Re: Issue 1997 in lilypond: segfault in tablature-negative-fret.ly

[lilypond]

Updates:
        Status: Started
        Cc: address@hidden

Comment #22 on issue 1997 by address@hidden: segfault in  
tablature-negative-fret.ly
http://code.google.com/p/lilypond/issues/detail?id=1997

Graham, you have a 64bit target.  The code generator for that is entirely  
different from 32bit systems.  It may suffer from a similar problem exposed  
under different circumstances (which might or might not be triggered in the  
Lilypond code base, although at least the regtest does not see them), or it  
may not be affected at all.  This segfault is not due to uninitialized  
variables, it is a compiler fault.  You can trust me on that.  I have a  
couple dozen years of system programming experience.

Anyway, one thing that has been useful is figuring out "target record" in  
gdb which lets you step backwards from a segfault.  Since various other  
optimizations made the stack backtrace less than useful (since the problem  
occurs with tail jump optimizations, the bad function is not actually  
present in the backtrace), this was quite helpful.

I will try seeing whether we can use a more specific option than the  
keep-inline-function stuff.  Unfortunately, I have not been able to isolate  
a nice self-contained test case that we could employ as a more reliable  
configure test than just testing for a gcc version number.

Do we have any data from 4.6.0?  I know that 4.6.1 is faulty (no idea  
whether just i386 target is affected, but at least ia64 seems less  
troubled), but nothing else.  Strictly speaking, we don't even know whether  
it is just Ubuntu's own version.

Short of more conclusive data, I'd do a configure check for >= 4.6.0 and  
rein that in when we get more conclusive data.