[lldb-dev] [Bug 18769] New: lldb fails to stack unwind gold linker exes that assert

[Jason Molenda]

I'd start by seeing if lldb knows where the binaries are loaded in this session.  e.g.

(lldb) im loo -a $pc

It doesn't look like lldb knows what Module you're in and doesn't have a function/symbol name either.  There's probably no eh_frame unwind info and IIRC your system's libraries are all built -fomit-frame-pointer so a blind stack walk will fail.

I don't know how solid lldb's corefile support is on Linux.  It may be that you're not able to find where all the solibs are loaded when doing core file debugging.

This is also a little disheartening,

* thread #1: tid = 0, 0x00007ffba3bb2425, name = 'lldb-gdbserver', stop reason = signal SIGABRT
    frame #0: 0x00007ffba3bb2425
-> 0x7ffba3bb2425:  addb   %al, (%rax)
   0x7ffba3bb2427:  addb   %al, (%rax)
   0x7ffba3bb2429:  addb   %al, (%rax)
   0x7ffba3bb242b:  addb   %al, (%rax)

this means that lldb is getting back 0x00's when it is trying to read memory out of the core file I expect.



On Feb 7, 2014, at 3:49 PM, Todd Fiala <tfiala at google.com> wrote:

> Yeah - I hit "enter" by accident :-)  The next comment fills in the rest.  Short version: gdb + gold linker + assert = backtrace, lldb + gold linker = assert = failure.
> 
> Not high priority, but will stop me from using the gold linker even though it gives me a 6-7% speed increase.
> 
> 
> On Fri, Feb 7, 2014 at 3:32 PM, <bugzilla-daemon at llvm.org> wrote:
> Bug ID	18769
> Summary	lldb fails to stack unwind gold linker exes that assert           
> Product	lldb
> Version	unspecified
> Hardware	PC
> OS	Linux
> Status	NEW
> Severity	normal
> Priority	P
> Component	All Bugs
> Assignee	lldb-dev at cs.uiuc.edu
> Reporter	tfiala at google.com
> Classification	Unclassified
> 
> I'm hitting an assertion in lldb-gdbserver.  On Ubuntu 12.04 x86_64, using the
> gold linker 'sudo apt-get install binutils-gold', with a cmake/ninja build, I
> am not able to get a valid backtrace out of lldb for lldb-gdbserver when it
> generates
> 
> 
> You are receiving this mail because:
> 	• You are the assignee for the bug.
> 
> _______________________________________________
> lldb-dev mailing list
> lldb-dev at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev
> 
> 
> 
> 
> -- 
> Todd Fiala |	 Software Engineer |	 tfiala at google.com |	 650-943-3180
> 
> _______________________________________________
> lldb-dev mailing list
> lldb-dev at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev