On Sunday 08 November 2009, [email protected] wrote: > I ran across a case where valgrind reported an undefined value that I > was sure was a false positive, but after investigating more closely,
If you have a standalone test program with pcmpeq which shows a false positive, I'd be certainly be interested to see it. Considerable effort has been expended over the years in order to get rid of false positives, I'm always on the lookout for cases that were missed. > the current source code, and as far as I can tell, valgrind does not > properly handle definedness bits in the case of dependency-breaking > operations. For example: > > xor %ecx,%ecx > > should leave all of the bits of %ecx defined, regardless of whether they > were defined before or not. However, in mc_translate.c, one finds that > Iop_Xor32 is always reduced to mkUifU32, with no check that I can find > if the arguments are the same. It's true that Memcheck doesn't check for identical args to Iop_Xor32. That's because it relies on the compilation pipeline ahead of it to clean such cases up. > Should I file a bug report? Yes, please do. J ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Valgrind-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/valgrind-users
