Valgrind with NEWGC (was: 21.5 crash in Gnus)

DP> I might take a look at that, especially if someone else provides DP> the solution to suppressing the reports; I have never worked with DP> valgrind before. MC> I found this in the valgrind manual: MC> --gen-suppressions=no|yes print suppressions for errors detected [no] MC> I'll see if this does the magic for us somewhen next week, if you get MC> to it earlier be my guest and go ahead ;-). Together with the excellent support of the valgrind people I was able to figure out how to use valgrind with the virtual dirty bit write barrier of NEWGC. Run valgrind with the option `--vex-iropt-precise-memory-exns=yes' to enable the magic that allows valgrind to work with the write barrier's signal handlers. By default Valgrind optimises the code it generates in such a way that the simulated registers are not always up to date, so when the exception happens, in effect some of the most recent changes to the simulated registers are lost. `--vex-iropt-precise-memory-exns=yes' disables this optimisation at the cost of some performance overhead. -- Marcus