hang in lldb-mi's -var-update. It checks to see if a var > > changed, then it checks each of the children recursively. If a child > > is a pointer back to a parent, as in this case: > > > > struct complex_type > > { > > int i; > > struct { long l; } inner; > > struct complex_type *complex_ptr; > > }; > > > > void > > var_update_test(void) > > { > > struct complex_type complx_array[2]; > > > > complx_array[0].i = 4; > > complx_array[0].inner.l = 4; > > complx_array[0].complex_ptr = &complx_array[1]; > > complx_array[1].i = 5; > > complx_array[1].inner.l = 5; > > complx_array[1].complex_ptr = &complx_array[0]; > > > > > > > > the code in CMICmdCmdVarUpdate::ExamineSBValueForChange will get into > > an infinite loop. > > > > const MIuint nChildren = vrwValue.GetNumChildren(); for (MIuint i = > > 0; i < nChildren; ++i) { > > lldb::SBValue member = vrwValue.GetChildAtIndex(i); > > if (!member.IsValid()) > > continue; > > > > if (member.GetValueDidChange()) { > > vrwbChanged = true; > > return MIstatus::success; > > } else if (ExamineSBValueForChange(member, vrwbChanged) && > vrwbChanged) > > // Handle composite types (i.e. struct or arrays) > > return MIstatus::success; > > } > > > > I've got a patch that disables checking a pointer's children. I'll put > > it up on phabricator today. > > > > Ted > > > > -- > > Qualcomm Innovation Center, Inc. > > The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, > > a Linux Foundation Collaborative Project > > > > > > _______________________________________________ > > lldb-dev mailing list > > lldb-dev@lists.llvm.org > > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev _______________________________________________ lldb-dev mailing list lldb-dev@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
