Re: [Lilypond-auto] Issue 2513 in lilypond: Patch: Build: add -fno-tree-vrp to CXXFLAGS for gcc 4.7.0

[lilypond]

Comment #3 on issue 2513 by address@hidden: Patch: Build: add -fno-tree-vrp  
to CXXFLAGS for gcc 4.7.0
http://code.google.com/p/lilypond/issues/detail?id=2513

Taking a look at the gcc bug data base, it would appear that the -ftree-vrp  
optimization option has been around for a very long time now.  So it is  
likely that it is not solely responsible for the problem, but possibly in  
interaction with other, possibly newer, optimization options.  It is also  
likely that this option has noticeable performance impact, given that it  
has been included in GCC already a long time ago, and not being removed  
since then like other optimization options that have proven not to be  
overly effective.

A quick test might be to check the result of

g++ -O1 -ftree-vrp

If this is sufficient in itself for cranking out bad code, I agree that the  
proposed fix is likely the best we can hope to do without foregoing even  
more important optimizations.  If the code delivered by that command is  
good, then perhaps there is a different optimization option with possibly  
less impact we can switch off.

Of course, this would also be interesting information to deliver in an  
upstream bug report.  And this should very very definitely be reported  
upstream to the GCC bug data base.