We have adopted Valgrind as a periodic QA measure: every six months, we run all our tests through it. This takes a couple of months for everything to run, so we don't feel we can do it more often. What it finds for us is uninitialized variable errors; our internal memory management takes big chunks from malloc/free, and splits them up in lots of ways, and we haven't seriously attacked the problem of teaching Valgrind about it yet.
The first pass, a year ago, found lots of stuff, since the code has been under development for more than 20 years. The second found less, and the third, recently completed, less still; developers seem to be getting used to the idea and being more conscious of the kinds of errors that Valgrind finds, which is good. So far, we'd done all of the work on AMD64 Linux, since we consider that the main variant of the platform, and the x86 to be something we want to phase out, when we get the chance. But we tried Valgrind on it, and found that there's a definite style of uninitialized variable errors that show up on 32-bit but not 64-bit. These are C "auto" variables, of integer and logical types, in functions that have a reasonable number of such. I suspect that in 64-bit code, with more registers available, these go into registers, and that Valgrind can't tell when a register stops being used for one variable by the compiler and gets allocated to another. If I'm possibly right about that, it begs the question of "could we find more errors if we had no variables in registers at all?" I'm currently working with optimised production builds for the initial scan, and de-optimising files in which that shows uninitialized variable errors while investigating them. I'm not getting extra ones showing up when I do that, but the number of errors we've found and fixed so far, about 200, is much less than the number of source files (about 4000), we could be missing them. Does GCC 4.1 still allocate variables to registers with optimisation turned off? thanks, -- John Dallman Parasolid Porting Engineer ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Valgrind-users mailing list Valgrind-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/valgrind-users
